Semi-analytical Homogenized Model of AC Loss in HTS Stacks under External Field

Accurately calculating the AC losses of DC-carrying coils under external fields is essential for assessing the electromagnetic performance of HTS devices. However, due to the significantly non-uniform current density distribution at the stack ends, calculating magnetic AC loss in large-scale superconducting systems remains challenging. In this work, we propose a semi-analytical homogenized modeling method to enhance computational efficiency while improving model accuracy. The proposed method consists of two steps. First, the integral method submodel, containing only superconducting tapes, calculates the current density distribution of the whole stack and defines the parabolic critical boundary function. Second, the coil submodel in COMSOL application introduces a gradient auxiliary function of the parabolic function, allowing effective homogenized division. The results show that the relative accuracy of magnetic AC loss calculation in our proposed model is improved by several times compared to the previous lognormal model. This indicates that the model enables more accurate division of stack models with non-uniform current density distribution, thereby effectively calculating the AC loss in large-scale HTS systems under external magnetic fields.