Thèses : « Power transformers design »

1

Carvajal, Angel J. « First principles design of coreless power transformers ». Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120875.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 117-118).
This thesis presents a theoretical foundation and methodology for designing novel 4-coil high frequency coreless power transformers from first principles via lumped equivalent circuit models. The procedure is applied to construct a design for 100W transformer with an S21 parameter value of .96. Using MATLAB and LTspice, simulation tools have been developed to produce accurate predictions of inductance, resistance, coupling coefficients, and S21 parameter values for an ensemble of coil models. These theoretical calculations have been employed for spiral and cylindrical coils and have been validated with numerous constructed experimental designs. The utility uses a first principles approach and derives these calculations directly from the physical parameters and relative positions of the coils. Simulation outputs greatly aid the engineering task of designing an efficient coreless power transformer.
by Angel J. Carvajal.
M. Eng.

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2

Shen, Wei. « Design of High-density Transformers for High-frequency High-power Converters ». Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28280.

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Moore's Law has been used to describe and predict the blossom of IC industries, so increasing the data density is clearly the ultimate goal of all technological development. If the power density of power electronics converters can be analogized to the data density of IC's, then power density is a critical indicator and inherent driving force to the development of power electronics. Increasing the power density while reducing or keeping the cost would allow power electronics to be used in more applications. One of the design challenges of the high-density power converter design is to have high-density magnetic components which are usually the most bulky parts in a converter. Increasing the switching frequency to shrink the passive component size is the biggest contribution towards increasing power density. However, two factors, losses and parasitics, loom and compromise the effect. Losses of high-frequency magnetic components are complicated due to the eddy current effect in magnetic cores and copper windings. Parasitics of magnetic components, including leakage inductances and winding capacitances, can significantly change converter behavior. Therefore, modeling loss and parasitic mechanism and control them for certain design are major challenges and need to be explored extensively. In this dissertation, the abovementioned issues of high-frequency transformers are explored, particularly in regards to high-power converter applications. Loss calculations accommodating resonant operating waveform and Litz wire windings are explored. Leakage inductance modeling for large-number-of-stand Litz wire windings is proposed. The optimal design procedure based on the models is developed.
Ph. D.

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3

Makowski, Nathanael Jared. « Proposal and Analysis of Demagnetization Methods of High Voltage Power System Transformers and Design of an Instrument to Automate the Demagnetization Process ». PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/431.

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Present demagnetization methods for large power system transformers are time consuming and can be dangerous to persons performing demagnetization. The work of this thesis was to develop improved demagnetization methods and to construct an automated instrument that would implement the methods developed. One previously developed method was analyzed for effectiveness. Then, two new methods for demagnetization were developed and also analyzed for effectiveness. An automated test instrument prototype was redesigned to be able to accommodate these methods and to improve the safety of the user. The previously developed method attempts demagnetization based on current flow behavior characteristics. The first new method is a magnetic flux estimation based on saturation time. The second new method is also based on measuring saturation time, modified to account for the variable voltage loss due to wire resistance. The second of the two new methods developed proved to be the most effective for demagnetization and was able to demagnetize a transformer within an error margin of 2%. The instrument designed to perform the demagnetization with this new routine is now in early production stages for an expanded field trial with transformer maintenance teams.

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4

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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5

Economides, Sophia Betty. « Design and application of multilayer monolithic microwave integrated circuit transformers ». Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312971.

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6

Dai, Ning. « Modeling, analysis, and design of high-frequency high-density low-profile power transformers ». Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151512/.

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7

Wilson, Colin Richard. « The design and development of fast pulsed power supplies using Transmission Line Transformers ». Thesis, University of St Andrews, 1992. http://hdl.handle.net/10023/13600.

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This thesis is concerned with the development of Transmission Line Transfomer (TLT) pulsed power supplies and the generation of fast risetime (>50ns), good quality, high repetition-rate voltage pulses for flash x-ray preionisors and other applications. It explains the principle of the TLT and reports on two TLT pulsed power supplies that have been built. The first, or prototype, produced output voltage pulses with risetimes of 50ns and durations of 200ns and was used to power a flash x-ray preionisation source for a mercury bromide laser. The second, a 50kV, 100? device, was built as part of a wider research program concerned with the development of space based pulsed power supplies. The development of ceramic tile technology is also described and the relevant electrical, mechanical and thermal properties of some barium titanate tiles given; it is then shown how ceramic tiles can be used to construct compact pulse generators for TLT systems. Finally, the subject of nonlinear dielectric pulse sharpening is introduced and pulse sharpening in a delay line ladder network containing air-core inductors and non-linear capacitors is demonstrated. It is then explained how these lines can be used to improve the output risetime of a TLT.

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8

Goad, Stephen D. « The theory and design of switched-mode power transformers for minimum conductor loss ». Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/52290.

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A comprehensive and general analysis of the electromagnetic fields, power dissipation, and energy storage within transformer windings is presented. Emphasis is placed on applications in switched-mode power conversion. One-dimensional radial variation of the field quantities is assumed. The first phase of the investigation is for sinusoidal excitation; solutions for the current density and magnetic field intensity are derived and studied in order to develop a fundamental understanding of the basic phenomena. Expressions for the power dissipation and energy storage in both single- and multi-layer windings are then derived which, upon investigation, yield a technique for minimizing the power dissipation by choosing an optimum conductor thickness. Several levels of accuracy, ranging from exact solutions to very simple and physically meaningful series approximations, are defined and examined to determine their usefulness and range of validity. The time-harmonic treatment is generalized to arbitrary periodic exoitation by means of Fourier analysis, resulting in a powerful extension of its applicability to any possible converter topology. Results for several representative waveshapes are presented from which a fundamental dependence cn the waveform bandwidth is discovered. Practical application of the theoretical analysis is considered by developing models for several couon winding types: single and multi-filar round wire, litz wire, and sheet conductors. Experimental results are presented and compared with the theoretical results for each of these cases. Finally, a design procedure is outlined for switched—mode pour transformers which is based on this work.
Ph. D.

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9

Gradzki, Pawel Miroslaw. « Core loss characterization and design optimization of high-frequency power ferrite devices in power electronics applications ». Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-165934/.

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10

Di, Capua Giulia. « Models and methods for the design of isolated power converters in high-frequency high-efficiency applications ». Doctoral thesis, Universita degli studi di Salerno, 2013. http://hdl.handle.net/10556/893.

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2011 - 2012
Isolated power supplies design requires the achievement of overall stress, losses, cost, size and reliability trade-off. This problem is of considerable importance in modern applications of power converters, as for energy saving issues as for the achievement of high power density capabilities needed to integrate the power supply into the same boards where the system they feed is hosted. The aim of this PhD dissertation is to discuss the fundamental issues regarding the design of high-efficiency high-power-density isolated power converters, related to the transformers design and to the system-level analysis of functional and parametric correlations existing among transformers and silicon devices in the achievement of high efficiency. Transformer design is the central issue in isolated switching power supplies design. Affording a preliminary reliable investigation of possible feasible power supply designs using off-the-shelf transformers can be of great help in reducing the time to prototyping and the time-to-market. Even though many off-the-shelf transformers are available today for standard applications, many special situations occur such that the design of a custom transformer is required. New design method are needed in order to enable a wider detection and investigation of possible transformer design solutions by means of a straightforward matching between the available magnetic cores, the operating conditions of the transformer to be designed and the design constraints to be fulfilled. A critical re-examination of transformers design methods discussed in technical literature has been afforded to highlighting some common misleading assumptions which can hinder the minimization of the transformer. Thus, a new design approach has been investigated and discussed, which helps in easily identifying possible transformer solutions in critical custom designs for a given application, complying with losses and size constraints. The new method is aimed at quickly identifying possible combinations of magnetic cores and windings turns number when many possible design might be feasible and a fast comparative evaluation is needed for preliminary cores selection. Novel geometric form factors of magnetic core (Kf and Kc) have been introduced and a consequent classification procedure for magnetic cores has been obtained, showing the correlation between the characteristics of the core and the specific applications in which each type of core offers major advantages in terms of minimizing losses and/or size. A magneto-electro-thermal macro model of the transformer has been adopted in order to investigate the dependency of total transformer losses on the temperature and to analyze the temperature sensitivity of form factor constraints of magnetic cores for power loss compliance. In particular, temperature-dependent boundaries curves both for the core window area and cross-section and for the form factors Kf and Kc have been obtained, allowing quick identification of feasible design solutions, complying with all design constraints, included thermal issues. Transformers and silicon devices do inextricably share the responsibility of major losses in isolated power supplies, and the optimization of the former normally impinges the one of the latter. As a consequence, the intimate correlation among these parts need to be jointly considered regarding the way the characteristics of one device influence the losses of the other one. In order to achieve reliable comparative evaluations among different design set-up, a new versatile numerical model for commutations analysis of power MOSFETs has been developed. The model takes into account the non-linear behavior of the inter-electrode capacitances and has been conceived to work as with parameters and information contained in the devices datasheets as with more detailed models. A Modified Forward Euler (MFE) numerical technique has been specifically developed and adopted in the realization of a numerical algorithm which solves the non linear system of differential equations describing the effect of parasitic capacitances in whatever operating conditions, in order to overcome the limitation exhibited by ODEs techniques for stiff problems in this particular application. The new MFE technique allows to compare the switching characteristics of MOSFETs with a good level of reliability and to obtain a detailed analysis of capacitive currents paths circulating between MOSFETs in half-bridge configuration during commutations. The numerical device-level model of the MOSFETs couples has been first tested in the analysis of basic non isolated synchronous rectification buck converter and then used into an integrated model allowing the analysis of Active Clamp Forward converters. It has been also demonstrated that the model adopted for the switching cell can be implemented in circuit simulators like Micro-Cap. The correlations existing between the parasitic parameters which characterize both transformer and MOSFETs and their impact on the switching behavior and the efficiency of such a conversion system can be effectively investigated by using such modeling approach, thus overcoming the limitations and unreliability of simplified analytical formulas for the prediction of the ZVS achievement. In particular, the integrated system model has been successfully used to determine the mutual constraint conditions between magnetic devices and solid state devices to achieve soft-switching, and their effects on the physical feasibility and design/selection of such power devices in order to achieve high efficiency. Experimental activities have been done to validate the methods and models proposed, through the implementation of on-line losses measurements techniques for both magnetic and solid state devices. The high switching frequency, high slew rates, high current and low leakage devices make such measures extremely sensitive to the parasitic circuit layout parameters. In order to achieve reliable measurements, non-conventional measurement techniques have been investigated based on the use of current sensing MOSFETs, and applied in the development and implementation of new measuring circuits. [edited by author]
XI n.s.

