模块化多电平变换器全桥型子模块优化均压控制方法

模块化多电平变换器(MMC)子模块(SM)的数量与直流侧电压成正比,当SM增加时,会导致MMC的开关损耗急剧增加,因此降低功率器件的开关频率一直是MMC的重要研究方向之一。采用最近电平逼近调制(NLM)方式,提出一种基于全桥型SM的改进均压排序法,旨在降低MMC中功率器件IGBT的开关频率,该方法实现相对简单,无需额外的控制器,且易于扩展。最后,通过在MATLAB/Simulink平台搭建了19个全桥SM的仿真模型,验证了该方法的有效性。验证了所提全桥型SM优化均压策略,可以有效避免IGBT不必要的反复投切,降低IGBT的开关损耗,同时对外部输出特性不会产生负面影响。

Optimization of Voltage Sharing Control Method for Full-Bridge Sub-Module of Modular Multilevel Converter

The number of modular multilevel converter (MMC) sub-modules (SMs) is proportional to the voltage of DC side. When the SM number increases, the switching loss of MMC will increase sharp, so reducing the switching frequency of power devices has been an important research direction of MMC. The nearest level modulation (NLM) is adopted and an improved equal-voltage ranking method based on a full-bridge SM is proposed, aiming to reduce the switching frequency of IGBT in MMC. This method is relatively simple, requires no additional controller and is easy to be extended. Then, 19 simulation models of full-bridge SM are built on MATLAB/Simulink platform to verify the effectiveness of the method. It is verified that the proposed full-bridge SM optimization voltage-sharing strategy can effectively avoid unnecessary repeated switching of IGBT, reduce the switching loss of IGBT, and have no negative effects on the external output characteristics.