The working principle of asynchronous motor:

Induction motor, also known as asynchronous motor, that is, the rotor in rotating magnetic field, in the rotating magnetic field under the action of a moment of rotation, and thus rotor rotation. The rotor is a rotatable conductor, usually in the shape of a mouse cage. Invented by Nicola Tesla, an electrical engineer in 1887.

The induced electromotive force is generated by the rotor winding the magnetic induction line through the relative motion of the rotating magnetic field (whose rotation speed is synchronous speed n1) and the rotor winding, so that the induction current is generated in the rotor winding. The induction current in the rotor winding and the magnetic field produce electromagnetic torque to rotate the rotor. Because when the rotor speed is gradually close to synchronous speed, the induction current decreases, the electromagnetic torque generated is also reduced, when asynchronous motor works as a motor, the rotor speed is less than synchronous speed. In order to describe the difference between the rotor speed n and the synchronous speed n1, a slip ratio (slip) is introduced.