New Systematic Design Methodology of Modular Multilevel Converters in Rectifier Applications

The Modular Multilevel Converter (MMC) is a highly promising topology for high-voltage and high-power applications. Its key advantages include scalability, the ability to achieve high voltages using low-rated switches, low switching frequency, and reduced harmonic distortion due to its multilevel feature. Selecting the appropriate submodule(SM) capacitance, switching device ratings, arm inductance, and input transformer is crucial for achieving a compact footprint, efficient operation, and cost-effectiveness in hardware implementation. This selection process can be performed through time-intensive iterative simulations or using a one-time simulation with analytical support. While various procedures exist for selecting submodule capacitors and arm inductors, but there are few discussions on systematic selection of components by considering parameter interdependencies. This paper introduces new design methodology for MMC in rectifier applications by refining existing analytical expressions. A new approach for determining submodule capacitance, based on charge fluctuation calculations, is proposed. The theoretical findings are validated through simulations conducted in MATLAB/Simulink®.