A Novel Dual-Rotor, Axial Field, Fault-Tolerant Flux-Switching Permanent Magnet Machine With High-Torque Performance

This paper proposes a novel dual-rotor, axial field, fault-tolerant flux-switching permanent magnet machine (FSPMM) with high-torque performance for direct-drive applications, in which the phase-group concentrated-coil windings and the unaligned arrangement of the two rotors are used. The adoption of the phase-group concentrated-coil windings is made to obtain a unity displacement winding factor, and to enhance the flux-focusing effects together with the use of a spoke-type PM configuration. The unaligned arrangement of the two rotors will help to achieve increased flux magnification and also to suppress the cogging torque and the torque ripple. In particular, the proposed configuration for FSPMMs exhibits the advantage of fault tolerance, benefiting from the electromagnetic isolation of phases and a dual three-phase channel of supply. The operating principle and the design criteria of the proposed FSPMM are discussed in detail. To highlight the advantages of the proposed FSPMM, two conventional FSPMMs are adopted for comparison under the same operating conditions based on a 3-D finite-element method. As a result, it is demonstrated that the proposed FSPMM exhibits significantly improved performance with not only higher torque (power) density but also lower cogging torque and torque ripple, compared with the conventional FSPMMs.