Efficiency and Loss Analysis of a GaN HEMT based Synchronous Buck Converter at 123 K - 298 K

Cryogenic power electronics has been considered as the next step to improve the power converter's efficiency and power density. Many projects have been conducted to investigate the application of cryogenic power electronics in liquid hydrogen based all electric aircraft. Compared with other types of semiconductors, gallium nitride (GaN) high electron mobility transistor (HEMT) is proved to be more efficient at cryogenic temperature with significant on-state resistance reduction. In this paper, a GaN HEMT based synchronous Buck converter is designed and tested at temperature range of [123 K, 298 K]. In addition, air core magnetic and high flux magnetic core are used for inductor and their performances are evaluated under cryogenic temperature. The experimental results demonstrated that GaN HEMT based power converter is suitable for cryogenic and high power applications. However, the traditional magnetic core material has degraded performance under cryogenic temperature. The experimental results are presented and analyzed.