Impedance networks cover the entire of electric power conversion from dc (converter, rectifier), ac (inverter), to phase and frequency conversion (ac-ac) in a wide range of applications. Various ...converter topologies have been reported in the literature to overcome the limitations and problems of the traditional voltage source, current source as well as various classical buck-boost, unidirectional, and bidirectional converter topologies. Proper implementation of the impedance-source network with appropriate switching configurations and topologies reduces the number of power conversion stages in the system power chain, which may improve the reliability and performance of the power system. The first part of this paper provides a comprehensive review of the various impedance-source-networks-based power converters and discusses the main topologies from an application point of view. This review paper is the first of its kind with the aim of providing a "one-stop" information source and a selection guide on impedance-source networks for power conversion for researchers, designers, and application engineers. A comprehensive review of various modeling, control, and modulation techniques for the impedance-source converters/inverters will be presented in Part II.
A-Source Impedance Network Siwakoti, Yam P.; Blaabjerg, Frede; Galigekere, Veda Prakash ...
IEEE transactions on power electronics,
12/2016, Letnik:
31, Številka:
12
Journal Article
Recenzirano
A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage ...gain. The network utilizes a minimal turns ratio compared to other magnetically coupled impedance source networks to attain a high voltage gain. In addition, the proposed converter draws a continuous current from the source, and hence it is suitable for many types of renewable energy sources. The derived network expressions and theoretical analysis are finally validated experimentally with an example single-switch 400-W dc-dc converter. For the closed-loop control design and stability assessment, a small signal model and its analysis of the proposed network are also presented in brief.
L'article décrit la conception et la mise en œuvre en temps réel d'une commande non linéaire appliquée à un système de conversion de l'énergie éolienne (SCEE). La commande backstepping a été mise en ...œuvre pour améliorer les performances du système de conversion éolienne basé sur un générateur synchrone à aimants permanents (PMSG) connecté au réseau. Deux convertisseurs statiques assurent la connexion au réseau et sont contrôlés par la modulation de largeur d'impulsion (MLI). L'algorithme de contrôle proposé assure un contrôle de vitesse adéquat pour extraire la puissance maximale. Une description détaillée des lois de contrôle du backstepping basées sur la technique de stabilité de Lyapunov a été exposée. Les résultats obtenus par l'application de cette approche ont clairement répondu aux exigences de robustesse et de suivi des références même dans des conditions de vent fluctuants, et ont confirmé l'efficacité d'un tel contrôle dans les modes de fonctionnement statique et dynamique.
We report losses from charging and discharging the parasitic output capacitor, <inline-formula> <tex-math notation="LaTeX">{\rm C}_{\rm OSS}</tex-math></inline-formula>, in Gallium Nitride (GaN) ...power devices with voltage ratings over 600 <inline-formula><tex-math notation="LaTeX">{\rm V}_{\rm DS}</tex-math></inline-formula> . These losses are of particular importance in soft-switched circuits used at MHz switching frequencies, where the output capacitance of the device is charged and discharged once per switching cycle during the device's off-time. This process is assumed lossless. We measure <inline-formula><tex-math notation="LaTeX">{\rm C}_{\rm OSS}</tex-math> </inline-formula> losses from 5-35 MHz sine, square, and Class-<inline-formula><tex-math notation="LaTeX"> \Phi _{2}</tex-math></inline-formula> waveshapes in enhancement-mode and cascode devices, and find that losses are present in all tested devices, equal or greater than conduction losses at MHz frequencies, and exponentially increasing with <inline-formula><tex-math notation="LaTeX">\mathbf{dV/dt}</tex-math></inline-formula>. The cascode device outperforms the e-mode devices under 300 V, but the e-mode devices are preferred above this operating voltage. Furthermore, we show that, within a device family, losses scale linearly with output energy storage. Packaging appears to have only a minor effect on these losses. Finally, we demonstrate 10 MHz, 200 W dc-dc converters with varying device configurations, showing that, even with constant circulating currents, moving to larger devices with lower <inline-formula><tex-math notation="LaTeX">{\rm R}_{\rm DS,ON}</tex-math> </inline-formula> actually degrades efficiency in certain applications due to <inline-formula> <tex-math notation="LaTeX">{\rm C}_{\rm OSS}</tex-math></inline-formula> losses. In the high-voltage, high-frequency range, these reported losses must be optimized simultaneously with conduction losses on a per-application basis.
