Synchronous motor with permanent magnet excitation and control of stator induced voltage by adjusting magnetic behaviour of one magnet per pole

摘要

The machine rotor consists of dynamo grade sheet (1) and two permanent magnets per pole. The thickness of the magnets is such that the magnetomotive force developed by the supplementary stator current (to control the voltage induced in the stator by the rotating magnetic field) is greater than the magnetic voltage of magnet (3) but less than the total of that and magnet (2). This magnetizes that portion of the first mentioned magnet close to the rotor centre in the same direction as, and supports, the field generated by the stator current