1,720,985 research outputs found
Dynamic modeling and optimal control for hybrid electric vehicle drivetrain
No full textIn this paper, the series-parallel drivetrain architecture present in Hybrid Electric Vehicles is studied and modeled in detail using Matlab/Simulink. The system is composed of two permanent magnet synchronous machines in addition to the internal combustion engine all mechanically combined using a power split device. The novelty of this model is to use exclusively basic Simulink blocks resulting in a less execution time especially advantageous during implementation. Furthermore, the new modeling approach is focused on optimal control of both engine and electric machines in wide speed region. The obtained simulation results are proving the accuracy of the simpler dynamic model and the efficiency of its control
Asymmetric Mode Control of MMC to Suppress Capacitor Voltage Ripples in Low-Frequency, Low-Voltage Conditions
No full textThis paper proposes an asymmetric mode control for a modular multilevel converter (MMC) operating at low-frequency and low-output-voltage conditions. Differently from conventional symmetric operations, affected by large capacitor voltage ripples caused by the large dc-link voltage, with the proposed asymmetric mode MMC operations, one arm does not produce output current and applies the major dc-link voltage, whereas the other arm sustains almost all output current with low dc-link voltage. Variations of the power level in arms remain bounded and the MMC does not need any other power exchange technique such as high-frequency or harmonic current injection in a low-frequency/low-voltage condition to suppress the capacitor voltage ripple. The asymmetric control realization, and arm energy regulation and its optimization are presented in detail. Experimental and simulation results show that the proposed method is suitable for motor drives operating under 20 Hz
Position Sensorless Permanent Magnet Synchronous Machine Drives: A Review
No full textOwing to the competitive advantages of cost reduction, system downsizing, and reliability enhancement, position sensorless control methods for permanent magnet synchronous machine drives have drawn increasing attention from academia to industrial applications. In this article, a survey of the major sensorless control techniques for a wide speed range from low to high speeds is presented. The different high frequency signal injection schemes, fundamental pulsewidth modulation excitation methods, and model-based sensorless control are displayed and compared, which is able to facilitate the sensorless control implementation.Fil: Wang, Gaolin. Harbin Institute of Technology; República de ChinaFil: Valla, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Solsona, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentin
Position sensorless AC motor drives
No full textThe papers in this special section focus on position sensorless AC motor drives. Rotor position and speed information is crucial for highperformance ac machine drives. Since the merits, such as cost reduction, system downsizing, and reliability enhancement can be achieved through position sensorless (also noted as self-sensing) control, many techniques for a wide range of rotor speed from standstill to high speed have been developed in the last few decades. Sensorless control techniques have been commercialized and widely used in industrial applications. However, there are still a large number of unresolved issues, which limit the applications of sensorless ac motor drives. The extreme speed sensorless control is still a big challenge. Besides, the robustness of the position estimation scheme against timevarying parameters, inverter nonlinearities, multisaliency, etc., also aggravate the control performance in some applications. This Special Section on “Position Sensorless AC Motor Drives” in the IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS provides an insight into some of the newly emerging challenges and potential solutions to overcome those aforementioned issues. It will be timely and of great interest for all those working in this area and, of course, for industry.Fil: Valla, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales. Universidad Nacional de La Plata. Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales; ArgentinaFil: Wang, Gaolin. Harbin Institute of Technology; ChinaFil: Solsona, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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