Patent ID: 8559202

Claim:
A power conversion apparatus comprising: a plurality of single-phase inverters having respective inputs and outputs and converting input DC power from respective DC power sources to AC power, the outputs of the single-phase inverters being connected in series, wherein the outputs of the single phase inverters connected in series produce an AC output voltage of the power conversion apparatus, with gradational output voltage control, from a sum of output voltages produced by a combination of the single-phase inverters selected from the plurality of the single-phase inverters, and the respective DC power sources that provide respective DC voltages input to respective single-phase inverters include a first DC power source producing the highest DC voltage of the DC voltages produced by the respective DC power sources, and second DC power sources; and a booster circuit including a switch, wherein the highest DC voltage, produced by the first DC power source, is generated by a third DC power source and is supplied through the booster circuit, and the single-phase inverter that receives the DC voltage produced by the first DC power source produces an output voltage having an output pulse width that is adjusted so that total power fluctuation, due to charging and discharging of respective second DC power sources, via respective single-phase inverters, is reduced.