Buck-Boost Converter Small Signal Model: Dynamic Analysis under System Uncertainties

An accurate mathematical model of DC-DC converters is an imperative for high performance in all domains of electronic systems operations. In this work, a small signal circuit model for DC-DC buck-boost converter operated in continuous conduction mode (CCM) is developed. The proposed modeling is initialized from dynamic equations illustrating the converter. The nonlinear behaviour of the pulse-width modulation and switching process are addressed via the application of waveform averaging and small-signal modeling techniques. A complete MATLAB/Simulink model is designed to check the robustness of the proposed converter under different input voltage and switched load variations. Simulation results present the superiority of proposed model in terms of transient and steady-state performance, such as small overshoot and short settling time. Furthermore, the proposed model can be useful to achieve input and output impedances, inductor current variations, and converter transfer functions to develop a robust closed-loop controller design that can meet stability and performance conditions of the DC-DC buck-boost converter.