Abstract

The intrinsically stable levitation force in superconducting magnetic bearings (SMBs) makes them an appealing technology for transportation industry and in particular maglev vehicles. SMBs made of stacks of HTS tapes possess some practical features to compete with the superconducting bulks by offering better mechanical properties, better heat conductivity and simpler production process. Modeling can be employed as a powerful, cost-effective and fast tool for understanding the physical mechanisms, interpretation of experimental results, and predicting and improving the performance of SMBs. Although several 2D models have been proposed and verified against experiments in the past, there is a lack of stable and fast 3D models for analyzing the performance of SMBs. We developed an open-source software coded in C++ to analyze the performance of a stack-type SMB, and verified our modeling results through comparison with measurements in field cooling and zero field cooling modes at different temperatures, from 77 K to 59 K. Contrary to previously presented models, we used the J_c(B,θ) measurement data to describe the characteristics of the HTS tapes in the stacks. This eliminates the need of artificially calibrating the model against the maximum levitation force to obtain the force-distance hysteresis graph. However, this requires some considerations in using J_c(B,θ) measurement data and implementing it into the model. We have realized that for obtaining good agreement with measurements, it is essential to consider in the model non-uniformity of the critical current density along the tape width.