An improved control method applied to the DC/DC converter based on MMC

Recent research on high voltage and power DC/DC converter mainly focus on the face-to-face topology based on modular multilevel converters (MMC). The topology consists of two MMC which are coupled by a transformer. It is easy to extend the module number according to the voltage level. However, the present modulation method in this topology cannot regulate the voltage transformation ratio on two dc sides. The ratio of the dc voltage mainly depends on the transformer ratio. This paper proposes a modulation method which can adjust the dc voltage ratio directly. Finally, a simulation model is established to verify the feasibility of the method.