Patent ID: 7939968

Claim:
An uninterruptible power supply for providing power to a load, the uninterruptible power supply comprising: a first input to receive input power from an input power source; an output to provide output power; a bypass input to receive bypass power from a bypass power source, wherein the bypass input is selectively coupled to the output to provide output power from the bypass power source; an input power circuit coupled to the first input, configured to receive power from the input power source, and having a DC output that provides DC power having a first DC voltage level; a back-up power source coupled to the input power circuit to provide DC power having a second DC voltage level in a back-up mode of operation; an inverter circuit having an input coupled to the DC output of the input power circuit and an output coupled to the output of the uninterruptible power supply and configured to provide the output power derived selectively from the input power source and the back-up power source; and a bypass switch coupled between the bypass input and the output of the inverter circuit and controlled to operate in a closed position in a bypass mode of operation to power the load from the bypass power source through the bypass switch in the bypass mode of operation; and wherein the uninterruptible power supply is constructed and arranged in the bypass mode of operation to control the inverter circuit to convert AC power from the bypass power source at the output of the inverter circuit to DC power at the input of the inverter circuit; further comprising a battery charger coupled to the input of the inverter circuit to receive DC power and provide power to charge the back-up power source in the bypass mode of operation; and a power supply separate from the battery charger and coupled to the input of the inverter circuit to receive operating DC power from the inverter and constructed and arranged to provide DC power to components of the uninterruptible power supply in the bypass mode of operation.