Thermal Analysis and Research of a Yokeless and Segmented Armature Axial Flux In-Wheel Motor With an Amorphous Magnetic Metal Stator

The in-wheel motor for electric vehicles is required to meet the demands for high power density and a compact axial length. Precise thermal design and effective heat dissipation are critical, as they significantly influence the reliability of vehicle operation. This paper presents a novel yokeless and segmented armature (YASA) axial flux in-wheel motor featuring a specifically designed amorphous magnetic metal stator. The electromagnetic and mechanical losses of the motor are calculated, and the thermal conduction properties of the amorphous magnetic metal stator are analyzed. Additionally, the equivalent thermal conduction coefficients for the windings and insulation are determined. A three-dimensional thermal finite element model of the motor is developed to obtain the temperature distribution. A prototype is manufactured, and an experimental platform is established to measure the temperature of each component. The measured data closely correlate with the calculated results, thereby validating the effectiveness of both the electromagnetic and thermal finite element models. The thermal characteristics of the prototype demonstrate compliance with the requirements for electric vehicles, providing valuable insights for the thermal design of the novel YASA in-wheel motor.