A single stage single switch valley switching Flyback-Forward converter with regenerative snubber and PFC for LED light source system

摘要

This paper proposes a single-stage single-switch Flyback-Forward converter as a LED driver lighting circuit. The converter is an improvement of a typical flyback converter, when the switch is turned on, the energy can be outputted, when the switch is turned off, also energy can be inputted. The output power is up to 150W-200W. And add a boost inductor in the input of the converter, to make it has the function of power factor correction. In order to improve the efficiency of the converter, design a control loop to make the switch valley switching, to reduce switching losses. And design a transformer leakage inductance energy recovery circuit, when the switch turns off, the surge oscillation can be reduced and the switch voltage is lower than 280V, the leakage inductance energy is stored in the clamp capacitance. At the next switch turn-on, the energy in the clamp capacitor is recovered to the bulk capacitor. Finally, a prototype 150W (36V/4.2A) AC/ DC LED driver and lighting circuits are implemented. The efficiency is above 90%, higher than the efficiency of 85% in the industry.