Development of High Speed Flywheel Rotated in a Vacuum Chamber

Abstract

For the development of high speed flywheel rotation in a vacuum chamber, technology for establishing ultra low loss magnetic bearings and measures for preventing spillover vibration are necessary. For these purposes, tests on two rigs, one involving active magnetic bearings (AMBs) and the other, a medium-size flywheel, were conducted in the present study. With the former, a technique for reducing AMB loss was investigated. In the latter, many trials were carried out in an attempt to find a means for preventing spillover vibration. Based on the results, two important findings were made.First, AMB loss could be reduced to 1/6 of that in conventional control through the use of zero-power control and homo-polar magnetic poles. Secondly, flywheel rotation as high as 12,000 rpm was possible with no significant vibration through phase lead adjustment and the use of a stabilizing filter. Both these possibilities may be attributed to the very precise measurement of natural frequency and the damping ratio.