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The Global ETD Search service is a free service for researchers
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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 90 of 90 (0.082 seconds)Spelling suggestions: "subject:"DC to DC converters"" "subject:"DC to DC konverters""
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High-power bi-directional DC/DC converters with controlled device stressesHan, Sangtaek 11 May 2012 (has links)
The objective of the research is to develop a cost-effective high-power bi-directional dc/dc converter with low total-device ratings, reduced system parasitic effects, and a wide input/output range. Additional objectives of the research are to develop a small-signal model and control methods, and to present performance characterizations. Device stresses in the proposed topology are controlled to maintain minimal levels by varying the duty ratio and phase-shift angle between the primary and the secondary bridges, which results in a low total-device rating, when compared to conventional bi-directional dc/dc topologies. In the proposed topology, soft switching, which reduces power loss, can be realized under specific operating conditions. When the condition that causes minimal device stress is satisfied, zero-voltage switching (ZVS) can be obtained. In the research, ZVS capability is explored for a wide range of voltage conditions as well as for the minimal device-stress condition. The performance characterization includes verifying the soft-switching regions and power-loss estimation. Another part of the thesis is the controller design of the converter. Small-signal models and feedback controllers are developed, and the controllers are experimentally validated. Because in the isolated high-frequency converters, transformer saturation is an important issue, a method to prevent transformer saturation is proposed and experimentally validated.
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| 82 |
Modeling and control of fuel cell based distributed generation systemsJung, Jin Woo, January 2005 (has links)
Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvi, 209 p.; also includes graphics. Includes bibliographical references (p. 202-209). Available online via OhioLINK's ETD Center
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| 83 |
Implementations of Fuzzy Adaptive Dynamic Programming Controls on DC to DC ConvertersChotikorn, Nattapong 05 1900 (has links)
DC to DC converters stabilize the voltage obtained from voltage sources such as solar power system, wind energy sources, wave energy sources, rectified voltage from alternators, and so forth. Hence, the need for improving its control algorithm is inevitable. Many algorithms are applied to DC to DC converters. This thesis designs fuzzy adaptive dynamic programming (Fuzzy ADP) algorithm. Also, this thesis implements both adaptive dynamic programming (ADP) and Fuzzy ADP on DC to DC converters to observe the performance of the output voltage trajectories.
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| 84 |
A Selective Polarity DC-DC Converter with Virtually Infinite Voltage LevelsLiu, Kaiyang 29 July 2016 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This research introduces a new design of a converter modified from SEPIC converter (Single end primary inductive converter), capable of generating desired voltage levels and polarities. The new switching converter topology allows for boost and buck of the input voltage theoretically achieving infinite positive and negative voltage levels. The proposed topology utilizes single high frequency switch to perform the power conversion which simplifies the design of the gate driver, but meanwhile, it still retains the ability to provide a wide range of output voltage. Mathematical modeling of the converter and computer simulations are validated by experimental data. To verify its performance a prototype was designed and built. It is experimentally proven that the circuit can generate a desired voltage in the range of voltages up to ±170 V, delivering 480 Watts of power to a resistive load.
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| 85 |
An impact study of DC protection techniques for shipboard power systemsHamilton, Hymiar, January 2007 (has links)
Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.
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| 86 |
Digitally assisted control techniques for high performance switching DC-DC convertersKhan, Qadeer Ahmad 25 June 2014 (has links)
Digitally controlled switching DC-DC converters have recently emerged as an attractive alternative to conventional switching converters based on analog control techniques. This research focuses on eliminating the issues associated with the state of the art switching converters by proposing three novel control techniques: (1) a digitally controlled Buck-Boost converter uses a fully synthesized constant ON/OFF time-based fractional-N controller to regulate the output over a 3.3V-to-5.5V input voltage range and provides seamless transition from buck to buck-boost modes (2) a hysteretic buck converter that employs a highly digital hybrid voltage/current mode control to regulate output voltage and switching frequency independently (3) a 10MHz continuous time PID controller using time based signal processing which alleviates the speed limitations associated with conventional analog and digital.
All the three techniques employ digitally assisted control techniques and require no external compensation thus making the controllers fully integrated and highly cost effective. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from June 25, 2012 - June 25, 2014
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| 87 |
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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| 88 |
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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| 89 |
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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| 90 |
A non-conventional multilevel flying-capacitor converter topologyGulpinar, Feyzullah January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This research proposes state-of-the-art multilevel converter topologies and their
modulation strategies, the implementation of a conventional flying-capacitor converter
topology up to four-level, and a new four-level flying-capacitor H-Bridge converter
confi guration. The three phase version of this proposed four-level flying-capacitor
H-Bridge converter is given as well in this study. The highlighted advantages of the
proposed converter are as following: (1) the same blocking voltage for all switches
employed in the con figuration, (2) no capacitor midpoint connection is needed, (3)
reduced number of passive elements as compared to the conventional solution, (4)
reduced total dc source value by comparison with the conventional topology.
The proposed four-level capacitor-clamped H-Bridge converter can be utilized as
a multilevel inverter application in an electri fied railway system, or in hybrid electric
vehicles.
In addition to the implementation of the proposed topology in this research, its
experimental setup has been designed to validate the simulation results of the given
converter topologies.
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