Design and Optimisation of Novel Outer Rotor Five‐Phase Field‐Wound Flux Switching Machine for Direct‐Drive Application

ABSTRACT

Multiphase field‐wound flux switching (FWFS) machines combine the advantages of traditional flux‐switching permanent magnet machines with the benefits of multiphase architectures, including enhanced flux controllability, high fault tolerance, increased torque density and reduced torque ripple. The doubly salient structure contributes to mechanical robustness and structural simplicity, while the utilisation of non‐overlapping windings reduces the volume of copper, which also minimises the production costs of FWFS machines. This paper presents a novel five‐phase outer rotor FWFS machine with non‐overlap windings and investigates four different rotor pole topologies. All the designs are analysed with respect to flux linkage, back‐EMF, cogging torque and electromagnetic torque. Among these configurations, the 10 slot/11 pole configuration demonstrated superior performances, exhibiting high flux linkage and average torque and minimum cogging torque. A deterministic optimisation technique was applied on 10 slot/11 pole topology to further enhance its electromagnetic performance, resulting in a 44.8% increase in average torque along with significant improvements in other parameters. The optimised design was then compared against the existing inner rotor design, showing a 96% increase in torque output. Additionally, the rotor pole designs were optimised to suit direct‐drive applications, confirming the proposed five‐phase design's potential for high speed and high reliability use in electric vehicles and renewable energy systems.