Investigation of Proximity Losses in a High Speed Brushless Permanent Magnet Motor

This paper presents a finite element investigation into the proximity losses in brushless AC permanent magnet motors used in hybrid/electric vehicle applications. The proximity effect in winding conductors is as a result of eddy-currents caused by magnetic fields generated by nearby conductors. This paper considers the influence of the conductor shape and disposition on the losses for a given stator lamination. Several structures of the winding are analysed and compared in respect to the loss and AC resistance. The analysis shows that the proximity losses can be significantly reduced through an appropriate choice of conductor shape and winding technique. The calculated results have been validated experimentally on the machine prototype for three different winding arrangements