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US 6,487,092 B2Granted
DC/DC converter
AssigneeFuji Electric Co., Ltd.
InventorYukihiro Nishikawa
Life of this patent
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Abstract
In a DC/DC converter including a half-wave rectifying circuit of a diode and a capacitor for rectifying a voltage occurring on a secondary side of an insulated transformer, an ON period of one of switch elements has a fixed duration, permitting control of an ON period of the other switch element in order to achieve a constant DC output voltage. Since the switching frequency varies only during the ON period of the controlled switch element, an increase in switching frequency is restrained during a period in which the circuit carries light loads.
Claims5
A DC/DC converter for a DC power supply, comprising:
- a series circuit including a first switch element and a second switch element, said series circuit being connected directly between a positive electrode side and a negative electrode side of the DC power supply,
- a transformer having a primary winding connected at one side to a common connection point of the first and second switch elements, and a secondary winding with outputs,
- at least one capacitor connected between a line extending from the primary winding to the common connection point of the first and second switch elements and one of the positive and negative electrode sides of the DC power supply,
- a diode connected in series to the secondary winding, and a smoothing capacitor situated across the secondary winding outside the diode so that the diode and capacitor perform a half-wave rectification, and
- a control circuit connected to the first and second switch elements for switching ON and OFF the first and second switch elements alternately, said control circuit switching ON the second switch element for a predetermined fixed period at all times and changing an ON period of the first switch element so that a DC output voltage from the secondary winding is maintained at a constant voltage.
2 more elements
Dependencies are inferred from the claim text.