Performance Improvement of Spoke Array Permanent Magnet Vernier Motor for Small Electric Vehicles Application

ABSTRACT

The permanent magnet vernier machine (PMVM) offers several advantages, including higher torque density, lower cogging torque, a simpler and more robust structure and improved efficiency compared to other permanent magnet‐based topologies. This machine is a suitable candidate for use in small electric vehicles such as e‐bikes, scooters and motorcycles. This paper evaluates various configurations of permanent magnet vernier motors designed for a 450 W electric scooter. The proposed configuration employs an outer‐rotor spoke‐type arrangement, in which the central magnets are angularly shifted relative to the side magnets. The shifted spoke configuration is modelled using a magnetic equivalent circuit (MEC) and subsequently optimised through sensitivity analysis of its parameters. Finally, a prototype of the proposed structure is developed, and its performance is compared with finite element method (FEM) and analytical modelling results. The proposed array demonstrates higher power factor, increased torque density and reduced cogging torque compared to the conventional design. Furthermore, the mechanical robustness of the rotor is enhanced owing to the inclusion of an iron bridge structure.