The modular multilevel converter (MMC) is a promising topology for high-power converters. The capacitor voltage balancing method for the submodules (SMs) is one of the key technologies in terms of modular multilevel converters. Aiming at the problems of the large calculation burden and the high switching frequency in the traditional capacitor voltage balancing method, an improved balancing method based on a novel selection algorithm for MMCs is proposed in this paper. The proposed method can avoid the sorting operation of the arm SM voltages in each control cycle without reducing the control precision of the capacitor voltages. In addition, it greatly improves the sorting efficiency. Thus, a criterion for algorithm rerun is introduced, which makes the MMC controller avoid reordering the capacitor voltages and leave the control signals unchanged when the capacitor voltages experience small changes. Finally, simulation and experimental results confirm the feasibility and effectiveness of the proposed method.

模块化多电平转换器 (MMC) 是一种很有前途的大功率转换器拓扑结构。子模块（SM）的电容器电压平衡方法是模块化多电平转换器的关键技术之一。针对传统电容电压均衡方法计算量大、开关频率高的问题，提出一种基于新型MMCs选择算法的改进均衡方法。该方法在不降低电容器电压控制精度的情况下，避免了每个控制周期对臂SM电压的排序操作。此外，它大大提高了分拣效率。因此，引入了算法重新运行的标准，这使得 MMC 控制器避免重新排序电容器电压，并在电容器电压发生微小变化时保持控制信号不变。最后，仿真和实验结果证实了所提出方法的可行性和有效性。