Zero ripple single stage AC-DC LED driver with unity power factor

The single stage LED Driver can achieve relatively high efficiency, however the low frequency ripple current is too significant if high power factor has been achieved. With two stages AC-DC LED Driver structure, we can achieve high power factor and tight current regulation at the same time. However, the drawback of the two stage structure is relatively low efficiency and high component cost. In this paper, an innovative single stage LED Driver with ripple cancellation technology has been proposed. We can achieve almost as high efficiency and low component cost as single stage LED Driver while maintaining comparable performance to the two stages LED Driver. Our experimental prototype can achieve 1.5mA Pk-Pk 120Hz ripple current, 0.99 power factor and 85.5% efficiency for a universal AC input, 35W (50V-0.7A) output application.