A Novel Z-Type Modular Multilevel Converter With Capacitor Voltage Self-Balancing for Grid-Tied Applications
Tong Zheng, Congzhe Gao, Xiangdong Liu, Xiaozhong Liao, Jun Liang, Zhen Chen, Baiyan Sun, Jingliang Lv
Abstract
The modular multilevel converter (MMC) has been proven to be an effective solution for grid-tied applications with medium/high voltage ratings. The MMC contains a large amount of floating capacitors, which require the voltage balancing control. The voltage balancing control complexity is normally increased with the number of floating capacitors. As a result, the computation burden of the controller as well as the corresponding hardware cost will be high. This article proposed a novel Z-type MMC, which can achieve capacitor voltage self-balancing without any balancing control. Therefore, the overall control of the converter is significantly simplified. Both mathematical analysis and experimental results have confirmed the effectiveness of the proposed method.