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María Prats

Bio: María Prats is an academic researcher from University of Seville. The author has contributed to research in topics: Converters & Space vector modulation. The author has an hindex of 17, co-authored 51 publications receiving 3619 citations.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the most relevant characteristics of multilevel converters, to motivate possible solutions, and to show that energy companies have to bet on these converters as a good solution compared with classic two-level converters.
Abstract: This work is devoted to review and analyze the most relevant characteristics of multilevel converters, to motivate possible solutions, and to show that we are in a decisive instant in which energy companies have to bet on these converters as a good solution compared with classic two-level converters. This article presents a brief overview of the actual applications of multilevel converters and provides an introduction of the modeling techniques and the most common modulation strategies. It also addresses the operational and technological issues.

1,847 citations

Journal ArticleDOI
20 Oct 2009
TL;DR: This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.
Abstract: Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.

949 citations

Journal ArticleDOI
TL;DR: A complete analytical strategy to model a back-to-back three-level converter is described and the model pays special attention to the unbalance in the capacitors' voltage of three- level converters, including the dynamics of the capacitor's voltage.
Abstract: Three-level converters are becoming a realistic alternative to the conventional converters in high-power wind-energy applications. In this paper, a complete analytical strategy to model a back-to-back three-level converter is described. This tool permits us to adapt the control strategy to the specific application. Moreover, the model of different loads can be incorporated to the overall model. Both control strategy and load models are included in the complete system model. The proposed model pays special attention to the unbalance in the capacitors' voltage of three-level converters, including the dynamics of the capacitors' voltage. In order to validate the model and the control strategy proposed in this paper, a 3-MW three-level back-to-back power converter used as a power conditioning system of a variable speed wind turbine has been simulated. Finally, the described strategy has been implemented in a 50-kVA scalable prototype as well, providing a satisfactory performance

230 citations

Journal ArticleDOI
TL;DR: In this article, a space vector modulation algorithm using abc coordinates (the phase voltages) avoiding the /spl alpha/spl beta/spl gamma/ transformation is presented. But the algorithm is much simpler and more intuitive than in the traditional binary space vector representation.
Abstract: Four-leg inverters have been selected as one of the preferred power converter topologies for applications that require a precise control of neutral current, like active filters. The main advantage of this topology lies in an extended range for the zero sequence voltages and currents. However, the addition of a fourth leg extends the space vectors from two to three dimensions, making the selection of the modulation vectors more complex. Most of the algorithms that deal with this problem require an /spl alpha//spl beta//spl gamma/ transformation. This paper presents a new space vector modulation algorithm using abc coordinates (the phase voltages) avoiding the /spl alpha//spl beta//spl gamma/ transformation. Thanks to the use of abc coordinates, the algorithm is much simpler and more intuitive than in /spl alpha//spl beta//spl gamma/ representation, drastically reducing the complexity of modulation algorithm and the computational load associated to it.

135 citations

Journal ArticleDOI
TL;DR: La prevalencia del burnout es mayor en Espana y Argentina y los profesionales that mas lo padecen son los medicos.
Abstract: Fundamento: La aparicion del sindrome de burnout se relaciona con factores ambientales, culturales y personales. Los objetivos de este estudio son comparar la prevalencia de burnout entre profesionales sanitarios de paises de habla hispana y explorar su asociacion con las caracteristicas sociodemograficas y profesionales de los trabajadores y con sus percepciones. Metodos: Se ha estudiado el sindrome de burnout en 11.530 profesionales de la salud de habla hispana (51% varones, edad media de 41,7 anos). Se utilizo el Maslach Burnout Inventory y un cuestionario de elaboracion propia via online desde el portal sanitario Intramed. El periodo de estudio fue desde diciembre del 2006 hasta septiembre del 2007. Las asociaciones entre variables se estudiaron mediante pruebas de regresion logistica. Resultados: La prevalencia de burnout en los profesionales residentes en Espana fue de 14,9%, del 14,4% en Argentina, y del 7,9% en Uruguay. Los profesionales de Mexico, Ecuador, Peru, Colombia, Guatemala y El Salvador presentaron prevalencias entre 2,5% y 5,9%. Por profesiones, Medicina tuvo una prevalencia del 12,1%, Enfermeria del 7,2%, y Odontologia, Psicologia y Nutricion tuvieron cifras inferiores al 6%. Entre los medicos el burnout predominaba en los que trabajaban en urgencias (17%) e internistas (15,5%), mientras que anestesistas y dermatologos tuvieron las prevalencias mas bajas (5% y 5,3% respectivamente). Fueron variables protectoras la mayor edad (OR=0,96), tener hijos (OR=0,93), la percepcion de sentirse valorado (OR=0,53), el optimismo (OR=0,80), la satisfaccion profesional (OR=0,80) y la valoracion economica (OR=0,91). Conclusiones: La prevalencia del burnout es mayor en Espana y Argentina y los profesionales que mas lo padecen son los medicos. La edad, tener hijos, la percepcion de sentirse valorado, el optimismo, la satisfaccion laboral y la valoracion economica, son variables protectoras de burnout.

