Performance and Analysis of Modular Multilevel Converter

The Modular Multilevel Converter (MMC) represents an emerging topology with a scalable technology making high voltage and power capability possible. The MMC is built up by identical, but individually controllable sub modules. The Modular Multilevel Converter (MMC) is a new topology for multilevel converters with potential for medium voltage and high voltage applications. Equivalent Circuit models and dynamic models for the MMC that provide a faithful representation of system behavior are quite complex given the large number of energy states and control variables. They are not particularly useful in studying the terminal behavior of the converter and for the development of an intuitive control approach to regulate power transfer. A control scheme with a new sub module capacitor voltage balancing method is also proposed in this paper. Modular multilevel converters, based on cascading of half bridge converter cells, can combine low switching frequency with low harmonic interference. They can be designed for high operating voltages without direct series connection of semiconductor element.