Low-energy storage fast-start uninterruptible power supply method
View Patent ↗An uninterruptible power supply system has standby and backup modes and can change to backup mode upon detection of a grid fault. In both modes an alternator rotates at synchronous speed so that backup mode capability is ready. An energy storage unit through a DC-AC inverter remains coupled to the grid in standby mode so that it is charged, ready to supply power when changed to backup mode. In standby mode, first and third clutches are disengaged and engaged, transmitting alternator rotary motion to a flywheel but not therefrom to a heat engine. In backup mode, first and third clutch are engaged and disengaged to permit the alternator, via a second clutch, to overrun the flywheel and allow transmitting of flywheel torque to accelerate the heat engine to starting speed for driving the alternator to supply power to the grid after the engine is at operating speed and coupled to the alternator through a locked second clutch and an engaged third clutch.
1. A method of operating an uninterruptible power supply system comprising a flywheel coupled between a heat engine and an alternator, the method comprising the steps of:
operating the system in a standby mode by maintaining the alternator electrically connected to a power grid in a state of readiness to change to a backup mode; and
operating the system in the backup mode by supplying electrical power to the power grid from an energy storage unit and by using the flywheel to rotate the heat engine of the system up to a speed where the heat engine can be started and accelerated to full operation.
2. The method of claim 1 in which operating the system in the standby mode includes charging the energy storage unit by applying electrical energy to the energy storage unit from power grid.
3. The method of claim 1 wherein operating the system in the standby mode includes applying power to the alternator so as to cause rotation thereof at synchronous speed.
4. The method of claim 3 in which operating the system in the standby mode includes actuating a plurality of motion transmitting mechanisms so as to transmit rotary motion to the flywheel but not to the heat engine.
5. The method of claim 4 in which operating the system in the backup mode includes actuating the plurality of motion transmitting mechanisms so as to permit the alternator to overrun the flywheel and allow transmitting of flywheel torque to accelerate the heat engine to the speed where the heat engine can be started.
6. The method of claim 5 wherein at least one of the plurality of motion transmitting mechanisms operates in a locked mode in which said flywheel can rotate up to the same speed as that of said input shaft of the alternator so as to transmit drive torque from said flywheel to said alternator.