127 citations


Cited by
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Journal ArticleDOI
TL;DR: New trends in power electronics for the integration of wind and photovoltaic (PV) power generators are presented and a review of the appropriate storage-system technology used for the Integration of intermittent renewable energy sources is introduced.
Abstract: The use of distributed energy resources is increasingly being pursued as a supplement and an alternative to large conventional central power stations. The specification of a power-electronic interface is subject to requirements related not only to the renewable energy source itself but also to its effects on the power-system operation, especially where the intermittent energy source constitutes a significant part of the total system capacity. In this paper, new trends in power electronics for the integration of wind and photovoltaic (PV) power generators are presented. A review of the appropriate storage-system technology used for the integration of intermittent renewable energy sources is also introduced. Discussions about common and future trends in renewable energy systems based on reliability and maturity of each technology are presented

3,799 citations

Journal ArticleDOI
TL;DR: This paper first presents a brief overview of well-established multilevel converters strongly oriented to their current state in industrial applications to then center the discussion on the new converters that have made their way into the industry.
Abstract: Multilevel converters have been under research and development for more than three decades and have found successful industrial application. However, this is still a technology under development, and many new contributions and new commercial topologies have been reported in the last few years. The aim of this paper is to group and review these recent contributions, in order to establish the current state of the art and trends of the technology, to provide readers with a comprehensive and insightful review of where multilevel converter technology stands and is heading. This paper first presents a brief overview of well-established multilevel converters strongly oriented to their current state in industrial applications to then center the discussion on the new converters that have made their way into the industry. In addition, new promising topologies are discussed. Recent advances made in modulation and control of multilevel converters are also addressed. A great part of this paper is devoted to show nontraditional applications powered by multilevel converters and how multilevel converters are becoming an enabling technology in many industrial sectors. Finally, some future trends and challenges in the further development of this technology are discussed to motivate future contributions that address open problems and explore new possibilities.

3,415 citations

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

Journal ArticleDOI
TL;DR: A survey of different topologies, control strategies and modulation techniques used by cascaded multilevel inverters in the medium-voltage inverter market is presented.
Abstract: Cascaded multilevel inverters synthesize a medium-voltage output based on a series connection of power cells which use standard low-voltage component configurations. This characteristic allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. Due to these features, the cascaded multilevel inverter has been recognized as an important alternative in the medium-voltage inverter market. This paper presents a survey of different topologies, control strategies and modulation techniques used by these inverters. Regenerative and advanced topologies are also discussed. Applications where the mentioned features play a key role are shown. Finally, future developments are addressed.

2,111 citations

Journal ArticleDOI
TL;DR: In this paper, the most relevant characteristics of multilevel converters, to motivate possible solutions, and to show that energy companies have to bet on these converters as a good solution compared with classic two-level converters.
Abstract: This work is devoted to review and analyze the most relevant characteristics of multilevel converters, to motivate possible solutions, and to show that we are in a decisive instant in which energy companies have to bet on these converters as a good solution compared with classic two-level converters. This article presents a brief overview of the actual applications of multilevel converters and provides an introduction of the modeling techniques and the most common modulation strategies. It also addresses the operational and technological issues.

1,847 citations