A single-stage AC/DC converter for LED street lighting system

A novel single-stage ac/dc converter of high brightness light emitting diode (HB-LED) lighting system for street lighting is proposed. Two boost circuits in discontinuous mode were formed by integrating the switches of the half bridge, and since the two boost circuits work in interleaving mode, the bus voltage can be a little higher than the input voltage, which makes the topology have low voltage and current stress even when the input voltage is high. LLC resonant converter was adopted, so the switches in the primary side can work in zero-voltage-switching mode (ZVS), and the diodes in the secondary side can work in zero-current-switching (ZCS) mode, which decreased the switching loss and improves the efficiency of the system. Through simulation, the converter proposed has power factor correction (PFC) function, and the system can work with soft switching. A 100W prototype was proposed in the laboratory, and experimental results show that with 45%~100% load range, the power factor(PF) is higher than 0.96, the total harmonics distortion(THD) is lower than 10%, and the efficiency is as high as 91.1% in full load.