Design of a Dual-Set Permanent Magnet Flux-Switching Machine with Enhanced Torque Density and Fault-Tolerance Capability

In this paper, a novel dual-set permanent magnet (PM) flux-switching (DSPM-FS) machine is proposed for the improvement of torque density and fault-tolerance capability. Originating from a flux-switching permanent magnet (FSPM) machine with a U-shaped PM array, fault-tolerance stator teeth are first introduced in the stator slots to prevent the risk of short-circuit faults between coils of different phases. Subsequently, aiming to enhance the torque generation, a set of surface-mounted PM is added to the fault-tolerance teeth. Due to a parallel flux circuit, the phase flux linkage is greatly increased, further improving the no-load back electromotive force (EMF). Meanwhile, a magnetomotive force (MMF)-permeance model is established, which reveals that the amplitudes of the main working harmonics of the DSPM-FS machine are significantly elevated. Moreover, the proposed and conventional machines are comprehensively compared regarding various electromagnetic performances. Consequently, the no-load back EMF and output torque of the proposed machine are increased by 43.89% and 31.47%, respectively. Additionally, the proposed machine showcases a comparable overload performance compared to the conventional machine. Furthermore, the fault-tolerance ability and power efficiency of the proposed DSPM-FS machine also exhibit notable improvement. Finally, a prototype is fabricated and tested to verify the performance of the proposed machine.