Development of Motor with Heavy Rare Earth-Free Magnet for Two-Motor Hybrid System
Published April 2, 2019 by SAE International in United States
Downloadable datasets for this paper availableAnnotation of this paper is available
Conventional HEV motors use neodymium magnets with added heavy rare earths, to realize high output and size reduction. However, deposits of heavy rare earths such as Dysprosium (Dy) and Terbium (Tb) are unevenly distributed, so it is important to reduce the amount used, because of supply issue and material cost. In this paper, the application of a heavy rare earth-free magnet is considered on the new motor for a two-motor hybrid system. Compared to conventional neodymium magnets, heavy rare earth free magnets tend to have low coercivity. Also, heavy rare earth-free magnet have low thermal durability, so it is not easy to apply them to motors for a two-motor hybrid system, which requires high output and small size. The motor requires twice as much torque and six times output than one-motor hybrid system. Increase demagnetization resistance and magnet cooling performance is studied by development of the new motor. With the new rotor structure, a magnetic circuit suitable for the magnetic property of heavy rare earth-free magnet was designed, and demagnetization resistance property is raised 24%. Also, the new motor cooling system is a shaft cooling structure, which uses centrifugal force to supply refrigerant to the interior of the rotor yoke, achieving a 23% increase in magnet cooling performance. This technology succeeded in applying heavy rare earth-free magnet to the motor for a two-motor hybrid system, while maintaining high power density.
CitationIto, Y., Aoki, T., Naito, T., and Hiranishi, T., "Development of Motor with Heavy Rare Earth-Free Magnet for Two-Motor Hybrid System," SAE Technical Paper 2019-01-0600, 2019, https://doi.org/10.4271/2019-01-0600.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
- Higuchi, N., Sunaga, Y., Tanaka, M., and Shimada, H., “Development of a New Two-Motor Plug-In Hybrid System,” SAE Technical Paper 2013-01-1476 2013, doi:10.4271/2013-01-1476.
- Soma, S., Shimizu, H., Shirado, E., and Fujishiro, S., “Magnetic Form of Heavy Rare-Earth Free Motor for Hybrid Electric Vehicle,” SAE Technical Paper 2017-01-1221, 2017, doi:10.4271/2017-01-1221.
- Kuroki, J. and Otsuka, H., “Development of Motor and PCU for a SPORTS HYBRID i-MMD System,” Honda R&D Technical Review 25(2):41-47, 2013.
- Shimizu, H., Kato, R., Nakazawa, Y., Hattori, A. et al., “Heavy Rare Earth-free Hot-deformed Magnet for Traction Motor,” Honda R&D Technical Review 28(2):85-89, 2016.
- Inoue, M., Takamatsu, H., Ogami, M., Ninomiya, K. et al., “New-Structure Motor for Full Hybrid Electric Vehicle,” SAE Technical Paper 2016-01-1225, 2016, doi:10.4271/2016-01-1225.
- Ito, K., Shibata, T., and Kawasaki, T., “Development of New Winding for Compact High-Voltage Drive Motor,” SAE Technical Paper 2016-01-1221, 2016, doi:10.4271/2016-01-1221.
- Ogami, M., Inoue, M., Takamatsu, H., Kamada, T., and Akai, K., “Development of Motor for New Hybrid system,” JSAE Annual Congress 45-16:1100-1105, 2016.