Modular Control System with Modular Space Vector Modulation for Modular Multilevel Converter Based on Sub-MMC Concept

Modularity and expandability are among the most important features of modular multilevel converters (MMCs). However, these features are often constrained by the complexity of control systems. In order to leverage the advantages of modularity within the control system, this paper proposes a modular control system for MMCs based on the sub-MMC concept. In this approach, all lower-level control tasks, such as capacitor voltage balancing, differential current control, and modulation, are designed as control module that can be implemented independently for each sub-MMC. Additionally, a modular space vector modulation (SVM) technique is introduced, which can be easily implemented for each sub-MMC. The utilization of the proposed modular SVM method enhances the common DC-link voltage utilization and offers switching state redundancies that can enhance the performance of MMCs. The efficacy of the proposed method is demonstrated by simulation and experimental results.