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High efficiency voltage converter

  • US 5,235,501 A
  • Filed: 07/19/1991
  • Issued: 08/10/1993
  • Est. Priority Date: 07/19/1991
  • Status: Expired due to Term
First Claim
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1. A DC-DC voltage converter comprising:

  • a voltage source;

    inverter means connected to said voltage source, said inverter means including a first, second, third, and fourth switching means;

    transformer means connected to said inverter means, said transformer means including a primary winding and a secondary winding;

    rectifier means connected to the secondary winding of said transformer means for supplying a DC output voltage;

    capacitance means connected to said inverter, said capacitance mans including a second capacitor in parallel across the second switching means and a fourth capacitor in parallel across the fourth switching means; and

    control means for regulating the output voltage, said control means supplying fixed pulse width control signals to the first and third switching means and pulse width modulation control signals to the second and fourth switching means in an operating cycle in which (1) the first and the fourth switching means are turned on while the second and the third switching means remain off, (2) the fourth switching means in turned off such that the voltage rise across the fourth switching means is limited by said capacitor means to facilitate zero voltage switching of the fourth switching means, (3) the fourth capacitor is charged to a voltage greater than the voltage source such that a current through the primary winding is driven to zero, (4) the first switching means is turned off after the current through the primary winding reaches zero to facilitate zero current switching of the first switching means, (5) the second and the third switching means are turned on while the first and the fourth switching means remain off, (6) the second switching means is turned off such that the voltage rise across the second switching means is limited by said capacitor means to facilitate zero voltage switching of the second switching means, (7) the second capacitor is charged to a voltage greater than the voltage source such that the current through the primary winding is driven to zero, and (8) the third switching means is turned off after the current through the primary winding reaches zero to facilitate zero current switching of the third switching means.

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