Research the Heavy Rare Earth-Free Motor for Hybrid Vehicle

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Shingo Soma, Honda R&D Co., Ltd.


As heavy rare earth elements occur less than one-tenth as often in ore deposits as light rare earth elements.
Future usage needs to be reduced in light of the 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.
In this study, a new motor was developed using heavy rare-earth-free hot deformed magnets with performance and marketability equal to or higher than those of traction motors equipped in one-motor sport hybrid systems.

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