Design Optimization of High Temperature Superconducting Magnets and Null-Flux Coils for Electrodynamic Suspension Train

The introduction of high temperature superconducting (HTS) magnet, which is capable of working at liquid nitrogen temperature, and the use of null-flux coil, make the liquid-helium-free electrodynamic suspension (EDS) train available. In essence, the electromagnetic force of a superconducting EDS train is generated by electromagnetic interaction between the onboard superconducting magnets and the ground null-flux coils. In order to obtain an efficient HTS EDS train, the design optimization of the HTS magnets and null-flux coils is indispensable. This study is devoted to this aspect. We first establish an improved load-line method for efficiently estimating the critical current of HTS magnets and an improved semianalytical model to accurately calculate the induced currents and electromagnetic forces in the EDS train. Based on above two improvements, the onboard HTS magnets and corresponding null-flux coils are then designed and optimized to enhance the overall performances of the HTS EDS train. At final, according to the optimized results, the HTS magnets and null-flux coils were manufactured and measured, followed by the performance analyses of the obtained HTS EDS train. The results have shown that the electromagnetic performances of the designed HTS EDS train are excellent, demonstrating the effectiveness of the optimization methodology.