Dissertations / Theses on the topic 'Equivalent electrical circuit model'
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Danielsson, Christer. "Analysis of Synchronous machine dynamics using a novel equivalent circuit model." Licentiate thesis, Stockholm : Skolan för elektro- och systemteknik, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10510.
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Abubakar, Hadiza Ahmad. "Investigating ageing behaviours in supercapacitor (cells and modules) using EEC (electrical equivalent circuit) models." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/41066/.
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This thesis contributes to the reliability and aging studies of supercapacitors for more efficient use in EV/HEV applications. This thesis demonstrates the effect of aging/failure in supercapacitor cells and module cells using accelerated tests employed to expedite the aging process. The tests, as explained below were categorized based on operational and environmental aging factors associated with supercapacitor failure in EV/HEV applications to; • Investigate supercapacitor cell performance at high temperature and constant voltage individual conditions, and also simultaneously (known as calendar test) • Investigate the effect of voltage balancing/equalization circuits on supercapacitor module cells’ performance during constant current cycling tests under certain environmental and electrical factors • Investigate supercapacitor module cells’ cycling performance in a lab-scale designed electrical DC programmable motor load system that emulates supercapacitor operational conditions in an EV/HEV application. The aging behaviors characterized by the three factors mentioned above are quantified in this thesis through the periodic monitoring of their electrical and electrochemical state of health with Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, and Constant Current characterization tests. These tests help identity aging modes in supercapacitors, and it was observed that regardless of their aging factors; an increase in ESR and decrease of capacitance was determined. Although this information is required, the results from Electrochemical Impedance Spectroscopy (EIS) tests revealed more details distinctive to each aging factor. From this distinction, the aging mechanisms in relation to the aging factors, which causes the deterioration in the supercapacitor electrical performance, are identified and summarized as the following: 1. Loss of contact within supercapacitor electrode, given rise to the contact resistance due to the presence of high temperature as the main aging factor 2. Change of supercapacitor porous electrode emulating a charge transfer reaction thereby increasing its distributed resistance, caused by the effect of high voltage or cycling Mathematical models in the form of electrical equivalent circuits (EECs) distinctive of their aging factors are generated from EIS electrochemical behaviors to easily describe aging behaviors in supercapacitors. The EEC models developed using impedance modeling generated an initial model from dormant cells, which transitioned to aging models distinctive of their aging factors as soon as a 100% increase in ESR and/or an 80% decrease in capacitance is observed. The proposed EEC models were validated to show the dynamic interaction between aging of the supercapacitor cells on their electrical performance in both frequency and time domains. In summary, the EEC models encompass this thesis objective and as such considered the main contribution of this research work.
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Hasan, Samil Muklisin Yauma. "Characterization of high-speed electronic packages using reduced-order partial element equivalent circuit models." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/283989.
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Two circuit model extractors for complex multilayer microelectronic packages based on the Partial Element Equivalent Circuit (PEEC) technique, namely University of Arizona Effective Package Inductance Calculator (UAEPIC) and University of Arizona Effective Package Inductance and Capacitance Calculator (UAEPIC²), have been developed. The first one, UAEPIC, is based on the magneto-quasistatic assumption where the displacement current effect on the derivation of the electromagnetic field integral equation is neglected and thus the dominant inductive effects are modeled in order to extract the RL equivalent model. The second one, UAEPIC², uses a more rigorous electromagnetic model that accounts for displacement (yet nonretarded) electromagnetic effects to extract the RLC equivalent model of the given microelectronic package. The development of electrical models of packages of high complexity requires the numerical solution of linear systems of several thousands of equations. This makes the development of a broadband equivalent circuit to include skin effect computationally expensive. To circumvent this difficulty, two model order reduction techniques have been utilized. The method of Asymptotic Waveform Evaluation (AWE) has been incorporated in UAEPIC, and the Passive Reduced-order Interconnect Macromodeling Algorithm (PRIMA) has been applied to UAEPIC². Applications of AWE and PRIMA provide orders of magnitude reduction in computation labor and lead to a direct multiport Y-matrix representation in terms of the poles and residues. In this form, and using a special algorithm, the multiport, frequency-dependent equivalent circuit of the package can be incorporated efficiently in a SPICE-like circuit simulator. This simulation capability facilitates rapid and accurate simulations for the analysis of noise generation and signal degradation such as delay, cross-talk, power and ground bounces, and Simultaneous Switching Noise (SSN) in the package.
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Sugden, Frank Daniel. "A NOVEL DUAL MODELING METHOD FOR CHARACTERIZING HUMAN NERVE FIBER ACTIVATION." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1318.
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Presented in this work is the investigation and successful illustration of a coupled model of the human nerve fiber. SPICE netlist code was utilized to describe the electrical properties of the human nervous membrane in tandem with COMSOL Multiphysics, a finite element analysis software tool. The initial research concentrated on the utilization of the Hodgkin-Huxley electrical circuit representation of the nerve fiber membrane. Further development of the project identified the need for a linear circuit model that more closely resembled the McNeal linearization model augmented by the work of Szlavik which better facilitated the coupling of both SPICE and COMSOL programs. Related literature was investigated and applied to validate the model. This combination of analysis tools allowed for the presentation of a consistent model and revealed that a coupled model produced not only a qualitatively comparable, but also a quantitatively comparable result to studies presented in the literature. All potential profiles produced during the simulation were compared against the literature in order to meet the purpose of presenting an advanced computational model of human neural recruitment and excitation. It was demonstrated through this process that the correct usage of neuron models within a two dimensional conductive space did allow for the approximate modeling of human neural electrical characteristics.
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Liu, Xing, and s3072856@student rmit edu au. "Electrical Impedance Spectroscopy Applied in Plant Physiology Studies." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080428.092529.
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Electrical Impedance Spectroscopy (EIS) is a relatively new method applied to food quality assessment. EIS allows relatively inexpensive assessment, is fast, easy to operate and non-invasive. It has been adopted for investigation of fundamental electrical properties of plant tissues. Although the applications of EIS for food quality determination have been reported previously, the analytical relationships between electrical impedance properties and quality criteria have not yet been fully developed. Further exploration is thus important in acquiring more data on electrical impedance characteristics of fruits and vegetables and researching new approaches for determination of their quality. This dissertation aims to investigate the electrical impedance properties of fruits and vegetables, and explore the relationship between impedance and quality criteria. In particular, the present dissertation outlines experimental research conducted on relationships between impedance properties and fruit tastes as well as the impedance changes observed during ripening process. Impedance measurement to monitor moisture content changes in the progress of drying is also included in this research. In summary, the impedance properties have merits in fruits and vegetables quality assessment. The current used subjective visual inspection and assessment could be replaced by the EIS based approach as it is a more precise measurement of food quality. Further study is required to give this method practical value.
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Esfahani, Pedram. "A Study of the Frequency Dependence of Permittivity and Permeability in Lossless One-Dimensional Composite Right/Left Handed Metamaterials by the Equivalent Circuit Model." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468524947.
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Traub, Felix Maximilian [Verfasser], Thomas [Akademischer Betreuer] Weiland, and Albert [Akademischer Betreuer] Ruehli. "Automated Construction of Equivalent Electrical Circuit Models for Electromagnetic Components and Systems / Felix Maximilian Traub. Betreuer: Thomas Weiland ; Albert Ruehli." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2014. http://d-nb.info/1108094988/34.
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Shamsi, Mohammad Haris. "Analysis of an electric Equivalent Circuit Model of a Li-Ion battery to develop algorithms for battery states estimation." Thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-298427.
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Batteries have imparted momentum to the process of transition towards a green future. However, mass application of batteries is obstructed due to their explosive nature, a trait specific to Li-Ion batteries. To cater to an efficient battery utilization, an introduction of a battery management system would provide an ultimate solution. This thesis deals with different aspects crucial in designing a battery management system for high energy as well as high power applications. To build a battery management system capable of predicting battery behavior, it is necessary to analyze the dynamic processes happening inside the battery. Hence, a battery equivalent circuit model is proposed in this thesis as well as proper analysis is done in MATLAB to project a generic structure applicable to all Li-Ion chemistries. The model accounts for all dynamic characteristics of a battery including non-linear open circuit voltage, discharge current and capacity. Effect of temperature is also modeled using a cooling system. The model is validated with test current profiles. Less than 0.1% error between measured and simulated voltage profiles indicates the effectiveness of the proposed model to predict the runtime behavior of the battery. Furthermore, the model is implemented with the energy as well as the power battery pack. State of charge calculations are performed using the proposed model and the coulomb counting method and the results indicate only a 4% variance. Therefore, the proposed model can be applied to develop a real-time battery management system for accurate battery states estimation.
