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1
Lian, Yiqing. "DC/DC converter for offshore DC collection network." Thesis, University of Strathclyde, 2016. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=26896.
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Large wind farms, especially large offshore wind farms, present a challenge for the electrical networks that will provide interconnection of turbines and onward transmission to the onshore power network. High wind farm capacity combined with a move to larger wind turbines will result in a large geographical footprint requiring a substantial sub-sea power network to provide internal interconnection. While advanced HVDC transmission has addressed the issue of long-distance transmission, internal wind farm power networks have seen relatively little innovation. Recent studies have highlighted the potential benefits of DC collection networks. First with appropriate selection of DC voltage, reduced losses can be expected. In addition, the size and weight of the electrical plant may also be reduced through the use of medium- or high-frequency transformers to step up the generator output voltage for connection to a medium-voltage network suitable for wide-area interconnection. However, achieving DC/DC conversion at the required voltage and power levels presents a significant challenge for wind-turbine power electronics. This thesis first proposes a modular DC/DC converter with input-parallel output-series connection, consisting of full-bridge DC/DC modules. A new master-slave control scheme is developed to ensure power sharing under all operating conditions, including during failure of a master module by allowing the status of master module to be reallocated to another healthy module. Secondly, a novel modular DC/DC converter with input-series-input-parallel output-series connection is presented. In addition, a robust control scheme is developed to ensure power sharing between practical modules even where modules have mismatched parameters or when there is a faulted module. Further, the control strategy is able to isolate faulted modules to ensure fault ride-through during internal module faults, whilst maintaining good transient performance. The ISIPOS connection is then applied to a converter with bidirectional power flow capability, realised using dual-active bridge modules. The small- and large-signal analyses of the proposed converters are performed in order to deduce the control structure for the converter input and output stages. Simulation and experimental results demonstrate and validate the proposed converters and associated control schemes.
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Renström, Ola. "Isolerad DC/DC omvandlare." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-58117.
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Andersson, Martin. "Isolerad DC/DC-omvandlare." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-58119.
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1 SammanfattningCrossControl är ett företag som bland annat tillverkar integrerade datorlösningar. Datorerna drivs normalt med 18-30 VDC och förbrukar som mest 50W. Datorerna säljs till flertalet olika kunder som monterar dem i allt från skogsmaskiner till tåg. I de olika fordonen varierar spänningen i de befintliga elnäten. Detta skapar behovet av att omvandla spänningen till en nivå som datorerna klarar av. En sådan apparat kallas DC/DC-omvandlare. Spänningsomvandling kan utföras genom linjär reglering eller med hjälp av switchteknik. Målet för detta examensarbete är att konstruera en DC/DC-omvandlare som uppfyller de krav som utarbetats i samarbete med CrossControl. För att uppnå tillräckligt hög effektivitet, samt för att galvanisk isolation mellan in- och utgångsspänning är ett krav, baseras omvandlaren på en såkallad switchad flyback-lösning. Transformatorn är den enskilda komponent som har störst betydelse för funktionen hos en flybackomvandlare. Därför har en stor del av projektet handlat om att välja en passande transformator. Resultatet är en prototyp som klarar att reglera utspänningen till 24VDC för hela inspänningsområdet, och klarar en belastning på 50W. Effektiviteten slutade på 80% vilket är 5 procentenheter under målet. För att förbättra prototypen behövs dels övervakning och dels skydd mot att inspänningen går utanför det tänkta inspänningsområdet. För att uppnå 85% effekCross Control is a company that produces embedded computer solutions. A computer’ s normal input voltage is 18-30 VDC and consumes at the most 50W. The computers are sold to several different customers, who use them in anything from forwarders to trains. In separate vehicles the supply dc current varies from one vehicle to another. This creates needs to convert the voltage to a level that the computers can handle. Such a device is called a DC/DC-converter. Voltage conversion can be performed in different ways, either through linear regulation, or by using switching technology. The goal of our work is to design a DC/DC-converter that meets the requirements raised in cooperation with CrossControl. To achieve sufficient efficiency, and since galvanic isolation between input and output voltage is a requirement, the converter is based on a switched flyback solution. The transformer is the most important component for the converter function. Therefore, a large part of the project was focused on selecting a suitable one. The result is a prototype that is capable of regulating the output voltage to 24VDC for the entire input range, and can handle a load of 50W. The effectiveness ended at 80% which is 5% below target. To improve the prototype it is necessary to protect it from voltage outside input range. To achieve 85% efficiency one could redesign the snubber network.
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Zhang, Jianxi. "LCL DC/DC converter and DC hub under DC faults and development of DC grids with protection system using DC hub." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231428.
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In this thesis, an IGBT-based DC/DC converter employing an internal inductor-capacitor-inductor (LCL) passive circuit is investigated in DC grid under fault conditions. It is concluded that a range of converter parameters exist which will give DC fault current magnitudes close to rated currents. Steady state and transient fault responses are investigated in depth. The converter is modelled on PSCAD platform under fault operation and the simulation results verify the analytical studies. LCL DC hub is an extension of DC/DC converter to multiple ports with capability of limiting the propagation of DC faults in a DC grid. Analytical mathematical equations for steady state fault currents are derived. A state space model of the hub is introduced for transient fault study. The hub is able to interconnect multiple DC cables at different voltage levels and act as DC substation for DC grid. The designed hub also has the ability to maintain the current within the order of its rated value without additional protection even for the worst case fault. The analytical study results are confirmed by detailed simulation on PSCAD. Based on the good performance of the LCL DC hub under DC faults, a DC grid topology with protection system employing LCL DC hub is proposed and investigated in this thesis. The advantage and feasibility of this method in DC fault protection is investigated based on the developed grid model. The DC grid protection systems are proposed and analysed in depth under several DC fault scenarios. The PSCAD simulation results under a range of DC fault scenarios on various locations are shown. These results confirm significance of the proposed DC grid protection system and advantages of this proposed topology in fault isolation.
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Jia, Hongwei. "Highly Integrated DC-DC Converters." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3194.
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A monolithically integrated smart rectifier has been presented first in this work. The smart rectifier, which integrates a power MOSFET, gate driver and control circuitry, operates in a self-synchronized fashion based on its drain-source voltage, and does not need external control input. The analysis, simulation, and design considerations are described in detail. A 5V, 5-μm CMOS process was used to fabricate the prototype. Experimental results show that the proposed rectifier functions as expected in the design. Since no dead-time control needs to be used to switch the sync-FET and ctrl-FET, it is expected that the body diode losses can be reduced substantially, compared to the conventional synchronous rectifier. The proposed self-synchronized rectifier (SSR) can be operated at high frequencies and maintains high efficiency over a wide load range. As an example of the smart rectifier's application in isolated DC-DC converter, a synchronous flyback converter with SSR is analyzed, designed and tested. Experimental results show that the operating frequency could be as high as 4MHz and the efficiency could be improved by more than 10% compared to that when a hyper fast diode rectifier is used. Based on a new current-source gate driver scheme, an integrated gate driver for buck converter is also developed in this work by using a 0.35μm CMOS process with optional high voltage (50V) power MOSFET. The integrated gate driver consists both the current-source driver for high-side power MOSFET and low-power driver for low-side power iv MOSFET. Compared with the conventional gate driver circuit, the current-source gate driver can recovery some gate charging energy and reduce switching loss. So the current-source driver (CSD) can be used to improve the efficiency performance in high frequency power converters. This work also presents a new implementation of a power supply in package (PSiP) 5MHz buck converter, which is different from all the prior-of-art PSiP solutions by using a high-Q bondwire inductor. The high-Q bondwire inductor can be manufactured by applying ferrite epoxy to the common bondwire during standard IC packaging process, so the new implementation of PSiP is expected to be a cost-effective way of power supply integration.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD
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Warren, James Raymond III. "Cell modulated DC/DC converter." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/37061.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 97-99).
