Research On Control System Of Modular Multilevel Converter

As power electronic used more and more in the field of Energy Conservation Intelligent Power Grid in recent years, device of high voltage and high power rate was pay more and more attention to. Modular Multilevel Converter(MMC) emerged under this background. This article choose control system of this topology as research object, and pay moer attention on modulation method, dead-time effect and controller architecture.The modulation suitable for MMC will be discussed in this article, such as selection mechanism modulation and carrier phaseshift modulation. After that, some comparion between modulation method will be compared from the THD and circulating current. Then the dead-time effect of MMC was proposed and analysis, and the method for dead-time compensation was discussed.A three-level controller made up of DSP+FPGA+MCU is discussed in this article to reduce the fiber optic and achive the flexibility of the module. Meanwhile it analyses and gives a solution of module asynchronous phenomemon caused by this special controller.The validity of the proposed controller architecture is verified by experimental results obtained from a one phase prototype of 6 modules, using the selection mechanism modulation and voltage balancing strategy, and then the experimental results of dead-time compensation also gave in the article.