A New Parallel Magnetic Circuit Axial Flux Permanent Magnet In-Wheel Motor

Abstract

In-wheel motor presents many advantages such as high transmission efficiency, and faces many challenges such as the limited location space in electric vehicles. A compact structure and high torque density motor is required for this application. In this paper, a new parallel magnetic circuit yokeless and segmented armature (PMC-YASA) axial flux permanent magnet motor is proposed for electric vehicle in-wheel drive system. The rotor of this motor consists of tangential magnetized permanent magnets and radial Halbach array to generate axial flux together. The design of a 10 kW PMC-YASA in-wheel motor is given, which has the same volume as the YASA motor. The air gap flux density and back electromotive force are simulated. It is found that the PMC structure has lower harmonic and good magnetism gathering ability. Comparative analysis of the inductance, maximum torque and rotor loss of the PMC-YASA motor and the conventional YASA motor are carried out. The analysis results show that the PMC-YASA motor takes full use of the reluctance torque while the amount of permanent magnet is 38% smaller than that of the YASA motor. The torque density of the PMC-YASA motor is improved by 9%, and the rotor loss is decreased.