Isolated Bipolar Modular Multilevel DC-DC Converter with Self-balancing Capability for Interconnection of MVDC and LVDC Grids  

作　　者：Jinmu Lai Xin Yin Yaoqiang Wang Lin Jiang Zia Ullah Xianggen Yin 

机构地区：[1]School of Electrical,and Information Engineering,Zhengzhou University,Zhengzhou 450001,China [2]Department of Electrical Engineering,and Electronics,University of Liverpool,Liverpool,UK [3]State Key Laboratory of Advanced Electromagnetic Engineering,and Technology,Huazhong University of Science,and Technology,Wuhan 430074,China

出　　处：《CSEE Journal of Power and Energy Systems》2023年第1期365-379,共15页中国电机工程学会电力与能源系统学报（英文）

基　　金：This work was supported in part by the National Natural Science Foundation of China(No.51877089)。

摘　　要：Bipolar medium-voltage DC(MVDC)and lowvoltage DC(LVDC)grids have the advantages of flexible integration of distributed renewable-energy generation and reliable power supply.In order to achieve voltage conversion,power transfer,and electrical isolation for bipolar MVDC and LVDC grids,a high-power DC-DC converter is essential.Therefore,this paper proposes an isolated bipolar modular multilevel DCDC converter(BiMMDC)with power self-balancing capability for interconnection of MVDC and LVDC grids.The proposed BiMMDC consists of two series connected MMCs in the MV stage to configure a bipolar MVDC interface,and interleaved converters combined with a dual-transformer are designed in the LV stage to configure the bipolar LVDC interface and to provide a self-balancing capability.Equivalent circuits of two series-connected MMCs and a dual-transformer with interleaved converters are derived.After that,operation principles of the proposed BiMMDC are introduced,considering balanced/unbalanced power transfer of bipolar LVDC grid and monopolar shortcircuit or open-circuit faults at MVDC grid.The control scheme is also presented for the proposed BiMMDC under different operating conditions.Finally,a Matlab simulation and controller hardware-in-the-loop(CHIL)evaluation results are provided to validate the feasibility and effectiveness of the proposed typology and its operating performance.

关 键 词：BIPOLAR DC-DC converter equivalent circuit MODULAR monopolar operation MULTILEVEL self-balancing 

分 类 号：TM4[电气工程—电器]