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1
Jacobs, Joseph [Verfasser]. "Multi-Phase Series Resonant DC-to-DC Converters / Joseph Jacobs." Aachen : Shaker, 2006. http://d-nb.info/1166513211/34.
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2
Warnasooriya, Nilanthi. "Quantitative phase imaging microscopy with multi-wavelength optical phase unwrapping." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002637.
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Rakgati, Edward Tshitshiri. "Torque Performance of Optimally Designed Multi-Phase Reluctance DC Machines." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1174.
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Qin, Ruiyang. "Study on Three-level DC/DC Converter with Coupled Inductors." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73169.
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High power multi-level converters are deemed as the mainstay power conversion technology for renewable energy systems including the battery storage system, PV farm and electrical vehicle charge station. This thesis is focused on the study of three-level DC/DC converter with multi-phase interleaved structure, with coupled and integrated magnetics to achieve high power density. The proposed interleaved phased legs offer the benefit of output current ripple reduction, while inversed coupled inductors can suppress the circulating current between phase legs. Compared with conventional non-interleaving three-level DC/DC converter with non-coupling inductors, both inductor current ripple and output current ripple are largely reduced by interleaving with inverse-coupled inductors.
Because of the non-linearity of the inductor coupling, the equivalent circuit model is developed for the proposed interleaving structure. The model identifies the existence of multiple equivalent inductances during one switching cycle. A combination of them determines the inductor current ripple and dynamics of the system. By virtue of inverse coupling and means of controlling the coupling coefficients, one can minimize the current ripple and the unwanted circulating current.
To further reduce the magnetic volume, the four inductors in two-phase three-level DC/DC converter are integrated into one common structure, incorporating the negative coupling effects. The integrated magnetic structure can effectively suppress the circulating current and reduce the inductor current ripple and it is easy to manufacture. This thesis provides an equivalent circuit model to facilitate the design optimization of the integrated system.
A prototype of integrated coupled inductors is assembled with nano-crystalline C-C core and powder block core. It is tested with both impedance analyzer and single pulse tester, to guarantee proper mutual inductance for inductor current ripple and output current ripple target. With a two-phase three-level DC/DC converter hardware, the concept of integrated coupled inductors is verified, showing its good performance in high-voltage, high-power conversion applications.Master of Science
5
Mazumder, Sudip K. "Nonlinear Analysis and Control of Standalone, Parallel DC-DC, and Parallel Multi-Phase PWM Converters." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/28690.
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Applications of distributed-power systems are on the rise. They are already used in telecommunication power supplies, aircraft and shipboard power-distribution systems, motor drives, plasma applications, and they are being considered for numerous other applications. The successful operation of these multi-converter systems relies heavily on a stable design. Conventional analyses of power converters are based on averaged models, which ignore the fast-scale instability and analyze the stability on a reduced-order manifold. As such, validity of the averaged models varies with the switching frequency even for the same topological structure.
The prevalent procedure for analyzing the stability of switching converters is based on linearized smooth averaged (small-signal) models. Yet there are systems (in active use) that yield a non-smooth averaged model. Even for systems for which smooth averaged models are realizable, small-signal analyses of the nominal solution/orbit do not provide anything about three important characteristics: region of attraction of the nominal solution, dependence of the converter dynamics on the initial conditions of the states, and the post-instability dynamics. As such, converters designed based on small-signal analyses may be conservative. In addition, linear controllers based on such analysis may not be robust and optimal. Clearly, there is a need to analyze the stability of power converters from a different perspective and design nonlinear controllers for such hybrid systems.
In this Dissertation, using bifurcation analysis and Lyapunov's method, we analyze the stability and dynamics of some of the building blocks of distributed-power systems, namely standalone, integrated, and parallel converters. Using analytical and experimental results, we show some of the differences between the conventional and new approaches for stability analyses of switching converters and demonstrate the shortcomings of some of the existing results. Furthermore, using nonlinear analyses we attempt to answer three fundamental questions: when does an instability occur, what is the mechanism of the instability, and what happens after the instability?
Subsequently, we develop nonlinear controllers to stabilize parallel dc-dc and parallel multi-phase converters. The proposed controllers for parallel dc-dc converters combine the concepts of multiple-sliding-surface and integral-variable-structure control. They are easy to design, robust, and have good transient and steady-state performances. Furthermore, they achieve a constant switching frequency within the boundary layer and hence can be operated in interleaving or synchronicity modes. The controllers developed for parallel multi-phase converters retain many of the above features. In addition, they do not require any communication between the modules; as such, they have high redundancy. One of these control schemes combines space-vector modulation and variable-structure control. It achieves constant switching frequency within the boundary layer and a good compromise between the transient and steady-state performances.Ph. D.
6
Liu, Changrong. "A Novel High-Power High-Efficiency Three-Phase Phase-Shift DC/DC Converter for Fuel Cell Applications." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26048.
