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1
Davenport, Tattiana Karina Coleman. "Three-Phase Generation Using Reactive Networks." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1345.
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Household appliances utilize single-phase motors to perform everyday jobs whether it is to run a fan in an air conditioner or the compressor in a refrigerator. With the movement of the world going “green” and trying to make everything more efficient, it is a logical step to start with the items that we use every day. This can be done by replacing single-phase motors with three-phase motors in household appliances. Three-phase motors are 14% more efficient than single-phase motors when running at full load and typically cost less over a large range of sizes [1]. One major downside of incorporating three-phase motors in household appliance is that three-phase power is not readily available in homes. With the motor replacement, a single to three-phase converter is necessary to convert the single-phase wall power into the required three-phase input of the motor. One option is active conversion, which uses switches and introduces different stages that produce power loss [2]. An alternative solution is passive conversion that utilizes the resistances within the motor windings along with additional capacitors and inductors, which in theory are lossless. This study focuses on three different single to three-phase passive converters to run both wye and delta-connected three-phase induction motors, and a possible third winding configuration that utilizes one of the three converters. There will be an emphasis on proving the equivalency of two converters, one proposed by Stuart Marinus and Michel Malengret [11] and the other by Otto Smith [12]. Sensitivity analysis is performed to study the effects of variation of torque and converter component tolerances on the system.
2
Marinus, Stuart. "Using passive elements and control to implement single- to three-phase conversion." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/22647.
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Al-Zubaidi, Saif Thamer Fadhil. "A novel power conversion approach for single phase systems." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3971.
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A novel single phase rectification technique with a new architecture and control scheme is proposed. The new rectifier consists of switched capacitor branch in parallel with the diode bridge rectifier. The switched capacitor branch includes a capacitor and a bidirectional switch arranged in series so the switch can control the charging and discharging of the capacitor. The control strategy is carefully designed to ensure the output voltage of the rectifier is above a chosen threshold level and to maintain high input power factor with reduced line current harmonics. Circuit configuration, design parameters, principles of operation and the mathematical analysis are presented. The new architecture provides a reduction in the size of the DC side capacitor. This reduction can be as low as less than 10% of the size of the typical smoothing capacitor in the conventional single phase rectifier. The proposed concept is verified by the experimental results over a range of case studies. A novel buck-boost DC-DC converter architecture is also proposed. This converter utilises the close inversely-coupled inductors topology in both its conversion stages (buck and boost). The new converter aims to reduce the switching noise that usually accompanies the buck and boost circuits. This can be done by maintaining a continuous flow of current in both converter stages which results in a large reduction in the back e.m.f induced in the main inductor and thus reduces the switching noise. The new converter architecture also provides a unique design of the passive clamped circuit. This circuit is used to recycle the leakage energies of the coupled inductors which results in an efficiency improvement of the converter and to limit the voltage stress on the power switches. Circuit con figuration, principles of operation and the transfer function are presented. The proposed concept is verified by the experimental and the simulated results of a range of case studies. The highest achieved efficiency observed in the experiments was 97:7%.
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Wang, Kunrong. "High-Frequency Quasi-Single-Stage (QSS) Isolated AC-DC and DC-AC Power Conversion." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/29394.
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The generic concept of quasi-single-stage (QSS) power conversion topology for ac-dc rectification and dc-ac inversion is proposed. The topology is reached by direct cascading and synchronized switching of two variety of buck or two variety of boost switching networks. The family of QSS power converters feature single-stage power processing without a dc-link low-pass filter, a unidirectional pulsating dc-link voltage, soft-switching capability with minimal extra commutation circuitry, simple PWM control, and high efficiency and reliability.
A new soft-switched single-phase QSS bi-directional inverter/rectifier (charger) topology is derived based on the QSS power conversion concept. A simple active voltage clamp branch is used to clamp the otherwise high transient voltage on the current-fed ac side, and at the same time, to achieve zero-voltage-switching (ZVS) for the switches in the output side bridge. Seamless four-quadrant operation in the inverter mode, and rectifier operation with unity power factor in the charger (rectifier) mode are realized with the proposed uni-polar center-aligned PWM scheme. Single-stage power conversion, standard half-bridge connection of devices, soft-switching for all the power devices, low conduction loss, simple center-aligned PWM control, and high reliability and efficiency are among its salient features. Experimental results on a 3 kVA bi-directional inverter/rectifier prototype validate the reliable operation of the circuit. Other single-phase and three-phase QSS bi-directional inverters/rectifiers can be easily derived as topological extensions of the basic QSS bi-directional inverter/rectifier.
A new QSS isolated three-phase zero-voltage/zero-current-switching (ZVZCS) buck PWM rectifier for high-power off-line applications is also proposed. It consists of a three-phase buck bridge switching under zero current and a phase-shift-controlled full-bridge with ZVZCS, while no intermediate dc-link is involved. Input power and displacement factor control, input current shaping, tight output voltage regulation, high-frequency transformer isolation, and soft-switching for all the power devices are realized in a unified single stage. Because of ZVZCS and single-stage power conversion, it can operate at high switching frequency while maintaining reliable operation and achieving higher efficiency than standard two-stage approaches. A family of isolated ZVZCS buck rectifiers are obtained by incorporating various ZVZCS schemes for full-bridge dc-dc converters into the basic QSS isolated buck rectifier topology. Experimental and simulation results substantiate the reliable operation and high efficiency of selected topologies.
The concept of charge control (or instantaneous average current control) of three-phase buck PWM rectifiers is introduced. It controls precisely the average input phase currents to track the input phase voltages by sensing and integrating only the dc rail current, realizes six-step PWM, and features simple implementation, fast dynamic response, excellent noise immunity, and is easy to realize with analog circuitry or to integrate. One particular merit of the scheme is its capability to correct any duty-cycle distortion incurred on only one of the two active duty-cycles which often happens in the soft-switched buck rectifiers, another merit is the smooth transition of the input currents between the 60o sectors. Simulation and preliminary experimental results show that smooth operations and high quality sinusoidal input currents in the full line cycle are achieved with the control scheme.Ph. D.
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Mazza, Luan Carlos dos Santos. "Single phase bidirectional DAB DC-DC converter based on three state switching cell." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14412.
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This work presented is DC-DC isolated ZVS Bidirectional Dual Active Bridge (DAB) single phase converter, based three-state switching cell is presented. The proposal is to apply it in photovoltaic systems with battery bank into smart networks. Basically the drive control is the duty cycle (D) of the switches and the Phase Shift (φ) of the fundamental tensions between the bridges. The gyrator modeling of the converter is presented, highlighting its natural operating characteristic as gyrator. Shows the qualitative and quantitative analysis of the converter, realizing the full study of the stages of operation of the topology and checking all sixteen regions of operation. To obtain the regions of soft-switching, the fundamental model is applied. The design procedure of the converter is presented, and the results of simulations. A 2kW prototype was developed, aimed at obtaining experimental results validate the theoretical analysisNeste trabalho à apresentado o conversor CC-CC ZVS isolado bidirecional Dual Active Bridge (DAB) monofÃsico, baseado na cÃlula de comutaÃÃo de trÃs estados. A proposta à aplicÃ-lo em sistemas fotovoltaicos com banco de baterias em redes inteligentes. Basicamente o controle do conversor consiste na razÃo cÃclica (D) dos interruptores e o Phase Shift (φ) entre as componentes fundamentais das tensÃes entre as pontes. A modelagem por gyrator do conversor à apresentada, destacando-se sua caracterÃstica natural de funcionamento como gyrator. Mostra-se a anÃlise qualitativa e quantitativa do conversor, realizando o estudo completo das etapas de operaÃÃo da topologia e verificando todas as dezesseis regiÃes de operaÃÃo. Para obtenÃÃo das regiÃes de comutaÃÃo suave, à aplicado o modelo fundamental. O procedimento de projeto do conversor à apresentado, alÃm dos resultados de simulaÃÃes. Um protÃtipo de 2 kW foi desenvolvido, visando a obtenÃÃo dos resultados experimentais e validando a anÃlise teÃrica.