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11

Habibi, Saeid. « Wireless charging of electric vehicles based on resonant inductive power transformers ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.

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Abstract Electric vehicles and their charging stations are among important applications in today's world. The E-mobility industry is changing day-to-day with new ways to reduce charging time of electric vehicles, ease of use in charging process, increasing the efficiency and sometimes remote control access of the charging system. To accomplish this, resonant inductive power transfers is one of the method that can be hired to transfer power to electric vehicles (EVs) over an air-gap and can remarkably improve the range, safety and convenience of the EV battery charging. However, implementation of a large scale wireless charging infrastructure of electric vehicles (e.g. for taxi fleet in a city) is still one of the major difficulties of such technology. Issues related to determining the physical sizes of the coil pads, standardization, technical interoperability, safety and designing the appropriate wireless charging system to be used for different EVs are among those difficulties. The important target of doing this study is to understand the feasibility of installation of wireless charging stations for electric vehicle in terms of technical and financial issues, and understanding that which size of chargers are needed to install for electric vehicles. Electrical synchronization and interoperability of primary and secondary coils are other issues investigated. In the following chapters, financial and economic analysis of implementation of the wireless charging infrastructure for the taxi and van fleet in an urban area are discussed. It can be concluded that implementation of wireless charging infrastructure for electric vehicles in urban areas for taxi fleet and delivery van drivers could bring many advantages because of specific working routine and stop time that they have during each working day. Increment of anxiety range, and reduction of charging time, convenience, being needless of tedious conventional charging cables, saving money are major advantages.

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Larsson, Jenny, et David Håkansson. « Evaluation of software using the finite element method by simulating transformers and inductors ». Thesis, Linköpings universitet, Elektroniksystem, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-65759.

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In this bachelor thesis several software, capable of calculating andsimulating complex problems concerning the power losses in inductors andtransformers with the finite element method, have been evaluated and used tosolve test cases provided by the commissioner. The software have been evaluatedwith respect to several requirements stated by the commissioner.The aim is to be able to simulate power losses and inductance levels in complexdesigns of inductors and transformers. By reading the manuals to the software, aview of the methods and equations the different software use for their calculationshave been established. The enclosed tutorials have provided the knowledge forthe operations of the different software. By designing the test models providedby the commissioner, a deeper understanding of the work area has been reached.The test results provides an answer for the test models, the behaviour of themagnetic field has been analysed for the models and the calculated power lossesseem to correspond to the behaviour of the prototypes.The evaluation of the software has been done with regard to the commissionersrequirements. The recommendation will be to use either FEMM 4.2 or QuickField5.7, both software have a short training curve and an interface easy to maintain.For problems requiring a transient analysis the recommendation is QuickField, butthe material library maintainability is better in FEMM 4.2. Regarding COMSOLMultiphysics 3.5 and Ansys RAnsoft Maxwell Student Version 9, both softwareare highly qualified for the complex calculations needed for these kind of problems.The training curve for these software is however much longer than for the othertwo software and for the commissioner to be able to fully use all the possibilitiesin the software this will not be efficient.

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13

Rhodes, Scott A. (Scott Adrian). « The effects of separable cores on high power transformer design ». Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41419.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
Includes bibliographical references (p. 157-159).
by Scott A. Rhodes.
M.Eng.

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14

Aripirala, Manoj Kumar. « A compact switching mode class-f power amplifier design ». Thesis, Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/55062.

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Even though there had been extensive research in Switching Mode Power Amplifier design their applications at industry level are quite limited. This is because a Fully-Integrated Switching Mode Power Amplifier using conventional active devices such as Bipolar Junction Transistors (BJT) or Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is challenging due to the inherent design challenges in the Switching Power Amplifier design. A Fully-Integrated Differential Class-F2,3 Power Amplifier design is explored for this Thesis research. This Power Amplifier has a maximum theoretical efficiency of 90.7% but this value is reduced because of the switching nature of the active device, parasitic effects associated with layout and the quality factor of the passive components used. Waveform shaping required for a Class-F Power Amplifier is done using the stray inductances within a non-ideal transformer instead of individual inductors. This techniques effective reduces the foot prints of two inductors for the tuning network design and make a Fully-Integrated solution more practical.

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15

Chan, Yick-po, et 陳奕寶. « Advanced transformer construction techniques for electromagnetic interference reduction in switch mode power supplies ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47027484.

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16

Ahmed, Mohamed Hassan Abouelella. « Power Architectures and Design for Next Generation Microprocessors ». Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/103175.

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With the rapid increase of cloud computing and the high demand for digital content, it is estimated that the power consumption of the IT industry will reach 10 % of the total electric power in the USA by 2020. Multi-core processors (CPUs) and graphics processing units (GPUs) are the key elements in fulfilling all of the digital content requirements, but come with a price of more power-hungry processors, driving the power per server rack to 20 KW levels. The need for more efficient power management solutions on the architecture level, down to the converter level, is inevitable. Recently, data centers have replaced the 12V DC server rack distribution with a 48V DC distribution, producing a significant overall system efficiency improvement. However, 48V rack architecture raises significant challenges for the voltage regulator modules (VRMs) required for powering the processor. The 48V VRM in the vicinity of the CPU needs to be designed with very high efficiency, high power density, high light-load efficiency, as well as meet all transient requirements by the CPU and GPU. Transferring the well-developed multi-phase buck converter used in the 12V VRM to the 48V distribution platform is not that simple. The buck converter operating with 48V, stepping down to sub 2V, will be subjected to significant switching related loss, resulting in lower overall system efficiency. These challenges drive the need to look for more efficient architectures for 48V VRM solutions. Two-stage conversions can help solve the design challenges for 48V VRMs. A first-stage unregulated converter is used to step-down the 48V to a specific intermediate bus voltage. This voltage will feed a multi-phase buck converter that powers the CPU. An unregulated LLC converter is used for the first-stage converter, with zero voltage switching (ZVS) operation for the primary side switches, and zero current switching (ZCS) along with ZVS operation, for the secondary side synchronous rectifiers (SRs). The LLC converter can operate at high frequency, in order to reduce the magnetic components size, while achieving high-efficiency. The high-efficiency first-stage, along with the scalability and high bandwidth control of the second-stage, allows this architecture to achieve high-efficiency and power density. This architecture is simpler to adopt by industry, by plugging the unregulated converter before the existing multi-phase buck converters on today's platforms. The first challenge for this architecture is the transformer design of the first-stage LLC converter. It must avoid all of the loss associated with high frequency operations, and still achieve high power density without scarifying efficiency. In this thesis, the integrated matrix transformer structure is optimized by SR integration with windings, interleaved primary side termination, and a better PCB winding arrangement to achieve high-efficiency and power density, and minimize the losses associated with high-frequency operations. The second challenge is the light load efficiency improvement. In this thesis a light load efficiency improvement is proposed by a dynamic change of the intermediate bus voltage, resulting in more than 8 % light load efficiency improvements. The third challenge is the selection of the optimal bus voltage for the two-stage architecture. The impact of different bus voltages was analyzed in order to maximize the overall conversion efficiency. Multiple 48V unregulated converters were designed with maximum efficiency >98 %, and power densities >1000 W/in3, with different output voltages, to select the optimal bus voltage for the two-stage VRM. Although the two-stage VRM is more scalable and simpler to design and adopt by current industry, the efficiency will reduce as full power flows in two cascaded DC/DC converters. Single-stage conversion can achieve higher-efficiency and power-density. In this thesis, a quasi-parallel Sigma converter is proposed for the 48V VRM application. In this structure, the power is shared between two converters, resulting in higher conversion efficiency. With the aid of an optimized integrated magnetic design, a Sigma converter suitable for narrow voltage range applications was designed with 420 W/in3 and a maximum efficiency of 94 %. Later, another Sigma converter suitable for wide voltage range applications was designed with 700W/in3 and a maximum efficiency of 95 %. Both designs can achieve higher efficiency than the two-stage VRM and all other state-of-art solutions. The challenges associated with the Sigma converter, such as startup and closed loop control were addressed, in order to make it a viable solution for the VRM application. The 48V rack architecture requires regulated 12V output converters for various loads. In this thesis, a regulated LLC is used to design a high-efficiency and power-density 48V bus converter. A novel integration method of the inductor and transformer helps the LLC achieve the required regulation capability with minimum losses, resulting in a converter that can provide 1KW of continuous power with efficiency of 97.8 % and 700 W/in3 power density. This dissertation discusses new power architectures with an optimized design for the 48V rack architectures. With the academic contributions in this dissertation, different conversion architectures can be utilized for 48V VRM solutions that solve all of the challenges associated with it, such as scalability, high-efficiency, high density, and high BW control.
Doctor of Philosophy
With the rapid increase of cloud computing and the high demand for digital content, it is estimated that the power consumption of the IT industry will reach 10 % of the total electric power in the USA by 2020. Multi-core processors (CPUs) and graphics processing units (GPUs) are the key elements in fulfilling all of the digital content requirements but come with a price of more power-hungry processors, driving the power per server rack to 20 KW levels. The need for more efficient power management solutions on the architecture level, down to the converter level, is inevitable. The data center manufacturers have recently adopted a more efficient architecture that supplies a 48V DC server rack distribution instead of a 12V DC distribution to the server motherboard. This helped reduce costs and losses, but as a consequence, raised a challenge in the design of the DC/DC voltage regulator modules (VRM) supplied by the 48V, in order to power the CPU and GPU. In this work, different architectures will be explored for the 48V VRM, and the trade-off between them will be evaluated. The main target is to design the VRM with very high-efficiency and high-power density to reduce the cost and size of the CPU/GPU motherboards. First, a two-stage power conversion structure will be used. The benefit of this structure is that it relies on existing technology using the 12V VRM for powering the CPU. The only modification required is the addition of another converter to step the 48V to the 12V level. This architecture can be easily adopted by industry, with only small modifications required on the system design level. Secondly, a single-stage power conversion structure is proposed that achieves higher efficiency and power density compared to the two-stage approach; however, the structure is very challenging to design and to meet all requirements by the CPU/GPU applications. All of these challenges will be addressed and solved in this work. The proposed architectures will be designed using an optimized magnetic structure. These structures achieve very high efficiency and power density in their designed architectures, compared to state-of-art solutions. In addition, they can be easily manufactured using automated manufacturing processes.