A very high frequency converter roughly based on a class E topology is investigated for replacing a conventional boost converter circuit. The loss mechanisms in class E inverters are characterized, and metrics are developed to aid in device selection for high frequency converter. A (30 MHz) converter is developed based on a modified class E inverter, single diode rectifier, and cell modulation control architecture based on the Fairchild Semiconductor FDN361AN MOSFET identified by the device selection metrics. In addition to meeting the output specification of 1 W to 2 W, the converter has the ability to deliver up to 3W over its entire input voltage range of 3.6V to 7.2V. Converter efficiencies were realized ranging from from 71% to 81%. Finally, converter transient response to a 2:1 load step did not even exceed the transient ripple of the converter, approximately 100mV. Higher frequency design allowed for decreasing the magnitude of passive values, and in turn their corresponding physical size. Smaller magnitude components reduced the energy storage in the circuit, allowing for the improved transient response.
(cont.) A potential application for this research include integration of the circuit and/or passive components for further miniaturization. Potential applications that could take advantage of the significantly improved transient response are circuits facing load transients, or applications designed to actively modulate their supply voltage or power.
by James Raymond Warren, III.
M.Eng.
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Chauhan, Shweta. "Hysteretic controlled DC-DC converters." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1418308376.
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Swaisi, Mahmoud. "DC distribution grid and the associated advanced DC/DC converter." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/43494/.
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AC or DC has been in the centre of debate since the early days of the electrical system. DC is already proven to be more economical than AC in transmission at elevated power and voltages. Thus, expanding the use of DC to the distribution grids seems promising as most of the distributed generation such as PV generates initial DC voltages and many of the modern loads are using internal DC buses. Still, in order to extend the use of DC to the distribution level a suitable DC distribution grid architecture and a suitable DC/DC converter to serve it should be explored, which is the focus of this Ph.D. A study based on the Libyan grid and loads was carried out to investigate the most suitable DC distribution grid layout. The results showed that DC grid arrangement utilising two port converters have lower total converter losses and smaller converter installed power when compared with arrangements using three ports converter. A multi-cell multi–snubbered three phase dual active bridge (DAB) converter was proposed to serve the chosen DC distribution grid layout. The modular multi-cell multi–snubbered 3 phase DAB converter offered low losses over a wide range of loading profiles. Furthermore, the converter performance can be easily modified to be able to serve a specific DC/DC grid loading profile by altering the snubbers attached to the cells and the power management’s algorithm between the cells while keeping the core cells the same. Extra cells can be added if higher power rating is required, reducing the total cost of expanding the proposed DC distribution system. This thesis is an ambition step on deciding the structure of the futuristic DC grid and the required DC/DC converters to link it is different voltage levels.
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Liu, Richard Sinclair. "Smart DC/DC Wall Plug Design For The DC House Project." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1802.
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The present day duplex wall receptacle in the United States provides 120Vrms AC at 60Hz, which comes from a standard set for AC loads by the National Electrical Manufacturers Association. With a DC system, such as what is used in the DC House project currently being developed at Cal Poly, providing DC power to DC loads presents a technical challenge due to the different required DC operating voltages of the loads. This thesis entails the design and construction of a Smart DC/DC Wall Plug, which can automatically adjust its output voltage to match any required DC load voltages. In the DC House implementation, renewable energy sources generate power to feed a 48V DC Bus. The Smart DC/DC Wall Plug converts power from the 48V bus to the appropriate voltage and power levels needed by the DC loads. The Smart DC/DC Wall Plug relies on load current detection, and uses a 10-bit digital potentiometer and a programmable current DAC to adjust the feedback network, thereby changing the output voltage. A dual channel 100W PCB prototype utilizing a STMF302R8 microcontroller is implemented for this design while confining to the NEMA wall outlet form factor. Results of hardware test verify the functionality of the Smart DC/DC Wall Plug in producing the required DC load voltages. Technical issues during the development of the Smart DC/DC Wall Plug will be described, along with suggestions to further improve from the current design.
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Baltierrez, Jason. "Multiple Input, Single Output DC-DC Conversion Stage for DC House." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2028.
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n this thesis project, a proposed architecture for the multiple input, single output conversion stage for the DC House was designed, simulated, and tested. This architecture allows for multiple different input sources to be used to create a single higher power output source. The design uses a DC-DC boost converter with a parallelable output which has been demonstrated to allow increased total output power as a function of the number of input sources available. The parallelable output has been shown to distribute load amongst the input sources relatively closely to optimize the system. This approach is also desirable since it allows for flexibility in multiple configurations it can be used in. The design was tested using hardware and data results show the performance met and exceeded the needs of the DC House project. Data was taken for configuration with 1, 2, 3, and 4 input sources providing greater than 600W of total output power at an efficiency of greater than 92%. This architecture demonstrates the possibility of expanding the total available power for a single output in proportion to the number of available input sources.
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Rivas, Juan 1976. "Radio frequency dc-dc power conversion." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38691.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2007.Includes bibliographical references (p. 197-204).
THIS THESIS addresses the development of system architectures and circuit topologies for dc-dc power conversion at very high frequencies. The systems architectures that are developed are structured to overcome limitations associated with conventional designs. In particular, the new architectures described here structure the energy processing and control functions of the system in such a manner that high efficiency can be achieved across wide load range while regulating the output. Moreover, these architectures are amenable to circuit designs operating at fixed frequency and duty ratio, considerable easing the circuit design. The thesis also develops new circuit designs that are well suited to these new architectures. As part of this, two new gate drives and control methods are introduced that greatly reduce gating loss at VHF frequencies for fixed frequency, fixed duty ratio operation. One of these gating schemes provides near theoretical minimum loss by resonantly wave shaping the gate voltage to have a trapezoidal drive voltage. This waveshaping approach is then taken a step further, yielding a new class of dc-dc converter that archives a significant reduction in peak switch voltage stress, requires small passive components with low energy storage, and provides the capability for extremely rapid startup and shutdown. This new class of converter is well adapted to the architectures and gate drive methods proposed in the thesis. It is expected that the new architectures and circuit designs introduced here will contribute to the development of power converter having greatly reduced size and improved transient performance.
by Juan Rivas.
Sc.D.
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Eliáš, Marek. "DC/DC měnič pro záložní zdroje." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-402133.
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This thesis deals with the design of a DC/DC converter designed for charging supercapacitors from the 36 V voltage source and consequent back transformation of supercapacitors voltage to the required output voltage. In the thesis the designs of decreasing and increasing DC/DC converters including schematics and calculations of individual components are presented and described. The calculations necessary for the supercapacitors to meet the 10Wh energy condition and the voltage balancer on the capacitors are given below. Completely designed equipment will be assembled and tested on supercapacitors with lower energy.
