Numerical and Experimental Analysis of AC Loss of YBCO Coated Conductor Carrying DC and AC Offset Transport Current

Because of the complexity of the electrical system, dc offset current and ac ripple current have generally existed. However, they are usually undesirable, and their influence to ac loss is also an important issue for superconducting devices built from YBaCuO-coated conductors. In this paper, ac loss of YBCO tapes with nonmagnetic substrate carrying dc or ac offset current have been both measured and calculated. Experiments based on “electrical method” composed of a high-performance amplifier and a wave recorder with filtering function has been carried out. To verify the measurement, a two-dimensional finite element method model based on finite element method and power law is applied to calculate the ac loss with current combined with ac and dc components. The results show that, a small value of dc offset current in a large ac component has minor effect to the ac loss. In addition, when the total current (combined with ac and dc components) approaches critical value, the ac loss would increase significantly.