Analysis on magnetization arrangements of ring-type permanent magnets in four surface levitation superconducting magnetic bearing

Abstract A superconducting magnetic bearing (SMB) composed of a high-temperature superconductor (HTS) and permanent magnets (PMs) is simple and easy in use since it is not necessary to supply a source of electricity for excitation windings. However, the SMB is restricted in the load capacity because of the limitation of the magnetization strength of the PM. Thus, it is a very important problem to improve the load capacity of the SMB. In this paper, we determined a suitable direction of the magnetization of ring-type PMs that brings about the maximum levitation force in the four-surface levitation superconducting magnetic bearing (FSL-SMB) composed of a ring-type HTS bulk and six ring-type PMs. The levitation system, considered in a two-dimensional axisymmetric system, is simulated for the field cooling (FC) state using the H-formulation and the finite-element method. Our simulation results show that the maximum levitation force is generated when only the upper ring-type of PMs is combined with opposite polarity. Also, changing of geometric size of PMs does not strongly influence the suitable magnetization arrangement of PMs for maximum levitation force. The FSL-SMB with opposite polarity provides significantly improved SMBs.