Structure Optimization of a Fully-Superconducting Magnetic Bearing With Hybrid Magnet Stator

With the improvement of the mechanical and electrical properties of superconducting tapes, it will dramatically increase the load capacity of the fully-superconducting bearing employing high temperature superconductor (HTS) coils as a stator and the HTS bulks as rotor. To improve the levitation performance of the fully-superconducting bearing, it is important to maximize the external working magnetic field, and thus, to enhance the interaction with HTS bulk rotor. The emphasis of this article lies in the structure optimization of the fully-superconducting magnetic bearing to improve the levitation performance. A two-dimensional axisymmetric electromagnetic-thermal coupling model was established base on H-formulation in the finite element software COMSOL Multiphysics. Both the magnetic field dependence and temperature dependence of the critical current density were considered to better describe the nonlinear electromagnetic behavior of the HTS material. The relationship between levitation force and working conditions, including operating temperature and suspension height, was investigated. The effects of stator structure and bulk rotor size were studied aiming to increase the levitation force. A new hybrid magnet stator structure was proposed, by which the levitation force was improved by 18.35% compared with the original one. After the adjustment of the bulk size, the levitation force of fully-SMB is further improved by 14.97%.