AC Losses in High Frequency Electrical Machine Windings formed from Large Section Conductors

In the design of compact, power dense electrical machines found in automotive and aerospace applications it may be preferable to accept a degree of eddy current loss within the winding to realise a low cost high integrity winding. Commonly adopted techniques for analysing AC effects in electrical machine windings tend only to be applicable where the conductor dimensions are smaller than the skin depth and for ideally transposed windings. Further the temperature variation of AC losses is often overlooked. In this paper a more general approach is proposed based on an established analytical model and is equally applicable to windings where the conductor size greatly exceeds the skin depth. The model is validated against test measurements and FE analysis on representative single layer winding arrangements. A case study is used to illustrate the application of the proposed analytical method to the coupled electromagnetic and thermal modelling of a typical slot winding.