Patent ID: 8536734

Claim:
An apparatus for inverting DC voltage to AC voltage by stacking of DC voltage sources from a series of DC voltage sources, the apparatus comprising: a plurality of power switches including first power switches, second power switches, and third power switches, wherein (i) the first power switches are arranged to allow selective connection of adjacent DC voltage sources in the series to provide stacking of DC voltage sources, (ii) each second power switch is arranged to allow selective connection of a first bus to a corresponding location between adjacent DC voltage sources, and (iii) each third power switch is arranged to allow selective connection of a second bus to a corresponding location between adjacent DC voltage sources; and a controller operative to control the plurality of power switches to produce an AC voltage output by coordinating stacking of DC voltage sources and associated connections to the first bus and the second bus, wherein coordinating the stacking of DC voltage sources includes: coordinating a sequence of steps where DC voltage sources are incrementally connected in series and incrementally removed from the series connection; and continuously repeating the sequence of steps while changing a first DC voltage source in the series connection.