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China's new energy vehicles have gradually been promoted in the market, and the market occupied by new energy electric vehicles is becoming larger and larger. In an electric vehicle, the most core part is the motor drive system, and the performance of the motor drive system has the most direct impact on the performance of the whole vehicle. 1. New energy electric vehicle motor drive system performance requirements The performance of new energy electric vehicles depends largely on the quality of the motor control system, power supply system and motor drive system. The motor drive system is a system that provides power for electric vehicles and is the core part of ensuring the normal operation of electric vehicles. A good motor drive system needs to have the following requirements: A. The cost price of the electric vehicle drive system is almost the same as that of the internal combustion engine system, and the price is relatively low; B. Need to have good performance, has a large instantaneous power and a wide constant power and starting torque, in order to quickly achieve acceleration; C. Wide speed range, low speed operation can climb and start, in the constant power zone, low torque and have a high speed, so as to ensure that the car on the flat road normal driving, improve mileage; D. With the best capacity utilization rate, in a certain environment, the optimal mechanical efficiency and motor efficiency can be achieved, effectively increasing the energy utilization efficiency of electric vehicles, and ensuring the smooth operation of vehicles in various environments. 2. Drive motor technology A. Dc motor drive system The drive system uses DC motor. The use of DC motor has many advantages, for example, DC motor has better mechanical characteristics, speed adjustment is convenient and has good performance, easy to control, high timeliness with low cost and mature technology. B. Ac motor drive system compared with DC motor, AC motor operation efficiency is high, more reliable, does not require maintenance and easy to cool, the general use period is longer. C. In a variety of motors, the permanent magnet motor has the highest power density. The drive motor of permanent magnet synchronous drive system is composed of brushless DC motor (BLDCM) and three-phase permanent magnet synchronous motor (PMSM). The drive system is small in volume, light in weight, and has high efficiency, and does not need to invest special manpower for maintenance. At present, it has been applied in new energy vehicles. D. Compared with the induction motor, the motor structure of the switched reluctance motor drive system has higher efficiency, simple and more reliable, the rotor has no winding, and is more suitable for frequent forward and reverse rotation and impact load. A small number of power switching components are used in the drive power circuit, and the circuit is relatively simple. And the power components and motor windings are connected in series to effectively reduce the occurrence of direct short circuit, to achieve a wide speed range, low speed large torque and braking energy feedback characteristics, so the system has been a good application in new energy vehicles. 3. Advantages of new energy electric vehicle control system The energy of new energy electric vehicles mainly comes from the motor. The motor control system of new energy electric vehicles has excellent performance and can provide a better operating state for electric vehicles. In complex road conditions and bad weather, the vehicle needs to have a high performance. In the process of driving, in order to change the running state of the vehicle, the driver manually operates the vehicle. The vehicle controller receives the driver's control signal, such as accelerating the accelerator, braking, etc., and then starts the vehicle control system. After receiving the command, the motor controller sends the operation information to the drive motor. By changing the voltage, current and frequency of the power supply, the steering and speed of the drive motor are controlled. During the driving process of the car, the forward rotation of the motor can maintain the forward direction of the vehicle, and the reverse of the motor is ready to reverse. When the vehicle decelerates, the current generated by the secondary torque of the driving motor needs to be integrated and shunt processed to charge the power battery pack, and then the received motor speed information is fed back to the vehicle instrument to ensure real-time detection of the running state of the motor. In order to improve the accuracy of control, it is necessary to integrate and analyze the data of the motor and adjust it constantly. Therefore, as a core component of electric vehicles, the motor control system needs to meet the following three advantages: A. The motor control system can meet the frequent start and stop, in the more severe weather and complex environment, the electric vehicle can still maintain a stable operating state under the artificial start and stop operation. B. To upgrade the indicators and controls of electric vehicles, in order to maximize the value of tram energy, it is necessary to strengthen the durability of the battery and make the components have good compatibility. C. After a long period of complex and frequent operation, the motor still has a strong sensitivity, and when the temperature difference of the external environment is within the range of 30~130C, the motor can still operate effectively. The performance of motor and control system is directly related to the safety performance of electric vehicles. At present, electric vehicles have been able to meet the basic needs of People's Daily life. At present, there are still some technical problems in the research on the driving range and energy of new energy vehicles to be solved, but with the development of human science and technology to a certain level, these technical problems will be solved in the near future.

1. The drive axle lightweight demand The total mass of non-breaking drive axle and wheel, brake and brake drum accounts for about 11% to 16% of the chassis mass of ordinary trucks, and about 3.5% to 5% of the total mass of vehicles for heavy goods vehicles, its proportion is larger. The lightweight drive axle not only reduces the unsprung mass, reduces the running noise, improves the vehicle comfort and passability, but also reduces the material use and its own power consumption. 2. The main methods of low-cost lightweight technology Automotive lightweight needs to consider five factors: performance, function, process, cost and weight. Low cost lightweight requires the minimum cost, weight and process investment in exchange for the best safety, NVH, durability and other performance, and to achieve the corresponding system functions. 3. Drive axle development status The drive axle is the mechanism at the end of the drive line that changes the speed and torque from the transmission and transmits them to the drive wheels. The drive axle is generally composed of the main reducer, the differential, the half shaft and the drive axle housing. In addition, the drive axle also has to withstand the vertical force between the road and the frame or body, the longitudinal force and the lateral force, as well as the braking torque and reaction force. With the continuous progress of automotive technology, the drive axle reflects the application of lightweight technology to different degrees. 4. New material application of drive axle At present, the use of lightweight materials is one of the most important ways to achieve lightweight goals. The use of materials to achieve lightweight is mainly divided into two cases, one is the use of low-density materials, such as aluminum alloy, magnesium alloy, alloy, plastic or a variety of composite materials; The other is to use high-strength materials, so as to reduce the amount of material, reduce the weight such as the use of high-strength steel and so on. Weight loss effect: Taking aluminum alloy as an example, the density is only 1/3 of the density of iron, based on structural optimization analysis, its weight loss effect can reach 40%-60%. 5. New technology application of drive axle In the product design and development, under the premise of ensuring the product structure and performance requirements, try to use new technologies or processes to integrate and hollow the structure and parts, so as to reduce the weight of the product and achieve the goal of lightweight. At present, the most widely used forming technology mainly includes laser welding, internal high pressure forming technology, hot pressing forming, hydraulic forming, powder metallurgy and other technologies. Drive axle housing: The domestic drive axle housing mostly uses the traditional casting axle housing and stamping welding axle housing. The high pressure forming in the drive axle housing is a new process, with high material utilization, energy saving, material saving, consumption reduction, fewer processing procedures, high processing efficiency, easy to realize mechanization, automation, reasonable wall thickness distribution of parts, high strength, stiffness, light weight and other advantages. 6. Application of structure optimization technology Through finite element analysis technology, based on vehicle performance indicators such as mass, fatigue life, stiffness and modal frequency, the drive axle lightweight collaborative optimization design process is established. Sensitivity analysis, topology optimization, size optimization, morphology optimization, multi-objective genetic method and other optimization methods are adopted, combined with lightweight materials and advanced technology applications, under the condition of achieving manufacturing feasibility and weight reduction standards. The performance meets the development target requirements. 7. Drive axle lightweight technology development trend Lightweight technology innovation strategy: Establish a cooperation mechanism between production, learning, research and application, from the development and promotion of materials to parts, give full play to their respective advantages such as high efficiency, enterprises and research institutes, accelerate the transformation of scientific research results, and effectively promote the development and application of lightweight technology innovation products. Drive axle parts integration, hollowing, lightweight, composite, localization is a hot spot in order to reduce costs, based on the integration of structural optimization technology and hollowing, based on the application of new materials, based on performance and cost consideration of composite, domestic replacement of imported materials is a hot spot of technology development. Drive axle optimization technology application can minimize costs: through the integrated design of the drive axle components, fully consider the functions of multiple parts, combined with CAE analysis technology optimization, can shorten the development cycle, reduce research and development costs, and improve the market competitiveness of the product. Lightweight evaluation and reasonable control of cost: the lightweight design and application of the drive axle need to cover the target set of the production process and maintain the balance between materials, processes and costs, and find the preferred target set in order to finally achieve the established lightweight design goals, which has become the future direction and development trend of the lightweight application of the drive axle.

New energy vehicles are extended on the basis of the traditional automobile industry chain, and the biggest difference between the structure and the traditional car is the power system, which increases the battery, motor, electric control system and other components. 1. Power density In terms of power density, the US Department of Energy report requires the peak power density of the drive system (motor + electronic control) to reach 5kw/L in 2020, significantly increased to 33kw/L in 2025, decomposed to the electric control is 100kw/L, decomposed to the drive motor is 50KW/L. 2. Requirements for drive motors of new energy vehicles The vehicle drive motor is the core key component of the electric vehicle power system, and its performance directly affects the vehicle performance. China's self-developed permanent magnet synchronous motor, AC asynchronous motor and switched reluctance motor have achieved small and medium-sized batch matching with domestic vehicle enterprises, and the power range of products covers the power needs of vehicles below 200kW. a. For quick start and capability to climb steep hill b. For high speed cruise and overpass capability at high speed c. High power density d. Energy saving 3. Classification and technical characteristics of automotive motors Currently in use or development of electric vehicle motor mainly direct current motor (DCM), induction motor (IM), permanent magnet motor (PM), switching magneto motor (SRM) four categories. 3.1 Types of vehicle motors According to the type, the drive motor is divided into AC motor and DC motor, in the DC motor, low-speed electric vehicles mainly use series motor and other excited motor. 3.2 In AC motor applications a. Asynchronous motor is mainly used for electric bus traction motor b. Switched reluctance motor is mainly used in hybrid vehicles c. Permanent magnet synchronous motor is mainly used in passenger cars and commercial vehicles drive motor 3.3 In terms of motor types and characteristics The permanent magnet synchronous motor is superior to DC motor, asynchronous motor, switched reluctance motor and brushless DC motor in starting performance, peak efficiency of rated operating point and power density of high efficiency operating area. Permanent magnet synchronous motors are comparable to induction motors in terms of constant power speed range, torque stability, motor reliability and NVH. 4. Requirements for the use of motor design requirements for motor The permanent magnet synchronous motor (PMSM) system has the characteristics of high control precision, high torque density, good torque stability and low noise, and is an ideal drive system for electric vehicles. 4.1 Dynamic Performance requirements Wide speed range, large torque overload ratio, maximum no-load back potential limit and maximum current limit. 4.2 Integration requirements High sustained power density, peak power density. 4.3 Global Efficiency Requirements Low energy consumption, high efficiency in a wider range, high efficiency in frequent working areas, specific methods: determine the basic design parameters of permanent magnet motor, determine a set of minimum sets as design variables; It is described by three design dimensions: performance, efficiency and power density. 4.4 Efficient Area Planning The motor efficiency calculation based on rated working conditions is optimized to the motor average efficiency calculation based on cycle working conditions, and the analytical relationship between the high efficiency zone of permanent magnet motor and the motor parameters is established. In fact, the high efficiency zone of permanent magnet motor can be planned to improve the energy utilization rate of electric vehicles. 4.5 High power density design Loss distribution: Reasonable distribution of motor component losses, so that the temperature rise of each part is maintained within the limit, the establishment of iron loss model. 4.6 Power density design: Establish an automatic power density optimization process The thermal network is used to calculate the temperature rise, and the efficiency oriented optimization design with temperature rise as the boundary is carried out by the improved optimization calculation method. 4.7 Method of motor noise reduction a. Motor pole groove matching optimization: the vibration noise in low frequency band of permanent magnet motor is related to the design parameters such as the motor pole groove, and the selection of a reasonable pole groove can reduce the low frequency noise of the motor b. PWM(pulse width modulation) optimization: The influence of PWM on the vibration noise of permanent magnet motor is mainly distributed in the frequency near the switching frequency and its multiple, and the PWM strategy can be optimized to reduce the motor noise.

As the first medium-speed high-power ammonia fuel engine in China, its single cylinder power can reach 208kW, ammonia energy accounts for 85%, reducing carbon emissions by 80%, and emissions meet the national standard two-stage standard. The engine adopts low pressure electronic control multi-point injection of ammonia gas and high pressure electronic injection of diesel to precisely control the fuel supply. VTG supercharger is used to achieve accurate air-fuel ratio control within the operating range. In many aspects of power level, economy, emission, technology and reliability in the international advanced, domestic leading level. 12V240H-DFA ammonia fuel engine with high safety, equipped with dual ECU, knock control, fire control, and double-layer gas supply pipe system, can achieve diesel injection, ammonia injection and security independent control, to achieve the intrinsic safety of the engine. For the key components and systems of the ammonia fuel engine, the R&D team designed the combustion system, gas supply system, fuel mixer and other related key components of the ammonia fuel engine, and optimized the injection system of diesel and ammonia gas to maximize the combustion efficiency of the ammonia diesel dual-fuel mode. The subsequent 12V240H-DFA ammonia fuel engine will be installed in the first ammonia fuel tug in China to realize the demonstration application of ammonia fuel engine.

On November 20th, Professor Feng Huihua, Chairman of the Design and Intelligent Manufacturing Branch of China Internal Combustion Engine Society, led a team to Yuchai for a visit and communication, aiming to solve the problems encountered in the engine production process with the help of the theoretical knowledge of the branch in internal combustion engine design and intelligent manufacturing, break through the key technology of design and manufacturing, and realize the production, study and research. Promote the development of enterprises with advanced theories and technologies in universities. In the morning, the team visited Yuchai Science and Technology Museum and engine production line. Yuchai Mo Qixing, deputy chief technology engineer of Yuchai, introduced Yuchai's development history, advanced engine technology, engine production line, etc., and discussed the main market and advanced engine technology of Yuchai at present. Then, Mo Qixing introduced Yuchai's advanced manufacturing technology, and put forward the main problems Yuchai faced in the engine manufacturing process, such as hydrogen embrittleness of hydrogen engine materials, emulsification of hydrogen engine lubricating oil, friction of valve seat ring, process big data application, engine factory abnormal noise detection, etc. In view of the above engine manufacturing process problems, the two sides launched a fierce discussion, and put forward some effective solutions. In the afternoon, Benjie introduced Yuchai's innovation capability and 1235 strategy, and put forward the main problems faced in engine design, including: the correlation between 0.5 order noise and combustion parameters of diesel engines, the relationship between fuel economy and emissions, how to deal with domestic common rail system and do a good job in the future and long term planning. The participants of the branch offered suggestions for the problems raised by Yuchai, and reached a consensus on the solutions to some problems. Finally, Professor Feng Huihua said that the branch will maintain close contact with Yuchai to jointly overcome the problems faced in the process of engine design and manufacturing, and jointly support the sustainable development of clean and efficient internal combustion engine technology in the context of electrification In the later stage, the branch will continue to strengthen cooperation and exchanges with Yuchai, continue visits between members of the branch, improve the influence of the activity in the internal combustion engine academia and industry, and aim to build the exchange activities of members and units into brand activities of the China Internal Combustion Engine Society, while improving the level of internal combustion engine design and manufacturing in China.

