Performance Improvement of IPMSM with Sustainable Materials

Abstract

This thesis investigates the redesign and optimization of an Interior Permanent Magnet Synchronous Motor (IPMSM) for electric vehicle traction applications using heavy rare-earth-free permanent magnet materials. The main objective is to improve demagnetization robustness under Active Short-Circuit (ASC) conditions while maintaining the required torque capability, efficiency, and cost performance. Different magnet materials, rotor topologies, and machine configurations were evaluated using finite element simulations in JMAG. The study includes topology screening, ASC analysis, preliminary parametric optimization, and full-scale optimization using a genetic algorithm approach. Based on the obtained simulation results, two candidate machine configurations were selected for further optimization and compared with the benchmark motor in terms of torque capability, efficiency, losses, material usage, and irreversible demagnetization behavior. In addition, sensitivity analysis and correlation studies were used to identify the most influential design parameters during the optimization process. The results demonstrate that suitable rotor topology selection and electromagnetic optimization can significantly improve ASC robustness and reduce demagnetization sensitivity while maintaining the required traction motor performance using heavy rare-earth-free magnet materials.

Index Terms: IPMSM, rotor topology optimization, active short circuit, demagnetization robustness, electric vehicle traction, heavy rare-earth–free magnets, finite element analysis, flux weakening, torque density