Electromagnetic Modeling of the Copper Layers Influence for AC Losses in ReBCO Coated Conductors Based on T-A Formulation

Abstract

ReBCO coated conductors are a promising solution to be integrated in superconducting electrical machines due to their high transport current under high magnetic fields. However superconducting armature windings will be subjected to AC fields and AC currents, resulting in non-negligible loss. These losses need to be estimated to achieve feasible designs since they strongly decrease the performance of the superconductors, affecting machine operation. In numerical models, ReBCO tapes are often represented by a superconducting thin sheet due to their high aspect ratio. Nonetheless, research shows that at high currents and/or frequencies, the influence of the stabilizing copper layers in the coated conductor's losses can become significant. In this paper, we propose a 2D electromagnetic model based on the T-A formulation to include the effect of copper layers on current distribution and on the evaluation of losses through Finite Elements Method models. A ReBCO tape is investigated when different currents and magnetic fields (perpendicular to the tape surface) are imposed, and the magnetization and transport losses of the superconductors show good agreement with homogenized T-A formulation, experimental and analytical results.