Comparative evaluation of different permanent magnet materials for spoke interior permanent magnet motor suitable for automotive application

Abstract

Spoke Interior Permanent Magnet Synchronous Motors (IPMSM) are regarded as a potential substitute to conventional IPMSM in electric four wheeler application due to its simple construction, wide speed torque characteristics, improved power factor, efficiency and high torque density. The traditional IPMSM employs Neodymium Ferrite Boron (NdFeB) magnets, which have high torque density. But, the problems associated with NdFeB magnets include demagnetization owing to high operating temperature, high investment cost, brittleness which leads to high stress distribution in the rotor with torque ripple, high cost of maintenance and existence of cogging torque. Therefore, this work attempts to design and analyze Spoke type IPMSM different permanent magnet materials such as Samarium Cobalt (SmCo) and Y30 type Ferrite Magnets (rare earth free magnet), to evaluate the torque density, efficiency, requirement of cooling in order to reduce thermal demagnetization, Von-Mises stress and cogging torque. The volume of the motor is varied for various permanent magnet materials. The results of this work provides insight into the various performance measures with respect to choice of different magnetic materials suited to electric four wheeler (automotive) application.