Induction motors, also known as "asynchronous motors," are devices that place the rotor in a rotating magnetic field and obtain a rotational torque under the action of the rotating magnetic field, thereby causing the rotor to rotate. The rotor is a rotatable conductor, usually in the shape of a squirrel cage. Invented by electrical engineer Nikola Tesla in 1887. The entry introduces the concept, inventor, working principle, basic structure, working mode, braking mode, asynchronous characteristics, specifications, and fault inspection of induction motors.

The relative movement of an induction motor through the rotating magnetic field generated by the stator (its rotational speed is synchronous rotational speed n1) and the rotor winding. The rotor winding cuts the magnetic induction line to generate an induced electromotive force, thereby generating an induced current in the rotor winding. The induced current in the rotor winding interacts with the magnetic field to generate electromagnetic torque, causing the rotor to rotate. As the rotor speed gradually approaches the synchronous speed, the induced current gradually decreases, and the resulting electromagnetic torque also decreases accordingly. When the asynchronous motor operates in the motor state, the rotor speed is less than the synchronous speed. In order to describe the difference between rotor speed n and synchronous speed n1, a slip rate is introduced.