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Strahan, Richard Johnston. "Energy conversion by permanent magnet machines and novel development of the single phase synchronous permanent magnet motor." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1998. http://hdl.handle.net/10092/5602.
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Energy methods are widely used and well understood for determining the torque or force in machines which do not contain permanent magnets. Energy methods are employed to calculate torques or forces of magnetic origin after determination of the energy stored in the electromechanical coupling field. In this thesis, the energy stored in a permanent magnet system is defined, and the energy-coenergy relationship is determined. It is shown how residual magnetism can be incorporated into classical electromechanical coupling theory. It is therefore shown how equations for torques or forces can be derived for permanent magnet systems using energy methods.
An analytical method of calculating permanent magnet reluctance torque is developed. The method uses an elementary expression for the magnetic field to obtain the stored energy. This enables an analytical expression for the reluctance torque waveform to be obtained. The method is demonstrated to provide a powerful and fast design tool. The method can be generally applied to reluctance torque problems where the airgap is reasonably smooth.
The single phase synchronous permanent magnet motor is used in domestic appliances. It is a motor of very simple construction and high reliability, which is directly connected to an AC mains supply, and runs at synchronous speed. It is becoming increasingly used in preference to the shaded pole induction motor. However, its application is limited by the following characteristics. There is no control over the final direction of rotation, unless a mechanical blocking device is used. There are rotor positions at which only a very small starting torque is available. The characteristic twice electrical frequency torque pulsation yields a speed modulation of the same frequency, which can cause acoustic noise problems. A method of improving torque quality by improving the motor design is proposed to alleviate these limiting characteristics. This is achieved by designing a permanent magnet reluctance torque which cancels out the effect of the backward rotating component of the stator field. In this novel design, the permanent magnet reluctance torque effectively acts as a second balancing phase.
An unconventional technique for starting a single phase synchronous permanent magnet motor is demonstrated. This technique uses an inductive reluctance torque, provided by placing a suitably shaped iron lamination on the rotor, to rotate the rotor to a position from which starting can occur.
7
Unal, Teoman. "Design Of A Single-phase Full-bridge Diode Rectifier Power Factor Corrector Educational Test System." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12608148/index.pdf.
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In this thesis an educational test bench for studying the power quality attributes of the
commonly used single-phase full-bridge diode rectifiers with power factor correction
(PFC) circuits is designed and tested. This thesis covers the active and passive power
factor correction methods for single-phase bridge rectifier. Passive filtering approach
with dc side inductor and tuned filter along with active filtering approach via singleswitch
boost converter is considered. Analysis, simulation, and design of a single phase
rectifier and PFC circuits is followed by hardware implementation and tests. In the active
PFC approach, various control methods is applied and compared. The educational bench
is aimed to useful for undergraduate and graduate power electronics course, power
quality related laboratory studies.
8
Ozkan, Ziya. "Leakage Current And Energy Efficiency Analyses Of Single Phase Grid Connected Multi-kva Transformerless Photovoltaic Inverters." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614236/index.pdf.
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In order to inject solar power to the utility grid, among various types of inverters, Grid Connected Transformerless Solar Inverters (GCTSI) are mostly preferred for residential or commercial applications. This preference is because of the high energy efficiency and low cost due to the absence of a line frequency or a high frequency transformer. Peak value of the efficiency characteristics of GCTSIs can reach 98%, which are selected topology, component optimization, switching strategy and operating condition dependent. In spite of the attractive energy efficiency characteristics of GCTSIs, due to the lack of galvanic isolation, these inverters are vulnerable to leakage currents, which are prohibitive for the safety and the maintenance reasons. The purpose of this research is to analyze GCTSIs in terms of their leakage current and energy efficiency characteristics. In the research, the leakage current mechanisms of GCTSIs are identified and grid connected solar inverters are classified in terms of their leakage current characteristics including the GCTSIs. In addition to the existing ones, several novel topologies are proposed enriching the family of GCTSIs. The leakage current and the inductor current ripple performances of GCTSI topologies are analyzed and evaluated by detailed simulations for 3 kVA and 10 kVA single-phase systems. In addition, the energy efficiency characteristics of GCTSIs are investigated in these power levels by making use of Calculated Average Power Per Switching Cycle (CAPPSC) method. The efficiency studies with CAPPSC method provide design guidelines and comparison of the GCTSI topologies in terms of their energy efficiency characteristics.
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Forrest, Eric Christopher. "Study of turbulent single-phase heat transfer and onset of nucleate boiling in high aspect ratio mini-channels to support the MITR LEU conversion/." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92100.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 409-425).
Heat transfer in high aspect ratio mini-channels has important applications for materials test reactors using plate-type fuel. These fuel plates typically possess coolant channels with hydraulic diameters on the order of 4 mm or less. The single and two-phase heat transfer in such channels has not been well-characterized, especially in regard to the onset of nucleate boiling. While surface effects are known to dramatically influence the incipience of boiling, they have not been widely considered under forced convection. Since the limiting safety system setting for the MITR is the onset of nucleate boiling, there is considerable interest in better characterizing the phenomenon in such channels. This study presents a first-of-a-kind, two-phase flow facility designed to measure the single-phase heat transfer coefficient and onset of nucleate boiling in a high aspect ratio mini-channel over a wide range of flow conditions while also permitting high speed visualization of the entire surface. The single-phase heat transfer coefficient is measured for mass fluxes ranging from 750 kg/m2-sec up to 6000 kg/m2 -sec and for sub-coolings ranging from 20 °C to 70 °C. The onset of nucleate boiling superheat and heat flux are measured for mass fluxes ranging from 750 kg/m2- sec to 3000 kg/m2-sec and for sub-coolings ranging from 10 °C to 45 °C. Measurements are supported with high speed videography to visualize bubble incipience when conditions permit. The influence of surface wettability on the incipience point is also investigated by performing tests on a surface oxidized at high temperature in air. Using a boundary layer analysis along with experimental data obtained in the study, a semi-analytical correlation is developed to predict the single-phase heat transfer coefficient in high aspect ratio rectangular channels. The correlation accounts for effects from secondary flows and heating asymmetry, and is suitable for both the transition and fully turbulent flow regimes. The new correlation predicts the Nusselt number with a mean absolute error of 4.9% in the range of 2.2
Ph. D.
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Gurunlu, Cemil. "Single-phase operations of three-phase generators." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/32922.
