Types of Synchronous Motor

Definition of Synchronous Motors

Synchronous motors are electric motors that rotate at a speed directly proportional to the frequency of the supply current.

Non Excited Synchronous Motors

These motors use external magnetic fields to magnetize a steel rotor, achieving synchronization without additional electrical excitation.

Hysteresis and Reluctance Motors

Types of non-excited synchronous motors that use different principles (hysteresis losses and magnetic reluctance) to achieve and maintain synchronous speed.

Permanent Magnet Synchronous Motors

The rotor is made up of permanent magnets. They create a constant magnetic flux. The rotor locks in synchronism when the speed is near synchronous speed. They are not self-starting and need electronically controlled variable frequency stator drive.

Direct Current Excited Motor

Direct current excited synchronous motors require a DC supply to the rotor to create the magnetic field. These motors have both stator and rotor windings and can feature cylindrical or salient pole rotors. They are not self-starting, so they use damper windings to start as induction motors before reaching synchronous speed.

Current Excited Synchronous Motors

These motors need a DC supply to the rotor windings to generate the magnetic field and often use damper windings to start as induction motors before reaching synchronous speed.