Current Sharing Among Three-Strand Parallel Conductors Composed of REBCO Tapes in Three-Phase Armature Coil Conditions

Fully superconducting synchronous motors are very interesting for mobile applications such as aviation, thanks to their high output power density (kW/kg). In order to obtain a large current capacity, multi-strand parallel conductors are usually used in armature coils but parallel conductors without transposition present non-uniform current sharing. In this manuscript, current sharing properties among three REBa
₂
Cu
₃
O
_y
parallel tapes with/without a transposition in three-phase armature coil conditions, were investigated experimentally and analytically. The sample coils were prepared under the three-phase arrangement of armature coils for a two-pole rotating machine, and its branch currents were evaluated by Rogowski coils by applying AC transport current in liquid nitrogen at 77 K. We demonstrated that the introduction of the transposition was also an effective way to control the current sharing in rotating magnetic fields generated by the three-phase armature coils as well as single-phase situations. In addition, the influence of other phase armature coils on the current sharing was discussed via analytical calculations.