A Level-Increased Nearest Level Modulation Method for Modular Multilevel Converters

Hu, Pengfei; Jiang, Daozhuo

doi:10.1109/tpel.2014.2325875

Cited by 223 publications

(112 citation statements)

References 28 publications

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“…In addition, the level numbers of the arm voltages and output voltage all are increased to 2N+1. In addition, compared to the methods mentioned in [21] and [22], the sum of the upper and lower arm voltages with the proposed method is always equal to the bus voltage, which means that there is no pulse voltage across the arm inductors, and SM capacitor voltage is not decreased. Therefore, the arm inductor can be designed as a conventional MMC.…”

Section: A Principle Of Proposed Modulation Methodsmentioning

confidence: 97%

“…1, the arm of which consists of N series connected half-bridge submodules (HBSMs), one full-bridge submodule (FBSM) and an arm inductor. Compared with the conventional MMC topology with the NLM methods proposed in [21] and [22], the improved MMC topology with the proposed method is also able to increase the level number of the output voltage to 2N+1. Moreover, it keeps the total number of inserted SMs unchanged.…”

Section: Introductionmentioning

confidence: 99%

“…However, the switching frequency of the IGBTs is increased when compared to NLM. A modified NLM method proposed in [21] is used to shift the moments of the step changing in the upper and lower arm voltages. Another improved NLM method is presented in [22], which introduces an alternating offset into the reference signals of the upper and lower voltages.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, it keeps the total number of inserted SMs unchanged. As a result, the high inductor voltage pulses caused in [21] and [22] can be eliminated, and the SM capacitor voltage and output voltage are not decreased. In addition, the voltage balancing of the HBSM and FBSM capacitors are realized independently.…”

Section: Introductionmentioning

confidence: 99%

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A Hybrid Modular Multilevel Converter Topology with an Improved Nearest Level Modulation Method

Wang¹,

Han²,

Bai³

2017

Journal of Power Electronics

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In this paper, a hybrid modular multilevel converter (MMC) topology with an improved nearest level modulation method is proposed for medium-voltage high-power applications. The arm of the proposed topology contains N series connected half-bridge submodules (HBSMs), one full-bridge submodule (FBSM) and an inductor. By exploiting the FBSM, half-level voltages are obtained in the arm voltages. Therefore, an output voltage with a 2N+1 level number can be generated. Moreover, the total level number of the inserted submodules (SMs) is a constant. Thus, there is no pulse voltage across the arm inductors, and the SM capacitor voltage is rated. With the proposed voltage balancing method, the capacitor voltage of the HBSM is twice the voltage of the FBSM, and each IGBT of the FBSM has a relatively low switching frequency and an equalized conduction loss. The capacitor voltage balancing methods of the two kinds of SMs are implemented independently. As a result, the switching frequency of the HBSM is not increased compared to the conventional MMC. In addition, according to a theoretical calculation of the total harmonic distortion of the electromotive force (EMF), the voltage quality with the presented method can be significantly enhanced when the SM number is relatively small. Simulation and experimental results obtained with a MMC-based inverter verify the validity of the developed method.

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Section: A Principle Of Proposed Modulation Methodsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Hybrid Modular Multilevel Converter Topology with an Improved Nearest Level Modulation Method

Wang¹,

Han²,

Bai³

2017

Journal of Power Electronics

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“…PWM methods, including carrier-phase-shifted PWM [12], submodule (SM) unified PWM [13], and selective harmonic elimination method [14], share some common features, such as high switching frequency, large switching losses, and complex implementation process. Unlike the aforementioned methods, the nearest level modulation (NLM) method [15] does not need a complex calculation of the trigger angles. Therefore, NLM is the simplest and the most practical modulation method for MMC.…”

Section: Introductionmentioning

confidence: 99%

On DC-Side Impedance Frequency Characteristics Analysis and DC Voltage Ripple Prediction under Unbalanced Conditions for MMC-HVDC System Based on Maximum Modulation Index

Liu¹,

Chen²,

Li³

et al. 2016

Journal of Power Electronics

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In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.

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Model Predictive Control of a Modular Multilevel Converter

2016

Model Predictive Control of High Power Convertersand Industrial Drives

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in 2016, otherwise this dissertation would not come true. He gave me the freedom to choose the doctoral topic in the beginning of my study and encouraged me when I faced problems. I really appreciate his support throughout my doctoral period. Furthermore, I'd like to thank Prof. José Rodríguez (Universidad San Sebastián, Chile) for agreeing to be the co-examiner of my dissertation and his valuable suggestions for improving the quality of my dissertation. It is my great pleasure to work with the colleagues at EAL. They gave me support in both my academic research and daily life in Germany. First of all, I feel grateful to Mr. Wei Tian. Without his help, our testbench could not be constructed. Many thanks to Dr.-Ing. Zhenbin Zhang and Dr.-Ing. Xinbo Cai, they gave me valuable guidance on my work. Also, I'd like to express my gratitude to Mr. Yuebin Pang Mr. Ding Dai and Dr. Genji Pei for their support when I was setting up the testbench. Dr.

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A Level-Increased Nearest Level Modulation Method for Modular Multilevel Converters

Cited by 223 publications

References 28 publications

A Hybrid Modular Multilevel Converter Topology with an Improved Nearest Level Modulation Method

A Hybrid Modular Multilevel Converter Topology with an Improved Nearest Level Modulation Method

On DC-Side Impedance Frequency Characteristics Analysis and DC Voltage Ripple Prediction under Unbalanced Conditions for MMC-HVDC System Based on Maximum Modulation Index

Model Predictive Control of a Modular Multilevel Converter

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