Modeling and Analysis of Dual-Winding Bearingless Flux-Switching Permanent Magnet Motor Considering Magnetic Saturation Based on Subdomain Model

Dual-winding bearingless flux-switching permanent magnet machine (BFSPMM) is composed of power winding and suspension winding. The permanent magnet and the power winding provide a biased air gap magnetic field, and the suspension winding generates an air gap modulation magnetic field. The structure of stator and rotor are double salient poles. This paper proposes a subdomain model for the on-load field prediction in dual-winding BFSPMM. In the developed model, the field domain is divided into seven types of subdomains, viz. rotor slot, internal air gap, stator slot, permanent magnet slot upper layer, permanent magnet slot lower layer, permanent magnet, and external air gap. The electromagnetic parameters of the motor are analyzed, including air gap flux density, flux linkage, back-EMF, suspension forces, and electromagnetic torque. Based on the principle of conservation of magnetomotive force, a distributed equivalent magnetic circuit model is proposed to compensate for the magnetic saturation. Finally, the analytical predictions are verified by finite-element analysis and prototype experiments.