Designs and analyses of flywheel energy storage systems using high- Tc superconductor bearings

Abstract

A horizontal axle-type flywheel energy storage system was manufactured using high- T c superconductor bearings. The system running in a vacuum chamber mainly consists of a composite flywheel rotor, superconductor bearings, a motor/generator and its controller. The present system was designed to have an energy storage capacity of 440 W h at its operating speed of 40,000 rpm, which is way above two rigid body mode critical speeds. Rotordynamic analysis was performed on this system. Another flywheel system with vertical axis was conceptualized, which uses a hybrid superconductor bearing set to carry the wheel part load. The models for permanent magnet parts of the bearing set were designed using numerical magnetostatic analysis tool. The vertical magnetic force characteristics of the bearing set were experimentally measured. These results were discussed in regard of application to the flywheel system with a passive hybrid superconductor bearing set.