Dynamic resistance of REBCO coated conductors (CCs) is one of the key parameters in some high-temperature superconductor (HTS) applications, such as field-triggered persistent current switches (PCS), flux pumps, fault current limiters (FCL), and rapid cycling synchrotrons (RCS). In these applications, REBCO CCs carry DC currents under AC and DC bias fields.

In this work, dynamic resistance in a REBCO bifilar stack has been studied at 77 K when carrying DC currents under combined AC and DC bias fields. The bifilar stack is assembled from two serial-connected REBCO coated conductors, cut from 2 – mm wide SuNAM wire. The transport DC currents vary from 10 A to 40 A with amplitudes of AC magnetic fields up to 350 mT and DC bias fields up to 300 mT. The frequency of AC magnetic fields ranges from 10 Hz to 50 Hz. The influences of these parameters on the dynamic resistance have been studied via experiments and coupled electromagnetic-thermal simulations using 2D H-formulation.

Our results show dynamic resistance of the bifilar stack increases with increasing DC bias fields, which we attribute to degradation of the critical current in the stack caused by the DC bias fields.

Keywords: Dynamic resistance, REBCO bifilar stack, REBCO coated conductors