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Journal ArticleDOI

A Survey on Neutral-Point-Clamped Inverters

TL;DR: The basic operation and the most used modulation and control techniques developed to date of neutral-point-clamped inverters are presented and some technological problems such as capacitor balance and losses are presented.
Abstract: Neutral-point-clamped (NPC) inverters are the most widely used topology of multilevel inverters in high-power applications (several megawatts). This paper presents in a very simple way the basic operation and the most used modulation and control techniques developed to date. Special attention is paid to the loss distribution in semiconductors, and an active NPC inverter is presented to overcome this problem. This paper discusses the main fields of application and presents some technological problems such as capacitor balance and losses.
Citations
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Journal ArticleDOI
TL;DR: In this paper, power converters are classified into single and multicell topologies, with attention to series connection and parallel connection either electrical or magnetic ones (multiphase/windings machines/transformers).
Abstract: The steady growth of installed wind power together with the upscaling of the single wind turbine power capability has pushed the research and development of power converters toward full-scale power conversion, lowered cost pr kW, increased power density, and also the need for higher reliability. In this paper, power converter technologies are reviewed with focus on existing ones and on those that have potential for higher power but which have not been yet adopted due to the important risk associated with the high-power industry. The power converters are classified into single- and multicell topologies, in the latter case with attention to series connection and parallel connection either electrical or magnetic ones (multiphase/windings machines/transformers). It is concluded that as the power level increases in wind turbines, medium-voltage power converters will be a dominant power converter configuration, but continuously cost and reliability are important issues to be addressed.

797 citations


Cites background from "A Survey on Neutral-Point-Clamped I..."

  • ...However, it is found that the loss distribution is unequal between the outer and inner switching devices in a switching arm, and this problem might lead to de-rated converter power capacity when it is practically designed [42], [44]....

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  • ...However, this problem has been extensively researched and is considered solved by the controlling of redundant switching status [42]....

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Journal ArticleDOI
TL;DR: In this paper, the authors give an overview and discuss some development trends in the technologies used for wind power systems, and several state-of-the-art wind turbine concepts, as well as the corresponding power electronic converters and control structures are reviewed, respectively.
Abstract: Wind power is still the most promising renewable energy in the year of 2013. The wind turbine system (WTS) started with a few tens of kilowatt power in the 1980s. Now, multimegawatt wind turbines are widely installed even up to 6-8 MW. There is a widespread use of wind turbines in the distribution networks and more and more wind power stations, acting as power plants, are connected directly to the transmission networks. As the grid penetration and power level of the wind turbines increase steadily, the wind power starts to have significant impacts to the power grid system. Therefore, more advanced generators, power electronic systems, and control solutions have to be introduced to improve the characteristics of the wind power plant and make it more suitable to be integrated into the power grid. Meanwhile, there are also some emerging technology challenges, which need to be further clarified and investigated. This paper gives an overview and discusses some development trends in the technologies used for wind power systems. First, the developments of technology and market are generally discussed. Next, several state-of-the-art wind turbine concepts, as well as the corresponding power electronic converters and control structures, are reviewed, respectively. Furthermore, grid requirements and the technology challenges for the future WTS are also addressed.

736 citations


Cites background from "A Survey on Neutral-Point-Clamped I..."

  • ...It is, however, found that the loss distribution is unequal between the outer and inner switching devices in a switching arm [24]–[26], and this problem might lead to a derated power capacity when it is practically used....

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Journal ArticleDOI
18 May 2015
TL;DR: The most successful generator-converter configurations are addressed along with few promising topologies available in the literature from the market based survey, and the past, present and future trends in megawatt WECS are reviewed in terms of mechanical and electrical technologies, integration to power systems, and control theory.
Abstract: This paper presents a comprehensive study on the state-of-the-art and emerging wind energy technologies from the electrical engineering perspective. In an attempt to decrease cost of energy, increase the wind energy conversion efficiency, reliability, power density, and comply with the stringent grid codes, the electric generators and power electronic converters have emerged in a rigorous manner. From the market based survey, the most successful generator-converter configurations are addressed along with few promising topologies available in the literature. The back-to-back connected converters, passive generator-side converters, converters for multiphase generators, and converters without intermediate dc-link are investigated for high-power wind energy conversion systems (WECS), and presented in low and medium voltage category. The onshore and offshore wind farm configurations are analyzed with respect to the series/parallel connection of wind turbine ac/dc output terminals, and high voltage ac/dc transmission. The fault-ride through compliance methods used in the induction and synchronous generator based WECS are also discussed. The past, present and future trends in megawatt WECS are reviewed in terms of mechanical and electrical technologies, integration to power systems, and control theory. The important survey results, and technical merits and demerits of various WECS electrical systems are summarized by tables. The list of current and future wind turbines are also provided along with technical details.

