Rotor structure for reducing demagnetization of magnet in a PMASynRM with ferrite permanent magnet and its characteristics

Recently, application of permanent magnet (PM) motors has expanded remarkably because of improvements in the performance of the rare-earth PM motor. However, the use of rare-earth materials, which is an important aspect of the high-performance PM motor, should be reduced because of the high cost and the unpredictability involved in procuring such materials. The performance of motors that use rare-earth materials has reached a very high level, which will not be easy to match without such materials. In this paper, we propose a structure of high power density PM assisted synchronous reluctance motor employing the ferrite PM, that doesn't causes irreversible demagnetization of PM even in condition of the heavy flux-weakening excitation or inverter's fault. As a result, it is clarified that the proposed structure achieves high power and high efficiency performances.