A novel coupled analysis method for critical performance of iron-core no-insulation HTS field coils for MW-class wind turbine generator

Conventional models for no-insulation (NI) high-temperature superconducting (HTS) coils have limitations in accurately capturing the bidirectional interaction between iron core saturation and winding current redistribution under rotating generator conditions. This paper proposes a coupled analysis method integrating the partial element equivalent circuit (PEEC) and finite element method (FEM) for iron-core NI HTS magnets in 5 MW wind turbine generators. The core novelty lies in the bidirectional iron core saturation coupling: inductance matrices dependent on both saturation level and rotor position are iteratively updated at each time step to reflect real-time magnetic status, enabling accurate modelling of turn-to-turn current redistribution under both d- and q-axis armature fields. The model is experimentally validated at 77 K and 30 K. At 77 K, the simulated DP inductance and maximum magnetic field agree well with the measured values, with relative errors below 5%. At 30 K, the simulated voltage, inductance and air-gap flux density show good agreement with the measured values, with voltage deviations consistently within 10% throughout the excitation process. This work provides an experimentally validated framework for dynamic performance analysis of NI HTS technology in large-scale HTS wind turbine generators.