Thermal quench modeling of REBCO racetrack coils under conduction cooling at 30 K for aircraft electric propulsion motors

Abstract High-temperature superconducting (HTS) racetrack coils are promising components for lightweight, high-power electric machines due to their exceptional current-carrying capacity. However, self-heating due to AC loss or DC short circuits can cause electro-thermal quench, which poses a significant challenge for the design and reliability of superconducting motors. In this study, we apply a robust computational approach that integrates the Minimum Electro-Magnetic Entropy Production (MEMEP) method for precise electromagnetic calculations with the Finite Difference Method (FDM) for detailed electrothermal analyses. The investigation focuses on the response of an HTS racetrack coil subjected to short-circuit DC voltages ranging from low (1 V) to high values (1000 V) at a cryogenic operating temperature of 30 K. The simulations were conducted under two thermal boundary conditions: complete adiabatic conditions and cooling applied to one side of the coil with the top surface fixed at 30 K. The results reveal distinct current and temperature dynamics when varying the voltage amplitude. At higher voltages, the current exceeds the critical value, causing rapid thermal runaway that damages the superconducting material. In contrast, at lower voltages, the coil presents periodic oscillations in current and temperature, demonstrating a complex interplay of thermal diffusion and electromagnetic stability. This study provides critical insights into the thermal management and fault response of HTS coils for power and magnet applications, particularly in the design of superconducting motors for electric aircraft.