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Tondo, Felipe Augusto. "Identificação e análise da função de transferência do circuito equivalente de um sistema de medição por correntes parasitas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/156486.
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Este trabalho apresenta o estudo de um sistema genérico de medição que utiliza o princípio das correntes de Foucault, comumente conhecidas como correntes parasitas. O modelo do sistema é representado como um circuito elétrico equivalente composto por R1 e L1, respectivamente caracterizando a resistência e a indutância do circuito primário, as quais são conhecidas por uma bobina de excitação. Já no secundário, R2 e L2, estão representando a perda ôhmica e a indutância da amostra no qual as correntes parasitas são induzidas, além de outros dois componentes, M indutância mútua dos indutores acoplados e k, coeficiente relacionado ao acoplamento magnético entre os circuitos primário e secundário. A análise tradicionalmente utilizada para este tipo de medição é a avaliação da reflexão da impedância equivalente do circuito secundário representando a amostra no circuito primário. O trabalho analisa as equações de malha do circuito equivalente no domínio da frequência e identifica os parâmetros do modelo. A partir da identificação do sistema realizada com os ensaios experimentais, foi possível descobrir a constante de tempo indutiva τL do sistema. A partir dessa constante, observou-se a variação acentuada da mesma em relação a variação da impedância equivalente. Ainda é apresentada uma estimativa dos valores de R2 e L2 realizada por meio da unificação das informações obtidas com a identificação, aliada com as informações de campo magnético obtidas a partir de um sensor do tipo GMR e pela simulação em um software de elementos finitos COMSOL Multiphysics.This work presents the study of a generic measurement system that uses the prin- ciple of eddy currents. The system model is represented as an equivalent electric circuit composed of R1 and L1 respectively characterizing the resistance and induc- tance of primary circuit, which are known by an excitation coil. In the secondary, R2 and L2 are representing the ohmic loss and the inductance of the sample in which the eddy currents are induced, in addition two other components, the mutual induc- tance of the coupled inductors and k, coefficient related to the magnetic coupling between the primary and secondary circuits. The analysis traditionally used for this type of measurement is the reflection evaluation of the equivalent impedance of the secondary circuit representing the sample in the primary circuit. The work analyzes the mesh equations of the equivalent circuit in the frequency domain and identifies the parameters of the model. From the identification of the system performed with the experimental tests, it was possible to discover the inductive time constant τL of the system. From this constant, it was observed the sharp variation of the same in relation to the variation of equivalent impedance. An estimate values, R2 and L2 performed by unification of the information obtained with the identification, to- gether with the magnetic field information obtained from a GMR type sensor and by simulation in a finite element software COMSOL Multiphysics.
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Sundararajan, Arjun. "Development of a Computer Model to Simulate Battery Performance For Use In Renewable Energy Simulations." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1622589070614764.
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Bourjilat, Ayoub. "Étude et conception d’une plateforme microfluidique pour la détection de séquence ADN par spectroscopie d’impédance." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0343/document.
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L’objectif de cette thèse est la conception de biocapteurs capables de détecter la présence de séquences d’ADN sans utilisation de marqueurs chimiques ou de traitement préalable de l’échantillon. Le principe de mesure utilise la spectroscopie d’impédance pour la détection du changement provoqué par la présence de la séquence ADN sur le biocapteur. Notre étude s’appuie sur des simulations analytiques et numériques pour définir les dimensions des capteurs adaptés aux mesures en basse fréquence ainsi que le développement d’un modèle de circuit équivalent qui prend en considération les effets d'interfaces. La fabrication du capteur a été réalisée en plusieurs étapes. Dans un premier temps, la conception et la fabrication en salles blanches ont été optimisées pour des structures interdigitées avec différentes géométries et différents types de substrat (Verre, Si, SiO2). Après la validation du modèle, par des mesures sur des solutions de conductivité étalon et sur plusieurs concentrations d’ADN, l’analyse des résultats nous a conduits à proposer une nouvelle structure à électrodes concentriques mieux adaptée aux mesures d’impédance en basses fréquences pour des milieux liquides. Deux prototypes de taille micrométriques, l’un à électrode interdigitée et l’autre à électrode concentrique ont été développés pour une étude comparativeThe objective of this thesis is the conception of a biosensor able to detect the presence of DNA sequences without any use of chemical markers or a prior treatment of the samples. The measurements are performed using impedance spectroscopy technique to detect the changes caused by the presence of DNA sequences on the biosensor. Our study is based on analytic and numeric simulations, which allows us to define the dimensions of the sensors adapted to low frequency measurements and to propose an equivalent circuit model taking into account the effects of the electrical double layer. The sensor was manufactured in several steps. Initially, clean room design and manufacturing were optimized for interdigitated structures with different geometries and substrate types (Glass, Si, SiO2). The data analysis of the measurement on standard conductivity and on several DNA concentrations using interdigitated electrode biosensor, allows us to propose a new design with concentric electrodes which is more adapted to low frequency impedance measurement according to a comparative study between interdigitated and concentric electrodes
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Chaiwan, Pramote. "NEW ACCURATE FAULT LOCATION ALGORITHM FOR PARALLEL TRANSMISSION LINES." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/813.
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Electric power systems have been in existence for over a century. Electric power transmission line systems play an important role in carrying electrical power to customers everywhere. The number of transmission lines in power systems is increasing as global demand for power has increased. Parallel transmission lines are widely used in the modern transmission system for higher reliability. The parallel lines method has economic and environmental advantages over single circuit. A fault that occurs on a power transmission line will cause long outage time if the fault location is not located as quickly as possible. The faster the fault location is found, the sooner the system can be restored and outage time can be reduced.
The main focus of this research is to develop a new accurate fault location algorithm for parallel transmission lines to identify the fault location for long double-circuit transmission lines, taking into consideration mutual coupling impedance, mutual coupling admittance, and shunt capacitance of the line.
In this research, the equivalent PI circuit based on a distributed parameter line model for positive, negative, and zero sequence networks have been constructed for system analysis during the fault. The new method uses only the voltage and current from one end of parallel lines to calculate the fault distance. This research approaches the problem by derivation all equations from positive sequence, negative sequence, and zero sequence network by using KVL and KCL. Then, the fault location is obtained by solving these equations. EMTP has been utilized to generate fault cases under various fault conditions with different fault locations, fault types and fault resistances. Then the algorithm is evaluated using the simulated data. The results have shown that the developed algorithm can achieve highly accurate estimates and is promising for practical applications.
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Sergent, Aaronn. "Optimal Sizing and Control of Battery Energy Storage Systems for Hybrid-Electric, Distributed-Propulsion Regional Aircraft." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595519141013663.
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Sutliff, Robert William. "The Effects of Loading on Equivalent Electric Circuit Models for Piezoelectric Transducers." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1533304929347075.
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Kuparowitz, Tomáš. "Transport a ukládání náboje ve struktuře superkondenzátoru." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-364610.
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Práce se zabývá studiem superkondenzátorů (SC). Výstupem je detailní studie principů přenosu náboje ve struktuře SC, ukládání energie a nový náhradní model SC, který je založen na fyzikálních zákonitostech a principech SC. Dále byl vytvořen matematický model SC, který popisuje chování náboje v jeho aktivní vrstvě. SC byly testovány metodami umělého stárnutí. Závislosti poklesu parametrů SC vlivem různých metodik stárnutí jsou v práci shrnuty.
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Amani, Julian Alexander [Verfasser], Hans Christian [Akademischer Betreuer] [Gutachter] Hofsäss, Michael [Gutachter] Seibt, and Ørjan G. [Gutachter] Martinsen. "A novel approach of immittance-spectra analysis and how it resolves a decade-old deviation of the Frenkel-Poole model : Utilising process-specific physical models to find the electrical equivalent circuit representing the underlying physics in immittance spectroscopy / Julian Alexander Amani ; Gutachter: Hans Christian Hofsäss, Michael Seibt, Ørjan G. Martinsen ; Betreuer: Hans Christian Hofsäss." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1126248576/34.
