A novel single-stage HPF AC/DC converter with integrated buck-boost and flyback converters

This paper proposes a novel single-stage high-power-factor ac/dc converter that is derived from the integration of a buck-boost converter and a flyback converter. Both converters share the same active switch. It results in reduction of component count, leading to low product cost. The buck-boost converter serves as a power-factor corrector (PFC) that is designed to operate at discontinuous-current mode to waveshape the input current to be sinusoidal and in phase with the input-line voltage. An unity power factor and low total current harmonic distortion can be achieved. The flyback converter plays the role of the dc/dc converter that provides an isolated output voltage with very low voltage ripple. Since only one active switch is required, the proposed circuit is with simple control. Besides, it can meet the design goals of high power factor, low voltage ripple and low product cost.