Optimum design of a Novel Dual-PM Axial-Field Flux Reversal Machine for an In-wheel Direct-Drive Electric Vehicle Application

This article presents a novel dual permanent magnet axial field flux reversal machine (dual-PM AFFRM) with a single stator and a single rotor for an In-wheel direct drive electric vehicle (EV) application. The topology and operation principle of the machine were explained, and the impacts of using dual PM configuration on the airgap flux density harmonics were revealed using a simple magnetomotive force (MMF)-permeance model. To obtain the optimum torque characteristic of the machine and reduce the computational effort, the Taguchi method is employed. The electromagnetic performances of the optimized design are assessed via the 3-D finite element method (FEM). The outcomes show that the optimized machine offers high torque capability, low torque ripple, and good flux weakening capability. In addition, the results of a comparative study among eight different traction machines reveal that the dual-PM AFFRM offers the highest torque density with high aspect ratio, and high torque constant, which are crucial for direct-drive In-wheel EV applications.