A charge balancing method for series voltage source feeding multilevel inverters (MLI) based on current allocation control is presented. Unlike those MLIs based on isolated dc sources, the series-connected elements in a voltage source string, such as a battery or supercapacitor stack, cannot be by-passed individually. This brings the problems of source imbalance and limited redundant switching states for current allocation control at high modulation index. In this article, the source balance in the switch-ladder inverter is achieved by allocating the current distribution. Furthermore, the balancing effectiveness is enhanced by a novel configuration combining a switched-capacitor (SC) circuit. The working principle and modulation index limit for the current allocation method is elucidated with a flow diagram and mathematical representation. The feasibility and operation of the proposed method and topology are successfully validated by a simulation study and the experimental results.

中文翻译：

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基于电流分配策略的开关阶梯式逆变器及其开关电容器品种的电压源串平衡技术

提出了一种基于电流分配控制的串联电压源馈电多电平逆变器（MLI）的电荷平衡方法。与基于隔离式直流电源的那些MLI不同，电压源串中的串联连接的元件（例如电池或超级电容器堆栈）不能单独旁路。这带来了源不平衡和在高调制指数下用于电流分配控制的冗余开关状态受限的问题。在本文中，通过分配电流分布来实现梯形逆变器中的电源平衡。此外，通过结合了开关电容器（SC）电路的新颖配置来提高平衡效率。通过流程图和数学表示法阐明了当前分配方法的工作原理和调制指数限制。