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Quasi-resonant current mode static power conversion method and apparatus

  • US 4,833,584 A
  • Filed: 10/16/1987
  • Issued: 05/23/1989
  • Est. Priority Date: 10/16/1987
  • Status: Expired due to Term
First Claim
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1. Quasi-resonant current mode power conversion apparatus comprising:

  • (a) a resonant circuit having a resonant inductor and a resonant capacitor connected in a parallel configuration with respect to each other;

    (b) a filter capacitor connected in series with the resonant inductor and having substantially greater capacitance than the resonant capacitor, the output voltage across the filter capacitor being the output voltage of the power conversion apparatus;

    (c) a switching circuit including at least two switching devices, which are controllable to be turned on and off, connected together at a node to which the resonant inductor and capacitor are connected;

    (d) control means for switching the switching devices to cause a stable resonant oscillation in the resonant circuit when the switching circuit is provided with a supply voltage such that a high frequency AC resonant voltage oscillation is maintained across the resonant circuit and a lower frequency sinusoidal oscillation is maintained across the filter capacitor, the control means switching the switching devices on and off when the inductor current reaches selected minimum and maximum envelope values such that the average value of the inductor current yields a desired waveform which is at a substantially lower frequency than the frequency of switching of the switching devices.

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