A Simple Capacitor Voltage Balancing Method with a Fundamental Sorting Frequency for Modular Multilevel Converters

A Fundamental Frequency Sorting Algorithm (FFSA) is proposed in this paper to balance the voltages of floating dc capacitorsfor Modular Multilevel Converters (MMCs). The main idea is to change the sequences of the CPS-PWM carriers according to thecapacitor voltage increments during the previous fundamental period. Excessive frequent sorting is avoided and many calculatingresources are saved for the controller. As a result, more sub-modules can be dealt with. Furthermore, it does not need to measure thearm currents. Therefore, the communication between the controllers can be simplified and the number of current sensors can bereduced. Moreover, the proposed balancing method guarantees that all of the switching frequencies of the sub-modules are equal toeach other. This is quite beneficial for the thermal design of the sub-modules and the lifetime of the power switches. Simulation andexperimental results acquired from a 9-level prototype verify the viability of the proposed balancing method.

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Cite this article

[IEEE Style]

H. Peng, Y. Wang, K. Wang, Y. Deng, X. He, R. Zhao, "A Simple Capacitor Voltage Balancing Method with a Fundamental Sorting Frequency for Modular Multilevel Converters," Journal of Power Electronics, vol. 14, no. 6, pp. 1109-1118, 2014. DOI: 10.6113/JPE.2014.14.6.1109.

[ACM Style]

Hao Peng, Ying Wang, Kun Wang, Yan Deng, Xiangning He, and Rongxiang Zhao. 2014. A Simple Capacitor Voltage Balancing Method with a Fundamental Sorting Frequency for Modular Multilevel Converters. Journal of Power Electronics, 14, 6, (2014), 1109-1118. DOI: 10.6113/JPE.2014.14.6.1109.