Switchable power converters for multiple input voltage level power factor correction applications

In this paper, two switchable power converters, integrated SEPIC/boost and flyback/boost, are described, analyzed and designed for power factor correction applications with multiple line input voltages (e.g. 120 Vrms and 277 Vrms). The range-selection switch can configure the converter to boost topology at low line input voltages, and to SEPIC or flyback topology at high line input voltage. As a result, the output DC voltage can be set to an intermediate level for overall power conversion efficiency improvement and system cost reduction. boundary conduction mode (BOM) is considered for both topological configurations for the following benefits, 1) Near resistive input characteristics; 2) Smaller inductor sizes compared with continuous conduction mode (CCM); 3) Lower switch current stress compared with discontinuous conduction mode (DCM); and 4) Simple controller. Analytic and experimental results showed that the component current stresses and losses in the switchable converters are significantly lower than those in conventional SEPIC or flyback converters. It is also shown that it is possible to share the same power stage components and the same control IC in the switchable converters with guaranteed absolute stability.