Investigation of Non-Inductive Bifilar Pancake SFCL Losses in Electric Aircraft Cryogenic Propulsion

Superconducting powertrain is critical for nextgeneration electric aircraft, allowing for lossless power transmission and significantly increasing efficiency, performance, and range. A superconducting fault current limiter (SFCL) is a device on the DC side that uses superconducting materials to control excessive current during faults, thereby protecting the powertrain and enhancing system stability. Among several superconducting fault current limiters (SFCLs), resistive SFCLs (R-SFCLs) have benefits such as compactness, lightweight, high reliability, and a fail-safe nature. When subjected to alternating magnetic fields or currents, superconducting materials exhibit hysteresis, eddy currents, and flux flow effects, which lead to energy dissipation and reduced efficiency. This also applies to RSFCLs operating under normal conditions in the superconducting state, where AC losses occur and require appropriate thermal management to mitigate heat generation and prevent unexpected quenching. DC current ripple and its harmonic contents in an R-SFCL cause additional losses, increasing joule heating and potentially driving the superconductor out of its superconducting state, reducing its efficiency and fault-limiting capability. This research was conducted from two perspectives: theoretical calculations and experiments. The objective is to study the losses in the R-SFCL within the superconducting system, including ripple and harmonic effects, and to determine the design parameters of the R-SFCL cooling system to minimise thermal impacts.