On November 22nd, according to the Ministry of Transport, the "E-Road Unblocked" Wechat mini program is officially launched for trial operation. The public can check the location, real-time status, charging mode and other information of the national highway charging facilities through the "Charging Pile" module of the "E-road Smooth" application program. Officials pointed out that by the end of October this year, China has built a total of 6,257 charging parking space service areas, accounting for 94% of the total number of highway service areas. A total of 20,000 charging piles have been built in highway service areas across the country, covering 49,000 minibus parking Spaces. The coverage of charging facilities in highway service areas in 11 provinces (municipalities), including Beijing, Liaoning, Jilin, Shanghai and Zhejiang, has reached 100 percent. At present, the "E-road Smooth" has initially completed the collection and aggregation of charging information. In addition, the "Sunshine rescue" module of the "E-road Smooth" application program was launched simultaneously for trial operation, which realized the "one-click call for help" function of the national highway and the "three openness" of rescue services, that is, the openness of rescue service telephone numbers, rescue service points and charging standards. Rescue channel inquiries are more convenient, rescue service charges are more transparent, rescue selection is more independent, and service supervision is more standardized.

On October 26th the vehicle test for the selection of the top 10 new energy vehicle power systems in 2023, "Chinese Heart", was kicked off with strong support from Gaoyou government. The power systems of 15 models, including Smart#1, Ora EV, Chery eQ7, SGMW Wuling Binguo, SGMW Cadillac LYRIQ, Tesla Model Y, Risingauto F7, Leapmotor C10, FAW Toyota bZ3, SAIC Volkswagen ID.6X, ZEEKR 009, Hozonauto Hozon S, AITO.Auto SUV M7, Deepal S7, and BYD Yangwang U8, stood out from the preliminary selection list. With the development of the market and the current global energy crisis, China's new energy vehicles have entered a stage of rapid development. The company has provided more differentiated products for the market, and its product strength has increased rapidly year by year to further meet the diversified needs of the market. As a professional manufacturer and service provider of small-batch& multi-variety high-precision prototype, Wuxi Shinden has been deeply engaged in automotive power system for many years. The main products mainly includes motor housing, motor end cover, reducer housing, new energy tram battery pack, internal water jacket, etc.,In 2022 it was also awarded "Top 10 Component Enterprises of the Year". This year Wuxi Shinden also sponsored this selection, and Mr. Peng Gaolou, the general manager of the company, attended the event and participated in the drive test. "Among the power systems shortlisted this year, the degree of integration is higher and the power output is higher. Companies also pay much attention to the balance between performance and the overall vehicle development. The comprehensive quality of all models such as appearance, interior and configuration has also been improved significantly." said Yin Chengliang, Vice Dean of the Automotive Engineering Research Institute at Shanghai Jiao Tong University and Director of the Expert Review Committee for the "Chinese Heart" Annual Top Ten New Energy Vehicle Power Systems Selection. In 2023 the increasingly competitive new energy vehicle market continued to grow at a rapid pace. According to the latest production and sales data from the China Association of Automobile Manufacturers, the sales volume of traditional fuel vehicles was 6.886 million units in the first nine months of this year, 4.7% year-on-year decrease, while cumulative sales of new energy vehicles reached 2.361 million units, representing a growth of 49.8%, and the market penetration rate is also rapidly improving. With the rapid iteration and upgrade of products, the technology of new energy vehicles is also continuously optimized. In addition to the price competition, major car companies will also consider various aspects such as product technology improvement, innovation, so as to meet the diverse needs of consumers. They will be well-prepared to meet the challenges in terms of product competitiveness. Wuxi Shinden will, as always, support the innovation and development of the automotive industry in product R&D, and meet market demands more quickly.

Wuxi Shinden is planning to participate in the upcoming CTI Symposium, which will be held in Berlin, Germany in December. The company will be showcasing its latest products. The CTI Symposium is widely recognized as a premier event in the automotive industry, attracting professionals from around the world. It serves as a platform for companies to showcase their innovative technologies and advancements in the field of automotive engineering. This year Wuxi Shengding is proud to be part of this esteemed gathering, highlighting its commitment to research and development. One of the key products to be displayed is the transparent reduction shell. This groundbreaking innovation allows for a clear view of the internal mechanisms, providing valuable insights for engineers and enthusiasts alike. The cast motor housing, another highlight of the exhibition, offers exceptional durability and precision, meeting the highest industry standards. In addition, Wuxi Shinden will also present its inner water sleeve, which is designed to enhance the cooling efficiency of automotive system in new energy car. Lastly, the hybrid casings will be on display, showcasing the company's expertise in manufacturing components for hybrid vehicles. "We are glad to participate in the CTI Symposium and have the opportunity to present our latest products to the global audience," said Mr. Zhang, Marketing Director of Wuxi Shinden. "Our team have worked for years to develop these innovative solutions, and we are confident that they will contribute to the R&D in the automotive industry." Wuxi Shinden is dedicated to research and development in automotive, with the commitment to quality and innovation. We are ready to be a trusted partner for global automotive brands.

It was announced today that the company will be moving into a new intelligent factory in early 2024. The new factory, spanning an impressive 3000 square meters, signifies the company's commitment to innovation and advanced manufacturing, The intelligent factory, equipped with over two hundred manufacturing and inspection equipment, will significantly increase the company's production capacity. These advancements will aid in maintaining a competitive edge in the market and meeting the growing demand for the company's products. "Moving into this new intelligent factory is a significant milestone for our company," said the CEO. "This move not only represents our growth but also our commitment to embracing cutting-edge technology and innovation. We believe that this new facility will be a game-changer for our operations and will enable us to serve our customers better." The intelligent factory is designed to be flexible and adaptable to meet the changing demands of the market. It will feature advanced robotics and automation systems, and AI-driven processes for enhanced precision and quality control. The move to the new factory is expected to create several new jobs, contributing to the local economy. The company is also planning to invest in training programs to equip its employees with the skills needed to operate and manage the advanced systems in the new factory. The company's move to the new intelligent factory in 2024 signals a new era of advanced manufacturing and innovation. It is a significant step towards the company's vision of becoming a leader in its industry, driven by technology and sustainability.

Abstract: Aiming at the problems of poor quality and low economy of gear shifing of electric vehicle, the new type of electronically control-ing AMT was proposed. The transmission was based on the structure and principle of normal AMT. The DC brush motor was used as a selectand shift gear motor of electronically controlling AMT. Therefore, MPC5634 microcontroller from Freescale was selected to design the hardware circuit of the transmission controller, and the main program and various sub-nodule programs of the controller were designed by relerrinto the basic control mode of nomal electronically controlling AT and the CAN communicating module and serial communicating modulesor achieving the data translering belyeen ECU and the controler of the electronically controlling AMT were added. The bench tests of geashifting of the controller indicates that the design of the controller can be an efficient shifting operation and a stable performance. Key words: electric vehicle: automatic mechanical transmission(AMT): CAN communication: shift motor At present, transmissions suitable for electric vehicles have also become one of the hot spots in electric vehicle research. Electronically controlled electric mechanical automatic transmission has been widely used in electric vehicles due to its advantages of simple structure and good reliability. At present, the international research on AMT shift control technology of electric vehicles mainly focuses on two aspects: gear shift process control and shift law research. Gear shift process control technology determines the shift quality and driving smoothness of electric vehicles during driving, and is one of the important research directions of mechanical automatic transmission control, and the shift motor is the B shift execution power source of AMT that affects the performance of AMT controller. In this study, an electronically controlled mechanical two-speed automatic transmission is proposed. How the AMT controller works AMT is a typical closed-loop control system, which consists of three parts: sensor, actuator and controller. The AMT controller is responsible for receiving the sensor signal and sending instructions to the actuator, while collecting the current of the shift motor as a feedback signal to control the output torque of the shift motor. The AMT system works as shown in Figure 1. According to the driver's driving behavior, the AMT controller performs corresponding gear shifting operations according to the shift control strategy when it receives the accelerator signal, motor speed signal, brake pedal signal, vehicle speed signal and gear signal. The gear position signal is provided by the internal Hall sensor of the AMT system, the vehicle speed signal and the motor speed signal are obtained through CAN to reduce the occupation of the electrical resources of the whole vehicle, and the current feedback signal is obtained by the current sampling module. 2 AMT controller hardware implementation 2.1 MPC5634 features MPC5634 is an automotive-grade 32-bit microprocessor chip produced by Freescale in the United States, with 1.5 MB Flash EEPROM storage space and 94 KB RAM running memory to meet the storage and operation requirements of AMT control programs; Built-in phase-locked loop hardware module, with internal overclocking function, speed up software running speed, reduce electromagnetic interference to other devices, and the overall operation is more stable. 2.2 Hardware architecture The AMT controller's power module converts the on-board 12V voltage to 5V and 3.3V for the MCU and various sensors. The MCU receives digital signals, analog signals, pulse signals, vehicle speed signals from CAN bus networks, motor speed signals, etc. collected from various sensors to realize the MOSFET driver chip output two PWM signals to control the conduction of the control chip. The driver chip amplifies the weak electrical signal from the MCU to meet the current driving the MOSFET tube. Rectification and voltage regulation consist of an H-bridge circuit consisting of two four P-type MOSFETs to drive two brushed DC motors for gear shifting. The current detection mode is used to feedback the magnitude of the shift motor current, and the feedback signal is supplied to the driver chip for hardware protection and the other to the MCU for software protection, so as to meet the static and dynamic requirements of the entire system at the same time. Starting from the functional requirements of the AMT controller, the controller hardware architecture designed in this article is shown in Figure 2. 2.3 AMT hardware module design AMT controllers mainly include power supply module, main controller module, drive circuit module, CAN communication module, SCI communication module, current sampling module, JTAC debug module and overcurrent protection module. 2.3.1 CAN communication circuit The MPC5634 microcontroller has a built-in MSCAN module and supports CAN20A/B protocol. The schematic of the CAN communication circuit of the AMT controller is shown in Figure 3. 2.3.2 Motor drive circuit design The electronically controlled electric AMT system uses the DC brush motor as the power source of the shift actuator, and the MOSFET is used as the electronic switch, here the author chooses the AUIRFS8403 MOSFET of the international rectifier IR company as the electronic switch, which can fully meet the drive needs of the electronically controlled AMT optional column motor. In addition, considering that the electrical signal output at the pin end of the single-chip microcomputer cannot directly drive the chip to work, the author proposes to use IR's AWIRS2004S DC motor H-bridge special driver to amplify the driving current and then drive the on-off switching of the electronic switch. Two AUIRS2004S driver chips are used here to layout the drive circuit, send two PWM waves through the main control chip, realize the switching of four MOSFETs of the H-bridge drive circuit of the DC motor, realize the forward and reverse rotation and braking back of the motor, and also have overvoltage, undervoltage and overcurrent protection functions." In addition, the main control chip can realize the monitoring of the working condition of the driver chip. The schematic of the motor drive circuit is shown in Figure 4. 2.3.3 Current sampling circuit design The shift motor of the AMT system has a rated power of 60W, a rated voltage of 12V, a sampling resistor of 0.005Ω, a sampling resistance voltage drop of 0.025V, a magnification factor of 100 times, and a voltage signal corresponding to the maximum current is converted to the A/D conversion range of the single-chip microcomputer within 5V. LM358 is selected as an operational amplifier, the voltage signal is amplified and input to the AN16 port and AN17 port of the single-chip microcomputer, and the current sampling and releasing circuit is an analog circuit, and the analog ground and digital ground are isolated with a 0Ω resistor to improve the sampling accuracy and avoid phase interference. The schematic diagram of the current sampling circuit can be seen in Figure 5, the voltage amplification depends on the ratio of resistors R51 and R50, and capacitors C48~C50 are used to filter high-frequency noise signals and improve sampling accuracy. 2.3.4 Core system board circuit The core system board is a relatively independent PCB board, which is mainly composed of power supply part, crystal oscillator circuit, reset circuit, JTAG circuit and other parts. The core system board circuit is shown in Figure 6. AMT controller software implementation Combined with the control objectives of the AMT controller, determine the control mode of the AMT controller. 3.1 Overall design of the AMT software part The software part of the electronically controlled electric AMT control system adopts modular programming, and the main program of the electronically controlled AMT control system is shown in Figure 7. The EV key is inserted, the ON gear switch is turned on, and the control system is activated. First, the interrupt is closed, and the main control chip I/0 port, A/D module, CAN bus module, PWM module, clock module EEPROM and serial communication module are initialized, and the interrupt is turned on after completion. The automatic transmission control unit performs to detect whether the subsystem of each module is in the normal flag position, report an error message if the system is abnormal, and wait for the START signal of the ignition switch if it is normal. After the driver turns on the ignition switch, the TCU first reads the shift lever position signal, according to which the driver's operation intention is judged, and then obtains the speed, vehicle speed, throttle opening signal, etc. of the power motor through the CAN bus, and carries out gear shift control according to the pre-formulated shifting law. After completing the gear change and meeting the conditions for sending CAN messages, the current gear signal is sent to the vehicle control scraper through CAN communication. 3.2 Control algorithm design The system adopts an electronically controlled electric shift actuator as the shift drive mode, so there is a situation where the positioning accuracy is low. In order to ensure the accurate realization of gear shifting and gear selection actions, smooth and fast gear shifting, the classic proportional-differential (PD) control algorithm is adopted for the shift motor to realize the closed-loop control cabinet of the shift position sensor and the position sensor feedback signal current The control of the AMT actuator based on the PD algorithm is shown in Figure 8. 4. Analysis of experimental results In this paper, the self-designed AMT controller is tested on a bench, and the operation of the shift motor under actual working conditions is shown in Figure (9~11). Finally, when the PWM duty cycle is 90%, the working condition of the selected shift motor is the most ideal, and the current speed is measured by the motor speed tester to be 22rad/min. From the motor current characteristic curve in the figure, it can be found that there is a slight glitch phenomenon caused by the motor back EMF at the top of the drive signal waveform. After the above-mentioned bench test, the author next conducted a vehicle road test. Due to the limitations of the test conditions, subjective judgment is used here to confirm the smoothness and comfort of the shifting process. Through the vehicle road test, the test results of the AMT control system are obtained, as shown in Table 1. In the case of no load, this study verifies that the AMT control system can drive the shift actuator to perform the shift operation according to the instructions issued. The shifting smoothness is better, and the shift impact is relatively small. 5. Conclusion In this study, a two-speed mechanical automatic transmission controller for electric vehicles was designed based on Freescale's MPC5634 main control chip, and CAN communication function was added. After the bench test verifies, the results show that the controller software and hardware work normally, the shift motor runs forward and reverse, and can perform shift operation for the input signal in real time. In the vehicle test, the electric vehicle can quickly and accurately realize the shifting action during driving, which effectively reduces the shift impact of the AMT transmission and improves the riding comfort of the electric vehicle. The results of this research can realize the more efficient operation of the electric vehicle drive system, which has certain engineering practical value.