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Fuel cells are a clean, high-efficiency source for power generation. This innovative technology is going to penetrate all aspects in our life, from utility distributed power, transportation applications, down to power sources for portable devices such as laptop computer and cell phones. To enable the usage of fuel cell, developing power converters dedicated for fuel cells becomes imminent.
Currently, the full-bridge converter is the dominating topology in high power dc/dc applications. Although multiphase converters have been proposed, most of them are dealing with high input-voltage systems, and their device characteristic is not suitable for a low voltage source such as a fuel cell. For a high power fuel cell system, high voltage conversion ratios and high input currents are the major obstacles to achieving high-efficiency power conversions. This dissertation proposes a novel 3-phase 6-leg dc/dc power converter with transformer isolation to overcome these obstacles. Major features of the proposed converter include: (1) Increase converter power rating by paralleling phases, not by paralleling multiple devices; (2) Double the output voltage by transformer delta-wye connection, thus lowering the turns-ratio; (3) Reduce the size of output filter and input dc bus capacitor with interleaved control; (4) Achieve Zero-Voltage Zero-Current Switching (ZVZCS) over a wide load range without auxiliary circuitry. High conversion efficiency above 96% is verified with different measurement approaches in experiments.
This dissertation also presents the power stage and control design for the proposed converter. Control design guideline is provided and the design result is confirmed with both simulation and hardware experiments. When using the fuel cell for stationary utility power applications, a low-frequency ripple interaction was identified among fuel cell, dc/dc converter and dc/ac inverter. This low frequency ripple tends to not only damage the fuel cell, but also reduce the source capability. This dissertation also investigates the mechanism of ripple current propagation and exploits the solutions. A linearized ac model is derived and used to explain the ripple propagation. An active ripple reduction technique by the use of the current loop control is proposed. This active current loop control does not add extra converters or expensive energy storage components. Rather, it allows a reduction in capacitance because the ripple current flowing into the capacitor is substantially reduced, and less capacitance can be used while maintaining a clean dc bus voltage. The design process and guideline for the proposed control is suggested, and the effectiveness of this active control is validated by both simulation and experimental results.Ph. D.
7
Mupambireyi, Ushindibaba. "Modelling, analysis and control of multi-phase electronically commutated DC machines : an enabling topology for DC converter fed networks." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/101516/.
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Multiphase electronically commutated dc machine is a new non-conventional machine and converter topology aimed at dc power generation and delivery systems. This thesis presents a detailed analysis of two multiphase electronically commutated dc machine topologies, firstly, the two level topology then the multilevel topology. Electronic current commutation processes in these topologies are analysed and electrical machine parameters that influence current commutation and the design of the electronic commutator are exposed. The behaviour of the power electronic commutator circuit is shown to be tightly coupled to that of the electrical machine connected to it and to be inductively dominated during current commutation. Performance, efficiency, footprint and cost are all affected by design considerations arising from the interaction of electronic commutator switching devices and electrical machine. Thus there is an incentive to ensure that the designs of power electronic commutator circuits and electrical machines are matched, allowing the requirements of the system as a whole to be satisfied. Since these machine and converter topologies depart from the conventional machine and converter topologies, an alternative modelling approach that lends itself well to modelling of the machine and its associated power electronics is presented. The models are used to evaluate the operational attributes of the machine and its associated electronic commutator power electronic circuit and the proposed control schemes. Results from two prototype laboratory drives built to practically access the viability and fully characterise the operational behavior of these topologies together with the simulation results are presented. Conclusions are drawn concerning the proposed topologies and their associated control strategies.
8
Zhu, Huiyu. "New Multi-Phase Diode Rectifier Average Models for AC and DC Power System Studies." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/30188.
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More power semiconductors are applying to the aircraft power system to make the system smaller, lighter and more reliable. Average models provide a good solution to system simulation and can also serve as the basis to derive the small signal model for system-level study using linear control theory.
A new average modeling approach for three-phase and nine-phase diode rectifiers with improved ac and dc dynamics is proposed in this dissertation. The key assumption is to model the load current using its first-order Taylor Series expansion throughout the entire averaging time span. A thorough comparison in the time domain is given of this model and two additional average models that were developed based on different load current assumptions, using the detailed switching models as the benchmark. The proposed average model is further verified by experimental results.
In the frequency domain, the output impedance of a nine-phase diode rectifier is derived, and the sampling effect in the average model is investigated by Fourier analysis. The feeder's impedance before the rectifier is modeled differently in the output impedance in contrast in the equivalent commutation inductance.
The average model is applied to the resonance study in a system composed of a synchronous generator, a nine-phase diode rectifier and a motor drive. The Thevenin's and Norton's equivalent circuits are derived to construct a linearized system. The equivalent impedance are derived from the average models, and the source are obtained from the switching circuit by short-circuit or open-circuit. Transfer functions are derived from the harmonic sources to the bus capacitor voltage for resonance study. The relationship between the stability and the resonance is analyzed, and the effect of controllers on the resonance is investigated.
Optimization is another system-level application of the average model. A half-bridge circuit with piezoelectric actuator as its load is optimized using genetic algorithm. The optimization provides the possibility to design the actuator and its driving circuit automatically.Ph. D.