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Craven, Richard M. « A study of secondary winding designs for the two-coil Tesla transformer ». Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14375.

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The multi-order response of the tuned secondary circuit of a Tesla transformer, following impulse excitation from its tuned primary circuit, is presented and analysed at the fundamental resonant frequency and at higher-order mode frequencies. A novel way of modifying the frequency response of the secondary coil is then investigated by utilising a technique normally applied to the design of a certain type of filter known as a helical filter. In general, these are used in radio and microwave frequency circuits in order to pass certain frequencies with little attenuation whilst significantly attenuating other frequencies. Design techniques, developed over several decades, modify and optimise the performance of such filters. The frequency response of the helical filter is modified by altering the geometry of the helical resonator component therein, which is typically in the form of an air-cored single-layer solenoid. A Tesla transformer whose secondary is constructed to be some form of single-layer solenoidal winding resonates at its designed frequency - its fundamental mode - but also at non-integer harmonics (higher-order anharmonic frequencies, also known as overtones). Those multi-order oscillatory voltages and currents energised in the secondary circuit have been identified and measured and research has determined the fundamental and higher-order mode frequencies and amplitudes for various experimental secondary winding configurations derived from helical filter design techniques. Applied to the Tesla transformer secondary winding, such techniques lead to a new design with a performance that is improved by the suppression of higher- order anharmonic frequencies whilst imparting little change to the fundamental response. It is anticipated that this feature will lead to Tesla transformers which exhibit enhanced spectral purity and which will be better suited to use in certain pulsed power applications than conventionally wound designs.

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18

Zheng, Cong. « Loosely Coupled Transformer and Tuning Network Design for High-Efficiency Inductive Power Transfer Systems ». Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52893.

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Transfer signal without wire has been widely accepted after the introduction of cellular technology and WiFi technology, hence the power cable is the last wire that has yet to be eliminated. Inductive power transfer (IPT) has drawn substantial interest in both academia and industry due to its advantages including convenience, nonexistence of cable and connector, no electric shock issue, ability to work under some extreme environment, and so on. After performing thorough literature review of IPT systems, two major drawbacks including low power efficiency and coil displacement sensitivity are identified as the main obstacles that have to be solved in order for these systems to reach full functionality and compete with existing wired solutions. To address the limitations and design challenges in the IPT systems, a detailed electric circuit modeling of individual part of the IPT DC-DC stage is performed. Several resonant DC-AC inverters and output AC-DC rectifiers are compared based on their performance and feasibility in inductive charging applications. Different equivalent circuit models for the loosely coupled transformer (LCT) are derived which allows for better understanding on how power is distributed among the circuit components. Five compensation networks to improve the power transfer efficiency are evaluated and their suitable application occasions are identified. With comprehensive circuit model analysis, the influence of the resonant compensation tank parameters has been investigated carefully for efficient power transfer. A novel tuning network parameters design methodology is proposed based on multiple given requirement such as battery charging profile, geometry constraints and operating frequency range, with the aim of avoiding bifurcation phenomenon during the whole charging process and achieving decent efficiency. A 4-kW hardware prototype based on the proposed design approach is built and tested under different gap and load conditions. Peak IPT system DC-DC efficiencies of 98% and 96.6% are achieved with 4-cm and 8-cm air gap conditions, which is comparable to the conventional plug-in type or wired charging systems for EVs. A long-hour test with real EV batteries is conducted to verify the wireless signal transmission and CC/CV mode seamless transition during the whole charging profile without bifurcation. To reduce the IPT system sensitivity to the gap variation or misalignment, a novel LCT design approach without additional complexity for the system is proposed. With the aid of FEA simulation software, the influence of coil relative position and geometry parameters on the flux distribution and coupling coefficient of the transmitter and receiver is studied from an electromagnetic perspective. An asymmetrical LCT based on the proposed design method is built to compare with a traditional symmetrical LCT. With fixed 10-mm gap and 0 to 40-mm misalignment variation, the coupling coefficient for the symmetrical LCT drops from 0.354 to 0.107, and the corresponding efficiency decrease is 16.6%. The operating frequency variation is nearly 100 kHz to maintain same input/output condition. When employing the proposed asymmetrical LCT, the coupling coefficient changes between 0.312 and 0.273, and the maximum efficiency deviation is kept within 0.67% over the entire 40-mm misalignment range. Moreover, the required frequency range to achieve same operation condition is less than 10 kHz. Lastly, some design considerations to further improve the IPT system efficiency are proposed on the basis of the designed asymmetrical LCT geometry. For given circuit specifications and LCT coupling conditions, determination of the optimal primary winding turns number could help achieve minimal winding loss and core loss. For lower output power, the optimal primary winding turns number tends to be larger compared to that for higher output power IPT system. Two asymmetrical LCT with similar dimension but different number of turns are built and tested with a 100-W hardware prototype for laptop inductive charging. The proposed efficiency improvement methodology is validated by the winding loss and core loss from experimental results.
Ph. D.

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19

Huang, Weixing. « Design of a Radial Mode Piezoelectric Transformer for a Charge Pump Electronic Ballast with High Power Factor and Zero Voltage Switching ». Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31818.

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In a conventional electronic ballast for a fluorescent lamp, inductor-capacitor-transformer tank circuit is used. A Piezoelectric Transformer (PT) can potentially be used to replace such a tank circuit to save space and cost. In the past, ballast design using a PT requires selecting a PT from available samples which are normally not matched to specific application and therefore resulting in poor performance. In this thesis, a design procedure was proposed for designing a PT tailored for a 120-V 32-W electronic ballast with high power factor, high efficiency and Zero-Voltage-Switching (ZVS) of the inverter transistors that drive the lamp. This involves selection of PT materials, determination of geometries and the number of physical layers of the PT. A radial mode piezoelectric transformer prototype based on this design process was fabricated by Face Electronics Inc. and was tested experimentally, the results showed that the ballast using this custom-made PT achieved high power factor, Zero-Voltage-Switching and a 83% overall efficiency.
Master of Science

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20

Gu, Bin. « Power Converter and Control Design for High-Efficiency Electrolyte-Free Microinverters ». Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/25236.

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Microinverter has become a new trend for photovoltaic (PV) grid-tie systems due to its advantages which include greater energy harvest, simplified system installation, enhanced safety, and flexible expansion. Since an individual microinverter system is typically attached to the back of a PV module, it is desirable that it has a long lifespan that can match PV modules, which routinely warrant 25 years of operation. In order to increase the life expectancy and improve the long-term reliability, electrolytic capacitors must be avoided in microinverters because they have been identified as an unreliable component. One solution to avoid electrolytic capacitors in microinverters is using a two-stage architecture, where the high voltage direct current (DC) bus can work as a double line ripple buffer. For two-stage electrolyte-free microinverters, a high boost ratio dc-dc converter is required to increase the low PV module voltage to a high DC bus voltage required to run the inverter at the second stage. New high boost ratio dc-dc converter topologies using the hybrid transformer concept are presented in this dissertation. The proposed converters have improved magnetic and device utilization. Combine these features with the converter's reduced switching losses which results in a low cost, simple structure system with high efficiency. Using the California Energy Commission (CEC) efficiency standards a 250 W prototype was tested achieving an overall system efficiency of 97.3%. The power inversion stage of electrolyte-free microinverters requires a high efficiency grid-tie inverter. A transformerless inverter topology with low electro-magnetic interference (EMI) and leakage current is presented. It has the ability to use modern superjunction MOSFETs in conjunction with zero-reverse-recovery silicon carbide (SiC) diodes to achieve ultrahigh efficiency. The performance of the topology was experimentally verified with a tested CEC efficiency of 98.6%. Due to the relatively low energy density of film capacitors compared to electrolytic counterparts, less capacitance is used on the DC bus in order to lower the cost and reduce the volume of electrolyte-free microinverters. The reduced capacitance leads to high double line ripple voltage oscillation on DC bus. If the double line oscillation propagates back into the PV module, the maximum power point tracking (MPPT) performance would be compromised. A control method which prevents the double line oscillation from going to the PV modules, thus improving the MPPT performance was proposed. Finally, a control technique using a single microcontroller with low sampling frequency was presented to effectively eliminate electrolyte capacitors in two-stage microinverters without any added penalties. The effectiveness of this control technique was validated both by simulation and experimental results.
Ph. D.

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21

Freitag, Christian [Verfasser], et T. [Akademischer Betreuer] Leibried. « Magnetic Properties of Electrical Steel, Power Transformer Core Losses and Core Design Concepts / Christian Freitag ; Betreuer : T. Leibried ». Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1127140760/34.

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Zhao, Shishuo. « High Frequency Isolated Power Conversion from Medium Voltage AC to Low Voltage DC ». Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/74969.