With the rapid development of the automobile industry and the increasing number of car ownership, pollutant emissions are increasing, environmental problems are becoming more and more prominent, and the development of new energy vehicles has become the main trend of the future development of the automotive industry.com. Reducer is one of the core components of electric vehicle transmission system, which directly bears the impact of motor and wheel rotation, and its life span directly affects the reliability and economy of electric vehicles. Therefore, it is important to research and develop the reducer for new energy vehicles. Planetary gear reducer, also known as planetary reducer and Ho-Service reducer, is widely used. As an alternative to fixed drive shaft transmission, multiple planetary wheels share the load between them thus making rational use of the internal gear unit to improve efficiency. Compared with other reducers planetary reducers have the advantages of small size, high efficiency, large ratio range and low influence by load. 1 Program selection Cylindrical gear reducer is produced by carburizing, quenching and grinding, etc. It has high load carrying capacity and low noise level, so it is commonly used in mechanical conveying and also used in the transmission mechanism of other general machinery. It has the advantages of high load carrying capacity, long life, small size, high efficiency and light quality. The classification of gears mainly includes helical, straight and herringbone teeth. Straight gears are mainly used in the field of low speed and low load transmission; helical gears are often used in automobile reducers because they can have relatively high transmission speed. After comprehensive consideration, this paper selects helical gear as the main transmission gear of this reducer. 2 Reducer design The gears of the reducer used for the automobile transmission need to consider more factors. Straight cylindrical gears have lower stress requirements, and helical cylindrical gears have more advantages than straight cylindrical gears, so this design uses helical cylindrical gears. According to the actual working conditions of the gear reducer gear material selection 40Cr, and tempering treatment, gear precision for the fifth grade, select the grinding process. According to GB/T18385-2005 "electric vehicle power performance test methods" requirements type, for the transmission ratio of the vehicle driving the maximum speed and the impact of the climbing degree of two aspects of the calculation, the reducer speed ratio should be between 7 ~ 9, and can meet the car's power, economy and reliability of the design requirements. According to the relevant information and standards, the total transmission ratio was finally determined as 8.7, which was reasonably distributed, with the first stage speed ratio as 3.4 and the second stage speed ratio as 2.5. The number of gear teeth was calculated according to formula (1). The number of teeth of the first-stage active gear is 21, and the number of teeth of the first-stage driven gear is 72, which can be calculated by formula (1). The number of teeth of the second stage active gear is 24, and the number of teeth of the second stage driven gear is 61, which can be calculated by formula (1). CATIA software was used to model and design each part of the reducer individually, and then the assembly module was used to assemble it, and finally the three-dimensional model of the helical garden column gear reducer was obtained (Figure 1). 3 Strength analysis of gears The finite element analysis process includes the establishment of the finite element model, the definition of material properties for the division of the mesh cells, the imposition of load boundary conditions, the data analysis processing and calculation, and the visualization and output of the analysis results. Since the gear is the main load-bearing part, Workbench is used to perform finite element analysis of the gear to ensure the reliability of the design. The material chosen for the gear is 40Cr, with a density of 7820 kg/m', Poisson's ratio of 0.227, modulus of elasticity of 211 GPa, and yield strength of about 900 MPa. The gear is first roughly meshed, and then the relevant parameters are adjusted for detailed partitioning and updating. Determine its boundary conditions and constraints, load should be added to the gear, and torque should be added at the gear stress, and then the strength analysis of the gear is carried out, and the stress cloud diagram and gear displacement cloud diagram of the gear are derived (Fig. 2 and Fig. 3). From Fig. 2 and Fig. 3, it can be seen that the maximum displacement of the gear after applying the restraint is 0.567mm, and the maximum stress of the gear in this case is 752MPa, which is less than the yield stress of the material 900MPa, so the strength of the gear meets the design requirements. 4 Strength analysis of the shaft The material selected for the drive shaft is 40Cr, and the same finite element calculation is carried out for it, and the corresponding constraints and torque loads are applied to the drive shaft after the mesh is divided. The stress distribution and displacement cloud of the drive shaft are calculated (Figure 4 and Figure 5). From Fig. 4 and Fig. 5, we can see that the maximum displacement of the drive shaft is 0.135mm after applying the restraint, and the maximum stress of the drive shaft is 655MPa under this circumstance, and the stress is concentrated at the shoulder of the first half section, which is less than the yield stress of 800MPa, so the strength of the drive shaft can meet the design requirements. 5 Conclusion In this paper, the gearbox of the electric vehicle was designed, the transmission ratio was calculated, the gear parameters were established, and the relevant materials were selected. The gear and drive shaft models of the gearbox were imported into Workbench software, and the stress and strain were calculated and analyzed, and the results showed that both of them meet the mechanical properties of the materials. Therefore, it can meet the requirements of engineering use and has certain engineering reference value for the development and design of electric vehicle reducer.

Abstract: Compared to single fixed speed-ratio reduction gear, two-speed AMT can reducerequirements for battery and motor performance of the complete vehicle system, but reasonable shiftstrategy is required to ensure that requirements of vehicle economy and power can be met. Firstly, this paper analyzes changes of battery , motor and transmission efficiency under the driving conditionwith changes of vehicle speed and accelerator pedal opening. To realize the goal of maximum systemefficiency, the paper designs an optimal economic shift strategy. Secondly, the paper analyzeschanges of the accelerated speed under different shifts with changes of vehicle speed and acceleratorpedal opening. To realize the goal of maximum system efficiency, the paper designs an optimaldynamic shift strategy. Finally , the paper designs a shift strategy switch controller, makes up powerconsumption of 100 kilometers and acceleration time into comprehensive performance index, calculates power demand factors based on the fuzzy theory, and selects corresponding shift strategy based onpower demand factors. The simulation and experiment results show that compared with the traditionalshift strategy, the average power consumption of 100 kilometers is reduced by 9. 97%, and theacceleration is slightly worse by about 3. 96% . Therefore , the shift strategy can not only ensure thedriver's power demand, but also improve the economy and extend vehicle endurance mileage.Key words: two-speed AMT;system efficiency; fuzzy control; dynamic demand factor;switching controller. In order to reduce the performance requirements of the battery and drive motor for pure electric vehicles, they are generally matched with multi-gear automatic transmissions, of which two-speed AMT is a hot research topic with the advantages of simple structure, low cost and high transmission efficiency. In order to balance the economy and power of the vehicle, and to ensure that the drive motor always works efficiently, a reasonable shift strategy for the two-gear AMT needs to be designed. Around this problem, experts and scholars at home and abroad have conducted a lot of research. Xiao Lijun et al. proposed an integrated and coordinated control method including the drive motor, using PID and finite state switching control strategy to regulate the motor speed, and the simulation and bench test results show that the drive motor participates in the gear shift, and the gear shift process is faster. Liu Fuxiao et al.2 developed a power and economy shifting strategy with the objectives of shortest acceleration time and highest drive motor efficiency, respectively, and designed a switching controller based on fuzzy theory. simulation results showed that the method can ensure the economy and power of the vehicle. fu Jiangtao et al. established an optimal energy consumption model and introduced two additional cost functions to prevent frequent shifting. Simulation and test results show that the strategy effectively reduces the vehicle energy consumption over 100 km. Li Congbo et al. proposed an economic mode shift strategy with low energy loss, and developed a drive motor torque calculation method. At present, the development of common shift strategy only analyzes the characteristics of the drive Shen machine and its efficiency changes, or calculates the minimum output torque of the current drive motor with the goal of minimum energy consumption, which improves the vehicle economy to a certain extent, but will greatly sacrifice the vehicle dynamics5-. The efficiency of the power battery and the efficiency of the transmission in the pure electric vehicle power system are also key factors affecting the range of the vehicle. At the same time, the current widely used shift strategy is an off-line gear selection method, which cannot be dynamically adjusted for different driving conditions. In this paper, the efficiency model of the drive motor, battery and transmission is built to analyze the changes of the system efficiency under each driving condition, and the best economic shift strategy is formulated with the goal of the highest system efficiency. In order to ensure the dynamics of the vehicle, the best dynamics shift strategy is developed with the goal of maximum acceleration. Finally, a power demand factor calculation method is designed based on the fuzzy theory to determine which shift strategy should be used for the vehicle at this time by the power demand factor. The simulation and test results show that the designed shifting strategy can ensure that the vehicle can meet the driver's power demand and also increase the range of pure electric vehicles. 1 Transmission System Structure This study is based on a pure electric vehicle equipped with a two-speed AMT. The transmission system of this vehicle consists of a power battery, a permanent magnet synchronous motor, a two-gear AMT and a differential, as shown in Figure 1. The powertrain integrated controller is responsible for transmitting control signals to the battery, motor and two-gear AMT, while the electric energy is transferred between the battery and the permanent magnet synchronous motor, and the mechanical energy is transferred between the motor, two-gear AMT and differential. Since the drive motor has a fast response, the two-gear AMT adopts a clutchless structure, as shown in Figure 2. 2 Shift strategy design 2.1 Transmission system efficiency analysis When formulating an economic shift strategy, the efficiency changes of the powertrain components need to be fully considered. Since the efficiency of other components is high and does not change significantly under each driving condition, only the efficiency changes of drive motor, power battery and transmission are analyzed in this paper. 1) Drive motor efficiency model to establish the permanent magnet synchronous motor model mainly has 2 methods, theoretical analysis and experimental modeling. Theoretical analysis modeling is to establish the differential equations describing the motor characteristics by analyzing the force and electrical principle of each part of the permanent magnet synchronous motor. However, because of the complex electromagnetic coupling relationship inside the motor and some parameters are difficult to measure, the experimental modeling method is used to analyze the efficiency change of the drive motor by collecting the speed, power, torque and other data of the motor under different g-subject loads, establishing a data table that can describe the actual dynamic characteristics of the motor, and using table look-up and interpolation to obtain the efficiency of the motor under different working conditions. Figure 3 shows the surface of motor efficiency Nm with motor speed Wm and torque Tm To facilitate the analysis of the motor efficiency, Figure 3 is projected onto the motor torque-speed plane to obtain the contour plot of motor efficiency shown in Figure 4. It can be seen from Fig. 4 that the motor efficiency is low when the motor speed is below 2000r/min and the output torque is below 150N-m. Therefore, when designing the shifting strategy, the drive motor should be avoided to work in this interval. 2) Power battery efficiency model Iron phosphate carp battery is a widely used vehicle power battery, and its operating performance is affected by temperature, terminal voltage, single cell SOC and other factors. As the working process of the battery is a complex chemical reaction process, it is also difficult to establish an accurate mathematical model through theoretical analysis. Therefore, in this paper, the efficiency model of the battery is established by combining experiments with numerical fitting. Since this study only involves the upshift strategy of pure electric vehicles, only the power battery discharge efficiency model is established here. The specific method is as follows: CKHF-500V500A intelligent discharger is used for the test, and the test temperature is set in the range of (35 2)C with reference to the working temperature of the battery during the normal driving of the pure electric vehicle. During the driving of the vehicle, the powertrain integrated controller will interpret the driver's driving intention, calculate the torque to be output by the motor, and send a power request to the battery management system. The battery efficiency and SOC data are collected at different discharge powers and fitted to obtain the battery efficiency graph shown in Figure 5. 3) Transmission efficiency model The power loss of the transmission is mainly composed of gear meshing power loss, bearing friction power loss and oil churning power loss. According to the specific structure of a two-speed AMT selected in this paper, the calculation formula of each power loss is as follows. Where: Pc for gear meshing power loss; Ph for gear sliding friction power loss; Pr for gear rolling friction power loss; f(s) for instantaneous friction factor; Fn for tooth surface normal load; Vh(s) for meshing out loss sliding speed; h for elastic power oil film thickness; Vg for average rolling speed; b for gear effective tooth width; β for gear indexing circle helix angle. Where:P is the bearing friction loss power;M is the SKF model bearing friction torque;n is the bearing rotation speed Where: Pj is the churning loss power; Tchurn is the churning torque 2.2 The optimal economic shifting strategy with optimal system efficiency According to the driving equation of the vehicle, the output power of the vehicle under driving conditions can be obtained, as shown in equation (4). And the input power can be expressed as Combining with equation (4)(5), the efficiency of the whole vehicle system can be obtained as Where: ηsys is the total system efficiency; μ is the road adhesion coefficient; m is the vehicle mass; α is the ramp angle; Cd is the air resistance coefficient; A is the windward area; δ is the mass conversion factor; v is the vehicle speed; ηm and ηb are the motor and battery efficiency respectively; Tm is the motor output torque; Wm is the motor angular speed. Without considering the ramp resistance, it can be obtained from equation (6) that the system efficiency is related to the vehicle speed, acceleration, battery efficiency, motor efficiency and other factors. In order to ensure the highest efficiency of the vehicle system during the driving process, the controller needs to control the vehicle at different accelerator pedal opening and speed to select a reasonable gear to ensure the highest efficiency of the whole vehicle system. Based on the vehicle model in AVL Cruise and the calculation method given above, the system efficiency of 1st and 2nd gears with the battery SOC of 0.9 is calculated respectively, as shown in Figure 6&7. Combining Figs. 6 and 7 gives Fig. 8, from which it can be seen that the system is always most efficient before and after shifting, as long as the shifting is done at the intersection of the two surfaces. Since the vehicle economy is best when the system is most efficient, the best economy upshift curve can be obtained by projecting the intersection of the surfaces in Figure 8 into the acceleration pedal opening-vehicle speed plane, as shown in Figure 9. By analyzing the best economy upshift curve under different SOC, we can get the best economy shift surface of pure electric vehicle under different SOC, as shown in Figure 10. From Figure 10, we can see that the optimal economic upshift curve changes significantly when the battery SOC is below 0.4. The reason is that the battery efficiency decreases dramatically when the battery SOC is too low. 2.3 Optimal power shift strategy Without considering the ramp resistance, equation (4) shows that the higher the acceleration of the vehicle, the higher the driving power. Analyzing the relationship between vehicle acceleration with accelerator pedal opening and vehicle speed in different gears, we can get the acceleration change in each gear as shown in Figure 11 In order to obtain sufficient dynamics, it is necessary to ensure the maximum acceleration before and after shifting, as can be seen from Figure 11: shifting at the intersection of gear and 2nd gear acceleration surfaces can ensure the maximum acceleration before and after shifting. Based on the above principle, the best power upshift curve can be obtained, as shown in Figure 12 Similarly, the change of the optimal power upshift curve with different SOC is analyzed as shown in Figure 13. From Fig. 13, it can be seen that the change of the optimal power upshift curve is not obvious with the change of SOC. 3 Shift strategy switching controller design The best economy and power shift strategies were designed above, but in the actual driving process, power and economy are a pair of conflicting indicators. When the driver pursues the power, if the driver adopts the unreasonable economy shift strategy, it will lead to the reduction of power output at the shift point, which will cause the shift stutter and affect the ride comfort, and vice versa. Therefore, in order to avoid this problem, it is necessary to identify the driver's driving intention and switch a reasonable gearshift strategy. 3.1 Driving Intent Recognition The driver model calculates the acceleration or brake pedal opening based on the difference between the current driving state and the desired state of the vehicle, so the driver's driving intentions can be inferred from the accelerator pedal opening and its change rate combined with the current vehicle speed. In order to quantify the driver's driving intention, the comprehensive performance index E and the power demand factor are proposed, and the specific calculation method is as follows: Where: Cb is the average power consumption of 100 km after normalization of the scale; ta is the acceleration time to reach the desired speed after normalization of the scale. The larger the power demand factor, the more power the driver needs, and the best power shift strategy should be chosen to obtain a shorter acceleration time. If the power demand factor is smaller, it means the driver pursues more economy, so the best economy shift strategy should be chosen to get smaller average 100km electricity consumption. By analyzing the accelerator pedal opening and its change rate, the reasonable power demand factor is inferred, and the corresponding shift strategy is selected so that the comprehensive performance index is minimized, which means the best shift strategy is selected. 3.2 Determination of power demand factor based on fuzzy theory The determination of the power factor involves many factors and complex nonlinear relationships, and it is difficult to establish an accurate mathematical model. Fuzzy control theory does not rely on accurate data models and is robust enough to accurately derive a reasonable power demand factor based on the input. In this paper, the accelerator pedal opening and its change rate are selected as the input of the fuzzy controller, and the power demand factor increment is selected as the output of the fuzzy controller, and the structure of the system is shown in Figure 14. As can be seen from Figure 14: When the power demand factor is optimized by the fuzzy controller to be less than 0.5, the switching controller considers that the current driving intention is to obtain better economy, and vice versa, the driver needs more power output. The above switching logic can ensure the best overall performance during the driving process. As the vehicle is in braking condition, it needs to recover as much energy as possible and choose the economical downshift strategy. Therefore, in this study, we only design the switchover controller for pure electric vehicles under driving conditions. The relationship between the driver's intention and the accelerator pedal opening and its rate of change is analyzed as follows: when the driver has a stronger power demand, he will press the accelerator pedal, and the larger the accelerator pedal opening, the stronger the driver's power demand at this time, and vice versa. At the same time, the rate of change of the accelerator pedal opening can reflect the urgency of the driver's power needs, the greater the rate of change indicates that the driver urgently needs more power output, and vice versa Combining with the above rules, the fuzzy domain of accelerator pedal opening is 0,6], the fuzzy domain of accelerator pedal opening rate is [-6,6], and the fuzzy domain of power demand factor increment is [-6,6], a reasonable subordinate degree function and fuzzy control rule table are formulated to obtain the fuzzy control surface shown in Figure 15. The incremental power demand factor output from the fuzzy controller is added with the current power demand factor to determine which gearshift strategy to use. When the power demand factor λ≥0.5, the driver needs more power for the vehicle and the best power shift strategy is used, while when λ<0.5, the best economy shift strategy is used. 4 Simulation and test In order to verify the effectiveness of the designed shifting strategy, the control strategy is compared with the conventional shifting strategy based only on the optimal motor efficiency. The simulation parameters are shown in Table 1, the initial SOC value of the battery is set to 0.9, and the NEDC city cycle condition is selected for the simulation. The simulation results are shown in Figures 16 to 19. From the simulation results in Table 2, it can be seen that: compared with the traditional shift strategy, the integrated shift strategy designed in this paper can effectively improve the efficiency of the system, with an average efficiency improvement of 11.19%, battery SOC improvement of about 10.37%, average 100 km electric power consumption reduction of 9.97%, and average acceleration deterioration of about 3.96%. This shows that the integrated shift strategy can effectively improve the economy of pure electric vehicles and extend the range, while ensuring the vehicle dynamics to meet the driver's driving needs. In order to verify the effectiveness and application of the shift strategy, a two-gear AMT test rig as shown in Figure 20 was used. The test results are shown in Figures 21 and 22 From Figs. 21 and 22, it can be seen that although there are some differences between the test data and the simulation data, the trends are more or less the same, and it can be proved that the designed shift strategy is equally effective for the real two-gear AMT. 5 Conclusion 1) The efficiency models of pure electric vehicle power battery, drive motor and transmission were analyzed, and the efficiency trends of the main components of pure electric vehicle and their influencing factors were obtained. 2) By analyzing the variation of system efficiency with accelerator pedal opening and vehicle speed in different gears when SOC is 0.9, the optimal economic shift curve is obtained with the highest system efficiency as the target projection, and then by analyzing the variation of the optimal economic shift curve in different SOC, the optimal economic shift strategy is formulated for each working condition of the vehicle. 3) By analyzing the variation of acceleration with accelerator pedal opening and vehicle speed in different gears, the optimal power shift curve was designed with the goal of maximum acceleration. Similarly, the influence of SOC variation on the optimal dynamics shift curve was analyzed. 4) A power demand factor adjustment controller was designed based on fuzzy theory to predict the power demand of the vehicle by driving behavior and to switch between economic and dynamic shift strategies by combining 100km power consumption and acceleration time as comprehensive performance indexes and taking the accelerator pedal opening and its change rate as input. Through simulation and experiment, it is found that the designed pure electric vehicle shift strategy can greatly improve the economy and extend the range of the vehicle compared with the traditional shift strategy while ensuring the power.

