Non-isolated single stage PFC rectifier for wide-input large step-down voltage applications

This paper proposes a non-isolated single-stage high power factor rectifier suitable for applications requiring low-voltage and high-current output. The proposed converter integrates two buck-boost converters with a buck converter. As a result, the proposed converter can operate over a wide range of input voltage with extended low output voltage capability, making it suitable for universal input applications. The proposed topology utilises two synchronised non-floating power switches with low current stress. Additional features are gained when the converter operates in discontinuous conduction mode (DCM). These features include low semiconductors voltage stress, zero-current switch at turn-on, and simple control with a fast well-regulated output voltage and near unity input power factor. Closed form equations of the design constraints for the proposed topology are presented. Simulation and experimental results are presented to demonstrate the feasibility of the proposed technique.

Keywords: AC-DC power conversion, unity power factor, large step-down, universal input voltage, single stage PFC rectifiers, discontinuous conduction mode, power factor correction