Coupled-inductor Sepic-type PFC with soft-switching feature for LED lighting applications

In this paper, a coupled-inductor Sepic-type power factor corrector (PFC) with soft-switching is proposed to drive high brightness LED panel. The two inductors in the Sepic-type PFC are magnetically coupled to lower volume. A soft-switching cell composed of an active switch, a resonant inductor and a resonant capacitor is embedded into the PFC to obtain zero-voltage switching (ZVS) feature so as to promote converter efficiency. The proposed PFC is suitable for universal-line input 85Vac ~ 265 Vac for low output voltage applications. Over the input voltage range, it can achieve high efficiency and high power factor. To drive LED panel, a digitalized feedback control loop is adopted to accomplish current sharing, voltage regulating, and dimming feature. A prototype is designed, analyzed and implemented to demonstrate the feasibility of the Sepic-type PFC. Simulation results and hardware measurements have illustrated that the proposed PFC driving LED panel can achieve high power factor, improve efficiency, and accomplish current sharing and dimming feature.