Interior permanent magnet motor

Abstract

An interior permanent magnet motor comprising a rotor having a set of permanent magnets placed within the interior of the rotor and a stator which surrounds the rotor and has a set of stator teeth defining slots between adjacent teeth. The stator also includes a plurality of stator windings that extend around the teeth and within the slots, the rotor and stator defining an airgap there between, in which an outer peripheral surface of the rotor that faces the stator across the airgap is provided with a respective eccentric bulge in the region of each rotor magnet. The bulge has a part-elliptical shape, the centre of the circumference of the bulge lying on or close to an axis that passes through the axis of rotation of the rotor and through a point on or close to the circumferential centre of the associated magnet, and in which the two ends of the part-elliptical bulge respectively connect to a region of the periphery that interconnects to an adjacent bulge, in which the dimensions of the bulge are selected so as to optimise the motor in terms of minimising variations in cogging torque that arise due to geometric manufacturing errors.

Dependencies are inferred from the claim text.