Principle of permanent magnet synchronous motor

Permanent magnet synchronous motor is a synchronous motor that uses permanent magnet as the magnetic field source. Its core components include stator, rotor and controller. The stator is the fixed part of the motor, usually composed of iron core and winding; the rotor is the rotating part of the motor, usually composed of permanent magnet and shaft; the controller is the control core of the motor, responsible for real-time monitoring and control of the running status of the motor.

 1. Working principle

When the permanent magnet synchronous motor is powered on, the stator winding generates a rotating magnetic field. The speed of this rotating magnetic field, that is, the synchronous speed, is related to the power supply frequency and the number of motor pole pairs. The permanent magnets on the rotor are attracted by the rotating magnetic field of the stator and begin to rotate synchronously with the rotating magnetic field. This characteristic of synchronous rotation is the origin of the name of the permanent magnet synchronous motor. The rotation speed of the rotor is exactly the same as the rotation speed of the stator magnetic field, which is the main difference between permanent magnet synchronous motors and asynchronous motors (such as induction motors).

2. Control principle

The control of permanent magnet synchronous motors is mainly achieved through controllers. The controller realizes the functions of starting, braking, speed regulation and protection of the motor by adjusting parameters such as current, voltage and frequency. Common control methods include vector control, direct torque control and space vector pulse width modulation (SVPWM). These control strategies can accurately adjust the torque and speed of the motor so that it can maintain efficient operation under various working conditions.

 Advantages of permanent magnet synchronous motors

1. High efficiency

The biggest advantage of permanent magnet synchronous motors is high efficiency. Since permanent magnet synchronous motors use permanent magnets as magnetic field sources, the magnetic resistance of the magnetic circuit is greatly reduced, thereby reducing the loss of magnetic flux. In addition, the air gap of permanent magnet synchronous motors is small, which reduces the leakage of magnetic flux. These factors make the efficiency of permanent magnet synchronous motors much higher than that of traditional asynchronous motors.

2. High performance

Permanent magnet synchronous motors have the characteristics of high performance. Since the magnetic field of the permanent magnet synchronous motor is generated by permanent magnets, the strength and direction of the magnetic field can be precisely controlled. This allows the permanent magnet synchronous motor to achieve high-precision speed regulation and positioning functions. In addition, the starting and braking process of the permanent magnet synchronous motor is very smooth, without the starting and braking impact of the asynchronous motor.

3. High reliability

The permanent magnet synchronous motor has high reliability. Since the structure of the permanent magnet synchronous motor is relatively simple and there are no complex components such as carbon brushes and commutators, the failure rate is low. In addition, the temperature of the permanent magnet synchronous motor is low and the heat dissipation performance is good. Its brushless structure can reduce mechanical wear, which is conducive to improving the reliability and service life of the motor and reducing maintenance costs.

4. Low noise

The permanent magnet synchronous motor has the characteristics of low noise. Since the air gap of the permanent magnet synchronous motor is small and the leakage of magnetic flux is less, the electromagnetic noise is low. In addition, the starting and braking process of the permanent magnet synchronous motor is very smooth, without the starting and braking impact of the asynchronous motor, thereby reducing the generation of noise.

Application of permanent magnet synchronous motor

Due to the advantages of high efficiency, high performance, high reliability and low noise, permanent magnet synchronous motors are widely used in many fields. The following are some typical application scenarios:

1. Industrial automation

In the field of industrial automation, permanent magnet synchronous motors are widely used in CNC machine tools, compressors, elevators and other equipment. Through precise control of the motor, efficient operation and stable production of the equipment can be achieved. In addition, permanent magnet synchronous motors can also realize fault diagnosis and preventive maintenance of equipment, and improve the reliability and service life of equipment.

2. Transportation field

Permanent magnet synchronous motors can be applied to the drive system and traction system of electric vehicles and rail transportation. Among them, electric vehicles are an important application field of permanent magnet synchronous motors. In electric vehicles, permanent magnet synchronous motors are used to drive the motors of cars to realize the starting, braking and speed regulation of cars. Through precise control of the motor, efficient operation and low energy consumption goals of electric vehicles can be achieved.

3. Household appliances

In the field of household appliances, such as air conditioners, refrigerators, washing machines and other equipment, permanent magnet synchronous motors are widely used. Through precise control of the motor, efficient operation and comfortable performance of the equipment can be achieved. In addition, permanent magnet synchronous motors can also achieve energy-saving operation and intelligent control of equipment, improving the user experience of the equipment.

4. New energy field

In the field of renewable energy, such as wind power generation and solar power generation equipment, permanent magnet synchronous motors are widely used. Through the precise control of wind turbines and solar generators, efficient conversion and utilization of energy can be achieved. In addition, permanent magnet synchronous motors can also realize equipment fault diagnosis and preventive maintenance, improving the reliability and service life of equipment.