Adaptive Sliding Mode Observer Design for Switching Power Converters

In this paper, a nonlinear adaptive super-twisting(STW) sliding mode observer is proposed for a three-cell converter. The aim is to reduce the number of sensors in such system by estimating all the capacitor voltages only with the measurement of load current. The gains of super-twisting algorithm are allowed to adapt to ensure the establishment of the sliding mode in the presence of uncertainties with unknown bounds. The hybrid behavior of the converter is also taken into account when designing the observer. The recent concept of Z(TN) – observability is applied to analysis the observability of the switching system in order to obtain the estimation of the voltage across each capacitor. Simulation results show the efficiency and robustness of the proposed observer with respect to load resistance variation.