Patent ID: 7619907

Claim:
A DC/DC power conversion device comprising: n-stage circuits configured by connecting in series circuits of n (where n is 3 or more) comprised of an inverter circuit for driving, which is configured by connecting in series high voltage sided elements and low voltage sided elements made of semiconductor switching elements and by connecting them between positive terminals and negative terminals of smoothing capacitors, and a rectifier circuit, which is configured by connecting in series high voltage sided elements and low voltage sided elements made of semiconductor switching elements or diodes and by connecting them between positive terminals and negative terminals of smoothing capacitors; a first circuit, corresponding to at least one among the n-stage circuits and configured by connecting in parallel cell circuits of m, where m is an integer of 2 or more, including the high voltage sided elements and the low voltage sided elements connected in series for connection between the positive and the negative terminals of the smoothing capacitors, second circuits corresponding to a plurality of remaining circuits among the n-stage circuits; capacitors for energy transfer connected between middle points of the cell circuits and middle points of the second circuits; and column circuits of m comprised of the cell circuits, the second circuits and the capacitors for energy transfer, and wherein the first circuit is either the inverter circuit for driving or the rectifier circuit, and the second circuit is the remaining one between the inverter circuit for driving and the rectifier circuit; the middle points are contact points of the high voltage sided elements and the low voltage sided elements of the cell circuits and the second circuits; and driving signals for driving the respective column circuits have the same driving cycle T and are out of phase with each other.