Optimization of the Force and Stiffness in a Superconducting Magnetic Bearing Based on Particular Permanent-Magnet Superconductor Configuration

One of the most challenging issues in superconducting-bearing technology is the rotor's stability, which is closely related to the levitation configuration. Establishing a stable and fixed position of the rotor requires strong stabilizing forces among the bulk superconductor and permanent or electromagnets. The proposed configuration for the superconducting magnetic bearing in this paper consists of a permanent magnet on the rotor and a combination of a cylindrical bulk superconductor and a ring permanent magnet base. The load-carrying capability of the proposed bearing configuration is analyzed in terms of the vertical force on the rotor as a function of the vertical and lateral displacements. In addition, the lateral stability mechanism is evaluated by determining the lateral forces on the rotor as a function of the vertical and lateral displacements. The forces on the rotor are determined with a quick and effective calculation by using MATLAB for various design configurations based on the considerations of the cooling procedure of the superconductors, the Amperian current approximation, and the frozen-image model. According to the results of the analysis, for the same levitation heights the proposed bearing design having ring permanent magnet in the base provides levitation force higher than that of without having the ring permanent magnet. The present levitation configuration provides better clearance between the rotor and stator in the bearing.