Analytical Investigation of Flux Switching PM Machines: Air Gap Flux Density Formulation

Abstract

This paper is aimed at the prediction of the electromagnetic features of the flux switching permanent magnet machines (FSPMMs), with an emphasis on the air gap flux density. The latter is firstly formulated while neglecting the slotting effect at both sides of the air gap. Doing so, three magnetomotive force (MMF) waveforms are considered. They mainly differ by the level of air gap saliency taken in account in their spatial repartition. Then, three permeance functions are incorporated, taking into account the stator slotting effect, the stator PMs effect and the rotor slotting effect. This done, the air gap flux density spatial repartition is formulated and predicted. Moreover, a comparison of the three developed analytical models leads to the selection of the more accurate one. Finally, an improved air gap flux density waveform is predicted by the incorporation of two correction factors; the first allied to the rotor position and the second allied to the saturation level. the analytically predicted results are validated by the ones yielded by a 2D finite element analysis (FEA) model.