新型模块化多电平DC-DC变换器拓扑及其工作机理分析

针对目前模块化多电平DC-DC变换器拓扑结构及其主要采用的交流平衡控制方法所带来的问题,基于直流控制思想,提出了一种新型模块化多电平DC-DC变换器拓扑。通过重构一种全桥子模块结构,每个子模块电容同时包含两条充放电路径,相邻子模块间通过形成局部的并联支路实现电容间电能传递和电容电压自平衡,避免了子模块电容在单向直流电能变换导致的电压失衡。通过对变换器的平衡机理及其基本工作原理分析、仿真实验验证,结果表明所提出的变换器在直流控制方式下能够稳定运行,子模块电容电压具有自平衡能力,变换器电压变比范围大,具有适用于不同应用场合直流输配电的应用潜力。

Topology and Mechanism Analysis of Novel Modular Multilevel DC-DC Converter

For the present problems brought about by modular multilevel DC-DC converter topology and its AC balance control idea, a novel module multilevel DC-DC converter topology based on the DC control idea is proposed. By reconstructing the full-bridge submodules, each submodule capacitor contains two charging and discharging paths. The capacitors can perform power transfer and voltage self-balance through a local parallel branch formed between adjacent submodules, so as to avoid the voltage unbalance of the capacitors in the unidirectional DC power conversion. The analysis and simulation test of the balance mechanism and the basic principles of the converter show that the proposed converter can operate stably in the DC control mode, the capacitor voltage can be self-balanced, the conversion ratio is big and has the potential to be used in the different applications of DC transmission and distribution. This work is supported by National Natural Science Foundation of China(No. 51490681)and National Basic Research Program of China(973 Program)(No. 2015CB251004).