General Analytical Model of Magnet Average Eddy-Current Volume Losses for Comparison of Multiphase PM Machines With Concentrated Winding

This paper studies magnet eddy-current losses in permanent-magnet (PM) machines with concentrated winding. First, space harmonics of magnetomotive force (MMF) and their influence on magnet losses in electrical machines are investigated. Second, an 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 exhibited according to the ratio between each harmonic wavelength and magnet pole width. Then, various losses submodels are deduced. Using this analytical model, magnet volume losses for many slots/poles combinations of three-, five-, and seven-phase machines with concentrated winding are compared. This comparison leads to classify combinations into different families, depending on their magnet losses level. Finally, in order to verify the theoretical study, finite-element models are built and simulation results are compared with analytical calculations.