Permanent Magnet Motors and Induction Motors

Update:31 Jul 2020

At present, motors can be classified according to the working power source, structure and working principle, different starting and operating modes, and different uses. Among them, the motors suitable for driving new energy vehicles mainly include Permanent Magnet Motor Assembly, induction motors and switched reluctance motors.

An induction motor can also be called an AC asynchronous motor. It is a type of motor in which the rotating magnetic field formed after the stator winding and the magnetic field of the induced current in the rotor winding interact physically to generate an electromagnetic torque to drive the drive to rotate. The permanent magnet motor mainly refers to a permanent magnet synchronous motor. The so-called synchronization means that the rotation speed of the rotor is always consistent with the current frequency of the stator winding.

With regard to these two types of motors, the current market share of permanent magnet synchronous motors in China is higher.

First of all, at the same technological level, in addition to field weakening control, permanent magnet synchronous motors perform better than induction motors in terms of torque density, power density and efficiency, and their energy efficiency and cruising range are relatively high;

Secondly, the permanent magnet synchronous motor can still guarantee high efficiency in the transient state, and the motor is small in size and light in weight, suitable for frequent start and stop conditions and small passenger car layout space.

Third, the permanent magnet motor does not require an efficient and complex cooling system like induction motors, which is conducive to the design and manufacture of the entire vehicle.

Finally, permanent magnet materials such as neodymium iron boron required by permanent magnet synchronous motors are important rare earth resources, and China has 70% of the world's rare earth resources, and the total output of neodymium iron boron and other magnetic materials has reached 80% of the world. Due to the great advantage of domestic rare earth resources, it is most logical to choose a high-efficiency permanent magnet synchronous motor.

But in fact, induction motors and permanent magnet motors have no exact distinction between advantages and disadvantages. Judging from the current technical advantages, permanent magnet synchronous motors have a higher market share. This does not mean that induction motors are inferior to permanent magnet motors.

Compared with permanent magnet motors, induction motors have a wider speed range, lower cost, simpler process, and their operation is also reliable and durable. Although induction motors do not have the advantage in terms of weight and size, if the battery mileage increases significantly in the future and the induction motors are optimized for volume, its market share will increase greatly in the future.

Generally speaking, induction motors are more suitable for high-performance and high-speed working conditions, while permanent magnet synchronous motors are more suitable for frequent start-stop working conditions. Induction motors and Permanent Magnet Components have their own strengths and weaknesses. The type of motor used depends mainly on the positioning of the model and the technical field that the company is good at.