Dense and Efficient Cryogenic Power Converter Using Stress Annealed and Stacked Nanocrystalline Cores

Cryogenically cooled superconducting motors are capable of electrifying commercial aviation. Using the same cooling system, cryogenic power electronics can provide improvements in density and efficiency. This article proposes a novel cryogenic inductor design that can be used as a filter inductor for a cryogenic inverter. It is found that stress annealed nanocrystalline holds the best properties at cryogenic temperatures, and stacking toroids can help to reduce eddy current losses. The proposed inductor design is used in a cryogenic buck converter and the peak efficiency is 99.3% at 3 kW. The cryogenically cooled inductor design is 2% of both the weight and volume of a similar room temperature ferrite inductor while maintaining the same losses.