Cryogenic DC Circuit Breaker Based on High-Power Press-pack IGBT

The application of cryogenic and superconducting technologies could revolutionise aircraft electric propulsion systems by substantially increasing their power density and energy efficiency. However, designing and selecting components that can operate at cryogenic temperatures present significant challenges. Fault protection in the closely coupled onboard DC power networks of electric aircraft is particularly difficult due to the rapid rise and high magnitude of fault currents. A hybrid DC circuit breaker integrated with a current limiter is a promising solution for fault protection. In this paper, a high-power 3.3 kV/1.5 kA press-pack IGBT has been chosen and investigated as the main breaker of the proposed hybrid DC circuit breaker, with metal oxide varistors (MOVs) to clamp the voltage during current interruption. Modifications to the press-pack IGBT and MOV are introduced to make them compatible for cryogenic operations. The junction temperature rise of the press-pack IGBT during current interruption is then simulated. High-current interruption tests are conducted at both room temperature and cryogenic temperatures. The experimental results demonstrate that the 3.3 kV/1.5 kA press-pack IGBT can interrupt currents exceeding 5.1 kA when immersed in a liquid nitrogen bath. Additionally, the voltage across the DC circuit breaker is clamped below 1 kV using cryogenically compatible MOVs.