Open-circuit field distribution in a brushless motor with diametrically magnetised PM rotor, accounting for slotting and eddy current effects

An analytical model has been developed for calculating the open-circuit time-varying magnetic field distribution in the airgap/magnet/retaining 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 retaining sleeve and magnets. The analytically predicted time-varying field distribution in the different regions is compared with corresponding finite element predictions.