七电平逆变器电容电压自均衡控制策略研究

Research on the Control Strategy of Capacitor Voltage Self-balance for Seven-level Inverter

在传统多电平逆变器的基础上,采用一种基于开关电容的新型七电平逆变器拓扑,针对此结构提出了一种改进型的同相层叠(in-phase disposition,IPD)载波调制方法。该策略通过调整传统IPD调制载波在正弦调制波周期内水平方向的自由度,减少了半数的载波,大幅降低控制的难度,对其中的两个载波进行周期性互换,从而实现开关电容的电压自均衡。同时以单相七电平逆变器为例,对该结构的效率进行了详细的分析。最后通过搭建相应的Matlab/Simulink仿真和小功率实验平台验证调制方法和拓扑结构的有效性和实用性。

A new seven-level inverter topology based on switched capacitors is adopted on the basis of traditional multi-level in-verter,and an improved In-Phase Disposition(IPD)carrier control is proposed for this structure.In this strategy,half of the carriers can be reduced by adjusting the degree of freedom of the traditional IPD modulation carrier in the horizon-tal direction within the sinusoidal modulation wave cycle,thus the difficulty of control is greatly reduced;meanwhile,the two carriers are periodically interchanged to realize the voltage self-equalization of the switched capacitor.At the same time,a single-phase seven-level inverter is taken as an example,the efficiency of the structure is studied in detail,and the validity and practicability of this control strategy are proved through the analysis of Matlab/Simulink simulation and experimental results.