Modulation Considerations for Modular Multilevel Converter Operating with Parallel Branches and Phase-Shifted Carriers

The branch paralleling represents one of the available options with regards to the modular multilevel converter power extension. In such a case, the main technical challenge resides in the control domain, whereas a new set of possibilities from the voltage modulation standpoint becomes available along the way. This paper provides a thorough mathematicalanalysis of the modular multilevel converter operating with parallel branches and utilizing phase-shifted carrier modulation to synthesize the desired voltage references. The influence of the adjacent branches’ carriers shift on the voltages across the terminals of the converter leg is presented in a comprehensive manner. Detailed simulations confirm the derived mathematical predictions and allow for the performance guided choice of relevant modulator parameters.