Operation and Performance of Resonant Modular Multilevel Converter With Flexible Step Ratio

Abstract

Resonant modular multilevel converters (RMMCs) have been proposed for high-voltage dc-dc applications. Using different modulation strategies, RMMC operates in different modes and achieves flexible step ratio. To provide a comprehensive study of RMMCs, this paper presents the modulation method achieving a wide range of step ratio with the ability of inherent-balancing. The conditions for guaranteeing the inherent-balancing ability are provided. The operation principle and performance of the RMMC are presented in this paper, which have been explored in a case study. The experimental results are obtained from a bench-scale setup, which have verified the theoretical analysis.