Circulating current exists among phases or between the DC link and the three phases in a modular multilevel converter (MMC). Suppression control of the alternating components in circulating current is a critical issue for the stable and efficient operation of an MMC. Due to the redundancy and symmetry of MMCs, some of the self-redundant states of MMCs can be used to suppress the alternating components in circulating current without affecting the output performance of the converter. In this paper, a theoretical derivation of the boundary of redundant states is given. Then a suppression strategy for circulating current is proposed based on prediction control and the boundary of redundant states. The selection range of the redundant states is narrowed in this case, which reduces the computation burden when compared to the original method and ensures excellent performance in the suppression of circulating current. Simulations and experiments are carried out to verify the effectiveness of the proposed strategy.

中文翻译：

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基于受限自冗余状态预测的模块化多电平换流器环流抑制控制

循环电流存在于模块化多电平转换器 (MMC) 中的相之间或直流链路与三相之间。对循环电流中的交流分量的抑制控制是 MMC 稳定高效运行的关键问题。由于MMCs的冗余性和对称性，MMCs的一些自冗余状态可以用来抑制环流中的交变分量，而不会影响转换器的输出性能。在本文中，给出了冗余状态边界的理论推导。然后提出了一种基于预测控制和冗余状态边界的环流抑制策略。在这种情况下，冗余状态的选择范围变窄了，与原始方法相比，减少了计算负担，并确保了在抑制环流方面的优异性能。进行仿真和实验以验证所提出策略的有效性。