功率 LED 替代灯的新颖谐振式 Buck 镇流器

LEDs are potential successors of incandescent lamps with high luminous efficacy and long lifetime. To improve the overall luminair efficacy and lifetime, the power efficiency and lifetime of LED ballasts become important factors. Efficiency gain in transformer-less power converters appears attractive for applications without isolation. Driving solid-state LED bulbs in an existing lighting fixture from universal mains necessitates a high voltage step-down ratio in order to produce a relatively low output voltage suitable for LED lighting applications. Traditional non-isolated step-down Buck converters may suffer from poor efficiency due to the long diode freewheeling time at small duty cycles. In this paper, a resonance assisted Buck converter is proposed to achieve a high voltage step-down ratio and high converter efficiency, whilst maintaining durability and compatibility with existing incandescent dimmers. The performance of the proposed LED driver is verified experimentally.