A single-stage three-level isolated PFC converter

The single-stage forward and flyback derived converter topologies are widely preferred at low power applications. For high dc link voltage applications, research efforts focus on multi-level topologies. This paper proposes a new single-stage three-level (SSTL) isolated ac/dc PFC converter for high dc link voltage low-power applications achieved through an effective integration of ac/dc and dc/dc stages, where all of the switches are effectively shared between two operations. With the proposed converter and switching scheme, input current shaping and output voltage regulation can be achieved simultaneously without introducing additional switches or switching action, through two independent PI controllers. Theoretical analyses are supported with experimental results, achieving 90.8% peak efficiency under low line voltage at 500W/48V.