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Hedon, Martin. "Modeling and Simulation of a Hybrid Powertrain." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-235271.
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Hybrid powertrains represent the current trend on passenger cars. The purpose of thisreport is to create a basic model of a hybrid powertrain in Matlab/Simulinkenvironment and study their performance over certification driving cycle. Threecommonly used architectures are modeled and discussed in Simulink. Hence, the basiccomponents of a powertrain – battery, electric machine and combustion engine – arestudied and basic models are realized. A Thevenin equivalent circuit is used to simulatethe behavior of the battery, and the combustion engine is modeled after a Willansmodel. The electric machine model is based on a known efficiency map. Then, thearchitectures are created as well as their control strategies. The control strategies arecreated through state diagrams, and implemented into the Simulink model viaStateflow charts. A validation procedure is presented in order to study the consistencyof the models.Hybrid drivlinor representerar en central personbilstrend. Syftet med rapporten är attpresentera en grundläggande modell för en hybrid drivlina i Matlab/Simulink. Trearkitekturer behandlas och har implementerats i Simulink. Sedan studeras degrundläggande komponenterna i ett drivaggregat (batteri, elmaskin ochförbränningsmotor). En Thevenin-ekvivalent krets används för att simulera batterietsbeteende. Förbränningsmotorn är modellerad efter en Willans-modell.Elmaskinmodellen är baserad på en känd verkningsgradsmapp. De tillhörandestyrstrategierna med hjälp av tillståndsdiagram. De implementeras i Simulinkmodellenmed hjälp av Stateflow-diagram. Ett valideringsförfarande presenteras ochvisar modellernas konsistens.
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Jin, Won Tae. "Circuit models for a millimeter-wave suspended-microstrip line discontinuity." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA240906.
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Thesis (M.S. in Systems Engineering (Electronic Warfare))--Naval Postgraduate School, September 1990.Thesis Advisor(s): Atwater, Harry A. Second Reader: Janaswamy, Rama. "September 1990." Description based on title screen as viewed on December 29, 2009. DTIC Identifier(s): Suspended striplines, microstrip lines, equivalent circuits, program listings, theses. Author(s) subject terms: Suspended-microstrip line, step discontinuity, equivalent circuit model, step-change. Includes bibliographical references (p. 60). Also available in print.
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Humphrey, Dave. "Equivalent circuit model of a prestressed concrete pressure pipe." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0004/MQ42634.pdf.
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Hai, Ling. "Modelling Wave Power by Equivalent Circuit Theory." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-265270.
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The motion of ocean waves can be captured and converted into usable electricity. This indicates that wave power has the potential to supply electricity to grids like wind or solar power. A point absorbing wave energy converter (WEC) system has been developed for power production at Uppsala University. This system contains a semi-submerged buoy on the water surface driving a linear synchronous generator placed on the seabed. The concept is to connect many small units together, to form a wave farm for large-scale electricity generation. A lot of effort has gone into researching how to enhance the power absorption from each WEC unit. These improvements are normally done separately for the buoy, the generator or the electrical system, due to the fact that modelling the dynamic behavior of the entire WEC system is complicated and time consuming. Therefore, a quick, yet simple, assessment tool is needed. This thesis focuses on studying the use of the equivalent circuit as a WEC system modelling tool. Based on the force analysis, the physical elements in an actual WEC system can be converted into electrical components. The interactions between the regular waves, the buoy, and the Power Take-off mechanism can be simulated together in one circuit network. WEC performance indicators like the velocity, the force, and the power can be simulated directly from the circuit model. Furthermore, the annual absorbed electric energy can be estimated if the wave data statistics are known. The linear and non-linear equivalent circuit models developed in this thesis have been validated with full scale offshore experimental results. Comparisons indicate that the simplest linear circuit can predict the absorbed power reasonably well, while it is not so accurate in estimating the peak force in the connection line. The non-linear circuit model generates better estimations in both cases. To encourage researchers from different backgrounds to adapt and apply the circuit model, an instruction on how to establish a non-linear equivalent circuit model is supplied, as well as on how to apply the model to accelerate the decision making process when planning a WEC system.
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Angel, Nathan A. "EQUIVALENT CIRCUIT IMPLEMENTATION OF DEMYELINATED HUMAN NEURON IN SPICE." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/611.
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This work focuses on modeling a demyelinated Hodgkin and Huxley (HH) neuron with Simulated Program with Integrated Circuit Emphasis (SPICE) platform. Demyelinating disorders affect over 350,000 people in the U.S and understanding the demyelination process at the cellular level is necessary to find safe ways to treat the diseases [9]. Utilizing a previous SPICE model of an electrically small cell neuron developed by Szlavik [32], an extended core conductor myelinated neuron was produced in this work. The myelinated neuron developed has seven active Nodes of Ranvier (nodes) separated by a myelin sheath. The myelin sheath can be successfully modeled with a resistive and capacitive network known as internodes. Both the Nodes of Ranvier and internode equivalent circuits were implemented in P-SPICE sub-circuit library files. Properties of the neuron can be changed in the library files to simulate neurons of different electrical or geometric properties. Using the P-SPICE code developed in this work, a myelinated neuron’s action potential was simulated and the action potential at each node was recorded. The action potential at each node was uniform in amplitude and pulse width. The conduction velocity of the action potential was calculated to be 57.15 m/s.
Demyelination can be modeled by decreasing the capacitance and increasing the resistance of the myelin [34]. Two demyelinated neuron models were simulated in this work. The first model had one internode segment demyelinated, and the second model was of three consecutive internode segments. The resulting conduction velocity was calculated for both simulations. For one and three internode segment demyelinated the conduction velocity was slowed to 44.15 m/s, and 27.15 m/s respectively. This model successfully showed that an HH neuron implemented in SPICE could show the effects of demyelination on conduction velocity
The goal of this work is to develop a demyelinated neuron so that treatments for Multiple Sclerosis (MS) and other demyelinated neurons could be simulated to test various treatments’ effectiveness. A current treatment for MS is ion channel blockers. Future work would be to use this model to test current ion channel blocker therapy and to validate if such therapies alleviate conduction slowing.
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Yan, Yingyi. "Equivalent Circuit Model for Current Mode Controls and Its Extensions." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50485.
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Current-mode control architectures have been an indispensable technique in many applications, such as Voltage Regulator, Point-of-load converters, power factor correction, battery charger and LED driver. Since the inductor current ramp is used in the modulator in current-mode control without any low pass filter, high order harmonics play important role in the feedback control. This is the reason for the difficulty in obtaining the small-signal model for current-mode control in the frequency domain. A continuous time domain model was recently proposed as a successful model for current-mode control architectures. However, the model was derived by describing function method, which is very arithmatically complicated, not to mention time consuming.For the analysis and design of non-linear system, equivalent circuit model, which is user friendly and intuitive, is an effective tool. In this dissertation, the primary objective is to develop a unified three-terminal switch model for current-mode controls using the results of describing function derivation, which characterizes the small signal property of the common subcircuit of current mode controlled PWM converters. Its application is extended to average current mode control, V2 control and other proposed novel current mode control schemes.
First, the existing model for current mode control is reviewed. The limitations of exsiting model for current-mode control are identified. Based on the universal small signal relationship between terminal currents and the results of describing function derivation, a unified three-terminal switch model for current mode control is proposed. A three-terminal equivalent circuit is developed to represent the small signal behavior of this common sub-circuit. The proposed model is applicable in both constant frequency and variable frequency modulation.
After that, the modeling of digital predictive current mode control is presented. Predictive current mode control is one of the promising digital current mode control method featuring fast dynamic response and low sample rate requirement. Many implementations were presented in past ten years. To understand the benefit and the limitation of each implementation, help the engineer to choose the modulation scheme and design the control loop, a small signal Laplace-domain model for digital predictive current mode controls is proposed. The model is extended to the multi-sampled implementation. The modeling result is summarize as the small signal equivalent circuit mode, whose form is consistant with that of analog current mode controls. Based on S-domain model, digital predictive current mode controls are compared with analog implementation to demonstrate the advantages and limitation. Implementation selection guideline and compensation is discussed based on the modeling results.
