Performance of high temperature superconducting field coils for a 100 HP motor

A superconducting motor consisting of high temperature superconducting (HTS) rotor and air-core stator is under development in Korea Electrotechnology Research Institute. HTS motor was designed for having the rated power of 100 HP at 1800 rpm. HTS field winding is composed of sixteen HTS race track shaped coils wound with stainless steel-reinforced Bi-2223 tape conductor by react and wind fabrication method. Nomex paper was used for electrical insulation. Each of four field coil assemblies was constructed with four double pancake sub-coils, mechanically stacked and electrically connected in series. Four field coil assemblies were fixed on an aluminum support structure to make effective heat transfer. Voltage terminals were attached to both ends of joints to measure joint resistances. HTS field winding was tested at 77 K, and the Joule heats generated at a the joints was calculated. In this paper, design, construction and testing of HTS field winding, Joule heat generated by the joints, and operating current were discussed.