5,895 research outputs found
LC compensators for power factor correction of nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEA method is presented for finding the optimum fixed LC compensator for power factor correction of nonlinear loads where both source voltage and load current harmonics are present. The LC combination is selected because pure capacitive capacitors alone would not sufficiently correct the power factor. Optimization minimizes the transmission loss, maximizes the power factor, and maximizes the efficiency. The performance of the obtained compensator is discussed by means of numerical examples
LC compensators based on transmission loss minimization for nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEThis paper presents a method employing the penalty function search algorithm to determine the LC compensator value for the optimal power factor correction in nonsinusoidal systems. The objective of the proposed method is to minimize the transmission loss while the power factor and efficiency are taken as constraints and utilized in order to solve the multiobjective optimization problem by transforming it into a single objective one. Examples show that the load nonlinearity can have a significant impact on optimal compensator sizes
Cost-effective applications of power factor correction for nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2005 IEEEThe objective of this paper is to propose a new approach for designing passive LC compensators by using the penalty function method as an optimization tool. The performance of the cost-effective passive LC compensator for a constant load depends on the appropriate inductor and capacitor selection. Several design methods are reviewed and a novel design methodology is proposed in this paper. By using the proposed method, the designer can quickly find appropriate parameter values to meet the desired circuit performance. Simulated results show that an appropriate combination of the inductor and capacitor selected by the proposed method can meet the desired power-quality requirement. Different cases of design examples are shown in this paper to verify the performance of the proposed design methodology
A 155W −95.6 dB THD+N GaN-based Class-D Audio Amplifier With LC Filter Nonlinearity Compensation
No full textSilicon MOSFETs-based medium-power (< 50W) Class-D amplifiers (CDAs) switching in the MHz range have gained popularity in recent years, which achieves better linearity thanks to a higher loop gain in the audio band while enabling the use of LC filters with higher cut-off frequencies. However, for high-power (>100 W) CDAs, such switching frequency and high load current could lead to significant power loss. Furthermore, in the presence of a large current and voltage applied to the load, the linearity of the system can quickly degrade due to LC filter component voltage/current dependency. Without any LC filter nonlinearity compensation technique, LC components with high voltage/current rating must be used to reach high system linearity, which are often expensive and bulky. This paper presents a CDA using a GaN-based output stage to achieve high switching frequency and good efficiency simultaneously, and an integrated controller implemented in a 180nm CMOS technology to compensate for the LC filter nonlinearity. Switching at 1.8 MHz, the CDA can deliver a maximum of 155W from a 50V supply into a load with a peak efficiency of 91.7%. It achieves a peak THD+N of −95.6 dB (0.0017%) while allowing the use of cheaper and smaller nonlinear LC components.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and MaterialsMicroelectronic
A - 121.5-dB THD Class-D Audio Amplifier With 49-dB LC Filter Nonlinearity Suppression
No full textClass-D audio amplifiers produce electromagnetic interference (EMI), which often needs to be suppressed by an external LC filter. However, due to component nonlinearity, this filter can itself cause significant distortion. This article presents a class-D amplifier that suppresses LC filter nonlinearity by 49 dB and is robust to ±30% variations in its cutoff frequency. This is achieved by a dual-loop architecture, in which an inner loop provides stability, while an outer loop provides the high gain needed to suppress the LC filter and output-stage nonlinearity. A prototype, implemented in a 180-nm BCD process, achieves -121.5-dB total harmonic distortion (THD) and -107.1-dB THD+N, which is maintained to within 3 dB even as the LC filter cutoff frequency is varied from 62 to 106 kHz. It can deliver a maximum of 21 W into a 4-Ω load with 87% efficiency and 12 W into an 8-Ω load with 91% efficiency, measured at 10% THD. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
Le Corbusier y la fotografía. De la re-producción a la escritura de la villa Church, Ville-d'Avray
No full text[ES] El artículo analiza el uso que Le Corbusier hace de la fotografía para la publicación y difusión de su obra en las décadas de 1920 y 1930, proponiendo la Ville D’Avray como ejemplo paradigmático. Apoyándonos en la interpretación de la fotografía surrealista como signo y escritura realizada por Rosalind Krauss (1981), proponemos una lectura alternativa a la realizada por Colomina (1988) del uso de la fotografía en la edición y publicación. Entendiendo la fotografía como soporte material y repositorio de información –una suerte de archivo visual preparado para ser manejado como evidencia documental pero también como instrumento autónomo en la construcción de nuevos significados, se describe una estrategia de edición de las fotografías caracterizada por la autonomía con respecto a la realidad material y su manipulación con procedimientos próximos al Surrealismo. Desde este punto de vista crítico, la fotografía sería una técnica para producir no ya imágenes sino ‘signos’ cuya función es ensanchar y ampliar nuestro entendimiento de la realidad y de sus potencialidades.[FR] L'article analyse l'usage que fait Le Corbusier de la photographie dans la publication et la diffusion de son oeuvre au cours des années 1920 et 1930, en prenant comme exemple paradigmatique de la Ville Church, Ville-d’Avray. Pour ce faire, nous proposons une lecture alternative à celle réalisée, de ce moyen, par Colomina (1988), en nous appuyant sur l'interpretation de la photographie surréaliste, effectuée par Rosalind Krauss (1981), comme signe et lecture. Concevant la photographie comme signe et lecture. Concevant la photographie come support matériel et lieu de dépôt de l'information - une sorte d’archive visuel prêt à être manipulé comme évidence documentaire, voire comme instrument autonome, dans la construction de nouveux signifiants -, nous décrivons une stratégie dans l'édition des photographies qui se caractérise par son autonomie au regard du référent matériel ainsi que par sa manipulation moyennant les procédés partagés avec le Surréalisme. De ce point de vue critique, la photographie serait une technique ayant pour but de produire non pas des images mais des 'signes' dont la fonction est celle d'élargir et d'amplifier notre compréhension de la réalité et de l’architecture comme construction de cette dernière.