Storage capacitor voltage control of single-stage AC-DC PFC converter

To reduce the storage capacitor voltage stress in single-stage power-factor-corrected (S²PFC) converters due to the change of load, some effective approaches such as variable frequency control and negative bus voltage feedback have been proposed. However, the storage capacitor voltage still varies largely against the change of line voltage. This paper proposes a S²PFC converter with an auxiliary bidirectional switch, operating at zero-voltage-switching (ZVS) condition, to control the storage capacitor voltage. Besides, this switch helps to create a direct power transfer path for efficiency improvement and to reduce the storage capacitor voltage stress at light load condition. A dual-loop voltage mode control is proposed to achieve power factor correction, output voltage regulation and storage capacitor voltage control simultaneously. Simulation and experimental results show that the proposed approach effective.