Abstract: China's car ownership continues to increase, new energy vehicles are also gradually promoted in the market, new energy electric vehicles occupy an increasingly large market. In an electric car, the most core part is the motor drive system, the performance of the motor drive system plays the most direct impact on the performance of the whole car, in view of this situation, this paper firstly discusses the specific requirements for the performance of the motor drive system of new energy electric vehicles, and then analyzes the key technology, and analyzes the control of the system and its advantages in detail, hoping that this paper It is hoped that this paper can bring some reference value for the future research of new energy vehicles. Keywords: New energy electric vehicle; motor drive system; performance 1. New energy electric vehicle motor drive system performance requirements The performance of new energy electric vehicles depends largely on the motor control system, power supply system and motor drive system, the motor drive system is the system that provides power to the electric vehicle, is the core part to ensure the normal operation of the electric vehicle, a good motor drive system needs to have the following requirements: First, the cost of the electric vehicle drive system and the price of the internal combustion engine system is similar to no child, the price is relatively low: Second, it needs to have good performance, has a large instantaneous power and a wide range of constant power and starting torque, can quickly achieve acceleration. Second, it needs to have better performance, with larger instantaneous power and wider constant power and start torque, can quickly achieve acceleration, third, wide range of speed regulation, low-speed operation can climb and start, in the constant power area, low torque and have a high speed, so as to ensure that the car on a flat road normal driving, improve the range; fourth, with the best capacity Utilization rate, in a certain environment, can achieve the optimal mechanical efficiency and motor efficiency, effectively increase the use of energy efficiency of electric vehicles, can guarantee the smooth operation of the car in a variety of environments. 2. Analysis of key technologies of new energy vehicle drive motor Power system and drive system together form the power system of new energy vehicles, so the power system is the key part to control the driving range and operating cost of new energy vehicles; the power performance of electric vehicles mainly depends on the drive system, which is composed of controller, drive motor and transmission. Together, the most critical component in the drive system is the drive motor. It can be seen that the drive system is the core component of the car, so improving the performance of the drive system and the power system of new energy vehicles is the key to the effective development of new energy vehicles. 2.1 Drive motor technology At present, DC motor drive system and AC motor drive system are the two electric drive systems applied in new energy vehicles. The drive system of DC motor drive system uses DC motor, also referred to as DC drive system uses DC motor has more advantages, for example, DC motor has better mechanical characteristics, easy speed adjustment and has good performance, easy to control, high timeliness has lower cost and mature technology, etc.. However, DC motor also has some problems to be improved, for example, the brush and commutator of DC motor are wearable parts, which need regular maintenance by human after being worn. The drive system of AC induction motor drive system is AC induction motor, which is also called AC drive system. Compared with DC motors, AC motors are more efficient, reliable, do not require maintenance and easy to cool, and generally have a longer service life. Among various motors, permanent magnet motor has the highest power density. The drive motor of permanent magnet synchronous drive system is composed of brushless DC motor (BLDCM) and three-phase permanent magnet synchronous motor (PMSM), which is smaller in size and lighter in weight, and has higher efficiency and does not require special manpower for maintenance, and has been used in new energy vehicles. The motor structure of switched reluctance motor drive system has higher efficiency, simpler and more reliable than induction motor, the rotor has no winding, which is more suitable for frequent forward and reverse rotation and shock load. The system has been well used in new energy vehicles because of its wide range of speed regulation, large torque at low speed and braking energy feedback. However, the disadvantage of this system is that the vibration noise generated is large. 2.2 Drive motor control technology Drive motor control technology is currently developing towards a drive control system with wide speed range, wide torque variation and improved efficiency of the entire working conditions. DC motor as a drive motor drive system, the driver circuit uses chopper control, AC induction motor control inverter is more complex, on the one hand, compared to the DC drive system, the control of the number of high-power tubes used more, on the other hand, to obtain good speed performance, you need to take the vector control mode, in its inverter in addition to the need to use In addition to the need to use a better performance of the microprocessor, the software used is also more complex. With the rapid development of electronic technology, the inverter technology applied in the AC system is also becoming more and more mature. The permanent magnet brushless synchronous motor can be divided into square wave type permanent magnet brushless DC motor and sine wave type permanent magnet brushless DC motor according to the distribution of the spatial air gap magnetic field. The basic way to regulate the speed of permanent magnet brushless synchronous motor is frequency control, PWM chopper control IGBT inverter is now widely used, in order to further strengthen the control of torque, it is necessary to increase the motor regulation control, so as to slow down the fluctuation of torque. The stator and rotor of the switched reluctance motor (SRM) in the drive system of the new energy vehicle belong to the convex pole structure, which has a relatively simple control device and only needs to install the excitation winding of each phase at the convex end of the stator, and no winding is needed on top of the rotor. However, the torque pulsation is large and the noise generated is high. The inverter and motor lead wires are determined by virtue of the number of stator cams. At present, it is not widely used in practice, but with the improvement of technology, it has been gradually applied in new energy vehicles. 3. New energy electric vehicle motor drive control system A good drive system can ensure the smooth operation of new energy electric vehicles, so in the process of manufacturing new energy electric vehicles need to be matched with a good drive control unit, so as to ensure that the electric vehicles have a good operating effect. Vector control (VC) and direct torque control (DTC) are the more common combinations of units used for drive control, which can ensure the smooth operation of the car in the process of control and effectively avoid errors. Therefore to record the zero number of vector control and direct torque control, comparing vector control and direct torque control, from the data specifications, direct torque control is smoother than mass control: from the power device switching frequency point of view, vector control is more advantageous: from the analysis of system complexity, vector control and direct torque control are poorly, vector control performs well at low system speeds, and Direct torque control is not smooth enough, vector control is smooth and favorable in system starting performance, through direct torque control vehicle will cause a larger wear and tear on the vehicle, vector control has a smaller system torque pulse compared to direct torque control, and vector control has a wider range of speed control than direct torque control. In summary, compared with direct torque control, vector control has better performance in low-speed performance, speed range and starting performance. With the implementation of some national environmental protection policies, the special research on electric vehicle controller and the research on the safety hazards involved in the key parts of electric vehicles have been gradually developed in the direction of systematization. However, the focus of the research is not accurate enough, for the core of the electric vehicle drive control center research is not deep enough, specifications and operating temperature are not within the specified range, beyond the standard limit, the system is not intelligent enough, the drive system can not be self-test for faults reduce the safety performance of electric vehicles. 4. Advantages of new energy electric vehicle control system The energy of the new energy electric vehicle mainly comes from the electric motor. The excellent performance of the new energy electric vehicle motor control system can provide a better operating condition for the electric vehicle. In complex road conditions and bad weather, the vehicle needs to have high performance. In the process of driving the vehicle, the driver manually operates the vehicle in order to change the operating status of the vehicle. The vehicle controller receives the driver's control signals such as accelerating throttle, braking, etc., and then starts the vehicle control system. After the motor controller receives the command, it sends the operation information to the drive motor and realizes the control of the steering and speed of the drive motor by changing the voltage, current and frequency of the power supply. During the driving process of the vehicle, the positive rotation of the motor can keep the direction of the vehicle forward, and the reverse rotation of the motor is to prepare for reversing. When the vehicle decelerates, the current generated by the sub-torque of the drive motor needs to be integrated and shunted for processing to charge the power battery pack, and then the received motor speed information is fed back to the vehicle instrumentation to ensure the real-time detection of the motor running status, and in order to improve the precision of the control, the motor needs to be Various data integration analysis, and constantly adjust therefore, as the core components of the electric vehicle motor control system, need to meet the following three advantages: First, the motor control system can meet the frequent start and stop, in the more severe weather and complex environment, electric vehicles in the human start and stop operation can still maintain a stable running state. Second, upgrade the indicators and control of electric vehicles, in order to maximize the value of the tram energy, need to strengthen the durability of the battery, and make the components have good compatibility. Thirdly, after a long period of complicated and frequent operation, the motor still has strong sensitivity, and when the temperature difference of the external environment is in the range of 30-130C, the motor can still operate effectively. The core components of a new energy electric vehicle are the motor and the control system, both of which are electronic components with extremely advanced and complex technologies. The performance of the motor and control system is directly related to the safety performance of the electric vehicle. At present, there are still some technical problems to be solved in the research of driving range and energy of new energy vehicles, but with the development of human technology to a certain level, these technical problems will be solved in the near future. Under the situation that the earth's environment is polluted and the earth's energy is decreasing, domestic and foreign countries are on the same level of new energy vehicle R&D and manufacturing, but in China, there are energy advantages and policy support and encouragement, and the resources used to manufacture batteries and motors for new energy electric vehicles are more abundant in China, in addition, the country is vigorously supporting new energy electric vehicles, and some industries are actively carrying out In addition, the country is vigorously supporting new energy electric vehicles, and some industries are actively upgrading industrial research and development, constantly improving the standardization of drive chips, motor control chips and motor control systems, and under the dedicated research of the industry, we believe that China's new energy electric vehicles will achieve rapid development.

