Cross-coupling effect in hybrid magnet memory motor

Memory motors have been researched extensively in the last decade due to their online magnetization capability. Among many types of designs, the hybrid magnet memory motor (HMMM) has the highest torque density. This presentation investigates the cross-coupling effect of a HMMM in the motor topology proposed by K. Sakai et al. (2009). The analysis model is first introduced. Based on the magnetic circuit model, the mechanism of the open-circuit cross-coupling effect is investigated, while the ideal condition for eliminating this effect is proposed. Later, the on-load cross coupling effect is also analysed by both a magnetic circuit model and 2D FEA focusing on the coercive force (Hc) of the magnet and the interaction between two types of magnets as well as magnetic saturation. Meanwhile, the magnetization characteristics are calculated as well. The results show that increasing Hc of a low-coercive force (LCF) magnet can reduce the cross-coupling effect but increases the difficulty of online magnetization. Therefore, a trade-off exists for choosing a proper LCF magnet in a HMMM.