Frequency responce function of magnetic bearings using high temperature superconductor

Abstract

High-temperature superconductor Y Ba₂Cu₃O_7-x with strong pinning force has allowed the realization of stable magnetic suspension with no control. Two type superconducting magnetic bearings (SMB) using YBCO and permanent magnet were assembled. There were a radial type and an axial type. Dynamic stiffness of each SMB, while being cooled down under a magnetic field by liquid nitrogen, was measured both in radial and axial directions. As a result, it was found that the spring constants of these SMBs were almost as large as a practically desirable value but their damping coefficients were lower than the practical level. These findings are useful as one of the data bases for development of an optimum SMB design to support the weight of rotors in an axial direction.