A Novel Output Current Estimation and Regulation Circuit for Primary Side Controlled High Power Factor Single-Stage Flyback LED Driver

Abstract

A novel output current estimation and regulation circuit for the primary side controlled high power factor (PF) single-stage flyback LED is proposed in this paper. The proposed output current estimation and regulation circuit is composed of a novel output current estimation circuit and a negative feedback networks. The output current estimation circuit can estimate the output current in the primary side and then achieve output current regulation through negative feedback. The proposed output current estimation and regulation circuit is suitable for discontinuous conduction mode (DCM) and boundary conduction mode (BCM). The output of the proposed output current estimation and regulation circuit is a half-sine waveform and followed by the primary current, hence high PF can be achieved. Detailed theoretical analysis and design considerations were presented. Two 340 mA/25 V laboratory LED driver prototypes operating in DCM and BCM were built up. The experimental results verified theoretical analyses.