Torque Density Improvement in an Axial Flux Permanent Magnet Machine with Trapezoidal Cross-Section Rotor and Dual Three-Phase Windings

Abstract

This paper presents the design of a novel axial flux permanent magnet synchronous machine (AF-PMSM) featuring tooth-coil winding and spoke-type magnets. The primary objective is to leverage these design features to enhance torque density by modifying the geometry of the rotor yoke. A 10-pole 12-slot machine was optimized using quasi-3D finite element analysis (FEA) and genetic algorithm optimization. The optimal design was evaluated with two different winding configurations. The results demonstrate that strategically varying the rotor height from the inner to the outer diameter increases the machine torque density, with an optimal configuration occurring when the inner diameter height is about half that of the outer diameter. A dual three-phase winding arrangement further boosts torque output, yielding a slight additional gain in torque density. An experimental prototype was presented as a proof-of-concept.