9
Kim, Jong Wan. "Back to Back Active Power Filter for Multi-Generator Power Architecture with Reduced dc-link Capacitor." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96638.
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Multi-pulse converters have been widely used for a multi-megawatt scale power generating system to comply with harmonic regulations. Among all types of multi-pulse converters, a 12-pulse converter is the most widely used due to the simple structure, which consists of a delta-delta and a delta-wye phase-shift transformer pair and it effectively mitigates undesirable harmonics from the nonlinear load.
In the early 2000s, a shunt type passive front-end for a shipboard power system was proposed. By shunting the two gensets with 30° phase angle difference, a single phase-shift transformer effectively eliminates 5th and 7th harmonics. It achieves a significant size and weight reduction compared to a 12-pulse converter while keep the comparable harmonic cancellation performance. Recently, a hybrid type front-end was proposed. On top of the passive front-end, 3 phase active power filter was added and an additional harmonic cancellation was achieved to further eliminate 11th and 13th harmonics. However, the performance of both the passive and hybrid type front-end are highly dependent on the size of the line reactor in ac mains.
A back to back active power filter is proposed in this dissertation to replace the phase-shift transformer in the multi-generator power architecture. The proposed front-end does not include phase-shift transformer and the size and the weight of the overall front-end can be significantly reduced. Due to the active harmonic compensation, the back to back front-end achieves better power quality and the line reactor dependency is improved. The number of required dc-link capacitors is reduced by half by introducing a back to back configuration and the capacitor size is reduced by adjusting the phase angle difference of genset to cancel out the most significant voltage harmonics in the shared dc-link bus.
The overview of the existing shunt type front-end is provided and the concept of back to back active power filter is validated by simulation and prototype hardware. The comparison between existing front-end and the proposed front-end is provided to highlight the superior performance of back to back active front-end. The dc-link bus current and voltage ripple analysis is provided to explain the dc-link ripple reduction mechanism.Doctor of Philosophy
The transportation electrification has gained more and more attention due to its smaller carbon dioxide emission, better fuel efficiency. The recent advances in power devices, microcontrollers, and transducers accelerate the electrification of transportation. This trend is shown in the propulsion system in marine transport as well and the electric propulsion system has been widely used to meet the strict environmental regulations. However, the non-linear circuit components such as capacitor and diode in the electric propulsion system draw non-linear current and significantly deteriorate power quality and lead to critical problems such as reduced life span of circuit components Accordingly, a front-end is required to improve power quality. Also, it is desired to have compact and lightweight front-end for installation flexibility and fuel efficiency improvement. In this dissertation, several front-ends using a phase-shift transformer are reviewed and a detailed analysis is provided to help understand the harmonic cancellation principle of the existing front-end through equivalent circuit analysis, quantitative analysis, and a phasor diagram representation. Based on the analysis of the existing front-ends and shipboard power architecture, lightweight and high-performance front-end is proposed and verified by simulation and prototype hardware. The performance, size comparison between existing front-end and the proposed front-end is provided to show the advantage of the proposed front-end.
10
Louganski, Konstantin P. "Modeling and Analysis of a Dc Power Distribution System in 21st Century Airlifters." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35514.
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A DC power distribution system (PDS) of a transport aircraft was modeled and analyzed using MATLAB/Simulink software. The multi-level modeling concept was used as a modeling approach, which assumes modeling subsystem of the PDS at three different levels of complexity. The subsystem models were implemented in Simulink and combined into the whole PDS model according to certain interconnection rules. Effective modeling of different scenarios of operation was achieved by mixing subsystem models of different levels in one PDS model. Linearized models were obtained from the nonlinear PDS model for stability analysis and control design.
The PDS model was used to examine the system stability and the DC bus power quality under bidirectional power flow conditions. Small-signal analysis techniques were employed to study stability issues resulting from subsystem interactions. The DC bus stability diagram was proposed for predicting stability of the PDS with different types of loads without performing an actual stability test based on regular stability analysis tools. Certain PDS configurations and operational scenarios leading to instability were identified. An analysis of energy transfer in the PDS showed that a large energy storage capacitor in the input filter of a flight control actuator is effective for reduction of the DC bus voltage disturbances produced by regenerative action of the actuator. However, energy storage capacitors do not provide energy savings in the PDS and do not increase its overall efficiency.Master of Science
11
Young, Kurt A. "COMPARATIVE ANALYSES OF MULTI-PULSE PHASE CONTROLLED RECTIFIERS IN CONTINUOUS CONDUCTION MODE WITH A TWO-POLE LC OUTPUT FILTER FOR SURFACE SHIP DC APPLICATIONS." Monterey, California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/32924.
