Abstract：This paper analyzes the topology and operation characteristics of MMC-H bridge DC transformer based on modular multilevel converter (MMC) arm and H-bridge, where the MMC adopts staircase modulation and the H-bridge adopts an extended phase shift modulation with an added phase shift. Besides, this paper deduces the expression of the voltage and current of the AC chain inthe DC transformer. The expression of transmission power and algorithm of backflow power are deduced, and the distribution of power variation with parameters is analyzed. The factors that affect the backflow power are summarized, and the optimized voltage regulation ratio is discussed. Zero-backflow-power boundary conditions and backflow power optimized working area are condensed. In order to suppress the backflow power, this paper proposes a backflow power optimized strategy that DC transformer works in the optimized working area by adjusting of the inner/outer phase-shift, which reduces the backflow power and current stress. Finally, a physical prototype is built to verify the optimized strategy by experimental results.
管州, 梅军, 丁然, 葛锐, 范光耀. 基于拓展移相控制的直流配电网模块化多电平直流变压器[J]. 电工技术学报, 2019, 34(13): 2770-2781.
Guan Zhou, Mei Jun, Ding Ran, Ge Rui, Fan Guangyao. Modular Multilevel DC Transformer for DC Distribution Application Based on Extended Phase-Shift Control. Transactions of China Electrotechnical Society, 2019, 34(13): 2770-2781.
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2019, Vol. 34 
