Accurate state estimation in DC-DC converters using a Proportional-Integral Observer (PIO)

This paper focuses on state estimation of DC-DC converters in the presences of a biased duty-cycle which is very common in practice. It is shown that the commonly used Proportional (P-) observer fails to estimate the state of the converter when an unknown biased duty-cycle is present. To address this issue, a Proportional-Integral (PI-) observer is proposed, and its design is formulated as a H_∞/L₂ problem. A sufficient condition is derived by using the Lyapunov stability theorem and linear-matrix-inequality (LMI) design tool, guaranteeing the convergence of the observer´s estimation error. The effectiveness and robustness of the proposed technique is verified and is compared with the P-observer observer through an experimental test on a step-down buck converter.