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Study on AC Loss Reduction in HTS Coil for Armature Winding of AC Rotating Machines

The fundamental study on the ac loss reduction in high-temperature superconducting (HTS) coils for armature windings of ac rotational machines is presented in this paper. In this paper, a simplified model that simulates a part of the distributed armature winding of ac rotational machines is used. For the ac loss reduction, we study a method to reduce the perpendicular magnetic field applied to the tape surface in the coil by arranging a magnetic material around the coil winding. The numerical magnetic field calculation shows that the perpendicular magnetic field clearly decreases by arranging the magnetic material around the coil winding in the slot of the iron core. To investigate the effect of the insertion of the magnetic material on the ac loss reduction, we fabricate the measurement setup using the test HTS coils wound by a Bi2223 tape and a YBCO tape, combined with the laminated iron core. The transport ac losses in the test coils are measured by changing the arrangement of the magnetic material. The measurement results demonstrate well the ac loss reduction by use of the magnetic material around the coil winding in the slot of the iron core.