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The Navy of tomorrow will require a robust and reconfigurable power system capable of supplying power not only to large high power propulsion loads but to growing combat system loads like high power radar and pulse loads such as rail guns and free-electron lasers. A critical component in such a system is the phase controlled rectifier. As such, the issues associated with the inclusion of a power electronics rectifier need to be addressed. These issues include input Alternating Current (AC) interface requirements, the output Direct Current (DC) load profile, and overall stability in the presence of non-linear loads. Understanding these issues and determining the means of assuring compatibility with a Navy all-electric ship is the focus of this thesis. By using a Simulink model of a variable parameter load, several multiple-pulse count, high power rectifiers were exercised. The Simulink results were compared to the linearized small signal transfer function analysis results. These experiments led to the conclusion that increasing the pulse count and output filtering reduces the input interface current distortion. However, there are tradeoffs in terms of complexity and size of the passive components, and optimization based on source and load specifications is required.
12
Voss, Johannes [Verfasser], Doncker Rik W. [Akademischer Betreuer] De, and H. Alan [Akademischer Betreuer] Mantooth. "Multi-megawatt three-phase dual-active bridge dC-dC converter : extending soft-switching operating range with auxiliary-resonant commutated poles and compensating transformer saturation effects / Johannes Voss ; Rik W. de Doncker, H. Alan Mantooth." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1217788972/34.
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Nonet, Olivier. "Conception d’amplificateurs de puissance haut rendement en technologie MMIC pour applications radiocommunication 5G." Electronic Thesis or Diss., Limoges, 2024. http://www.theses.fr/2024LIMO0037.
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Les réseaux modernes de radiocommunication utilisent des signaux modulés complexes à forte efficacité spectrale et offrent des débits de donnés importants avec en contrepartie, des facteurs de crête élevés. Ce dernier paramètre dégrade fortement le rendement moyen des amplificateurs, la dissipation thermique est de fait augmentée limitant ainsi les perspectives de miniaturisation, de réduction des coûts et de fiabilité des amplificateurs. Ce travail présente la conception d’un amplificateur de puissance RF >40W en bande L/S miniaturisé. Ce composant a spécifiquement été réalisé pour être compatible avec un système d’amélioration de rendement de type suivi d’enveloppe. Pour répondre à ce besoin, une approche de miniaturisation quasi-MMIC en boitier plastique, composée d’une partie active HEMT GaN 0.25µm sur SiC, et de circuits passifs d’adaptation en AsGa (ULRC-20) ont été retenus. Une architecture de suivi d’enveloppe de type multi-phases a ensuite été développée dans le but d’être associée à cet amplificateur et fonctionner avec des signaux modulés 5G complexes, large-bande à forts niveaux de PAPR (>8dB)Modern radio communication networks use complex modulated signals with high spectral efficiency, offering significant data rates. However, this comes at the expense of high peak factors.This latter parameter significantly degrades the average efficiency of amplifiers, leading to increased thermal dissipation, thereby limiting prospects for miniaturization, cost reduction, and reliability of the power amplifier. This work presents the design of an RF power amplifier >40W in the L/S band. This component has been specifically developed to be compatible with an envelope tracking efficiency enhancement system. To meet this requirement, a quasi-MMIC miniaturization approach in a plastic package, comprising a GaN HEMT 0.25µm on SiC active part, and passive adaptation circuits in AsGa (ULRC-20), have been selected. A multi-phase envelope tracking architecture has subsequently been developed to be associated with this amplifier and operate with complex 5G modulated signals, wideband with high PAPR levels (>8dB)
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DIANA, MICHELA. "Tooth-coil wound multiphase synchronous machines." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2713044.
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Nowadays we are witnessing a strong growth in the full electric vehicle market.
In the field of traction the requirements are low weight, small dimensions and low
cost, without renouncing reliability and good performances. The high power density
requirement is pushing the research towards integrated drive solutions. A particular
drive that allows to obtain more insightful integrated solutions is the multi-phase one.
In fact, in multi-phase structures it is possible to realize a converter as a combination
of standard modules with an equal subdivision of the current. The resulting power
electronics modules meet the needs of an integrated solution: smaller and widely
distributed.
Although road electric vehicles primarily adopt 3-phase drives, the multi-phase
version could represent a good alternative not only for its integration capability
but also for other features like reduced weight and volume, high efficiency, low
vibrations and noise, robustness and, overall, fault tolerance. The aim of this thesis is
to investigate a particular category of multiphase machines, characterized by a very
simple structure that allows to match manufacturing and performance standards.
In Chapter 1, the subcategory of multiphase machine object of the investigation
is identified. Considering a simple stator structure, as the tooth-coil wound, a
general algorithm to identify the right stator-rotor coupling in multiphase machine is
presented.
In Chapter 2, an analytical and generalized formulation of the harmonic fields at
the air gap for the multi-n-phase solutions chosen is reported allowing to understand
and quantify the harmonic compensation in the MMF. Starting from the Lorenz
Force Law an analytical formulation of the torque and torque ripple is then proposed.
The model proposed has been then verified by Finite Element Analysis (FEA).
In Chapter 3, the main issues tackled in the design of a nine phase machine are
reported. Between the possible solutions a 9 slot 10 poles PM-inset machine has
been chosen. The chapter reports the evaluation of the performance conducted by the
time stepping FEA. The chapter reports the experimental results that were conducted
on a prototype. A description of the control infrastructure is reported.
