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Analysis of permanent magnet synchronous motor and AC asynchronous motor

Date:2023-08-14   Author:XINDA MOTOR

Both permanent magnet synchronous motors and AC asynchronous motors are common AC motors, and they have the following differences:

The working principle is different: there is a constant magnetic field between the rotor and the stator of the permanent magnet synchronous motor, while the AC asynchronous motor generates torque through the electromagnetic induction between the rotating magnetic field and the rotor.

Different power factor : The power factor of permanent magnet synchronous motors is usually higher than that of AC asynchronous motors, which means that permanent magnet synchronous motors can use electricity more efficiently and reduce energy loss.

The control methods are different: permanent magnet synchronous motors need to use advanced control technology to control their operation, while AC induction motors can be controlled using simpler motor starters and traditional frequency converters .

Different applicable scenarios: permanent magnet synchronous motors are suitable for high-performance application scenarios, such as electric vehicles, motor tools, high-speed motors, etc.; while AC asynchronous motors are suitable for most low- and medium-power application scenarios, such as household appliances, air conditioners, water pumps wait.

Efficiency is different: Permanent magnet synchronous motors can achieve higher efficiency during design and operation, usually reaching more than 90%. The efficiency of AC induction motors is usually between 85% and 90%.

Different starting methods: Permanent magnet synchronous motors usually need to use special starting technologies, such as voltage source inverter, direct torque control, vector control, etc. The AC asynchronous motor can use relatively simple starting technology, such as star-delta starter, autotransformer starter and so on.

Different speed ranges: Permanent magnet synchronous motors usually have a large speed range and can maintain high efficiency over a wide speed range. However, the speed range of the AC asynchronous motor is relatively narrow, and a frequency converter is usually required to realize variable speed control.

Advantages of AC asynchronous motor: good reliability; high speed performance; easy cost control. Disadvantages: low power density (larger volume at the same power level); low energy conversion efficiency (85%-90%); high energy consumption.

Advantages of permanent magnet synchronous motor: high power density; high energy conversion efficiency (90%-95%); low energy consumption. Disadvantages: Due to the addition of permanent magnets, the cost is increased; permanent magnets have the risk of demagnetization under high temperature and vibration environments.

The characteristics of the model that chooses the AC asynchronous motor:

Models that choose AC asynchronous motors tend to give priority to performance. Taking advantage of the performance output and efficiency advantages of AC asynchronous motors at high speeds, the representative model is the early Model S. Main features: When the car is running at high speed, it can maintain high-speed operation and high efficiency of electric energy usage, and reduce energy consumption while maintaining the maximum power output.

Select the characteristics of the model of the permanent magnet synchronous motor:

Models that choose permanent magnet synchronous motors tend to give priority to energy consumption, and use the performance output and efficient operation of permanent magnet synchronous motors at low speeds, which are suitable for small and medium-sized vehicles. It is characterized by small size and light weight, which can increase battery life. At the same time, it has good speed regulation performance, and can maintain high efficiency in the face of repeated start and stop, acceleration and deceleration.

In general, permanent magnet synchronous motors and AC asynchronous motors have their own advantages and limitations, and users need to choose according to actual needs.

To sum up, there are certain differences between permanent magnet synchronous motors and AC asynchronous motors in terms of working principles, power factors, control methods, and applicable scenarios. Users need to choose the appropriate motor type according to actual needs.