Then, using the proposed unified model is used in the analysis of average current mode control. Under proper design, the inductor current ripple passes through the current compensator and appears in PWM comparator. It significantly influence the high frequency small signal property of the converter. In chapter 3, the proportional feedback is separated from integral feedback so that the sideband frequency feedback effect can be taken into consideration. It extends the results obtained in peak-current model control to average current mode control. The proposed small signal model is accurate up to half switching frequency, predicting the sub-harmonic instability. Based on the proposed model, a new feedback design guideline is proposed. By designing the external ramp following the proposed design guideline, quality factor of the double poles at half of switching frequency in control-to-output transfer function can be precisely controlled. This helps the feedback design to achieve widest control bandwidth and proper damping.
V2 control is a popular control scheme in Point-of-load converters due to the unique fast transient response. As the output voltage ripple is used as PWM modulation ramp, V2 control has close relationship with current mode control but this relationship was not addressed in the exsiting model. Chapter 4 utilizes the three-terminal switch model to build the equivalent circuit model for V2 control, which clearly shows that V2 control is a particular implementation of current mode control, with proportional capacitor voltage feedback and load current feedback embeded.
The analysis presented in Chapter 3 provides a clear physical understanding of average current mode control. With constant frequency modulation, the control bandwidth is usually limited by the double pole at half of swithcing frequency, especially in the converters with wide duty cycle range. Chapter 5 proposed a novel I2 current mode control to improve the dynamic performance of average current mode control. In particular, constant on-time I2 control eliminates the need of external ramp while the current loop is inherently stable. Moreover, constant on-time modulation improves the light load efficiency.
As a conclusion, this dissertation proposed a unified three-terminal switch model for current mode controls. The application of this equivalent circuit model is extended to average current mode control, V2 control and the novel I2 current mode control. The Laplace-domain model of predictive current mode control is also presented. All the modeling results are verified through simulation and experiments.
Ph. D.
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Tian, Shuilin. "Equivalent Circuit Model of High Frequency PWM and Resonant Converters." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/56676.
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Distributed power system (DPS) is widely adopted in Power supplies for the telecom, computer and network applications. Constant on-time current mode control and V2 control are widely used as point-of-load (POL) converters and voltage regulators (VR) in DPS systems. Series resonant converters (SRC) are widely used in aerospace systems and LLC resonant converters are widely used as Front-end converters in DPS systems. The technological innovations bring increasing demand for optimizing the dynamic performance of the switching regulators in these applications. There has been a strong desire to develop simple and accurate equivalent circuit models to facilitate the design of these converters.
Constant on-time current-mode control has been widely used in POL and VRM converters. For multi-phase application, external ramp is required to improve jittering performance using pulse distribution method. Chapter II analyzes the effect of external ramp on small-signal model of constant on-time current mode control. It is found that external ramp brings additional dynamics by introducing a moving pole and a static zero. Next, a three-terminal switch model is proposed based on non-ideal current source concept, where the non-idealness of the current source is presented by a Re2-Le2 branch. Based on the proposed model, design guidelines are proposed based on either worst case design strategy or auto-tuning strategy.
V2 control has advantages of simple implementation and fast transient response and is widely used in industry for POL and VR applications. However, the capacitor voltage sideband effect, which casues the instability problem when ceramic capacitors are employed, also needs to be taken into consideration in modeling. Chapter III proposed a unified equivalent circuit model of V2 control, the model is built based on non-ideal voltage source concept. The model represents capacitor voltage sideband effect with a Re2-Le2 branch, which forms the double pole by resonating with power stage output capacitor. The equivalent circuit model is a complete model and can be used to examine all the transfer functions. Bsed on the unified equivalent circuit model, design guidelines for VR applications and general POL applications are provided in Chapter IV, for both constant on-time V2 control and constant frequency V2 control.
For resonant converters, the small-sginal modelling is very challenging as some of the state variables do not have dc components but contain strong switching frequency component and therefore the average concept breaks down. For SRC, the equivalent circuit model proposed by E. Yang in [E26] based on the results by the extended describing function concept is the most successful model. However, the order of the equivalent circuit model is too high and the transfer functions are still derived based on numerical solution instead of analytical solutions. Chapter V proposes a methodology to simplify the fifth-order equivalent circuit of SRC to a third-order equivalent circuit. The proposed equivalent circuit model can be used to explain the beat frequency dynamics: when switching frequency is far away from resonant frequency, beat frequency will occur; when the two frequencies are close, beat frequency will disappear and another double pole which is determined by equivalent inductor and output capacitor will be formed. For the first time, analytical solutions are provided for all the transfer functions which are very helpful for feedback design.
LLC resonant converters are widely adopted as front-end converter in distributed power system for the telecom, computer and network applications [F2]. Besides, LLC resonant converters are also very popular in other applications, such as LCD, LED and plasma display in TV and flat panels [F3]-[F6]; iron implanter arc power supply[F7]; solar array simulator in photovoltaic application[F8]; fuel cell applications[F9],and so on. For LLC, no simple equivalent circuit model is available and no analytical expressions of transfer functions are presented. Chapter VI proposes an equivalent circuit model for LLC resonant converter. When Fs ≥ Fo, Lm is clamped by the output voltage and LLC behaves very similar as SRC. As a result, the dynamic behavior is similar as SRC: when switching frequency is larger than resonant frequency, the beat frequency double pole show up and the circuit is third-order; when switching frequency is close to resonant frequency, beat frequency double pole disappear and a new double pole formed by equivalent inductor Le and equivalent output capacitor Cf show up. The circuit reduces to second order. When Fs
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Mumcu, Gokhan. "EM Characterization of Magnetic Photonic / Degenerate Band Edge Crystals and Related Antenna Realizations." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1221860344.
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Crampton, Raymond J. "A nonlinear statistical MESFET model using low order statistics of equivalent circuit model parameter sets." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-03032009-040420/.
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Kim, Jae Hong. "Wide-Band and Scalable Equivalent Circuit Model for Multiple Quantum Well Laser Diodes." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7129.
Full textAbstract:
This dissertation presents a wide-band lumped element equivalent circuit model and a building block-based scalable circuit model for multiple quantum well laser diodes. The wide-band multiple-resonance model expresses two important laser diode characteristics such as input reflection and electrical-to-optical transmission together. Additionally, it demonstrates good agreements with the measurement results of the selected commercial discrete laser diodes. The proposed building block-based modeling approach proves its validity using a numerically derived scalable rate equation. Since success in a circuit design depends largely on the availability of accurate device models, the practical application of the proposed models provides improved accuracy, simple implementation and a short design time.
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Pinello, William Patrick. "Electromagnetic modeling of noise interactions in packaged electronics using the partial element equivalent circuit formulation." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282565.
Full textAbstract:
The Partial Element Equivalent Circuit method is used to develop a flexible, hierarchical electromagnetic modeling and simulation environment for the analysis of noise generation and signal degradation mechanisms in packaged electronic components and systems. The circuit-oriented approach used by the method for the development of the numerical approximation of the electric field integral equation is used to develop a SPICE-compatible, yet fully dynamic, discrete approximation of the electromagnetic problem. Contrary to other full-wave formulations, the proposed method has the important attribute of lending itself to a very systematic and physical model complexity reduction on the basis of the electrical size of the various portions of the system. Thus, a hybrid electromagnetic modeling and simulation environment is established for the analysis of complex structures, which exhibit large variation in electrical size over their volume, using a combination of lumped circuit elements, transmission lines, as well as three-dimensional distributed electromagnetic models which may or may not account for retardation, depending on the electrical size of the part of the structure that is being modeled. These special attributes of the proposed electromagnetic simulation environment are demonstrated through several examples from its application to the modeling of noise interactions in generic interconnect and package geometric.
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Iftakhar, Mohammad M. "Thevenin Equivalent Circuit Estimation and Application for Power System Monitoring and Protection." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_theses/583.
Full textAbstract:
The Estimation of Thevenin Equivalent Parameters is useful for System Monitoring and Protection. We studied a method for estimating the Thevenin equivalent circuits. We then studied two applications including voltage stability and fault location. A study of the concepts of Voltage Stability is done in the initial part of this thesis. A Six Bus Power System Model was simulated using MATLAB SIMULINK®. Subsequently, the Thevenin Parameters were calculated. The results were then used for two purposes, to calculate the Maximum Power that can be delivered and for Fault Location.
