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.