A Family of Single-Phase Hybrid Step-Down PFC Converters

Buck power factor correction (PFC) has attracted a lot of research interests for its low output voltage and high efficiency at low input condition. However, the traditional Buck PFC converter usually has low power factor (PF) and poor harmonic performance due to the inherent dead angle of the input current, especially at low input condition. To solve this problem, this paper proposes a family of hybrid PFC converter topologies combining the advantages of step-up PFC and step-down (Buck) PFC converters, which features low output voltage and continuous input current (high PF). The derivation methodology is presented in detail and two topologies are selected as typical examples to explore their performances. With the improved peak current control scheme, the two proposed converters can achieve high PF under universal input range, and their input current harmonics can easily meet the IEC61000-3-2 Class C limits. The optimal design considerations are presented and two 150-W prototypes are built to verify the theoretical analysis.