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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Optimisation du routage d'un filtre CEM / EMC filter layout optimization

Oliveira, Thomas de 18 July 2012 (has links)
La tendance de l'intégration en électronique de puissance accentue naturellement les effets électromagnétiques parasites. Tout système d'énergie électrique devient alors source de perturbations EM aussi bien conduites que rayonnées. Mais dans le cadre de ces travaux, nous nous sommes focalisé sur l'organe de filtrage des perturbations conduites : le filtre CEM. En haute fréquence, il s'avère que ce type de système voit son comportement dégradé en raison des différents phénomènes parasites apparaissant au sein même du dispositif. Seuls les aspects magnétiques du problème ont néanmoins été traités (i.e. inductances partielles & couplages magnétiques parasites). Différentes méthodes ont été mises au point par le passé dans le but d'améliorer facilement la réponse du filtre. Cependant, il s'agit de procédés empiriques ne pouvant garantir l'optimalité de la solution de filtre construite. Les travaux réalisés au cours de cette thèse ont donc consisté à développer une nouvelle méthode d'optimisation d'un filtre CEM, et plus précisément de son routage. L'objectif est alors d'exploiter les différents phénomènes magnétiques parasites intrinsèques au montage. Calculer ce type d'éléments a donc nécessité l'utilisation d'un outil de modélisation PEEC ; méthode numérique permettant des calculs rapides en raison d'un maillage relativement limité. / The actual trend to integrate the power electronic devices naturally increases the stray electromagnetic phenomena. Every electrical system becomes thus an EM disturbances source. But as part of this work, we especially focused on the filtering device of conducted disturbances : the EMC filter. For high frequencies, degradations can be observed over the filter transfer function due to the different stray electromagnetic phenomena occurring within the device. But only the magnetic aspects have nevertheless been treated (i.e. partial inductances & stray magnetic couplings). Different methods have been worked out in the past in order to easily improve the filter response. However, these are empirical processes that could not guaranty the built filter solution optimality. The works done throughout this PhD have consisted in developing a novel EMC filter optimization method, and more precisely of its routing. The aim has been to use the different stray magnetic phenomena. All of these elements can only be obtained by using a PEEC modeling tool. The PEEC method allows having fast numerical calculations thanks to a quite light meshing.
12

MULTI-OBJECTIVE DESIGN OF DYNAMIC WIRELESS CHARGING SYSTEMS FOR HEAVY – DUTY VEHICLES

Akhil Prasad (9739226) 15 December 2020 (has links)
<p>Presently, internal combustion engines provide power to move the majority of vehicles on the roadway. While battery-powered electric vehicles provide an alternative, their widespread acceptance is hindered by range anxiety and longer charging/refueling times. Dynamic wireless power transfer (DWPT) has been proposed as a means to reduce both range anxiety and charging/refueling times. In DWPT, power is provided to a vehicle in motion using electromagnetic fields transmitted by a transmitter embedded within the roadway to a receiver at the underside of the vehicle. For commercial vehicles, DWPT often requires transferring hundreds of kW through a relatively large airgap (> 20 cm). This requires a high-power DC-AC converter at the transmitting end and a DC-AC converter within the vehicle. </p> In this research, a focus is on the development of models that can be used to support the design of DWPT systems. These include finite element-based models of the transmitter/receiver that are used to predict power transfer, coil loss, and core loss in DWPT systems. The transmitter/receiver models are coupled to behavioral models of power electronic converters to predict converter efficiency, mass, and volume based upon switching frequency, transmitter/receiver currents, and source voltage. To date, these models have been used to explore alternative designs for a DWPT intended to power Class 8-9 vehicles on IN interstates. Specifically, the models have been embedded within a genetic algorithm-based multi-objective optimization in which the objectives include minimizing system mass and minimizing loss. Several designs from the optimization are evaluated to consider practicality of the proposed designs.
13

Operation of Three Phase Four Wire Grid Connected VSI Under Non-Ideal Conditions

Ghoshal, Anirban January 2013 (has links) (PDF)
The necessity to incorporate renewable energy systems into existing electric power grid and need of efficient utilization of electrical energy are growing every day. A shunt connected Voltage Source Inverter(VSI) capable of bidirectional power flow and fast control has become one of the building block to address such requirements. However with growing number of grid connected VSI, new requirements related to harmonic injection, higher overall efficiency and better performances during short term grid disturbances have emerged as challenges. For this purpose a grid connected three phase four wire VSI with LCL filter can be considered as a general module to study different control approaches and system behavior under ideal and non-ideal grid conditions. This work focuses on achieving enhanced performance by analyzing effect of non-ideal conditions on system level and relating it to individual control blocks. In this work a phase locked loop structure has been proposed which is capable of extracting positive sequence fundamental phase information under non-ideal grid conditions. It can also be used in a single phase system without any structural modification. The current control for the three phase four wire VSI system has been implemented using Proportional Resonant (PR) controller in a per phase basis in stationary reference frame. A simplified controller design procedure based on asymptotic representation of the system transfer function is proposed. Using this method expressions for controller gains can be derived. A common mode model of the inverter system has been derived for low frequencies. Using this model a controller is designed to mitigate DC bus imbalance caused by sensor and ADC channel offsets. A multi-rate approach for digital implementation of PR controller with low resource consumption, that is suitable for an FPGA like digital controller ,is proposed. This multi-rate method can maintain resonance frequency accuracy even at low sampling frequency and can easily be frequency adaptive. Anti-wind up methods for PI controller have been studied to find suitable anti-wind up methods for PR controller. The tracking anti-wind up method is shown to be suitable for use with a PR controller. The effectiveness of this method under sudden disconnection and reconnection of VSI from grid is experimentally verified. A resonant integrator based second order filter is shown to be useful for active damping of LCL filter resonance with a wide range of grid inductance variation. The proposed method utilizes the LCL filter capacitor voltage to estimate resonance frequency current. Suitability of fundamental current PR controller for active damping alone, and with the proposed method show the superiority of the proposed method especially for low switching frequencies. Design oriented analysis of the above topics are included in the thesis. The theoretical understandings developed have been verified through experiments in the laboratory and can be readily implemented in industrial power electronic systems.

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