Design optimization of TRIAC-dimmable AC-DC converter in LED lighting

Abstract

A LED lighting system becomes a promising alternative as a substitute of fluorescent and incandescent lights due to high light efficacy and long lifetime. The proposed AC-DC converter implements TRIAC dimming with smooth brightness control. While controlling TRIAC dimming, LED current is regulated by primary side regulation (PSR) to save BOM cost such as LED current sensing circuit and opto-coupler. Compact active damper is also applied to stabilize converter operation during dimmer firing with better efficiency and minimized components. The linear frequency control reduces conduction loss and guarantees DCM operation in the wide range of output voltage, which shows excellent power factor correction in single stage flyback topology. The proposed TRIAC-dimming PSR converter has been experimentally verified in 7W LED lighting system.