Influence of winding design on losses in brushless AC IPM propulsion motors

This paper presents an analysis of loss in a brushless AC interior permanent magnet (IPM) propulsion motor with an emphasis on the high speed, field weakened region of the operating envelope. The loss distribution during short circuit operation is used as a simple measure for appraising field weakened performance. It is demonstrated the choice of winding configuration can have a significant impact on stator iron and rotor loss. The losses resulting from alternative fully pitched and short pitched windings are compared using three-dimensional finite element modelling. The theoretical loss predictions are experimentally validated on a prototype motor showing good agreement. A lumped-parameter thermal model of the motor is also developed and is used to confirm the estimated distribution between stator copper, stator iron, rotor iron and magnet losses.