Patent ID: 7596008

Claim:
A power conversion apparatus comprising: a plurality of single-phase inverters, each single-phase inverter including switching devices, receiving DC power from a respective DC power source and producing AC power at an AC-output side, the AC-output sides of the plurality of single-phase inverters being connected in series, wherein the apparatus produces an output voltage that is a sum of respective output voltages generated by the plurality of single-phase inverters; and a DC-DC converter, wherein first and second DC power sources of the DC power sources supply DC power to first and second single-phase inverters, the first and second single-phase inverters having their AC-output sides connected to each other, of the plurality of single-phase inverters, the first and second DC power sources are connected to each other via the DC-DC converter, and the DC-DC converter supplies power from the first DC power source, having higher DC voltage than the second DC power source, to the second DC power source via the switching devices in the first and second single-phase inverters.