Phase change materials (PCMs) are widely regarded as one of the most promising thermal energy storage technologies, owing to their outstanding latent heat storage density and controllable thermal ...storage/release characteristics. However, pure PCM usually has certain limitations in terms of electric‐, photo‐, and magnetic‐thermal conversion. In recent years, research on enhancing these properties through the addition of various fillers has garnered widespread attention. Herein, this paper elaborates on the modification of PCM for electric‐thermal, photo‐thermal, and magnetic‐thermal conversion, including their respective modification strategies, properties, and applications. Therein, a comparative analysis is conducted on the electric‐, photo‐, and magnetic‐thermal conversion efficiency of PCM with different fillers. Further, a summary and analysis are conducted on the addition of some fillers to PCM, which simultaneously improves the conversion performance of the two or three mentioned above, enabling multiple energy conversion. Finally, existing problems, solutions, and future development directions are put forward.
Pure phase change materials (PCMs) as thermal energy media often encounter limitations in electric‐thermal, photo‐thermal, and magnetic‐thermal conversions. There are various methods for modifying PCM in these areas, efficiency in these conversions varies with conditions, and incorporating fillers facilitates PCM to achieve multiple energy conversions, offering promising advancements in energy storage technologies.
Power-bidirectional converters are used to integrate energy storage with both dc and ac distribution grids. A modular bidirectional dc-dc converter system consisting of multiple dual-bridge series ...resonant converter (DBSRC) modules can be reconfigured to extend the system operating range. This paper proposes a modular three-phase ac-dc converter system by adding a line-frequency unfolder to series-connected outputs of two DBSRC modules. The DBSRC modules are controlled to output time-varying currents, which are then reconstructed into sinusoidal ac currents by the unfolder. Compared with a conventional two-stage system with a dc-dc converter and a two-level voltage-source inverter, the DBSRC-unfolder system has smaller dc-link capacitance, negligible unfolder switching loss, reduced line filter size, and faster dynamic response. The system operation and performance are verified on a 1-kW experimental prototype.
Car sa conversion tardive â la sociologie en 1967 était pour lui une façon de poursuivre, sur des bases nouvelles, les mėmes fins avec ďautres moyens !Au depart, rien ne prédestinait un prof de ...philosophie de khâgne â édifier, ex nihilo, une structure universitaire ďenseignement et de recherche en sociologie dans une ville qui n'avait jamais manifeste beaucoup ď intérét pour les sciences sociales, â ľexception notable ďAnge Guépin, au siede precedent.Il investit alors le monde académique de la sociologie avec la meme ardeur qu'il avait déployée pour imposer sa figure d'intellectuel au sein des instances du Parti communiste quinze ans plus tót: membre de la section sociologie du Comité consultatif des universités au moment des reformes universitaires d'aprés mai-juin 1968, il fit partie de plusieurs comités de redaction de revues de sciences sociales, notamment Ethnologie française.Le souci du peuple La fondation du Lersco et ľorientation des activités de recherche de ce nouveau departement de sociologie vers la connaissance empirique des conditions d'existence et de travail des ouvriers, leurs façons de vivre, de croire, de penser et de se distraire s'inscrivaient dans le droit fil des preoccupations initiales de Michel Verret et son souci du peuple.
Visible-light photocatalysis that can directly harvest energy from incoming solar energy offers a desirable way to solve energy and environment issues. , J. L. Gong and co-workers report the ...preparation of an efficient homotype Ag3PO sub(4)/BiVO sub(4) heterojunction photocatalyst via rational structure design. The Ag3PO sub(4) nanoparticles are preferentially deposited on the highlyactive BiVO sub(4) (040) facets via a surfactantmediated mechanism. The Ag3PO sub(4)/BiVO sub(4) photocatalyst shows high charge separation efficiency as well as an enhanced visiblelight response and thus possesses excellent visible light photocatalytic activity. The capability of synthesizing a highly visible light active and stable heterojunction photocatalyst is useful for other solar conversion applications, such as PEC water splitting, dye-sensitized solar cells and photovoltaic devices.
Model predictive control (MPC) is a very attractive solution for controlling power electronic converters. The aim of this paper is to present and discuss the latest developments in MPC for power ...converters and drives, describing the current state of this control strategy and analyzing the new trends and challenges it presents when applied to power electronic systems. The paper revisits the operating principle of MPC and identifies three key elements in the MPC strategies, namely the prediction model, the cost function, and the optimization algorithm. This paper summarizes the most recent research concerning these elements, providing details about the different solutions proposed by the academic and industrial communities.
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