The carrier phase-shift PWM strategy is widely used in modular multilevel converters to satisfy the driver demands of the numerous switches in submodules. However, the traditional carrier phase-shift PWM strategy can cause an imbalance phenomenon in the submodule capacitor voltages, which deteriorates the system working performance. This study develops a mathematical model of an MMC system, which is the basis of a quantitative analysis of the relations between the PWM strategy and the imbalance phenomenon. A novel method is then proposed to provide an accurate description of the cause of the imbalance phenomenon in relation to the PWM strategy. Based on the above analysis, a quantitative analysis of the imbalance phenomenon in the capacitor voltages is used to further measure the magnitudes of the imbalance phenomenon. The effect of the PWM strategy on the capacitor voltages is finally demonstrated via experiments.

中文翻译：

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MMC系统CPS-PWM策略引起的不平衡现象

载波移相PWM策略广泛应用于模块化多电平转换器，以满足子模块中众多开关的驱动需求。然而，传统的载波移相PWM策略会导致子模块电容电压出现不平衡现象，从而降低系统工作性能。本研究开发了 MMC 系统的数学模型，这是定量分析 PWM 策略与不平衡现象之间关系的基础。然后提出了一种新方法来准确描述与 PWM 策略相关的不平衡现象的原因。在上述分析的基础上，对电容器电压中的不平衡现象进行定量分析，以进一步衡量不平衡现象的大小。