Current Sharing among Transposed Three-Parallel REBa₂Cu₃O_y Tapes in Single-Phase Armature Coils

To realize a large current capacity in REBa2Cu3Oy superconducting coils, we have proposed a cabling design for the transposed multi-strand parallel conductors. This cabling design is also useful for a superconducting armature coil in a fully superconducting rotating machine system. Very recently, we developed an analytical method based on simple modeling, to roughly calculate the current distributions among the continuous strands in rotating machine conditions. In this manuscript, the current distributions predicted by the analytical method were compared with the measured values. Further, to understand the complex current distribution property for the three-strand parallel conductors, the turn number dependence of the current distribution with various transposition combinations was investigated. The current branches were measured under liquid nitrogen temperature of 77.3 K by Rogowski coils by applying AC transport current. The analytical method described the complex current distribution of the strands well, especially the coil with a large number of turns.