Averaged-Switch Modeling of Fourth-Order PWM DC–DC Converters Considering Conduction Losses in Discontinuous Mode

This manuscript addresses dynamic average-value modeling for fourth-order pulse-width modulation (PWM) DC-DC converters in discontinuous capacitor-voltage mode. Although significant literature is devoted to analysis of the inductor-based switching stage of second-order DC-DC converters in discontinuous current mode, much less has been published regarding the discontinuous voltage mode in the capacitor-based switching stage in fourth-order converters. Accurate average-value models are further complicated by the presence of non-ideality in the switching stage components. This manuscript presents a full-order average-value model for the capacitor-based switching stage, taking into account conduction losses according to the energy conservation principle. The proposed model is validated with a hardware prototype and detailed simulation and is shown to accurately predict large-signal time-domain transients as well as small-signal frequency-domain characteristics.