Efficient Design and Material Strategies for High Power Density Axial Flux Permanent Magnet Motors

This paper explores design adjustments to enhance the efficiency with regards to co-design parameters of high-power motors of an axial flux yokeless and segmented armature (YASA) topology. The study examines the benefits and drawbacks of implementing tooth tips on the stator teeth. In particular, this paper proposes an alternating tooth tips arrangement that can still be implemented with pre-formed coils. For the motor under study, the alternating tooth tips can slightly increase efficiency relative to an open-slot design. Using soft magnetic composite tooth tips affixed to the teeth in a more conventional arrangement would provide even more efficiency, but would also increase manufacturing complexity. This paper also evaluates employing silicon or cobalt steel for the stator teeth with the same design; cobalt steel can boost the motor performance in comparison to grain oriented M6 material. Additionally, this paper discusses further modifications to the motor design regarding the tooth wound winding fabrication methods and tolerances. The manufacturability challenges and opportunities of the additive manufactured windings and edge bent windings with regards to their impact on toque production are provided, and pictures of the prototyped windings are shown to compare their thermal interfaces for the thermal management system functionality.