Journal: Physica C: Superconductivity and its applications
Authors: Y.K. Kwon, H.M. Kim, S.K. Baik, E.Y. Lee, J.D. Lee, Y.C. Kim, S.H. Lee, Jung-Pyo Hong, Y.S. Jo, K.S. Ryu
DOI: 10.1016/j.physc.2010.05.201
High temperature superconducting (HTS) motors electromagnetically consist of a rotator wound with HTS wires and an armature with conventional copper wires like Litz wire. The HTS rotor windings, as field coils, consist of a straight part and an end-ring part. Because a major rotation torque is induced by an interaction between magnetic fields and current-carrying conductors in the straight part, most of mechanical stresses in the motor occur at the straight part. An end-ring is placed in the edge of the straight part and used to connect to each adjacent straight-part coils. The magnetic fields by coil currents concentrate on the end-ring part, therefore, it is expected that the critical current of the entire coil, straight and end-ring, can be determined by the magnitude of the field in the end-ring. This paper deals with the overall Jc degradation in the end-ring part by self-field generated from the coil. In addition to electromagnetic analyses, we have performed a numerical analysis in order to evaluate mechanical stresses in the straight part of field coil by armature reaction on steady-state operation. The analytical results will be presented in this paper.