Working principle of a synchronous motor

The principle of operation of a synchronous motoris based on the interaction of the rotating magnetic field of the stator and the constant magnetic field of the rotor. The concept of the rotating magnetic field of the stator of a synchronous motor is the same as that of a three-phase induction motor.

The principle of operation of a synchronous motor is based on the interaction of the rotating magnetic field of the stator and the constant magnetic field of the rotor.

The magnetic field of the rotor, interacting with the synchronous alternating current of the stator windings, according to the Ampere's Law, creates torque, forcing the rotor to rotate (more).

Permanent magnets located on the rotor of the PMSM create a constant magnetic field. At a synchronous speed of rotation of the rotor with the stator field, the rotor poles interlock with the rotating magnetic field of the stator. In this regard, the PMSM cannot start itself when it is connected directly to the three-phase current network (current frequency in the power grid 50Hz).