A Novel High-Power-Factor AC/DC LED Driver With Dual Flyback Converters

This paper proposes a novel ac/dc light-emitting diode driver. The circuit configuration consists of a low-pass filter, a diode rectifier, and two flyback converters which are interleaved operated with 180° phase shift. Although both flyback converters lose the capability of galvanic isolation in this proposed circuit, the active switch of each converter can achieve zero-voltage switching without needing to use the additional active clamping circuit or snubber circuit. Also, the energy stored in the leakage inductance of the coupled inductor can be either recycled or supplied to the output load, resulting in high circuit efficiency and low product cost. Besides, high power factor and low total current harmonic distortion are obtained by operating the flyback converters in discontinuous current mode. The steady-state analyses of different operation modes and the design criteria for circuit parameters are provided. Finally, a 200-W prototype circuit was implemented. Satisfactory performances are obtained from the experimental results.