Single-stage electrolytic capacitor less non-inverting buck-boost PFC based AC-DC ripple free LED driver

This study proposes electrolytic capacitor (EC) less power factor correction (PFC) light emitting diode (LED) driver with reduced current ripple. Generally PFC LED drivers need massive ECs to diminish output current ripple. The life-span of LED driver significantly reduces due to short life-span of ECs, and hence demands for EC-less LED drivers. The proposed LED driver is composed of non-inverting buck-boost PFC converter and bi-directional converter (BDC) for ripple current cancellation which replace the short-life ECs with long-life film capacitors. The PFC converter is designed with discontinuous conduction mode in order to ensure unity power factor operation. The role of BDC is to absorb second harmonic ac ripple current of PFC converter and allow the dc current to LED load. In addition, the desired BDC output voltage (v(cbc)) is higher than the PFC output voltage (V-LED) irrespective of ac source voltage, hence, simplifies the control complexity. Theoretical analysis and predictions of the system have been validated using MATLAB/Simulink simulation, and experimentally validated with a prototype of 7 W. The results evident that PFC integrated BDC provide reduced ripple current with film capacitor as compared with EC counterpart and hence increase the life-span of LED driver.