A superconducting magnetic bearing flywheel system using a multi-surface levitation concept

Abstract

The main goal of multi-surface levitation concept for a superconducting magnetic bearing flywheel system is to maximize the levitation force by using a more than one permanent magnets (PMs) with a single ring high-temperature superconductor (HTS) bulk material. An analytical model for the radial and axial stiffness of the ring HTS-PM is derived using the frozen image approach. The experimental works were carried out for different polarizations of the permanent magnets, and radial and axial stiffness values are obtained from the force measurements. The rotational test of the flywheel system was also realized for different cases. In the experimental studies, it is observed that the polarization of the PMs changes the radial and axial levitation stiffness and the threesurface levitation case generated the higher stiffness when the magnetization is in an attractive direction. Hence, natural frequencies of the flywheel with larger stiffness are moved to higher frequencies, which are desired in practical applications. The multisurface levitation concept introduced in this chapter is a promising technique to increase levitation forces for certain cooling heights and different configurations of the superconducting magnetic levitation systems. © 2019 Elsevier B.V., All rights reserved.