Profitability of low-temperature power electronics and potential applications

This article presents an investigation of the profitability of cryogenic power electronics at different cooling and ambient temperatures. Thermodynamic fundamentals of low-temperature refrigeration processes are considered and the Carnot efficiencies of state-of-the-art refrigerators are evaluated in order to establish the necessary power loss reduction for energetic profitability of low-temperature to cryogenic power electronic systems down to 77 K. In this context, special attention is paid to two loss contributions in a power electronic system which, based on investigations on active and passive components, show the greatest potential for loss reduction at low temperatures. These are the on-state losses of Si and GaN transistors and the DC winding losses of inductors. The analysis shows that over the entire low temperature range, the loss reduction in a cryogenic converter can hardly compensate for the electrical power required to provide the necessary cooling capacity when cooling against an ambient temperature of 300 K.