Synthesis of a Flux Modulation Machine With Permanent Magnets on Both Stator and Rotor

Flux modulation permanent-magnet machines (FMPMs) operate on the magnetic gearing effect and thus can produce large torque at low rotation speed. However, the most significant drawback of many FMPMs is the low power factor. In order to further improve the torque density and power factor, this article proposes an advanced FMPM with permanent magnets (PMs) on both stator and rotor. In this article, the configuration and operation principle of the proposed machine will be introduced. Moreover, this article will also investigate the torque and power factor performances of the proposed machine under different rotor slot numbers. Then, to verify the superiority of the proposed FMPM, it is compared with a regular stator-PM FMPM and a regular rotor-PM FMPM in terms of cogging torque, back-electromagnetic force, rated torque, torque ripple, power factor, overload capability, flux weakening capability, and efficiency. Finally, a prototype of the proposed FMPM is tested, and the experimental results have verified the theoretical analyses.