Average-torque-maximization and cogging-torque-minimization of permanent-magnet-assisted synchronous reluctance motor using topology optimization

Although rare earth materials are actively utilized in permanent magnets for a wide variety of applications including electric vehicles and trains, the cost of these materials is on the rise. Therefore, the synchronous reluctance motor (SynRM) which does not require permanent magnets is remarkable from the perspective of high efficiency and low cost. However, the torque characteristic of the SynRM is much lower than that of the interior permanent magnet synchronous reluctance motor (IPMSM). Then, a permanent magnet assisted synchronous reluctance motor (PMASynRM) which bonded magnet was attached to the rotor structure of SynRM has been proposed. The manufacturing cost of the PMASynRM is lower than that of the IPMSM because a bounded magnet is utilized former. In this work, the structure of the PMASynRM has been drastically changed by topology optimization to average torque maximization and cogging torque minimization.