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Chadha, Ankit. "Tapped-Inductor Buck DC-DC Converter." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1578488939749599.
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Khopkar, Rahul Vijaykumar. "DC-DC converter current source fed naturally commutated brushless DC motor drive." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1257.
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The aim of this work is to reduce the cost and size of a brushless dc motor (BLDC) drive as well as increase the reliability and ruggedness of that drive. Traditional BLDC drives use Voltage Source Inverters (VSI) that utilize hard switching, thereby generating switching losses and entail the use of large heatsinks. VSI needs a huge dc link capacitor that is inherently unreliable and is one of the most expensive components of a drive. Hence, a Current Source Inverter (CSI) is used to replace the hard switchings by natural turn-off, thereby eliminating the heatsinks as well as the large dc link capacitor. A controlled rectifier together with a large inductor act as the current source. The only disadvantage is the large value of the dc link inductor and the huge number of turns needed to achieve these values of the inductances lead to huge resistive losses.
Therefore, it is shown that it is possible to replace the controlled rectifier and the large inductor with a suitable dc-dc converter based current source switching at high frequencies and a much smaller value of the dc link inductor. Switching at high frequencies makes it possible to reduce the value of the dc link inductor without increasing the current ripple. Hence, it is possible to have the advantages of using a CSI as well as reduce the value of the dc link inductor without a corresponding increase in the heat sink and snubber requirements.
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Badawy, Ahmed Darwish. "Current source dc-dc and dc-ac converters with continuous energy flow." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25915.
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This work considers current sourced powerelectronic converters. The thesis classifies and presents several new single-phase and three-phase differential-mode current source inverters that evolve from the basic dc-dc converter topologies. The switched, large-signal, and small-signal models of these converters are presented, and used to develop control strategies for the proposed differential-mode inverters, considering their inversion and rectification modes. The viability of each differential mode inverter/rectifier is validated using simulations and experimentation. The performances of different proposed buck, boost, and buck-boost current source inverters are discussed and compared in terms of efficiency, total harmonic distortion, input current ripple, capacitor stresses, and control complexity. Some of the proposed current source inverters offer buck-boost capability (can operate with output voltage less or greater than the input dc voltage), which is suited for grid-connected operation of single-stage three-phase buck-boost inverters. Phase variables and synchronous frame controllers are used to provide satisfactory inverter operation in inversion and rectification modes. The inherent low-order harmonic currents in the input and output of the proposed converters (predominantly, negative sequence 2nd order harmonic) are supressed using PI and PR controllers. Also, interleaved carriers are used to reduce the input current ripple of the three-phase inverters. The proposed converters can operate over a full control range from 0 to unity power factor, with power flow in both directions (unlike the conventional six-pulse current inverter). Additionally, a nonlinear control strategy, sliding mode control, is implemented with to achieve faster dynamic inverter response during faults as well as elimination of dccurrent injection into ac grid. This is necessary during unbalanced operation. Operation of single-phase differential-mode buck-boost inverters is presented, including suppression of the 2nd order harmonic in the input dc current by two methods. In the first, active suppression of the 2nd harmonic uses a power electronic circuit. The second method manipulates the modulating signal in combination with a relatively large capacitor to trap the oscillating power that causes the 2nd order harmonic to appear input dc link current. The two single-phase harmonic suppression approaches are compared.
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Patil, Sandeep. "Analysis and Loss Estimation of Different Multilevel DC-DC Converter Modulesand Different Proposed Multilevel DC-DC Converter Systems." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1396628125.
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Pekuz, Cagdas. "Z-source, Full Bridge Dc/dc Converter." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612775/index.pdf.
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The thesis is related to investigate characteristics and performance of a Z-source full
bridge dc/dc converter which boosts the input voltage to a higher output voltage. Zsource
structure increases the reliability of the converter according to current fed full
bridge dc/dc converter and also reducing the complexity according to two stage
design approach (boost followed by full bridge). Operating principles of the Z-source
dc-dc converter is described by current and voltage waveforms of the components
and mathematical expressions. Moreover, small signal models and transfer
functions are derived for both continuous current mode (CCM) and discontinuous
current mode (DCM) operations of the converter. Waveforms obtained,
mathematical expressions, small signal models and transfer functions derived are
confirmed by simulations. Performance of the converter and controller are both
tested in laboratory prototype.
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Nisar, Kashif. "DC to DC converter for smart dust." Thesis, Linköpings universitet, Institutionen för systemteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77247.
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This work describes the implementation of DC to DC converter for Smart Dust in 65 nm CMOS technology. The purpose of a DC to DC converter is to convert a battery voltage of 1 Vto a lower voltage of 0.5 V used by the processor. The topology used in this DC to DC converteris of Buck type which converts a higher voltage to lower voltage with the advantage of givinghigh efficiency about 75%. The system uses PWM (Pulse width modulation) technique. It usesnon-overlapping clock generation technique for reducing the power consumption. The systemprovides up to 5 mA load current and has power consumption of 2.5 mW.
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Torrico, Medrano Harold, and Bazaes Aristides Granado. "DC/DC-omvandlare för drivning av lysdiodmatris." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177154.
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Syftet med detta examensarbete var att designa en DC/DC-omvandlare så att den kan driva en 200 W LED-panel med hög effektförbrukning. Arbetet har utförs på uppdrag av INDUSEC AB, ett företag i skerhetsbranschen. DC/DC-omvandlaren kommer att utgöra en del av en produkt i företagets sortiment som de planerar att sälja på den internationella marknaden. Arbetet har realiserats på företaget samt vid Kungliga Tekniska Högskolan i Stockholm. Uppsatsen är en dokumentation över processen och resultatet av arbetet med att designa DC/DC-omvandlaren. I syfte att ge läsaren en djupare förståelse för innehållet i denna text inleds uppsatsen med en teoretisk förklaring till några grundläggande principer för DC/DC-omvandlare följt av teori kring de komponenter som används i arbetet. Dokumentet innehåller två viktiga delar som utgör huvuddelen av arbetet; beräkningen av värdena för komponenterna samt kretsarnas simulering. Resultatet av de gjorda simuleringarna analyseras och utifrån det designas kretsen. Beräkningen av värdena för komponenterna samt kretsarnas simulering jämförs och diskuteras för att få en bättre förståelse för problematiken kring att designa en slutlig krets som uppfyller de ställda kraven. Uppsatsen avslutas med en slutsats och förslag för det fortsatta arbetet.This report has the main purpose to design and dimensioning a part of a product to be finished, the product will be built by INDUSEC AB with plans to be sold in the international market. The part that we are going to design is a DC/DC converter that powers a Led array platform with high power consumption. The work is performed at the company facilities and at the Royal Institute of Technology in Stockholm. The document is started with a theoretical explanation of some fundamentals about basic DC/DC converters followed by a bit of theory about some components in order to provide a deeper understanding to the reader of this text. The report includes two important parts that are fundamental to the project; the calculation of the values of the components and the circuit simulation. The circuit design will be based on simulation results. The results from both parts are compared and discussed to get a better understanding about the difference between the calculated values and the final circuit. We summarized the document with a conclusion and some suggestions for further work.
