Concept and Electromagnetic Design of a New Axial Flux Hybrid Excitation Motor for In-wheel Motor Driven Electric Vehicle

In this paper, a new axial flux hybrid excitation motor (AFHEM) with core-wound coils is presented. The structural description and magnetic circuit principle of the AFHEM are introduced. The advantages that are obtained by adopting such stator construction with core-wound coils and introducing of field windings on the stator are self-evident, and the mechanical robustness of the magnetic structure are highlighted. This paper discusses the designed features of AFHEM for application of in-wheel motor drive, and motor performances such as efficiency, torque density and torque control are evaluated for a comparison with those of conventional PM machines. A prototype machine model for wheel hub integration is built. Fundamental performances of the AFHEM are investigated in detail by using finite-element analysis (FEA), such as magnetic field distribution, excitation regulation property, torque-current ratio and torque performance. The comprehensive performance result of AFHEM is suitable for wheel hub integration.