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The ever-increasing demand for power, and the correspondingly greater complexity of power systems, is leading to more severe problems of system reliability. Modern society is so dependent on the usage of electrical power that even a short interruption of service can cause serious problems. A public utility cannot be expected to provide a perfect power supply, since many of the possible causes of a power disturbance are beyond its control. The windings of small diesel-driven three-phase generator sets are often capable of being connected in either a zig-zag or an Edison-delta arrangement, to provide a single-phase supply for standby or emergency purposes. Although many of these generators are genuinely on standby (i.e. they are brought into operation only as a result of a system failure), many others operate continuously in situations where no mains supply is available. The thesis aims to investigate both the steady-state and the dynamic performance of a three-phase salient-pole generator, when reconnected in either a zig-zag or an Edison-delta configuration, and to provide a performance comparison with the more familiar modes of single-phase operation involving line-to-line and line-to-neutral loading. Symmetrical components are used to investigate the steady-state performance and a phase model is used to determine both the steady state and transient performance. Analytical expressions are obtained for the short-circuit currents for various generator connections by utilizing the modified Clarke transformation. The theoretical results from various models are compared with experimental results on a test machine. Losses, efficiency and voltage waveforms for various generator connections are experimentally obtained for the test machine. Results are discussed and suggestions for future research are included.
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Chen, Weilun Warren. "Bidirectional Three-Phase AC-DC Power Conversion Using DC-DC Converters and a Three-Phase Unfolder." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6905.
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Strategic use of energy storage systems alleviates imbalance between energy generation and consumption. Battery storage of various chemistries is favorable for its relatively high energy density and high charge and discharge rates. Battery voltage is in dc, while the distribution of electricity is still predominantly in ac. To effectively harness the battery energy, a dc-ac inverter is required.
A conventional inverter contains two high-frequency switching stages. The battery-interfacing stage provides galvanic isolation and switches at high frequency to minimize the isolation transformer size. The grid-interfacing stage also operates at high frequency to obtain sinusoidal grid currents and the desired power. Negative consequences of high-frequency switching include increased switching loss and the generation of large voltage harmonics that require filtering.
This dissertation proposes an alternative two-stage inverter topology aimed at reducing converter size and weight. This is achieved by reducing the number of high-frequency switching stages and associated filter requirements. The grid-interfacing stage is operated at the line frequency, while only the battery-interfacing stage operates at high frequency to shape the line currents and control power flow. The line-frequency operation generates negligible switching loss and minimal current harmonics in the grid-interfacing stage. As a result, the required filter is reduced in size. Hardware designs are performed and compared between the conventional and proposed converters to quantify expected size reduction. Control methods are developed and verified in simulation and experiment to obtain high-quality line currents at all power factors.
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Vlatkovic, Vlatko. "Three-phase power conversion using soft-switching PWM techniques." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40059.
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This dissertation addresses several key issues related to high-frequency soft-switching PWM three-phase power converters. These are:
1. Analysis, synthesis, and design of three-phase soft-switching PWM power converter topologies
2. Design of input EMI filters for three-phase converters
3. Design of microprocessor controllers for three-phase converters.
An analysis of existing soft-switching PWM techniques is performed, and two generalized soft-switching PWM converter circuit representations are derived.
Based on these representations and common topological properties of three-phase and dc-dc PWM converters, two new procedures for synthesis of three-phase soft-switching PWM converters are derived. The two procedures are used to synthesize five new three-phase soft-switching PWM converter topologies suitable for wide range of applications.
A digital signal processor-based controller implementation example is presented. It demonstrates the feasibility of producing versatile, high performance, reliable, low-cost digital controllers for soft-switching PWM three-phase power converters operating at high switching frequencies.
A new approach to the design of input filters for ac power electronic circuits
is presented here. This approach is based on the application of a vast
body of knowledge about passive L-C filters that has existed for many years,
but has not been used in power electronics. New passive and active filter pole
damping schemes are applied to high-order elliptic filters, resulting in significant
filter size reduction compared to the standard filter designs.Ph. D.
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Xue, Jing. "Single-phase vs. Three-phase High Power High Frequency Transformers." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/32919.
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This thesis proposes one comparison methodology for single and three-phase high power high frequency transformers in power conversion systems. The objective is to compare the volume of the transformers. And single and three-phase Dual Active Bridge Converter (DAB1 and DAB3) topologies with single and three-phase isolating transformers are selected for the transformer comparison. Design optimization of power transformer has been studied and simplified models have been built for the single and three-phase transformer design optimization in this work, including assumptions for core shapes, materials, winding structures and thermal model. Two design methods have been proposed according to different design constraints, named T â B Method and J â B Method separately. T â B Method is based on feature of the core, which has the major limits of maximum flux density and temperature rise. The flux density should not reach the saturation value of the core, and temperature rise should meet specifications in different applications to assure the performance of the core (permeability, saturation flux density, and core loss) and the insulation of the wire. And J â B Method starts from the comparison of area product in conventional design method. The relationship between area product of transformer cores and the flux and current of the transformer in design is analyzed. There is specified relationship between area product of single and three-phase transformers if flux and current densities are specified for both. Thus J â B Method is proposed with the design constraints of specified current and flux density. Both design methods include both single and three-phase transformer design.
One example case for single and three-phase transformer comparison is selected as high power high frequency DAB conversion system. Operation principles are studied for both DAB1 and DAB3 based on previous work. And transformer design based on the T â B and J â B Methods are carried out and transformer volumes are compared. And results show that three-phase transformer has little benefit in volume or thermal than single-phase transformer, when they are utilized in single-phase DAB and three-phase DAB converters separately. Scaled-down single and three-phase DAB systems have been built and volume and thermal tests have been carried out.Master of Science
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Beber, DG. "DSP controlled three phase to single phase uninterruptible power supply." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5244.
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Includes bibliographical references.With the increase in use of electronic equipment such as personal computers, network stations and AC drive conrollers, an increased "polution" of the AC mains has resulted in the form of unwanted harmonics generated by the switching currents associated with these devices. Combined with the problem of mains "pollution" is the problem of balancing a large number of single phase loads onto a three phase supply, such as in a large computer network. This has resulted in more frequent supply voltage failure, causing substantial data and financial loss and in the extreme case death due to hospital equipment not being powered. Thus the need for an uninterruptible power supply (UPS) which is capable of resolving these problems. Taking these considerations into account, a three to single phase converter topology was developed and tested, using a Texas Instruments TMS320F243 Digital Signal Processor (DSP) for control of the system. The topology is based on a technique that utilises minimal semiconductor devices whilst still allowing for sinusoidal current to be drawn from the mains supply.
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Magozore, Caxton. "DSP phase angle controlled three phase to single phase uninterruptible power supply." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/5177.
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Zoric, I. "Multiple three-phase induction generators for wind energy conversion systems." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/8387/.
