Design Optimization of Synchronous Reluctance Motor for Reducing Iron Loss and Improving Torque Characteristics Using Topology Optimization Based on Level-set Method

Because the synchronous reluctance motor (SynRM) does not require a rare-metal-based permanent magnet (PM), the demand for SynRMs is progressively increasing because of the inexpensive design. However, due to the disuse of the PM, the average torque of the SynRM is much lower than that of an interior PM synchronous motor. Although many shapes of the flux barrier have been reported for the improvement of the torque characteristics, most of them are derived from the shape optimization method. Since the topology of the rotor and stator core is fixed during shape optimization, there is the possibility of further improving the torque performance using topology optimization (TO). Furthermore, it is very important to reduce the iron loss as well as to improve the torque characteristics to improve the SynRM efficiency. In this article, a sensitivity analysis of the iron loss using the adjoint variable method is proposed. The procedure is successfully implemented for a TO based on a level-set method, and design optimization of the SynRM for reducing iron loss as well as improving the torque characteristics is demonstrated.