Abstract: A flywheel assembly has a base and a flywheel rotatable with respect to and in contact free relation with the base. First and second annular yokes are secured to the base coaxial with the flywheel, and coupled to each other by radially extending control poles. Control coils are wound around the poles. An annular magnet is mounted on the first yoke, coaxial therewith, and a third annular yoke is mounted on the magnet. An outer cylindrical yoke is secured to the flywheel at the outside of the first yoke, and an inner cylindrical yoke is fixed to the flywheel at the inside of the second yoke. The cylindrical yokes are coupled to each other by an annular yoke. A magnetic flux from the magnet flows through the magnet, third yoke, outer cylindrical yoke, first yoke, and the magnet, thereby controlling the axial position of the flywheel.

Abstract: A flywheel apparatus of the invention has a base and a rotor. The rotor is supported by a magnetic bearing. The magnetic bearing has a first annular plate member of a magnetic material, a second annular plate member of magnetic material radially opposing the first annular plate member so as to define a first annular gap, and at least two magnetic circuits formed between the first and second annular plate members as the first annular is a common magnetic path. The apparatus further includes solenoids for changing, at a plurality of positions along the circumferential direction of the first annular magnetic gap, the density of the magnetic fluxes passing along the common magnetic path.