In recent years, modular multilevel converter (MMC) is considered for medium-voltage variable speed drives (VSD) due to its modularity and higher reliability. However, the major drawback of the MMC-based VSD is the higher capacitor ripple voltage at lower operating speeds. In literature, this ripple voltage is reduced by injecting a high-frequency circulating current into each arm. This additional circulating current increases the overall current rating of the devices, inductors, and capacitors. Alternatively, the capacitor ripple voltage can be reduced at the lower output frequency by reducing the dc-bus voltage. This paper proposes a new configuration using a multipulse diode-bridge rectifier to reduce the dc-bus voltage when the drive is operated at lower speeds. Therefore, the capacitor ripple voltage decreases without injecting any circulating current. In addition, a new technique is proposed to maintain the peak-to-peak value of the submodule capacitor ripple voltage constant at near-zero speed. The proposed converter with 24-pulse rectifier configuration is simulated in MATLAB/Simulink, and the experimental validation is carried out on a prototype with 12-pulse rectifier.

中文翻译：

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基于模块化多级转换器的变速驱动器，具有降低的电容器纹波电压


近年来，模块化多电平转换器（MMC）因其模块化和更高的可靠性而被考虑用于中压变速驱动器（VSD）。然而，基于 MMC 的 VSD 的主要缺点是在较低运行速度下电容器纹波电压较高。在文献中，通过向每个臂注入高频循环电流来降低纹波电压。这种额外的循环电流增加了器件、电感器和电容器的总体额定电流。或者，可以通过降低直流总线电压在较低输出频率下降低电容器纹波电压。本文提出了一种使用多脉冲二极管桥式整流器的新配置，以在驱动器以较低速度运行时降低直流总线电压。因此，电容器纹波电压降低，而无需注入任何环流。此外，还提出了一种新技术，可以在接近零速度时保持子模块电容器纹波电压的峰峰值恒定。所提出的具有 24 脉冲整流器配置的转换器在 MATLAB/Simulink 中进行了仿真，并在具有 12 脉冲整流器的原型上进行了实验验证。