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During the past decade, there has been a considerable increase in the number of published works on multiphase machines and drives. This increased interest has been largely driven by a need for the so-called green energy, i.e. energy generated from renewable sources such as wind, and also an increased emphasis on greener means for transportation. Some of the advantages multiphase machines offer over three-phase counterparts are better fault tolerance, smaller current and power per phase, and higher frequency torque ripple. This thesis examines use of a multiphase induction generator in wind energy conversion systems (WECS). In particular, multiphase generators that comprise multiple 3-phase winding sets, where each winding set is supplied using an independent 3-phase voltage source inverter (VSI), are studied. It is claimed that these topologies offer advantages in cases where a WECS is connected to a multitude of independent ac or dc microgrids, systems where a single high-voltage dc link is needed or where a simple fault tolerance is achieved when a complete winding set is switched off. All of these examples require an arbitrary power or current sharing between winding sets. In order to achieve arbitrary current and power sharing, the control can be implemented using multi stator (MS) variables, so that the flux and torque producing currents of each winding set can be arbitrarily set. As an alternative, this thesis uses vector space decomposition (VSD) to implement the control, while individual winding set flux/torque producing currents are governed by finding the relationships between MS and VSD variables. This approach has all the advantages of both MS and VSD, i.e. access to individual winding set variables of MS and the ability to implement control in the multiple decoupled two dimensional subspaces of VSD, while heavy cross coupling between winding set variables, a weakness of MS, is avoided. Since the goal of the thesis is to present use of multiphase machines in WECS, modelling and simulation of a simple multiphase WECS in back-to-back configuration has been performed at first. All systems relevant to machine control where considered, such as grid and machine side VSIs, grid filter, indirect rotor field oriented control, current control in both flux/torque producing and non-producing subspaces, low order harmonic elimination, maximum power point tracking control, and voltage oriented control of the grid side VSI. Moreover, various WECS supply topologies were considered where developed current and power sharing would be a necessary requirement. Development of the proposed current sharing control commences with an analysis of multiple 3-phase machine modelling in terms of both MS and VSD variables. Since the actual control is implemented using decoupled VSD variables, VSD modelling has been studied in detail, resulting in an algorithm for creation of the VSD matrix applicable to any symmetrical or asymmetrical multiphase machine with single or multiple neutral points. Developed algorithm always decouples the machine into orthogonal two-dimensional subspaces and zero sequence components while making sure that all odd-order harmonics are uniquely mapped. Harmonic mapping analysis is offered as well. Next, relationship between MS and VSD variables has been developed by mapping MS variables into VSD subspaces. Since VSD matrix creation algorithm is valid for any multiphase machine, relationship between MS and VSD variables is applicable to any multiple 3-phase machine regardless of the configuration (symmetrical/asymmetrical), number of neutral points or machine type (synchronous or induction). Established relationship between MS and VSD has been used to implement current sharing control in decoupled VSD subspaces of the machine. It is shown that in order to achieve arbitrary current sharing it is only necessary to impose currents in flux/torque non-producing subspaces. Hence, total machine’s flux and torque are not affected at all. Besides verification by Matlab simulations, two topologies are experimentally investigated, a parallel machine side converter configuration and the case when a single high voltage dc link is created by cascading dc-links of the machine side VSIs. In the first case the ability of arbitrary current sharing between winding sets is validated, while the second tested topology demonstrates use of the developed control for the purpose of voltage balancing of the cascaded dc links.
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Kumar, Rajiv. "Programmed harmonic reduction in single phase and three phase voltage-source inverters." Ohio : Ohio University, 1996. http://www.ohiolink.edu/etd/view.cgi?ohiou1178302407.
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Ashrafi-Monfared, ShI. "Adaptive single to three-phase converter using variable passive elements." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/5238.
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Includes bibliographical references.The main objective of this thesis is to investigate the possible methods of converting a single-phase supply to a three-phase balanced voltage, using passive elements. Three distinct methodologies have been developed, each with its own merits and constructed prototypes. The seven chapters of this thesis contain large amound of non-real and real-time simulated results. These results were then compared with the experimental results.
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Douglas, Hugh. "A single three phase variable speed drive with unity power factor." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5274.
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Bibliography: leaf 86.The new proposed topology for a single three-phase variable speed drive was developed after considering the advantages and disadvantages of previous topologies. The new topology employs only six switches that form and active front-end rectifier and a four-switch inverter. The active front-end rectifier is the first leg of the three-phase bridge. It not only rectifies the voltage source but it also regulates one of the phases for the motor. The four-switch inverter produces the variable frequency. Excessive distortion currents drawn by a converter can cause voltage distortions. For this reason the converter should draw a high quality sinusoidal current from the supply. Excessive currents drawn from the supply are also the result of poor power factors. The converter should therefore operate at close to unit power factor. N Mohan, T Underland, W.P Robins [3].
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TENÓRIO, JÚNIOR Gilberto Alves. "Inversores Fonte Z monofásicos e conversor de dois estágios para sistemas fotovoltaicos sem Transformador." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/19498.
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Este trabalho apresenta um estudo comparativo de conversores monofásicos aplicados a sistemas fotovoltaicos sem transformador. Topologias de inversores sem transformador têm menores custos, tamanho e peso. Contudo, a não utilização do transformador pode ser responsável por consideráveis valores de correntes de fuga. A associação em série de vários módulos fotovoltaicos se faz necessária para alcançar o nível de tensão desejado no barramento c.c.. Com o intuito de reduzir o número de módulos fotovoltaicos em série, topologias com característica de elevação de tensão (boost) podem ser utilizadas. Portanto, topologias que possuem estas características e que possam apresentar baixos valores de correntes de fuga devem ser escolhidas para o estudo. As topologias presentes neste trabalho são: o conversor de dois estágios, o inversor fonte Z monofásico com diodo adicional, e o inversor fonte Z de três estados.
This work presents a comparative study of single-phase converters applied to transformerless photovoltaic systems. Topologies of transformerless inverters have lower costs, size and weight. However, not using it may cause considerable amounts of leakage currents. The association in series of several PV modules is needed to achieve the voltage level desired in d.c. bus. In order to reduce the number of photovoltaic modules in series, topologies with voltage boost characteristic can be used. Therefore, topologies that have voltage boost characteristic and can have low leakage current values are chosen for the study. Topologies present in this work are: the two stages single-phase converter, the single-phase Z-source inverter with additional diode, and the single-phase three switch three state Z-source inverter.
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Montoya, Higinio Ariel. "Protection Against Ungrounded Single Phase Open Circuit Faults in 3-Phase Distribution Transformers." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1869.
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This thesis explores the impacts and behavior of 3-phase distribution transformers when subject to ungrounded single phase open circuit faults. A simple 3-phase system is modeled using MATLAB Simulink and operation under fault conditions are simulated and studied. Simulation results are confirmed via lab experimentation. Finally, a robust detection and protection method using neutral current injection (as proposed in industry literature) is built and demonstrated.
Electric utility operating experience has demonstrated that all too often, loads on 3-phase distribution transformers are not adequately protected against an ungrounded single phase open circuit fault (commonly called “single phasing”). This type of fault is amongst the least understood and hence the least protected against. This is especially true at end of transmission system radial feeds where 3-phase transformers can re-create the opened phase voltage due to a variety of effects including magnetic coupling, voltage loops and loading effects. Operating experience in the nuclear power industry has shown that the results can be catastrophic especially considering the impacts to motor loads. Impacts can result in unavailability of emergency loads, tripping of motor protection circuits or even motor damage and failure.
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Gatarić, Slobodan. "Single-switch three-phase zero-current-transition rectifier with power factor correction /." This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12162009-020342/.
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Gatari?, Slobodan. "Single-switch three-phase zero-current-transition rectifier with power factor correction." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/46258.
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A novel, zero-current-transition (ZCT) topology of the single-switch three-phase boost PFC rectifier is proposed. The soft transition is achieved with a low-power auxiliary circuit employing an additional switch. The circuit can be used with an IGBT at switching frequencies up to 50. Its operation is analyzed in detail, and design guidelines are provided. The small signal model of the circuit is developed, and voltage mode control is designed. The results are verified on a 4 kW, 50 kHz, experimental ZCT rectifier with an IGBT; total harmonic distortion below 9% and efficiency above 95% were obtained.
Master of Science
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Jose, Della. "Comparison of a three phase single stage PV system in PSCAD and PowerFactory." Thesis, KTH, Elektriska energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103188.
