Design Methodology of an Electrolytic Capacitorless LED Driver Using SEPIC PFC Converter

Abstract

LED drivers are necessary for LEDs’ operation to control the LED’s current. This current control keeps the LED safe from the thermal runaway caused by the LED’s current increase above the maximum allowable value. The current control is also useful in controlling the output light. So, a reliable LED driver is highly required. The reliability of the LED drivers is strongly affected by the lifetime of the electrolytic capacitor which is small compared to the lifetime of the LED. As a result, in this paper, the electrolytic capacitor is replaced by a longlifetime film capacitor. This replacement is enabled using the SEPIC PFC converter operating in DCM III which enables controllability on the intermediate capacitor voltage. This controllability enables an optimized design for the intermediate capacitor to be a film capacitor and at the same time, the converter achieves an output light flicker within the IEEE Std 1789-2015 for flicker. The detailed design for the converter along with the simulation and experimental results is presented in this paper.