A Current-Variation Based Quench Detection Method for Parallel Co-wound Superconducting AC Coils

Magnets wound with superconducting wires, which have high current-carrying capacity, are widely utilized in various applications. In some applications, alternating current (AC) is applied to superconducting magnets, such as in superconducting synchronous electrical machinery and superconducting transformers. Quench detection in superconducting magnets is a critical prerequisite for ensuring their safe operation. However, some conventional quench detection methods commonly used for direct current (DC) superconducting magnets face limitations when applied to those subjected to AC. In this article, we investigate quench-induced current variation characteristics in parallel co-wound superconducting magnets excited with AC current and propose a quench detection method based on current variation. We conducted circuit derivation and artificial quench experiments to validate our approach. Both derivation and experimental results demonstrate that our quench detection method can detect quench with high sensitivity and reliability. This work has potential applications in AC superconducting magnets and may contribute to reducing the risk of quench-induced damage in such systems.