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Starke, E., U. Marschner, A. B. Flatau, and J. H. Yoo. "Improved equivalent circuit modeling and simulation of magnetostrictive tuning fork gyro sensors." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A35136.
Full textAbstract:
In this paper a new equivalent circuit is presented which describes the dynamics of a prototype micro-gyro sensor. The concept takes advantage of the principles employed in vibratory gyro sensors and the ductile attributes of GalFeNOL to target high sensitivity and shock tolerance. The sensor is designed as a tuning fork structure. A GalFeNOL patch attached to the y-z surface of the drive prong causes both prongs to bending the x-z plane (about the y axis) and a patch attached to the x-z surface of the sensing prong detects Coriolis-force induced bending in the y-z plane (about the x axis). A permanent magnet is bonded on top of each prong to give bias magnetic fields. A solenoid coil surrounding the drive prong is used to produce bending in the x-z plane of both prongs. The sensing prong is surrounded by a solenoid coil with N turns in which a voltage proportional to the time rate of change of magnetic flux is induced.
The equivalent circuit enables the efficient modeling of a gyro sensor and an electromechanical behavioral simulation using the circuit simulator SPICE. The prongs are modeled as wave guiding bending beams which are coupled to the electromagnetic solenoid coil transducer. In contrast to known network approaches, the proposed equivalent circuit is the first tuning fork model, which takes full account of the fictitious force in a constant rotating frame of reference. The Coriolis force as well as the centrifugal force on a concentrated mass are considered.
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Tuo, Mingguang, Dongchao Xu, Si Li, Min Liang, Qi Zhu, Qing Hao, and Hao Xin. "Nonlinear Microwave Characterization of CVD Grown Graphene." IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2016. http://hdl.handle.net/10150/620930.
Full textAbstract:
Linear and nonlinear microwave properties of chemical vapor deposition (CVD)-grown graphene are characterized by incorporating a coplanar waveguide (CPW) transmission-line test structure. The intrinsic linear transport properties (S-parameters) of the graphene sample are measured and
extracted via a deembedding procedure and then fitted with an equivalent circuit model up to 10 GHz. A statistical uncertainty analysis based on multiple measurements is implemented to esti-
mate the error of the extracted graphene linear parameters as well. Nonlinear properties (second- and third-order harmonics as a function of fundamental input power) of the sample are also measured with a fundamental input signal of 1 GHz. Clear harmonics generated from graphene are observed, while no obvious fundamental power saturation is seen. The measured nonlinearity is applied in a graphene patch antenna case study to understand its influence on potential applications in terms of third-order intermodulation levels.
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Silveira, Luís Miguel. "Model order reduction techniques for circuit simulation." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36451.
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Lin, Ray-Lee. "Piezoelectric Transformer Characterization and Application of Electronic Ballast." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29948.
Full textAbstract:
The characterization and modeling of piezoelectric transformers are studied and developed for use in electronic ballasts. By replacing conventional L-C resonant tanks with piezoelectric transformers, inductor-less piezoelectric transformer electronic ballasts have been developed for use in fluorescent lamps.
The piezoelectric transformer is a combination of piezoelectric actuators as the primary side and piezoelectric transducers as the secondary side, both of which work in longitudinal or transverse vibration mode. These actuators and transducers are both made of piezoelectric elements, which are composed of electrode plates and piezoelectric ceramic materials. Instead of the magnetic field coupling between the primary and secondary windings in a conventional magnetic core transformer, piezoelectric transformers transfer electrical energy via electro-mechanical coupling that occurs between the primary and secondary piezoelectric elements for isolation and step-up or step-down voltage conversion. Currently, there are three major types of piezoelectric transformers: Rosen, thickness vibration mode, and radial vibration mode, all three of which are used in DC/DC converters or in electronic ballasts for fluorescent lamps. Unlike the other two transformers, the characterization and modeling of the radial vibration mode piezoelectric transformer have not been studied and developed prior to this research work.
Based on the piezoelectric and wave equations, the physics-based equivalent circuit model of radial vibration mode piezoelectric transformers is derived and verified through characterization work.
Besides the major vibration mode, piezoelectric transformers have many spurious vibration modes in other frequency ranges. An improved multi-branch equivalent circuit is proposed, which more precisely characterizes radial vibration mode piezoelectric transformers to include other spurious vibration modes in wide frequency ranges, as compared with the characterizations achieved by prior circuits.
Since the equivalent circuit of piezoelectric transformers is identical to the conventional L-C resonant tank used in electronic ballasts for fluorescent lamps, piezoelectric transformers replace the conventional L-C resonant tank in order to reduce the amount and cost of electronic components for the electronic ballasts. With the inclusion of the radial vibration mode piezoelectric transformer, the design and implementation of inductor-less piezoelectric transformer electronic ballast applications have been completed.Ph. D.
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Morua, Michael L. "A Circuit Model for an Inductive Strip in Homogeneous Finline." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238001.
Full textAbstract:
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 1990.Thesis Advisor(s): Knorr, Jeffrey B. Second Reader: Janaswamy, R. "June 1990." Description based on title screen as viewed on October 19, 2009. DTIC Indicator(s): Homogeneous finlines, Inductive strips, Theses, Program listings. Author(s) subject terms: Finline, Discontinuity, Inductive, Strip. Includes bibliographical references (p. 98). Also available online.
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Yan, Yingyi. "Unified Three-terminal Switch Model for Current Mode Controls." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/35647.
Full textAbstract:
Current-mode control architectures with different implementation approaches have been an indispensable technique in many applications, such as voltage regulator, power factor correction, battery charger and LED driver. Since the inductor current ramp, one of state variables influenced by the input voltage and the output voltage, is used in the modulator in current-mode control without any low pass filter, high order harmonics play important role in the feedback control. This is the reason for the difficulty in obtaining the small-signal model for current-mode control in the frequency domain. A continuous time domain model was recently proposed as a successful model for current-mode control architectures with different implementation. However, the model was derived by describing function method, which is very arithmatically complicated, not to mention time consuming. Although an equivalent circuit for a current mode control Buck converter was proposed to help designers to use the model without involving complicated math, the equivalent circuit is not a complete model. Moreover, no equivalent circuit for other topologies is available for designers. In this thesis, the primary objective is to develop a unified three-terminal switch model for current-mode control with different implementation methods, which are applicable in all the current mode control power converters.
First, the existing model for current mode control is reviewed. The limitation of average models and the discrete time model for current-mode control is identified. The continuous time model and its equivalent circuit of Buck converter is introduced. The deficiency of the equivalent circuit is discussed.
After that, a unified three-terminal switch model for current mode control is presented. Based on the observation, the PWM switch and the closed current loop is taken as an invariant sub-circuit which is common to different DC/DC converter topologies. A basic small signal relationship between terminal currents is studied and the result shows that the PWM switch with current feedback preserves the property of the PWM switch in power stage. A three-terminal equivalent circuit is developed to represent the small signal behavior of this common sub-circuit. The proposed model is a unified model, which is applicable in both constant frequency modulation and variable frequency modulation. The physical meaning of the three-terminal equivalent circuit model is discussed. The model is verified by SIMPLIS simulation in commonly used converters for both constant frequency modulation and variable frequency modulation.
Then, based on the proposed unified model, a comparison between different current mode control implementations is presented. In different applications, different implementations have their unique benefit on extending control bandwidth. The properties of audio susceptibility and output impedance are discussed. It is found that, for adaptive voltage positioning design, constant on-time current mode control can simplifies the outer loop design.
Next, since multiphase interleaving structure is widely used in PFC, voltage regulator and other high current applications, the model is extended to multiphase current mode control. Some design concerns are discussed based on the model.
As a conclusion, a unified three-terminal switch model for current mode controls is investigated. The proposed model is quite general and not limited by implementation methods and topologies. All the modeling results are verified through simulation and experiments.Master of Science
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Courey, Karim Joseph. "An Investigation of the Electrical Short Circuit Characteristics of Tin Whiskers." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/38.
