Analysis of eddy current losses in the stator windings of IPM machines in electric and hybrid electric vehicle applications

Abstract

In this paper the eddy current losses in the windings of an IPM machine applied to electric and hybrid electric HEV applications are analysed using finite element analysis. Conductors in a slot, which form turns of a coil, are grouped in various combinations and analysed for losses. The endwinding is unaffected by skin and proximity effects and therefore modelled as a DC resistance. It was found that the end-winding resistance significantly damps the skin and proximity effects. The temperature effect on the losses has also been considered by modifying the copper conductivity. It is established that at higher winding temperatures the contribution of AC loss to the total copper loss is reduced significantly. Analysis has also been carried out for various positions of the conductors in the return slot, considering transposition in the end winding region. It is shown that through strand transposition in the end-winding region the AC losses in the stator windings can be significantly reduced.