Sliding mode observer design based linear matrix inequality approach for a Three-Cell Converter

In this paper, a sliding mode observer has been designed to estimate the floating capacitor voltages of the three cell converter. Due to its hybrid behavior, a new concept recently introduced based on geometrical condition is applied to analyze the observability along of a hybrid time trajectory, which leads to a necessary and sufficient condition in term of switching control sequence, under which the capacitor voltages can be reconstructed. The convergence of the observed floating voltages to their references is related to the existence of a solution to a linear matrix inequality. Finally, simulation results are given to illustrate the efficiency of the designed observer.