Dimmable Single-stage Sepic-buck Converter for Led Lighting With Reduced Storage Capacitor

Abstract

This paper presents an analysis and design of a Light Emitting Diode (LED) driver aiming to eliminate or 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 longer lifetime capacitor, increasing the overall system life span. 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) operating under discontinuous conduction mode (DCM) because of its 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 106 W LED driver prototype is implemented resulting in 27.1% total harmonic distortion (THD), 50% current ripple on the LED and an efficiency of 92.18%. Furthermore an effective simple dimming strategy is proposed and implemented by an LED parallel active switch.

Keywords

• Electrolytic Capacitor Substitution
• Integrated Converters
• LED Driver
• SEPIC