Comparison and Investigation of Outer-Rotor Flux-Modulated Permanent Magnet Motor with Different Pole Ratios and Rotor Poles

In this paper, a new method based on the investigation of pole ratio (PR) and rotor poles is proposed for pole-slot combination design of an outer-rotor flux-modulated permanent magnet (OR-FMPM) motor to improve output torque and reduce permanent magnet (PM) eddy current loss. Firstly, through the analytical method, the relationships of the PR and the rotor poles with output torque and PM eddy current loss, respectively, are derived. Then, the performances of topologies with different PRs and rotor poles, respectively, are compared and investigated by finite element analysis (FEA). The result reveals that the PR and the rotor poles significantly influence the performance. Subsequently, the optimal pole-slot is selected for the OR-FMPM motor, and other basic performances are evaluated, including the flux distribution and flux density distribution, no-load back electromotive force (EMF), etc. Finally, the theoretical analysis and the simulation results verify the rationality and effectiveness of the method.