Modular Multilevel Converter (MMC) is an attractive candidate in high power conversion due to its modularity and scalability. The energy storage element, namely the submodule capacitance in the MMC submodule circuit, is typically large and when scaled to convert high power, requires very bulky submodule capacitors. In addition to deteriorating the power density, the design necessitates the use of electrolytic capacitors further affecting the overall converter efficiency and reliability. This work presents a MMC submodule topology and the accompanying modulation approach that reduces the submodule capacitance requirements significantly compared to conventional MMC topology (few micro-farads versus several milli-farads). The digest summarizes the analytical details of the approach along with a preliminary comparative study. The work is verified using circuit simulations and a laboratory-scale experimental prototype. The final paper will present the analysis and results in extensive detail.
