What are the structural differences between synchronous motors and asynchronous motors?

Both synchronous motors and asynchronous motors belong to AC motors, and their armature (usually specified sub) structures are the same. The biggest difference in structure lies in the different rotor structures.

The rotor of a synchronous motor is made of a magnet or a ferromagnetic material with asymmetric magnetic circuits on the AC/DC axis (reluctance rotor). Magnets can be either electromagnets or permanent magnets, and the synchronous motor of the electromagnet rotor is called an electrically excited synchronous motor; A synchronous motor with a permanent magnet rotor is called a permanent magnet motor; A synchronous motor with a reluctance rotor is called a reluctance synchronous motor.

The rotor of an asynchronous motor is either a squirrel cage rotor or a wound rotor.

For electric motors, the stator magnetic field and rotor magnetic field of synchronous motors are relatively independent and can be powered separately or by the stator, with the rotor using permanent magnets; For asynchronous motors, it is common to see stator power supply and rotor squirrel cage structure. The motor generates a rotor magnetic field through passive induction electromotive force, which is closely related to the stator magnetic field.