Design and Validation of a 20-kVA, Fully Cryogenic, Two-Level GaN-Based Current Source Inverter for Full Electric Aircrafts

This article presents the design of a cryogenic power electronics converter using wide bandgap (WBG) devices. A 20-kVA two-level current source inverter (2L-CSI) is designed and validated under both room temperature (RT) and cryogenic temperature (CT) of 77 K. CSI has been neglected because of the physically large and heavy dc-link inductor compared to the dc-link capacitor of voltage source inverters (VSIs). However, higher power, together with operation at CT in fully electric aircrafts (FEAs), makes them superior in size, volume, and power quality. The advantage in volume is primarily attributed to the utilization of air-core inductors with superconducting tapes as dc-link storage elements. Therefore, a 2L-CSI with both power stage and associated components at CT is designed and evaluated. As part of converter development, commercially off-the-shelf (COTS) products, including integrated circuits (ICs), isolated auxiliary power supplies, and passive components, were utilized. Numerous laboratory prototypes of cryogenic subsystems were built to screen out the cryocompatible components. Based on components screening, converter subsystems, namely, the gate driver (GD) board and the double-pulse test (DPT) platform, were also developed. Characterization of these subsystems was performed both at RT and CT, where both individual testing and integrated testing were carried out.