ANALYTICAL MODELING OF EDDY-CURRENT LOSSES CAUSED BY PULSE-WIDTH-MODULATION SWITCHING IN PERMANENT-MAGNET BRUSHLESS DIRECT-CURRENT MOTORS

An analytical approach is developed to predict the inverter high frequ ency pulse width modulation (PWM) switching caused eddy-current losses in a permanent magnet brushless de motor. The model uses polar coordi nates to take curvature effects into account, and is also capable of i ncluding the space harmonic effect of the stator magnetic field and th e stator lamination effect on the losses. The model was applied to an existing motor design and was verified with the finite element method, Good agreement was achieved between the two approaches. Hence, the mo del is expected to be very helpful in predicting PWM switching losses in permanent magnet machine design.