A Novel LED Driver Based on Single-stage LLC Resonant Converter

Inhalt:
In this paper, a single-stage LED driver based on buck-boost circuit and LLC resonant converter is proposed. Two buck-boost circuits are integrated by sharing the switches of a half-bridge LLC resonant converter. Therefore, the system has a low cost and high efficiency. The divided input voltage, two half-bridge switches and corresponding diodes forms two buck-boost circuits, both of which operate in the discontinuous conduction mode (DCM), realizing a power-factor correction function. The soft-switching characteristics of the halfbridge LLC, resonant circuit are not affected by the integration of the switches, with secondary side diodes operating in zero-current-switching(ZCS)state, thus reducing the switching losses and improving the efficiency. A 100-W prototype was developed, and the experimental results prove the rightness of the analysis.