Influence of the internal control approach on capacitor´s voltage ripple in modular multilevel converters

The internal dynamics governing the modular multilevel converter can be described by considering the total capacitor´s voltages of each arm and the circulating currents. In this study, dynamics of the total capacitor voltage of the modular multilevel converter (MMC) is analyzed. Depending on the internal control approach adopted which ensure a symmetrical energy distribution in the arms of the converter, the capacitor´s voltage ripple is evaluated, highlighting effects of both the fundamental and the double frequency. Interestingly, it shows a reduction of the overall requirement of the installed energy. Simulation results are presented to verify the accuracy of the analysis.