Contents 1 Introduction of reducer 2 Testing process 3 Test disassembly and analysis 4 Conclusion The reducer is an important part of the transmission components in the new energy vehicle, which can transmit the output torque of the motor to the output shaft through the reducer to drive the vehicle tires by increasing the torque. The transmission performance of the reducer directly affects the efficiency, smoothness and driving power of the vehicle. The maximum transmission torque of the reducer is directly influenced by its body material, structural strength and gear performance. The maximum static torque of the reducer is analyzed through tests to ensure the reliable operation of the reducer in operation. A new energy vehicle parallel shaft reducer was studied, and the static torque test was conducted by increasing the input torque at a constant speed until abnormal failure occurred, and the failure principle was analyzed. The results show that the static torsional safety factor of the gearbox is 2.56, which meets the design requirements of the gearbox half-shaft gear and planetary gear metallographic and hardness are in accordance with the design requirements. 1 Introduction of the reducer The object of the test is a parallel shaft reducer for the secondary drive of a new energy passenger car, as shown in Figure 1. The input end is a splined shaft with input, and the output end is a differential gear connecting the two half shafts for output support bearings are ball bearings. The reducer design rated torque, rated speed and other parameters are shown in Table 1 At the beginning of the design, the strength and life of the components were checked, and they were all within the design range, where the static torsional strength of each key component was above 2.5 times the maximum input torque and some components were above 3 times. 2. Test procedure 2.1 Test method The input end of the reducer is connected to the drive motor through the adapter and universal coupling, and the spline of the differential output is connected to the two output half-shafts and fixed to the tooling base, as shown in Figure 2. 2.2 Preliminary analysis of the test The gear teeth are subjected to the squeezing force of the bearing, the bending force at the engagement, the bending force of the drive shaft, the squeezing force of the bearing at the drive shaft, and the bending stress of the bevel gear at the engagement inside the differential housing during the static torsion test. Therefore, the static torsion test continuous loading can lead to the failure of one or several different parts of different parts of the test in the range of 125.1 ° drive shaft rotation produced 3 times the peak torque and accompanied by 3 times the sound of collapse Therefore, it can be judged that at least 3 parts should have broken or failed 3. Test disassembly and analysis 3.1 Disassembly and inspection After the reducer is removed from the test bench, the input shaft can rotate freely and drive the differential shaft to rotate, and the two output half shafts of the differential can rotate at the same speed in the same direction, but cannot carry out differential speed, so the preliminary judgment is that the gear teeth of the reducer drive gear have not failed and broken, and the failure site is inside the differential. Disassembly and inspection found that there is no crack at the root of the transmission gear teeth, and there is no obvious extrusion marks at the tooth surface involved in the engagement. The bearings rotated smoothly without any obvious abnormalities such as stalling No indentation and deformation in the bearing holes of the case No cracks and deformation of the drive shaft The transmission shaft is under static torsion, which means the transmission gear, bearing, case and strength of the gearbox are sufficient. No obvious deformation and failure of the differential gear housing, as shown in Figure 4 Disassemble the differential gear and find that the teeth of the two half-shaft gears of the differential gear have cracks, and the differential gears are subjected to fluorescent magnetic particle inspection and flaw detection. There were two cracks in the half-shaft gear I, which was located at the position of the two planetary gears, and the two cracks at the root of the teeth at the crack ① were very large, and the cracks were clearly visible, and the cracks were cracked along the root of the gear teeth, and there were also cracks on the tooth end face and tooth side as shown in Figure 5 The crack at ② is small and difficult to find with the naked eye, and the crack exists at the root and side of the two teeth, as shown in Figure 6. There are also two cracks in the half shaft gears, which are also located at the meshing position with the two planetary gears, and the two cracks at the root of the teeth at crack ① are obvious and visible to the naked eye, and there is also a crack on the tooth end face, as shown in Figure 7. Crack ② is more obvious and visible to the naked eye, and there are cracks on the tooth root, tooth end face and tooth side as shown in Figure 8 The planetary gear has a crack, the crack is not obvious, the naked eye can not see clearly under the fluorescent magnetic particle inspection can be found, the crack is on the tooth end face, as shown in Figure 9 Cracks in descending order: half shaft gear I crack ① half shaft gear work crack ① half shaft gear work crack ②, half shaft gear I crack ②, planetary gear I wheel crack 3.2 Failure analysis 3.2 Cause analysis The cracks produced on the tooth surface and tooth root are bending fracture cracks In the static torsion test, the differential gear is meshed with the half-shaft gear through its planetary gear, and the torque is transmitted to the half-shaft gear and then to the fixed tooling. Therefore, in this process, the gear teeth at the mesh are mainly subjected to bending stress, thus the gear teeth at the mesh are prone to bending fracture The reason for 3 torque peaks in static torque loading is that the differential bevel wheel has more than 4 pairs of bevel gears involved in each mesh. The first time the torque peak is reached, the root of one of the half-shaft gear teeth involved in the mesh breaks off and the drive torque is then unloaded The second reloading of the first cracked half-shaft gear gear teeth under load continues to expand at the cracked place while squeezing the other three gears until one of the gear teeth collapse, followed by drive torque unloading the third time the same principle as the second time, squeezing the other two gears until the third gear teeth collapse 3.2.2 Fracture analysis The differential half-shaft gear and planetary gear materials are 20CrMo carburized fire steel, surface hardness requirements for 58 ~ 62HRC, the core hardness requirements for 30 ~ 42HRC Anatomical analysis, the test results are shown in Table 2, all meet the design requirements The most serious failure of the half-shaft gear I crack ① ((Figure 5) for fracture analysis of the root crack crack cracking serious existence of five cracks crack at the root are not obvious plastic deformation, two of which are located in the root of the tooth, a crack is located near the transition of the inner spline tooth root, another crack is located in the tooth root transition of the outer edge of the tooth groove, the outer edge of the tooth groove thickness is thin, especially with the minimum thickness of the tooth transition. The other three smaller cracks exist on the tooth end face and tooth side face One of the cracks with a larger opening at the transition of the tooth root on the outer edge of the tooth groove was cut and removed manually to open it, and the macroscopic morphology of the open fracture is shown in Figure 10, the overall fracture is silvery gray metallic luster, there are obvious radial stripes, and the direction of the radial stripes can be seen from the chamfer of the transition between the outer edge of the tooth groove and the gear teeth, where the thickness is the thinnest Figure 11-14 shows the crack source Figure 13 (i.e. Figure 11 interrupted I area) microscopic morphology along the crystal morphology, fracture source at the chamfer surface machining marks deeper, no slag, sparse and old day crack defect characteristics. Figure 14 (i.e. Figure 11 fracture II area) microscopic morphology, dominated by tough nest morphology Cut the complete tooth groove outer edge and the chamfer of the gear tooth transition cross-sectional specimens for metallographic examination metallographic as shown in Figure 15, according to GB/T10561-2005 assessment of its non-metallic inclusions level: A1.0, D0.5 indicates that its material purity is good In summary, the gear crack has the characteristics of overload brittle cracking, the crack source is located in the structure of the stress concentration of the outer edge of the tooth groove and the chamfer of the tooth transition, the fracture source is not seen at the slag sparse and old crack defects. 3.2.3 Safety factor The static torsional safety factor of the reducer is S = M/ Mmax = 667 /260 = 2.56 where:Mmax is the maximum input torque of the reducer M is the torque of the reducer in case of failure. According to QC/T1022-2015 "Technical conditions for pure electric passenger car reducer assembly" 5.2.9, the static torsional strength reserve factor should be not less than 2.5, and the safety factor meets the design requirements 4. Conclusion (1)The gear inside the differential in the static torsion test broke apart and failed, and the rest of the parts were normal. (2) The differential half-shaft, gear planetary gear metallographic and hardness are in accordance with the design requirements, the fracture fracture is brittle fracture. (3)The torque safety factor of the reducer in static torsion test is 2.56, which meets the design requirements. Through the static torque test and analysis of the reducer, the weak points of the reducer are reflected, which provide the basis for further improvement of the design and performance of the product.

Preface ■ Traditional automobile engines must have idle speed to meet drive requirements; ■ There must be a clutch or torque converter to meet the starting requirements; ■ The engine needs sufficient backup power to meet the acceleration requirements; ■ Conventional powertrains cannot recover braking energy. Definition of electric transmission >EVT( Electrically Variable Transmission) Electric drive transmission is a mechanical energy-electrical energy-mechanical energy conversion device with two mechanical interfaces; Input and output interface, an electrical interface connected to the battery, typical hybrid vehicle drivetrain structure, output shaft output torque and power are desirable from the engine can also be taken from the battery. Type of an electric transmission Basic concepts of planetary gears Planetary train angular velocity simulation lever method Planetary gear train torque simulation lever method Relationship between planetary gear train and lever method Parallel Hybrid.Serial Hybrid.Power Split (Dual) Hybrid Serial Hybrid ICE- Internal Combustion Engine EGM- Generator EDU- Drive Motor GCU- Generator Controller BCU- Battery Controller Battery- Power Battery SDU - Safety Protection Unit CEU- Motor Controller ----- DC, High Voltage ----- AC, High Voltage ----- Control Signal, Low Voltage Features ● No need to use gearbox, simple structure, simple control algorithm -High efficiency with small internal combustion engines (always working on the best fuel curve) No gear shift shock Two electric drive systems are required ● High power of electric motor ● High battery power, high weight and high cost ● Large battery charge/discharge depth and short life span BAE SYSTEMS Partnership with Orion Bus 325 Orion VII 12m low-floor buses in operation in New York, 500 new orders Fuel savings of 31% (diesel) - 50% (gas) 110 kW motor, Hawkwer advanced lead-acid batteries $500K/bus;$100K>CNG;$150K>Diesel ISE Corporation 170 /288 kW bi-directional motor; 300 kg Bidirectional inverter; 72 kg ■ Cummins ISB engine ▪ Cobasys 576-240 NiMH battery, 300 kg Three vehicles in test operation in New Jersey, 20% more fuel efficient than conventional vehicles in best condition ◆ 150/240kW, or 65/120kW induction AC motor; 160/290kg ◆ 50kW engine/motor unit ◆ 120/240kW,250-425V Input inverter ◆ Cummins ISB engine Used with various batteries Parallel Hybrid 1.Front parallel structure Features ● Only one set of electric drive system is required ● Low motor power, low battery power, light weight and low cost ● Reduces the power of internal combustion engine ● Multiple operation modes such as pure electric, pure engine and hybrid can be realized, and reliability High reliability ● Complex structure and control algorithm 2. Rear-mounted parallel structure Features ● Can be modified and retrofitted to existing vehicles ● Only one set of electric motor and control device is needed ● High motor torque, high battery power, high weight and high cost Eaton Corporation 26 /44 kW permanent magnet motors; Various electronically controlled engines Lithium-manganese battery Automatic mechanical gearbox Dry automatic clutch Mitsubishi Fuso ◆ 35 kW permanent magnet motor; 92 kW engine ◆ Lithium-manganese battery ◆ Automatic mechanical transmission, dry automatic clutch Enova Corporation ◆ 60-90 kW induction type AC motor; Various different batteries have been used Power Split (Dual) Hybrid ◎ Stepless variable speed, no gear shift shock ●Two sets of electric drive system are needed ●High motor power ●High battery power, high weight and high cost ●High development cost due to special hybrid drive unit required ●Complex structure and control algorithm Allison Two 100/160 kW induction motors; ▪ 280-330 hp engine 600V 200kW NiMH battery 430kg Stepless variable speed function ▪ 60′, 50' and 40′ passenger cars in partnership with New Flyer 325 units in Seattle, 1732 units in Washington and Philadelphia Planetary gear power splitting is the best solution for deep hybrids Deep hybrids dominate the world's new energy vehicles, accounting for 90% of global sales of global sales 100% of deep hybrid solutions use planetary gear power shunts Global market for deep hybrids continues to grow Planetary gear power splitting technology is a gap in China's automotive industry Global market sales of hybrid cars (million units) Power Transmission Theory Single- and dual-flow transmission theory Electromechanical coupling system Torque coupling Rotational speed coupling Power coupling ● Output torque and speed are the linear sum of engine and motor torque and speed, respectively, so that engine torque and speed are controllable. Rotational speed coupling method K is the ratio of planetary gear teeth, n is the speed, T is the torque Characteristics: The load torque determines the torque of the power source Single Planetary Row Speed Coupling System Compact planetary row hybrid driveline (CHPTD) Compact planetary row hybrid driveline (CHPTD) Torque coupling method K is the ratio of planetary gear teeth, n is the speed, T is the torque Characteristics: The speed of the load determines the speed of the power source Honda Parallel Hybrid System (IMA) work mode Single row planetary gear coupling Double-row planetary gear coupling Dual rotor motor coupling Single-mode hybrid Hybrid infinitely variable speed control system optimization working principle 1. For any output torque and speed, within a certain range, you can configure any The speed and torque of the engine; 2. At a specific working point, considering the charging and discharging efficiency of the battery and the efficiency of the motor, the best point of fuel consumption can be found and the engine can be optimized. To find the best point of fuel consumption and achieve engine optimization; 3. In the hybrid working condition, when the battery is in balance, there is always a motor, a motor drive, there will be efficiency losses, affecting the efficiency of the system; but consider Optimization of the engine working condition, can get better economy than the traditional car; 4. control completely torque control mode, for a specific speed output torque demand, according to the system optimization strategy, the distribution of the calculation of the engine torque, and the torque of the two motors. Dual-mode hybrid

