中文摘要：

为研究死区时间对模块化多电平换流器（MMC）的影响,建立了考虑死区时间在内的MMC数学模型并给出了相应的计算公式。首先,在研究换流器运行原理的基础之上,根据阶梯波调制方式,从死区设置方式、桥臂电流方向、子模块状态、桥臂投入模块数及其增加或者减少的方向等方面建立了死区时间对换流器影响的通用数学模型。其次,从基波和偏差角度等方面出发简化了通用数学模型,研究了投入模块数、调制度、负载角度以及死区时间长短对换流器的影响。最后,利用MATLAB/Simulink的矩阵计算和仿真功能对建立的通用数学模型进行了验证。结果表明,死区效应的相对大小分别与子模块数目、死区时间和相位差呈现正相关,与电压调制度呈现负相关。

英文摘要：

In order to figure out the influence of dead time on modular multilevel converter（MMC）, we established a mathematical model of MMC, which took dead time into account, and put forward the corresponding calculation expressions. Firstly, based on converter＇s operation principles, a general mathematical model was developed in aspects of the setting of dead time, arm current direction, sub-module state, and the number and its changing mode of inserted arm modules. Secondly, the general mathematical model was simplified from aspects of fundamental waveform and angle deviation, and the influences of inserted module numbers, modulation degree, load angle and the length of dead time on converter were discussed. Finally, the established general mathematic model was verified through matrix calculation and simulation using MATLAB/simulink. The simulation and calculation results show that the relative size of dead time influence is positively correlated to the number of submodules, dead time, and phase difference, respectively, and negatively correlated to voltage modulation degree.