A Novel Single-Stage AC/DC Converter Integrated Interleaved DCM Boost PFC and LLC DC-DC With Reduced Bus Voltage

Due to the applied pulse frequency modulation control and switch integration, single-stage boost-LLC ac/dc converters suffer from high bus voltage, which makes them difficult to operate for high voltage input. To solve this issue, a novel single-stage ac/dc converter by incorporating the interleaved discontinuous conduction mode (DCM) boost cell and an LLC cell is proposed. Different from the existing topology, in the proposed converter, two capacitors employed for splitting the ac input voltage into two parts are placed before the rectifier bridge. Thus, the voltage across each power factor correction (PFC) cell is halved and the bus voltage can be significantly reduced. Furthermore, two high-frequency diodes and one filter capacitor are omitted, which helps improve the zero-crossing distortion of the input current. More importantly, the circuit efficiency is thus increased. Hence, low bus voltage, low component count, and high efficiency are the main advantages of the proposed converter. Simulations and experimental results are presented to prove the aforementioned features of the proposed converter.