A Proposal of a Delta-Type Salient Pole Variable Flux Memory Motor Having Large Flux Barrier for Traction Applications

In this paper, a novel variable flux memory motor (VFMM) employing delta-type permanent magnet (PM) arrangement and extended flux barriers is proposed. Conventional VFMMs have three main drawbacks as follows: At first, positive and negative current pulse for magnetizing the variable flux PMs are asymmetry due to the diamagnetic field from Neodymium sintered PM as a constant flux PM. As a result of asymmetric magnetizing current, the inverter capacity is increased. Secondly, variable flux PMs are unintentionally demagnetized when applying maximum load current. Thirdly, iron loss is tend to be increased when magnetization reversal is caused by negative magnetizing current pulse because the harmonic flux becomes larger. The proposed VFMM in this paper overcomes the above challenging points at the same time because of delta-type PM arrangement and the extended flux barrier. In addition, the proposed VFMM can achieve lower iron loss and voltage than the target motor mounted in TOYOTA PRIUS fourth-generation. It is obvious that the proposed VFMM has very high performances in terms of magnetization characteristic, efficiency, and torque density.