Dynamic Behavior of a Flywheel Rotor System Using Superconductor Bearings

초전도베어링을 이용한 플라이훨 로터의 동특성

Recently, several attempts have been made to apply high Tc superconductor bearings of thrust type to flywheel energy storage system (FESS) throughout the world. Radial type superconductor bearings, however, have never been tried to the real FESS. KEPRI has developed its own radial type bearings and is now currently applying them to a FESS designed by KIMM, for the first time. In this paper preliminary test results of bearing performance and dynamic behavior of the flywheel rotor system mounted on them are presented. The dynamic properties, i.e, stiffness and damping, of the superconductor bearings were experimentally estimated using the static loading test as well as the impact test. The test revealed that stiffness value of the present superconductor bearings is about 67,700N/m and the damping value 29Ns/m. It was also found out that these bearings have some levitation drift problems due to excessive vibrations encountered while passing through the critical speeds. With recommend backup bearings to limit the vibration amplitudes of the rotor it is predicted that the flywheel rotor will show stable operations in the design speed range.