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

In this paper, an approach for minimizing stress concentration by optimizing the cross section of a toroidal magnet to D-type is presented. To attempt, the magnetic field distributions of both toroidal and D-shaped toroidal magnets were evaluated and compared using the finite element method (FEM), and a convergence curve of maximal magnetic field effect on the winding part was established. We also reproduced an optimal scheme of the `D-type' toroidal HTS magnet for a 400 MJ grade SMES based on this convergence curve, and evaluated the distribution of electromagnetic stress in the winding of the magnet, including von-mise stress and hoop stress. We next constructed a reinforcement structure for the `D-type' toroidal HTS magnet and investigated the effect of the reinforcement structure material on the suppression of the stress inside the magnet. According these results, an industrialized scheme on the stress inhibition for the D-type HTS magnet for 400 MJ grade SMES was summarized.