Control of Switched-Capacitor Based Fifth-order Buck-Boost Converter

A fifth-order switched-capacitor based buck-boost converter is proposed in this article. Presence of switched-capacitor provides a wider duty ratio range for bucking operation in addition to boosting feature at higher duty ratios. Principle of operation is explained first, followed by steady-state performance analysis using the time-domain analysis. Using the capacitor and inductor voltage equations, the expressions for ripple currents/voltage are formulated. A brief comparison of other existing buck-boost topologies is presented to bring out the salient performance features of the proposed converter topology. Voltage buck-boost features are demonstrated first in simulation and then later in the experiment. A 30 ~ 50 Watt 50 kHz prototype topology is constructed for experimental studies. Sample experimental measurements are presented for concept validation. They are found to be in line with theoretical derivations.