Design of LED lighting power supply with high power factor based on SEPIC converter

The brightness of LED can be adjusted by traditional LED driver power, but its power factor is very low. In order to solve this problem, SEPIC topology was used to realize PFC and control of LED current according to character of lighting power supply. Traditional SEPIC converter with PFC function worked in DCM (discontinuous current mode). It proved that PFC can be realized by SEPIC with boundary conduction mode(BCM). Through theory analysis and calculation, it was given out that the power factor was high with small value of the ratio of input voltage versus output voltage. Not only controlling the brightness of LED through controlling output current of LED, but also correcting power factor value with single stage circuit which has fewer components and lower power loss can by realized by this circuit. Finally, the theory analysis is proved correct through experiment.