Patent ID: 7812575

Claim:
A bidirectional DC-DC converter including a first smoothing capacitor connected in parallel to a first power supply, a second smoothing capacitor connected in parallel to a second power supply, a first switching device, a second switching device, a smoothing reactor, and a control means for repeatedly storing energy in and releasing energy from the smoothing reactor and turning on and off the first and second switching devices so that electric power is transferred and received between the first and second smoothing capacitors, the bidirectional DC-DC converter comprising: a resonant reactor; a storage circuit for storing part of the energy released from the smoothing reactor and/or the resonant reactor in a period in which the smoothing reactor releases the energy it stored; and a third switching device by which part of the energy stored in the storage circuit is released into the resonant reactor; wherein the control means operates to turn the third switching device on and off complementarily to the first switching device when the electric power is supplied to the second power supply from the first power supply, and operates to turn the third switching device on and off complementarily to the second switching device when the electric power is supplied to the first power supply from the second power supply so that an output capacitance of the first and second switching device and/or charges stored in a buffer capacitor connected in parallel to the first and second switching device are drawn immediately before the first and second switching device is turned on using the energy stored in the resonant reactor.