Multiphase Flux-Switching Permanent-Magnet Brushless Machine for Aerospace Application

TLDR

Flux‑switching permanent‑magnet brushless machines are promising for high‑torque, robust‑rotor aerospace applications, yet prior work has examined only one‑ to three‑phase designs and must balance rotor mechanical stress with electromagnetic performance. This study compares the electromagnetic performance of three‑, four‑, five‑, and six‑phase FSPM machines for aerospace use. The authors model both all‑pole and alternate‑pole winding configurations with finite‑element analysis of EMF, inductance, cogging torque, and static torque, and assess rotor mechanical stresses, validating the results with experiments on a small‑scale five‑phase prototype. Finite‑element predictions of EM performance were confirmed by experimental measurements on the five‑phase prototype, demonstrating the accuracy of the modeling approach.

Abstract

Flux-switching permanent-magnet (FSPM) brushless machines have attracted considerable interest as a candidate machine technology for applications requiring high torque density and robust rotors. To date, published findings have focused exclusively on single- and three-phase FSPM machines. This paper investigates FSPM brushless machines of higher phase numbers by means of a detailed comparison of the electromagnetic performances of three-, four-, five-, and six-phase variants within the specific context of aerospace machine. Machines having both all poles and alternate poles wound are investigated, with the latter offering scope to reduce mutual coupling between phases so as to achieve improved fault tolerance. The finite-element (FE)-predicted electromagnetic performances in both machines, such as electromotive force waveform, winding inductance, cogging torque, and static torque, are validated by the experiments made on a small-scale five-phase FSPM machine. The nature of the machine specification requires that consideration must be given to mechanical stress in the rotor and the tradeoff with electromagnetic design considerations, notably the degree of rotor saliency which can be incorporated. Therefore, a mechanical FE study of the rotor mechanical stresses of multiphase FSPM machines is also comparatively assessed.