Design and Analysis of Flux Reversal Machine Considering Slotting Effect in Permanent Magnet Excitation for Electric Vehicles

This article proposes a new design method for a flux reversal machine (FRM) for optimizing the back-electromotive force (back EMF), which takes the slotting effect in permanent magnet (SEPM) excitation into consideration. The discussed slotting effect can be obtained by shifting the centerline positions of PMs along the circumferential direction while keeping the width and the axisymmetric distribution of PMs the same. The PM centerline combination can represent the width of the slot between PMs and the positions of PMs, which is critical to magnetomotive force (MMF) distribution for back EMF optimization. The combination of PM centerline positions is the only key parameter for the back EMF optimization. It takes the advantages of a simple design process and minor structure changes for back EMF improvement. The analytical models of MMFs excited by two pairs of PMs (TPMs) and one pair of PMs (OPMs) on one stator tooth are established. The proposed SEFRMs and the conventional FRMs are designed and investigated, the electromagnetic performances are calculated and compared by finite element analysis (FEA). The results show that the proposed TPM-SEFRM with high-quality back EMF is suitable for electric vehicles (EVs). Finally, the prototype of TPM-SEFRM is manufactured and experimentally evaluated to verify the correctness of the proposed design method.