A 0.5 kWh flywheel energy storage system using a high-Tc superconducting magnetic bearing

A flywheel rotor having a main shaft, two flywheel disks and one permanent magnet for a SMB (superconducting magnetic bearing) was designed and manufa ctured. The flywheel was made of CFRP material which is light weight and ha s high tensile strength. The permanent magnet was hooped by CFRP in order t o prevent centrifugal bursting. The rotor was levitated by a SMB in the axi al direction. The radial vibration of the rotor was damped by active magnet ic bearings. The superconducting magnetic bearing was made of YBa2Cu3O7-X w hich had a strong pinning force. The whole rotor system was stably accelera ted up to 30,000 rpm by an induction motor in a vacuum chamber, and then it s energy storage value reached 479 Wh. In this paper, the rotor design, bea ring and rotational properties of the rotor are discussed.