An enhanced level-increased nearest level modulation for modular multilevel converter

Si, Gangquan; Zhu, Jianwei; Lei, Yuhang; Jia, Lixin; Zhang, Yanbin

doi:10.1002/etep.2669

Cited by 9 publications

(7 citation statements)

References 25 publications

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“…And with the exposure of SM to all PWM pulses, the ON and off mode of the SM are equal over N fundamental cycles. These are given by Equation (10).…”

Section: The Mathematical Approach Of Voltage Balancing Methodsmentioning

confidence: 99%

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A level enhanced voltage balancing method for modular multilevel converter without using sensors

Gobburi

Borghate

Meshram

2022

Circuit Theory & Apps

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The intrinsic characteristics such as modular structure, filterless operation, and absence of DC-link capacitor have made the modular multilevel converter (MMC) superior to the conventional multilevel converters. However, the submodule (SM) capacitor voltage balancing is crucial. This paper presents a voltage balance control method for MMC. The proposed method generates 2N + 1 levels (where N is the number of SMs per arm) which halves the step size of output voltage and improves the harmonic performance as compared to N + 1 level generation. It requires only one carrier per phase and no voltage and current measurements are needed for the implementation. Therefore, the proposed method makes the system cost-effective and reduces the implementation issues related with carrier-based methods substantially. It also alleviates the non-uniform charge distribution problem with the phase disposition pulse width modulation (PDPWM) technique. Further, a detailed mathematical analysis is presented which enhances the understanding of balancing algorithm. In addition to this, the circulating current with 2N + 1 modulation is analyzed and a control technique is presented. The proposed voltage balancing method is simulated comprehensively in MATLAB/SIMULINK software and validated by the experimental results obtained from a laboratory prototype.

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“…And with the exposure of SM to all PWM pulses, the ON and off mode of the SM are equal over N fundamental cycles. These are given by Equation (10).…”

Section: The Mathematical Approach Of Voltage Balancing Methodsmentioning

confidence: 99%

“…The selective harmonic elimination-pulse width modulation (SHE-PWM) and nearest level control (NLC) are the low-switching frequency methods. [8][9][10][11] In Xin et al, 8 a new approach of SHE-PWM is proposed and generated 2N + 1 levels at load side. However, it has to find the optimal firing angles.…”

Section: Introductionmentioning

confidence: 99%

A level enhanced voltage balancing method for modular multilevel converter without using sensors

Gobburi

Borghate

Meshram

2022

Circuit Theory & Apps

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“…The results show a significantly improved THD, however, the study does not discuss applying the method to a reduced number of levels (less than 21). After a precise review of the literature, it was found that few studies have been conducted on the NLC method applied to the TCHB inverter compared to MMC [22][23][24][25] and asymmetrical CHB MLI [7,21]; Therefore, this paper focuses on applying the NLC method to a 13 level A-TCHB inverter with a DC voltage ratio 1: 2 between two TCHB cells. The method operates at the fundamental frequency and can be extended to any number of levels.…”

Section: Issn: 2088-8694 mentioning

confidence: 99%

Harmonic minimization of a single-phase asymmetrical TCHB multilevel inverter based on nearest level control method

Saleh¹,

Said²,

Halim³

2020

IJPEDS

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Multilevel inverters are gaining special interest among researchers and in the industry due to their widespread applications and numerous merits. Obtaining high quality, more reliable output while using a reduced number of electronic components is the main purpose of most of the research conducted in this area of study. The purpose of this study is to apply the nearest level control (NLC) method to a 13-level transistor-clamped H-bridge (TCHB) inverter with unequal DC voltage supplies. The NLC method operates at the fundamental frequency, thus reducing switching losses, and can reduce the harmonic content significantly. The adopted multilevel inverter consists of two TCHB cells supplied with two asymmetrical DC input sources with a voltage ratio of 1:2. This structure reduces the number of electronic components, and the asymmetry in the DC input voltages results in a higher number of levels. The adopted topology and its proposed control method were simulated in Matlab/Simulink, and the simulation results were verified through experiments using an Altera field-programmable gate array (FPGA) board. The results showed that the topology and its control method are efficient in obtaining a high-quality output with an improved total harmonic distortion (THD).

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“…In [37], output voltage quality can be boosted by combining the NLM and carrier-based PWM method, which causes increase in the switching losses compared with the C-NLM method. e main objective of [38] is to introduce a new NLM method for improving output performance of MMC with increase in the level number. Feasibility of the proposed method is confirmed by simulation results by comparing it with C-NLM for MMC with a large number of SMs.…”

Section: Introductionmentioning

confidence: 99%

A Novel Nearest Level Modulation Method with Increased Output Voltage Quality for Modular Multilevel Converter Topology

Kurtoğlu

Vural

2022

International Transactions on Electrical Energy Systems

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The modular multilevel converter (MMC) topology is gaining more interest because of its modular design, high efficiency, and scalable voltage levels in medium- and high-power industrial applications, where the nearest level modulation (NLM) method is frequently preferred. In this paper, a novel NLM method is proposed with increased output voltage quality for MMC topology. In conventional NLM (C-NLM), output voltage is obtained as N + 1 levels, where N is the number of submodules (SMs) per arm. The output voltage is increased to 2N + 1 levels by the proposed NLM method without using any additional SMs. The proposed NLM method is based on the offset term injection, which is optimally determined in terms of the best output performance of MMC. Also, trapezoidal reference signal is used instead of sinusoidal reference, which provides better output voltage quality and controls the modulation process. The proposed NLM method presents simple implementation as in the C-NLM, and it is implemented to the upper and lower arms of the MMC; then, arm voltages are successfully controlled. Furthermore, output voltage returns the value of zero in the C-NLM process for low-modulation-ratio applications in relatively small amount of SM usage of MMC design. However, the proposed NLM method gives promising results instead of zero voltage. In order to validate the superior performance of the proposed NLM method, a comparative study is presented with C-NLM and third-harmonic injected NLM method in terms of total harmonic distortion (THD) and magnitude of the output voltage and current. THD of output waveforms of MMC is significantly reduced, and DC voltage utilization is remarkably increased, thanks to the proposed NLM method. In addition, capacitor voltage balancing for the proposed NLM method is accomplished to keep the capacitor voltage of each SM of MMC constant. Simulation results are presented to verify the effectiveness of the proposed NLM method under various case studies. Finally, experimental validation is carried out using a field programmable gate array (FPGA)-based hardware implementation on the laboratory prototype to show the applicability of the proposed NLM method.

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An enhanced level-increased nearest level modulation for modular multilevel converter

Cited by 9 publications

References 25 publications

A level enhanced voltage balancing method for modular multilevel converter without using sensors

A level enhanced voltage balancing method for modular multilevel converter without using sensors

Harmonic minimization of a single-phase asymmetrical TCHB multilevel inverter based on nearest level control method

A Novel Nearest Level Modulation Method with Increased Output Voltage Quality for Modular Multilevel Converter Topology

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