A Single-Stage LED Driver Based on Interleaved Buck–Boost Circuit and LLC Resonant Converter

Abstract

A single-stage LED driver based on an interleaved buck-boost circuit and an LLC resonant converter is proposed. The buck-boost circuit and the LLC resonant converter are integrated by sharing switches, which can decrease the system cost and improve the system efficiency. The input voltage of the buck-boost circuit is half of the rectified voltage, and two buck-boost circuits are formed with the two half-bridge switches and corresponding diodes. The two buck-boost circuits work in interleaved mode and the inductor current is in discontinuous conduction mode, both helping to achieve the power factor (PF) correction. A half-bridge LLC resonant converter is adopted here, and the soft switching characteristic of the LLC resonant converter is not changed by the switch integration. The primary-side switches still work in zero voltage switching (ZVS) mode, and the secondary diodes still work in ZCS mode, which both reduce the switching losses and improve the efficiency of the system. The design process is described in detail this paper, and a 100-W LED street lighting prototype is proposed, with a PF of 0.995, a total harmonic distortion of 5.7%, and an efficiency of 91.6% at full load.