Effect of contact resistivity difference on steady-state characteristics of multi-pole no-insulation HTS field coils in synchronous motors

Abstract Several superconducting motor designs with a power density exceeding 20 kW kg−1 have been proposed and are under development. However, maintaining the stable operation of superconducting coils in a rotating environment remains a partially unresolved challenge. The no-insulation (NI) high-temperature superconductor (HTS) winding technique, which deliberately removes insulation materials between turns, has emerged as a potential solution for superconducting motors. NI HTS coils have demonstrated current bypassing characteristics, making them stable under external field disturbances and robust against local critical current drops. However, contact resistivity, which largely governs the ‘NI behavior,’ has been reported to fall within a broad range in prior studies, making it challenging to consistently obtain specific values. As a result, understanding and managing contact resistivi…