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Modern data center power architecture developing trend is analyzed, efficiency improvement method is also discussed. Literature survey of high frequency isolated power conversion system which is also called solid state transformer is given including application, topology, device and magnetic transformer. Then developing trend of this research area is clearly shown following by research target. State of art wide band gap device including silicon carbide (SiC) and gallium nitride (GaN) devices are characterized and compared, final selection is made based on comparison result. Mostly used high frequency high power DC/DC converter topology dual active bridge (DAB) is introduced and compared with novel CLLC resonant converter in terms of switching loss and conduction loss point of view. CLLC holds ZVS capability over all load range and smaller turn off current value. This is beneficial for high frequency operation and taken as our candidate. Device loss breakdown of CLLC converter is also given in the end. Medium voltage high frequency transformer is the key element in terms of insulation safety, power density and efficiency. Firstly, two mostly used transformer structures are compared. Then transformer insulation requirement is referred for 4160 V application according to IEEE standard. Solid insulation material are also compared and selected. Material thickness and insulation distance are also determined. Insulation capability is preliminary verified in FEA electric field simulation. Thirdly two transformer magnetic loss model are introduced including core loss model and litz wire winding loss model. Transformer turn number is determined based on core loss and winding loss trade-off. Different core loss density and working frequency impact is carefully analyzed. Different materials show their best performance among different frequency range. Transformer prototype is developed following designed parameter. We test the developed 15 kW 500 kHz transformer under 4160 V dry type transformer IEEE Std. C57.12.01 standard, including basic lightning test, applied voltage test, partial discharge test. 500 kHz 15 kW CLLC converter gate drive is our design challenge in terms of symmetry propagation delay, cross talk phenomenon elimination and shoot through protection. Gate drive IC is carefully selected to achieve symmetrical propagation delay and high common mode dv/dt immunity. Zero turn off resistor is achieved with minimized gate loop inductance to prevent cross talk phenomenon. Desaturation protection is also employed to provide shoot through protection. Finally 15 kW 500 kHz CLLC resonant converter is developed based on 4160V 500 kHz transformer and tested up to full power level with 98% peak efficiency.
Master of Science

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23

Hashimoto, Kazuki. « Analysis and Design of Air-Core Transformer Based on Internal Magnetic Flux Density Distribution for High-Frequency Power Converter ». Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263662.

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Xu, Ye. « Kilowatt Three-phase Rotary Transformer Design for Permanent Magnet DC Motor with On-rotor Drive System ». Thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-27781.

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The aim of this thesis is to design a kilowatt three-phase step-down rotary transformer for a permanent magnet DC motor. The permanent magnet DC motor has an on-rotor drive system, and therefore requiring a power supply that can transfer power to its drive unit without mechanical contact. The rotary transformer has a detached magnetic coupling structure that qualifies it as a potential method for the wireless power transfer. This thesis studies the rotary transformer as a static device, focusing on its core loss. By using a transient finite element analysis of COMSOL Multiphysics and an iron loss prediction model, the rotary transformer was optimized in terms of efficiency and power density for the on-rotor drive system through proper material selection and geometry exploration. After this, a mechanical design, which based on a literature review of the influences of manufacturing processes on electrical steels, was proposed for realizing the core fabrication and the rotary transformer assembly. The results show that the rotary transformer can step down 400 V/50 Hz three-phase voltage to 13.15V in a Delta-wye connection and output 1.17kW power over an air-gap of 0.3mm with 95.94% overall efficiency. The proposed mechanical design enables the transformer to minimize the core loss and the manufacturing cost. Without using resonant inductive coupling, this transformer design simplifies the power supply for the motor, thereby decreasing the motor manufacturing and maintenance cost.

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Wang, Shen. « Design and Analysis of a Low-Power Low-Voltage Quadrature LO Generation Circuit for Wireless Applications ». Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/39301.

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The competitive market of wireless communication devices demands low power and low cost RF solutions. A quadrature local oscillator (LO) is an essential building block for most transceivers. As the CMOS technology scales deeper into the nanometer regime, design of a low-power low-voltage quadrature LO still poses a challenge for RF designers. This dissertation investigates a new quadrature LO topology featuring a transformer-based voltage controlled oscillator (VCO) stacked with a divide-by-two for low-power low-voltage wireless applications. The transformer-based VCO core adopts the Armstrong VCO configuration to mitigate the small voltage headroom and the noise coupling. The LO operating conditions, including the start-up condition, the oscillation frequency, the voltage swing and the current consumption are derived based upon a linearized small-signal model. Both linear time-invariant (LTI) and linear time-variant (LTV) models are utilized to analyze the phase noise of the proposed LO. The results indicate that the quality factor of the primary coil and the mutual inductance between the primary and the secondary coils play an important role in the trade-off between power and noise. The guidelines for determining the parameters of a transformer are developed. The proposed LO was fabricated in 65 nm CMOS technology and its die size is about 0.28 mm2. The measurement results show that the LO can work at 1 V supply voltage, and its operation is robust to process and temperature variations. In high linearity mode, the LO consumes about 2.6 mW of power typically, and the measured phase noise is -140.3 dBc/Hz at 10 MHz offset frequency. The LO frequency is tunable from 1.35 GHz to 1.75 GHz through a combination of a varactor and an 8-bit switched capacitor bank. The proposed LO compares favorably to the existing reported LOs in terms of the figure of merit (FoM). More importantly, high start-up gain, low power consumption and low voltage operation are achieved simultaneously in the proposed topology. However, it also leads to higher design complexity. The contributions of this work can be summarized as 1) proposal of a new quadrature LO topology that is suitable for low-power low-voltage wireless applications, 2) an in-depth circuit analysis as well as design method development, 3) implementation of a fully integrated LO in 65 nm CMOS technology for GPS applications, 4) demonstration of high performance for the design through measurement results. The possible future improvements include the transformer optimization and the method of circuit analysis.
Ph. D.

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26

Singh, Rahul. « Design Techniques for Frequency Reconfigurability in Multi-Standard RF Transceivers ». Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1185.

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Compared to current single-standard radio solutions, multi-standard radio transceivers enable higher integration, backward compatibility and save power, area and cost. The primary bottleneck in their realization is the development of high-performance frequency-reconfigurable RF circuits. To that end, this research introduces several CMOS-integrated, transformer-based reconfigurable circuit techniques whose effectiveness is validated through measurements of designed transceiver front-end low-noise (LNA) and power amplifier (PA) prototypes. In the first part, the use of high figure-of-merit phase-change (PC) based RF switches in the reconfiguration of CMOS LNAs in the receiver front-end is proposed. The first reported demonstration of an integrated, PC-switch based, dual-band (3/5 GHz) reconfigurable CMOS LNA with transformer source degeneration and designed in a 0.13 μm process is presented. In the second part, a frequency-reconfigurable CMOS transformer combiner is introduced that can be reconfigured to have similar efficiencies at widely separated frequency bands. A 65-nm CMOS triple-band (2.5/3/3.5 GHz) PA employing the reconfigurable combiner was designed. In the final part of this work, the use of transformer coupled-resonators in mm-wave LNA designs for 28 GHz bands was investigated. To cover contiguous and/or widely-separated narrowband channels of the emerging 5G standards, a 65-nm CMOS 24.9-32.7 GHz wideband multi-mode LNA using one-port transformer coupled-resonators was designed. Finally, a 25.1-27.6 GHz tunable-narrowband digitally-calibrated merged LNA-vector modulator design employing transformer coupled-resonators is presented that proposes a compact, differential quadrature generation scheme for phased-array architectures.

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Prasai, Anish. « Methodologies for Design-Oriented Electromagnetic Modeling of Planar Passive Power Processors ». Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34164.

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The advent and proliferation of planar technologies for power converters are driven in part by the overall trends in analog and digital electronics. These trends coupled with the demands for increasingly higher power quality and tighter regulations raise various design challenges. Because inductors and transformers constitute a rather large part of the overall converter volume, size and performance improvement of these structures can subsequently enhance the capability of power converters to meet these application-driven demands. Increasing the switching frequency has been the traditional approach in reducing converter size and improving performance. However, the increase in switching frequency leads to increased power loss density in windings and core, with subsequent increase in device temperature, parasitics and electromagnetic radiation. An accurate set of reduced-order modeling methodologies is presented in this work in order to predict the high-frequency behavior of inductors and transformers. Analytical frequency-dependent expressions to predict losses in planar, foil windings and cores are given. The losses in the core and windings raise the temperature of the structure. In order to ensure temperature limitation of the structure is not exceeded, 1-D thermal modeling is undertaken. Based on the losses and temperature limitation, a methodology to optimize performance of magnetics is outlined. Both numerical and analytical means are employed in the extraction of transformer parasitics and cross-coupling. The results are compared against experimental measurements and are found to be in good accord. A simple near-field electromagnetic shield design is presented in order to mitigate the amount of radiation. Due to inadequacy of existing winding technology in forming suitable planar windings for PCB application, an alternate winding scheme is proposed which relies on depositing windings directly onto the core.
Master of Science

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Hofmann, Oldřich. « Řiditelný spínaný zdroj 0-1000 V / 100 W ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-318178.

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The thesis deals with the design and construction of a switching power supply with output voltage adjustable from 0 to 1200 V and rated power of 120 W, which will be used to replace the existing high voltage power supply for the irreversible electroporation (IRE) device developed at UVEE FEEC BUT. The thesis focuses on a basic description of the IRE device, a description of usable converter topologies and a selection of the best topology for the required purpose. The selection of the control circuit concept and its design are also integral parts of the thesis. The final part of the thesis contains the assembly of the power supply and the measurement verifying its function.

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Danekar, Abhishek V. « Analysis and Design of High-Frequency Soft-Switching DC-DC Converter for Wireless Power Charging Applications ». Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1493990400812363.

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Kaya, Mehmet Can. « Design, Implementation, And Control Of A Two&amp ». Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610106/index.pdf.

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In this thesis a two-stage AC/DC/DC power converter is designed and implemented. The AC/DC input stage of the converter consists of the two&
#8211
phase interleaved boost topology employing the average current mode control principle. The output stage consists of a zero voltage switching phase shifted full bridge (ZVS&
#8211
PS&
#8211
FB) DC/DC converter. For the input stage, main design goals are obtaining high input power factor, low input current distortion, and well regulated output dc voltage, and obtaining these attributes in a power converter with high power density. For the input stage, the interleaved structure has been chosen in order to obtain reduced line current ripple and EMI, reduced power component stresses, and improved power density. The control of the pre&
#8211
regulator is provided by utilizing a new commercial monolithic integrated circuit, which provides interleaved continuous conduction mode power factor correction (PFC). The output stage is formed by utilizing the available prototype hardware of a ZVS&
#8211
PS&
#8211
FB DC/DC converter and mainly the system integration and controller design and implementation studies have been conducted. The converter small signal model is derived and utilizing its transfer function and employing voltage loop control, the output voltage regulator has been designed. The output voltage controller is implemented utilizing a digital signal processor (DSP). Integrating the AC/DC preregulator and DC/DC converter, a laboratory AC/DC/DC converter system with high overall performance has been obtained. The overall system performance has been verified via computer simulations and experimental results obtained from laboratory prototype.

