AC Losses Analysis on a Twisted Stacked-Tape Cable With Stepped Grooves

Abstract

This article mainly shares an ac loss numerical study of a stacked Yttrium Barium Copper Oxide (YBCO) cable with stepped grooves in 77 K. The model divided YBCO tapes to three layers to balance the accuracy and efficiency. AC loss contributions and Eddy current losses are estimated in detail at various magnetic fields and frequencies. A conventional configuration of TSTC is researched for comparison. With the same number of tapes, the stepped-slot structure is less affected by the magnetic field, resulting in a higher critical current and a lower ac loss compared to the traditional structure. When the current frequency is varied, the stepped-slot structure cable also exhibits lower ac losses. The ac losses in the superconducting layer are greater than the Eddy current losses, which is in contrast to the traditional structure where the Eddy current losses far exceeds the ac losses. As for the study on tape configuration, a more balanced distribution of tapes between the two slots in the stepped-slot structure leads to a reduction in both the external field and frequency dependence, thereby improving the ac losses performance.