Rare earth permanent magnet motor is one of the three important components of new energy vehicles, which are different from traditional vehicles. It is also the power source of new energy vehicles. There are two kinds of permanent magnet synchronous motor and AC asynchronous motor. Motor is a kind of electromagnetic device which realizes the conversion or transmission of electric energy according to the law of electromagnetic induction. Its main function is to produce driving torque.
1. The working principle of induction motor (induction motor) is to generate induced current in the rotor through the rotating magnetic field of the stator and generate electromagnetic torque. The magnetic field is not directly generated in the rotor. Therefore, the rotor speed must be less than the synchronous speed (without this difference, that is, the slip rate, there is no rotor induced current), therefore called asynchronous motor. And intelligent industrial motor rotor itself produces a fixed direction of the magnetic field (with a permanent magnet or DC current), the stator rotating magnetic field "drag" the rotor magnetic field (rotor) to rotate, so the rotor speed must be equal to the synchronous speed, also called synchronous motor.
2. The power density of intelligent industrial motor is about 25% higher than that of asynchronous motor of the same capacity. For motors with the same power, intelligent industrial motors are 2 frame sizes smaller than asynchronous motors. Small size means less iron loss and less mechanical loss.
3. When the asynchronous motor is working, the rotor winding will absorb part of the electric energy excitation from the battery and consume the electric energy. This part of the electric energy is finally consumed by the current heating in the rotor winding. When permanent magnet synchronous motor is embedded in the rotor, the rotor magnetic field is established by the permanent magnet without electric energy excitation. In the normal operation of the rotor and stator magnetic field synchronous operation, there is no induction current in the rotor, there is no rotor resistance loss, start up can improve the motor efficiency of about 40%.
4. When the asynchronous motor starts, the current is 6-7 times of the rated current, which is not good for the life of the motor. In order to achieve the required torque, there is even an increase in the motor type, while the motor is running at a low load, and the efficiency is reduced. No current shock, prolong the service life, the motor in a reasonable load work. Permanent magnet synchronous motor speed control precision. In the high speed requirements of the occasion has greater advantages.
At present, only a few enterprises such as Tesla use AC induction motor in the market, while the vast majority of enterprises represented by BMW and BYD all use rare earth permanent magnet motor as the drive system. Compared with the two kinds of motors, rare earth permanent magnet motors have obvious advantages, which is the trend of industry development.
