Important characteristic of any VLSI design circuit is its power reliability, high operating speed and low silicon area implementation. Dynamic CMOS designs provide high operating speeds compared to static CMOS designs combined with low silicon area requirement. The use of pipelines can also provide high circuit operating speeds. However, as the operating frequency increases, the number of pipeline stages should also increase and so the memory elements. These memory elements increases the area of implementation and restricts the maximum achievable frequency due to their delays. Memoryless pipelines based on dynamic design address these issues but, still requires high power consumption for the clock signal. In this thesis we present a sinusoidal three-phase clocking scheme that reduces the power required by the clock and offers high circuit operating frequencies. Thus the proposed technique provides advantages over preexisting techniques in terms of power requirement, area over head and operating speed.

In this thesis, the design of a voltage-source inverter (VSI)-based three-phase impedance analyzer's perturbation injection unit (PIU) is described including all relevant power stage and control design. Both series and shunt injection are examined from .1 Hz to 1000Hz. Both types of injection are performed using only energy from the system under test stored in a DC link capacitor. Sinusoidal, square (pulse), and chirp perturbation waveforms are explored. Results from a constructed realization of the design are presented, and the limits of the device characterized. The maximum achievable perturbation power is 10 kW in shunt and 8 kW in series on a 460 V, 100 kW bus. Using the same conditions, maximum power is achievable from 10Hz to 100Hz, at .1Hz, .72 kW is achievable, and at 1000Hz, 6.0 kW is achievable. / Master of Science

The goal of this thesis project was to design and build a three-phase inverter controlled by the TMS320F2812 DSP by Texas Instruments. The TMS320F2812 is controlled in order to make inverters generate output waveforms which mimic the main reference signal coming from a computer. The project included building three different inverters on two platforms including auxiliary circuits and designing five pulse width modulation (PWM) switching algorithms for the inverters. The motivation was that a newly designed inverter was required as an intermediary device between a computer and a laboratory-scaled model of a wind turbine. This type of wind turbine is used to educate students and engineers and to extract experimental wind power data. However, since commercial inverters don’t follow the main reference signal which is sent from the computer in order to operate the laboratory-scaled wind turbine, a controllable and variable inverter needed to be designed to receive that signal. The results are as follows. The voltage source inverter (VSI) and the current-controlled voltage source inverter (CC-VSI) were built on the VSI platform, and the current source inverter (CSI) was built on the CSI platform. Furthermore, the TMS320F2812’s analog digital converter (ADC) driver circuit and the output LC filter were also designed as auxiliary circuits. Five PWM switching programs were written; three switching algorithms for the VSI, and one algorithm each for the CC-VSI and the CSI. The output waveforms from the combination of hardware and software mentioned above were captured, and they follow the main reference signal very well. Although each of the inverters performed well, the VSI in combination with the Space Vector PWM switching algorithm produced the cleanest output voltage waveforms with the least amount of noise. The inverters built in this thesis project can be applied to the laboratory-scaled wind turbine, the maximum power tracking in solar panels, and equipment for analyzing digital signal processing. However, before using the inverters in those applications, much work remains to be done to solve the problems related to the signal distortion caused by the dead band time, harmonic signals caused by the fixed switching frequency, and the reliability issues caused by mounting on the bread board. In conclusion, although this thesis does not illustrate the entire process of or explain every requirement for building the three inverters, enough information about the topology of the inverters, the hardware design, and the PWM switching algorithms is provided in this thesis to enable one to remake all three of the three-phase inverters. / text

The objective of this study is to observe the correlations between variable operating conditions and power quality parameters for a three-phase to single-phase cycloconverter. The cycloconverter is examined in its most straightforward form without additional output filters or elaborate control methods. Variable operating conditions include input frequency, output frequency, and resistive load size. The power quality parameters of interest are power factor, input current total harmonic distortion (THD), output voltage THD, and efficiency. The scope of the project includes analytical calculations, PSpice simulations, as well as a hardware implementation. The results show that output frequency has minimal effect on power quality. High input frequencies tend to yield less efficiency and larger loads yield higher efficiency. Total harmonic distortion undesirably peaks at a combination of low input frequency and high output frequency. Extrapolations can be made for the cycloconverter operating at different frequencies and loads based on the trends observed within the test matrix.

Master of Science / Department of Electrical and Computer Engineering / Behrooz Mirafzal / Increasing energy demand, rising oil prices, and environmental concerns have forced attention to alternative energy sources that are environmentally friendly and independent of fossil fuels. Renewable energy sources (RES) have become an attractive alternative to the traditional energy sources for electric power generation. However, one of the main challenges of RES adaption arises when connecting RES to the electric grid. Voltage source inverters (VSIs), typically, connect RES to the electric grid. Similar to any engineering system, detailed dynamic models of the VSIs are needed for design and analysis purposes. However, due to the non-linearity of VSIs, development of dynamic models that can accurately describe their behavior is a complex task. In this thesis, a detailed averaged-state-space model of the two-level three-phase space vector pulse width modulation VSI and its companion LCL filter is derived. Because VSIs can operate under stand-alone and grid-tied modes, two models were derived for each case. In the derived models, the VSI modulation index m and phase angle ϕ are initially considered constant. In practice, however, these parameters are considered the main control parameters. To model these parameters as control inputs, small-signal models of the VSI under stand-alone and grid-tied modes were derived. To verify the accuracy of the developed large-signal and small-signal models, Matlab/Simulink simulations were carried out. The simulation results were compared against the models results. Moreover, the models were verified through lab experiments. The developed models can be used as design and analysis tools. In addition, the developed models can be used as fast and efficient simulation tools for system studies, when the modeling of switching transients is not needed. Nowadays, the number of VSIs connected to the electric grid is growing exponentially. The amount of time and computation needed to simulate VSIs using simulation software packages can be significantly decreased by the use of the developed models.

