Development of Gate Drive Configuration for GaN Based Cryogenic Power Electronics Converters

Power electronics converters can offer increased power density and higher efficiencies when operated at cryogenic temperatures (CT, $\le$ 123 K). The increase in efficiency is attributed to reduced conduction losses, whereas higher power density can be achieved by capitalizing upon improved switching performance. Both advantages depend how well a switching device performs at CT. Wideband gap devices, especially GaN devices, have been investigated for better performance in such applications. Despite the improved performance of these devices, GaN-based CT converters have not been developed frequently. Some of the reasons for this include: a) non-availability of CT operable gate drive integrated circuits (ICs) and auxiliary components, and b) the inability of those ICs to handle the increased switching speeds of GaN devices at CT. In this article, the authors propose a gate drive configuration for extreme low temperatures, characterize multiple ICs for gate driving, and present four of them operating at different CTs. A customized auxiliary power supply was also developed and tested at 25 K. To validate their operation, device dynamic characterization was performed at 77 K. Based upon the findings, a three-phase GaN-based converter intended for 77 K operation was designed, and a performance comparison was conducted. The article also presents a detailed flowchart for the design of a complete cryogenic converter.