Minimization of Rare-Earth Permanent Magnets and Demagnetization Risk in PM-assisted Synchronous Reluctance Motor with Blended Magnets

Abstract

This paper analyzes the topology optimization for minimization of rare-earth permanent magnets and demagnetization risk in 2-layer and 3-layer U-shaped Permanent Magnet assisted Synchronous Reluctance Motor (PMaSynRM) with blended magnets. The blended magnet approach utilizes four magnet combinations using rare-earth free magnets (NdFeB), Dysprosium-free NdFeB, Ferrite and Iron Nitride magnets with the objective of reducing the usage of rare-earth permanent magnets in the designs. The multi-objective optimization algorithm based on Differential Evolution (DE) serves as the global search engine to generate the optimum designs satisfying the defined objectives and constraints based on baseline 2-layer V-shaped Chevy Bolt traction motor. The demagnetization risk assessment is computed for the optimal designs at extreme temperatures of -20°C and 150°C for all the magnet combinations. The designs with significant demagnetization risk are further optimized and the performance metrics for the modified designs in comparison with initial designs are highlighted. The results indicate the performance advantages of optimized topology.