In order to ensure the safe and reliable operation of three-phase four-wire (3P4W) three-level grid-connected converter (TL-GCC) from the point view of neutral point voltage (NPV) self-equilibrium, a sufficient condition based on carrier-based pulse width modulation (CBPWM) strategy is presented. The analysis of NPV self-equilibrium based on the sufficient condition is presented while different forms of current are outputted. Then, a novel active control method based on producing zero sequence direct current is proposed to balance NPV. The theoretical analysis of NPV self-equilibrium as well as the effectiveness of the proposed active NPV control method are verified by experimental results.

中文翻译：

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基于CBPWM策略的三相四线三电平并网变流器中性点电压分析


为了从中性点电压（NPV）自平衡的角度保证三相四线（3P4W）三电平并网变流器（TL-GCC）安全可靠运行，基于充分条件提出了基于载波的脉宽调制（CBPWM）策略。给出了输出不同形式电流时基于充分条件的NPV自平衡分析。然后，提出了一种基于产生零序直流电的新型主动控制方法来平衡NPV。实验结果验证了NPV自平衡的理论分析以及所提出的主动NPV控制方法的有效性。