Improvement of dynamics for a superconducting magnetic bearing (SMB) system

This paper describes the improvement of dynamics for a passive-type superconducting magnetic bearing (SMB) system. The SMB system is composed of a pair of SMBs with high T/sub c/ (critical temperature) superconductors and a rotor with some permanent magnets. The rotor is passively supported by the SMBs without any control mechanisms. The superconductors of the SMBs were field-cooled in the experiments. After the superconductors were cooled, bearing housings of the SMBs were forced to change in the axial direction. Then, the stiffness change and damping coefficient change resulting from the housing displacements were investigated. From the experimental results, it is found that the static stiffness is related to the dynamic stiffness and that the stiffness and the coefficient change according to the housing displacements. The rotor displacement and the rotation angle near the resonance rotation speeds also change according to the housing displacements. These results show that the stiffness and the damping coefficient of the SMB system can be controlled using these processes.