Design and analysis of nanocrystalline core for low-temperature-rise anode saturable reactor

High-voltage direct current transmission relies critically on the anode saturable reactor (ASR) for thyristor protection. To address the reliability limitation caused by ASR temperature rise, this paper proposes a nanocrystalline core design. Through analysis of soft magnetic materials, nanocrystalline alloy is selected for its low loss and robust mechanical properties. A volt-second compensation principle is applied, increasing the core cross-sectional area by 1.38 times to maintain saturation time, while a 13-segment configuration enhances heat dissipation. Coupled field-circuit and multiphysics simulations confirm that the optimized ASR preserves key electrical characteristics including saturation time and current rise rate, while reducing total loss by 66.6% and average steady-state temperature by 29.9%. The design effectively resolves the thermal bottleneck, enabling high-reliability and low-temperature-rise operation.