In Chapter 4, a simple modulation strategy that allows to reduce the DC-link
stress for a triple-3-phase drive is presented. The analysis of the benefits introduced
by the PWM phase shifting are evaluated by steady state simulations ,using the
software Pspice, in all the possible operating conditions. A worst case approach has
been chosen in order to find the best angle of shifting between carriers to reduce
the DC-link rms current in multi-3-phase drives. The results of the experimental
validation are reported. The same analysis has been extended to sectored multiphase.
In Chapter 5, a mathematical model is proposed in order to evaluate the torque
and the torque ripple in fractional slot tooth-coil wound (TCW) Synchronous Reluctance
(SyR) machines. Considering a generic harmonic field and an ideal SyR rotor,
the rotor magnetic potential is modelled and the torque equations are calculated
starting from the Lorenz Force Law. Time stepping FEA results are reported in order
to verify the formulations.
Appendix A reports the mathematical demonstration that defines the rotor reaction
for an ideal SyR rotor together with the methodologies used to design the SyR
constant permeance rotor.
Appendix B reports the manufacturing process of the machine.
Appendix C reports the COOL-TIE concept: a cooling devices for the electrical
machine compatible with the power electronic integration
15
Khmaladze, Alexander. "Three-dimensional microscopy by laser scanning and multi-wavelength digital holography." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002638.
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Cheng, Sheng-Wen, and 鄭勝文. "Design and Implementation of a Multi-Phase Buck DC-DC Converter for Blade Servers." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/46655847937705213867.
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碩士國立臺灣科技大學
電機工程系
102
In this thesis, a digitally-controlled voltage regulation module (VRM) which is fully compliant with Intel® VR12.5 specifications is implemented. In the presented system, a four-phase buck converter topology is adopted. An IR3581 dual-loop digital multi-phase buck controller is utilized as the digital controller, and IR3578 integrated synchronous buck driver IC is used to implement the power stage. Advantages of using a digital controller and integrated driver chip include fewer peripheral components and high design flexibility. Main features of IR3581 controller include digital compensator design, dynamic phase control (DPC) and adaptive transient algorithm (ATA). DPC automatically adds/drops phases based upon load current, which will improve the converter efficiency at light load condition. ATA based on non-linear digital PWM algorithms can minimize bulk output capacitors. Experimental results validate that the implemented system can meet the Intel® VR12.5 specifications, and the measured efficiency is higher than 94%.
17
Kang, Zhe-Wei, and 康哲維. "Study of a Multi-Phase Isolated DC/DC Converter for PEM Fuel Cell Stacks." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/33731010025977904061.
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碩士國立臺灣科技大學
電子工程系
98
Recently, clean energy resources, such as wind turbines, photovoltaic systems or fuel cells, have been exploited for developing renewable electric power generation systems. Among them, the rapid advances in fuel cell technology have enabled the significant developments in fuel cell power system. The fuel cells feature numerous advantages, such as high energy density, high current output ability, and high-efficiency operation. However, the fuel cell stacks present a low voltage output and a wide range of voltage variations under different load, temperature, humidity and electrochemical reaction conditions. A step-up power converter is therefore applied to obtain a high output voltage from the fuel cell system. A high-performance isolated multi-phase power converter for fuel cell power systems is studied and implemented. A digital controller is also designed to perform the interleaved operation of the paralleled multi-phase power modules. Finally, a 10-kW converter prototype is implemented and tested to verify the feasibility of the studied topology and control strategy.
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Tsai, Chia-Hao, and 蔡家豪. "Study of a 10kW Multi-Phase Digital-Controlled DC/DC Converter for Fuel Cell Applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/c2h6a2.
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碩士國立臺灣科技大學
電子工程系
99
Recently, clean energy resources such as solar cell, wind turbine or fuel cell have been exploited for developing renewable electric power generation systems. The fuel cell is considered as the most clean energy technology. Its major advantages include low noise, low pollution, high efficiency, and easy replacement. However, the fuel cell stacks present low voltage output and wide range of voltage variation. In order to provide load a constant source, a step-up DC-DC converter must be inserted between the fuel cell stack and the load. In this thesis, the adopted circuit topology is the current-fed full-bridge boost converter with secondary voltage-doubler. A digital controller is also designed to coordinate the interleaved parallel operation among the multi-phase power modules. An auxiliary power is used to provide digital signal processor (5V/3A), drive circuit (15V/2A) and the feedback circuit (15V/0.67A). An improved high-performance isolated multi-phase power converter is studied and implemented for fuel cell power systems. Finally, a 10kW DC-DC boost converter is implemented, Experimental results are shown to verify the feasibility of the developed system. A high conversion efficiency over 90% can be achieved.
19
Lin, Li-Chia, and 林立家. "Improved Dual Phase Cross-Coupled Charge Pump Techniques for Selectable Multi-Output DC-DC Converters." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/80030758925497407331.
