Analytical model of magnet eddy-current volume losses in multi-phase PM machines with concentrated winding

This paper studies magnet eddy-current losses in permanent magnet (PM) machines with concentrated winding. First of all, space harmonics of magnetomotive force (MMF) and their influence on magnet losses in electrical machines are investigated. Secondly, analytical model of magnet volume losses is developed by studying the interaction between MMF harmonics wavelengths and magnet pole dimensions. Different cases of this interaction are studied according to the ratio between each harmonic wavelength and magnet pole width (following flux density variation). Then various losses sub-models are deduced. Finally, using this analytical model, magnet volume losses for many slots/poles combinations of 3, 5, and 7 phase machines with concentrated winding are compared. This comparison leads to classify combinations into different families depending on their magnet losses level. Besides, in order to validate the theoretical study, Finite Element models are built and simulation results are compared with analytical calculations.