694 citations


Cites background from "A Survey on Neutral-Point-Clamped I..."

  • ...With this arrangement, the converter output phase voltage contains three levels leading to reduced dv=dt and electromagnetic interference than 2L-VSCs [126], [127], [146], [147]....

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Journal ArticleDOI
TL;DR: Reduction in the number of power switches, driver circuits, and dc voltage sources is the advantage of the developed single-phase cascaded multilevel inverter, and the installation space and cost of the inverter are reduced.
Abstract: In this paper, a new single-phase cascaded multilevel inverter is proposed. This inverter is comprised of a series connection of the proposed basic unit and is able to only generate positive levels at the output. Therefore, an H-bridge is added to the proposed inverter. This inverter is called the developed cascaded multilevel inverter. In order to generate all voltage levels (even and odd) at the output, four different algorithms are proposed to determine the magnitude of dc voltage sources. Reduction in the number of power switches, driver circuits, and dc voltage sources is the advantage of the developed single-phase cascaded multilevel inverter. As a result, the installation space and cost of the inverter are reduced. These features are obtained by the comparison of the conventional cascaded multilevel inverters with the proposed cascaded topology. The ability of the proposed inverter to generate all voltage levels (even and odd) is reconfirmed by using the experimental results of a 15-level inverter.

444 citations

Journal ArticleDOI
TL;DR: In this article, a new topology for sub-multilevel inverter is proposed and then series connection of the sub-multipliers is proposed as a generalized multi-level inverter.
Abstract: Application of multilevel inverters for higher power purposes in industries has become more popular. This is partly because of high-quality output waveform of multilevel inverters in comparison with two-level inverters. In this paper, initially a new topology for submultilevel inverter is proposed and then series connection of the submultilevel inverters is proposed as a generalized multilevel inverter. The proposed multilevel inverter uses reduced number of switching devices. Special attention has been paid to obtain optimal structures regarding different criteria such as number of switches, standing voltage on the switches, number of dc voltage sources, etc. The proposed multilevel inverter has been analyzed in both symmetric and asymmetric conditions. The validity of the proposed multilevel inverter is verified with both computer simulations using PSCAD/EMTDC software and laboratory prototype implementation.

411 citations


Cites background from "A Survey on Neutral-Point-Clamped I..."

  • ...However, a larger number of levels increase the number of devices that must be controlled and the control complexity [3]....

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References
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Journal ArticleDOI
TL;DR: The most important topologies like diode-clamped inverter (neutral-point clamped), capacitor-Clamped (flying capacitor), and cascaded multicell with separate DC sources are presented and the circuit topology options are presented.
Abstract: Multilevel inverter technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy control. This paper presents the most important topologies like diode-clamped inverter (neutral-point clamped), capacitor-clamped (flying capacitor), and cascaded multicell with separate DC sources. Emerging topologies like asymmetric hybrid cells and soft-switched multilevel inverters are also discussed. This paper also presents the most relevant control and modulation methods developed for this family of converters: multilevel sinusoidal pulsewidth modulation, multilevel selective harmonic elimination, and space-vector modulation. Special attention is dedicated to the latest and more relevant applications of these converters such as laminators, conveyor belts, and unified power-flow controllers. The need of an active front end at the input side for those inverters supplying regenerative loads is also discussed, and the circuit topology options are also presented. Finally, the peripherally developing areas such as high-voltage high-power devices and optical sensors and other opportunities for future development are addressed.

6,472 citations


"A Survey on Neutral-Point-Clamped I..." refers background in this paper

  • ...Another commutation introduced in [2] as type 2 takes place between one outer and one inner device....

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  • ...Highly popular are the voltage-source multilevel inverters, which can be divided into three categories, according to their topology: neutral point clamped (NPC), flying capacitor (FLC), and cascade H-bridge [1], [2]....

