Ferrite Assisted Synchronous Reluctance Motor Design, Manufacturing and Material Influence on Motor Characteristics

Synchronous permanent magnet machines are gaining interest over the last twenty years. The best torque density and efficiency is achieved with synchronous motors using the rare-earth, usually neodymium (NdFeB) magnets. However, the price of a NdFeB magnets is rising, therefore the research in ferrite assisted synchronous motors has began. Ferrite surface and interior permanent magnet (SPM) motors suffer from low air gap flux density, thus low electromagnetic torque. The ferrite assisted synchronous reluctance motor (PMASR) compensate the lower torque created by permanent magnets with reluctance torque, developed by rotor magnetic saliency (difference between inductances in d- and q-axis). This paper deals with basic characteristics of PMASR, electromagnetic design process and results evaluation. This paper also proposes research on causes for unsatisfactory prototype characteristics. Each discovered manufacture drawback is discussed and implemented into either the FEA model or post-processing and compared with the measured data hereafter.