MMC中全桥子模块损耗分布优化的调制方法研究

An Optimal Strategy for Loss Distribution of Full-bridge Submodules in Modular Multilevel Converters

为了提高全桥子模块的运行可靠性,该文研究全桥子模块的损耗分布,并提出一种损耗分布优化的控制方法。首先,根据全桥子模块的输出特性及其器件的损耗特征推导出子模块损耗分布的解析表达式,由此揭示出功率输出对损耗的影响。其次,根据损耗分布表达式,分析全桥子模块冗余开关状态对损耗分布的影响,确定可实现损耗均衡的冗余开关状态投切原则。最后,为了实现上述投切原则,引入轮换及结温反馈两种调制方法对开关状态投切进行控制,并通过仿真验证损耗分布分析的正确性及所提方法的有效性。

In order to promote the reliability of the full bridge submodule, its loss distribution as well as its loss balance strategy was investigated. At first, through a theoretical analysis method, the loss distribution in full-bridge sub-module was derived and the fundamental factor that causes loss imbalance was disclosed. And then, the effects of redundant switching states on loss distribution in full bridge submodule were investigated. As a result, the optimal principle about how to use redundant switching state to relive imbalance loss distribution was proposed. Finally, in order to achieve the optimal switching principle, the loss balance strategy based on online loss calculation was addressed. Meanwhile, above analysis were also verified by PLECS simulation results.