1. Optimisation of transmission ratios and shift quality of two-speed automatic transmissions for pure electric vehicles Summary: The transmission is a key component of the vehicle drive train, which directly affects the performance of the vehicle. In order to improve the efficiency of the electric vehicle drive motor, the fixed speed ratio electric vehicle is modified and a two-speed transmission ratio scheme is adopted to improve the efficiency of the drive motor, which in turn improves the overall vehicle power performance and economic performance. The study focuses on the optimisation of the transmission ratio and shift quality of a two-speed automatic transmission for pure electric vehicles. 1.The basic parameters of the vehicle The electric vehicle was studied based on a traditional microcar, retaining the original suspension system, using lithium manganese acid batteries for the power battery and permanent magnet synchronous motors for the drive motor. After comprehensive research, the vehicle parameters are: full load mass 1 350 m/kg, mechanical transmission efficiency 0.9, tyre rolling radius 0.258 r/min, wind area 1.868 A/m2, air resistance coefficient 0.31. According to the national standard GB/T 28382-2012 standards and market positioning, the vehicle dynamics indicators are as follows: 30 min maximum speed ≥ 80 km / h. Maximum climbing speed ≥ 20%, climbing speed of 4% slope ≥ 60 km/h, climbing speed of 12% slope ≥ 30 km/h, working condition method driving mileage ≥ 100 km. 2.Driving motor parameters are determined When selecting the motor, it is important to ensure that the motor works at maximum efficiency and also to consider the peak discharge rate of the battery pack. 2.1 Calculation of the power of the drive motor at maximum speed At the highest speed on a horizontal road, ignoring the acceleration resistance, let the wind speed be 0, then the output power of the motor is P1 is the drive power at maximum speed; ηt is the mechanical transmission efficiency; mg is the fully loaded mass of the vehicle; f(u) is the rolling resistance coefficient; umax is the maximum vehicle speed; Cd is the air resistance coefficient; A is the windward area. where f (u) = 1.2 (0.009 8 + 0.002 5 [u/(100 km/h)] + 0.0004 [u/(100 km/h)]4). According to the actual demand and international standards, choose 100 km/h speed, according to the formula (2), the calculation result is 0.015 24, substitute into the formula (1), the calculation result is P1 = 13.2 kW. if the speed of the vehicle in line with the national standard of not less than 85 km/h, then the motor power can also choose a smaller.. 2.2 Calculation of the power of the drive motor at maximum climbing The power required for hill climbing is calculated by ignoring the air resistance power and acceleration resistance power, then the motor output power can be calculated as f (u) = 0.012 7, according to the formula (3) can be calculated as P2 = 26 kW. P2 is the maximum climbing driving power. i is the degree of climbing; ua is the minimum vehicle speed when climbing. 2.3 Acceleration performance calculation of the peak power of the drive motor Assuming a wind speed of 0, the maximum power output of the electric vehicle on a horizontal road is located at the end of the acceleration process of the whole vehicle. P3 is the maximum power required at the end moment of uniform acceleration; ta is the uniform acceleration time; ua is the speed at the end of uniform acceleration. According to GB/T 28382-2012 standard, ta is 10 s, and P3=21.3 kW can be calculated according to equation (2) and (4). According to equation (1), the rated power of the motor is 15 kW, and the peak power of the motor is 30 kW according to equation (3) and (4). In order to meet the cost factor and the actual demand, the motor is finally selected with a rated power of 15 kW and a peak power of 30 kW. 3. The traditional ratio of the driveline is determined by comparing the power performance of the transmission using the following ratios without changes in driving conditions and motor characteristics, to achieve optimisation of the transmission ratio and to improve the shift quality. 3.1 Single ratio power performance In order to take into account the maximum climbing degree and the maximum speed, the fixed transmission ratio is chosen to be 6.963, then its resistance and power balance, 85 km/h is the maximum speed achieved, 12% slope is the maximum slope, in order to make the climbing performance to be satisfied, the peak power of the motor is increased to 45 kW and the speed is increased to 9 000 r/min in order to achieve. The main problems in this case are the need to increase the battery discharge power, the lubricity of the gearbox and the impact on the reversal of the gearbox input shaft in reverse gear. 3.2 Power performance of the two gear ratios If the power input of the motor is the same, the high gear ratio and the low gear ratio of the two gear transmissions are 6.5 and 10 respectively. 90 km/h is the maximum speed that can be achieved, while the maximum climbing gradient does not reach 20% and can only be approached. Therefore, a higher power output from the drive motor is required to achieve higher speeds and climbing degrees, which requires the performance of the battery to be improved as well. 3.3 Power performance of a five-speed transmission ratio With a 15 kW power rating, the maximum and minimum ratios of the five-speed transmission are 3.538 and 0.78 respectively, with a main reduction ratio of 3.765 and a reverse gear ratio of 3.454. 96 km/h is the maximum speed that can be achieved with the five-speed transmission at the 15 kW power rating, and the maximum climbing gradient is more than 20%, so the power performance is effectively met. If the minimum standard speed of 85 km/h is required, the maximum and minimum ratios of the five-speed transmission are 5.494 and 1.033 respectively, with a main reduction ratio of 4.314 and a reverse gear ratio of 3.583. At 11 kW rated power, the vehicle can reach a maximum speed of 85 km/h and a maximum gradient of 20%. With two gears, the battery discharge power requirement is 30 kW, with a discharge multiplier of 1.28; with five gears, the battery only needs to provide 15 kW of discharge power to meet the power performance, with a discharge multiplier of 0.64. Therefore, the battery performance requirements are significantly reduced when using a five-speed transmission. 3. 4 Comparison of 3 types of transmission Based on the above analysis, the maximum speed and the maximum hill climb for the three transmissions are shown in Table 1 if the motor is selected with a 15 kW power rating. With a 15 kW motor and a five-speed transmission, the maximum speed and the maximum gradient can be achieved. In terms of energy consumption, under the same conditions, the minimum power output of the five-speed transmission is 11 kW, the minimum output of the two-speed transmission is 15 kW and the single-speed transmission is 45 kW. In terms of energy consumption, the five-speed transmission is the lowest. 3. Conclusion This study shows that the two-speed automatic transmission ratio of pure electric vehicles is better than the single-speed transmission ratio, but slightly worse than the five-speed transmission ratio. Therefore, for pure electric vehicles with two-speed transmission, in order to improve the traditional ratio and achieve the maximum speed and the maximum climbing degree, the transmission can be improved, using five-speed transmission, which can achieve the improvement of vehicle performance. At this stage, five-speed transmissions have already achieved industrial development, while the results of two-speed transmission development is obviously not obvious, so five-speed transmissions can be directly applied to existing technologies and achievements, to achieve a reduction in research and development costs, while five-speed transmissions on the battery, motor requirements are not high, is the main direction of future electric vehicle development.

Contents 1. Introduction 2. Introduction to the drive motor in new energy vehicles 3. Needs of motor function in new energy vehicles 4. Application of electric motors in new energy vehicles 5. Key drive motor systems in new energy vehicles 6. Conclusion 1. Introduction The emergence of new energy vehicles breaks the rules of traditional car energy supply, replacing the power source engine in traditional cars with an electric motor, and converting the car electric energy generated by the motor into mechanical kinetic energy to make the tires roll according to the law of conservation of energy, so that new energy vehicles can run normally. The motor is a very important part of the new energy vehicle, all the energy needed to run the new energy vehicle is from the motor. There are many different types of motors, and the one we use for new energy vehicles is the drive motor system. In today's society, the market share of new energy vehicles is increasing year by year, and the power source of new energy vehicles relies on electric motors to provide electric energy for them. New energy vehicles not only meet the requirements of consumers for cars and travel, but also meet the environmental protection theme of today's times. This paper summarizes what kind of function of electric motor is needed for new energy vehicles, discusses how electric motor works in new energy vehicles, and studies the role of key drive motor systems in the use of new energy vehicles so that electric motor can be scientifically used in new energy vehicles to achieve the requirements of energy saving and environmental protection. 2. Introduction to the drive motor in new energy vehicles 2.1 Drive motor function introduction The drive motor is a three-phase permanent magnet synchronous motor, which is used as the drive of the pure electric car and is installed in the front compartment. These motors have the characteristics of simple structure, small size, light weight and high efficiency. Under the control of the controller, the motor can work in a wide range of speed to meet the operating conditions of the pure electric car: the motor has a built-in resolver for detecting the rotor speed and position to achieve vector control of the motor; the motor cooling method is liquid-cooled structure. 2.2 Technical parameters of the drive motor (Table 1) 2.3 Motor controller function introduction (DC input, three-phase AC output) The main functions of the motor controller are: 1 control of the motor operation in electric mode or power generation mode. 2 torque control of the motor drive system. 3 protection functions such as over temperature, over current and over voltage. 4 with CAN communication and diagnosis function. 2.4 Technical parameters of the functional part of the motor controller (Table 2) 3. Needs of motor function in new energy vehicles The specific motor of the new energy vehicle is normally activated and driven on the premise that the driver should also consider whether the driver is comfortable when driving the new energy vehicle, to help the new energy vehicle better adapt to the driving environment, and to achieve the effect that the new energy vehicle only needs to be charged once in the case of long-term driving. Therefore, new energy vehicles have special requirements in terms of motor-related functions, which are elaborated below. First, the specific motor of new energy vehicles has a higher level of efficiency standards and power density standards. In the new energy vehicle, the rotation speed range of the motor is relatively large, and the torque range has a high efficiency, so that the power loss will be greatly reduced, and after a one-time charge, the total distance of the new energy vehicle will have a substantial increase in continuous driving. Second, for new energy vehicles, the motor needs to have a wide range when adjusting speed. In the new energy vehicle, constant torque and constant power are necessary for the specific motor to ensure that the new energy vehicle can ensure a high constant torque even at a slower driving speed, so that the new energy vehicle can be driven uphill under heavy load to ensure that the speed of the new energy vehicle in use can be quickly increased to maintain the enabling efficiency of the new energy vehicle; when the new energy vehicle is driving at a faster speed, the corresponding motor power can be more stable. The corresponding motor power can be sent to the inside from the outside more steadily, and there are more options for speed adaptation. At this time, on a relatively flat road, the new energy vehicle can maintain high speed, and the new energy vehicle can also overtake quickly. Third, the safety of the motor that ensures the normal operation of the new energy vehicle is higher. In any case, the motor should guarantee the reliability of the new energy vehicle driving, are required to ensure that the new energy vehicle running safety is better, and has the function of resistance to shock and vibration. Fourth, to maintain the new energy vehicle specific motor related instantaneous power is relatively high, maintain the overload capacity is relatively large. It is necessary to maintain the existence of multiple overload function of the new energy vehicle, which can make the new energy vehicle able to increase the running speed faster and meet the higher slope running requirements. Fifth, in order to enhance the comfort of using new energy vehicles, the space utilization rate of new energy vehicles needs to be continuously improved, and the weight of new energy vehicles should be reduced in order to make the new energy vehicles rotate more efficiently. As a result, the shell of the motor should be made of lighter metal, the mass of the motor will be smaller and reduce the space occupied by the motor. Sixth, in line with the premise of new energy vehicles on the motor-related needs, the new energy vehicle motor voltage should be as high as possible, to minimize the cost of converting DC power into fixed-frequency fixed-voltage or frequency-regulated AC power converter, at the same time, to do a good job of safety, set up high voltage protection devices to enhance the safety of motor use. Seventh, for new energy vehicles, the corresponding motor needs to improve the braking regeneration efficiency, new energy braking conditions to be reflected in the case of low-speed driving, and the power energy collected into the battery, so that new energy vehicles can aptly use the power energy to meet the requirements of environmental protection. Eighth, the motor of new energy vehicles can better cope with a variety of operating situations. The motor for new energy vehicles needs to have high heat and moisture resistance, so that it can work normally under poor environment when driving and better cope with different operating conditions. Ninth, the motor for new energy vehicle operation also needs other functions. 1. that the motors can be mass produced. 2. the motor should be operable in terms of operation and repair, one being simple and easy to operate and the other being low cost of maintenance. 3. the motor is kept low in operation and does not produce noise. 4. the structure of the motor is relatively simple and uncomplicated. 4. Application of electric motors in new energy vehicles 4.1 New energy vehicle engine motor application New energy vehicles have changed the traditional driving method, and its energy uses electricity, replacing the former fuel oil, which can increase the use of renewable energy and achieve the effect of protecting the ecological environment. In order to change the method of driving the car with fuel, the engine of the new energy car should be changed from fuel to electric motor. The motor replaces the internal combustion engine to start the new energy vehicle, and the motor can smoothly use the mechanical energy to start the new energy vehicle. In this way, new energy vehicles work more effectively and meet the purpose of protecting ecology and saving resources. 4.2 Application of electric motor of new energy vehicle parts With the development of science and technology, the operation method of new energy vehicles has been improved, and the manual operation method has been improved to the automatic operation method. The improvement of this operation method is reflected in the following points: the ability to use the motor to retract and control the rearview mirror of the new energy vehicle; the ability to use the motor to control the windshield wiper and locking system of the new energy vehicle; the ability to use the motor to raise or lower the window of the new energy vehicle. First, the application of electric motors in the mirror operating system of new energy vehicles can improve the manual control method to an automatic operation method. On the one hand, the driver of a new energy vehicle can focus on driving without manually adjusting the rear view mirror, and on the other hand, he can quickly understand the situation of the car behind him, which increases the safety of driving and avoids traffic accidents. Second, the motor can be applied to the new energy vehicle wiper and locking system. In the process of driving new energy vehicles, once someone will unintentionally open the door, it will cause great security risks. To address this potential hazard, the locking setup allows the driver to control all the doors in the vehicle to open or close them. The locking system greatly reduces the incidence of traffic accidents caused by accidental door opening, reducing the safety risks of vehicle operation. The motor provides power support for the locking setting, which is an important protection device for the smooth and safe operation of new energy vehicles. Third, the motor can be applied to the window glass manipulation system of new energy vehicles. The window glass of the car used to be controlled manually, which more or less distracted the car driver and increased the danger of driving. The electric motor and reducer can improve this situation and realize the automatic rising and falling of the window glass of new energy vehicles. 4.3 Application of electric motor in the chassis of new energy vehicles The motor application of the chassis of new energy vehicles mainly includes the following aspects: first, the motor is applied to power steering; second, the motor is applied to avoid wheel locking. The car relies on electric power for power steering. Traditional cars rely on battery power to complete power steering, the energy supply in this way is relatively unstable and requires constant battery replacement, once the power is exhausted, it will bring unnecessary trouble to the driver. In contrast, new energy vehicles can use electric motors to provide energy for power steering. According to the size of the electric motor power and the corresponding torque state, new energy vehicles can adjust their own steering and choose the rate of steering. Wheel lock is a phenomenon in which the brake clamps the tire, and the tire slides relative to the ground because there is no relative motion of the tire to the brake. Wheel locking will have the following consequences: greatly increase the degree of tire loss; increase the danger factor of the car driving, once the wheel locking, the possibility of sideslip, tailing, sharp turn is greatly increased. Therefore, the prevention of wheel locking is an important issue in the operation of new energy vehicles. New energy vehicles can use electric motors to prevent wheel locking and reduce the danger factor of the car in operation, the specific operation method is to install electric sensors on each wheel to detect the rotation speed of the wheel, always grasp the situation of the tire, once the phenomenon of wheel locking is found, it will quickly feedback to the driver and the relative vehicle parts. 5. Key drive motor systems in new energy vehicles 5.1 Specific applications of permanent magnet synchronous motors in new energy vehicles Rectangular wave type brushless DC motor and sinusoidal type permanent magnet synchronous motor are the two common motors of permanent magnet synchronous motor in new energy vehicles. The advantage of rectangular wave brushless DC motor is that it is more stable, not disturbed by electromagnetic wave, no commutation spark, and its output is not easy to produce fluctuation, these characteristics determine the rectangular wave brushless DC motor can be used for a long time. Most people choose to use the rectangular wave brushless DC motor in new energy vehicles because of its high efficiency and stability. Rectangular wave brushless DC motor also contains some disadvantages, its production cost is relatively high, because the permanent magnet in the rectangular wave brushless DC motor system is expensive, and the whole system is relatively messy and complicated. How to simplify the operating system of the future rectangular wave brushless DC motor and how to reduce its production cost are the urgent problems that researchers need to study and solve. 5.2 AC induction drive in new energy vehicles The specific application of the motor AC induction drive motor system corresponding to the motor is generally three-phase asynchronous motor. The advantage of three-phase induction motor is that it is easy to control and the specific internal structure is relatively simple. The operating system of three-phase induction motors is relatively smooth, the use of time can be maintained for a longer period of time, the frequency of repair and maintenance can be relatively low, which reduces the cost of use, the use of three-phase induction motors is relatively good, and other types of motors for comparison, its performance value and price value ratio is more reasonable. The disadvantage of three-phase asynchronous motor is that it requires more power, and the power saved in the new energy vehicle cannot fully maintain the operation of the three-phase asynchronous motor, so it is difficult for the new energy vehicle to completely rely on the three-phase asynchronous motor to complete long-distance driving. Accordingly, the three-phase asynchronous motor requires a large amount of electricity, which also raises its cost of use. Three-phase asynchronous motors should maintain smooth induction motor efficacy when applied to new energy vehicles to prevent shortening the effective use time of three-phase asynchronous motors. Centralized motor drive and conversion of internal combustion engine to electric form are two common ways of AC induction drive motors in new energy vehicles. The cost and price of the centralized motor can be grasped, but the disadvantage is that it is not easy to be produced in large quantities. 6. Conclusion In summary, the new energy vehicle motor function has a multi-faceted, all-round needs, by exploring the specific use of new energy vehicle motor, we can draw the following conclusions: motor for new energy vehicle engine, parts, chassis, has a high practical value; commonly used in the new energy vehicle key drive motor system is permanent magnet synchronous drive motor system, AC induction drive motor system, etc. The use of electric motors in new energy vehicles can enhance the safety of new energy vehicle operation, reduce the consumption of non-renewable energy, and meet the requirements of maintaining the ecological environment in line with the environmental protection theme of the current era.

