基于MMC的高升压比直流变压器调制策略研究

现有的高压大功率DC/DC变换器研究开始更多地关注基于模块化多电平换流器MMC(modular multilevel converter)的face-to-face(F2F)拓扑。该拓扑由变压器连接两个模块化多电平换流器,易于根据电压等级扩展模块数量,因此,基于F2F的拓扑开始研究并应用在直流电网互联、新能源并网等领域。目前,基于该结构的直流变压器主要由其中频变压器提供变比。针对上述拓扑的特点,提出不依赖变压器变比的调制策略。采用该调制策略,可以灵活调节拓扑中各桥臂模块的通断改变电压变比,同时兼顾升压、降压功能。最后,在Matlab/Simulink中给出仿真算例,验证提出的方法的可行性。

Research on Modulation Strategy of High Voltage Ratio MMC Based DC Transformer

The present research on high-voltage and high-power DC/DC converter begins to pay more attention to the modular multi-level converter based on face-to-face(F2F) topology. The topology consists of two modular multi-level conver-ters connected by a transformer, which is easy to expand the number of modules according to the voltage level. Therefore, in the DC power grid interconnection, renewable power integration and other fields topology based on F2F began to have more research and application. At present, DC transformer based on this structure mainly provide variable ratio with the intermediate frequency transformer. Based on the characteristics of the topology above, this paper proposes a modulation strategy which does not depend on the transformer ratio. Using this modulation strategy, the voltage ratio can be adjusted by flexibly turning on/off the bridge arm module, which can make it have boost and buck function. Finally, a simulation example is given in Matlab/Simulink to verify the feasibility of the proposed method.