OPEN-CIRCUIT FIELD DISTRIBUTION IN A BRUSHLESS MOTOR WITH DIAMETRICALLY MAGNETIZED PM ROTOR, ACCOUNTING FOR SLOTTING AND EDDY-CURRENT EFFECTS

An analytical model has been developed for calculating the open-circui t time-varying magnetic field distribution in the airgap/magnet/retain ing sleeve region of a brushless permanent magnet motor equipped with diametrically magnetised magnets. It accounts for the stator slotting and curvature, as well as for parasitic eddy currents induced in the r etaining sleeve and magnets. The analytically predicted time-varying f ield distribution in the different regions is compared with correspond ing finite element predictions.