Research on Control Strategy of Bidirectional Modular Multilevel DC-DC Converter

Bidirectional modular multilevel DC-DC converter has received extensive attention because of its advantages of electrical isolation, flexible control of DC power, and high voltage and high-power applications. A control strategy for bidirectional modular multilevel DC-DC converter is presented in this paper. The control strategy adopts the constant AC and DC voltage control to realize the control of the converters active and reactive power in the overall control. The valves control adopts the method which produces the trigger pulse firstly, then sorts and balances the voltage of sub modules(SMs) to achieve the balance of the energy of the converters arm. The Matlab/Simulink simulation shows that the converter can obtain a stable DC output voltage under the proposed control strategy. The capacitor voltages of SMs are well balanced. At the same time, the switching frequency of each SM is also consistent, and the result is ideal.