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碩士國立交通大學
電機與控制工程系所
96
LCD panels are going more and more popular. The applications of the LCD panels are widely spread in our daily life. From the small LCD panels on palmtop entertainment machine and cell phone to the large LCD panels on LCD TV or outdoor display screen. Therefore, the power supply blocks for LCD panels are more and more important. The needs to integrate the power supply block into the LCD driver circuits are rise in great demands. In other words, it is necessary to reduce the size of the power supply block chip and reduce the number of the external components. The power sources for LCD panels need different voltage scale to charge and discharge the liquid crystal capacitors. Among the DC-DC power converters, inductive switching converters need external components as inductors and charge pumps need external components as capacitors. Compare these two external components inductors and capacitors, inductors occupy larger board area than that of capacitors. Besides, LCDs need a negative voltage to discharge the liquid crystal capacitors. It is difficult for Inductive switching converters to generate a negative voltage. Therefore, for cost and area considerations, we use charge pumps to replace inductive switching converters. In this thesis, the ripple of the charge pump is further reduced by an improved double phase cross-coupled charge pump structure. This thesis implements a switchable multi output DC-DC converter utilize improved dual phase cross-coupled charge pumps. The input voltage is a high voltage 10V. The circuit can supply 4 different output voltages, 10V, 20V, -10V and 0V. The maximum current load is 50mA. The chip is simulated and fabricated by TSMC 0.25um 2.5V/5V/12V/40V 1P5M BCD process CMOS technology.
20
Feng, Yi-Hsin, and 馮毅昕. "Three-Phase Multi-Level Y-Y Connection Bi-Directional Series-Series Resonant DC-DC Converter." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9ucj8t.
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碩士國立臺灣科技大學
電子工程系
106
This thesis presents Three-Phase Multi-Level Y-Y connection Bi-Directional Series-Series Resonant DC-DC Converter. The voltage stress of the power switch is equal to half of the input voltage. Therefore, it is suitable for high input-voltage applications, and is easy to choose the power switch device, it also has the benefit of reducing output voltage and current ripple. This article will introduce the principle of Three-Phase Multi-Level Y-Y connection Bi-Directional Series-Series Resonant DC-DC Converter. On secondary side, synchronous rectification is added to reduce the conduction loss, and a digital signal processor DSP is used to control the switching signal to achieve multi-stage voltage equalization control. Finally, a laboratory prototype of Three-Phase Multi-Level Y-Y connection Bi-Directional Series-Series Resonant DC-DC Converter was designed and tested for high-voltage applications. The circuit specifications are 7 kW rated power, 800 V input voltage, and 8.75 A output current. The measured efficiency can be up to 96% under different load conditions.
21
Cao, Ke. "Thermal Management for Multi-phase Current Mode Buck Converters." Thesis, 2011. http://hdl.handle.net/1807/29498.
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The main goal of this thesis is to develop an active thermal management control scheme for multi-phase current mode buck converters in order to improve the long term reliability of the converters. A thermal management unit (TMU) with independent linear compensators for the thermal loops is incorporated into the existing digital controller to regulate the current through
each phase so that equal temperature distribution is achieved across all phases. A lumped parameter thermal model of the multi-phase converter is built as the basis of the TMU.
MATLAB simulation results are used to verify the TMU concept. Experimental results from a
digitally controlled 12 V to 1 V, 50 A, 250 kHz four-phase peak current mode buck converter demonstrate the effectiveness of the proposed thermal management technique in the presence of uneven air flow. The steady-state performance, dynamic transient load performance, effect of gate drive voltage and efficiency measurements are investigated and discussed.
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"Digital Controlled Multi-phase Buck Converter with Accurate Voltage and Current Control." Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.46206.
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abstract: A 4-phase, quasi-current-mode hysteretic buck converter with digital frequency synchronization, online comparator offset-calibration and digital current sharing control is presented. The switching frequency of the hysteretic converter is digitally synchronized to the input clock reference with less than ±1.5% error in the switching frequency range of 3-9.5MHz. The online offset calibration cancels the input-referred offset of the hysteretic comparator and enables ±1.1% voltage regulation accuracy. Maximum current-sharing error of ±3.6% is achieved by a duty-cycle-calibrated delay line based PWM generator, without affecting the phase synchronization timing sequence. In light load conditions, individual converter phases can be disabled, and the final stage power converter output stage is segmented for high efficiency. The DC-DC converter achieves 93% peak efficiency for Vi = 2V and Vo = 1.6V.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2017
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Cheng, Ching-Hsiang, and 鄭景翔. "Novel Isolated Multi-Phase High Step-Up Voltage Ratio DC Converters." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/83727561076548186122.
