Numerical and experimental study of transport AC losses in Bi-2223 stacked conductors

In this paper, a 2D multi-physics electromagnetic-thermal coupling model of Bi-2223 stacked conductors was developed, which combined the H-formulation and heat-conduction module. Using the finite element method (FEM), the transport alternating current (AC) losses in Bi-2223 stacked conductors with five different stacking cases were simulated and analyzed to optimize the stacking structure of the conductors, while ensuring a fixed number of Bi-2223 tapes and copper tapes in the stacked conductors. According to the optimized simulation results, three stacked structures with lower transport AC losses were selected and fabricated into three samples of 500 mm in length. The AC losses with transport current were experimentally measured in three different intervals over the length direction of each sample and at three AC frequencies (30 Hz, 45 Hz, and 60 Hz) by electrical measurement method. By comparing numerical simulation results, experimental measurement data and the AC losses computed with Norris analytical formulation, the 2D multi-physics electromagnetic-thermal coupling model developed in this paper was verified for calculating the transport AC losses of Bi-2223 stacked conductors and optimizing the arrangement of the stacked conductors.