Study on Electromagnetic Stress Optimization and its Resistant Structure in Toroidal HTS Magnet Applied in High-Energy Density SMES

We proposed a method by optimizing the cross section of toroidal magnet to `D-type' to maximally reduce the situation of stress concentration. Firstly, the magnetic field distribution of both toroidal and D-shaped toroidal magnet was analyzed and compared based on finite element method (FEM), and a convergence curve of maximal magnetic field act on the winding part was obtained. According to this convergence curve, we reproduced an optimized scheme of the `D-type' toroidal HTS magnet for a 400 MJ grade SMES, and analyzed the distribution of electromagnetic stress including von-mises stress and hoop stress in the winding of the magnet. We then built a reinforcement structure for the `D-type' toroidal HTS magnet and evaluated the influence of the material of reinforcement structure on the inhibition of the stress inside the magnet. Based on these results, we plan to summarized an industrialized scheme on the stress protection of the `D-type' HTS magnet for 400 MJ grade SMES.