Improvement of Luminance Efficiency of Buck-type AC-direct LED Circuit Using Energy Recovery Snubber

Abstract

MasterThis thesis presents a method of improving the luminance efficiency of buck-type AC-direct LED circuit. The proposed method uses a energy recovery snubber, which consists of one inductor, two capacitors, and three diodes, to reduce switching loss. The proposed snubber circuit provides ZCS turn-on and ZVS turn-off for the switch, and reduces reverse-recovery-current of the diodes. To verify the effectiveness of the proposed AC-direct LED circuit, the prototype circuit was built and tested at an input power of 30 W. For the experimental results, the luminance efficiency for an input voltage of AC 220 V was measured as 85.07 lm/Wthis value was 4.73%, higher than that of the conventional buck-type AC-direct LED circuit. In addition, the temperature of switch in the proposed buck-type AC-direct LED circuit was measured as 53.6°Cthis value was 48 °C lower than that of conventional buck-type AC-direct LED circui