Full textAbstract:
碩士國立清華大學
電機工程學系
100
High step-up voltage ratio DC converters are widely used in a variety of high voltage applications such as the front-end stages of uninterruptible power systems and distributed energy systems. Also, for safety reasons, galvanic isolation is essential. Although one can use high turns ratio transformer and/or coupling inductors to achieve high step-up voltage ratio, however, the resulting high voltage stress and decreased efficiency are the major drawbacks. Hence, in this thesis, a different approach is employed to achieve high step-up voltage ratio without relying on a high turns ratio transformer and/or coupling inductors. Basically, the major contributions of this thesis may be summarized as follows. Frist, a series of novel isolated two-phase high step-up voltage ratio DC converters are proposed to achieve a voltage gain of , where is isolated transformer turns ratio, is the duty ratio of the converter and . Special features of the proposed converters include less voltage stress of all active switches and diodes, low input current ripples, automatic current sharing among input phases, and higher efficiency. Second, modeling and characteristic analysis of a six times voltage multiplier converter are made in the context. In addition, optimal design of output capactiors is investigated to achieve minimum output voltage ripples. Third, a 400W prototype with 25V input and 400V output is constructed to verify the feasibility of the proposed converter. It is seen that the voltage stress of active switches and diodes are and respectively, and the corresponding European and maximum efficiencies are 93.49% and 95.56% respectively. Also, by adding an active clamped circuit, the resulting efficiencies are raised to 94.73% and 96.04% respectively. Finally, for even higher power levels, the corresponding three-phase and four-phase DC converters with voltage gain are also presented for reference. Keywords：Muti-Phase DC Converter, Isolated Converter, High Step-Up Voltage Ratio, High Efficiency.
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Chang, Bor-Min, and 張博民. "Research of Three-Phase Multi-Pulse AC to DC Diode Rectifiers." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/19582960243031392378.
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碩士國立成功大學
電機工程學系
89
In this thesis, techniques of multi-pulse diode rectifiers are analyzed. The multilevel voltage source converters, the input voltages of the rectifier are modified to approximate sinusoidal waves. As a result, the current flows through the inductor connected between ac source and the rectifier approximates the sinusoidal wave. In phase-shifted multi-pulse converters, transformers or autotransformers are used to change the phases of the input voltages, more than two sets of voltage sources are generated such that the input current harmonic components are reduced. In third harmonic current re-injection techniques, the current is derived from the ripple of the rectified voltage and injected into ac source to compensate the third harmonic current produced by the diode rectifier. Finally, the package software IsSpice is used to simulate and analyze converter topologies.
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Lukic, Zdravko. "Design and Practical Implementation of Advanced Reconfigurable Digital Controllers for Low-power Multi-phase DC-DC Converters." Thesis, 2012. http://hdl.handle.net/1807/33855.
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The main goal of this thesis is to develop practical digital controller architectures for multi-phase dc-dc converters utilized in low power (up to few hundred watts) and cost-sensitive applications. The proposed controllers are suitable for on-chip integration while being capable of providing advanced features, such as dynamic efficiency optimization, inductor current estimation, converter component identification, as well as combined dynamic current sharing and fast transient response.
The first part of this thesis addresses challenges related to the practical implementation of digital controllers for low-power multi-phase dc-dc converters. As a possible solution, a multi-use high-frequency digital PWM controller IC that can regulate up to four switching converters (either interleaved or standalone) is presented. Due to its configurability, low current consumption (90.25 μA/MHz per phase), fault-tolerant work, and ability to operate at high switching frequencies (programmable, up to 10 MHz), the IC is suitable to control various dc-dc converters. The applications range from dc-dc converters used in miniature battery-powered electronic devices consuming a fraction of watt to multi-phase dedicated supplies for communication systems, consuming hundreds of watts.
A controller for multi-phase converters with unequal current sharing is introduced and an efficiency optimization method based on logarithmic current sharing is proposed in the second part. By forcing converters to operate at their peak efficiencies and dynamically adjusting the number of active converter phases based on the output load current, a significant improvement in efficiency over the full range of operation is obtained (up to 25%). The stability and inductor current transition problems related to this mode of operation are also resolved.
At last, two reconfigurable digital controller architectures with multi-parameter estimation are introduced. Both controllers eliminate the need for external analog current/temperature sensing circuits by accurately estimating phase inductor currents and identifying critical phase parameters such as equivalent resistances, inductances and output capacitance. A sensorless non-linear, average current-mode controller is introduced to provide fast transient response (under 5 μs), small voltage deviation and dynamic current sharing with multi-phase converters. To equalize the thermal stress of phase components, a conduction loss-based current sharing scheme is proposed and implemented.
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Hsu, Lan-Ting, and 許嵐婷. "Modeling and Control of a Multi-Phase Step-Up DC/DC Converter with Low Switch Voltage Stress." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/33656679231194366909.
