Experimental Evaluation of Cryogenic Performances of Electronic Components for Signal Isolation in Medium Voltage Power Converters

Operating power converters at cryogenic temperature (<-1530C) can improve efficiency and power density. However, the reliable operation of power converters depends on satisfactory performance of all critical components at cryogenic temperature. While most of the critical components have been studied at cryogenic temperatures, some electronic components necessary for electrical isolation in signal circuits of a medium voltage power converter are yet to be evaluated extensively. This work studies the cryogenic performance of isolated auxiliary power supplies (APS), digital isolators, fiber optics, and isolation amplifiers to identify the well-performing candidates and to investigate the possible reason of failures at cryogenic temperatures. It is observed that some isolated APS with high isolation voltage and isolation amplifiers can work satisfactorily at cryogenic temperatures. The digital isolators are found to be more suitable for cryogenic operation than fiber optic links, even though the latter has better noise immunity.