The working principle of asynchronous motors

Place a freely rotating squirrel cage like short-circuit winding in a rotatable horseshoe magnet. When the horseshoe magnet is rotated, the squirrel cage will follow it in the same direction. This is because after the magnet rotates, its magnetic line of force cuts through the conductor of the squirrel cage, generating an induced electromotive force in the conductor. According to the right-hand rule, the direction of the electromotive force can be determined (the direction of the electromotive force in the upper half of the squirrel cage conductor faces inward, represented by the symbol , and the electromotive force in the lower half of the conductor faces outward, represented by the symbol ⊙). As the squirrel cage conductor is short circuited, there is current flowing through the conductor under the action of the electromotive force, The direction of current is the same as the direction of electromotive force.

The current in a charged conductor is subjected to a force in a magnetic field, and the direction of force F can be determined by the left-hand rule. The upper and lower halves of a squirrel cage motor are subjected to force in opposite directions and of equal magnitude, thus forming a torque. This torque will cause the squirrel cage to rotate in the direction of the magnetic field, which is the simple operating principle of an asynchronous motor.