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The main objective of the project is to develop a Photovoltaic (PV) system using three phase Pulse Width Modulation (PWM) converter as the interfacing component in Power factory. Already existing model in Power factory tool uses static generator as the interfacing converter. Moreover the control technique implemented within the PV model is very basic. Aworking model is already available in PSCAD simulation tool using PWM converter but it is a very detailed one in terms of modeling which results in longer simulation time. Through this project a new PV model is developed in Power factory, an improved version of existing PSCAD and Power factory models. Then a comparison study is carried out between the PSCAD and the new Power factory model in order to validate the created model’s functionality. Several case studies with the DC and AC side disturbances are performed to analyze the behavior of two models. The new PV model is found to function very similar to that of the existing PSCAD model, thus proving its credibility. Further improvements and additional functions are also included in the new Power factory model which makes it a better choice to carry out grid studies than the existing model in PSCAD.
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Chunkag, Viboon. "Three-phase power-factor correction using single-switch and parallel connected switching converters." Thesis, University of Bath, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336239.
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AraÃjo, Renato Guerreiro. "PLL (Phase-Locked Loop) structures for single phase and three phase systems with a high rejection capacity to sub and interharmonic." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=15882.
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CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorIn applications related to power converters, such as inverters, rectifiers and the use of active filters, the synchronization method represent a very important element in the performance of the control strategy of this equipment. The estimated values of the synchronism angle, frequency and amplitude determined by the synchronization algorithms present, facing strongly distorted signals with the presence of sub and interharmonics, high errors. This study presents two algorithms: one applied on single-phase electrical systems and one applied on three-phase electrical systems, with high immunity to interharmonics and subharmonics. First are presented the main synchronization systems that are used in the electrical power systems. In addition, will be presented the main causes and consequences of the presence of subharmonics and interharmnics in the system, as well as the mathematical modeling of the two algorithms with high rejection to these disturbances. Will be presented the simulation and the experimental results of the proposed algorithms and the comparison between these synchronization methods with particular methods present in the literature. As a result of the study, it can be seen that the proposed structures present a higher response time, but the error of the estimated signal with respect the fundamental component of the input signal is lower when compared to structures such as EPLL and structures based on SOGI. It was observed that the proposed synchronization methods are enabled to estimate the synchronism angle, the frequency and the fundamental component of the input signal adequately and can be used in control strategies of power converters.
Em aplicaÃÃes relacionadas à EletrÃnica de PotÃncia, como inversores, retificadores e a utilizaÃÃo de filtros ativos, o mÃtodo de sincronizaÃÃo representa um elemento chave no desempenho da estratÃgia de controle destes equipamentos. Os valores do Ãngulo de sincronismo, frequÃncia e amplitude estimados com determinados algoritmos de sincronizaÃÃo apresentam, diante de sinais fortemente distorcidos com a presenÃa de sub e inter-harmÃnicos, erros elevados. Neste trabalho sÃo apresentados dois algoritmos: um aplicado a sistemas elÃtricos monofÃsicos e outro aplicado a sistemas elÃtricos trifÃsicos, com elevada imunidade a inter-harmÃnicos e sub-harmÃnicos. Primeiramente sÃo apresentados os principais sistemas de sincronizaÃÃo utilizados em sistemas elÃtricos de potÃncia. AlÃm disso, sÃo apresentadas as principais causas e consequÃncias da presenÃa de sub-harmÃnicos e inter-harmÃnicos no sistema, bem como a modelagem matemÃtica dos dois algoritmos com elevada rejeiÃÃo a estes distÃrbios. SÃo apresentados os resultados de simulaÃÃo e experimentais dos algoritmos propostos e a comparaÃÃo entre estes mÃtodos de sincronizaÃÃo com determinados mÃtodos presentes na literatura. Como resultado do estudo, pode-se observar que as estruturas de sincronizaÃÃo propostas apresentam um tempo de resposta mais elevado, porÃm o erro do sinal estimado em relaÃÃo a componente fundamental do sinal de entrada à inferior quando comparado a estruturas como o EPLL e estruturas baseadas no SOGI. Com isso, tem-se que as mesmas estÃo habilitadas para estimar o Ãngulo de sincronismo, a frequÃncia e a componente fundamental do sinal de entrada adequadamente e podem serem utilizadas eficientemente em estratÃgias de controle de conversores de potÃncia.
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Carlton, Dan. "Low harmonic content three-phase-to-DC-conversion using AC-side switches and discontinuous conduction mode." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0032/NQ38862.pdf.
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Yao-hui, Wang, and 王耀輝. "Three-Phase/Single-Phase Power Conversion System." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/15613927553968646833.
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碩士崑山科技大學
電機工程研究所
95
In this thesis, a three-phase/single-phase power conversion system is developed. The three-phase/single-phase power conversion system is configured by a power converter, a zero-sequence transformer set and a filter capacitor. The three-phase/single-phase power conversion system can be applied to the three-phase distribution power system to perform a single-phase power conditioner. In this application, the three-phase/ single-phase power conversion system absorbs a real power from the three-phase distribution power system, and it will perform the functions of three-phase balance, low harmonic distortion and unity power factor in spite of single-phase load used. Moreover, the three-phase/single-phase power conversion will supply a single-phase voltage with high power quality for supplying power to the single-phase load. The three-phase/ single-phase power conversion system can also be applied to the small capacity wind power generation system for converting the unregulated three-phase power to a high quality single-phase power and being injected to the single-phase distribution power system. In this application, the three-phase/single-phase power conversion system can perform the functions of three-phase current balance, low harmonic distortion and unity power factor for operating the three-phase power generator smoothly, and a new maximum power point tracking method is developed to extract the maximum power of small-capacity wind power system. Additionally, the three-phase/single-phase power conversion system can also generate a current which is sinusoidal and in phase with the voltage to the single-phase distribution power system. Since the proposed three-phase/single-phase power conversion system contains only one power converter, it has the advantages of simplifying the power circuit and control circuit.
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Lu, Wei-Tso, and 盧唯佐. "Single-Phase/Three-Phase Power Conversion System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/w6edtd.
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碩士崑山科技大學
電機工程研究所
96
In this thesis, a single-phase/three-phase power conversion system is developed. The single-phase/three-phase power conversion system is configured by a three-phase four-wire power converter, a zero-sequence transformer set and a filter capacitor. The single-phase/three-phase power conversion system is applied to the single-phase distribution power system to perform a three-phase power conditioner. The current-mode control is applied to control the three-phase four-wire power converter so as to generate a positive-sequence current and a zero-sequence current. The positive-sequence current is used to generate the high-quality three-phase voltage suppling to the load. The zero-sequency current is passed to the single-phase distribution power system through the zero-sequency transformer such that the input current of single-phase/three-phase power conversion system is sinusoidal and in phase with the voltage of single-phase distribution power system. Since the proposed single-phase/three-phase power conversion system is configured by only one power converter, it has the advantages of simplifying the power circuit and control circuit. For verifing the performance of the proposed single-phase/three-phase power conversion system, a DSP-based hardware prototype is established and test.
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Chiang, L. Y., and 江律穎. "Study and Implementation of the Single-phase Three-wire Photovoltaic Energy Conversion System." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/88367529354079093842.
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Chang, Yi-Hua, and 張益華. "Analysis and Design of a Single-Phase Three-Wire Photovoltaic Energy Conversion System." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/07610266955170681624.
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碩士南台科技大學
電機工程系
92
This thesis presents a single-phase three-wire photovoltaic(PV) energy conversion system. When the proposed system is operating at the maximum power point, the energy is fed to the utility with sinusoidal wave. In low insolation environment, the proposed system operates at the function of active power filter and battery charger. When the utility is fault, the system is disconnected from the utility source. Instead of using a full-bridge inverter with a centric-tapped transformer, this thesis proposed a three-leg converter to yield single-phase three-wire circuit, thus resulting in a smaller physical volume and lower weight. Moreover, this system can feed energy to residential load continuously, even when the utility is interrupted. So this system include the function of the off-line uninterruptible power supply(UPS) type performance. The proposed control system is decoupled into differential-mode and common-mode subsystems. Finally, a 1kVA experimental prototype was built to demonstrate the performance of the proposed techniques.