Full textAbstract:
Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance electrical shorts may not occur at lower voltage levels. In these experiments, the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit was studied. From this data, the probability of an electrical short was estimated, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. Also, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross-sectioned and studied using a focused ion beam (FIB). The rare polycrystalline structure seen in the FIB cross section was confirmed using transmission electron microscopy (TEM). The FIB was also used to cross section two card guides to facilitate the measurement of the grain size of each card guide's tin plating to determine its finish.
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Pade, Jonas. "Analysis and waveform relaxation for a differential-algebraic electrical circuit model." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/23044.
Full textAbstract:
Die Hauptthemen dieser Arbeit sind einerseits eine tiefgehende Analyse von nichtlinearen differential-algebraischen Gleichungen (DAEs) vom Index 2, die aus der modifizierten Knotenanalyse (MNA) von elektrischen Schaltkreisen hervorgehen, und andererseits die Entwicklung von Konvergenzkriterien für Waveform Relaxationsmethoden zum Lösen gekoppelter Probleme. Ein Schwerpunkt in beiden genannten Themen ist die Beziehung zwischen der Topologie eines Schaltkreises und mathematischen Eigenschaften der zugehörigen DAE.
Der Analyse-Teil umfasst eine detaillierte Beschreibung einer Normalform für Schaltkreis DAEs vom Index 2 und Abschätzungen, die für die Sensitivität des Schaltkreises bezüglich seiner Input-Quellen folgen. Es wird gezeigt, wie diese Abschätzungen wesentlich von der topologischen Position der Input-Quellen im Schaltkreis abhängen.
Die zunehmend komplexen Schaltkreise in technologischen Geräten erfordern oftmals eine Modellierung als gekoppeltes System. Waveform relaxation (WR) empfiehlt sich zur Lösung solch gekoppelter Probleme, da sie auf die Subprobleme angepasste Lösungsmethoden und Schrittweiten ermöglicht. Es ist bekannt, dass WR zwar bei Anwendung auf gewöhnliche Differentialgleichungen konvergiert, falls diese eine Lipschitz-Bedingung erfüllen, selbiges jedoch bei DAEs nicht ohne Hinzunahme eines Kontraktivitätskriteriums sichergestellt werden kann. Wir beschreiben allgemeine Konvergenzkriterien für WR auf DAEs vom Index 2. Für den Fall von Schaltkreisen, die entweder mit anderen Schaltkreisen oder mit elektromagnetischen Feldern verkoppelt sind, leiten wir außerdem hinreichende topologische Konvergenzkriterien her, die anhand von Beispielen veranschaulicht werden. Weiterhin werden die Konvergenzraten des Jacobi WR Verfahrens und des Gauss-Seidel WR Verfahrens verglichen. Simulationen von einfachen Beispielsystemen zeigen drastische Unterschiede des WR-Konvergenzverhaltens, abhängig davon, ob die Konvergenzbedingungen erfüllt sind oder nicht.The main topics of this thesis are firstly a thorough analysis of nonlinear differential-algebraic equations (DAEs) of index 2 which arise from the modified nodal analysis (MNA) for electrical circuits and secondly the derivation of convergence criteria for waveform relaxation (WR) methods on coupled problems. In both topics, a particular focus is put on the relations between a circuit's topology and the mathematical properties of the corresponding DAE. The analysis encompasses a detailed description of a normal form for circuit DAEs of index 2 and consequences for the sensitivity of the circuit with respect to its input source terms. More precisely, we provide bounds which describe how strongly changes in the input sources of the circuit affect its behaviour. Crucial constants in these bounds are determined in terms of the topological position of the input sources in the circuit. The increasingly complex electrical circuits in technological devices often call for coupled systems modelling. Allowing for each subsystem to be solved by dedicated numerical solvers and time scales, WR is an adequate method in this setting. It is well-known that while WR converges on ordinary differential equations if a Lipschitz condition is satisfied, an additional convergence criterion is required to guarantee convergence on DAEs. We present general convergence criteria for WR on higher index DAEs. Furthermore, based on our results of the analysis part, we derive topological convergence criteria for coupled circuit/circuit problems and field/circuit problems. Examples illustrate how to practically check if the criteria are satisfied. If a sufficient convergence criterion holds, we specify at which rate of convergence the Jacobi and Gauss-Seidel WR methods converge. Simulations of simple benchmark systems illustrate the drastically different convergence behaviour of WR depending on whether or not the circuit topological convergence conditions are satisfied.
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Lim, Eugene J. (Eugene Jungsud) 1980. "An engineering model of lower thalamo-cortico-basal ganglionic circuit function." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/28458.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (leaves 59-60).
An engineering model of lower thalamo-cortico-basal ganglionic circuit functionality was extended and tested. This model attempts to explain the circuitry of the basal ganglia, examine its functional properties, and integrate these properties into an understanding of the diseases of the basal ganglia, such as Parkinson's disease and Huntington's disease. Using this model, simulations of various movements were developed, specifically those of the following: 1) one-step, cruise movements, 2) asynchronous, cruise movements, and 3) sequential cruise movements. Results of these movements include simulated movements of both normal patients and patients with movement disorders.
by Eugene J. Lim.
M.Eng.
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Busuioc, Dan. "Circuit Model Parameter Extraction and Optimization for Microwave Filters." Thesis, University of Waterloo, 2002. http://hdl.handle.net/10012/804.
Full textAbstract:
This thesis presents a method for parameter extraction of circuit elements from microwave filters. This diagnosis method can be applied to a sufficiently large number of filters and it can also be used in conjunction with a neural network model for filter design, greatly reducing development time. This thesis is an introduction of parameter extraction and circuit modelling through use of neural networks. It also presents an implementation of the proposed method as well as numerical results and validation data. Detailed implementation code is presented in the appendix.
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Bagheri, Rajeoni Alireza. "ANALOG CIRCUIT SIZING USING MACHINE LEARNING BASED TRANSISTORCIRCUIT MODEL." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1609428170125214.
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Suwanasri, Thanapong. "Investigation on no load mechanical endurance and electrical degradation of a circuit breaker model under short circuit current interruption." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979106028.
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Pade, Jonas [Verfasser]. "Analysis and waveform relaxation for a differential-algebraic electrical circuit model / Jonas Pade." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1237685346/34.
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Hsieh, Yi-Hsun. "Accurate Small-Signal Modeling for Resonant Converters." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100941.
Full textAbstract:
In comparison with PWM converters, resonant converters are gaining increasing popularity for cases in which efficiency and power density are at a premium. However, the lack of an accurate small-signal model has become an impediment to performance optimization. Many modeling attempts have been made to date. Besides the discrete time-domain modeling, most continuous-time modeling approaches are based on fundamental approximation, and are thus unable to provide sufficient accuracy for practical use. An equivalent circuit model was proposed by Yang, which works well for series resonant converters (SRCs) with high Q (quality factor), but which is inadequate for LLC resonant converters. Furthermore, the model is rather complicated, with system orders that are as high as five and seven for the SRC and LLC converter, respectively.
The crux of the modeling difficulty is due to the underlying assumption based on the use of a band-pass filter for the resonant tank in conjunction with a low-pass output filter, which is not the case for most practical applications. The matter is further complicated by the presence of a rectifier, which is a nonlinearity that mixes and matches the original modulation frequency. Thus, the modulation signal becomes intractable when using a frequency-domain modeling approach.
This dissertation proposes an extended describing function modeling that is based on a Fourier analysis on the continuous-time-domain waveforms. Therefore, all important contributions from harmonics are taken into account. This modeling approach is demonstrated on the frequency-controlled SRC and LLC converters. The modeling is further extended to, with great accuracy, a charge-controlled LLC converter.
In the case of frequency control, a simple third-order equivalent circuit model is provided with high accuracy up to half of the switching frequency. The simplified low-frequency model consists of a double pole and a pair of right-half-plane (RHP) zeros. The double pole, when operated at a high switching frequency, manifests the property of a well-known beat frequency between the switching frequency and the resonant frequency. As the switching frequency approaches the resonant frequency of the tank, a new pair of poles is formed, representing the interaction of the resonant tank and the output filter. The pair of RHP zeros, which contributes to additional phase delay, was not recognized in earlier modeling attempts.
In the case of charge control, a simple second-order equivalent circuit model is provided. With capacitor voltage feedback, the order of the system is reduced. Consequently, the resonant tank behaves as an equivalent current source and the tank property is characterized by a single pole. The other low-frequency pole represents the output capacitor and the load. However, the capacitor voltage feedback cannot eliminate the high-frequency poles and the RHP zeros.
