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Switching dc-to-dc converters

  • US 4,504,896 A
  • Filed: 12/20/1982
  • Issued: 03/12/1985
  • Est. Priority Date: 03/18/1981
  • Status: Expired due to Fees
First Claim
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1. A switching dc-to-dc converter for supplying a substantially continuous flow of output current, comprising:

  • first and second terminals for receiving therebetween the primary dc energy to be converted;

    flyback transformer having a first winding and a second winding to which said first winding is continuously transformer coupled and providing the energy storage inductance needed for sustaining said substantially continuous flow of output current, said first and second windings having respective first and second ends with currents of opposite polarities tending to flow from their first ends responsive to waxing or waning of the strength of the electromagnetic field surrounding them, the first ends of said first and second windings being connected to said first terminal, said first winding having between its first end and a point along said first winding not necessarily its second end the same number of turns as said second winding has between its first and second ends;

    first switch means, which connects during each time interval in a first series of time intervals, the second end of said first winding to said second terminal, for completing a path for input current flow through said winding to cause the waxing of the strength of an electromagnetic field for storing energy to be released by the waning of the strength of said electromagnetic field during a second series of time intervals interleaved with said first series of time intervals, during which second series of time intervals said path is not completed by said first switch means;

    means for recovering flyback current flow during said second series of time intervals from said point along the first winding of said flyback transformer means;

    means for providing, as said substantially continuous flow of output current during both said first and second series of time intervals, a combination of currents essentially consisting of the transformed input current flow induced in said second winding during said first series of time intervals and flyback current flow during said second series of time intervals;

    a third terminal for passing said output current;

    a capacitor connecting between said first and third terminals; and

    within said means for providing a combination of currents,a dc-conductive impedance element having a first end connected to said third terminal and having a second end,second switch means selectively connecting during each of the time intervals in said second series the second end of said d-c conductive impedance element and said point along said first winding, andthird switch means selectively connecting during each of the time intervals in said first series the second ends of said dc-conductive element and said second winding.

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