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DC-DC converter

  • US 7,333,348 B2
  • Filed: 06/06/2006
  • Issued: 02/19/2008
  • Est. Priority Date: 03/18/2004
  • Status: Active Grant
First Claim
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1. A DC-DC converter comprising:

  • a first voltage resonance circuit including first switching elements which are so connected as to be alternately switched, to which direct-current power is input from a low-voltage direct-current power supply the first voltage resonance circuit converting the direct-current power to an alternative-current power and outputting the alternative-current power;

    a first driver circuit which alternately and selectively turns on and turns off the first switching elements at a zero crossing timing to maintain the first voltage resonance circuit in a resonance mode, wherein substantially no conductive current is supplied to the first switching element and substantially no voltage is applied to the first switching element at the zero cross timing;

    a first insulating high-frequency transformer which has a primary side and a secondary side, the output voltage being applied to the primary side from the first voltage resonance circuit;

    a first current resonance circuit which is connected to the secondary side of the first transformer;

    a first rectifier circuit which rectifies the output current output from the first current resonance circuit;

    a first smoothing circuit which smoothes the output voltage from the first rectifier circuit to output a first output voltage;

    a second voltage resonance circuit including second switching elements which are so connected as to be alternately switched, to which the direct-current power is input from the low-voltage direct-current power supply, the second voltage resonance circuit converting the direct-current power to an alternative-current power and outputting the alternative-current powera second driver circuit which alternately and selectively turns on and turns off the second switching elements at the zero cross timing to maintain the second voltage resonance circuit in a resonance mode, wherein substantially no conductive current is supplied to the first switching element and substantially no voltage is applied to the first switching elements at the zero cross timing;

    a second insulating high-frequency transformer which has a primary side and a secondary side, the output voltage being applied to the primary side from the secondary voltage resonance circuit;

    a second current resonance circuit which is connected to the secondary side of the second transformer;

    a second rectifier circuit which rectifies the output current output from the second current resonance circuit;

    a second smoothing circuit which smoothes the output voltage from the second rectifier circuit to output a second output voltage;

    a pulse-width modulation circuit which pulse-width modulates the first and second output voltages from the first and second smoothing circuits, and comprises a first diode connected between the high potential sides of the first and second output voltages, a second diode connected to the low potential sides of the first and second output voltages, and a third switching element connected between the first and second diodes;

    a third smoothing circuit which smoothes the output voltage from the pulse-width modulation circuit to output a third output voltage; and

    a pulse generator which generates a pulse signal to alternately turn on and turn off the third switching element, the turning on of the third switching element connecting the first and second diodes to the third smoothing circuit in series, and the turning off of the third switching element connecting the first and second diodes to the third smoothing circuit in parallel.

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