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Appel, Daniel. "Optimalizácia návrhu spínaného regulovateľného DC-DC konvertora." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242181.
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The main goal of this project was an optimization of DC-DC converter design from company Meatest with regards to its efficiency, minimalizing power loses and radiated electromagnetic inference, while maintaining its price on reasonable level. The first part of this paper is introduction to the most common converter topologies. In the second part, design and optimization of converter are discussed. The third part is about measurement automatization in Simple. Measurements of converter prototype can be found in fourth part.
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Yeow, Eddie Y. "Design of high-density dc/dc converters." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/41524.
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Zero- Voltage-Switching Multi-Resonant-Converter (ZVS-MRC) techniques are applied with hybrid microelectronics fabrication technologies to design and implement efficient, high-density (>50 W/in³) dc/dc converters.
A low-profile high-density power stage of a 25 W dc/dc flyback ZVS-MRC is designed and built, and experimental results are shown. A high-density control circuit for a 50 W forward ZVS-MRC is designed using an integrated controller. This circuit is implemented into the high-density power stage previously designed by Tabisz and Lee to attain an overall converter power density of above 80 W/in³. A low-profile interleaved winding structure, fabricated by laminating copper-on-polyamide, for the transformer in the 50 W ZVS-MRC is introduced. Finite element analysis is performed to show the advantages gained with this structure.Master of Science
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Rezaee, Ali. "WIDE RANGE BI-DIRECTIONAL DC-DC CONVERTER." Thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-41189.
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Bi-directional DC-DC converters are used for applications that require a flow of energy in two directions, while a wide range converter offer efficient operation over a wide range of input and output voltages. However, an efficient technology that is both bi-directional and Wide Input Wide Output (WIWO), currently, does not currently exist. To find a suitable topology, the work began by surveying the existing literature and when a potentially suitable solution was identified, it was evaluated via simulation. Using a wide range, unidirectional topology as the starting point, a converter topology was designed, capable of reconfiguring its transformer ratios by controlling the synchronization of its switches. By aiming to use soft switching in simulation, this topology was improved to reach 92\% efficiency in the forward mode and 95\% in the reverse mode of operation. Furthermore, a prototype of this converter was developed that reached 82\% efficiency. While this prototype requires a better controller, hardware optimization and testing for optimal performance, the proposed technology was verified via simulation to work as a WIWO converter that is also bi-directional.
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Holub, Miroslav. "DC-DC měnič pro palubní dobíjení elektromobilu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-401968.
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This master thesis deals with design of DC-DC converter for onboard charging of electric vehicle. Developed converter will mainly be used for charging stationary traction battery in laboratory. Output voltage of this charger will be adjustable by user in between 200 V and 450 V depending on the current charged battery configuration. Output current limit is set at 8 A. Since the converter will be supplied from standard household socket, the problem of power factor correction must be solved during the design. That is because a large part of this thesis is focused on describing the problematics of power factor correction. After that, active PFC module is designed, completed and performance of this module is verified. To achieve low overall losses and thus be able to keep small volume of the system, modern switching components based on Silicon Carbide were preferred. Beside laboratory use, completed system will be used to emphasize volumetric difference between onboard chargers based on old versus modern switching components.
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Dvořák, Petr. "Dvojčinný kvazirezonanční DC/DC měnič s transformátorem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-412973.
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This diploma thesis deals with analysis of function and subsequent construction of a quasi-resonant DC / DC converter 300 V / 50 V for an output of about 1.5 kW. The aim of this work is to test and describe the behavior of an experimental converter at various operating parameters. In the theoretical part, resonant circuits are described, as well as our connection of the resonant converter. Based on the used topology and the simulated behavior of the converter, the individual components of the power circuit and its control and excitation circuit are designed in Chapters 4 and 5. The sixth chapter deals with the construction and testing of the converter, including a description of its behavior. The last chapter contains technical documentation.
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Sikora, Roman. "DC-DC měnič pro matrix beam modul." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413161.
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The master thesis deals with the development of buck-boost DC-DC converter which supplies matrix beam module. The design is focused on testing two-phase boost converter and three channel buck converter manufactured by NXP Semiconductors. Part of the design is implementation of microcontroller for converter control and communication with computer. Part of the thesis is also to design user interface on Windows platform for easy system configuration. Next thing the thesis deals with is designing load for DC-DC converter that is variable and can make different current consumption. One part of this thesis is focused to achieve the lowest conducted emissions and to maximize conducted immunity. Part of this project is production of a prototype and prototype testing.
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Prasantanakorn, Chanwit. "Current Sharing Method for DC-DC Transformers." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/31112.
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An ever present trend in the power conversion industry is to get higher performance at a lower cost. In a computer server system, the front-end converter, supplying the load subsystems, is typically a multiple output power supply. The power supply unit is custom designed and its output voltages are fully regulated, so it is not very efficient or cost effective. Most of the load systems in this application are supplied by point-of-load converters (POLs). By leaving the output voltage regulation aspect to POLs, the front-end converter does not need to be a fully regulated, multiple output converter. It can be replaced by a dc-dc transformer (DCX), which is a semi-regulated or unregulated, single output dc-dc converter. A DCX can be made using a modular design to simplify expansion of the system capacity. To realize this concept, the DCX block must have a current sharing feature.
The current sharing method for a resonant DCX is discussed in this work. To simplify the system architecture, the current sharing method is based on the droop method, which requires no communication between paralleled units. With this method, the current sharing error is inversely proportional to the droop voltage. In traditional DCX implementations, the droop voltage depends on the resistive voltage drops in the power stage, which is not sufficient to achieve the desired current sharing error. The resonant converter has the inherent characteristic that its conversion gain depends on the load current, so the virtual droop resistance can realized by the resonant tank and the droop voltage can be obtained without incurring conduction loss. An LLC resonant converter is investigated for its droop characteristic. The study shows the required droop voltage is achievable at very high switching frequency. To lower the switching frequency, a notch filter is introduced into the LLC resonant tank to increase the sensitivity of the conversion gain versus the operating frequency. The design of the multi-element resonant tank is discussed. Depending soly on the resonant tank, the droop characteristic is largely varied with the component tolerance in the resonant tank. The current sharing error becomes unacceptable. The active droop control is imposed to make the output regulation characteristic insensitive to the component tolerance. The proposed resonant DCX has simpler circuit structure than the fully regulated resonant converter. Finally simulation and experimental results are presented to verify this concept.Master of Science
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Al, Kzair Christian. "SiC MOSFET function in DC-DC converter." Thesis, Uppsala universitet, Elektricitetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415147.
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This thesis evaluate the state of art ROHM SCT3080KR silicon carbide mosfet in a synchronous buck converter. The converter was using the ROHM P02SCT3040KR-EVK-001 evaluation board for driving the mosfets in a half bridge configuration. Evaluation of efficiency, waveforms, temperature and a theoretical comparison between a silicon mosfet (STW12N120K5) is done. For the efficiency test the converter operate at 200 V input voltage and 100 V output voltage at output currents of 7 A to 12 A, this operation was tested at switching frequencies of 50 kHz, 80 kHz and 100 kHz. The result of the efficiency test showed an efficiency of 98-97 % for 50 kHz, 97.7-96.4 % for 80 kHz and 97-96.2 % for the 100 kHz test. The temperature test shows a small difference in comparison of the best case scenario and the worst case scenario, temperature ranges from 25.5 to 33.5 °C for the high side mosfet while the low side mosfet temperature ranges from 29.8 to 35 °C. The waveform test was conducted at 50 kHz and 100 kHz for output currents of 4 A and 12 A (at 200 V input and 100 V output). The result of the waveform test shows a rise and fall time of the voltages in range of 10-12 ns while the current rise and fall time was 16 ns for the 4 A test and 20 ns for the 12 A test. Overall SiC mosfet show a clear advantage over silicon mosfet in terms of efficiency and high power capabilities.
