Characterization and Improvement of Axial and Radial Stiffness of Contactless Thrust Superconducting Magnetic Bearings

Contactless bearings based on both permanent magnets and superconducting magnetic levitation are interesting to avoid all the tribological problems associated with contact at very low temperature. Superconducting magnetic bearings (SMBs) find application in mechanical engineering where lack of contact is a requirement or an advantage. In comparison with active magnetic bearings (AMBs), SMBs solve their inherent instability and require less complex control strategies and electronics. However, one of the current limitations is their low mechanical stiffness. Force densities are considerably lower in SMB than the state-of-art values for AMB. This fact certainly limits their applications. In this chapter, we summarize some key strategies for the improvement of radial and axial stiffness among with a description of some SMB in terms of load capability or force relaxation and discuss their advantages and disadvantages. A set of rules for the mechanical design of high-stiffness thrust superconducting magnetic bearings are proposed and experimentally demonstrated.