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

TL;DR

This paper models the thermal and electromagnetic behavior of REBCO racetrack coils at 30 K under conduction cooling, revealing how voltage levels influence thermal runaway and oscillations, informing superconducting motor design for aircraft.

Contribution

It introduces an integrated electro-magneto-thermal computational approach combining MEMEP and FDM to analyze HTS coil responses under various voltages and cooling conditions.

Findings

High voltages cause thermal runaway and damage.

Low voltages induce oscillatory current and temperature.

Thermal boundary conditions significantly affect coil stability.

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. Here, we apply an electro-magneto-thermal computational approach that integrates the Minimum Electro-Magnetic Entropy Production (MEMEP) method for electromagnetic modelling with the Finite Difference Method (FDM) for electrothermal analyses. The investigation focuses on the response of an HTS racetrack coil subjected to DC voltages ranging from low (1 V) to high values (1000 V) at operating temperature of 30 K. Computations were conducted under two thermal boundary conditions: complete adiabatic conditions and cooling applied to one side of the coil with the top surface at 30 K. We found that 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 aviation applications, particularly in the design of superconducting motors for electric aircraft.