3,383 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
Widely tunable band-pass ΣΔ ADCs: Modulators and decimators
No full textIn recent years, the increase in the number of wireless networks has motivated the research in Software Defined Radios (SDRs). SDRs are expected to directly convert Radio-Frequency (RF) signals to the digital domain, facilitating software-based signal processing. In the open literature it has been presented that LC-based Band-Pass Continuous-Time ΣΔ Modulators (BP CT-ΣΔM) can be used for the implementation of RF-to-digital converters. However, most of reported LC-based BP CT-ΣΔMs have used a fixed center or notch frequency, limiting the covered RF signals range
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
L'expérience formatrice de Le Corbusier à Vienne. 1907-1908
No full text[EN] Le Corbusier lived in Vienna between the months of November 1907 and March 1908. During that period, he moved away from the romantic, but pessimistic and conservative thought of John Ruskin, to get closer to the liberal and optimistic ideas of late German Romanticism. Ruskin proclaimed the renunciation of progress and advocated in defense of the cultural values ??of the medieval past. The Germans Gottfried Semper and Richard Wagner, on the other hand, fought against conventions and looked to the future
In the works of Wagner and other late Romantic composers, Le Corbusier was able to appreciate the characteristic artistic spirit of that period. After his experience in Austria and later in Germany, his artistic ideals came close to Semper's thought, even though it is likely that he never read his books, to a greater extent than Ruskin's, whom he did study in his youth.[ES] Le Corbusier residió en Viena entre los meses de noviembre de 1907 y marzo de 1908. Durante aquel periodo se alejó del pensamiento romántico, pero pesimista y conservador de John Ruskin, para acercarse a los designios liberales y optimistas que sellaron la última fase del Romanticismo alemán. Ruskin proclamaba la renuncia al progreso y abogaba en defensa de los valores culturales del pasado medieval. Los germanos Gottfried Semper y Richard Wagner afirmaban, por otro lado, la lucha contra las convenciones y posaban la mirada en el futuro, con optimismo y gran admiración por la tradición clásica helénica.
En la obra de Wagner y otros compositores del Romanticismo tardío, Le Corbusier pudo apreciar el espíritu artístico característico de dicho período. Tras su experiencia en Austria y posteriormente en Alemania, sus ideales artísticosse acercaron al pensamiento de Semper, pese a que es probable que no lo leyera nunca, en mayor medida que al de Ruskin, a quién si leyó en su juventud[1].
[1] José Miguel Mantilla; Untangling the Threads of Gottfried Semper's Legacy in Le Corbusier's Formative Years. Journal of the Society of Architectural Historians 1 June 2020; 79 (2): 192 201. doi: https://doi.org/10.1525/jsah.2020.79.2.192[FR] Le Corbusier vécut à Vienne entre les mois de novembre 1907 et mars 1908. Pendant cette période, il s'éloigna de la pensée romantique, mais pessimiste et conservatrice de John Ruskin, pour se rapprocher des conceptions libérales et optimistes du Romantisme allemand tardif. Ruskin a proclamé le renoncement au progrès et prôné la défense des valeurs culturelles du passé médiéval. Les Allemands Gottfried Semper et Richard Wagner, quant à eux, affirment la lutte contre les conventions et envisagent l'avenir avec optimisme, à partir de l'observation du passé classique hellénistique.
Dans l' uvre de Wagner et d'autres compositeurs romantiques, Le Corbusier a pu apprécier l'esprit artistique caractéristique de cette période. Après son expérience en Autriche puis en Allemagne, ses idéaux artistiques se sont rapprochés de la pensée de Semper (même s'il est probable qu'il n'ait jamais lu son uvre) plus que de celle de Ruskin qu il a étudiée dans sa jeunesse.Mantilla Salgado, JM. (2023). La experiencia formativa de Le Corbusier en Viena. 1907-1908. LC. Revue de recherches sur Le Corbusier. (8):102-117. https://doi.org/10.4995/lc.2023.19865OJS1021178Brooks, Harold Allen. 1997. Le Corbusier's formative years: Charles-Edouard Jeanneret at La Chaux-de-Fonds. Chicago: University of Chicago Press.Le Corbusier. 2011. Correspondance, Lettres a sa Famille 1900-1925. París: Infolio éditions.Nietzsche, Friedrich. 2003. Escritos sobre Wagner. Madrid: Biblioteca Nueva, S. L.Rostand, Edmond. 2018. Cyrano de Bergerac. Madrid: Edimat Libros.Curtis, William J. R. 2015. Le Corbusier: Ideas and Forms. London: Phaidon Press Limited .Turner, Paul V. 1987. La formation de Le Corbusier. Idealisme et Mouvement moderne. Éditions Macula.Schuré, Edouard. 1900. Souvenirs sur Richard Wagner. La première de Tristan et Iseul. Paris: Perrin et Cie, Libraires Éditeurs.Schuré, Edouard. 1921. Les Grands Initiés. Esquisse de L'Histoire Secrète des Religions. Paris: Librairie académique Perrin et Cie.Semper, Gottfried. 2014. Escritos fundamentales de Gottfried Semper. Editado por Antonio Armesto Aira. Traducido por Manuel García Roig. Barcelona: Fundación Arquia.Wagner, Richard. 2000. La obra de arte del futuro. Valencia: Universitat de València.Corbusier, Le, y L'Eplattenier. 2006. Le Corbusier - Lettres à Charles L'Eplattenier. Paris: Éditions du Linteau et ADAGP pour la Fondation Le Corbusier.Le Corbusier. 1925. L'Art décoratif d'aujourd'hui. Paris: Éditions G. Grès et Cie.Ruskin, John. 2006. La Biblia de Amiens. Madrid: Abada Editores.Dumont, Marie-Jeanne. 2014. Le Corbusier - William Ritter. Correspondance Croisée 1910 -1955. Lettres à ses maîtres III. Paris: Éditions du Linteau, Fondation Le Corbusier, Archives litteraires suisses
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
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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