Effect of Magnet Materials on Designing of a High Power-Low Voltage Permanent Magnet Flux Switching Motor for Automotive Applications

Abstract

This work investigates the effect of using different permanent magnet (PM) materials on designing a flux switching permanent magnet (FSPM) motor for automotive applications. The investigation spans four different magnet materials; neodymium magnets (Nd), samarium cobalt (SmCo), dysprosium free magnets (Dy-free) and ferrite magnets. The initial design is based on the Nd magnets. SmCo, Dy-free and ferrite magnets are then used to replace the Nd magnets. The main scope of this work is to study the key design parameters to compensate for the disparity in the PM energy density. Considering the application constrains, the excitation current, the inverter voltage and the machine volume, a group of parameters has been analysed to enhance the overall performance for the different magnet materials. The key design parameters used to recover the PM energy reduction are the number of turns per coil and the split ratio. The machine performance is analysed using a finite element (FE) model. Different performance parameters, including the predicted output torque, terminal voltages, torque ripples, magnet losses, power factor, field weakening capability and probability of local demagnetisation have been compared and analysed.