Our electric vehicle conversion mainly uses four types of electric vehicle motors, brushless DC permanent magnet motors, AC permanent magnet synchronous motors, AC asynchronous induction motors and switched reluctance motors. These four motors have their own characteristics, and we choose the appropriate motor according to the specific uses of electric vehicles.
Brushless DC permanent magnet motor
Many electric vehicles with speeds below 80 kilometers per hour, such as sightseeing cars in scenic spots, golf carts, mobility vehicles for the elderly, etc., which use DC motor solutions because DC motor products are mature, easy to control, have excellent speed regulation, and are cheap. Features include simple maintenance. The rotor of this type of motor is a permanent magnet, which reduces the loss caused by excitation. The stator is equipped with windings to generate torque through rectangular pulse current. Due to the low speed of this type of electric vehicle, cooling and heat dissipation are relatively easy. Under normal circumstances, high temperatures will not cause the permanent magnets to demagnetize.
AC asynchronous induction motor
Due to its advantages of high efficiency, large power, and suitable for high-speed operation, AC asynchronous induction motors are currently the most widely used motors in high-power electric vehicles, such as Tesla Model S and Model X vehicles. The area where asynchronous electric induction machines are mostly used is the United States, because in the United States, highways have already reached a certain scale. Except for big cities, cars generally drive continuously at a certain high speed, so they can operate at high speeds and have a relatively high speed at high speeds. High-efficiency asynchronous motors are widely used. Usually this type of motor adopts the relatively high-cost vector control method, so its controllability is very perfect and it has a wider speed rang
AC synchronous permanent magnet motor
The control system of a permanent magnet motor is simpler and less expensive than the control system of an AC asynchronous motor, but the manufacture of permanent magnet motors requires rare earth resources. In the past, due to limitations of the permanent magnet material itself, the permanent magnets of the rotor would demagnetize under conditions of high temperature, vibration, and overcurrent. Therefore, Tesla did not use AC synchronous permanent magnet motors when it first developed electric vehicles. In recent years, China has invested a lot of research and development expenses in targeted research and development, which has effectively improved the phenomenon of permanent magnet motors prone to demagnetization under complex working conditions, which affects the output torque of the motor. Improved AC synchronous permanent magnet motors and their control System cost response is all offered, but performance is very solid. Currently, Tesla Model 3 and Model Y manufactured in China also use AC synchronous permanent magnet motors. Therefore, China, which is rich in rare earth resources, prefers electric vehicle drive solutions using permanent magnet motors.
Switched reluctance motor
As a new type of motor, the switched reluctance motor does not use light rare earth permanent magnet materials. Compared with other types of drive motors, the switched reluctance motor has the simplest structure. The stator and rotor are both laminated with ordinary silicon steel sheets. The double salient pole structure has no windings on the rotor and the stator is equipped with simple concentrated windings. It has many advantages such as simple and solid structure, high reliability, light weight, low cost, high efficiency, low temperature rise, easy maintenance and so on. Moreover, it has the excellent characteristics of good controllability of DC speed regulation system, is suitable for harsh environments, and is suitable for use as a drive motor for electric vehicles. However, switched reluctance motors have disadvantages such as large torque fluctuations, the need for a position detector, nonlinear system characteristics, jump rotation of the magnetic field, and complex control systems; they can generate large pulse currents for DC power supplies. In addition, the switched reluctance motor has a double salient pole structure, which inevitably causes torque fluctuations. Noise is the main shortcoming of the switched reluctance motor. Electric vehicles in Japan and Europe have plans to use switched reluctance motors.