A Cryogenically Cooled GaN Buck Converter in a Vacuum

High Temperature Superconducting (HTS) motors have the potential to enable the electrification of large scale transport, including freight, aviation, and shipping. It has been shown in previous work that cryogenically cooled power electronics used in conjuction with an HTS motor may further boost the power density and efficiency of the powertrain. However, all known cryogenic characterisations of GaN based power electronic converters to date have not gone below 77 K, apart from single device characterisations and converters using Si MOSFETs. In this paper the performance of a GaN based buck converter is measured at cryogenic temperatures while attached to a coldhead which operates at 40 K. The results show that the GaN based converter under test is robust and can operate under a wide range of conditions, which is critical for future applications involving HTS motors.