Improvement of Torque Characteristic in Permanent-magnet Assisted Synchronous Reluctance Motor by Topology Optimization

Abstract

Although the rare earth material is actively applied to the electric vehicle, train, and so on, the cost of the rare earth material rises more and more. Therefore, the synchronous reluctance motor (SynRM) which does not require permanent magnet is remarkable from the viewpoint of lower price and high efficiency. However, the torque characteristic of SynRM is much lower than that of interior permanent magnet synchronous reluctance motor (IPMSM). Then, permanent magnet assisted synchronous reluctance motor (PMASynRM) which bonded magnet was attached to the rotor structure of SynRM has been proposed. Because bonded magnet is applied to PMASynRM, the manufacturing cost of PMASynRM is lower than that of IPMSM. In this paper, the structure of PMASynRM has been drastically changed by topology optimization. As the result, improvement of torque characteristic is achieved in the optimized structure.