Letteratura scientifica selezionata sul tema "PowerElectronics"

To prepare for the future high penetration level of renewable energy sources, the power grid’s technical boundaries/constraints for the correct operation of powerelectronics interfaced devices need to be further examined and defined. This paper investigates the challenge of integrating Voltage Source Converters (VSC) into low inertia power grids, where the system frequency can vary rapidly due to the low kinetic energy buffer available, which used to be provided by the rotational inertia of synchronous generators. The impact of rate of change of frequency (ROCOF) on the PLL dynamics and its subsequent influence on the VSC power stage output is explained. The Bonaire island network is presented as case study. The performance of the VSC is analyzed under a fast ROCOF event, which is triggered by a short circuit fault. A down-scaled experiment is used to validate the Bonaire island network simulation results. It shows that the phase angle error measured by the synchronous-reference frame phase-locked loop (SRF-PLL) is proportional to the slope of the ROCOF and inversely proportional to its controller integral gain constant.

Model based predictive control is a new promising control method in the field of powerelectronics and electrical drives. The main advantages of MPC are simplicity and intuitiveness of thecontrol method. Constraints and nonlinearities of the system can easily be included, which makes thelinearisation of the system unnecessary. By using MPC it is possible to avoid the cascaded structureof common linear control methods and to gain a fast dynamic performance. A disadvantage is theneed to calculate the optimal actuating variable multiple times in every single sampling cycle leadsto a huge requirement of computational power. So far the computational requirement was the greatestbarrier for the practical application of model based predictive control in the field of power electronicsand electrical drive systems. In addition the small time constants of fractional horse power drivescomplicate the application of predictive control algorithms. In this paper, the feasibility of hardwareimplementation of a cost function based Finite Control Set MPC (FCS-MPC) algorithm for directspeed control of fractional horse power drives is explored. The cost function allows to address variouscontrol goals like dynamics of transitions and energy efficiency – an advantage linear conventionalcontrol methods cannot offer. Hitherto there are very few publications for direct predictive speed. Thepresented approach for direct predictive speed control includes a finite number of possible switchingstates of the converter. This considers the discrete nature of power converters and avoids the need formodulation. The basic principle of the control method is presented and the performance is demonstratedby simulations and experimental results for an industrial brushed type DC-motor.

This research aims to advance wireless power transfer (WPT) technology, focusing on increasing efficiency and transmission distance between the sending and receiving coils. The paper will explore the utilize of advanced powerelectronic converters for converting direct current to alternating current with maximum power transfer, this assessment was conducted on three distinct categories of inverters, namely classE, class-D, and H-bridge, in order to establish a comparison among them based on the identical parameters of the system. After formulating the proposed system, a simulation using matlab has been conducted for distances that vary across three variables. From the outcomes of this simulation, it has been determined that the class-E inverter exhibits the highest level of efficiency and power transfer in relation to the suggested battery charging system. Key words. Wireless power transfer (WPT), Inductive coupling wireless power transfer (ICWPT), electric vehicle (EV).

La technologie photovoltaïque (PV) nécessite une conversion d'énergie à haut rendement afin d'atteindre un prix acceptable par kWh produit. En effet, le coût des convertisseurs de puissance n'est pas négligeable dans l'installation et représente généralement 6 à 9 % du coût total de l'installation, selon le type d'installation (à l'échelle industrielle, commerciale ou résidentielle). Ce travail utilise l'optimisation de la conception d'un convertisseur d'électronique de puissance pour atteindre le meilleur coût de l'énergie dans une application photovoltaïque. La méthodologie utilise des modèles détaillés des composants actifs et passifs de l'électronique de puissance pour déterminer le coût et les performances d'un convertisseur statique en faisant le lien avec les contraintes système. L'algorithme déterministe utilisé pour le dimensionnement du convertisseur permet de prendre en compte un grand nombre de variables et de contraintes. La méthodologie, les modèles et quelques illustrations des résultats sont fournis dans cette thèse.La conception des filtres CEM est également un facteur critique dans la détermination du coût total d'un système d'électronique de puissance et doit être prise en compte dans le processus de conception. Dans la deuxième partie de la thèse, cette partie est abordée, en considérant que ces filtres seront optimisés après l'optimisation du convertisseur. Tout d'abord, les filtres CEM pour un onduleur photovoltaïque triphasé connecté au réseau, composé de deux convertisseurs en cascade (un convertisseur boost et d'un onduleur triphasé), sont conçus à partir d'une modélisation fréquentielle. Cette modélisation est validée par la simulation et l'expérience. Ensuite, en utilisant la même description de modèle que celle proposée dans la première partie, la stratégie d'optimisation modifie les paramètres technologiques des dispositifs, évalue les valeurs fonctionnelles des éléments de filtrage et détermine le spectre CEM sur le RSIL. L'objectif est de trouver une conception optimale des filtres CEM en estimant le bruit sur les côtés DC et AC simultanément. D'autres recherches ont été menées sur les convertisseurs multiniveaux qui sont largement utilisés dans les applications d'énergie renouvelable afin de réduire le volume des composants passifs. L'objectif est de trouver une conception optimale des filtres CEM en estimant les perturbations simultanément en entrée et en sortie. Un processus de modélisation générique, adapté à n'importe quel nombre de niveaux, est appliqué à un convertisseur boost à capacités flottantes à trois niveaux à titre d'illustration. Le modèle est développé et validé sur un prototype expérimental. Ensuite, les filtres sont conçus par un processus d'optimisation et validés par des mesures. Enfin, une analyse de sensibilité sur l'impact du nombre de niveaux et de la fréquence de commutation est réalisée
Photovoltaic (PV) technology requires a high-efficiency power conversion in order to achieve an acceptable price per produced kWh. Indeed, the cost of power converters is not negligible in the installation and usually accounts for about 6 to 9 percent of overall installation costs depending on the type of installation (utility scale, commercial scale, and residential scale). This work uses design optimization of a power electronics converter to achieve the best levelized cost of energy in a PV application. The methodology uses detailed models of power electronics’ active and passive components to determine the cost and performances of the solid-state energy conversion and connect them to the system-level vision. The deterministic algorithm used for converter sizing allows taking into account a large number of variables and constraints. Methodology, models, and some illustrations of the results are provided in this dissertation. The design of EMI filters is also a critical factor in determining the total cost of a power electronics system and should be taken into account in the design process. In the second part of thesis, this part is addressed, considering that these filters would be optimized after converter optimization. Firstly, the EMI filters for a grid-connected three-phase photovoltaic inverter, composed of two cascaded converters, a boost and a three-phase inverter are designed based on the frequency model. The methodology uses the frequency modeling approach, which has been validated in simulation and experiment. Then, using the same model description as the one proposed in the first part, the optimization strategy modifies the technological parameters of the devices, assesses the functional values of the filter elements, and determines the EMC spectrum on LISN. The objective is to find an optimal EMI filters design by estimating the EMI noise on the DC and AC sides simultaneously. Further research has been conducted on multi-level converters which have been widely used in renewable energy (RE) applications to reduce the volume of the passive components used in conventional converters. The objective is to find optimal EMI filters design by estimating the EMI noise on the input and output sides simultaneously. A generic modeling process, suitable for any number of levels, is applied to a three-level flying capacitor boost converter for illustration. The model is developed and validated on an experimental prototype. Then, the filters are designed by an optimization process and validated by measurement. Finally, a sensitivity analysis on the impact of the number of levels and the switching frequency is performed