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High efficiency LED driving method

  • US RE46,502 E1
  • Filed: 01/29/2015
  • Issued: 08/01/2017
  • Est. Priority Date: 05/03/2011
  • Status: Expired due to Fees
First Claim
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1. A driving arrangement for light emitting diode (LED) based luminaire comprising:

  • a driving transformer having a first winding and a second winding, the second winding magnetically coupled to the first winding;

    a switching control circuit;

    a switching bridge comprising a pair of electronically controlled switches coupled to a common node, each of the pair of electronically controlled switches responsive to an output of the switching control circuit, said common node coupled to a first end of the primary winding of the driving transformer;

    a direct current (DC) blocking capacitor coupled between the common node of said switching bridge and a first end of in series with the primary winding of the driving transformer;

    a balancing transformer having a first winding and a second winding, the second winding magnetically coupled to the first winding;

    a first LED string; and

    a second LED string,a first end of each of said first LED string and said second LED string coupled to the second winding of said driving transformer, and arranged to receive electrical energy there from; and

    a second end of said first LED string coupled to a first winding of said balancing transformer, and a second end of said second LED string coupled to a second winding of said balancing transformer,said switching control circuit arranged to provide a switching cycle comprising a first period wherein electrical energy is output from the second winding of said driving transformer with a first polarity, and a second period wherein electrical energy is output from the second winding of said driving transformer with a second polarity, the second polarity opposite the first polarity,said DC blocking capacitor arranged such that the total electrical energy output from the second winding during the first period of the switching cycle is equal to the total electrical energy output from the second winding during the second period of the switching cycle, andsaid balancing transformer arranged such that the current through said first LED string is equal to the current through said second LED string.

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