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Wang, Wen-Jer, and 王文哲. "Study and Implementation of the Single-stage Three-phase Photovoltaic Energy Conversion System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/75433269780847688476.
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碩士國立成功大學
電機工程學系碩博士班
91
The study and implementation of a DSP-based digital controller for the single-stage three-phase photovoltaic（PV） energy conversion system is proposed in this thesis. The proposed maximum power point tracking strategy allows PV energy conversion system to track the maximum power point rapidly and smoothly. The proposed PV energy conversion system acts as a solar generator on sunny days and as an active power filter under low insolation conditions. In addition, the proposed controller performs maximum power point tracking and also provides power to utility with unity power factor. Moreover, the current controller with single loop is simple and easy to design, as compared with the conventional double loop controller. Finally, experimental results demonstrate the desired performance of the proposed technique.
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Chen, lone tai, and 陳榮泰. "Study and Implementation of the DSP-based Single-phase Three-wire Photovoltaic Energy Conversion System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/17333822651961593934.
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碩士國立成功大學
電機工程學系
89
Abstract The design and implementation of DSP-based digital controller for a grid-connected multi-function photovoltaic(PV) energy conversion system of single-phase three-wire is presented in this thesis. When the PV energy conversion system was operated at maximum power point, the solar power supports to the load and the surplus power is fed to the utility . As the low insolation, the system was operated as an active power filter(APF). Besides, the protecting functions of a grid-connection photovoltaic inverter system are include in system to prevent the islanding effect. In this thesis, a PV energy conversion system is constructed by single power stage without extra storage devices─batteries, and a three-leg inverter is used to yield output voltage without output transformer. Therefore, the size is small, the weight is light, and the efficiency is high,it also provides several functions such as over/under voltage protection in DC bus, soft start, detection of islanding operation and stand-alone operation. In the control system, the proposed PV system is decoupled into the phase-mode and neutral line-mode subsystems and accomplished by a digistal signal processor TMS320F240. Finally, a 1kVA experimental prototype is built to demonstrate the performance of the proposed technique.
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Lee, Yong Lung, and 李永龍. "Study and Implementation of the Multi-function Single-phase Three-wire Photovoltaic Energy Conversion System." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/68649302018689908335.
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碩士國立成功大學
電機工程學系
87
A single-phase three-wire multi-function photovoltaic(PV) energy conversion system is presented in this thesis. When the PV energy conversion system was operated at the maximum power point, the solar power supplied the required load energy and the surplus was fed to the utility with sinusoidal wave. The energy conversion system can be adapted as an active power filter(APF) at the low insolation condition. Besides, the neutral line current was controlled to regulate the line current in order to balance the phase voltage. In this thesis, a PV energy conversion system is constructed by single stage without extra storage devices-batteries, and used a three-leg converter to yield output without output transformer. So, the size is small, the weight is light, and the efficiency is high. The proposed PV system was decoupled into the common-mode subsystem and differential-mode subsystem to simplify the control process. Finally, a 1kVA experimental prototype was built to demonstrate the performance of the proposed technique.
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Lee, Szu-Hsien, and 李思賢. "DSP-Based Single Phase Small scale Photovoltaic Energy Conversion System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/49966159468801258435.
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碩士國立中山大學
電機工程學系研究所
91
This thesis proposes an implementation of a DSP-Based single-phase small-scale photovoltaic energy conversion system. The conversion system converts dc power generated by photovoltaic cells into ac power. A digital signal processor and a combined circuit with push-pull and full-bridge architectures are used in this study to reduce the complexity of the circuit design. Several operation and protection functions, such as maximum power point tracking, over/under voltage protection, over current protection, over/under frequency protection and detection of islanding operation are considered in the design. The operation performance of the conversion system at different stages is analyzed. The proposed conversion system can supply the local loads and feed excess power to the utility network with unit power factor (grid-connection mode), or it can supply loads exclusively (stand-alone mode). The simulation and experimentation results are presented and discussed to show the performance of the photovoltaic system and verify the feasibility of the proposed energy conversion system.
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Feng, Yung Ping, and 馮詠評. "Design of a Multi-Operating Mode Single Phase Photovoltaic Energy Conversion System." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/03640765926643235446.
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碩士長庚大學
電機工程學研究所
98
This thesis proposes a multi-operating mode single phase photovoltaic energy conversion system (PECS). As the PECS is operated at constant voltage mode (CVM), a simple protection mechanism is employed to detect system overloading such that power balance between solar irradiation and load can be guaranteed. For maximum power point tracking mode (MPPT), an optimal algorithm subjected to a sinusoidal output voltage was proposed to maximize the root-mean-square voltage and thereby giving the output voltage immunity from distortion. The problem caused by conventional MPPT for increasing output power but at the expense of the voltage quality can thus be improved. To investigate the performance of the proposed single phase PECS, the experimental setup, which is composed of a DSP-based control chip, 1.5kW monocrystalline silicon PV array, full bridge dc/dc converter and single phase current-sourced inverter (CSI), is developed. The experimental results show that the multi-operating mode PECS is capable of regulating output voltage at CVM and extracting maximum power from solar array at MPPT mode.
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Wei-ChunLin and 林偉群. "Design of Single Phase Photovoltaic Energy Conversion System and Digital Control Chip." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/15734040832507347977.
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碩士國立成功大學
電機工程學系碩博士班
101
In this thesis, a single phase photovoltaic energy conversion system and digital control chip are designed. The PV system includes a novel high step-up DC-DC converter and a full bridge inverter. The system transfers DC power generated by photovoltaic cells into AC power. The step-up converter is a current-fed type which makes input current ripple small. Because the leakage current is recycled, conduction loss is significantly decreased. With the FPGA controller, the converter possesses the MPPT control, and the inverter supports loads with real power to the utility by current mode control, or exclusively with 110V/60Hz sinusoidal voltage by voltage mode control. After the functions are verified, the control chip is designed with TSMC 0.18μm manufacturing process. Finally, the proposed PV system is implemented, and experimental results are provided to verify the performances of the system circuits and the control program.
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Kau, Ching-Fa, and 高進發. "Development of a Novel Control Strategy For Single-Phase Power Conversion Systems." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/17831248982589410058.
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Huang, Chung-Lun, and 黃崇倫. "Design and Implementation of Converter for Grid-Connected Single-Phase Photovoltaic Energy Conversion System." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/2y36bz.
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碩士國立雲林科技大學
電機工程系碩士班
96
This thesis presents the design and implementation of converters for the grid-connected single-phase photovoltaic energy conversion system. In order to provide the functions of the energy management and the load distribution, the system is combined with the photovoltaic cells and utility network. Due to that the output voltage and current of the photovoltaic cells are easily changed by light and load fluctuations, it will cause the maximum power points drift. Therefore, the maximum power point tracking and power electronic technique are required to draw the available maximum power from the photovoltaic cells. The proposed system makes use of the perturbation-and-observation method to achieve maximum power point tracking. The output frequency, phase and amplitude of the single-phase inverter are the same with utility network by using the zero-crossing control method. Therefore, it can match the condition of the grid-connected system. A digital signal processor is applied for the system control. Finally, a 500W generation system is constructed and tested to verify the system performance.
