模块化多电平逆变器的建模与仿真及电容电压平衡控制

Modeling and simulation of modular multilevel inverters and capacitor voltage balancing control

多电平变换器采用较低容量的功率开关器件实现中高压大容量电网电路,模块化多电平变换器(MMC)作为一种新的变流器结构,具有易于级联拓展、输出电压谐波含量低等优点受到日益广泛的关注。主要通过介绍基于风力发电逆变器的MMC的拓扑结构和工作原理,推导了MMC的数学模型,分析采用了载波移相脉宽调制(CPS-SPWM)方式,对逆变器各子模块的电容电压平衡控制进行改进。并基于Matlab/Simulink软件仿真环境建立了电压型MMC 5电平的仿真模型,利用仿真结果验证模型的可靠性和子模块电容电压的稳定性。

Multilevel converters use low-capacity power switching devices to implement medium-high voltage large-capacity power grid circuits.The modular multilevel converter(MMC)as a new converter structure has been attracting increasing attention because of its advantages of easy cascading expansion and low output voltage harmonic content.The article introduces mainly the topology and working principle of the MMC based on a wind power inverter,deduces the mathematical model of the MMC,and analyzes the carrier phase shifted sinusoidal pulse width modulation(CPS-SPWM)method.The capacitor voltage balance control of each sub-module of the converter is improved.Based on the Matlab/Simulink simulation environment,a voltage-level MMC five-level simulation model is established.The simulation results are used to verify the reliability of the model and the stability of the sub-module capacitor voltage.