AC Loss Characteristic Analyses of Bifilar Stack Composed of Coated Conductors

Bifilar coil is one of the most significant components for high temperature superconducting (HTS) fault current limiters (FCLs). We studied a bifilar stack composed of two coated conductors (CCs) without ferromagnetic substrate, where upper and lower conductors carry current in opposite directions. Three bifilar stack arrangements were designed, depending on the adjacent CCs facing each other by HTS to substrate side (H-S), HTS to HTS side (H-H), or substrate to substrate side (S-S). Numerical calculations, by means of a B-dependent E-J powerlaw relation and non-uniformity Jc distribution along tape width, were carried out to investigate the effect of stack arrangements mentioned above on AC loss reduction and the dependence of AC loss value on bifilar turn number N.