The drive motors of new energy vehicles are mainly divided into three categories: permanent magnet synchronous, AC asynchronous, and switched reluctance motors. Due to their different characteristics, they are used in different applications.
1. Rare earth permanent magnet synchronous motor
In principle, it is possible to achieve small size, light weight, high power density, high reliability, high speed regulation accuracy, and fast response speed. Due to the high power density of permanent magnet synchronous motors, their working efficiency can reach up to 97%, enabling them to output maximum power and acceleration for vehicles. Therefore, they are mainly used in new energy passenger vehicles with the highest requirements for energy-volume ratio.
The disadvantages are lower maximum power and higher cost. AC asynchronous motors are inexpensive and reliable; however, their inherent limitations include low power density, complex control, and limited speed range. Their price advantage makes them widely used in new energy buses.
2. Induction (Asynchronous) Motor
It can withstand significant temperature variations during operation. Conversely, significant temperature variations can damage permanent magnet motors. Induction motors, on the other hand, can adjust their output torque over a wide range, do not require a heat dissipation mechanism, are lightweight (about the size of a watermelon, weighing only 52 kg), and can operate at speeds from 0 to 12,000 rpm, thus eliminating the need for additional transmission mechanisms. Therefore, its weight is a significant advantage among new energy vehicles.
The disadvantages are that the rotor rotation speed is difficult to control, energy consumption is high, power factor is lagging, structure is complex, and the control system of the induction (asynchronous) motor is complex, with high technical requirements and high manufacturing cost.
3. Switched reluctance motor
It is inexpensive, has a simple and reliable circuit, and a wide speed range; however, it generates significant vibration and noise, has a complex control system, and produces a large pulse current to the DC power supply. It is used in large buses and BYD electric vehicles.
Among them, Japanese and Korean cars mostly use permanent magnet motors, which have relatively high speed range and efficiency, but require the use of expensive system permanent magnet materials such as neodymium iron boron; European and American cars mostly use AC induction motors, mainly due to the scarcity of rare earth resources and the consideration of reducing motor costs. Their disadvantages are mainly a small speed range and low efficiency, requiring a higher-performance speed controller to match the performance.