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Chen, Guan-Yu, and 陳冠宇. "Development of Grid-connected Single-phase Converter for Permanent-magnet Synchronous Motor Drives with Bidirectional Power Conversion." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/c9n6xw.
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碩士國立臺灣科技大學
電機工程系
107
This thesis aims to develop single-phase grid-connected three-phase permanent-magnet synchronous motor (PMSM) drives with bidirectional power conversion. The system includes single-phase inverter and PMSM drives. The single-phase full-bridge inverter with digital phase-lock loop control is adopted to trace the voltage phase angle immediately. The bidirectional power conversion control strategy with the power compensation method is introduced to improve the stability of dc-link voltage. The three-phase three-leg inverter with field-oriented control is used to control the speed, torque, and rotor position of three-phase PMSM. Moreover, the feedback of three-phase current and rotor position, obtained by current sensor and resolver, is used to enhance the motor operating performance. When the system is operated in motor mode, PMSM is under speed control and the power flow from single-phase grid side to motor side. When the system is operated in generator mode, PMSM is under torque control and the power flows from motor side to single-phase grid side. Therefore, braking resistors needn’t be added in dc-link. The mechanical energy is converted to electrical energy directly, yielding the energy recovery benefits. The digital signal processor, TMS320F28069, is adopted as system core. When the system is operated in motor mode at 2500 rpm with mechanical load of 4 N-m, the peak phase current and total harmonic distortion (THD) are 6.17A and 2.63%, respectively, the RMS voltage of the single-phase grid side is 220V. The RMS inductor current and its THD of the single-phase grid side are 5.31A and 3.68%. The dc-link voltage is 400V. The system efficiency is 79.1%. When the system is operated in generator mode at the same situation, the peak phase current and THD are 6.38A and 1.94%, respectively, the RMS inductor current and its THD of single-phase grid side are 4.26A and 3.94%. The system efficiency is 85.0%. When the system is operated in rotor position control mode at 4 N-m, the mechanical angle of 1080 degrees in clockwise and counterclockwise rotation are implement stably in 1.2s. In conclusion, the experimental results verify the feasibility of the system.
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Cao, Jhe-Wei, and 曹哲瑋. "Power Pulsation Decoupling and Power Control of a Single-Phase Voltage-Source Inverter for Renew Energy Conversion System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/04284784655505367345.
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碩士明志科技大學
電機工程系碩士班
102
This thesis developed a power control with a power pulsation compensation method for a single-phase grid-connected PV system. Use TI TMS320F28335 digital signal processor as the control center to build a digital phase-lock-loop (DPLL), power control, and power pulsation compensation. Based on the DPLL, the frequency, phase angle, and amplitude of the grid voltage are obtained by the second-order generalized integrator quadrature-signal generator (SOGI-QSG), synchronous frame conversion, and phase angle control loop. The DPLL can reduce the interference of the harmonics. Through the improved single-phase power control method proposed in this paper to control active power and reactive power ingredients which are injected into the grid system, the power factor and efficiency are improved, the current harmonics are reduced dramatically, and the power quality of the overall system is also enhanced. The output power of a single-phase voltage-source inverter has inherently twice frequency power pulsation that causes the output current distortion and reduces the utility of renew power module. The power pulsation is double the line frequency and no manipulation of switching frequency or inverter topology can reduce the energy requirements. In this work a power pulsation decoupling method is proposed by integrated with digital phase lock-loop, power control and a bi-direction buck-boost converter at dc side. Experimental results have demonstrated that the current produced by power pulsation is reduced dramatically and the output current of a renew energy module is almost constant.
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Xu, Xiangming. "Wafer-scale growth method of single-crystalline 2D MoS2 film for high-performance optoelectronics." Diss., 2020. http://hdl.handle.net/10754/666313.
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2D semiconductors are one of the most promising materials for next-generation electronics. Realizing continuous 2D monolayer semiconductors with single-crystalline structure at the wafer scale is still a challenge. We developed an epitaxial phase conversion (EPC) process to meet these requirements. The EPC process is a two-step process, where the sulfurization process was carried out on pre-deposited Mo-containing films. Traditionally, two-step processes for 2D MoS2 and other chalcogenides have suffered low-quality film and non-discontinuity at monolayer thickness. The reason was regarded as the low lattice quality of precursor film. The EPC process solves these problems by carefully preparing the precursor film and carefully controlling the sulfurization process. The precursor film in the EPC process is epitaxial MoO2 grown on 2″ diameter sapphire substrate by pulsed laser deposition. This epitaxial precursor contains significantly fewer defects compared to amorphous precursor films. Thus fewer defects are inherited by the EPC MoS2 film. Therefore, EPC MoS2 film quality is much better. The EPC prepared monolayer MoS2 devices to show field-effect mobility between 10 ~ 30 cm2·V-1s-1, which is the best among the two-step process. We also developed a CLAP method further to reduce the defects in the precursor oxide film; thus, in-plane texture in the thicker MoS2 film was eliminated, and a single-crystalline structure was obtained in the wafer-scale MoS2 films. The potentially feasible technique to further improve the 2D film quality is pointed out for our next research plan. Meanwhile, the epitaxial phase conversion process was proposed to be as a universal growth method. Last but not least, we demonstrate several potential applications of the wafer-scale single-crystalline MoS2 film we developed, such as logic circuits, flexible electronics, and seeding layer of van der Waal or remote epitaxial growth.
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Gorzkowski, Edward P. "The effect of liquid phase chemistry on growth of lead magnesium niobate-lead titanate single crystals by seeded polycrystal conversion /." Diss., 2004. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3127523.
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Lin, Wu-Hung, and 林悟宏. "DSP-based Three-phase Three-wirePhotovoltaic Energy Conversion System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/676xwj.
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碩士國立成功大學
電機工程學系碩博士班
90
A DSP-based digital controlled three-phase three-wire grid-connected multi-function photovoltaic energy conversion system is presented in this thesis. The photovoltaic energy conversion system is constructed by a three-leg inverter without storage device-batteries and output transformer. Therefore, the size is small, the weight is light, and the efficiency is high. The system also provides several functions such as over/under voltage protection in DC bus, detection of islanding operation, and stand-alone operation. Besides, the protecting functions of a grid-connection photovoltaic inverter system are included in the system to prevent the islanding effect. The three-leg voltage-fed inverter is operated at the current mode when the conversion system is operated at grid-connection mode. Thus, the system can supply real power to loads and feed excess power to the utility with unit power factor. As the conversion system is operated at the stand-alone mode, the output voltage is modulated to supply sinusoidal voltage to the loads. Finally, a 1kVA experimental prototype is built to demonstrate the performance of the proposed technique.
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Nesbitt, James William. "A novel single phase to three phase converter." 1990. http://catalog.hathitrust.org/api/volumes/oclc/23057889.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1990.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 67).
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Chen, Guan-Ying, and 陳冠穎. "A Novel Single-stage Single-phase AC to Three-phase AC Converter." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/7dv95n.
