Exploration of Rotor Topology Evolution Mechanism in the Stator-PM Machines

During the optimization of rotor configurations in the flux-switching permanent magnet (FSPM) machine, the contradiction between the pulsating torque suppression and the average torque improvement is a challenging aspect to be addressed. Accompanied by it is the absence of theoretical guidance on rotor design according to torque performance requirements. To address them, by virtue of general airgap field modulation theory (GAFMT), this paper focuses on investigating rotor topology evolution mechanisms that is not only applicable to FSPM machine, but also to flux-reversal PM (FRPM) machine and doubly-salient PM (DSPM) machine. The study proceeds with an analysis of impacts of PM placements on the rotor configurations in 12-stator-slot/10-rotor-pole stator-PM machines. Subsequently, a two-dimensional fast Fourier transformation (2D FFT) is employed to elucidate the trade-off between the increase of average torque and the decrease of pulsating torque. Thirdly, the concept of amplitude modulation is introduced, and under its guidance, two rotor configurations are designed according to their respective objective functions. Multi-objective optimization (MOP) is then applied to enhance the torque performance and evaluate the effectiveness of rotor topologies. Finally, the rotor topology evolution mechanism of stator-PM machines is verified through finite element analysis (FEA) and experimental results, specifically in the case of FSPM machines.