Single-stage SEPIC-Buck converter for LED lighting with reduced storage capacitor

This paper presents an analysis and design of a Light Emitting Diode (LED) driver aiming to eliminate/substitute the electrolytic capacitors. Considering the low lifetime of electrolytic capacitors compared to LEDs, this topology aims for reducing the storage capacitance and replaces it by a film capacitor, increasing the system lifetime. This reduction is based on designing of the control dynamic with a compromise between the input current distortion and the output current ripple. The power factor correction (PFC) stage is based on a Single Ended Primary Inductance Converter (SEPIC) because of its intrinsic low input current distortion characteristic making it possible to eliminate the electromagnetic interference (EMI) filter. The power control (PC) stage is performed by a Buck converter using its output current source behavior, suitable for LED application. A 100 W LED driver prototype is implemented resulting in a 6.9% total harmonic distortion (THD) and 30% current ripple on the LED.