A Novel MMC Sub-module Based on Controllability Theory

作者:Li, Xiangfeng; Zhang, Bo*; Zhang, Zonghua; Qu, Lili; Liao, Hui
来源:43rd Annual Conference of the IEEE-Industrial-Electronics-Society (IECON), Beijing, 2017-10-29 To 2017-11-01.
DOI:10.1109/IECON.2017.8216833

摘要

A novel sub-module circuit is proposed in this paper based on the controllability theory. At first, traditional full bridge sub-modules (FBSM) of the MMC is modeled as a switched linear system, then controllability of the switched linear system model of the sub-module circuit is studied. It is found that the sub-module circuit is state controllable with only four operation modes adopted in the model. Therefore, a novel MMC sub-module circuit is designed to implement the required functionality of the MMC by removing the redundant power semiconductors. At last, the theoretic analysis and simulation results verified that the new MMC with the novel sub-modules is a 3n 1 level converter while the MMC with the traditional FBSM is only a n level converter. Hence the total harmonic distortion (THD) of the proposed MMC topology is much lower than the traditional one. Moreover, since the negative voltage states of the FBSMs are adopted to extend the output voltage range, the maximum output voltage of the MMC topology presented in this paper are increased by two hundred percent such that the dc voltage utilization ratio is improved. More importantly, the approach proposed in this paper can be easily used to redesign and simplify other power converter circuits.