A Capacitor Voltage Balancing Method With Fundamental Sorting Frequency for Modular Multilevel Converters Under Staircase Modulation
A Capacitor Voltage Balancing Method With Fundamental Sorting Frequency for Modular Multilevel Converters Under Staircase Modulation
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DOI：
10.1109/tpel.2016.2514524
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发表时间：
2016-01
影响因子：
6.7
通讯作者：
Hao Peng;Rui Xie;Kun Wang;Yan Deng;Xiangning He;R. Zhao
中科院分区：
文献类型：
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作者：
Hao Peng;Rui Xie;Kun Wang;Yan Deng;Xiangning He;R. Zhao
针对模块化多电平变换器的浮地电容平衡问题，提出了一种阶梯调制的基频分选算法。根据子模块对电容器的充电能力，在每个基本周期将驱动脉冲分配给子模块。驱动脉冲的充电能力可以通过对电容器的电压增量进行排序来评估，或者从电压增量与脉冲数之间的曲线的对称特性导出。采用这种方法，所有的功率器件在每个基波周期内仅切换一次，这适合于大功率应用。同时，分选频率降低到基频。因此，可以节省大量的计算资源。此外，它不需要测量臂电流，从而可以节省几个电流传感器，并可以简化中央和本地控制器之间的通信协议。最后，搭建了一个每臂20个子模块的三相仿真平台和一个每臂8个子模块的缩小实验样机，对所提出的电压平衡方法进行了验证。
A fundamental frequency-sorting algorithm with staircase modulation is proposed to balance the floating capacitors for modular multilevel converters. The driving pulses are assigned to the submodules at every fundamental period according to their charging capabilities for the capacitors. The charging capabilities of the driving pulses can be evaluated by sorting the voltage increments of the capacitors or derived from the symmetrical characteristic of the curve between the voltage increments and the pulse numbers. With this method, all the power devices switch only once per fundamental period, which is suitable for high-power applications. Meanwhile, the sorting frequency decreases to the fundamental frequency. Hence, a large number of calculation resources can be saved. Moreover, it does not need to measure the arm currents so that several current sensors can be saved and the communication protocol between the central and local controllers can be simplified. At last, a three-phase simulation platform with 20 submodules per arm and a down-scaled experimental prototype with eight submodules in each arm are built to validate the proposed voltage-balancing method.