Universal bus front end PFC fourth-order buck converter as LED drivers

In this paper, a single stage power factor corrected (PFC) fourth-order dc-dc buck converter, having inductor at the source side, is proposed as a driver for LED lighting application. Converter is designed in accordance with IEC 61000-3-2 standards. Discrete time model of the converter is developed and is used for controller design; validate the stability and time-domain performance. A three-loop power factor correction control strategy is implemented to regulate the output voltage and source current to maintain unity power factor. An additional feed-forward control loop is implemented to eliminate flicker caused due to variation in source voltage. Performance of the proposed PFC LED driver is analyzed for a 24 V, 30 W LED string operating close to unity power factor. The PFC fourth-order buck converter is implemented as a universal bus for 24 V, 20 W to 24 V, 60 W. The presented simulation results are in accordance with the analytic studies made in the paper.