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Zero-voltage-transition switching power converters using magnetic feedback

  • US 5,477,131 A
  • Filed: 09/02/1993
  • Issued: 12/19/1995
  • Est. Priority Date: 09/02/1993
  • Status: Expired due to Fees
First Claim
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1. In a switching power converter comprising at least one active power switch and at least one passive power switch wherein said at least one active power switch turns off with substantially zero volts and said at least one passive power switch turns on with near zero voltage, a magnetic feedback circuit for achieving substantially zero voltage turn on of said at least one active power switch and for achieving substantially zero voltage turn off of said at least one passive power switch, said magnetic feedback circuit comprising:

  • i) a first inductor (Lfx) including first and second ends and a second inductor (Lfs) including first and second ends, said first inductor (Lfx) magnetically coupled to said second inductor (Lfs), said first end of said first inductor (Lfx) operatively connected to said switching power converter;

    ii) a capacitor (Cx) operatively connected at one end to said second end of said first inductor (Lfx), and operatively connected at another end to said switching power converter;

    iii) a voltage source (Vx) having first (1) and second (2) rails, said first rail (1) operatively connected to one end of said second inductor (Lfs);

    iv) a third inductor (Lx) operatively connected at one end to another end of said second inductor (Lfs);

    v) an active, uni-directional current switch (Sx) having first (a) and second (b) poles, said first pole (a) operatively connected to another end of said third inductor (Lx) and said second pole (b) operatively connected to said second rail (2);

    wherein an increase in current through said uni-directional current switch necessitates a proportional decrease in current through said at least one passive power switch such that ##EQU8## where isx represents the current through said uni-directional current switch and isp represents the current through said at least one passive power switch;

    and wherein current through said uni-directional current switch increases when said uni-directional current switch is on and said at least one passive power switch is on such that ##EQU9## when said passive power switch is on and wherein current through said uni-directional current switch decreases when said uni-directional current switch is on and said at least one active power switch is on such that ##EQU10## when said active power switch is on.

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