Permanent magnet synchronous motors are divided into two types: one achieves synchronization through variable frequency speed control, and the other achieves synchronization through asynchronous starting.

Due to the large rotor inertia, the magnetic field rotates too fast.

The permanent magnet synchronous motor cannot be started directly with three-phase AC; the stationary rotor cannot follow the magnetic field's start.

Variable frequency speed controller mode.

The power supply of the permanent magnet synchronous motor uses a variable frequency controller. During startup, the frequency output from the inverter starts from 0 and continuously rises to the grid frequency. The motor speed synchronously rises with the inverter output frequency. The inverter output frequency can change the motor speed, making it a very good variable frequency speed control motor.

How to start asynchronously.

Through the interaction of the stator winding, rotor squirrel cage winding, and permanent magnet, the starting and operation of the permanent magnet synchronous motor are formed.

Add a cage-type winding on the permanent magnet rotor, and directly supply three-phase AC power in situations where speed control is not needed.

The stator winding generates a rotating magnetic field through three-phase AC in a stationary state; the rotating magnetic field is equivalent to the rotor's rotation, inducing current in the cage winding, forming a rotating magnetic field of the rotor. The interaction of the two magnetic fields generates torque, causing the rotor to start rotating from a stationary state.

The speed of the rotor's rotating magnetic field is not equal to the speed of the stator's rotating magnetic field, thus generating alternating torque.

The rotor winding does not generate induced current; only the permanent magnet on the rotor generates a magnetic field. When the rotor's rotating magnetic field is almost synchronized with the stator's rotating magnetic field, a driving torque is generated!

Therefore, the rotor winding achieves startup. After startup, due to the interaction of the magnetic fields of the permanent magnet and the stator winding, the rotor winding no longer plays a role in generating torque.