Coupling loss at the end connections of REBCO stacks: 2D modelling and measurement

In high power density superconducting motors, superconducting tapes are usually stacked and connected together at terminals to improve the current capacity. When a parallel sinusoidal magnetic field is applied on this partially coupled stack, the coupling current is induced and causes additional coupling loss. Usually 3D modeling is needed to calculate the coupling loss but it takes too much computing resource and time. In this paper, a numerical 2D modeling by minimum electromagnetic entropy production (MEMEP) method is developed to speed up the calculation. The presented MEMEP model shows good accuracy and the capability to take the realistic resistance between tapes into account for coupling loss calculation with a high number of mesh element, which agrees to measurements.Thanks to the model, a systemic study of coupling loss on amplitude-dependence, frequency-dependence, resistance-dependence, and length-dependence, is presented and discussed. The results reveal the features of coupling loss which is very helpful devices with multi-tape conductors, such as the stator or rotor windings of motors. (paper)