中文摘要：

提出了以减少多电平变换器中箝位器件的数量为目的的拓扑生成原则，并基于该原则，研究了适用于中压场合的2类新型多电平拓扑。其中一类是通过组合传统的二极管箝位型或飞跨电容型拓扑与两电平桥臂得到的组合型拓扑；另一类是飞跨电容型拓扑的新型组合策略，它考虑了开关管数量和电容电压平衡之间的折衷。这2类新型拓扑都能以较少的器件输出较多的电平数，因此提高了系统可靠性，降低了成本。但是这2类拓扑的缺点是，某些器件需要承受大于1倍的单个电平电压，所以它们更适合于中压高性能的应用场合。仿真和实验结果验证了新型拓扑的有效性。

英文摘要：

To decrease the number of clamping devices in multilevel converters, a topology construction principle was proposed. Based on this principle, two novel types of multilevel converter topologies for medium voltage applications were researched. One was the combined multilevel converter topologies which were constructed by combining the conventional diode clamped or flying capacitor multilevel converters with two-level bridge legs; the other was a novel combination method for flying capacitor converters, which considered a tradeoff between the switching device number and capacitor voltage balancing. Both of the two types of multilevel converter topologies can produce more voltage levels with fewer switching devices. The reliability is improved and costs are saved. But some of the devices will block more than one DC-Bus capacitor voltages. So they are suitable for medium-voltage and high-performance requirement applications. The validity of the novel topologies is proven by simulated and experimental results.