A generic Lyapunov-based Observer for Double-Star-Chopper-Cell/Bridge-Cell Modular-Multilevel-Cascade-Converters

Modular Multilevel Cascade Converter (MMCC) have achieved a great importance in high voltage converter applications. As they require a high amount of capacitors whose voltages must be known for the control of the MMCC, many voltage sensors are needed. This paper presents a nonlinear Lyapunov-based observer for cell voltage estimation. The proposed observer does solely rely on the knowledge of the phase currents i.e. no voltage sensors are required and the convergence of the estimator is shown with a stability proof by Lyapunov. The performance of the observer is validated simulatively using MATLAB/Simulink.