[SIS6] Industrial Application of Functional Materials

[16C-SIS6-01] Special Invited: Development of Technology to Make Smaller and Improve Function of Powder Magnetic Core for Reactor Used in Electric Vehicles

*S. Saigusa¹, M. Suzuki¹, K. Ishii¹, M. Otsubo², T. Hattori², T. Ogawa³, S. Ohira⁴ (1.Toyota Motor Coorporation, Japan, 2.Toyota Central R&D LABS., INC., Japan, 3.Daido Steel Co., Ltd, Japan, 4.Fine Sinter Co., Ltd. Japan)

Keywords:powder magnetic core, Fe-Si-Al, Al2O3 insulating film, reactor, electric vehicles

We have developed Fe-Si-Al powder with Al₂O₃ insulating film and a new powder magnetic core made by molding and annealing this powder for reactor used in electric vehicles. In this magnetic core, the developed Al₂O₃ film on the surface of powder particles performed the magnetic resistance function that conventional gap spacers had, and achieved the targeted linear magnetization curve. This has made the reactor smaller, lowered power loss, and reduced parts. The raw material Fe-Si-Al powder was made low loss by applying gas atomization technology, and the film thickness of Al₂O₃ was made uniform by a new method based on metal vapor phase reaction process. Furthermore, the strength of the core was significantly improved, which was achieved by mixing a small amount of glass powder and molding the core, then melting and hardening the glass during annealing. This product has been adopted from vehicles released on the market in 2022.