ROTARY PERMANENT MAGNET ELECTRIC MOTOR WITH VARYING AIR GAP BETWEEN INTERFACING STATOR AND ROTOR ELEMENTS

摘要

A permanent magnet motor is configured with selective variation of the radia l distance between an interfacing pair of rotor permanent magnet and stator po le along the circumferential length of the pair. The effects of cogging torque on the overall torque signature can be controlled by setting an appropriate air gap variation profile. The stator pole and rotor magnet surfaces may be slop ed with respect to each other, the angle therebetween being selected to obtain desired cogging torque compensation. Other air gap variation profiles may include provision of concave surfaces, the degree of concavity being selectable.