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Chudý, Andrej. "DC/DC měniče pro průmyslové napájecí zdroje." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442795.
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This diploma thesis deals with design and comparison of selected DC/DC converters, where the better of them is practically realized. The first part of the diploma thesis is focused on the general analysis of DC/DC power converters. The following part is theoretical analysis focused on the first selected topology – step-up converter. The second analysed topology is forward converter with full bridge on the primary side. The theoretical analysis also includes a description of synchronous rectifier, the differences between hard and soft switching, and the types of secondary rectifiers. Another part specializes in the detailed calculation of main components of selected converters and their subsequent power dimensioning. Both designed topologies are compared according to the required aspects. The selected better topology is supplemented by the design of control circuits and an auxiliary power supply. Practical realization of converter and commissioning follows. The diploma thesis ends with verification measurements on the realized converter and their subsequent analysis.
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Zengel, Jason A. "DC-DC power conversion with galvanic isolation." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FZengel.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2003.Thesis advisor(s): Robert W. Ashton, Todd R. Weatherford. Includes bibliographical references (p. 83-84). Also available online.
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DI, LORENZO ROBERTO. "DC-DC Buck Converter For Automotive Applications." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/301996.
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L'avvento del MOSFET di potenza è uno degli sviluppi più significativi nell'elettronica di potenza negli ultimi anni. Mentre i dispositivi verticali apparsi alla fine degli anni settanta sembravano destinati a trovare un posto importante nel mercato, in particolare nell'area della conversione di potenza ad alta frequenza, il predominio generale del transistor bipolare di potenza non sembrava seriamente minacciato. Tuttavia, quando i dispositivi DMOS verticali più facilmente fabbricabili apparvero in volume nel 1978, la scena era pronta per una rivoluzione. Il MOSFET di potenza ha rapidamente raggiunto la reputazione di essere tollerante e facile da progettare, ma l'accettazione universale è stata ritardata dal suo costo relativamente alto.
L'elettronica automobilistica che funziona dalla batteria dell'auto subisce tensioni transitorie come l'avviamento a freddo e lo scarico del carico che possono variare da 4,5 V a> 30 V. Inoltre, le nuove tecnologie come start-stop aumentano la frequenza di tali transitori e i requisiti operativi dei dispositivi elettronici. Ciò richiede circuiti integrati di alimentazione o batteria per resistere a condizioni operative difficili e fornire alimentazione affidabile all'intero veicolo. Ad esempio, l'aria condizionata, le luci anteriori / posteriori dell'auto dovrebbero mantenere la loro funzionalità durante le condizioni di avviamento indotte da start-stop. Questo requisito può essere soddisfatto in modo efficiente e affidabile dai convertitori DC-DC.
L'industria automobilistica sta rapidamente passando dalle lampade a filamento ai nuovi sistemi (LED) per l'illuminazione anteriore / posteriore in quanto offrono prestazioni migliori in termini di efficienza energetica rispetto a quelli convenzionali. Tuttavia, a causa delle caratteristiche elettriche di questi sistemi presenti in un'auto non può essere alimentato direttamente dalla batteria dell'auto. Richiedono circuiti di pilotaggio specializzati in grado di rispondere alle mutevoli esigenze dei carichi al variare delle loro proprietà elettriche mantenendo la corrente uniforme. I convertitori DC-DC sono il modo più semplice per alimentare tale carico con una corrente costante. Di conseguenza, i convertitori Buck, Boost e Buck-Boost DC-DC per applicazioni automobilistiche sono di grande interesse per l'industria automobilistica. In particolare, non affrontato
finora sono soluzioni monolitiche nelle tecnologie Smart Power. Le tecnologie Smart Power consentono di integrare transistor di potenza, logica di controllo e diagnostica su un unico chip (SOC - System On Chip). Poiché i requisiti di resa elevata implicano solo fasi di lavorazione altamente mature e con esperienza. A causa dei requisiti di basso costo, viene utilizzata una sequenza di maschere ridotta, che porta normalmente a due livelli di interconnessione (polisilicio e metallo). In questa tesi è stato progettato un convertitore DC-DC per applicazioni automotive. Il primo capitolo di questo documento ha lo scopo di servire da introduzione al lettore per tutte le descrizioni del lavoro insieme al rapporto. Abbiamo bisogno di una tecnologia ad alta tensione per progettare un convertitore DC-DC integrato. Qui, userò la tecnologia smart power, questa tecnologia permette di creare interruttori di potenza high side con bassa resistenza.The advent of the power MOSFET ranks as one of the most significant developments in power electronics in recent years. While the vertical devices which appeared in the late seventies looked set to find an important place in the market, particularly in the area of high-frequency power conversion, the overall dominance of the power bipolar transistor did not seem seriously threatened. However, when the more easily manufacturable vertical DMOS devices appeared in volume in 1978, the scene was set for a revolution. The power MOSFET rapidly achieved a reputation for being forgiving and easy to design with, but universal acceptance was delayed by its relatively high cost. The automotive electronics operating from car battery experiences transient voltages such as cold-cranking and load dump which can range from 4.5V to >30V. In addition, the new technologies such as start-stop, increase the frequency of such transients and operational requirements of electronic devices. This requires o-battery power ICs to withstand harsh operating conditions and reliably provide power to the whole vehicle. As an example, the air condition, front/back car lights are supposed to keep their functionality during start-stop induced cranking conditions. This requirement can be efficiently and reliably fulfilled from DC-DC converters. The automotive industry is rapidly switching from filament lamps to new systems (LED) for front/back lighting as they perform better in terms of energy efficiency than the conventional ones. However, due to the electrical characteristics of these systems present in a car cannot be powered directly from the automotive battery. They require specialized driving circuits which can respond to the changing needs of the loads as their electrical properties change while maintaining the uniform current. DC-DC converters other the easiest way to power such the load with a constant current. As result Buck, Boost, Buck-Boost DC-DC converters for automotive applications are of great interest for the automotive industry. In particular, not addressed so far are monolithic solutions in Smart Power technologies. Smart Power technologies allow integrating power transistor, control logic and diagnostic on a single chip (SOC – System On Chip). Because high yield requirements they involve only highly mature, well-experienced processing steps. Because of low-cost requirements, a reduced mask sequence is used, leading normally to two interconnecting levels (polysilicon and metal). In this thesis, it has been designed a DC-DC converter for automotive applications. The first chapter of this document is aimed to serve as an introduction to the reader for all the work descriptions along with the report. We need a high voltage technology to design an integrated DC-DC converter. Here, I will use smart power technology, this technology permits to create high side power switch with low resistance.
