Patent ID: 6751107
Filing Date: 2004-06-15
Classification: H02M

Abstract:
A power supply device for supplying an output voltage from a smoothing ciruit to a load, comprising:a first primary winding and a second primary winding, and a first secondary winding and a second secondary winding magnetically coupled respectively to said first and second primary windings; a first current supply circuit and a second current supply ciruit for respectively supplying electric currents to said first and second primary windings and inducing alternating voltages in said first and second secondary windings by making said electric current flow to said first and second primary windings; a rectifying circuit for rectifying the respective alternating voltages induced in said first and second secondary windings and being connected to said first and second secondary winding respectively at their ends, said rectifying circuit having a first rectifying element, a second rectifying element, and a third rectifying element, said rectifying elements being commonly connected to first and second connection points, said first and second connection points being connected to said smoothing circuit; and said smoothing circuit for smoothing the voltage output from said rectifying circuit, other ends of said first and second secondary windings being short circuited, said first and second current supply circuits controlling phases of alternating currents supplied to said first and second primary windings respectively, wherein an operation period of said power supply device includes a period where said first and second secondary windings are connected in parallel relative to said rectifying circuit as a function of polarities of the voltages induced in said first and second secondary windings respectively, and said period of said parallel connection is changed by controlling said phases by means of said first and second current supply circuits.