Full textAbstract:
碩士國立清華大學
電機工程學系
96
In recent years, with global energy shortage and strong environmental movements, many countries are encouraging and promoting the development of distributed energy sources such as fuel cells and renewable energies. As important roles in new energy, however, the output voltage of the solar cells and the fuel cells is rather low. Hence, a high step-up dc/dc converter is normally required as an interface to increase voltage for back-end applications. Therefore, emphasis of this thesis is placed on developing a high efficiency and high step-up dc/dc converter for these two new energy systems. Basically, the main contributions of this thesis can be summarized as follows. First, a new high efficiency and high step-up dc/dc converter is proposed. It can effectively reduce the voltage stress of active switches and the output voltage ripple of the converter. Moreover, it is able to maintain rather high efficiency in wide load range. Second, the mathematical model of the proposed converter is derived. According to the model, a close-loop controller is designed to achieve better stability and transient response of the converter. Finally, a 200V/100W laboratory prototype is constructed and corresponding simulations as well as experimental results are provided to verify the feasibility of the proposed converter. It is seen that the resulting efficiency curve can be maintained rather flat and above 93% for a load varied from 40W to 100W. Furthermore, the voltage stress of active switches and the output voltage ripple are 25% and 16.7%, respectively, lower than that of the voltage doubler proposed in 2007.
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CHEN, YUNG-HAN, and 陳永翰. "A High Efficient Switch Mode DC-DC Converter with a Multi-Phase Periodic Shut Down Switch-On-Demand Modulator." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/y7w4k8.
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Luo, Zhixiang. "A multi-featured single-phase utility interface with reduced DC link capacitor for distributed power sources." Thesis, 2004. http://spectrum.library.concordia.ca/8397/1/MR04385.pdf.
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The traditional, regulated electric power systems are based on large power generation plants located far from load centers. In a deregulated market, however, small and environmentally friendly power plants using wind power, photovoltaic cells, fuel cells and micro-turbines can be installed through a given distribution system. This concept of distributed generation tends to reduce the cost of electricity and to reduce or postpone major investments in the transmission system. Many of these small power plants are typically consumer owned and are connected to the utility grid by means of single-phase power electronic voltage source converters. This type of converter that supplies active power to the ac grid can also be controlled to provide active filtering and Var generation, thus enhancing the quality of the power at a given point and providing added value to the distributed power source. This Thesis focuses on the practical issues of a multi-featured single-phase utility interface. It focuses on three important aspects: (1) the management of the low order voltage harmonics present in the dc bus of the interface. (2) The design of fast and robust single phase phase-locked loop for the synchronization of the power interface. (3) A new control circuit for a three-level hysteresis current controller. Finally, a digital signal processor based prototype test circuit that satisfies all the aforementioned functions and allows active power filtering and reactive power compensation is built in the laboratory to demonstrate the effectiveness of the proposed techniques.
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Lin, Ting-Yueh, and 林廷岳. "The Research of Applying Multi-Order Sliding ModeController in Three Phase Brushless DC Motor to RejectDisturbance." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/94516058984458985918.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
105
In this paper, first, we explain the fundamental theory and operation mode of DC motors and brushless DC motors. We explain the six-step square wave drive method of brushless DC motors by using the image and control method PWM (Pulse Width Modulation) drives the motor. Including thr detection method of commutation points, hall sensor detection and sensorless detection. The important part in the paper is current control and rotor speed control using the high-order SMC (Sliding Mode Controller).We use the one-order SMC to control the current and simultaneously use the two-order SMC to control the speed in order to achieve the effect of disturbance rejection. Finally, we simulate the brushless DC motor drive system, including three-phase inverter, pulse width modulation, switching function of Hall sensor and sensorless. We also compare the one-order and two-order sliding mode controller and traditional Proportional Integral Derivative controller by MATLAB/Simulnik simulation. We know the results and verify the feasibility of method to confirm the effective disturbance rejection of instantaneous loading, it can make the rotor speed restore the steady state value in short time, also can avoid over decline of rotor speed .
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"An Inductor Emulator Approach to Peak Current-mode Control in a 4-Phase Buck Regulator." Master's thesis, 2017. http://hdl.handle.net/2286/R.I.46244.
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abstract: High-efficiency DC-DC converters make up one of the important blocks of state-of-the-art power supplies. The trend toward high level of transistor integration has caused load current demands to grow significantly. Supplying high output current and minimizing output current ripple has been a driving force behind the evolution of Multi-phase topologies. Ability to supply large output current with improved efficiency, reduction in the size of filter components, improved transient response make multi-phase topologies a preferred choice for low voltage-high current applications.
Current sensing capability inside a system is much sought after for applications which include Peak-current mode control, Current limiting, Overload protection. Current sensing is extremely important for current sharing in Multi-phase topologies. Existing approaches such as Series resistor, SenseFET, inductor DCR based current sensing are simple but their drawbacks such low efficiency, low accuracy, limited bandwidth demand a novel current sensing scheme.
This research presents a systematic design procedure of a 5V - 1.8V, 8A 4-Phase Buck regulator with a novel current sensing scheme based on replication of the inductor current. The proposed solution consists of detailed system modeling in PLECS which includes modification of the peak current mode model to accommodate the new current sensing element, derivation of power-stage and Plant transfer functions, Controller design. The proposed model has been verified through PLECS simulations and compared with a transistor-level implementation of the system. The time-domain parameters such as overshoot and settling-time simulated through transistor-level
implementation is in close agreement with the results obtained from the PLECS model.Dissertation/Thesis
Masters Thesis Electrical Engineering 2017