Development of the Flywheel for Uninterruptible Power Supply(Mechanical Systems)

A new flywheel Uninterruptible Power Supply (UPS) capable of providing 200kW electric power within 20 seconds have been produced using small homo-polar magnetic bearings with zeropower control which is essentially the same control as previously reported. This flywheel rotated in a vacuum chamber is made of Carbon Fiber Reinforced Plastics (CFRP). It is important to maintain eddy current loss at low level, because rotor temperature rise causes deterioration of strength of CFRP. In this study relationship between rotor temperature and calorific value by the eddy current loss has been predicted and it has had a good agreement with the experimental results. Further the vibration characteristics of the flywheel UPS has been investigated by analysis and experiment. Consequently a loss as low as 16W at a speed of 13000min^ has been achieved. Operation for as long as 1000 hours is possible with no significant rise in temperature.