The difference between permanent magnet synchronous motor and three-phase asynchronous motor

　　The biggest difference between a permanent magnet synchronous motor and an asynchronous motor is whether the rotor speed of the two is consistent with the magnetic field speed of the stator rotation.If the speed of the rotor is the same as the speed of the stator, it is called a synchronous motor.

　　In terms of performance parameters and applications, there is a big difference between the two.

　　The difference between permanent magnet synchronous motor and asynchronous motor

　　1.Speed ​​difference between synchronous motor and asynchronous motor

　　In an asynchronous motor, the stator is fed with alternating current to generate a rotating magnetic field, and the rotor is induced to generate a magnetic field.In this way, the two magnetic fields cause the rotor to follow the rotating magnetic field of the stator.

　　The rotating magnetic field of the rotor is slower than that of the stator, and it is slippery and asynchronous, so it is called an asynchronous motor.

　　The rotor of a permanent magnet synchronous motor is artificially added with a direct magnetic field current to form a constant magnetic field, so that the rotor and the rotating magnetic field of the stator are synchronized, which is called a permanent magnet synchronous motor.

　　Second, the structure and principle of synchronous motors are the same as asynchronous motors

　　The stator windings of synchronous motors and asynchronous motors are the same, and the main difference lies in the structure of the rotor.

　　The rotor of the synchronous motor has a DC excitation winding, so an external excitation power supply is required to introduce current through the slip ring;

　　The rotor of an asynchronous motor is a short-circuit winding, which generates current through electromagnetic induction.

　　Asynchronous motors are simple, low cost, easy to install, use and maintain, so they are widely used.Disadvantages: low efficiency and low power factor are not conducive to the power grid. The high efficiency of the synchronous motor is a capacitive load, which can improve the power factor of the power grid. It is usually used in large-scale industries and mining industries.

　　Third, the difference between the structure and characteristics of synchronous motors and asynchronous motors

　　Fourth, the difference between the use of permanent magnet synchronous motors and three-phase asynchronous motors

　　Synchronous motors are mainly used in large generators; asynchronous motors are almost all used in electric motors.

　　Synchronous motors can flexibly adjust the power factor through excitation; the power factor of asynchronous motors is not adjustable, so in some large factories, when asynchronous motors are more used, synchronous motors can be added as cameras to adjust the distance between the factory and the grid Power factor of the interface.

　　However, due to the high cost of synchronous motors, the maintenance workload is large. Now, capacitors are usually used to compensate for the power factor.

　　Since synchronous motors have field windings and slip rings, the operator needs to have a higher level to control the excitation.In addition, compared with the maintenance-free operation of asynchronous motors, the maintenance workload is large; therefore, when it is used as a motor, most asynchronous motors have now been selected.

　　Fifth, the difference between the speed adjustment of synchronous motors and asynchronous motors

　　There are five basic speed regulation methods for asynchronous motors: variable pole pair P, variable frequency f, variable slip ratio S, variable stator voltage and rotor circuit series resistance.

　　There are two main methods of basic speed regulation for synchronous motors: the number of pole pairs P and the frequency f.

　　The above is the difference between permanent magnet synchronous motor and three-phase asynchronous motor. If you have different opinions, welcome to communicate with me!