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Electronic ballast having improved power factor and total harmonic distortion

  • US 9,161,422 B2
  • Filed: 03/15/2013
  • Issued: 10/13/2015
  • Est. Priority Date: 11/26/2012
  • Status: Active Grant
First Claim
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1. An electronic ballast comprising:

  • an EMI filter for protecting the AC line from EMI generated by the ballast;

    a bridge rectifier for rectifying the ballast input AC current;

    a DC bus without a traditional electrolytic capacitor having positive and negative rails coupled correspondingly to positive and negative rectifier bridge terminals;

    a Passive Valley Fill Circuit coupled to the DC bus for smoothing the DC bus voltage, said circuit comprising four series charged and parallel discharged capacitors and nine diodes;

    a high frequency DC/AC inverter coupled to the DC bus for powering a gas discharge lamp with high frequency AC current;

    a bypass capacitor coupled to the DC input of the inverter;

    first, second, third, and fourth capacitors each having positive and negative terminals;

    first, second and third charge diodes;

    fourth, fifth, sixth, seventh, eighth and ninth discharge diodes;

    the positive terminal of the first capacitor positive connected to the DC bus positive rail and its negative terminal connected to the anode of the first diode;

    the positive terminal of the second capacitor connected to the cathode of the first diode and the negative terminal of the second capacitor connected to the anode of the second diode;

    the positive terminal of the third capacitor connected to the cathode of the second diode and the negative terminal of the third capacitor connected to the anode of the third diode;

    the positive terminal of the fourth capacitor connected to the cathode of the third diode and the negative terminal of the fourth capacitor connected to DC bus negative rail;

    the cathode of the forth diode connected to the negative terminal of the first capacitor and the anode of the fourth diode connected to the negative rail of the DC bus;

    the cathode of the fifth diode connected to positive rail of the DC bus and the anode of the fourth diode connected to the positive terminal of the second capacitor;

    the cathode of the sixth diode connected to the negative terminal of the second capacitor and the anode of the sixth diode connected to negative rail of the DC bus;

    the anode of the seventh diode connected to the positive terminal of the third capacitor and the cathode of the seventh diode connected to positive rail of the DC bus;

    the anode of the eighth diode connected to the positive terminal of the fourth capacitor and the cathode of the eighth diode connected to positive rail of the DC bus; and

    the anode of the ninth diode connected to the negative rail of the DC bus and the cathode of the ninth diode connected to the negative terminal of the third capacitor.

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