US Patent 7432615 Uninterruptable power supply system and method

Methods and apparatus for delivering uninterruptible power to loads are provided. One aspect on the invention is directed to a system for providing power to a load. The system includes a first input to receive AC power from a first AC power source, a second input to receive AC power from a second AC power source, a third input to receive DC power from a first DC power source, an output that provides output AC power to the load, and converter circuitry, coupled to the first, second and third inputs, adapted to provide the output power derived from at least one of the first AC power source, the second AC power source and the first DC power source.