Cogging Torque Reduction of Axial-Modular Flux Switching Permanent Magnet Machine by Module Combination Technique

Flux switching permanent magnet (FSPM) machine exhibits high-cogging torque due to the doubly salient topology and high air gap flux density. This article proposes a new axial-modular FSPM (AM-FSPM) machine, which has an improved torque capability and the potential of cogging torque suppression by the module combination technique. The cogging torque analytical expression of the machine with axial-modular topology is derived based on a magnetomotive force-permeance model. Then, the AM-FSPM machines are divided into two types by the combinations of stator-slot and rotor-pole, named fundamental harmonic offset naturally (HON) and fundamental harmonic offset manually (HOM). In addition, four approaches are investigated to reduce cogging torque by changing modular magnetomotive force and changing modular permeance. It can be concluded that the modular rotor tooth combination (RTC) method has the most attractive torque performance among the four methods. Finally, the effectiveness of the proposed approaches is verified by the 3-D finite element analysis (FEA) and experimental results.