What's the difference between permanent magnet synchronous motor and asynchronous motor?

At present, there are mainly two kinds of motors in the new energy market, permanent magnet synchronous motor and asynchronous motor, both of which have their own specialties. Many car companies choose different motors according to different costs, usage scenarios and technical requirements.

For example, Tesla Model 3 chooses a permanent magnet synchronous motor, while Weilai ES8 Model X uses an asynchronous motor. What is the difference between these two motors?

First of all, the definitions of the two motors are different. The motor generates a magnetic field by energizing, and cuts the rotating magnetic induction line through the so-called rotor inside the electronic equipment, thus generating electricity. When the speed of the rotor is consistent with the speed of the magnetic field, we call it a synchronous motor with permanent magnets, and when the speed of the rotor is lower than the speed of the magnetic field, we call it an asynchronous motor. Judging from the energy conversion rate, these two motors are also different. The conversion efficiency of permanent magnet synchronous motor is higher than that of synchronous motor.

Permanent magnet synchronous motor has a very important feature, that is, the energy conversion rate is very high, up to 94%. However, the energy conversion rate of asynchronous motor is low, up to 90%. But in fact, compared with traditional fuel vehicles, the conversion efficiency of these two motors is also very high, and the highest conversion efficiency of the engine of traditional fuel vehicles is 42%. Their speed ranges are very different, one is wide and the other is narrow.

Permanent magnet synchronous motor can meet the needs of vehicles driving on complex roads. Simply put, it can maintain a high energy conversion rate in various departments. Asynchronous motor can only improve the conversion efficiency when it is driven at high speed, but when it is driven at low speed, it consumes much more power than permanent magnet synchronous motor, and its application range is narrow.

Judging from the size of the two motors, the two electrodes are very different, one is fat and the other is thin.

Compared with asynchronous motors, permanent magnet synchronous motors are smaller and lighter. Small size can bring more advantages to new energy vehicles, and more independent space can be set in the car and trunk. Putting it on the chassis can also expand the space and increase the battery, which is beneficial to the lightweight design of the vehicle.