A general approach to averaged modeling and analysis of active-clamped converters

Averaged modeling of soft-switching converters employing active clamping techniques is presented in this paper. A general modeling method based on time-scale separation of converter state variables is used to develop reduced-order large-signal averaged models suitable for converter control design. A transformer-coupled active-clamped SEPIC converter is studied in detail to demonstrate the application of the method. Numerical simulation and experimental measurement of frequency responses of a prototype converter are presented to validate the developed model. An extension to the general time-scale separation technique is also presented as a means to improve the accuracy of the reduced-order averaged model when the switching-frequency ripple in the slow state variables is large. An active-clamped flyback converter is also briefly studied to demonstrate the general applicability of the method to other active-clamped converter topologies