含开关电容的有源箝位多电平逆变器

Active Clamped Multilevel Inverter With Switched Capacitors

针对传统多电平逆变器输出电平不易扩展的问题,结合开关电容能输出二倍电容电压的特点,提出一种含开关电容的有源箝位多电平拓扑。该拓扑能明显增加输出电平数,由开关电容带来的冗余状态也有利于电容电压均衡,且所含电容少逆变器体积小,适用于低压高功率密度的场合。分析了新拓扑中基本单元分别为开关电容单元和飞跨电容单元的情况,从电容容值和成本角度出发,得出了含开关电容的有源箝位型多电平拓扑构成原则。在此基础上从开关管数量、电容数量和冗余开关状态数量3个方面对比了新拓扑与普通有源中点箝位型拓扑的特性,最后以九电平组合拓扑为例,分析其工作原理、调制策略及电容电压控制策略。仿真和实验结果验证了其可行性。

Output levels of traditional multilevel inverter are difficult to expand. Considering that switched capacitors can generate double capacitor voltage, a novel seven-level inverter topology with switched capacitors is proposed in this paper. The topology can significantly increase the number of output levels. The redundancy states brought by the switched capacitor are beneficial to capacitor voltage equalization. Both the capacitor and the inverter are small in size, suitable for occasions of low voltage and high power density. The situations where the basic unit in the new topology is switched capacitor and flying capacitor respectively are analyzed. From the perspective of capacitance and cost, the principle of active neutral-point-clamped multilevel topology with switched capacitor is obtained. On this basis, the characteristics of the novel topology and common active neutral-point-clamped topology are compared from three aspects: the number of switching tubes, the number of capacitors and the number of redundant switching states. Finally, a nine-level new topology is taken as an example to analyze its working principle, modulation strategy and capacitor voltage control strategy. Simulation and experimental results verify feasibility of the proposed topology.