1992 Volume 112 Issue 9 Pages 877-882
A new uninterruptible power supply (UPS) having a flywheel for a energy storage unit is described. The UPS of the rating of 5(kW) and 100(V) has following characteristics:
(1) Battery less system which makes maintenance free and long life about three times of a battery UPS.
(2) Simple power conversion circuit of a half bridge configuration which can realize good input and output waveforms, high efficiency, small size and light weight.
Inside of the flywheel unit rotating 30, 000rpm is vacuumized to eliminate windage losses by a small vacuum pump. And the flywheel rotor is made no mechanical touch in high speed states to get as long life as 30 years. A electrical main circuit is consisted of a half bridge converter, a symmetrical half bridge inverter, and a inverter/converter to drive the fiywheel induction motor/generator. Charging or discharging control of the mechanical energy is achieved by controlling the slip frequency of the induction machine.
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The transactions of the Institute of Electrical Engineers of Japan.A
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