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Ali, Ammar H. A. « Design and Implementation of Radio Frequency Power Feeding Networks for Antenna Array Applications : Simulation and Measurements of Multiport, Equal and Unequal, Fixed and Reconfigurable Radio Frequency Power Feeding Networks for Narrow and Ultra-Wideband Applications ». Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17447.

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Power dividers are vital components and widely used in radio technology, such as antenna arrays, power amplifiers, multiplexers and mixers. A good example is the well-known Wilkinson power divider with its distinctive feeding network characteristics. A comprehensive review indicated that limited research is carried out in the area of planar multiport and reconfigurable power dividers in terms of the power levels between output ports. The main objectives of this work were to develop a small size power divider, a planer multi-output ports power divider and a power divider with a reconfigurable power division ratio. These power dividers were designed to operate over either an ultra-wideband frequency (3.1-10.6 GHz) or WLAN bands (2.4 or 5.2 GHz). A novel multi-layered topology solved the complexity of interconnecting isolation resistors by introducing an additional layer below the ground layer. The prototype was fabricated and tested to validate the results. The measurements and simulation were in good agreement. Finally, a novel uniplanar power divider with reconfigurable output power level difference was developed. The configurability feature was achieved by tuning the quarter wave transformer using one varactor diode. The power divider was applied to improve a full duplex system cancellation performance at the receiver element caused by interference from in-site transmitting antennas. This study investigated fixed power dividers, multi-output power dividers and reconfigurable power dividers. The measurements validated by the simulation results and applications proved the designed power dividers could be used in practical applications.
Higher Committee for Education Development (HCED), Iraq

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32

Xie, Hailian. « On Power-system Benefits, Main-circuit Design, and Control of StatComs with Energy Storage ». Doctoral thesis, Stockholm : Skolan för elektro- och systemteknik, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10302.

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Fouineau, Alexis. « Méthodologies de Conception de Transformateurs Moyenne Fréquence pour application aux réseaux haute tension et réseaux ferroviaires ». Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1256/document.

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Les Transformateurs Moyenne Fréquence (TMF) sont une technologie innovante par rapport aux transformateurs basse fréquence, avec la promesse d’une réduction de volume et d’une augmentation du rendement. Cette thèse s’intéresse en particulier à leur conception pour des applications haute tension forte puissance, telles que les réseaux haute tension et moyenne tension à courant continu, ainsi que les réseaux ferroviaires. Dans ces applications, les TMF sont utilisés au sein de convertisseurs pouvant générer des contraintes spécifiques à prendre en compte durant leur conception : signaux non-sinusoïdaux, tension de polarisation, valeurs d’inductances cibles. De plus, les choix technologiques actuellement disponibles pour la réalisation des TMF sont nombreux, et aucun de ces choix ne fait actuellement consensus quelle que soit l’application visée. Des tendances ont pu être identifiées à l’aide d’un outil de classification des designs de TMF issus de la littérature. Ainsi, les technologies les plus prometteuses ont été sélectionnées et retenues pour la suite. A partir de ces technologies, une méthodologie de conception permettant de concevoir et comparer rapidement et ce de façon semi-automatique des TMF avec différents choix technologiques a été mise en place. Elle est constituée de trois étapes : pré-design, design analytique et validation. Le design analytique complet du TMF avec différents choix technologiques est réalisé à l’aide d’un outil de conception automatisée développé durant cette thèse, que nous avons nommé SUITED (SUpergrid Institute TransformEr Design). Cette méthodologie requiert des modèles et données pour chacun des composants et phénomènes du TMF. Concernant le noyau magnétique, une revue et une sélection de modèles issus de la littérature ont été effectuées pour l’évaluation de l’inductance magnétisante et des pertes magnétiques. De plus, des caractérisations magnétiques ont permis de mettre en évidence l’impact de certains procédés technologiques sur les niveaux de pertes de noyaux magnétiques en matériau nanocristallin, qui est un excellent candidat pour les TMF. Au niveau des bobinages, des modèles analytiques pour calculer le champ magnétique, l’inductance de fuite et les effets de peau et de proximité ont été développés et comparés avec ceux de la littérature ainsi que des simulations. Ces nouveaux modèles s'avèrent obtenir une meilleure précision sur les géométries de TMF considérées que ceux de la littérature. De plus, une nouvelle méthode d’évaluation des capacités parasites de bobinages à spires rectangulaires a été mise en place et validée avec succès. Des schémas thermiques équivalents ont été identifiés pour différentes géométries de TMF. Les résistances thermiques de conduction, convection et radiation sont calculées à partir de modèles détaillés. En particulier, l’anisotropie des matériaux est prise en compte pour la conduction thermique, et les coefficients de convection sont évalués via des corrélations différentes pour chaque face du TMF. Les schémas thermiques sont ensuite résolus de façon itérative et analytique pour prendre en compte les non-linéarités des résistances thermiques tout en optimisant le temps de calcul nécessaire. Enfin, l’ensemble de la méthodologie de conception mise en place a été appliqué sur trois cas d’études correspondant à des applications cibles : haute tension, moyenne tension et ferroviaire. Les résultats obtenus montrent effectivement la performance et la nécessité de cette approche
Medium Frequency Transformers (MFT) are an innovative technology compared to low frequency transformers, with the promise of reduced volume and increased efficiency. This PhD thesis focuses in particular on their design for high voltage, high power applications, such as high voltage and medium voltage DC networks, as well as railway networks. In these applications, MFTs are used in converters that can generate specific constraints to be taken into account during their design: non-sinusoidal signals, polarization voltage, target inductance values. Moreover, the technological choices currently available for the realization of MFTs are numerous, and there is currently no consensus on any technology for any given application. Trends could be identified using a tool to classify MFT designs from the literature. Thus, the most promising technologies were selected and retained for the future. Based on these technologies, a design methodology was developed to quickly and semi-automatically design and compare MFTs with different technological choices. It consists of three steps: pre-design, analytical design, and validation. The complete analytical design of the MFT with different technological choices is carried out using an automated design tool developed during this thesis, named SUITED (SUpergrid Institute TransformEr Design). This methodology requires models and data for each of the components and phenomena of the MFT. Concerning the magnetic core, a review and selection of models from the literature were carried out for the evaluation of the magnetizing inductance and magnetic losses. In addition, magnetic characterizations have made it possible to highlight the impact of certain technological processes on the levels of loss of magnetic cores made of nanocrystalline material, which is an excellent candidate for MFTs. Concerning the windings, analytical models to calculate the magnetic field, leakage inductance and skin and proximity effects were developed and compared with those in the literature and simulations. These models are proving to be more accurate on the MFT geometries considered. On top of that, a new method for evaluating the parasitic capacitances of windings with rectangular turns has been successfully implemented and validated. Thermal networks have been identified for the different MFT geometries. The thermal resistances of conduction, convection and radiation are calculated from detailed models. In particular, the anisotropy of materials is taken into account for thermal conduction, and the convection coefficients are evaluated via different correlations for each face of the MFT. The thermal networks are then solved iteratively and analytically to take into account the non-linearity of the thermal resistances while optimizing the required computation time. Finally, this entire design methodology was applied to three case studies corresponding to the target applications: high voltage, medium voltage and rail. The results obtained do show the performance and necessity of this approach

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Rashid, S. M. Shahriar. « Design and Heterogeneous Integration of Single and Dual Band Pulse Modulated Class E RF Power Amplifiers ». The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543505207173487.

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Mills, Kathy Ann. « Multiliteracies : a critical ethnography : pedagogy, power, discourse and access to multiliteracies ». Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16244/1/Kathy_Mills_Thesis.pdf.

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The multiliteracies pedagogy of the New London Group is a response to the emergence of new literacies and changing forms of meaning-making in contemporary contexts of increased cultural and linguistic diversity. This critical ethnographic research investigates the interactions between pedagogy, power, discourses, and differential access to multiliteracies, among a group of culturally and linguistically diverse learners in a mainstream Australian classroom. The study documents the way in which a teacher enacted the multiliteracies pedagogy through a series of mediabased lessons with her year six (aged 11-12 years) class. The reporting of this research is timely because the multiliteracies pedagogy has become a key feature of Australian educational policy initiatives and syllabus requirements. The methodology of this study was based on Carspecken's critical ethnography. This method includes five stages: Stage One involved eighteen days of observational data collection over the course of ten weeks in the classroom. The multiliteracies lessons aimed to enable learners to collaboratively design a claymation movie. Stage Two was the initial analysis of data, including verbatim transcribing, coding, and applying analytic tools to the data. Stage Three involved semi-structured, forty-five minute interviews with the principal, teacher, and four culturally and linguistically diverse students. In Stages Four and Five, the results of micro-level data analysis were compared with macro-level phenomena using structuration theory and extant literature about access to multiliteracies. The key finding was that students' access to multiliteracies differed among the culturally and linguistically diverse group. Existing degrees of access were reproduced, based on the learners' relation to the dominant culture. In the context of the media-based lessons in which students designed claymation movies, students from Anglo-Australian, middle-class backgrounds had greater access to transformed designing than those who were culturally marginalised. These experiences were mediated by pedagogy, power, and discourses in the classroom, which were in turn influenced by the agency of individuals. The individuals were both enabled and constrained by structures of power within the school and the wider educational and social systems. Recommendations arising from the study were provided for teachers, principals, policy makers and researchers who seek to monitor and facilitate the success of the multiliteracies pedagogy in culturally and linguistically diverse educational contexts.

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36

Mills, Kathy Ann. « Multiliteracies : a critical ethnography : pedagogy, power, discourse and access to multiliteracies ». Queensland University of Technology, 2006. http://eprints.qut.edu.au/16244/.

