Development of an IPMSM for in-wheel type electric vehicles

This paper deals with a design approach to an interior permanent magnet synchronous motor (IPMSM) used in in-wheel motor drive systems of electric vehicles. The approach is divided into three parts overall. First, the constant power region of IPMSM and gear ratio are investigated in order to meet the specifications of the in-wheel motor system. Second, the range of inductance and back-EMF to satisfy the given design conditions of the IPMSM is estimated. Finally, the preliminary geometry satisfying the range is decided by PM type, current density, and fill factor and so on, and then the detailed design is carried out by means of finite element analysis in consideration of magnetic saturation.