Characterization of Inductor Magnetic Cores for Cryogenic Applications

This paper presents the magnetic core characteristics of three magnetic materials at cryogenic temperature. Amorphous, nanocrystalline, and ferrite ring cores are tested at room temperature as well as 77 K under various operating frequencies. The core characteristics, including saturation flux density, permeability, and power loss are analyzed. The results show the core characteristic differences between the room and cryogenic temperatures as well as the performance differences among different magnetic materials, which will help optimize the high-frequency inductor design for cryogenic applications. Furthermore, the thermal shock test is performed to test the reliability of the cores. One ferrite core inductor and one nanocrystalline core inductor are built and tested in a 9 kW buck converter at cryogenic temperature.