An optimized control strategy for the modular multilevel converter based on space vector modulation

Abstract

This paper proposes an optimized control strategy for any modular multilevel converter (MMC), based on a generalized space vector modulation (SVM) method. By fully utilizing the flexibility of the SVM method, i.e., the redundant switching sequences and adjustable duty cycles, this optimized control strategy enables optimal capacitor-voltage and circulating-current control of the MMC. The proposed control strategy can also be implemented with other pulse width modulation methods, e.g., the carrier-based modulation and the nearest-level modulation, though sophisticated selection of the common-mode voltage injection may be required. This paper therefore also demonstrates that for the MMC, the SVM is more flexible than other modulation methods. Typical case studies are given to validate the analysis.