Controller Design for Buck–Boost Converter Using State-Space Analysis

Abstract

In this paper, the small-signal model of buck–boost DC–DC Converter is presented. The final model is obtained in terms of state matrix (A ), input matrix (B ), output matrix (C ) and feedforward matrix (D ). The small-signal modelling for buck–boost converter is done in order to construct a robust controller for it by using state-space analysis and root-locus technique. The entire system is analyzed by giving a step-input to the system, which is modelled in Laplace domain. This paper primarily focuses on reduction of steady-state error for the dynamic model of buck–boost converter. The controller, comprising of lag compensator, is designed with the help of root-locus technique according to the need of the designed parameters such as settling time, peak overshoot, steady-state error, relative stability, etc. By taking various values of zeros and poles of compensator, the unit step response is analyzed in detail. The presented system also has an inherent characteristic of inverse time response generally exhibited by non-minimum phase system.