A Coordinated Strategy of Low-Speed and Start-Up Operation for Medium-Voltage Variable-Speed Drives With a Modular Multilevel Converter

Zhao, Fulong; Xiao, Guochun; Zhu, Tianhua; Xu, Zheng; Wu, Zhonghua; Zhao, Tong

doi:10.1109/tpel.2019.2913696

Cited by 47 publications

(39 citation statements)

References 29 publications

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“…where Δu cx j represents the SM capacitor voltage ripple in xphase j arm when ūcxji = U dc ∕N . From formula (8) (9) (25), we can get (27), and m represents the modulation, m = 2U m ∕U dc .…”

Section: Mathematical Analysis For the Sm Capacitor Voltage Ripplementioning

confidence: 99%

“…Therefore, using formula (27), take the maximum and minimum fluctuation values in the fundamental frequency period of a single ac power grid, and use formula (28a) to calculate the SM capacitor voltage ripple when 𝜂 x ji = 1. Then, according to formulas (28b) and ( 29), 𝜀 x ji and Δu P cx ji can be obtained.…”

Section: Mathematical Analysis For the Sm Capacitor Voltage Ripplementioning

confidence: 99%

“…The current SM capacitor ripple analysis of the MMC mainly focuses on the typical MMC topology [23][24][25][26][27][28][29][30][31], and focuses on analysing the SM capacitor voltage ripple and its low frequency ripple suppression. There are few analyses on the capacitor ripple of SMs connected to PV panels or other distributed generators.…”

Section: Introductionmentioning

confidence: 99%

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Unbalanced power control of a modular multilevel converter with photovoltaic resources and the capacitor voltage ripple analysis

Liu

Zhang

Wang

et al. 2022

IET Power Electronics

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The modular multilevel photovoltaic (PV) converter can achieve independent power control and help to increase the efficiency of the system. However, the output power among PV modules is unbalanced, which will result in the power loss of system if not properly controlled. This paper first introduces a power control scheme to adjust the power distribution among dc grid, ac grid and PV modules, and presents the mathematical bases of the scheme and the unbalanced power control of the strategy. However, the voltage ripple of MMC sub module (SM) capacitor is also an important parameter. In this system, the SM voltage ripple has not been analysed in relevant articles. Because there are many variables, it is not easy to analyse. Here, the voltage ripple law of the SM capacitor is analysed, by simplifying variables and presenting a fast analytical method, which has reference significance for the selection of SM capacitor. Matlab simulation and the hardware in the loop simulation experiment built by StarSim of Modelling Tech verify the effectiveness of the introduced control strategy and the correctness of the SM capacitor ripple analysis.

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Section: Mathematical Analysis For the Sm Capacitor Voltage Ripplementioning

confidence: 99%

Section: Mathematical Analysis For the Sm Capacitor Voltage Ripplementioning

confidence: 99%

See 1 more Smart Citation

Unbalanced power control of a modular multilevel converter with photovoltaic resources and the capacitor voltage ripple analysis

Liu

Zhang

Wang

et al. 2022

IET Power Electronics

View full text Add to dashboard Cite

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“…Compared to other converters, MMCs have the advantages of having a high degree of modularity, low redundancy costs, and high efficiency; thus, it has great developmental prospects [6][7][8]. However, the capacitor voltages of MMCs fluctuate greatly since the capacitors are always charged or discharged during operation, and the voltage ripple amplitude is inversely proportional to the operating frequency of the MMC [9]. Excessive voltage fluctuations lead to power imbalances within the MMC and may even deteriorate the output waveform of the MMC.…”

Section: Introductionmentioning

confidence: 99%

Voltage Ripple Suppression Methods for the Capacitor in Modular Multilevel Converter Submodules Employing a Reversed Pulse Width Modulation-Switching Channel

2022

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Modular multilevel converters (MMCs) will be widely applied in onboard integrated power systems due to their high levels of electric power output and good-quality sine waveform outputs. However, the capacitor voltage of MMCs fluctuates greatly because the charge–discharge process of the capacitor is continuous when the system is working. In order to reduce voltage ripples efficiently, a capacitor voltage ripple-suppression strategy employing a reversed PWM switching channel is proposed in this paper. For one pair of the upper and lower arm submodules, a switching channel is built. Then, the highest ripple voltage possible can be offset since the voltage fluctuation direction of the upper and the lower arm capacitors would be reversed. In addition, a clamping capacitor is added to the switching channel to further suppress the fluctuation voltage by 78%. Compared to traditional large capacitance suppression methods, only 12% capacitance is used in the proposed method. The reliability and power density of the proposed MMC both increased, and there are no additional losses compared with previous voltage ripple suppression methods. The effectiveness of the proposed voltage ripple suppression strategy is verified by simulation results.

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“…The high-frequency common-mode voltage (CMV) and circulating current have been injected into the three-phase legs of MMCs, which can mitigate SM capacitor voltage ripples. However, the CMV exists on the motor side, which leads to premature failure of the winding insulation and motor bearing [17], [18].…”

Section: Introductionmentioning

confidence: 99%

Reduction of Half-Arm Current Stresses and Flying-Capacitor Voltage Ripples of Flying-Capacitor MMCs

Lee

2020

IEEE Access

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In this paper, a new control scheme that can reduce the current stresses on switching devices, flying capacitors, and inductors for flying-capacitor modular multilevel converters (FC-MMCs) is proposed, which is based on redistribution of power difference between upper and lower arms through the flying capacitors. In addition, a way to determine the frequency range of the square-wave voltage to be injected into the FC-MMC is suggested, which is able to improve the current control performance and reduce the flyingcapacitor voltage ripples. The effectiveness of the proposed control scheme has been verified for a 4160-V/1-MW simulation model and a 230-V/3-kW prototype of the FC-MMC. INDEX TERMS Arm current, medium-voltage motor drive, modular multilevel converters (MMC), submodule (SM) capacitor voltage ripple.

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A Coordinated Strategy of Low-Speed and Start-Up Operation for Medium-Voltage Variable-Speed Drives With a Modular Multilevel Converter

Cited by 47 publications

References 29 publications

Unbalanced power control of a modular multilevel converter with photovoltaic resources and the capacitor voltage ripple analysis

Unbalanced power control of a modular multilevel converter with photovoltaic resources and the capacitor voltage ripple analysis

Voltage Ripple Suppression Methods for the Capacitor in Modular Multilevel Converter Submodules Employing a Reversed Pulse Width Modulation-Switching Channel

Reduction of Half-Arm Current Stresses and Flying-Capacitor Voltage Ripples of Flying-Capacitor MMCs

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