Effect of Loss Distributions on the Balance of Capacitor Voltages in MMC Using Full Bridge Sub-Modules

2018 4th International Conference on Environmental Science and Material Application

生态环境科学;材料科学

Wang, Chujiao^1 ; Wang, Qin^1 ; Wang, Chuyang^1 ; Chang, Jiajie^1 ; Xiao, Lan^1

School of Nanjing University of Aerona Utics and Astronautics, Nanjing, China^1

关键词: Analytical expressions;    Capacitor voltages;    Loss distribution;    Modular multi-level converters;    Non-ideal conditions;    Output characteristics;    Short-circuit fault;    Working performance;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/252/3/032189/pdf
DOI  :  10.1088/1755-1315/252/3/032189

来源: IOP

【 摘 要 】

With the development of power electronics technology, modular multilevel converter (MMC) has become a popular converter due to its high modularity and good output characteristics. In recent years, half-bridge MMC has been widely studied. Compared with half-bridge MMC, MMC using full bridge sub-modules is more competitive because of its excellent DC short-circuit fault ride-through capability. Furthermore, the balance of capacitor voltages of sub-modules has a crucial influence on the working performance of MMC. To figure out the influence of non-ideal factors on the balance of capacitor voltages, this paper analyses the difference of the capacitor voltages and compares the unbalanced degree of capacitor voltages under different conditions. Firstly, in an ideal situation, the analytical expressions of bridge arm current and capacitor voltage increments are obtained, revealing the dynamic balance process of capacitor voltages. Secondly, expressions in a non-ideal condition reveal the effect of on-resistances of switching devices on the capacitor voltages. Finally, the influence of loss distributions in sub-modules on the balance of the capacitor voltages is analysed theoretically. Simulation models are built in PLECS to verify the theoretical analysis.