Stator-Slot/Rotor-Pole Pair Combinations of Flux-Reversal Permanent Magnet Machine

In this paper, the stator-slot/rotor-pole pair combination principle of flux-reversal permanent magnet machines is proposed considering both magnetization modes and magnetic flux leakage effects. First, arbitrary slot/pole combinations with different magnetization modes exhibit compensation effect or are not investigated and the reason why some special slot/pole combinations without compensation effect still exhibit a rather sinusoidal back electromotive force (EMF) is unveiled. Then, the winding factor of back EMF is given and the effect of slot/pole combination on electromagnetic performances is investigated. Finally, specific slot/pole combinations exhibiting fault-tolerant capability are also discussed. Correspondingly, the experiments are constructed to verify the theoretical analysis. Finally, a determination principle for reasonable slot/pole combining is summarized, where both the magnetization mode and coil pitch can be obtained aiming at maximum back EMF. Additionally, the proper slot/pole combinations suitable for different load conditions and fault-tolerant applications are also highlighted.