Unified small‐signal model for DC‐DC converters based on the three‐state switching cell operating in discontinuous conduction mode

Abstract

SummaryUnified small‐signal modeling approaches are of paramount importance for the design of controllers and closed‐loop control systems in power electronic converters. In this sense, this work proposes the small‐signal analysis of non‐isolated dc‐dc converters employing the three‐state switching cell (3SSC) in discontinuous conduction mode (DCM). The modeling technique relies on the very same principles of the pulse width modulation (PWM) switch while not involving matrix operations, but only basic concepts related to electric circuits. Considering that the waveforms associated with the terminals of the 3SSC in DCM have a common behavior in all basic dc‐dc converters, it is possible to derive the small‐signal models for both operating regions of the 3SSC, that is, non‐overlapping mode (NOM) and overlapping mode (OM). Thus, one can effectively demonstrate that the same circuit can represent both modes, even though the coefficients that describe the models are calculated from distinct equations. The theoretical claims are validated in the frequency and time domains while comparing the model with the converter. The obtained results evidence that the unified model can accurately represent converters based on the 3SSC in DCM.