PROJECT TITLE :

Flicker-Free Electrolytic Capacitor-Less Universal Input Offline LED Driver With PFC

ABSTRACT:

Recent developments in improving lighting potency and cost reduction of LEDs have made them appropriate alternatives to the current lighting systems. In this paper, a completely unique offline structure is proposed to drive LEDs. The proposed circuit features a high-input power issue, high efficiency, a protracted lifetime, and it produces no flicker. To extend the lifetime of the converter, the proposed circuit will not embrace any electrolytic capacitors in the power stage. The proposed circuit consists of a transition mode flyback converter in order to improve power factor. Additionally, a buck converter is added to the third winding of the flyback transformer so as to form 2 parallel methods for the electrical power to feed the output load. DC power reaches the load through one stage (flyback) and ac power reaches the load through two stages of conversion (flyback + buck). Thus, within the proposed one-and-a-[*fr1] stage circuit, the potency is improved compared to a regular two-stage circuit. Although the proposed structure has some output current ripple, it is low enough (but 8p.c) that the structure can be rendered flicker free, as shall be mentioned. Principles of operation and design equations are presented furthermore experimental results for a 70zero mA/20 W universal input prototype.