Modeling of single-stage converters with high power factor and fast regulation

This paper presents an approach to systematically model single-stage DC/DC converters operated in discontinuous conduction mode (DCM) based on the graft scheme. With the graft scheme, the active switches which are with a common node and operating in unison can be integrated to form a single stage converter (SSC). The small-signal models of the SSC can, therefore, be derived by combining those of its originally separate converters. Using the proposed approach can help yield highly related dynamic models of the converters in a family and, in addition, physical insights between the converters can be readily identified. Moreover, the expressions of the small-signal models for the SSCs operated in DCM can be extended to those in continuous-conduction-mode operation. These have made the proposed modeling method valuable and viable. Experimental measurements have demonstrated that the small-signal model of an SSC derived with the proposed approach is relatively accurate.