Principle of Operation of Asynchronous Electric Motors

The permanent magnet is hung on a metal disk, secured by a pin in an iron bearing and the magnetic flux produced by the permanent magnet flows through the magnetic circuit series consisting of the permanent magnet, the air gaps and the iron plate. When rotating the permanent magnet, the disc that is under the magnet and also rotates. The disk follows the rotational movement of the permanent magnet due to the circulation of induced currents. These currents are induced because of the relative movement between the disk and the permanent magnet.

Induced currents tend to produce electric motors, according to Lenz’s law, a magnetic south pole on the disk under the rotating magnetic north pole of the permanent magnet, as well as a magnetic north pole on the disk under the rotating magnetic south pole of the permanent magnet. As the magnet proceeds its movement in relation to the disk, the induction of parasitic currents and magnetic poles with opposing polarities continues. In this way, the disk rotates in the same direction as the permanent magnet, but must rotate at a slower speed to have a relative velocity between the permanent magnet and the metal disk.