Interleaving Clusters of Submodules to Enhance Scalability of Modular Multilevel Converters for High-Voltage Applications

This article presents a practical architecture for fully exploiting the scalability of modular multilevel converters (MMC) by clustering the submodules (SMs) and interleaving these clusters. The proposed architecture enables scalability and flexibility for various high-voltage applications by dividing the computing tasks of an arm controller among each cluster control iteration, interleaving the output voltages of each cluster to maintain the desired voltage quality without structural changes, and balancing the cluster energy to ensure stable control performance. One noteworthy aspect of the proposed architecture is its implementation of distributed cluster control using a single controller, which eliminates the need for inter-controller synchronization and utilizes hardware resources cost-effectively. The article provides design guidelines for clustering the SMs through theoretical analysis and numerical examples. The validity and performance of the proposed interleaving scheme for the clusters of SMs are demonstrated through hardware-in-the-loop simulation (HILS).