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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 33 for “"three-phase ac"”.
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A SiC JFET-Based Three-Phase AC PWM Buck Rectifier
… to be a major breakthrough for new generation ac three-phase power converters, offering increased junction temperature, low specific on-resistance, fast switching, and low switching loss. These characteristics are desirable for increasing power density, providing faster system dynamics, and …
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Online Measurement of Three-phase AC Power System Impedance in Synchronous Coordinates
… two decades there has been an increased use of three-phase AC power systems that may not be connected to the main power grid, such as the power systems on more-electric airplane and all-electric ships. Power-electronic converters are usually a significant part of these systems, which provide …
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Stability Analysis of Three-Phase AC Power Systems Based on Measured D-Q Frame Impedances
… and specification of these systems. In terms of three-phase ac systems, a mathematical framework based on the generalized Nyquist stability criterion (GNC), reference frame theory, and multivariable control is set forth for stability assessment. However, this approach relies on the actual …
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Analysis and Design for a High Power Density Three-Phase AC Converter Using SiC Devices
The development of high power density three-phase ac converter has been a hot topic in power electronics area due to the increasing needs in applications like electric vehicle, aircraft and aerospace, where light weight and/or low volume is usually a must. Many challenges exist due to the …
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Power electronic transformers for AC-AC and AC-DC conversion with reduced number of switches
… Power Electronic Transformer is proposed for three-phase power conversion (three-phase AC to AC as well as three-phase AC to DC). The goal of this project is to reduce the weight and size of the power converter by replacing the low-frequency transformers with high-frequency transformers …
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Observer based fault detection filters for three-phase inverters and statcoms
… which are sometimes crucial in determining the exact health of power electronic circuit components. This thesis develops and experimentally demonstrates a class of model-based fault detection and isolation filters for three-phase AC-DC power electronics systems that is able to detect all possible …
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Design and development of a traction motor emulator using a three-phase bidirectional buck-boost AC-DC converter
An industrial drive testing, with a ‘real-machine’ can pave way, for some serious issues to test-bench, motor, and the operator. A slight disturbance in control logic amid testing, can damage the physical machine or drive. Such dangerous testing conditions can be avoided by supplanting real motor …
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Modeling and control of a wind turbine as a distributed resource in an electric power system
… that consistent and efficient power is supplied according to the load requirements.;The objective of this thesis is to make a contribution to the ongoing wind turbine research in the areas of modeling, control and implementation of wind turbines as DRs in deregulated electric power systems. A …
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A frequency converter to power a soudronic VAA20 welding machine
This thesis covers the design, manufacture and testing of a frequency converter, that transforms three phase AC 380V, into one phase AC 50 to 120Hz, 100 to 650V. The inverter output is intended to power a Soudronic VAA2 O welding machine. The input to the converter was stepped down and rectified to …
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D-q impedance identification in three phase systems using multi-tone perturbation
… converters may bring instability problem to AC or DC distributed systems. Impedance based stability criteria has been proven a good tool for small-signal stability analysis. This works focuses on the developing of a comprehensive software tool which can extract DC or three phase AC …
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Implementation of a Digital Signal Processor (DSP) Based Space Vector Control of AC Induction Motor Drives
… how these pulse trains synthesize sine waves. AC waveform generation techniques such as the square wave and Pulse Width Modulation (PWM) are compared in terms of their harmonic elimination capability and fundamental gain control. Various PWM techniques such as bipolar switching, unipolar …
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Evaluation of two prototype three phase photovoltaic water pumping systems
Two prototype three phase AC photovoltaic pump systems (Solvo, ML T) and a DC PV pump (Miltek) were tested on a farm borehole in Namibia (latitude 21°6', longitude 17°6'). The PV array consisted of twelve modules (636Wpeak) mounted on a single-axis passive tracker. The depth of the water was 75m …
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Design and implementation of a microgrid-capable solar inverter
The notion of a practical microgrid -- a small, interconnected system of generators and loads that operates both synchronously with a larger, centralized grid and isolated from the grid, autonomously -- has grown popular as electric utilities are installed more frequently in areas lacking a …
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AC/DC power system small-signal impedance measurement for stability analysis
… the Nyquist stability criterion. Methods of extracting impedance in dc systems have been well established. However, for ac systems, the traditional current-injection techniques are not suitable, especially for the high power systems. The first contribution of this work is the unique process of …
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Output Impedance Modeling and Measurement of a 28 kW Synchronous Generator
Synchronous machines (SMs) are a vital part of today's world, and precise modeling is important for studying their stability. In this thesis, a small-signal analysis is done on the d-q frame for the AC SM. Starting from formulating the SM's abc frame equations, a d-q transformation is done based on …
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Applications of Power Electronic Converter Based Wideband System Identification in Grid Tied AC Power Systems
… However, if this information is fed back into the controller as a slower outer control loop, it can be used to recalibrate control parameters on the fly. This allows the control to maximize performance over a wide range of operating conditions. The purpose of this work is twofold: to …
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A new unity power factor quasi-resonant induction heater
… mode power converter techniques. The proposed three phase unity power factor induction heating system consists of two stages of power conversions. The important requirements for each stage of the power conversion of a typical induction heating system working from a three-phase supply are …
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A Three-Phase Single-Stage AC-DC ZVZCS PWM Full-Bridge Converter
It is standard practice to use two separate power converters to convert an ac input voltage to a desired and isolated dc output voltage. A front-end ac-dc converter is used to convert the input ac voltage into an intermediate dc voltage which is then fed into a dc-dc converter with transformer …
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A Three-Phase Single-Stage AC-DC ZVZCS PWM Full-Bridge Converter
It is standard practice to use two separate power converters to convert an ac input voltage to a desired and isolated dc output voltage. A front-end ac-dc converter is used to convert the input ac voltage into an intermediate dc voltage which is then fed into a dc-dc converter with transformer …
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Soft-switching techniques for high-power PWM converters
… high power PWM converters. These new topologies achieve soft-switching functions with minimum increase of device voltage/current stresses and converter circulating energy, and thus have advantages over conventional techniques in efficiency, power density, reliability, and cost of power …
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