Paper Title
An Improved Phase-Shifted Carrier Modulation for Modular Multilevel Converter to Suppress the Influence of Fluctuation of Capacitor Voltage

A multilevel converter is an improved topology used for high-voltage and high-power applications. Since the cascaded sub modules can generate high-voltage waveforms with excellent harmonic performance at low switching frequencies. Many publications have been presented on the modulation and control of this converter type, some of which are based on phase-shifted carrier modulation. This paper presents an analysis of how the switching frequency affects the capacitor voltages, circulating current and alternating voltage at phase-shifted carrier modulation. It is found that integer multiples of the fundamental frequency should be avoided as they can cause the capacitor voltages to diverge. Suitable switching frequencies are then defined for which the arm and line quantities will be periodic and symmetric in the upper and lower arms. The theoretical results are then validated by the simulations result in matlab/simulink.