Patent ID: 6400591
Filing Date: 2002-06-04
Classification: H02J,H02M,Y02B

Abstract:
An uninterruptible power supply for providing AC power to a load having a capacitive element, the uninterruptible power supply comprising:an input to receive AC power from an AC power source; an output that provides AC power; a DC voltage source that provides DC power, the DC voltage source having an energy storage device; an inverter operatively coupled to the DC voltage source to receive DC power and to provide AC power, the inverter including: first and second output nodes to provide AC power to the load having the capacitive element; first and second input nodes to receive DC power from the DC voltage source; a resonant element having a first terminal and a second terminal, the second terminal being electrically coupled to the first output node; a first switch electrically coupled between the first terminal of the resonant element and the first input node, wherein during a first time period, the first switch is selected to enable an electrical current path from the resonant element to the capacitive element, an electrical current of the path storing energy in the resonant element and charging the capacitive element to a first voltage level, and during a second time period, the first switch is selected to block the electrical current path to cause the stored energy in the resonant element to further charge the capacitive element to a second voltage level during the second time period; a set of switches operatively coupled between the first and second output nodes and the first and second input nodes and controlled to generate AC power from the DC power; and a transfer switch constructed and arranged to select one of the AC power source and the DC voltage source as an output power source for the uninterruptible power supply.