Patent ID: 8111053

Claim:
A DC-DC converter which increases a voltage of a direct current power supply, the DC-DC converter comprising: a first switch connected to both ends of the direct current power supply via a primary winding of a first transformer; a second switch connected to both ends of the direct current power supply via a primary winding of a second transformer; a first series circuit which is connected to both ends of the first switch and which is formed of an additional winding of the first transformer connected to the primary winding of the first transformer in series, a first reactor, a first diode, and a smoothing capacitor; a second diode connected to a connection point of the primary winding of the first transformer, the additional winding of the first transformer and the first switch, and to one end of the smoothing capacitor; a second series circuit which is connected to both ends of the second switch and which is formed of an additional winding of the second transformer connected to the primary winding of the second transformer in series, a second reactor, a third diode, and the smoothing capacitor; a fourth diode connected to a connection point of the primary winding of the second transformer, the additional winding of the second transformer and the second switch, and to the one end of the smoothing capacitor; a third reactor connected to both ends of a series circuit in which a secondary winding of the first transformer and a secondary winding of the second transformer are connected in series; and a control circuit which alternately turns on the first switch and the second switch every ½ cycle, turns off the first switch during an on-period of the second switch, and turns off the second switch during an on-period of the first switch.