A single stage single switch parallel AC/DC converter based on two output boost-flyback converter

A single-stage-single-switch (S4) parallel ac-to-dc converter based on single-switch-two-output (SSTO) boost-flyback converter is presented. This converter remarkably improves the power processing performance. The converter contains two semi-stages. One is the boost-flyback semi-stage that has excellent self-PFC property when operating in DCM even though the boost output is close to the peak value of the line voltage. Moreover, it allows part input power transferred to load directly through the flyback path so the power conversion efficiency is improved. The other one is the forward semi-stage that provides another parallel power flow path and improves the regulation speed. Furthermore, the bulk capacitor voltage is low due to only partial power is processed through it. Hence, the proposed converter is suitable for universal input usage.