No description available.

A rigorous three-phase asphaltene precipitation model was implemented into a compositional reservoir simulator to represent and estimate the reduction of porosity and permeability responsible for productivity impairment. Previous modeling techniques were computationally inefficient, showed thermodynamic inconsistencies, or required special laboratory experiments to characterize the fluid. The approach developed in this study uses a cubic equation of state to solve for vapor/liquid/liquid equilibrium (VLLE), where asphaltene is the denser liquid phase. Precipitation from the liquid mixture occurs as its solubility is reduced either by changes in pressure (natural depletion), or composition (i.e. mixing resulting from gas injection). The dynamic relationship between phase composition, pressure, and porosity/permeability is modeled with a finite differences reservoir simulator and solved using an implicit-pressure, explicit-saturations and explicit-compositions (IMPESC) direct sequential method. The robustness of this model is validated by the ability to reproduce experimental asphaltene precipitation data while predicting the expected phase behavior envelope and response to key thermodynamic variables (i.e. type of components and composition, pressure and, temperature). The three-phase VLLE flash provides superior thermodynamic predictions compared to existing commercial techniques. Computer performance analysis showed that the model has a comparable cost to existing asphaltene precipitation models, taking only 1.1 more time to calculate but requiring fewer tunable parameters. The VLLE flash was in average 4.47 times slower compared to a conventional two-phase vapor/liquid flash. This model has the speed of a flash calculation while maintaining thermodynamic consistency, enabling efficient optimization of reservoir development strategies to mitigate the detrimental effects of asphaltene precipitation on productivity.

This thesis describes the development of a new generation of three-phase rectifier, used to power telecommunications equipment. The traditional topology for such power converters is a single-phase two-stage design, with a boost converter providing power factor correction at the input to the first stage and an isolated dc-dc converter making up the second stage. A two-stage design results in the output power being processed twice and this cascade effect results in an overall reduction in efficiency. A rectifier solution is sought that meets with all the requirements of the telecommunications industry, while not displaying the inherent weaknesses associated with a boost-derived topology, and which can be realised in a single-stage design. A number of common three-phase topologies exist that could be realised as telecommunication power supplies, however, they do not completely satisfy all the industry requirements. A new three-phase rectifier, which is a single-stage buck-derived topology, is proposed. As a consequence of incorporating a buck-derived topology, the three-phase rectifier does not exhibit any issues resulting from startup inrush currents, or high currents due to an output short circuit condition, as would result in a boost-derived topology. The new proposed rectifier is modular in nature, which has the added benefit of redundancy. As a result of the new three-phase rectifier having a single-stage topology, it is expected that the overall efficiency would able to reach close to 95%. This is due to the traditional two-stage designs having efficiencies around the 90% mark, and therefore by removing a stage, out of the power conversion process the overall losses would also be halved, resulting in the 5% gain in efficiency. The rectifier system requires only one controller as a result of being a single-stage design, thus also reducing the overall system cost. Simulations show that if this topology is combined with a three-phase phase-locked loop controller it can meet the industry compliance standards. The thesis follows the development of the three-phase power converter from the simulation stage to the realisation of the control hardware and stability modelling. It also provides a detailed report of an investigation into the power converter system’s performance. The thesis concludes with discussions concerning the viability of the new topology as a commercial product and indicates areas of possible future research and development.

This thesis deals primarily with the simulation and analysis of shunt active power filters (APF) on a three-phase power distribution system possessing a harmonic generating load. The shunt active power filters are analyzed based on effective total harmonic distortion (THD) levels and response to changing dynamics. These results are derived from the simulation of a pulse-width modulation (PWM) controlled voltage source inverter (VSI) with a capacitor connected to the DC side of the VSI. The primary difference between individual simulations is the particular control law implemented in the shunt APF.

A modified space vector modulation algorithm for a zero-voltage transition three-phase voltage source inverter/boost rectifier is presented. The converter is intended for high performance medium power applications requiring bi-directional power flow. The proposed modified space vector modulation allows the main switches to be operated with constant frequency and soft switching for any phase shift between the three-phase currents and voltages. The modulation algorithm also eliminates any low frequency distortion caused by the zero-voltage transition and can be extended to other soft-switching PWM three-phase converters. Experimental verification of the proposed algorithm is also presented as well as a comparison to the hard switched PWM converter. / Master of Science