Hybrid PI&APDR Controller for Current Regulation and Low-Frequency Ripple Rejection in LED Drivers

Abstract

This paper proposes a hybrid dual-loop PI&APDR controller for offline LED drivers where a reduced low-frequency output current ripple and DC regulation is required over a wide operating range. The outer loop employs a PI subsystem designed to maintain the average LED current regulated at the reference value, which depends on the desired output dimming. On the other hand, the APDR subsystem is designed to strictly reject the bus voltage ripple and limit its transmission to the LED current and voltage. Experimental results show the proposed controller feasibility in achieving good tracking behavior, reduced output current ripple, robustness against parametric variations, and simple design and implementation.