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01 Jan 1980
TL;DR: In this article, a neutral-point-clamped PWM inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed.
Abstract: A new neutral-point-clamped pulsewidth modulation (PWM) inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed. This inverter output contains less harmonic content as compared with that of a conventional type. Two inverters are compared analytically and experimentally. In addition, a new PWM technique suitable for an ac drive system is applied to this inverter. The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.

4,432 citations

Journal ArticleDOI
TL;DR: The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.
Abstract: A new neutral-point-clamped pulsewidth modulation (PWM) inverter composed of main switching devices which operate as switches for PWM and auxiliary switching devices to clamp the output terminal potential to the neutral point potential has been developed. This inverter output contains less harmonic content as compared with that of a conventional type. Two inverters are compared analytically and experimentally. In addition, a new PWM technique suitable for an ac drive system is applied to this inverter. The neutral-point-clamped PWM inverter adopting the new PWM technique shows an excellent drive system efficiency, including motor efficiency, and is appropriate for a wide-range variable-speed drive system.

4,328 citations


"A Survey on Neutral-Point-Clamped I..." refers background in this paper

  • ...1, the NPC inverter introduced 25 years ago is the most widely used in all types of industrial applications [3], [4], in the range of 2....

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Journal ArticleDOI
TL;DR: This paper covers the high-power voltage-source inverter and the most used multilevel-inverter topologies, including the neutral-point-clamped, cascaded H-bridge, and flying-capacitor converters.
Abstract: This paper presents a technology review of voltage-source-converter topologies for industrial medium-voltage drives. In this highly active area, different converter topologies and circuits have found their application in the market. This paper covers the high-power voltage-source inverter and the most used multilevel-inverter topologies, including the neutral-point-clamped, cascaded H-bridge, and flying-capacitor converters. This paper presents the operating principle of each topology and a review of the most relevant modulation methods, focused mainly on those used by industry. In addition, the latest advances and future trends of the technology are discussed. It is concluded that the topology and modulation-method selection are closely related to each particular application, leaving a space on the market for all the different solutions, depending on their unique features and limitations like power or voltage level, dynamic performance, reliability, costs, and other technical specifications.

2,254 citations


"A Survey on Neutral-Point-Clamped I..." refers background in this paper

  • ...It comprises two phase legs and is suitable for use in an H-bridge configuration....

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  • ...Highly popular are the voltage-source multilevel inverters, which can be divided into three categories, according to their topology: neutral point clamped (NPC), flying capacitor (FLC), and cascade H-bridge [1], [2]....

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  • ...[63] M. A. Perez, P. Cortes, and J. Rodriguez, “Predictive control algorithm technique for multilevel asymmetric cascaded H-bridge inverters,” IEEE Trans....

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  • ...Aside from the wellknown two-level VSC, there are 3L-NPC-VSCs [46], [47], four-level FLC VSCs [48], [49], multilevel series-connected H-bridge (SCHB) VSCs (e.g., five-level SCHB VSCs, seven- level SCHB VSCs, and nine-level SCHB VSCs) [50], [51], and five-level NPC H-Bridge VSCs....

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Journal ArticleDOI
TL;DR: The author provides a guideline and quick reference for the practicing engineer to decide which methods should be considered for an application of a given power level, switching frequency, and dynamic response.
Abstract: The author evaluates the state of the art in pulsewidth modulation for AC drives fed from three-phase voltage source inverters. Feedforward and feedback pulsewidth modulation schemes with relevance for industrial application are described and their respective merits and shortcomings are explained. Secondary effects such as the influence of load-current dependent switching time delay and transients in synchronized pulsewidth modulation schemes are discussed, and adequate compensation methods are presented. Recorded oscillograms illustrate the performance of the respective pulsewidth modulation principles. The author provides a guideline and quick reference for the practicing engineer to decide which methods should be considered for an application of a given power level, switching frequency, and dynamic response. >

1,250 citations


"A Survey on Neutral-Point-Clamped I..." refers background in this paper

  • ...The modulator must also detect the position of the reference vector to identify the closest vectors [33]....

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  • ...2) Space Vector Modulator [10]–[15], [33], [60]: The three-level phase inverter has 3(3) = 27 different switching states which generate different voltage vectors defined by...

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