Synchronous Motors: Basics

Synchronous ac motors are constant-speed electric motors and they operate in synchronism with mains line frequency.
The speed is determined by the number of pole pairs and is always a ratio of the line frequency.

JE offers a range of claw pole synchronous motors, which design is same as for stepper motors.

Depending from number of claw poles, magnet pole pairs and line frequency 50 or 60Hz, the speed is 250 to 720 rpm.

For comparison, this picture shows coil currents which are generated by an electronic driver circuitry to a stepper motor.

This picture shows coil currents generated by mains sine wave 50 or 60Hz.

For defined direction of rotation, a capacitor must be switched in series to one of the coils.

Synchronous Motors 

 

See below another basic construction of synchronous motor.
It is a 2pole motor (speed 3000rpm at 50Hz) with one coil only.
A defined starting direction of rotation is achieved by the shape of stator core (reluctance effect).

 Synchronous Motors