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Veilleux, Etienne. "DC power flow controller and Marx DC-DC converter for multiterminal HVDC system." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116919.
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This thesis presents the concept of the dc power flow controller to address the power flow control issues inside a multiterminal High Voltage Direct Current (HVDC) system. The controller is connected in series on the HVDC transmission line and it is presented as a small appendage of a voltage source converter (VSC) station. The operation and the stability are shown via simulations of a 3-terminal and a 7-terminal HVDC grid. The controller increases the flexibility and the region of operation of the multiterminal HVDC system.The integration of an offshore wind farm into a multiterminal HVDC system is also studied. By using a dc collector network for the aggregation of power produced by the wind turbines, the high civil engineering cost of an offshore platform to support heavy ac transformers required by the converter station for HVDC transmission can be avoided. The challenge is to bridge the two dc voltages without ac transformers.This thesis introduces and analyzes a new dc-dc converter topology which is based on the Marx generator concept. The concept consists of charging capacitors in parallel followed by reconnection in series of the capacitors to create higher dc voltage. The converter with a multi-stage configuration is simulated for proof of concept. Design guidelines are developed and a 5kW prototype has been constructed to verify experimentally the converter topology. The stability of the converter is analyzed using a sampled-data approach and the power ratings of the semiconductor switches and passive components are evaluated.For offshore wind farm application, the Marx dc-dc converter is combined with a step-up converter to form the Marx offshore station which bridges the 10kV dc collector network to the 250kV HVDC transmission line. The Marx offshore station is simulated with an offshore wind farm and an onshore VSC inverter station.The two parts of the thesis, the dc power flow controller and the Marx dc-dc converter, are integrated within a complete multiterminal HVDC system. The simulated system comprises six VSC terminal stations, the Marx offshore station with an offshore wind farm and the dc power flow controller. Both the dc power flow controller and the Marx dc-dc converter enlarge the scope of multiterminal HVDC system.Cette thèse présente le concept d'un contrôleur de transit de puissance afin de résoudre la problématique de contrôle des mouvements d'énergie dans un réseau multiterminal à courant continu à haute tension (CCHT). Le contrôleur est installé en série sur la ligne de transport CCHT et il est présenté comme un module ajouté à une station convertisseur à CCHT. Le fonctionnement et la stabilité sont démontrés à l'aide de simulations dans des systèmes multiterminaux de 3 et de 7 terminaux. Le contrôleur augmente la flexibilité et l'étendue de l'exploitation d'un système multiterminal CCHT.L'intégration d'un parc éolien installé en mer avec un système multiterminal CCHT est aussi étudiée. En utilisant un réseau à courant continu (cc) pour collecter la puissance produite par les éoliennes, les coûts d'infrastructure associés au support de lourds transformateurs à courant alternatif (ca) requis pour la station du convertisseur servant au transport CCHT peuvent être évités. Le défi consiste à relier les deux tensions cc en omettant l'utilisation de transformateurs ca.Cette thèse introduit et analyse une nouvelle topologie de convertisseurs cc-cc qui est basée sur le concept du générateur Marx. Ce concept consiste à charger des condensateurs en parallèle pour ensuite les connecter en série afin de créer une tension cc plus élevée. Un convertisseur avec une configuration multi-étapes est simulé pour une démonstration de faisabilité. À partir de balises de conceptions, un prototype de 5kW a été conçu, simulé et construit afin de vérifier expérimentalement la topologie du convertisseur. La stabilité de la topologie a été analysée en utilisant une approche de données échantillonnées et des caractéristiques nominales des semiconducteurs de puissance et des composants passifs sont évaluées.Pour l'application dans un parc éolien installé en mer, le convertisseur cc-cc Marx est jumelé avec un hacheur survolteur afin de former une station Marx qui lie le réseau collecteur cc de 10kV au réseau de transport CCHT de 250kV. La station Marx est simulée avec un parc éolien et un convertisseur onduleur.Les deux parties de cette thèse, soit le contrôleur de transit de puissance et le convertisseur cc-cc Marx, sont regroupés dans un même système multiterminal CCHT. Le réseau simulé comprend six stations convertisseurs de type « voltage source converter », la station Marx avec le parc éolien installé en mer et le contrôleur de transit de puissance. Le contrôleur de transit de puissance et le convertisseur cc-cc élargissent la portée du système multiterminal CCHT.
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Ahmed, Oday Ali. "Investigation into high efficiency DC-DC converter topologies for a DC microgrid system." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10165.
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Distributed generation in the form of DC microgrids has recently attracted increasing research interest. For integrating primary sources and energy storage devices to the DC bus of a DC microgrid power electronic converters are necessary, but the associated losses may degrade the microgrid efficiency. Therefore, the aim of this work is to develop high-efficiency converters, particularly for fuel cell generators and ultracapacitors energy buffers suitable for use in a stationary distribution system. Based on the evaluation of the fuel cell dynamic performance, a current–fed DC–DC converter design with a lower voltage rating of the switching devices and a higher DC voltage conversion ratio is proposed. A number of optimisation approaches have been applied to further improve the converter efficiency over its full power range. The periodic steady state operation of the converter is analysed in detail; state-space averaging is then used to determine the small signal equations and derive transfer functions. A closed loop controller has been designed and verified by a novel PSpice/Simulink/actual processor co–simulation approach, where the modelling results are validated by experimental results using a model–based design method. To sustain the charging and discharging states of the ultracapacitor, a bidirectional DC–DC converter is required. Based on a comprehensive overview on different DC–DC converter topologies, the research presented here has shown that, bidirectional voltage–fed topology is better suited for dealing with the fast dynamic response of the ultracapacitor. But for a wide input voltage variation, this topology exhibits a higher circulating power flow and higher conduction losses as a consequence. Therefore, a detailed analysis of the bidirectional converter exploring the impact of the circulating power flow interval is developed in this study. Analytic methods have been applied to establish the optimal operation of the bidirectional voltage–fed converter for an ultracapacitor to improve its performance and efficiency. Based on these methods, a novel modulation scheme is proposed that minimises the circulating power flow in the converter, that has been verified by detailed simulation.
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Fan, Shixiong. "Current source DC/DC converter based multi-terminal DC wind energy conversion system." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=17007.
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Wind power energy conversion is growing rapidly in the world. There are two main wind farm types, namely ac grid-based and dc grid-based wind farms. The dc grid-based approach reduces the size and weight of the magnetic components and cables. In the dc system, the step-up dc/dc converter is the key component when interfacing the wind turbine to the ac grid, via its low/medium voltage generator. This thesis focuses on the control and design of a wind energy conversion system based on dc/dc current source converters. An optimized One-Power-Point method for maximum power tracking is proposed. It incorporates One-Power-Point control and Maximum Power Differential Voltage control to allow the wind turbine to extract more energy during rapid wind speed changes. A current output hard-switched full bridge converter and serial-parallel resonant converter with an intermediate high frequency transformer are investigated for interfacing wind turbines to a local dc grid. These converters are assessed and compared in terms of semiconductor stresses and losses. A new modified One-Power-Point control method is proposed for the dc/dc converter, which tracks the maximum power during wind speed changes. A design procedure for the serial-parallel resonant converter is presented, based on its characteristics specific to a wind energy conversion system (WECS). A current source dc/dc converter based multi-terminal dc WECS is presented, investigated, and simulated. A practical multi-terminal dc WECS verifies its feasibility and stability, using two dc current output wind turbine units. Furthermore, a coordinated de-loading control scheme for the current sourcing based WECS is proposed, to cater for ac grid demand changes. It combines pitch control, dc dumping chopper control, and dc/dc converter control, to safely and quickly establish de-loading control. Both simulation and experimental results verify the de-loading scheme.
