Calculating AC Losses in High-temperature Superconducting Cables Comprising Coated Conductors

In this study, we present a new calculation model of AC loss in a high-temperature superconducting (HTS) cable comprising coated conductors. AC loss is calculated by an electric circuit (EC) model. A previous EC model had three circuit elements: resistance as a function of the layer current, inductances related to the circumferential and axial fields. The new EC model has only inductances, and resistance is eliminated. In both models, AC loss of the coated conductor in each layer of an HTS cable is calculated on the basis of the Norris equation for a thin strip. The differences between measurement and calculations using the previous and new models are 12% and 14%, respectively, when transporting 1 kArms, which indicates that the new model is applicable for the calculation of AC loss in an HTS cable. These results indicate that layer current is dependent on inductances and not on resistance. The elimination of resistance simplifies AC loss calculation because it does not require repeated calculations for the convergence of the layer current. The calculation time was 1/20th of that of the previous model. In the new model, the Norris equation can be replaced with the calculation result obtained by the two-dimensional finite element method to obtain more accurate AC loss.