These RHP zeros may be an impediment for high-bandwidth design if not properly treated. Based on the proposed model, these unwanted RHP zeros can be mitigated by either changing the resonant tank design or by proper feedback compensation. The accurate model is essential for a high-performance high-bandwidth LLC converter.Doctor of Philosophy
For high-frequency power conversion, resonant converters are increasingly popular. However, the lack of an accurate small-signal model has become an impediment to performance optimization. The existing equivalent circuit model and its simplified circuit were based on fundamental approximation, where the resonant tank was deemed a good band-pass filter. These models work well for series resonant converters (SRCs) with high Q (quality factor), but are inadequate for LLC resonant converters. The crux of the modeling difficulty is due to the fact that the operation of this type of resonant converter is based on the use of a band-pass filter in conjunction with a low-pass filter. The matter is further complicated by the presence of a rectifier, which is a nonlinearity that mixes and matches the original modulation frequency. Thus, the modulation signal becomes intractable when using a frequency-domain modeling approach. This dissertation proposes an extended describing function modeling that is based on a Fourier analysis on the continuous-time-domain waveforms. Therefore, all important contributions from harmonics are taken into account. This modeling approach is demonstrated on the frequency-controlled SRC, frequency-controlled LLC converter, and charge-controlled LLC converter, and the resulting models are proven to be accurate at all frequencies. A simple equivalent circuit model is provided that targets the frequency range below the switching frequency. This simple, accurate model is able to predict the small-signal behaviors of the LLC converter with high accuracy at half of the switching frequency. At high modulation frequencies, the resonant converter behaves like a non-minimum phase system, which was neither recognized nor characterized before. This property can be represented by RHP zeros, and these RHP zeros may be an impediment for high-bandwidth design if not properly treated. Based on the proposed model, these unwanted RHP zeros can be mitigated by either changing the resonant tank design or by proper feedback compensation. Accurate modeling is essential for a high-performance high-bandwidth LLC converter.
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Wu, Meng-Chun, and 吳孟駿. "Frequency-Modulated Electrical Properties of InAs Quantum Dots Schottky Diode : Using Equivalent RC Circuit Model." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/uqd699.
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碩士國立交通大學
電子物理系所
105
There are two cases in this study. In the first case, we discuss frequency-modulated electrical properties of InAs/InGaAs dot-in-well layer embedded in a GaAs Schottky diode, and build the equivalent RC circuit model to explain this appearance. After we check the equivalent RC circuit model, we express the capacitance and conductance to frequency, and work out the capacitance of Schottky and QD, and finally simulate the C-f and G/f-f plots. In the second case, we discuss the capacitance of Schottky, capacitance of QD and resistance of QD in the different bias, and use the theoretical arithmetic to calculate the capacitance and barrier height of QD under zero bias. Then we compare the results of theoretical arithmetic with equivalent RC circuit model. To sum up, we use frequency-modulated electrical measurement for QD layer, which is located outside the depletion region, and then demonstrate the capacitance and resistance of QD with equivalent RC circuit model and theoretical arithmetic. As a result, we confirm the equivalent RC circuit model is correct.
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Traub, Felix Maximilian. "Automated Construction of Equivalent Electrical Circuit Models for Electromagnetic Components and Systems." Phd thesis, 2014. https://tuprints.ulb.tu-darmstadt.de/3805/1/Dissertation_Traub.pdf.
Full textAbstract:
The description of electromagnetic components and systems by electrical circuit models is indispensable for a wide range of applications: In the field of EMC, electrical circuit models are ideally suited for the detection of EMC coupling paths, which are very difficult to track for 3D geometries. In the field of numerical optimization techniques, electrical circuit models offer short simulation times and allow the coupling of the electromagnetic domain to other physical domains. In the field of power electronics, electrical circuit models describe energy dissipation due to parasitic electromagnetic interactions.
The construction of an equivalent electrical circuit model is in general cumbersome and less formalized than a description in terms of electromagnetic fields. No general and reliable technique for the automated construction of equivalent electrical circuit models exists. The aim of this thesis is the development of a technique that allows a fully automated construction of equivalent electrical circuit models from 3D geometry information. Instead of constructing the circuit directly from geometry data, our approach consists of reducing a field-theoretical model to an equivalent electrical circuit model. In this way, we exploit the generality of the field-theoretical approach, which can be applied for a wide range of geometries using state-of-the-art simulation techniques. The electromagnetic effects having the largest impact in the frequency range of interest are then used for the construction of the electrical circuit model. The circuit elements can be seen as condensed representations of these field-theoretical processes. The reduction process allows a very direct assessment of the accuracy of the electrical circuit model.
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Pan, Sheng-Shiang, and 潘盛祥. "The Electrical Properties of Schottky Diode Modulated by Electrons Confined in InAs Quantum Dots：Using Equivalent RC Circuit Model." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/34855814166111760222.
Full textAbstract:
碩士國立交通大學
電子物理系所
102
In the study, the InAs/InGaAs quantum dots (QDs) growth under low temperature produces the EL2 defect. We discuss excess electrons accumulated in quantum dots (QDs) generate the potential drop, and the ability of electron confinement is enhanced by EL2 defect. Initially, the optical properties are studied by photoluminescence (PL), and the information of defect is found by deep level transient spectroscopy (DLTS). We observe the QDs with EL2 defect, the Capacitance-Voltage (C-V) performance were influenced obviously under illumination. Therefore, we assume the sample is the GaAs Schottky diode series connect with the QDs of capacitor property. We establish the equivalent RC circuit model, using the RS parallel connect with the Cs represent the GaAs Schottky diode, and the CQD represent the QDs. Under sweeping bias, we inference the Current-Voltage (I-V) relationship, that current and sweep rate are in direct proportion. Furthermore, we correct the Possion’s equation when the GaAs Schottky series connect with a capacitor. The capacitance is dependent on the RC time constant due to the applied bias contribute different ratio to two devices. The InAs QDs with EL2 defect sample were studied by C-V and I-V measurement under illumination, then the result is similar to the assumption of RC equivalent circuit. The response of capacitance and current are dependent on EL2 defect and light energy. Finally, we discuss the band bending around the QDs, and the EL2 defect induce the QDs with the property of capacitor.
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(7456577), Xiang Zhang. "A COUPLED THERMAL/ELECTRIC CIRCUIT MODEL FOR DESIGN OF MVDC CABLES." Thesis, 2019.
Find full textAbstract:
Cables play an important role in the design of a power system. DC cable design presents unique challenges due to the fact that space charge can accumulate within the dielectric over time. Space charge accumulation is a function of temperature, electric field, and dielectric properties. Of particular concern is that the space charge leads to electric fields that are sufficient to break down the cable, particularly during transient conditions such as voltage reversal.
In this research, a focus is on the development of a coupled thermal- and electricalequivalent-circuit model that is general and provides the ability to predict the electric fields and space charge accumulation within single and multi-conductor DC cables. In contrast to traditional analytical models, the approach is more general, allowing for exploration of a wide spectrum of geometries. In contrast to traditional numerical methods, including finite element or finite difference, apriori knowledge of the electric field behavior is used to discretize the dielectric into a small number of electric flux tubes. The electric field dynamics within each tube are then modeled using a first order nonlinear differential equation. The relatively coarse discretization enables the solution to be computed rapidly. This is useful in population-based design where a large number of candidate evaluations is necessary to explore a design space. The modeling approach has been validated using several examples presented in the literature. In addition, its usefulness has been highlighted in the optimization of a 20 kV cable wherein objectives include minimization of mass and loss.
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(10653539), Timothy J. Donnelly. "THEVENIN EQUIVALENT CIRCUITS FOR MODELING COMMON-MODE BEHAVIOR IN POWER ELECTRONIC SYSTEMS." Thesis, 2021.
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The high-frequency switching of transistors in power electronic (PE) converters is known to cause unintended common-mode (CM) current that flows through parasitically-coupled ground paths. One way to model these currents is to utilize time-domain simulations that capture switching dynamics and the corresponding parasitic response. Although potentially useful, the small time steps required can create a computational burden and limit the usefulness of the approach. In addition, access to internal hardware needed to characterize parasitic parameters is often limited.
