What Is the Difference Between a Synchronous & a Non-Synchronous Electrical Motor?

Alternating current electrical motors operate by spinning a rotor with a magnetic field. Asynchronous, or induction motors, are so named because the rotor spin lags in relation to the magnetic field. Rotors in synchronous motors synchronize with the magnetic field.

Rotational Speed

Synchronous motors operate at the level of input from the source. Asynchronous motors operate near the level of input from the source.

Efficiency

Because synchronous motors synchronize with the magnetic field, they are more efficient than induction motors. Synchronous motors are required for purposes requiring more than several hundred horsepower. The induction motor has an inherent lag or magnetic slip. The magnetic slip is the difference between the rotor speed and magnetic field speed.

Magnetic Field

Induction motors use a magnetic field to induce a magnetic field in the rotor itself, which causes the rotor to turn. In a synchronous motor, the magnetic field itself causes the rotor to turn.

References

• Freescale Semi Conductor: The Electric Motor, Here and Now