A new low-stress buck-boost converter for universal-input PPC applications

In converters for power-factor-correction (PFC), universal-input capability (ability to operate from any AC line voltage, world-wide) comes with a heavy price in terms of component stresses and losses, size of components, and restrictions on the output DC voltage. A new two-switch topology is proposed to offer very significant performance improvements over the single-switch buck-boost converters (including flyback, SEPIC, and Cuk topologies) and conventional two-switch buck-boost cascaded converters. The proposed converter has buck-boost conversion characteristic, switch conduction losses comparable to the boost converter, no inrush current problem, and potential for smaller inductor size compared to the boost converter.