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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.
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Showing 81 to 83 of 83 (0.032 seconds)Spelling suggestions: "subject:"power grids"" "subject:"power vrids""
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A new family of dc-dc-ac power electronics convertersDarabi, Mostafa January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This thesis proposes a family of non-isolated bidirectional converter in order to
interface dc and ac variables. Such power electronics solutions guarantee: (i) bidirectional
power flow between dc and ac converter sides, (ii) independent control in both
converter sides, (iii) high level of integration with a reduction of one power switch
and its drive circuits, (iv) implementation of two functions by using a unique power
conversion stage and (v) reduction of the capacitor losses. Despite proposing new
power converter solutions, this thesis presents an analysis of the converters in terms
of pulse-width-modulation (PWM) strategy, dc-link capacitor variables, and suitable
a control approach.
Solutions for single-phase, three-phase and three-phase four-wire systems are proposed
by employing a converter leg with three switches. A possible application of
this converter is in Vehicle-to-Grid (V2G) systems and interfacing dc microgrid with
a utility grid.
In addition to the new power electronics converters proposed in this thesis, an
experimental setup has been developed for validation of the simulated outcomes. The
proof-of-concept experimental setup is constituted by: DSP, Drivers & Integrating
Board, Power Supply and, Power Converter & Heat-Sink .
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| 82 |
PV Based Converter with Integrated Battery Charger for DC Micro-Grid ApplicationsSalve, Rima January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This thesis presents a converter topology for photovoltaic panels. This topology minimizes the number of switching devices used, thereby reducing power losses that arise from high frequency switching operations. The control strategy is implemented using a simple micro-controller that implements the proportional plus integral control. All the control loops are closed feedback loops hence minimizing error instantaneously and adjusting efficiently to system variations. The energy management between three components, namely, the photovoltaic panel, a battery and a DC link for a microgrid, is shown distributed over three modes. These modes are dependent on the irradiance from the sunlight. All three modes are simulated. The maximum power point tracking of the system plays a crucial role in this configuration, as it is one of the main challenges tackled by the control system. Various methods of MPPT are discussed, and the Perturb and Observe method is employed and is described in detail. Experimental results are shown for the maximum power point tracking of this system with a scaled down version of the panel's actual capability.
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| 83 |
Energy conversion unit with optimized waveform generationSajadian, Sally January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / The substantial increase demand for electrical energy requires high efficient apparatus dealing with energy conversion. Several technologies have been suggested to implement power supplies with higher efficiency, such as multilevel and interleaved converters. This thesis proposes an energy conversion unit with an optimized number of output voltage levels per number of switches nL=nS. The proposed five-level four-switch per phase converter has nL=nS=5/4 which is by far the best relationship among the converters presented in technical literature. A comprehensive literature review on existing five-level converter topologies is done to compare the proposed topology with conventional multilevel converters. The most important characteristics of the proposed configuration are: (i) reduced number of semiconductor devices, while keeping a high number of levels at the output converter side, (ii) only one DC source without any need to balance capacitor voltages, (iii) high efficiency, (iv) there is no dead-time requirement for the converters operation, (v) leg isolation procedure with lower stress for the DC-link capacitor. Single-phase and three-phase version of the proposed converter is presented in this thesis. Details regarding the operation of the configuration and modulation strategy are presented, as well as the comparison between the proposed converter and the conventional ones. Simulated results are presented to validate the theoretical expectations. In addition a fault tolerant converter based on proposed topology for micro-grid systems is presented.
A hybrid pulse-width-modulation for the pre-fault operation and transition from the pre-fault to post-fault operation will be discussed. Selected steady-state and transient results are demonstrated to validate the theoretical modeling.
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