Transient Thermal Analysis and Experimental Study of the Closed-Loop No-Insulation HTS Magnets of Superconducting Maglev

Superconducting maglev is one of the important engineering applications of superconducting magnet technology. Offline time and maintenance time are the key problems for engineering superconducting maglev. To meet the engineering requirements of the second generation (2G) high-temperature superconducting (HTS) magnets, it is necessary to study the cooldown, off-line, and reheating processes of superconducting magnets. Based on COMSOL Multiphysics software, 3D transient thermal simulation of the closed-loop 2G HTS magnets non-insulation was carried out. In the cooldown stage, the latent heat changes and cold conduction processes of phase transformation was obtained; In the off-line stage, the whole process lasted for more than 1.5 hours, which meets the engineering requirements; In the reheating stage, the maintenance time of the superconducting maglev train in engineering application is obtained. According to the simulation results, the closed-loop 2G HTS magnets non-insulation were manufactured, excited to 330 kA, cooled, off-line, and reheated. Dynamic test of the prototype was also carried out. The data obtained from the above experiments are collated and exported, the differences between the actual process and the calculation process are analyzed. The results show that the error between simulation and experimental results of transient thermal analysis of superconducting magnet is less than 15%. The transient analysis method proposed in this paper makes a certain contribution to speeding up the engineering application of the closed-loop 2G HTS magnets non-insulation, provides a platform to better understand the manufacturing process, and provides a tool for further optimizing the structure of magnets.