An Overview on Passive Magnetic Bearings

Magnetic bearings are an area of interest for high speed applications, such as flywheel energy storage systems, to remove friction losses. Stable levitation cannot be achieved through a static passive magnetic bearing system, as indicated by Earnshaw's Theorem. Solutions using active magnetic bearings have been presented which achieve stable levitation, but induce losses in the current used to actively stabilize one or more degrees of freedom. To overcome these losses while retaining stable operation a fully passive architecture can be created utilizing superconducting magnetic bearings. This paper will review the key passive magnetic and superconducting technologies, their design and optimizations methods for different topologies, and existing work done to combine both into a functional stable system.