Patent ID: 9048753
Filing Date: 2015-06-02
Classification: H02M,Y02B

Abstract:
1. A PFC converter comprising: a rectifying circuit that rectifies an alternating voltage input from a commercial alternating-current power supply and outputs a rectified voltage; a first series circuit that includes a primary winding of a transformer and a first switching element and is connected to an output portion of the rectifying circuit; a filter capacitor connected to the output portion of the rectifying circuit; a rectifying and smoothing circuit that is connected to a secondary winding of the transformer and includes a rectifier diode and a smoothing capacitor; and a second series circuit that includes a second switching element and a capacitor connected in series to each other and is connected in parallel to the filter capacitor, the second switching element conducting in a forward direction when receiving a charging voltage for the filter capacitor; wherein a voltage across the second switching element and the capacitor of the second series circuit is equal or substantially equal to the rectified voltage output by the rectifying circuit; the capacitor of the second series circuit has a capacitance that is several times larger than a capacitance of the filter capacitor; in a complete period in which the first switching element is in an ON state, the second switching element is in an OFF state, and an electrical charge stored in the capacitor of the second series circuit is not discharged, the filter capacitor is arranged such that an electrical charge stored in the filter capacitor is discharged by the primary winding of the transformer and the first switching element; and the filter capacitor is connected to the output portion of the rectifying circuit at a location closer to an input side of the PFC converter than a location of the capacitor of the second series circuit.