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The multiliteracies pedagogy of the New London Group is a response to the emergence of new literacies and changing forms of meaning-making in contemporary contexts of increased cultural and linguistic diversity. This critical ethnographic research investigates the interactions between pedagogy, power, discourses, and differential access to multiliteracies, among a group of culturally and linguistically diverse learners in a mainstream Australian classroom. The study documents the way in which a teacher enacted the multiliteracies pedagogy through a series of mediabased lessons with her year six (aged 11-12 years) class. The reporting of this research is timely because the multiliteracies pedagogy has become a key feature of Australian educational policy initiatives and syllabus requirements. The methodology of this study was based on Carspecken's critical ethnography. This method includes five stages: Stage One involved eighteen days of observational data collection over the course of ten weeks in the classroom. The multiliteracies lessons aimed to enable learners to collaboratively design a claymation movie. Stage Two was the initial analysis of data, including verbatim transcribing, coding, and applying analytic tools to the data. Stage Three involved semi-structured, forty-five minute interviews with the principal, teacher, and four culturally and linguistically diverse students. In Stages Four and Five, the results of micro-level data analysis were compared with macro-level phenomena using structuration theory and extant literature about access to multiliteracies. The key finding was that students' access to multiliteracies differed among the culturally and linguistically diverse group. Existing degrees of access were reproduced, based on the learners' relation to the dominant culture. In the context of the media-based lessons in which students designed claymation movies, students from Anglo-Australian, middle-class backgrounds had greater access to transformed designing than those who were culturally marginalised. These experiences were mediated by pedagogy, power, and discourses in the classroom, which were in turn influenced by the agency of individuals. The individuals were both enabled and constrained by structures of power within the school and the wider educational and social systems. Recommendations arising from the study were provided for teachers, principals, policy makers and researchers who seek to monitor and facilitate the success of the multiliteracies pedagogy in culturally and linguistically diverse educational contexts.

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37

Senturk, Osman Selcuk. « Series Active Filter Design, Control, And Implementation With A Novel Load Voltage Harmonic Extraction Method ». Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608819/index.pdf.

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Series Active Filters (SAF) are designed for harmonic isolation and load voltage regulation of single-phase and three-phase voltage harmonic source type nonlinear loads. The novel Absolute Value Method (AVM) for load voltage harmonic extraction is proposed and applied in the control algorithm of SAF. The SAF compensated systems are represented by simplified linear models such that SAF controller gains can be easily determined. Harmonic isolation and load voltage regulation performances of 2.5 kW single-phase and 10 kW three-phase SAF compensated systems are evaluated by detailed simulations. Laboratory prototype single-phase and three-phase SAFs and loads are designed and manufactured. Digital signal processor based control platform is employed. Exclusive laboratory tests are conducted. Via laboratory experiments and simulations it is shown that AVM yields superior harmonic isolation and load voltage regulation performance compared to the conventional low/high pass filtering method. Theory, simulations, and experiments are well correlated and illustrate the feasibility of the proposed method.

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38

Pereira, Albert Manuel. « Conception de Transformateurs Moyennes Fréquences : application aux convertisseurs DC-DC haute tension et forte puissance ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1326.

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Le transport et la distribution de l'énergie électrique sont traditionnellement réalisés en alternatif (50 Hz ou 60 Hz), un des éléments-clés de ces infrastructures est le transformateur de puissance. Ce dernier est utilisé depuis plus d'un siècle et donc sa conception est maîtrisée (avec des rendements très élevés, supérieurs à 99 %). Depuis quelques années, la part des énergies renouvelables est en constante augmentation. Bien souvent, la production des énergies renouvelables est éloignée des centres de consommation. Or, le transport en courant continu sous haute tension (HVDC) sur de grandes distances est plus rentable. Dans ce cas, nous avons besoin de convertisseurs de puissance fonctionnant pour certains avec des Transformateurs Moyennes Fréquences (TMF) entre 1 kHz et quelques dizaines de kilohertz. Dans ces applications, la recherche du rendement maximal est primordiale. L'augmentation de la fréquence de fonctionnement a pour effet bénéfique de diminuer l'encombrement d'un transformateur. Cependant un certain nombre de problèmes vont apparaître avec cette augmentation. Nous pouvons citer : les pertes dans les conducteurs et dans le circuit magnétique sont liées à la fréquence ; le type de bobinages (fil de Litz et feuillard) et les matériaux magnétiques (ferrites et nanocristallins) en moyennes fréquences sont différents de ceux utilisés en 50 Hz ; le refroidissement est plus complexe car la densité de puissance volumique est plus élevée... Ainsi dans cette thèse, nous avons mis en place une méthodologie de conception afin de maîtriser au mieux le dimensionnement d'un TMF avec un compromis précision et coût de calculs. Nous avons identifié les modèles (analytiques et numériques) susceptibles d'être utilisés pour estimer les performances d'un TMF. Deux TMF d'une puissance de 180 kVA et de 1 kVA ont été dimensionnés, fabriqués et testés afin de mettre en évidence le domaine de validité et d'ajuster les différents modèles. Ce travail nous a permis de mettre en place une méthodologie de conception allant des spécifications du convertisseur jusqu'à la simulation de celui-ci avec le modèle du transformateur dimensionné. Nous avons mis en évidence : l'influence de paramètres technologiques sur l'élévation de la résistance pour des bobinages de type feuillard et l'influence de paramètres technologiques sur les propriétés magnétiques des matériaux nanocristallins. Ce travail de thèse a été réalisé avec le groupe « Matériaux du Génie Electrique » du laboratoire Ampère et financé par l'institut pour la transition énergétique SuperGrid Institute
The transmission and distribution of electric power is normally made by ac networks (50 Hz or 60 Hz), where one of the key elements of this infrastructure is the power transformer; used for more than a century, its design is very well understood, with a level of operating efficiency normally greater than 99%. In recent years, the share of renewable energy has been increasing. Often times the energy generated from renewable sources is produced far from consumption centers, and so transportation in the form of high voltage direct current (HVDC) over long distances is more profitable, due to the lower losses seen than with HVAC after a certain length of transmission line. In this case, we need power converters operating with Medium Frequency Transformers (MFT) from 1 kHz to tens of kilohertz. For these applications, the research of their maximum efficiency in operation is paramount. Increasing the transformer operating frequency has the beneficial effect of reducing its size. However, a number of problems will appear with this frequency increase, such as: the increase in the losses in the conductors and the magnetic circuit that are related to the frequency; the less well understood winding type (Litz wire and foil) and magnetic materials (ferrites and nanocrystalline) in the MF that are different from those used at 50 Hz; the cooling is more complex because the power density is higher, etc. In this thesis, a design methodology was developed in order to optimise the design of MFTs with respect to the compromise between accuracy and the length of calculations. In addition, analytical and numerical models were identified that can be used to accurately estimate the performance of an MFT. Furthermore, two MFTs (apparent power: 180 kVA and 1 kVA, respectively) were sized, manufactured and tested in order to demonstrate the domain of validity of the models, and also for optimisation of the different models. This work has enabled the development of a design methodology using the converter specifications and build a simulation with complete model of the transformer, which can then be used to validate an MFT design. We have highlighted: the influence of the technological parameters on the rise of resistance in the foil coils and the influence of the technological parameters on the magnetic properties of nanocrystalline materials. This work was performed with the group "Materials for Electrical Engineering" Ampère laboratory and funded by the Institute for Energy Transition SuperGrid Institute

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Киведжі, Василь Володимирович, et Vasyl Kyvezhdi. « Реконструкція системи електропостачання селища міського типу ». Bachelor's thesis, Тернопільський національний технічний університет імені Івана Пулюя, кафедра електричної інженерії, Тернопіль, Україна, 2021. http://elartu.tntu.edu.ua/handle/lib/35312.

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В сучасних умовах стає складним і відповідальним завданням виконання проектів систем електропостачання сільськогосподарського призначення. Прийняття проектних рішень має безпосередній вплив на загальну кількість і об’єм монтажних робіт, безпечність і зручність експлуатації електротехнічного обладнання. Проектування систем електропостачання для певних об’єктів в основ-ному залежить від існуючих класів напруги в цьому об'єкті. Клас напруги, який знаходиться в експлуатації, в більшості випадків визначає капітало-вкладення на проектування об'єкта і кількісні показники втрат потужності та електричної енергії під час експлуатації. Визначальне рішення щодо вибору класу напруги мережі зазвичай приймають на основі проведеного техніко-економічного порівняння варіантів системи електропостачання. Базовими вимогами до розробки проектів систем електропостачання вважаються їхня економічність та надійність електропостачання споживачів. Надійність електропостачання можна забезпечити вибором сучасного досконалого електричного обладнання, силових трансформаторів, кабельної і провідникової продукції, правильно розрахованого електричного навантаження для нормальних і аварійних режимів номінальним навантаженням елементів системи, а також використання системи структурного резервування та секціонування електромережі. Побудова на даний час електричних мереж, встановлення підвищу-вальних і понижувальних підстанцій в системі електропостачання, як правило, становить великі матеріальні витрати. Відповідно, при проектуванні необхідно проводити скрупульозний аналіз економічності прийнятих проект- них рішень та вибраних режимів роботи всіх елементів систем електро-постачання.
У кваліфікаційній роботі розроблено проект реконструкції системи електро¬поста¬чан¬ня селища міського типу Ільниця Закарпатської області. Метою кваліфікаційної роботи є зменшення втрат по¬тужності і зниження відхилення напруги за рахунок побудови трансформаторної під¬станції глибокого вводу на напругу 35 кВ та поетапної реконструкції розпо¬дільчої мережі 10 кВ. Кваліфіка¬ційна робота складається зі вступу, 4 розділів і загальних висновків. У вступі визначено актуальність роботи, мету, завдання та практичну значимість роботи. У першому розділі розглянуто переваги і труднощі впровадження розпо¬діленої генерації. У другому розділі визначено розрахункові навантаження та проведено розрахунок втрат потужності і відхилення напруги. У третьому розділі виконано вибір місця розташування нової трансформаторної підстанції, розроб¬ле¬ні умови забезпечення норм надійності споживачів, вибрано перетини електрич¬них проводів з перевіркою їх на термічну стійкість. У четвертому розділі розглянуті основні аспекти охорони праці та безпеки життєдіяльності при роботі в електроустановках, виконано розрахунок пристрою блискавкозахисту підстанції та заземлюючих пристроїв.
In the qualification work the project of reconstruction of the power supply system of Ilnytsia urban-type settlement of Zakarpattia region was developed. The purpose of the qualification work is to reduce power losses and reduce voltage deviations by building a transformer substation of deep input voltage of 35 kV and the gradual reconstruction of the 10 kV distribution network. Qualification work consists of an introduction, 4 sections and general conclusions. The introduction identifies the relevance of the work, purpose, objectives and practical significance of the work. The first section discusses the advantages and difficulties of implementing distributed generation. In the second section, the design loads are determined and the calculation of power losses and voltage deviations is performed. In the third section the choice of the location of the new transformer substation is made, the conditions of ensuring the norms of consumer reliability are developed, the cross sections of electric wires are selected with their check for thermal stability. In the fourth section the main aspects of labor protection and safety at work in electrical installations are considered, the calculation of the lightning protection device of the substation and grounding devices is performed.
ЗМІСТ ПЕРЕЛІК СКОРОЧЕНЬ 6 ВСТУП 6 1 АНАЛІТИЧНИЙ РОЗДІЛ 8 1.1 Проблеми електропостачання сільськогосподарських споживачів 8 1.2 Розподілена генерація в системі електропостачання 12 1.3 Переваги і труднощі впровадження розподіленої генерації 13 1.4 Висновки до розділу 1 15 2 РОЗРАХУНКОВИЙ РОЗДІЛ 16 2.1 Аналіз району електропостачання 16 2.2 Визначення розрахункових навантажень 21 2.3 Розрахунок втрат потужності і відхилення напруги 24 2.4 Висновки до розділу 2 30 3 ПРОЕКТНО-КОНСТРУКТОРСЬКИЙ РОЗДІЛ 31 3.1 Вибір місця розташування ПС 35/10 кВ та трансформаторів 31 3.2 Розробка умов забезпечення норм надійності споживачів 38 3.3 Вибір перетинів електричних проводів 41 3.4 Перевірка вибраних перетинів проводів на термічну стійкість 41 3.5 Висновки до розділу 3 45 4 БЕЗПЕКА ЖИТТЄДІЯЛЬНОСТІ ТА ОСНОВИ ОХОРОНИ ПРАЦІ 46 4.1 Основні задачі в галузі охорони праці 46 4.2 Розрахунок пристрою блискавкозахисту підстанції 51 4.3 Розрахунок заземлюючих пристроїв 46 4.4 Висновки до розділу 4 46 ЗАГАЛЬНІ ВИСНОВКИ 53 ПЕРЕЛІК ПОСИЛАНЬ 55