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Wong, Chi Kin Taffy. "A MULTIPLE-INPUT SINGLE-OUTPUT DC-DC CONVERTER FOR THE DC HOUSE PROJECT." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/632.
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This thesis entails the design of a multiple-input single-output (MISO) dc-dc converter. The converter will be used to interface multiple power sources such as those obtained from renewable energy sources to a dc house. Results from the theoretical calculation and experimental data are presented in the report which demonstrate the functionality and performance of the proposed converter.
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Hu, Jing [Verfasser]. "Bewertung von DC-DC-Topologien und Optimierung eines DC-DC-Leistungsmoduls für das 42-V-Kfz-Bordnetz / Jing Hu." Aachen : Shaker, 2004. http://d-nb.info/118160527X/34.
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Langlois, Thomas L. "The analysis of interconnected, high-power DC-DC converters for DC zonal electrical distribution." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA333405.
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Luan, Austin J. "Bi-Directional Flyback DC-DC Converter for Battery System of the DC House Project." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1012.
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The DC House project strongly relies on renewable energy sources to provide power to the house for various loads. However, when these sources are unable to provide power at a certain time, a back-up energy source from a battery must be readily available to fulfill the house’s power needs. This thesis proposes a bi-directional flyback power converter to allow a single-stage power path to charge the battery from and to discharge the battery to the DC House 48 V system bus. The design, simulation, and hardware prototype of the proposed flyback bi-directional converter will be conducted to demonstrate its feasibility. Results from a 35W prototype demonstrate the operation of the proposed converter for both charging and discharging purposes.
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Kluempers, Eric C. "PSpice computer model of a dc-dc converter /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426076.
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Ambusaidi, Khalid Abdulaziz Khalid. "Fault Tolerant Multilevel Step-Down DC/DC Converters." Thesis, University of Newcastle upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512146.
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Peng, Hao. "Digital current mode control of DC-DC converters." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3207767.
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Elbkosh, Abdulmajed Omar. "Nonlinear analysis and control of dc-dc converters." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.500937.
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It is well known that switching dc-dc converters show a wide range of nonlinear behaviours including bifurcation, sub-haraionics and chaos when they operate outside their design specifications. These nonlinear patterns force the converter to change its normal periodic behaviour to a random-like behaviour; a situation that must be avoided. In this thesis, the nonlinear dynamics of switching dc-dc converters are investigated. It is shown for the first time that the concept of the monodromy matrix (i.e. the state transition matrix for one switching cycle, including the state transition matrices during the switching slants) can be successfully applied to determine the stability of switching dc-dc power converters.
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Wang, Xiangcheng. "HIGH SLEW RATE HIGH-EFFICIENCY DC-DC CONVERTER." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3196.
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Active transient voltage compensator (ATVC) has been proposed to improve VR transient response at high slew rate load, which engages in transient periods operating in MHZ to inject high slew rate current in step up load and recovers energy in step down load. Main VR operates in low switching frequency mainly providing DC current. Parallel ATVC has largely reduced conduction and switching losses. Parallel ATVC also reduces the number of VR bulk capacitors. Combined linear and adaptive nonlinear control has been proposed to reduce delay times in the actual controller, which injects one nonlinear signal in transient periods and simplifies the linear controller design. Switching mode current compensator with nonlinear control in secondary side is proposed to eliminate the effect of opotocoupler, which reduces response times and simplifies the linear controller design in isolated DC-DC converters. A novel control method has been carried out in two-stage isolated DC-DC converter to simplify the control scheme and improve the transient response, allowing for high duty cycle operation and large step-down voltage ratio with high efficiency. A balancing winding network composed of small power rating components is used to mitigate the double pole-zero effect in complementary-controlled isolated DC-DC converter, which simplifies the linear control design and improves the transient response without delay time. A parallel post regulator (PPR) is proposed for wide range input isolated DC-DC converter with secondary side control, which provides small part of output power and most of them are handled by unregulated rectifier with high efficiency. PPR is easy to achieve ZVS in primary side both in wide range input and full load range due to 0.5 duty cycle. PPR has reduced conduction loss and reduced voltage rating in the secondary side due to high turn ratio transformer, resulting in up to 8 percent efficiency improvement in the prototype compared to conventional methods.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Nathan, Kumaran Saenthan. "A novel DC-DC converter for photovoltaic applications." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288881.
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Growing concerns about climate change have led to the world experiencing an unprecedented push towards renewable energy. Economic drivers and government policies mean that small, distributed forms of generation, like solar photovoltaics, will play a large role in our transition to a clean energy future. In this thesis, a novel DC-DC converter known as the Coupled Inductors Combined Cuk-SEPIC' (CI-CCS) converter is explored, which is particularly attractive for these photovoltaic applications. A topological modification is investigated which provides several benefits, including increased power density, efficiency, and operational advantages for solar energy conversion. The converter, which is based on the combination of the Cuk and SEPIC converters, provides a bipolar output (i.e. both positive and negative voltages). This converter also offers both step-up and step-down capabilities with a continuous input current, and uses only a single, ground-referenced switching device. A significant enhancement to this converter is proposed: magnetic coupling of the converter's three inductors. This can substantially reduce the CI-CCS converter's input current ripple - an important benefit for maximum power point tracking (MPPT) in photovoltaic applications. The effect of this coupling is examined theoretically, and optimisations are performed - both analytically and in simulations - to inform the design of a 4 kW prototype CI-CCS converter, switched at a high frequency (100 kHz) with a silicon carbide (SiC) MOSFET. Simulation and experimental results are then presented to demonstrate the CI-CCS converter's operation and highlight the benefits of coupling its inductors. An efficiency analysis is also undertaken and its sources of losses are quantified. The converter is subsequently integrated into a domestic photovoltaic system to provide a practical demonstration of its suitability for such applications. MPPT is integrated into the CI-CCS DC-DC converter, and a combined half bridge/T-type converter is developed and paired with the CI-CCS converter to form an entirely transformerless single-phase solar energy conversion system. The combination of the CI-CCS converter's bipolar DC output with the combined half bridge/T-type converter's bipolar DC input allows grounding at both the photovoltaic panels and the AC grid's neutral point. This eliminates high frequency common mode voltages from the PV array, which in turn prevents leakage currents. The entire system can be operated in grid-connected mode - where the objective is to maximise power extracted from the photovoltaic system, and is demonstrated in stand-alone mode - where the objective is to match solar generation with the load's power demands.