Full textAbstract:
碩士國立虎尾科技大學
電機工程研究所
100
This thesis proposes a novel single-stage single-phase AC to three-phase AC converter. Based on a zero vector technique, the proposed converter combines a single-phase full-bridge with three-phase full-bridge to form a single-stage circuit structure. The converter has unity power factor and sinusoidal input current in input side. Adjustable amplitude and frequency of three-phase current source are in output side. The proposed converter consists of eight power switches, one capacitor, one boost inductor and three output inductors. It’s worth mentioning that ten switches of the traditional converter can reduce to eight, and this can reduce cost and improve efficiency obviously. Besides, general solution of the switching duty ratio is obtained by using the state space averaging technique. Furthermore, employing the three-phase dead-band control can decrease the ratio of 1/3 times switching number. Consequently, this reduce the switching loss, and improves efficiency of the converter. In the control circuit, both VisSim simulation and DSP TMS320F2812 are employed to finish digital control for power factor correction of the input side and feedback control of the output side. Finally, some experiment results are presented to verify the feasibility of the proposed converter.
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Huang, Kuo-Fung, and 黃國芳. "Study of Three-Phase Input Single-Phase Output Uninterruptible Power System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/72813291767985353156.
Full textAbstract:
碩士國立高雄應用科技大學
電機工程系
98
Three-phase four-wire distribution power systems have been widely applied in office buildings and manufacturing-office buildings to supply single-phase or three-phase loads. The uninterruptible power supply (UPS) is generally applied to supply the high quality power to the computer and precise equipment. In this thesis, three-phase input single-phase output UPS, composed of three-phase AC-DC power converter, battery set and single-phase DC-AC inverter, is addressed. Several circuit topologies and control methods, applied for the power factor correction, are analyzed, and the advanced two switches based power factor correction circuit with a new power factor correction method is proposed and implemented in the three-phase AC-DC power converter. The three-phase input currents of proposed three-phase AC-DC power converter are balanced, sinusoidal and in phase with the three-phase utility voltages so as to perform the unity power factor. The single-phase DC-AC inverter is configured by a diode-clamped three-level inverter to generate a high quality voltage to the load regardless the utility is normal or not. Finally, the computer simulation is made to verify the performance of proposed UPS. The simulation results show the performance of proposed three-phase input single-phase output UPS is as expected.
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Chung, Bing-hsueh, and 鍾秉學. "Development of Single-Phase and Three-Phase Grid-Connected Power Converters." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/n3aapn.
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碩士國立臺灣科技大學
電機工程系
99
This thesis is concerned with the analysis and implementation of single-phase and three-phase dc-ac power converters for grid-connection. The utility angle is used to calculate the digital phase-locked loop in the single-phase and three-phase dc-ac power converters. The controllers, which use the d-q current control modes, are performed under stationary frame, thereby yielding current and power stably to utility. In the stand-alone system, the single-phase ac voltage regulator and voltage feed-forward compensation are introduced to improve response and reduce the steady-state error. Whereas three-phase stand-alone system uses the voltage control strategy to control the output voltage to follow the balanced command voltage. The overall system for performance evaluation includes wind generator and islanding detection. When utility power fails, the system switches to stand-alone mode and continues to supply power to ac load reliably. In this thesis, the mathematical models of single-phase and three-phase dc-ac power converter systems are built and simulated by Matlab/Simulink. Then, a high-performance digital signal processor, TMS320F28335, is used to control the system with the voltage and current feedbacks. The control of overall system is conducted by software to reduce circuit component and improve system reliability. A prototype of 1kW power conversion system is developed. Under single-phase and three-phase grid-connected operations, the output voltage is 110V, 60Hz. Besides, the experimental data show that the current total harmonic distortion measured is less than 5% with efficiency above 90%.
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Hedayati, Mohammad Hassan. "Integrated CM Filter for Single-Phase and Three-Phase PWM Rectifiers." Thesis, 2015. http://etd.iisc.ernet.in/2005/3947.
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The use of insulated-gate bipolar transistor (IGBT)-based power converters is increasing exponentially. This is due to high performance of these devices in terms of efficiency and switching speed. However, due to the switching action, high frequency electromagnetic interference (EMI) noises are generated. Design of a power converter with reduced EMI noise level is one of the primary objectives of this research.
The first part of the work focuses on designing common-mode (CM) filters, which can be integrated with differential-mode (DM) filters for three-phase pulse-width modulation (PWM) rectifier-based motor drives. This work explores the filter design based on the CM equivalent circuit of the drive system. Guidelines are provided for selection of the filter components. Different variants of the filter topology are evaluated to establish the effectiveness of the proposed topology. Analytical results based on Bode plot of the transfer functions are presented, which suggest effective EMI reduction. Experimental results based on EMI measurement on the grid side and CM current measurement on the motor side are presented. These results validate the effectiveness of the filter.
In the second part of the work, it is shown that inclusion of CM filters into DM filters results in resonance oscillations in the CM circuit. An active damping strategy is proposed to damp the oscillations in both line-to-line and line-to-ground ac voltages and currents. An approach based on pole placement by state feedback is used to actively damp both the DM and CM filter oscillations. Analytical expressions for state-feedback controller gains are derived for both continuous-and discrete-time models of the filter. Trade-off in selection of the active damping gain on the lower-order grid current harmonics is analysed using a weighted admittance function method.
In the third part of the work, single-phase grid-connected power converters are considered. An integrated CM filter with DM LCL filter is proposed. The work explores the suitability of PWM methods for single-phase and parallel single-phase grid-connected power converters. It is found that bipolar PWM and unipolar PWM with 180◦interleaving angle are suitable for single-phase and parallel single-phase power converters, respectively. The proposed configuration along with the PWM methods reduces the CM voltage, CM current, and EMI noise level effectively. It is also shown that the suggested circuit is insensitive to nonidealities of the power converter such as dead-time mismatch, mismatch in converter-side inductors, unequal turn on and turn off of the switches, and propagation delays.
In the fourth part of the work, the inter-phase inductor in parallel interleaved power converters is integrated with LCL filter boost inductor. Different variant designs are presented and compared with the proposed structure. It is shown that the proposed structure makes use of standard core geometries and consumes lesser core material as well as copper wire. Hence, it reduces the overall size and cost of the power converter.
In the present work, a 10kVA three-phase back-to-back connected with input LCL filter and output dv/dt filter, a 5kVA single-phase grid-connected power converter with LCL filter, and a 7.5kVA parallel single-phase grid-connected power converter with LCL filter are fabricated in the laboratory to evaluate and validate the proposed methods. The experimental results validate the proposed methods that result in significant EMI performance improvement of grid-connected power converters.
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Wei-ChengChen and 陳威呈. "Single-Stage Three-Phase CCM Wind-Power Converter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/v6gn8t.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
101
This thesis presents a single-stage three-phase CCM wind-power converter. In order to achieve both maximum-power-point-tracking (MPPT) and three-phase power-factor-correction (PFC) mechanisms, two stages are employed in the conventional wind energy conversion system (WECS). However, the two-stage system results in some drawbacks, including larger volume, more components, higher circuit cost, more complicated control scheme and lower system efficiency. Therefore, the proposed converter of this thesis is developed to avoid these problems and increase the electromechanical conversion efficiency of the wind turbine generator (WTG), the MPPT and three-phase PFC mechanisms are employed simultaneously. In the proposed circuit, a three-phase PFC converter and an average-current-mode control (ACMC) scheme are utilized to improve the power factor of the converter for the WEC. Besides, according to the characteristics of the WTG, the output voltage, current, and power of the WTG can be operated at MPP for each wind speed by using the ACMC scheme and subtracting amplifier. In this thesis, a wind turbine emulator (WTE) is used as the AC source for the proposed circuit with the emulated wind speed ranging from 5m/s to 9m/s. The lowest and highest powers at MPP of the WTE are 185W and 1079W, respectively. Finally, a prototype circuit of the single-stage three-phase CCM wind-power converter is built to verify the performances using MPPT and three-phase PFC mechanisms.