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Ковальчук, Володимир Іванович, et Volodymyr Kovalchuk. « Забезпечення надійності роботи системи електропостачання підприємства виготовлення будівельних матеріалів ». Master's thesis, Тернопільський національний технічний університет імені Івана Пулюя, кафедра електричної інженерії,Тернопіль, Україна, 2020. http://elartu.tntu.edu.ua/handle/lib/33190.

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Розраховані МСЗ і захист від перевантаження генераторів із застосуванням автоматичних вимикачів серії ВА07 виробництва компанії IEK. Для захисту трансформатора були розраховані МСЗ, СВ і захист від перевантаження із застосуванням мікропроцесорного пристрою Sepam Т-20. Для захисту живлячої кабельної лінії був розрахований МСЗ на пристрої Sepam S-20, також для кабельної лінії передбачили захист від замикань на землю. Для керування автоматичним введенням резерву прийняли до встановлення 2 незалежні блоки управління БУАВР.
У кваліфікаційній роботі магістра здійснено розробку заходів для забезпечення надійності роботи системи електропостачання підприємства виготовлення будівельних матеріалів. Виконано модернізацію електропостачання цього підприємства із застосуванням автономних джерел живлення, розрахунок цехових електричних навантажень, розрахунок і вибір внутрішньоцехових мереж, а також живлячих ліній, вибір комутаційно-захисної апаратури, вибір релейного захисту живлячих елементів, розрахунок контуру захисного заземлення та освітлення.
In the qualification work of the master, measures were developed to ensure the reliability of the power supply system of the building materials manufacturer. Modernization of power supply of this enterprise with the use of autonomous power supplies, calculation of shop electrical loads, calculation and selection of in-shop networks, as well as supply lines, selection of switching and protection equipment, selection of relay protection of supply elements, calculation of protective earthing circuit and lighting.
ЗМІСТ ВСТУП 6 1 АНАЛІТИЧНИЙ РОЗДІЛ 9 1.1 Аналіз когенераційних установок 9 1.1.1 Когенераційні газові електростанції 9 1.1.2 Когенерація енергії 9 1.1.3 Когенераційні міні ТЕЦ 10 1.1.4 Газові і дизельні електростанції 11 1.3 Переваги застосування газопоршневої установки Сaterpillar 11 1.4 Досвід адаптації цифрових терміналів РЗА до українських умов 13 1.5 Коротка характеристика об’єкту проектування 13 1.6 Висновки до розділу 1 16 2 РОЗРАХУНКОВО-ДОСЛІДНИЦЬКИЙ РОЗДІЛ 17 2.1 Розрахунок електричних навантажень підприємства 17 2.1.1 Розрахунок цеху, що детально розраховується 17 2.1.2 Розрахунок електричних навантажень по цехах 20 2.1.3 Розрахунок освітлювального навантаження 21 2.1.4 Розрахунок картограми електричних навантажень 22 2.2 Розподіл електроенергії 25 2.2.1 Побудова схеми електропостачання 25 2.2.2 Вибір генераторних установок 26 2.2.3 Вибір трансформатора 27 2.2.4 Вибір перерізу кабелів і шинопроводів 28 2.2.5 Перевірка електричної мережі на втрати напруги 30 2.2.6 Вибір комутаційно-захисних апаратів 32 2.3 Висновки до розділу 2 34 3 ПРОЕКТНО-КОНСТРУКТОРСЬКИЙ РОЗДІЛ 35 3.1 Вибір основного електрообладнання РП 0,4 кВ 35 3.1.1 Вибір вимикачів 35 3.1.2 Вибір жорстких шин 36 3.1.3 Вибір ізоляторів 37 3.1.4 Вибір трансформаторів струму 37 3.2 Розрахунок струмів короткого замикання 39 5 3.2.1 Розрахунок струму короткого замикання кола генератора 39 3.2.2 Розрахунок струму короткого замикання кола трансформатора 44 3.2.3 Перевірка вибраного обладнання по умові КЗ 47 3.3 Розрахунок зовнішнього електропостачання 48 3.3.1 Вибір КЛ 48 3.3.2 Вибір електроустаткування РП 10 кВ. 48 3.4 Розрахунок власних потреб 51 3.5 Вибір релейного захисту і автоматики 52 3.5.1 Розрахунок захисту генераторів 52 3.5.2 Розрахунок захисту трансформатора 54 3.5.3 Розрахунок захисту живлячої кабельної лінії 57 3.5.4 Розрахунок уставок АВР 61 3.6 Розрахунок штучного освітлення 62 3.6.1 Розрахунок внутрішнього освітлення 62 3.6.2 Розрахунок зовнішнього освітлення 64 3.7 Висновки до розділу 3 66 4 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ 67 4.1 Забезпечення електробезпеки обслуговуючого персоналу 67 4.2 Розрахунок захисного заземлення 68 4.3 Порядок дії працівників підприємства під час виникнення пожежі 71 ЗАГАЛЬНІ ВИСНОВКИ 74 ПЕРЕЛІК ПОСИЛАНЬ 76

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Pešl, Jiří. « Spínaný zdroj se spínáním při nulovém napětí ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242009.

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Diploma thesis describes the design of an switched mode power supply with switching at zero voltage for driving the anode of Anode-layer type ion source. First aim of thesis is ion sources and specialy Anode-layer type of ion source in detail. Main aim of thesis are important aspects of the design of switching mode power supply, which comes later the detailed construction of an switched mode power supply with output voltage 2800 V at output power 2800 W.

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Tran, Tuan Vu. « Problèmes combinatoires et modèles multi-niveaux pour la conception optimale des machines électriques ». Phd thesis, Ecole Centrale de Lille, 2009. http://tel.archives-ouvertes.fr/tel-00425590.

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La conception des machines électriques a une longue tradition et l'approche " business as usual " est un processus itératif d'essais et d'erreur, certes convergent mais nécessairement stoppé prématurément, car trop couteux. Un perfectionnement récent a consisté à remplacer les prototypes et les maquettes par des prototypes virtuels, entièrement numériques, comme ceux fournis par la méthode des éléments finis. Néanmoins, le procédé s'arrête toujours sur une frustration car le concepteur n'est jamais sûr d'avoir exploré complètement l'espace de conception qui s'offre à lui. La démarche de conception optimale se propose d'améliorer ce processus en le guidant, c'est-à-dire en proposant une méthodologie, et en l'automatisant, c'est-à-dire en proposant des outils logiciels. Mais dans cette démarche apparaissent de nombreuses difficultés. Ainsi, les objectifs généraux de cette thèse sont multiples. Il s'agit de définir des problèmes d'optimisation spécifiques représentatifs des choix structurels et d'élaborer des benchmarks de référence : discret, multiphysique, multidisciplinaire, multi-objectif et multi-niveaux. Ensuite, il faut rechercher, adapter et qualifier les méthodes d'optimisation les mieux à même de résoudre ces problèmes. Enfin, les différentes méthodes d'optimisation proposées sont implantées et testées de façon à prouver leur efficacité et leur adaptation. Un objectif secondaire mais important est de les capitaliser et diffuser les connaissances élaborées

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Rauls, Mark. « Analysis and design of high frequency co-axial winding power transformers ». 1992. http://catalog.hathitrust.org/api/volumes/oclc/25984988.html.

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Thesis (M.S.)--University of Wisconsin--Madison, 1992.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 99-100).

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Odendaal, Willem Gerhardus. « A generic approach for the modelling of high power density magnetic components ». Thesis, 2012. http://hdl.handle.net/10210/6822.