In this thesis, frequency-domain Thevenin equivalent circuits (TECs) are derived to model the CM behavior of PE converters. To do so, periodic linear time-varying (PLTV) analysis is used to develop Thevenin-like models that account for switching behavior of PE circuits. Subsequently, it is shown that in many applications these PLTV TECs can be reduced to traditional linear time-invariant (LTI) forms. Methods to experimentally characterize LTI TEC parameters and couple multiple TECs together for system-level analysis are then established. Finally, the TEC approach is extended to model converters in which common- and differential-mode (CM/DM) behavior are strongly coupled. Simulation and experimental results are used to validate the proposed TEC techniques.
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Wang, Yang. "A monolithic hybrid direct methanol fuel cell & an equivalent nonlinear electric circuit model for direct methanol fuel cell." 2007. http://etd.lib.fsu.edu/theses/available/etd-11092007-234009.
Full textAbstract:
Thesis (Ph. D.)--Florida State University, 2007.Advisor: Jim P. Zheng, Florida State University, FAMU-FSU College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed March 14, 2008). Document formatted into pages; contains viii, 87 pages. Includes bibliographical references.
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Ragavan, K. "An Efficient Solution To Generalized Model Of A Transformer Winding And Localization Of Discrete Changes Based On Measurements." Thesis, 2006. http://hdl.handle.net/2005/354.
Full textAbstract:
High voltage power transformers are designed to withstand a variety of overvoltages and short circuit forces. Occurrence of these events in a power system is natural, inevitable, and one of the main causes of transformer failure. Therefore, an early and reliable detection of an incipient fault is paramount. To this end, diagnostic testing and condition monitoring, not only enables power utilities in early detection of incipient fault-like conditions, but also is a practical way of optimizing existing assets, lowering operating costs, scheduling maintenance, preventing unplanned outages, etc. and consequently improve efficiency.
Over the years, many monitoring and diagnostic methods have evolved. In par-
ticular, low voltage impulse and frequency response analysis or transfer function
approaches have emerged as useful tools in detecting winding deformations. Literature study reveals that although much has been acclaimed about these methods, advancement in interpretation of acquired data must be rigorously pursued, to facilitate a more meaningful assessment. As a matter of fact, diagnosis (which means interpretation of monitored data) has at-the-most been confined to a mere comparison of two subsequently acquired data sets. This philosophy certainly needs to be improved, to realize the true potential of monitoring/diagnostic tools. Achieving this goal calls for newer impetus. It is natural that there will arise many problems while achieving this goal and they will have to be resolved. Keeping these aspects in mind, the objective of this thesis was aimed at developing Solutions to two specific topics that are closely related to and concern the
transformer winding, namely,
* An efficient solution to the generalized model of a transformer winding, with no particular limitation on the size of network and number of windings, no restriction on circuit topology and terminal condition, etc.
* Propose a method to locate the position, quantum and type of change (i.e. deformation) a model winding undergoes, based on terminal measurements.
Details of these approaches are presented in this thesis, which is divided into two parts.
1. A comprehensive analysis of the behaviour of a transformer winding under impulse excitation and its interaction with adjacent windings was until now severely limited, due to the simplifying assumptions imposed (by the existing approaches), like neglecting interaction with neighbouring windings, Ignoring loss, considering only a few sections, etc. thereby rendering the computed results less accurate. A solution considering all these aspects often times results in a very large-sized circuit that needs to be solved. Although circuit simulation software afford iterative solutions, a direct estimation of poles and zeros of any desired network function is not possible.
In the first part of the thesis, a novel and closed-form (i.e. analytical) solution based on state space analysis is proposed. It is shown, how the renders the entire computation to be purely numeric. Thus, time-consuming symbolic manipulations are avoided. With this feature, there is practically no limit on the size of network and no restriction on circuit topologies that can be considered. So, virtually any number of windings of a transformer can be considered, permitting a comprehensive analysis of winding behaviour and its interactions. Further, the formulation also permits computation of poles and zeros of any desired network function (e.g. transfer admittance), response to any excitation (e.g. neutral current, transferred surge), estimation of voltage distribution, etc. with
little extra effort. Hence, it would be apppropriate to term the proposed method as a \Generalized" solution. For the sole purpose of demonstration, a large-sized network (representing a two-winding transformer with 250 sections/winding) was solved and required only 700 seconds. This shows the time-efficiency achieved, and also that it is free from issues like numerical
instability, convergence problems, etc. encountered in some of the existing methods.
2. Detection of mechanical deformation in transformer windings can be achieved with a fair degree of sensitivity using frequency response methods. However, a major challenge that has remained elusive is ascertaining the \extent of damage" and likewise \its location along the winding". It is needless to say that finding these answers is crucial. Ideally, a diagnosis tool is expected to be endowed with powers to answer these questions. Therefore, it is desirable
to explore alternative ways of harnessing these embedded features, if any. This was the next motivation. Obviously, a direct solution to this problem on an actual transformer winding is far too complex. Hence, in this preliminary effort a solution was attempted considering a model winding.
However, care was taken to incorporate other winding-related nuances as far as practicable. The method was formulated based on quantities measured at the terminals.
In the second part of the thesis, a novel algorithm is proposed for determining the location, extent and type of changes intrroduced in a model winding, based on terminal measurements. It employs the well-known properties of driving-point functions and adopts an iterative circuit synthesis approach. From knowledge of the measured short-circuit and open-circuit natural frequencies, and some relevant winding design data, an equivalent circuit was synthesized (called reference circuit). Next, changes were introduced at different locations in the model winding and natural frequencies measured again. Corresponding to every new set of measured natural frequencies, a fresh circuit was synthesized (with topology remaining unchanged). A comparison of these circuits with the reference circuit revealed that a mapping could be established between changes introduced in the model winding and those predicted by the synthesized circuits. Initially, the underlying principle is discussed, and thereafter, the experimental results are presented for both continuous-disc and interleaved winding representations. The case studies involved examples wherein changes in the model winding were made to elements connected to a single tap, two physically different tap positions, multiple changes to different elements, and so on. In all cases, the positions of all the `changes' were reasonably well locatable, and so was the `type of change'. The results were very encouraging. In summary, localization of changes based on terminal measurements, is shown to be a possibility. Lastly, it is conjectured that these findings could be of some assistance in addressing the ultimate task of locating mechanical deformations in actual transformer windings.
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(9755702), Tyler James Shelly. "PARAMETRIC ANALYSIS AND OPTIMIZATION OF LONG-RANGE BATTERY ELECTRIC VEHICLE THERMAL MANAGEMENT SYSTEMS." Thesis, 2020.
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Due to increasing regulation on emissions and shifting consumer preferences, the wide adoption of battery electric vehicles (BEV) hinges on research and development of technologies that can extend system range. This can be accomplished either by increasing the battery size or via more efficient operation of the electrical and thermal systems. This thesis endeavours to accomplish the latter through comparative investigation of BEV integrated thermal management system (ITMS) performance across a range of ambient conditions (-20 °C to 40 °C), cabin setpoints (18 °C to 24 °C), and six different ITMS architectures. A dynamic ITMS modelling framework for a long-range electric vehicle is established with comprehensive sub models for the operation of the drive train, power electronics, battery, vapor compression cycle components, and cabin conditioning. This modelling framework is used to construct a baseline thermal management system, as well as for adaptation to four common systems. Additionally, a novel low-temperature waste heat recovery (LT WHR) system is proposed and shown to have potential benefits at low ambient temperatures through the reduction of the necessary cabin ventilation loading. While this system shows performance improvements, the regular WHR system offers the greatest benefit for long-range BEV drive cycles in terms of system range and transient response. With an optimal thermal management system found for long range BEV’s this system is then used as a boundary condition for a study on cooling of the battery. Battery conditioning, health, and as a result their along cell and system lifetime remains an additional concern of consumers as well as thermal systems engineers seeking to ensure safety and ensure longevity of EV battery cells. Three typical coolant flow orientations are studied to compare them under different flow conditions and thermal interface material performance. The battery cooling model is then coupled to the previously established dynamic modelling environment to demonstrate the added modelling capability (and necessity) for incorporating module-level cooling performance in both battery cooling studies and transient ITMS environments.