Comparison of common drive motors for electric vehicles
1) DC motor
1 DC motor outline drawing and internal structure
2 Advantages: The motor technology is relatively mature, with the characteristics of easy control and excellent speed regulation.
3 disadvantages: mechanical structure. Such as brushes and mechanical commutators; short-term overload capacity; motor speed is limited; in the long-term work, the mechanical structure of the motor will cause losses, improve maintenance costs; The rotor generates heat, wastes energy, and is difficult to dissipate heat. It also causes high-frequency electromagnetic interference.
4 Basic trends: DC motors have the widest range of applications in the field of variable speed motors. Most of the early electric vehicles used DC motors as drive motors. However, its shortcomings are more obvious and can not be overcome in the long run. The current electric vehicles have basically eliminated DC motors.
2) AC asynchronous motor
1 AC motor outline drawing and internal structure
2 Advantages: The stator and rotor are laminated by silicon steel sheets, and the two ends are packaged with aluminum caps. There are no mechanical parts that are in contact with each other between the stator and the rotor. The structure is simple, the operation is reliable and durable, and the maintenance is convenient. AC asynchronous motors have the advantages of high efficiency, large specific power, and high speed operation.
3 Disadvantages: In the case of high-speed operation, the rotor of the motor is seriously heated, and the motor must be cooled during operation. At the same time, the drive and control system of the asynchronous motor is complicated, and the cost of the motor body is also high. Compared with permanent magnet motors and switched reluctance motors, the efficiency and power density of asynchronous motors are low, which is unfavorable for improving the maximum mileage of electric vehicles.
4 Basic trend: AC asynchronous motor is a kind of motor widely used in industry, and has been mass-produced. At present, many electric vehicle manufacturers choose AC asynchronous motor as the starting motor, and the basic control adopts the vector control method. In the application of large electric buses, AC asynchronous motors have strong vitality.
3) Permanent magnet motor
1 permanent magnet motor outline drawing and internal structure
2 Classification: Permanent magnet motors can be divided into two types according to the current waveform of the stator windings. One is a brushless DC motor with a rectangular pulse wave current; the other is a permanent magnet synchronous motor with a sine wave. Current.
3 Advantages: Cooling is relatively easy, no commutation sparks are generated during operation, safe and reliable operation, convenient maintenance and high energy utilization.
4 Disadvantages: The permanent magnet motor has a small power range, and the general maximum power is only tens of kilowatts. Permanent magnet materials can cause magnetic decay and are prone to damage. Moreover, the price of permanent magnet materials is relatively high, so the entire motor and its control system are costly.
5 basic trends: At present, permanent magnet motors are already mainstream motors in electric vehicles.
4) Switched reluctance motor
1Switched reluctance motor outline drawing and internal structure
2 Advantages: The structure of the switched reluctance motor is the simplest. The stator and rotor are double salient pole structures formed by laminating ordinary silicon steel sheets. There is no winding on the rotor. The stator is equipped with simple concentrated windings. It has simple and sturdy structure and reliability. High quality, light weight, low cost, high efficiency, low temperature rise, easy maintenance and many other advantages.
3 Disadvantages: Switched reluctance motor as a new type of motor, the current product performance needs to be improved and improved.
4 Basic trend: Compared with other types of drive motors, it has the excellent controllability of the DC speed control system and is suitable for harsh environments. It is very suitable for use as a drive motor for electric vehicles.
5 Basic conclusions: As electric motor drive motors, DC motors and permanent magnet motors are too poorly adaptable in structure and complex working environment, and mechanical and demagnetization failures are prone to occur. The application of switched reluctance motors to electric vehicles is an inevitable trend.
