US Patent 7352600 Electric power unit

There is no period of time when any of switching elements and switching elements is turned on in a certain switching frequency, any one switching element is turned on in a period of time except for a dead time period for the zero voltage switching, the switching elements and the switching elements are turned on and off while shifting the phases by 180 degrees, and switching elements are turned on during a period of time when the currents in a positive direction and an inverse direction are flowing to the output, respectively, to be operated in a discontinuous current mode.