Stacked Multicell Converter: Sliding Mode Observation of Flying Capacitor Voltages

This paper introduces a new observation strategy of the flying capacitor voltages dedicated to stacked multicell converters (SMC). The proper operation of this particular converter relies on the equal repartition of the voltage constraints over the semiconductors. This objective is achieved providing the capacitor voltages remain constant. The intermediate voltages can be actively controlled so as to ensure this requirement but this procedure necessitates the knowledge of those quantities at each time. It is both difficult and expensive to measure them considering the voltage levels, which motivates the actual research scope. The solution presented in this paper is based on a sliding mode observation of the flying capacitor voltages by means of phase current measurements