Contents 1. Preface 2. Carbon Neutrality Targets for New Energy Vehicle Technology Development 3. Conclusion 1. Preface Carbon neutrality targets will have a significant impact on global politics, economy and society, and countries are actively responding to them, and international academics are conducting research on them: KR. Richards (2004) analyzed forest carbon sinks for reducing carbon emissions in detail through more than 10 years of research [1]; HepburnC (2007) systematically reviewed and summarized the carbon emissions trading mechanism of the Kyoto Protocol [2]. D Tilman R (2009) analyzed the triple dilemma of global food, energy and environment, and considered carbon neutral as the most effective solution [3]; Lovell Heather C (2010) studied the inner mechanism of carbon offset mechanism in depth [4]; Sovacool Benjamin (2011) critically proposed the problems of global carbon trading market from four aspects [5]. In recent years, domestic scholars have also started to conduct in-depth research on this topic: Deng Mingjun (2013) applied the information visualization software CiteSpace II to generate a knowledge map of carbon neutral theoretical research, and deeply analyzed the knowledge base and frontier evolutionary trajectory of international carbon neutral theoretical research [6]; Wang Can (2020) believed that governments, enterprises, and individuals have crucial and focused roles in the process of moving toward a carbon neutral vision. A scientific policy system is needed to form a systematic and effective incentive mechanism to promote the rapid convergence of capital and talent toward carbon neutral technology innovation and market-oriented application [7]. Zou Cai (2021) believes that the "new energy" + "smart energy" system, which is clean, carbon-free, intelligent and efficient, is the development trend and direction of the world energy transition [8]; Yang Xiejun (2021) believes that in order to achieve the goal of carbon neutrality by 2060, it is necessary to establish some basic principles. In order to achieve the goal of carbon neutrality by 2060, Yang Xiejun (2021) argues that there is a need to establish some basic technological paths to promote low-carbon technology innovation and application, a market-oriented path to establish and improve the carbon market, and an administrative path to strengthen government guidance and regulation [9]; Wang Zhen (2021) focuses on the strategic choices of oil and gas enterprises under the vision of carbon neutrality from five aspects based on the analysis of their strategic transformation background [10]. Carbon neutrality means that enterprises, groups or individuals measure the total amount of greenhouse gas emissions produced directly or indirectly in a certain period of time, and offset the carbon dioxide emissions produced by themselves in the form of afforestation, energy conservation and emission reduction to achieve zero carbon dioxide emissions, and carbon neutrality is the main means for human beings to achieve the reduction of carbon dioxide emissions. As a pioneer in energy conservation and environmental protection, new energy vehicles also play an important role in reducing CO2 emissions, and their related technologies are beginning to develop in a more low-carbon and environmentally friendly direction in order to achieve the goal of carbon neutrality as early as possible. 2. Carbon Neutral Targets Promote New Energy Vehicle Technology Development Carbon emissions from transportation account for 26% of total global carbon emissions (Figure 1), and is the 2nd largest source of carbon emissions, including marine, land and air transportation[11] . The energy consumption of the transportation industry is large, and according to relevant data, about 60% of the world's oil consumption in 2020 in the field of transportation, of which the number of cars, as the main land transport, accounts for the largest proportion of land transportation and even transportation as a whole, and the current global car ownership exceeds 1 billion, of which more than 95% of cars are fuel cars, using gasoline and diesel as fuel, and the amount of oil consumed This accounts for about 1/3 of the total global oil consumption[12] . Carbon dioxide is the main component of fuel vehicle exhaust, and a large amount of carbon dioxide is emitted with vehicle exhaust every year worldwide, which has become one of the main sources of carbon emissions. As an important commodity for improving the quality of life, the willingness to purchase related products continues to rise, and car sales continue to grow, among which China has been the world's largest car sales market for many years, and the share of car sales in global car sales in 2020 and 2021 is more than 30%[13-14] . With the increasing car ownership, fuel vehicle exhaust emissions are expected to continue to increase, and the air pollution problem is becoming increasingly serious. At this time, there is an urgent need for new energy sources to replace gas and diesel, to achieve zero emissions of automobile exhaust, and to truly achieve zero pollution to the air environment, so new energy vehicles were born. New energy vehicles are not only the future of the automobile industry, but also an important way to achieve carbon neutrality. At present, most new energy vehicles use electricity as the power source, and a few use clean energy such as hydrogen fuel and solar energy [15]. The proportion of new energy vehicle sales to total vehicle sales is increasing year by year, and in the foreseeable future, it will completely replace fuel vehicles and completely achieve carbon neutrality in the automotive industry[16] . In recent years, new energy vehicle technology has started to develop in a more low-carbon and energy-efficient direction, both in terms of the core three electric (power battery, electric control system, and drive motor) technology and related auxiliary technology innovation to achieve the main goal of reducing carbon dioxide emissions. 2.1 Power battery 2.1.1 Energy density Battery technology is the core technology of new energy vehicles, and its development trend often determines the overall development direction of the industry. Ningde Time, LG, Panasonic, BYD, AVIC Lithium and other power battery companies are actively developing high energy density batteries and solid state batteries. The U.S. luxury electric car Lucid Air, which was delivered in October 2021, has an EPA (U.S. Environmental ProtectionAgency) range of 832 km, making it the world's first mass-produced electric car with a range of more than 800 km. In November 2021, the Ministry of Industry and Information Technology of China announced the Recommended Model List for the Promotion of New Energy Vehicles (batch 10, 2021), the AION LX Plus pure electric SUV from Guangzhou has an energy density of 205 W-h/kg and a NEDC range of 1,008 km, and will be officially launched in January 2022, becoming the world's first pure electric vehicle with an energy density of over 200 W-h/kg and a range of over 1,000 km. In addition, Utilai, BYD, SAIC and other vehicle manufacturers are planning to launch new energy models with semi-solid-state batteries in the future. The development trend of power battery energy density is shown in Figure 2. 2.1.2 Safety Although the spontaneous combustion rate of new energy vehicles is lower than that of fuel vehicles, once the power battery catches fire, it is very easy to produce an explosion, causing much higher personal and property losses than fuel vehicles. March 2020 BYD took the lead in releasing the main new energy vehicle safety blade battery, which can easily complete the pinprick test, first equipped with its Han model, BYD Han sales have been climbing since its launch, and so far there has not been a battery fire accident. In March 2021, BAE released the magazine battery system safety technology, and successfully passed the pinprick heat dispersion test to realize the battery pack pinprick without fire, and no major safety accident has occurred in its models so far. In September 2021, Great Wall Motor released Dayu battery, which can achieve full coverage of the battery cell chemistry system and ensure that the battery pack does not catch fire or explode in the event of thermal runaway triggered by a single or multiple cells at any location, and is the first to be installed in its salon car products. Future power battery safety will be significantly improved to enhance a safer driving environment for users. 2.1.3 Charging and switching technology In addition to power battery technology, as an important safeguard technology for new energy vehicles, charging and swapping technology has been continuously developed and has been greatly improved, including Porsche's super charging technology with a maximum power of 350 kW launched in September 2018, which can achieve ordinary household pure electric cars charging to 80% power within 15 min, and the super charging piles of Tesla, Azera and Xiaopeng can reach charging power of 180-250 kW and achieve charging to 80% power within 30 min [18], but even the fastest Porsche Superchargers are still not as fast as fuel car refueling, and the actual charging time may be longer due to the significant slowdown in the final stage caused by trickle charging, and the gap between the charging efficiency of pure electric vehicles and fuel car refueling is still obvious. In recent years, battery swapping technology has emerged as a new way of replenishing energy in new energy vehicles. The battery swapping stations of Azera and BAIC New Energy can replace the batteries of pure electric vehicles within 5 min, which is almost equal to the refueling time of fuel cars and is the most effective way to solve mileage anxiety[19] . 2.2 Electrical control system 2.2.1 Silicon carbide (SiC) power module Electronic control system is the control center of new energy vehicles, its importance is self-evident, electronic control technology in the early development of new energy vehicle industry is slow, in recent years, rapid development, especially the application of new materials in this field is particularly prominent, the past new energy vehicles generally use IGBT power module, in recent years the emerging silicon carbide began to be used in pure electric models, Tesla, Infineon, BYD, Mitsubishi, Hitachi Tesla, Infineon, BYD, Mitsubishi, Hitachi, CTS Times and other major global IGBT manufacturers are actively developing silicon carbide power modules for new energy vehicles. 2018 Tesla Model 3 pure electric sedan began to change silicon carbide power modules one after another, becoming the world's first new energy model equipped with silicon carbide power modules, in addition, BYD, Azera and other vehicle manufacturers have begun to use silicon carbide power modules, significantly improving the overall efficiency and service life of the electronic control system In addition, BYD, Azera and other vehicle manufacturers have started to use silicon carbide power modules, which significantly improve the overall efficiency and service life of the electronic control system and further reduce energy consumption. 2.2.2 DMI super hybrid technology Hybrid cars as pure electric vehicles to replace fuel cars in the transition model, the same in recent years, a major breakthrough in electronic control technology, although the hybrid car can effectively solve the long-distance travel mileage anxiety, but the feeder situation even higher than the fuel car class energy consumption has become a major criticism, coupled with the generally higher than the price of the same class of fuel cars, making it an awkward situation, sales have long been stagnant. In January 2021, BYD released DMI (Dual Mode Intelligent) super hybrid technology, which unprecedentedly eliminates the transmission in the fuel powertrain and replaces it with a single-speed planetary gear, using a self-developed Snapdragon engine with a thermal efficiency of 43%. The DMI system mainly relies on high-powered high-efficiency motors for driving, and the main task of the engine is to generate electricity in the high-efficiency speed range and directly drive the vehicle at the right time, making it easy to achieve ultra-low fuel consumption in the case of power feed, and the fuel consumption of BYD DMI models in the state of power feed for 100 km is generally as low as about 4 L, completely overturning the previous high fuel consumption, this remarkable effect not only relies on high-efficiency engines, but also the electronic control system plays an important role in it. The electric control system also plays an important role. Once this revolutionary technology was released, it immediately sent shockwaves through the industry, and the DMI model became a hot seller in the market as orders were backlogged and demand outstripped supply, boosting the overall sales of hybrid vehicles. In addition, the hybrid vehicle market started to boom again due to the revolutionary technology breakthrough. 2.3 Drive motor 2.3.1 Motor performance The drive motor directly drives the vehicle and is the core component of the new energy vehicle. The drive motor can release the maximum torque at the starting stage, which makes the acceleration performance of the new energy vehicle far better than that of the fuel car of the same grade, but the torque of the drive motor decays rapidly in the back-end high-speed stage, and the single gear ratio also makes its top speed generally inferior to that of the fuel car of the same grade. In recent years, drive motor technology in power, layout, system innovation: early single drive motor output power is generally less than 80 kW, with the production process and technology level of maturity, the drive motor output power gradually increased, to 2018, generally in the 120kW or so, the Porsche Taycan pure electric coupe in 2019 listed rear motor power up to 350 kW, refreshing the highest power record of the drive motor. Due to the small size of the drive motor, no transmission, you can arrange multiple drive motors in the body, most of the new energy models currently on sale generally use single/dual motor configuration differentiated sales, to enrich the product line at different price levels, some models even arranged three drive motors to further enhance performance; permanent magnet synchronous motor and AC asynchronous motor have their own advantages and disadvantages, in recent years, the vehicle manufacturers began to use these two drive Tesla, Azera and other companies have launched models with a mix of permanent magnet synchronous motors and AC asynchronous motors, with significantly higher overall performance than previous models. 2.3.2 Flat wire motor The stator winding includes the iron core, copper wire winding, and insulation material. The difference between a flat wire motor and a round wire motor is the way the copper wire is formed, the flat wire facilitates the increase of the slot fill rate of the motor, generally the slot fill rate of a round wire motor is about 40%, while the slot fill rate of a flat wire motor can reach more than 60%. Compared with round wire motors, flat wire motors have better thermal conductivity and lower temperature rise, with some data showing that the temperature rise of flat wire motors is about 10% lower than that of round wire motors. Overall, compared to round wire motors, flat wire motors are more efficient, smaller, lighter and lower cost, which is the inevitable development trend of future drive motors. In recent years, automotive companies have started to gradually use flat-wire motors to replace round-wire motors, as early as 2007 Chevrolet Volt began to use Hair-Pin (hairpin flat-wire motor), in 2013 Nissan used flat-wire motors in its electric vehicle products, in 2015 Toyota's fourth generation Prius began to install flat-wire motors, with the rising sales of Prius, flat-wire motors began to be used on a large scale, followed by SAIC, Great Wall, Porsche, Dongfeng, Dongfeng and other electric vehicles. In the future, flat-wire motors will further replace round-wire motors and become the mainstream of new energy vehicle drive motors. 