Selection of suitable carrier-based PWM method for Modular Multilevel Converter

The Modular Multilevel Converter (M2C) has become the preferred topology for use in high power applications in recent years. This paper gives guiding information for M2C design, in terms of carrier-based PWM methods. Phase and level shift methods are considered. The enhancement due to zero sequence signal injection is also quantified. It is found that output voltage characteristics are highly dependent on the PWM method used. Therefore, selection of the switching method is a critical design issue in M2C studies. Performance evaluation and comparisons are based on Matlab generated switching pulse patterns and the results are validated by computer simulations.