Electric vehicle motor classification
The motors used in electric vehicles now mainly include DC motors, AC induction motors, permanent magnet motors and switched reluctance motors.
1. Electric vehicle DC motor
Advantages: The starting acceleration is huge, the electromagnetic torque control characteristics are good, the speed adjustment is convenient, the control device is simple, and the cost is low.
Disadvantages: There is a mechanical commutator. When running under high speed and large load, there is spark on the surface of the commutator, so it is not suitable for the motor speed. Compared with other drive systems, it is at a disadvantage and has gradually been eliminated.
2. Electric vehicle AC induction motor
The stator of the AC induction motor is used to generate a magnetic field, and is composed of a stator core, a stator winding, an outer casing of the iron core, and a bearing supporting the rotor shaft. AC motors have the advantages of low price, maintenance, and small size, but the control of AC motors is more complicated. It has become the first choice for AC-driven electric vehicles.
3. Electric vehicle AC induction motor
The permanent magnet motor uses a permanent magnet to generate the air gap magnetic flux, and the permanent magnet replaces the field coil in the DC motor and the field magnet of the stator in the induction motor. Permanent magnet synchronous motor has high efficiency, high moment inertia ratio and high energy density. Especially its low speed and high torque can meet the needs of vehicles traveling on complex and varied roads. It is a high performance and low carbon environment-friendly motor with rare earth permanent magnets. The emergence of materials is expected to compete with AC induction motors for the market. Especially in the small and medium power range, it has been widely used.
4, electric vehicle switch reluctance motor
The switched reluctance motor stator and rotor are double salient pole structures in which ordinary silicon steel sheets are laminated.
Advantages: simple and reliable, wide adjustable speed range, high efficiency, flexible control and low cost.
Disadvantages: large torque fluctuations, high noise, position detectors, nonlinear characteristics, etc. The application is limited.
The power performance of an electric car has a direct relationship with the power of the electric car. The higher the power, the better the acceleration performance and the maximum climbing ability of the electric car, the better the quality, and the volume of the motor will increase. However, the motor can not work under high efficiency for a long time, which will reduce the utilization rate of the electric vehicle and reduce the mileage of the car.
In general, the rated power of the selected motor should meet the maximum speed of our car. The peak power of the motor must meet the requirements of the maximum grade and acceleration performance of the car. Calculate the power required by our motor according to the following formula.
The driving force of the vehicle is all from the on-board motor. The driving force required by the car is different under different working conditions. The motor can only output the torque. The required force of the vehicle under various working conditions is caused by the output torque of the motor passing through the drive train. The drive wheel pushes the vehicle forward in the form of torque. The torque required to drive the motor can be calculated from the driving force required by the vehicle.
The choice of motor speed is directly related to the speed of the car. Its maximum speed should meet the maximum speed requirements of the car.
