Critical Current and Electric Loss Under Magnetic Field at 30 K on Bi-2223 Superconducting Coil for Ship Propulsion Motor

We are currently under development of a 1 MW-class HTS ship propulsion motor, for which rotating HTS coil made of Bi-2223 tape wire has already been successfully cooled down to 30 K and attained the target performance. There, the electric loss estimation in the HTS tape wire is required under practical operation conditions. The magnetic field angle dependency on I_C-B characteristics of Bi-2223 used for the field winding was measured at 40 K. Furthermore, the interlinkage flux density on HTS coils in the horizontal and vertical directions were calculated using three-dimensional magnetic field simulations. It was found that the estimated electric loss of the entire HTS coil using these measured and simulated results was about 9 W at the operating field current of 200 A, which was considerably small compared with 30 W at 215 A, and that the operating field current of 200 A was appropriate and desirable considering the required refrigerator capacity.