Flicker-Free LED Driver Based on Tapped Inductor Boost-Flyback PFC Converter

A primary side-control LED driving circuit using a tapped boost-flyback power factor correction (PFC) converter is presented, and it is realized by running the input converter under the discontinuous conduction mode (DCM) and the output converter under the boundary conduction mode (BCM). Compared with traditional boost-flyback PFC converter, the intermediate energy storage capacitor voltage stress of proposed converter is decreased remarkably. The LED current of proposed converter can be regulated without secondary side current sensing circuit and opto-coupler by using primary side regulation scheme. As a result, the size and cost of proposed converter can be reduced greatly. The accuracy of the analysis results was tested by conducting experiments using an 18W LED driver.