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Currently, electrification for vehicles such as battery electric vehicles (BEV), plug in-hybrid electric vehicles (PHEV), fuel cell electric vehicles (FCEV) and hybrid electric vehicles (HEV) are attracting a great deal of attention, due to the urgent need to reduce CO2 emissions created from transportation and energy dependency on crude oil. Honda has set a target achieving two-thirds of total global sales as electrified by 2030. A traction motor is one of the essential components for electrified vehicles. Generally, Interior Permanent Magnet Synchronous Motors (IPMSMs) are used as traction motors due to their high torque and power density, high efficiency and ease of use. The design of rotors, which consist of magnets and electrical steel sheets, is important for IPMSMs since not only average torque, efficiency and quietness depend on it, but also cost. We have developed a novel rotor, which allows for a degree of freedom in the shape of the magnets.

As heavy rare earth elements are become less prevalent, because one-tenth as often in ore deposits as light rare earth elements. Future usage of need to be reduces heavy rare earth, because of resource risks and costs. As such, a method was developed to recover reductions in coercive force and prevent demagnetization temperature from reducing without adding any heavy rare earth elements. First, a heavy rare-earth-free magnet was developed by hot deformation, which limits growth of crystal grain size, and relationships were clarified between coercive force and optimal deforming temperatures, speed, and total rare earth amounts for heavy rare-earth-free magnets. Second, it was made clear that the permeance coefficient can be increased by reshaping the flux barriers, and that the developed hot deformed magnet can be adopted.