Abstract

High Brightness Light Emitting Diodes (HB LEDs) are likely to be used for general lighting applications due to their high efficiency and longer life. LED technology has rapidly developed in recent years to the point that LEDs can be seriously considered for replacing conventional halogen, incandescent and fluorescent lamps in general illumination including streetlights. Innovative driver circuits optimized with respect to functionality, efficiency, cost, size and reliability are an enabler for the successful introduction of new LED based lighting products. In many offline applications, high power factor, and low harmonics are of primary importance. Single stage power factor pre-regulation technology is preferred in these cost sensitive applications where power factor regulation is mandatory, while adding additional power factor correction controller will surely increase the cost. In this paper a long-life high-power-factor integrated converter able to supply LED lamps is presented. The converter is made up by the integration of a two buck-boost converter, which provides the necessary high input power factor and low Total Harmonic Distortion (THD). Output converter can be operated in Continuous Conduction Mode (CCM) or Discontinuous Conduction Mode (DCM). The analysis of the converter is carried out and a design procedure is proposed. Also, the design is performed so that low capacitances are needed at the output of each semi stage. This allows for the use of long-life film capacitors, thus matching the converter lifetime to that of the LED lamp. An EMI filter was used to avoid high-frequency current circulating through the line. Dimming operation of HB LED is also described. The converter is used to provide power factor correction in streetlight application

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