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D.Ing.
Transformer design is an art which spans a century. Although the basic transformer has changed little over this period, the challenges that face high frequency power transformer designers today have grown considerably. Increasing frequency and power density and decreasing size and profile are among the most important. Eddy currents, controlling circuit behaviour and minimising losses are important aspects of design, and close attention is paid to heat removal and cooling. Modern transformers are no longer limited to certain shapes and sizes; choosing the topology and optimising the shape is often part of the design process. For each aspect of design, numerous modelling techniques exist for analysing transformer behaviour, with varying degrees of complexity. A common feature of optimisation techniques is the large number of variables and interdependent functions that relate different aspects, from the associated behavioural models, to one another. In this study, this complexity is reduced by integrating the individual analytical models for transformer behaviour. Since a convenient thermal model for high frequency transformers does not exist at present, a new thermal reference model is devised and verified. It is specifically suited to high frequency transformer applications and design, and practical sets of reference data are provided for a few ferrite materials and for copper. Transformer losses are considered next, with special attention given to eddy current analysis techniques. New formulations of eddy current solutions are given, with extensions of the orthogonality principle for skin- and proximity effects and superposition thereof. An investigation of leakage impedance design as a function of frequency scaling follows. The relationship between leakage reactance voltage drop as a function of frequency scaling by dividing a monolithic transformer into distributed elements is considered, and the results are applied to two case studies of a 35kVA transformer for a plasma burner application. A new model, the generic proportionality model, applies the thermal referenCe model to scaling of transformer parameters. A case study is also presented, demonstrating the relationships that exist between design parameters and performance functions. Another generic model, the scant model, is introduced, which integrates the thermal reference model into optimisation of transformer shape. It uses a limited number of functional and form parameters, and is applicable to a wide variety of geometries. Two case studies, demonstrate the effects of varying the shape of a rectangular configuration on derating factors.

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Murthy, G. S. Ramana. « Design Of Transformers And Inductors At Power-Frequency - A Modified Area-Product Method ». Thesis, 1999. http://etd.iisc.ernet.in/handle/2005/1641.

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Chu, Yu-Ting, et 朱侑庭. « Design of Power Line Carrier Systems for Connectivity Identification of Distribution Transformers and Customers ». Thesis, 2008. http://ndltd.ncl.edu.tw/handle/52217456629019568308.

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碩士
國立高雄應用科技大學
電機工程系博碩士班
96
With the voluminous distribution transformers and complexity of low voltage lines between transformer and the customer metering box, the traditional way to identify the connectivity of transformer and customers by disconnecting the customer service will raise serious complaints of power interruption. The objective of this thesis is to investigate the signal transmission characteristics of power line carrier (PLC) used in distribution systems. The PLC based testing system will be developed to support the identification of distribution transformer and all the customers served. The residential building, commercial and office building, the building mix of residential and commercial customers, are selected as the testing sites for PLC testing. With this testing system developed, distribution engineers can identify the connectivity of each distribution transformer and the customers, which can enhance the practicability of OMS system, the efficiency of outage restoration and the transformer load management. This objective will also study the power line carrier signal transmission for Open Y-Open Delta of distribution transformers. A proper PLC chip will be selected and the circuits of signal coupling module, signal transceiver module are going to be integrated as a single PLC based testing unit. The factory testing will be conducted to verify the performance fine tune the PLC unit. After completing the testing, the field acceptance test of the PLC unit developed will be conducted to verify the effective-ness of the system for the identification of all customers served by each transformer. The PLC testing unit will provide a very effective tool for Taipower engineers to support the connectivity verification of transformer and customers, which will be very important to enhance the operation and maintenance of distribution systems.

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Tsong-ShingLee et 李宗勳. « A Study of Piezoelectric Transformers and Resonance Circuit Design Aided with Wireless Power Transfer Capability ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/23298230082802533027.

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博士
國立成功大學
電機工程學系
103
With a progress of technology, the merits of wireless energy transfer system is increasingly applied and witnessed in power transmission and energy conversion devices. In the mean time, the concept of plasma discharging through the firing of high-voltage source for cleaning and sterilization is widely adopted in industries and families. Therefore, this dissertation is aimed to investigate the application of wireless power transfer for high-voltage power converter applications, where the frequency-tracking control, the feedback mechanism, the resonant topology, and the design process are also included. The thesis starts with the improvement of wireless power delivers, in which the inductive coil magnetic coupling and distance change that affecting the transmission efficiency are both analyzed. This is followed by the investigation of the resonance compensation structure and parameters, by which the feedback mechanism of phase-loop locked strategy is implemented to achieve the frequency-tracking of the system. Next, considering that the inductive coil design plays a critical role in the wireless power transfer, the dissertation proposes a manufacturing process and design approach, where the suitable values of coil for the applications under different source power, transmission gaps, and coupling coefficients can be calculated with ease. To verify the feasibility of this system, theoretical analyses are made and mathematical models are formulated along with hardware realizations. Test results indicate that the proposed method can adjust the operating frequency to promote the power transmission efficiency while the output voltage can be well stabilized. The coil design and resonance circuits suggested in this dissertation also ensure that the expected amount of power can be transferred in a wireless way, and the soft-switching is fulfilled. These outcomes are served as useful references for wireless power transfer applications. Subsequently, in consideration of the plasma-driven circuit often employs the bulky magnetic inductors and capacitors as resonant elements to induce the high voltage, these complex circuit designs along with feedback device would affect the operating performance, restricting the industry competition for a further circuit development. Hence, this dissertation proposes a power converter with PT-based resonant architectures to replace conventional inductor-capacitor resonant tanks. The modular capacity operation made in this study helps increase the output power along with a higher flexibility. Experimental results indicate that the output voltage can be effectively increased to achieve the goal of plasma discharging, while the dimension of driving circuit is reduced and the resonant circuit design is simplified. Next, in order to widely extend the application fields of wireless power transfer system for high-voltage power converters, this dissertation proposes a prototype design of contactless charging system platform. The dissertation includes an operating frequency correction method and a compensator design of converters such that sufficient amount of power can be supplied and the output voltage can be maintained for plasma-driven circuits. In addition, the circuit has added a battery module to reach the requirement of a portable plasma generator. Conclusively, from all of control strategies and system architectures proposed in this dissertation, the overall circuit system is seen to possess the merits of electrical isolation and electrode insulation, while the design process can be largely simplified. The research results gained from this dissertation can be also served as the reference of industrial design and development for plasma-driven systems. Keywords: wireless power transfer, frequency-tracking, inductive coil design, plasma-driven circuit, piezoelectric transformer, resonant circuit, feedback mechanism.

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48

Lin, Tung-Bin, et 林桐斌. « Design of Substation Facility Maintenance and Management System Incorporated with Fault Diagnosis Method for Power Transformers Based on Hybrid Fuzzy Dissolved Gas Analysis ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/pug39n.

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碩士
國立臺北科技大學
電機工程系研究所
98
To expedite Taiwan Power Company’s (TPC’s) engineers recording inspection results of primary substation facilities and to affirm the inspection works have been finished. The “Substation Facility Maintenance and Management System (SFMMS)” is designed for TPC to integrate data of all substation facility into database and to increase and update data as well as security management by Server. The SFMMS also provides the functions such as filtering and analysis of inspection data, acquisition of facility information, and printing of different tables for maintenance and statistics. SFMMS will also generate the tables with the formats complied with the one on the Utility Facility Inspection Web Page designed by the Energy Bureau, Ministry of Economics, to either automatically upload the inspection data to the website of Energy Bureau or provide convenience for inspection engineers to input the corresponding inspection data in terms of the formats from the Energy Bureau on the Utility Facility Inspection Web Page. In addition, referring to TCG (Total Combustible Gas), the DGA(Dissolved Gas Analysis) methods established by IEEE, IEC and EJA are integrated and utilized with Fuzzy Inference to develop into the “Hybrid Fuzzy Dissolved Gas Analysis” and apply to SFMMS to complete the DGA module on Web Page.

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Shadmand, Mohammad. « A Design-Oriented Framework to Determine the Parasitic Parameters of High Frequency Magnetics in Switching Power Supplies using Finite Element Analysis Techniques ». Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11082.

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Magnetic components, such as inductors and transformers, have important effects on the efficiency and performance of switching power supplies; their parasitic properties directly impact the high frequency properties which can cause lot-to-lot variation or unanticipated and non-ideal operation. They are also amongst the most problematic components to design, often requiring numerous design-prototype-test interactions. The electrostatic and electromagnetic analysis of wound components has become more important recently to predict their performance and frequency behavior. Accurate prediction and design of winding parasitic parameters of leakage inductance and winding capacitance for high frequency inductors and transformers in switching power supplies is fundamental to improve performance, lower cost, and speed time to market. This thesis presents a methodology and process to obtain accurate prediction of the inter- and intra-winding capacitances of high frequency magnetic components. Application examples considered are a single-winding choke, a coupled inductor filter, and a multi-winding transformer. Analytical approach for determination of parasitic capacitances in high frequency magnetic components will be covered also. Comparison of the FEA results using JMAG with experimental and empirical formula results show good agreement, supporting the method as a model-based design tool with the potential to significantly reduce the design-prototype-test cycle commonly needed with sophisticated magnetic designs.

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Huang, Ying-Hsiang, et 黃盈翔. « Design of Low Power VCO Using Transformer Technique ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/80960348958395071645.

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碩士
國立雲林科技大學
電子與資訊工程研究所
97
The circuit design is oriented to the goal of shrinking area、low power dissipation and high data transmission. Let all system components can be integrated on a chip. Hence our thesis aim at shrinking the area of LC tank 、promoting the Q factor of inductor and increasing negative-resistance, so as to arrive at the target of shrinking area and low power dissipation. In our thesis, we talk about the theory and architecture of oscillator, and we will use the LC oscillator which is the most popular for analysis. The chip fabrication of VCO circuit is made by TSMC 0.18um CMOS 1P6M process. Finally, the efficiency of the circuit was demonstrated by measurement. The first chip was designed a low power and wide tuning range CMOS LC voltage controlled oscillator (VCO) with back-source transformer feedback. The measurement result of the VCO exhibits a tuning range of 22% form 4.41GHz to 5.49GHz at the supply voltage of 0.8 V. The figure of merit, core power consumption and output power are -186.36 dBc/Hz, 2.4mW and -4.65 dBm, respectively. The phase noise is -116.36 dBc/Hz at the operation frequency of 4.9 GHz. The second chip was designed a low phase noise and wide tuning range CMOS LC voltage controlled oscillator (VCO) with gate-drain transformer feedback. The measurement result of the VCO exhibits a tuning range of 28% form 4.39GHz to 5.8GHz at the supply voltage of 0.8 V. The figure of merit, core power consumption and output power are -193.1 dBc/Hz, 4.4mW and -2.3dBm, respectively. The phase noise is -124.3dBc/Hz at the operation frequency of 5.8 GHz.

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Thèses sur le sujet « Power transformers design »

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