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Wahby, Riad Samir 1981. "Radio frequency rectifiers for DC-DC power conversion." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16690.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 75-78).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
A significant factor driving the development of power conversion technology is the need to increase performance while reducing size and improving efficiency. In addition, there is a desire to increase the level of integration of DC-DC converters in order to take advantage of the cost and other benefits of batch fabrication techniques. While advances in the power density and integration of DC-DC converters have been realized through development of better active device technologies, much room for improvement remains in the size and fabrication of passive components. To achieve these improvements, a substantial increase in operating frequency is needed, since intermediate energy storage requirements are inversely proportional to frequency. Unfortunately, traditional power conversion techniques are ill-suited to handle this dramatic escalation of switching frequency. New architectures have been proposed which promise to deliver radical performance improvements while potentially reaching microwave frequencies. These new architectures promise to enable substantial miniaturization of DC-DC converters and to permit much a higher degree of integration. The principal effort of this thesis is the development of design and characterization methods for rectifier topologies amenable to use in the new architectures. A computational design approach allowing fast and accurate circuit analysis and synthesis is developed and applied, along with traditional analysis, to two demonstrative rectifier topologies. In addition, the application of coupled magnetic structures for parasitic mitigation is considered. Experimental implementations are investigated to verify analytic and computational results.
by Riad Samir Wahby.
M.Eng.
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Xu, Aidong. "Microprocessor controlled novel 4-quadrant DC-DC converter." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/19477.
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The thesis describes a novel 4-quadrant DC-DC converter, supplied by a 28V DC voltage source, with an output voltage which may be continuously varied between +180V and -180V DC. A prototype 1.2kW DC-DC converter was designed and built, with emphasis given to the optimization of both the converter size and efficiency. This was achieved by means of a computer-based simulation study, which determined the optimal switching frequency and the size of the inductors and capacitors while maintaining a high unit efficiency. Mos-Gated Bimos switches, which feature the advantages of both mosfets and bipolar transistors, were developed to achieve high switching speed during high power operation. A digital-controlled DC servo system based on a 16-bit Intel 8086 microprocessor was designed, to provide both motor speed and position control. Speed and position detection circuits and the structure and the interfacing arrangement of the microprocessor system were designed and constructed. Several control algorithms were developed, including PID Control Algorithm and Current-Limit Control Algorithm. Based on open loop transfer function of the system, derived through mathematical modelling using the State-Space Averaging Method, the constants for the control algorithms were obtained to meet the dynamic performance specified for the system. Computer simulation was carried out to assist with the design of the converter and the control system. It is expected that drives into which the novel converter is incorporated will find many applications in situations where accurate positional control is required, particularly in battery-operated DC-servo system, such as satellite system, robots and some military vehicles.
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Khan, Faisal Habib. "Modular DC-DC Converters." 2007. http://trace.tennessee.edu/utk_graddiss/210.
Full textAbstract:
DC-DC converter is one of the mostly used power electronic circuits, and it has applications in various areas ranging from portable devices to aircraft power system. Various topologies of dc-dc converters are suitable for different applications. In high power applications such as the bi-directional dc-dc converter for dual bus system in new generation automobiles, several topologies can be considered as a potential candidate. Regardless of the topology used for this application, the reliability of the converter can be greatly enhanced by introducing redundancy of some degree into the system. Using redundancy, uninterrupted operation of the circuit may be ensured when a fault has occurred.
The redundancy feature can be obtained by paralleling multiple converters or using a single modular circuit that can achieve this attribute. Thus, a modular dc-dc converter with redundancy is expected to increase the reliability and reduce the system cost. Recently, the advancement in power electronics research has extended its applications in hybrid electric automobiles. Several key requirements of this application are reliable, robust, and high efficiency operation at low cost. In general, the efficiency and reliability of a power electronic circuit greatly depend on the kind of circuit topology used in any application. This is one of the biggest motivations for the researchers to invent new power electronic circuit topologies that will have significant impact in future automobile industry.
This dissertation reviews existing modularity in power electronic circuits, and presents a new modular capacitor clamped dc-dc converter design that has many potential uses in future automotive power system. This converter has multilevel operation, and it is capable of handling bi-directional power. Moreover, the modular nature of the converter can achieve redundancy in the system, and thereby, the reliability can be enhanced to a great extent. The circuit has a high operating efficiency (>95%), and it is possible to integrate multiple voltage sources and loads at the same time. Thus, the converter could be considered as a combination of a power electronic converter and a power management system.
In addition to the new dc-dc converter topology, a new pair of modular blocks defined as switching cells is presented in this dissertation. This pair of switching cells can be used to analyze many power electronic circuits, and some new designs can be formed using those switching cells in various combinations. Using these switching cells, many power electronic circuits can be made modular, and the modeling and analysis become easier.
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Pascoal, Fábio Miguel Ferreira. "Inductorless DC\DC converter." Master's thesis, 2016. https://repositorio-aberto.up.pt/handle/10216/85953.
Full textAbstract:
Using nano-scale integration to create a DC-DC up converter from 0.8V supply to a stable 1.2V voltage that use no external inductors and minimal external component, namely capacitors. A study of the different topologies/techniques is performed with the respective evaluation of their pros and cons. Based on these, a circuit architecture is proposed and developed with proper validation of the circuit performance parameters like: power, ageing, precision, reliability, area, etc...
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Pascoal, Fábio Miguel Ferreira. "Inductorless DC\DC converter." Dissertação, 2016. https://repositorio-aberto.up.pt/handle/10216/85953.
Full textAbstract:
Using nano-scale integration to create a DC-DC up converter from 0.8V supply to a stable 1.2V voltage that use no external inductors and minimal external component, namely capacitors. A study of the different topologies/techniques is performed with the respective evaluation of their pros and cons. Based on these, a circuit architecture is proposed and developed with proper validation of the circuit performance parameters like: power, ageing, precision, reliability, area, etc...
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Hu, Yi-Nung, and 胡以農. "Charge Pump for DC/DC and DC/AC Conversion." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/50276889042776388388.
Full textAbstract:
碩士國立臺灣大學
電子工程學研究所
93
Charge pump, also called switched-capacitor voltage converter, can pump the lower direct-current voltage source to the higher dc output voltage. It is widely used in some memory components like DRAM and FLASH EEPROMs. And it can provide output voltages of different levels at the same time, so it also be used in the graphic card that is more complex than before. In this thesis, a charge pump voltage converter with push-pull type structure is proposed. In addition to the conventional dc voltage, this charge pump with different kinds of output stage can also generate an ac output voltage that is multiple times of the supply voltage. The push-pull structure can also stabilize the dc output voltage signal in addition to the generating of the ac output voltage signal. Besides, the high-side switches of the circuit are driven by the use of cross-coupled method. There is no need to provide an extra driving signal for the high-side switches like the conventional charge pumps. Difficulty of design can be greatly reduced. During design and analysis stages, the HSPICE is used for the simulation and modification of the circuit. Finally we compared the discrete circuit experiments with the simulation results, and verified the correctness of the circuit application. And we proved that it can be used to generate an ac output voltage that is different from the conventional circuits.
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Wang, Sheng-Yuan, and 王聖淵. "System integration of AC-DC and DC-DC Converter." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9a3zhg.
Full textAbstract:
碩士崑山科技大學
電子工程研究所
107
As the trend of electric vehicles is becoming clearer, the charging system is also charged by AC to DC. The main purpose of this thesis is to develop and discuss the application of an AC-DC and DC-DC integration. Can be applied to charging systems or other related consumer electronics. DC-DC Converter developed a system with DC48V, switching frequency of 60kHz~65kHz and power of 60W in the form of Flyback. And with AC-DC system.