A High PFC AC-DC System For LED Using K Factor Control Driven by Synchronous Semi-Bridgeless Rectifier

Traditional Bridge rectifier incorporates harmonics and distortion to input current shape, considering the advantages and disadvantages of the conventional bridge less rectifier, a modified bridge-less AC-DC converter is proposed to feed a Buck converter supplying a LED load. Traditional bridgeless rectifier involves use of two source inductance and two feedback diodes. In this paper in place of feedback diode we incorporate the use of solid-state switches thus reducing the non-linearity, improving the input power factor as well as the harmonic content in the input current shape. The proposed topology attains standards within IEC61000-3-2 with universal AC mains for LED load. With THD less than 5% and power factor nearly unity a two-stage high PFC LED driver circuit where the second stage is driven by a buck converter is proposed. The proposed topology works in CCM and uses the K controller method which is a modified form of PI controller to attain a desirable phase and gain margin for stability to the second stage buck circuit. The simulation performed using MATLAB/Simulink software. LED load works on constant current for series LED strip and constant voltage mode for parallel strip, the projected two stage LED driver topology simulation results shows regulated output while its input voltage ranges from the 90V-312V peak with low output ripple.