2.3.3 Integrated motor assembly The traditional drive motor is independent of the power battery and electronic control system, the power battery will transmit electrical energy to the motor to drive the vehicle, and controlled by the electronic control system, each part of the division of labor to ensure the overall stable operation of the vehicle, but the disadvantages of the separate independent structure is also very obvious, especially the separation of the drive motor and electronic control system will occupy more space in the vehicle, the power battery can only reduce the relative arrangement, while increasing the Mass, can not further increase the battery capacity combined with greater vehicle quality will weaken its acceleration and range, this disadvantage has become more and more obvious in recent years. In response to this problem, companies have begun to develop multi-integrated motor assemblies that integrate drive motors and electronic control systems to save space and reduce vehicle mass, and most importantly, to make integrated motor assemblies further improve transmission and control efficiency and enhance overall vehicle performance.In recent years, companies such as Jingjin Electric (JJE), Founder Motor (FDM) and Huawei have already launched related products, and BYD has launched the world's first eight-in-one motor assembly on the e3.0 platform, integrating drive motor, gearbox, drive motor controller, high-voltage power distribution unit, high-voltage DC converter (Di⁃rect Current-Direct Current converter), on-board bi-directional charger, and complete vehicle performance. The integrated drive motor, gearbox, drive motor controller, high-voltage distribution unit, high-voltage and low-voltage DC converter (Direct Current-Direct Current converter), on-board bi-directional charger, vehicle control unit, and battery management system will increase the overall efficiency from 86% to 89%, reducing the 100 km electric power consumption by 10% compared to the same class of vehicles, achieving faster acceleration and longer driving range. With the gradual maturity of the integrated motor technology, the number of models with this structure will increase. 2.4 Auxiliary technology In addition to the core technologies, the auxiliary technologies of new energy vehicles have also made rapid progress. Due to the persistent mileage anxiety problem and the gradual withdrawal of new energy vehicle subsidies, improving the range of new energy vehicle enterprises has become an urgent task. The NVH problem, which has never been effectively solved by fuel vehicles, has been solved in the field of new energy vehicles, and the innate quietness and smoothness of drive motors have significantly reduced noise and vibration. The phenomenon of smart network technology, with the inherent structural advantages of new energy vehicles, has become a standard feature of new energy vehicles[21] . The rapid changes in auxiliary technologies have not only enhanced the core strength of new energy vehicle products, but also greatly improved comfort and functionality, further increasing the overall competitiveness of new energy vehicles. 3. Conclusion The development of new energy vehicle technology determines the overall development direction of its industry. The carbon neutral target has brought the development of new energy vehicle technology to a new stage, showing the following 3 trends. 3.1 The trend of low carbon and energy saving is obvious The initial development of new energy vehicle technology mainly focused on increasing motor power and driving range, but due to the slow improvement of battery energy density, high manufacturing costs, and the outstanding acceleration ability that cannot be fully played out in urban travel scenarios, the advantages of new energy vehicles in terms of comprehensive performance are not obvious, and the price is significantly higher than the same level of fuel vehicles, making it in an awkward situation, and early sales are slow to increase. In recent years, relevant enterprises have further improved energy density and motor power while developing more advanced electronic control systems and integrated motors to reduce energy consumption and achieve increased range, and the application of environmentally friendly and efficient new materials such as silicon carbide and flat copper wire has significantly reduced carbon emissions during the production of core components for new energy vehicles. Both aspects are developing in the direction of low carbon and energy saving. 3.2 The trend of intelligence is obvious New energy vehicles are very suitable for intelligence and automation due to their simple structure and more electronic devices. In recent years, intelligent technologies such as artificial intelligence, automatic driving and remote network connection have started to be widely applied in the field of new energy vehicles, and the intelligence level of new energy vehicles is rapidly improving. New energy vehicles are no longer simple transportation vehicles, but mobile spaces that can communicate with drivers and provide them with comfortable and convenient services. 3.3 The trend of industry standardization is obvious The early development of the new energy vehicle industry was not only at a general level, but also at an uneven level of internal development, with huge gaps, and the enterprises each setting their own technical standards suitable for their own development stages, resulting in different technical parameters, especially in the charging and switching process, and even the inability to charge due to the lack of uniform interfaces. In recent years, the relevant departments began to develop unified standards, and relevant enterprises began to respond positively to produce products with unified interfaces and technical parameters, and have now achieved unified charging standards. With the goal of carbon neutrality becoming an important development direction for global environmental protection, new energy vehicle technology will develop in a more low-carbon and energy-saving direction, and more related new technologies will emerge in the future. Reference: [1] RICHARDS K R, STOKES C. A Review of Forest Carbon Sequestration Cost Studies: A Dozen Years of Research[J]. Climatic Change, 2004, 63(1-2):1-48. [2] HEPBURN C. Carbon trading: A Review of the Kyoto Mech⁃anisms[J]. Annual Review of Environment and Resources,2007(32):375-393. [3] TILMAN D, SOCOLOW R, FOLEY J, et al. Beneficial biofu⁃els-the food, energy, and environment trilemma[J].Sci⁃ence,2009(325):270-271. [4] LOVELL H C. Governing the carbon offset market[J].Wiley Interdisciplinary reviews-Climate Change, 2010(3):353-362. [5] SOVACOOL B K. Four problems with global carbon mar⁃kets: A critical review[J].Energy & Environment,2011 (6):681-694. [6] Deng MJ, Luo WB, Yin LJ. 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Chapter 3 Reducers and Multi-Shift Boxes 3.1 Needs and advantages of multi-gear The development direction of electric drive, one is higher power, torque density, higher limit output speed, higher system efficiency, lower system cost, higher NVH performance, such a background has given birth to a very diverse segmentation of technical routes, such as high speed, oil cooling, high voltage, disconnecting device, dual motor, SIC, excitation, and so on. Multiple gears increase the torque while increasing the speed of the vehicle. The increased torque makes the motor a little smaller, which reduces losses while achieving higher efficiency. By having two gears, not only can the maximum torque be increased in the lower gears but also the maximum speed can be increased, optimizing the motor for the best efficiency range while increasing the range. Multi-gear is a good technical solution, for example, two-speed gearboxes in the low-speed gears to make the speed ratio larger, acceleration time, climbing performance will be better, high-speed gears can be made more efficient, so in some performance cars to do some multi-gear solutions. But as the motor speed gets higher and higher, the speed ratio can be made larger, and with the application of silicon carbide technology, the whole differentiation of multiple gears is not as obvious as we think, so some companies' choice is to use high speed motors or silicon carbide technology to do these performance cars, so that the same effect can be achieved. From the control point of view, the motor response is fast, multi-gear in the gear switching process there is time loss, after adding a gear and to solve these problems in the process of shifting, how to balance this time, or how to make it faster, this is a factor to consider. With the development of motor performance, now the motor efficiency bandwidth has been made very wide, if we attack the German market, multi-gear is indeed a demand, because he needs to achieve a maximum speed of 250 km or even higher, so that single-gear is difficult to cover the acceleration performance of the lower gears and high-speed fuel consumption, but in China's working conditions under the current motor development, single-gear can already meet the basic needs of Chinese customers. But in the current development of the motor under the conditions of China, single gear can already meet the basic needs of Chinese customers. Six dimensions summarize the advantages of multi-gear. First: reduce the performance requirements of the motor, a large transmission ratio of the first gear can reduce the maximum torque and peak power of the motor, a small transmission ratio of the second gear can reduce the maximum speed of the motor, reducing the performance requirements of the drive motor. Second: improve the overall vehicle dynamics, using the same motor, first gear large ratio can improve the acceleration, climbing performance, second gear small ratio can improve the maximum speed, improve the overall vehicle dynamics performance. Third: improve the economy of the vehicle, through the optimization of the two speed ratios and the shift rule, can improve the efficiency of the motor operation, improve the economy of the vehicle to increase the range. Fourth: improve NVH and reliability, the second gear small ratio reduces the maximum speed of the motor, reduces the high frequency whistle and high speed vibration of the drive system, improves the quality of the vehicle, improves NVH performance, and also improves the risk of failure of high-speed rotating parts. Fifth: Matching oil-cooled flat wire motor. Reduces the peak motor speed requirement, circumvents the high-speed skin effect of flat-wire motors, gives full play to the technical advantages of oil-cooled flat-wire motors, and greatly improves the electric drive system and power density. Sixth: Reduce system cost. If the same power and economy requirements are maintained, the system cost can be reduced by reducing the motor performance requirements and battery capacity. 3.2 Multi-shift system with clutch and synchronizer BorgWarner's current two-gear system is divided into two parts in terms of structure. The first-gear system is operated by a multi-mode clutch for gear shifting, and the second-gear system is operated by a wet clutch, while a synchronizer is added to enhance efficiency and realize intelligent disconnection and intelligent parking, and an electronic limited-slip differential can be optionally installed to improve the efficiency of the whole vehicle and the stability of the whole vehicle. Specifically, the multi-mode clutch can play the purpose of dog teeth + one-way clutch, multi-mode clutch to achieve disconnect mode, will achieve two-way torque through the implementation of the structure, to switch to a one-way clutch mode will fall into the slot, so that it becomes a one-way mode. In addition, integrated disconnect and parking function, through the different clutch mode switching, to disconnect the two gears at the same time this is called intelligent disconnect, which can further improve the efficiency of the whole vehicle. To achieve disconnection is to simultaneously disconnect and first and second gear this is intelligent disconnection, this process does not require additional execution structure. Smart park and smart disconnect are reversed first and second gear combined at the same time, so that the smart park function is achieved, all clutches remain in the locked state, this is the smart park mode. The process from first to second gear, the design concept is the design concept of power shifting, the clutch of two gears in first gear, energy recovery can be reversed, in first gear when the multi-mode clutch lock synchronizer disconnected, normally closed clutch disconnected, to open the normally closed clutch, reduce the synchronizer need to shift, the normally closed open when the synchronizer will shift, the synchronizer to shift after the normal Closed clutch returns to the process of shifting to first gear to second gear, and finally to further enhance efficiency, the multi-mode clutch is then switched from single-phase mode to bi-directional to further reduce the loss of multi-mode. Synchronizer is used with normally closed clutch, there is a scheme of multi-mode clutch with normally open clutch, this time the synchronizer is eliminated. The first is for efficiency considerations, if there is no synchronizer, there is still some internal loss, we will disconnect the synchronizer when the clutch is still closed state, this time is not loss. Add synchronizer to achieve two main functions, one is intelligent disconnection, and another is intelligent parking, without the introduction of additional parking system to achieve the two functions. 3.3 Torque vectoring and disconnection system BorgWarner's torque vectoring management system has two motives for development: first, to replace the traditional differential with a dual clutch system in electric drive to achieve the role of torque vectoring; second, to integrate the disconnect function, now the application target is electric and hybrid P4 architecture, now this product is still placed on the rear auxiliary drive, so this is why we need the disconnect function for this product. Torque vectoring helps to improve the dynamic stability of the vehicle, integrated disconnect function can improve the efficiency of the vehicle, reduce the vehicle's electricity consumption. The clutch system inside the electric drive system can also play a role in limiting the torque of the entire transmitter to avoid torque shock. This system controls the torque distribution between the left rear wheel and the right rear wheel by means of a double clutch, while the traditional rear wheel, the traditional left wheel and the right wheel are realized through a differential, this one is through a clutch, each clutch controls the left and right wheels separately. A series of optimization, the entire disconnect mode dragging torque down to 2NM or less. The maximum torque capacity is 2600NM single side expandable, we are the sixth generation of the actuator and integrated controller, with AUTOSAR, CAN, CANFO and other safety features. About the electric bridge disconnect system, now for the electric 4WD auxiliary drive of this efficiency improvement, auxiliary drive non-working state for the whole vehicle torque or power loss reduction there are two programs, one is to use induction motor, and then is the use of this synchronous motor + dynamic system, the program is synchronous motor + dynamic system. Through the simulation of the system, including communication with various customers, we now conservatively estimate that the system can save the energy consumption of the whole vehicle by about 1%-5%, and we are now conducting road tests with some customers, and the results we get now are much better than 5%. 3.4 Multi-gear gearbox without clutch and synchronizer No matter what the motor does, no matter 20,000 rpm or 30,000 rpm, the two-speed gearbox can always widen the torque speed range, which in turn can further improve the driving speed, climbing degree and driving time of the whole vehicle, which are the evaluation indexes of power, and also can change the working point of the motor through gear shifting to make it more efficient. The speed ratio of the first gear can be made larger, and the maximum torque of the motor can be lowered, thus reducing the total volume and cost of the whole powertrain, and because there is a neutral gear after two gears, it is more convenient for the maintenance of the whole car. When there is only one gear, the working area is more inclined to the low-efficiency area. If there are two gears, the working point can be moved to the high-efficiency area with equal power, thus improving efficiency. The range improvement is more than 10% for commercial vehicles and 7% for passenger cars when compared with no gear change. Commercial vehicles should return to the more mass-produced, more mature parallel shaft mechanical transmission, very high efficiency. Further is the parallel shaft mechanical transmission without clutch, in electric vehicles, with clutch, motor speed and clutch control are challenges, if the clutch is removed, the clutch of the three roles of the motor can also be completed, the clutch is removed, the cost can be reduced, the structure is more compact, reliability is also greatly improved. Central drive is a very common configuration in commercial vehicles, that is, the drive motor and mechanical transmission, arranged together to drive our rear axle through the drive shaft. The advantage is that the separation and engagement of the clutch is eliminated, and the motor can be actively synchronized to achieve the control of gear shifting. But there is a problem, the inertia of the motor rotor rotation is really large, and the rotational inertia of the transmission input will increase significantly, which will lead to a longer power interruption, because the synchronization capacity will increase and the synchronizer wear will be more serious, and this time the active synchronization control of the motor has to be used. In a conventional fuel car AMT inside there is a clutch, when shifting you only need to control the shift force inside the transmission. If there is a synchronizer inside the system, just take the clutch out, this is possible to do active synchronization control, control its relative speed.