[EN] The article proposes an analysis of Le Corbusier’s use of photography during the 1920s and 1930s for the publication and dissemination of his work, specifically looking at the images of the villa Church, Ville-d'Avray, as a paradigmatic example and a case study. Relying on the interpretation of surrealist photography as sign and writing carried out by Rosalind Krauss (1981), we make an argument for an alternative understanding of the use and content of this medium. If the photographic medium is considered as a kind of material support and a repository of information - a sort of visual archive prepared to be used as documentary evidence but also as an autonomous instrument in the construction of new meanings -, the autonomous editing with regard to its material referent and its manipulation with procedures shared with Surrealism became significant. From this critical stand point, photography would be a technique to produce not images but ‘signs’, capable of enlarging our understanding of reality and of architecture.Escuela Técnica Superior de Arquitectura Universidad Politécnica de MadridRojo De Castro, L. (2020). Le Corbusier y la fotografía. De la re-producción a la escritura de la villa Church, Ville-d'Avray. LC. Revue de recherches sur Le Corbusier. 1(2):62-75. https://doi.org/10.4995/lc.2020.13809OJS62751
Multichannel LC ADC: to Record Atrial Electrograms
No full textBiosignals such as electoencephalogram (EEG), electrocorticogram (ECoG), atrial electrogram (AEG) etc. are being recorded from multiple channels simultaneously to improve the spatial resolution of the signals. Conventional multichannel synchronous Analog-to-Digital Converters (ADCs) are used to convert the analog continuous time signals into discrete digital values. Several biosignals have a sparsity in time domain as they have fast-rising peaks in between periods of low activity. Use of conventional synchronous ADCs for conversion of such signals is not an efficient approach as their operation is constant, irrespectiveof the activity of the input signals. Asynchronous ADCs such as level-crossing (LC) ADCs exploit the sparsity of biosignals and thus their operation is activity-dependent. However, multichannel configurations of LC ADCs do not yet exist. This problem is investigated in this work and a new ADC architecture is presented that can combine synchronous sampling with level-crossing quantisation method while converting input signals from several channels simultaneously. The synchronous LC ADC presented in this work achieves 3.37 times reduction in quantisation steps and 6 times reduction in number of output bits generated during conversion of AEG signals as compared to conventional synchronous ADCs. The problem in existing LC ADCs of data overhead in adaptive resolution technique is solved through a novel method named split resolution technique which is also presented in this work.Electrical Engineerin
El “Autorum elenchus” de Francisco de Castro: lecturas retóricas de un jesuita del s. XVII
No full textIn Córdoba, 1611 and Seville, 1625 the Spanish Jesuit Francisco de Castro published a rhetoric handbook entitled De arte rhetorica dialogi quatuor, at the end of which he included a list of specialized works in rhetoric (“Autorum elenchus”), which is a valuable document to further our knowledge of Jesuit bibliographical sources. This feature, uncommon in similar books published at that time in Spain, was preceded by a brief statement where Castro declared that the elenchus contains the books that he had seen and read from cover to cover and from many of which he had learnt a great deal and taken information for composing his treatise. This paper offers the modern edition and study of the above mentioned catalogue and puts forward the idea that the initial statement should not be taken literally, since the elenchus seems to contain references to authors and works which were probably only indirectly known of by the Jesuit. The aim of including these secondary references, which were mentioned in other catalogues as important readings for an accomplished rhetorician, would have been to strengthen Castro’s prestige, as well as the authority of his rhetoric
Practical considerations regarding power factor for nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEThe choice of LC compensator may be constrained by the availability of manufacturers units. To account for this, the capacitor values are chosen from among standard values and for each value the transmission losses is minimized, or power factor is maximized, or transmission efficiency is maximized. The global minimum or maximum is obtained by scanning all local minims or maxims. The performance of the obtained compensator is discussed by means of numerical examples
A -91 dB THD+N Resistor-Less Class-D Piezoelectric Speaker Driver Using a Dual Voltage/ Current Feedback for LC Resonance Damping
No full textPiezoelectric speakers are gaining popularity on account of their improving form-factor and audio quality, making them a good fit for many audio applications such as in televisions, laptops, etc. Such speakers can be modelled as a large capacitive load, and so are typically driven by a Class-AB amplifier via a series resistor that ensures driver stability, and limits load current, but wastes power [1], [2]. In [3], the Class-AB amplifier is replaced by a more power-efficient Class-D amplifier (CDA) in series with an additional inductor. However, a series resistor is still required to damp the resulting LC resonant circuit, which could otherwise draw excessive currents when excited by large-signal distortion (e.g. clipping) harmonics around the LC resonance frequency. Alternatively, by using a feed-forward architecture based on LC filter diagnostics to limit overshoot currents, the series resistor can be replaced by a second inductor, at the expense of increased system complexity and cost [4].Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
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