Analysis of PM Eddy Current Loss in Four-Phase Fault-Tolerant Flux-Switching Permanent-Magnet Machines by Air-Gap Magnetic Field Modulation Theory.

In this article, the permanent-magnet (PM) eddy current loss in a four-phase fault-tolerant flux-switching PM (FT-FSPM) machine is investigated from the perspective of air-gap magnetic field modulation. It can be found that the PM eddy current loss in FT-FSPM machines results from the relative motion between air-gap field space harmonics and PMs. Some effective working harmonics produce the major PM eddy current loss. The proportion of PM eddy current loss generated by each working harmonic is studied in detail, revealing that the low-order (third) harmonic is the main factor. Then, two new structures are proposed to reduce PM eddy current loss, in which magnetic flux barriers are designed by reducing low-order harmonics from the aspect of magnetic field modulation theory. Electromagnetic performance is investigated by finite element analysis. The results show that the proposed structure is effective to suppress PM eddy current loss. Finally, an experimental test platform is established to verify the theoretical analysis results. [ABSTRACT FROM AUTHOR]