A direct AC LED driver with high power factor without the use of passive components

Abstract

In this paper, a novel driver for high brightness LED applications that can directly run from AC voltage is presented. Conventional LED drivers for such applications consist of switching-type converters which require passive components like high value inductors and electrolytic capacitors for their operation. The use of such components increases the size and cost of the LED system while decreasing the overall life time. The proposed circuit only needs active devices like MOSFETs and op-amps for power processing. The input current is selectively controlled to follow a sinusoidal waveform to achieve low harmonic distortion and high power factor. A simple start-up circuit is also designed for self-sufficient operation with a more efficient set-up under development. The efficiency of the proposed system is around 82% for a 1.5W converter with 9% total harmonic distortion. Such an implementation is also more suitable for IC design. Both simulation and experimental results have been presented to validate the operation of the proposed set-up.