Design and analysis of a novel flux reversal machine

In this paper, a novel flux reversal machine (FRM) is proposed to achieve a larger torque density and a smoother torque waveform than the conventional FRM. The proposed FRM have the same combinations of stator and rotor slots, winding pole pair and PM usage, but different PM arrangement with the conventional FRM, i.e. in the conventional FRM, a pair of PMs is mounted on the surface of each stator teeth, while the PMs of the proposed FRM are uniformly attached to the entire inner surface of the stator. First, the origination from the conventional FRM to the proposed FRM is introduced. Then, the effects of the rotor slot number, split ratio, stator/rotor slot opening ratio, PM thickness and pole arc on average torque and cogging torque are investigated and analyzed, which give a reasonable prediction for maximum achievable power density and minimum possible cogging torque of the proposed FRM. Moreover, the proposed FRM is compared to a conventional FRM in terms of back-EMF, cogging torque, rated torque, torque ripple and overload capabilities. Finally, a 12-stator-slot/17-rotor-slot FRM prototype is built to verify the theoretical analyses.