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Gebrehiwet, Gebregergis Abraham. "A three-phase AC/AC matrix converter system." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16324.
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Thesis (MScIng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The thesis discusses the analysis and design of a three-phase-to-three-phase direct AC-AC matrix converter. A background study of the various matrix converter topologies and their modulation strategies are presented. The associated PWM strategy of each matrix converter topology is investigated. In addition, a detailed explanation of the three safe commutation strategies is presented. The research focuses on the design and analysis of the direct AC-AC matrix converter topology. That includes the design of the main bi-directional power converter circuit, gate drive circuit, current direction detection circuit, voltage measurement circuit and protection circuitry. Moreover, it covers the development of the direct control algorithm based on the four-step safe current commutation- and the two-step voltage commutation strategy. A “PEC33” controller board is used to implement the developed control algorithm. Furthermore, simulation results of the direct and the indirect matrix converter topologies are presented. The results obtained from the experimental test performed on the direct AC-AC matrix converter topology are also presented. The conclusion drawn is discussed at the final stage of the report.
AFRIKAANSE OPSOMMING: Hierdie tesis bevat die analise en ontwerp van ‘n drie-fase na drie-fase direkte WS-WS matriksomsetter. ‘n Agtergrondstudie van verskeie ander matriksomsetter topologieë word aangebied. Die ge-assosieerde PWM beheerstrategie van elke matriksomsetter topologie is ondersoek. Hierby word ‘n gedetaileerde verduideliking van drie veilige kommutasie strategieë ingesluit. Die navorsing fokus op die ontwerp en analise van die direkte WS-WS matriksomsetter topologie. Dit sluit die volgende in: die ontwerp van die hoof bi-direksionele drywingsomsetterbaan; die hek aandryfbaan; die stroomrigting deteksiebaan; die spanningsmeetbaan en die beveiliging stroombane. Dit dek ook die ontwikkeling van die direkte beheeralgoritme wat gebasseer is op die vier-stap veilige stroomkommutasie- en die twee-stap spanningskommutasie strategie. ‘n “PEC33” beheerkaart is gebruik om hierdie beheeralgoritme te implementer. Simulasie resultate van beide die direkte sowel as die indirekte matriksomsetter topologieë word ingesluit. Die eksperimentele resultate wat met die direkte WS-WS matriksomsetter topologie verkry is word aangebied en bespreek. Die gevolgtrekking word in die finale afdeling van die verslag bespreek.
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Chewele, Youngie Klyv. "Model predictive control of AC-to-AC converter voltage regulator." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86339.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The development of fast and efficient processors, programmable devices and high power semiconductors has led to the increased use of semiconductors directly in the power supply path in order to achieve strict power quality standards. New and advanced algorithms are used in the process and calculated on-line to bring about the required fast response to voltage variations. Losses in high voltage semiconductors increase with increased operating frequencies. A balance between semiconductor power losses and power quality is achieved through control of power semiconductor switching frequencies. A predictive control algorithm to achieve high power quality and limit the power losses in the high power semiconductor switches through switching frequency control is discussed for a tap switched voltage regulator. The quality of power, voltage regulator topology and the control algorithm are discussed. Simulation results of output voltage and current are shown when the control algorithm is used to control the regulator. These results are verified by practical measurements on a synchronous buck converter.
AFRIKAANSE OPSOMMING: Die ontwikkeling van vinnige en doeltreffende verwerkers, programmeerbare toestelle en hoëdrywings halfgeleiers het gelei tot 'n groter gebruik van halfgeleiers direk in die kragtoevoer pad om streng elektriese toevoer kwaliteit standaarde te bereik. Nuwe en gevorderde algoritmes word gebruik in die proses en word aan-lyn bereken om die nodige vinnige reaksie tot spanningswisselinge te gee. Verliese in hoë-spannings halfgeleiers verhoog met hoër skakel frekwensies. 'n Balans tussen die halfgeleier drywingsverliese en spanningskwalteit is behaal deur die skakel frekwensie in ag te neem in die beheer. 'n Voorspellinde-beheer algoritme om ‘n hoë toevoerkwaliteit te bereik en die drywingsverliese in die hoëdrywingshalfgeleier te beperk, deur skakel frekwensie te beheer, is bespreek vir 'n tap-geskakelde spanning reguleerder. Die toevoerkwaliteit, spanningsreguleerder topologie en die beheer algoritme word bespreek. Simulasie resultate van die uittree-spanning en stroom word getoon wanneer die beheer algoritme gebruik word om die omsetter te beheer. Hierdie resultate is deur praktiese metings op 'n sinkrone afkapper.
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Effah, Francis Boafo. "Three-level Z-source hybrid direct AC-AC power converter topology." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14007/.
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Voltage source inverter (VSI) is the traditional power converter used to provide variable voltage and frequency from a fixed voltage supply for adjustable speed drive and many other applications. However, the maximum ac output voltage that can be synthesized by a VSI is limited to the available dc-link voltage. With its unique structure, the Z-source inverter can utilise shoot-through states to boost the output voltage and provides an attractive single-stage dc-ac conversion that is able to buck and boost the voltage. For applications with a variable input voltage, this inverter is a very competitive topology. The same concept can equally be extended to the two-stage matrix converter, where a single Z-source network is inserted in its virtual dc-link. The topology formed is, thus, quite straightforward. Its modulation is, however, non-trivial if advantages like voltage buck-boost flexibility, minimum commutation count, ease of implementation, and sinusoidal input and output quantities are to be attained simultaneously. This thesis presents two novel space vector modulation methods for controlling a three-level Z-source neutral point clamped VSI to enable the use of a boost function. The second of the two space vector modulation methods is then adopted and applied to a three-level, two-stage matrix converter with a Z-source network inserted in its virtual dc-link to increase the voltage transfer ratio beyond the intrinsic 86.6\% limit. Simulation results are supported by experimental verification from two laboratory prototype converters.
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Balakrishnan, Anand Kumar. "Soft switched high frequency ac-link converter." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3156.
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Zhou, Binxin. "Control techniques for a three-phase to three-phase AC/AC matrix converter." Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/1145.
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Mayes, Peter Richard. "A novel AC/DC bidirectional power converter." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239439.
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Van, Schalkwyk Christine. "Analysis and design of a voltage regulator based on an AC-to-AC converter." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53254.
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Thesis (MScEng)--University of Stellenbosch, 2003.ENGLISH ABSTRACT: This thesis discusses the analysis and design of a voltage regulator based on an AC-to-AC converter. A background study was performed on the best topology for the purpose. The chosen topology was analysed and the converter was designed in detail. A voltage sign-detector and an over-current detector were designed and built. They were used for control and protection. Three methods of control were investigated. The first was a slow but reliable method of computing the RMS value of the input voltage and then using that value and the RMS value of the desired output voltage to compute the duty ratio of the converter. The second method was fast and is an open-loop control method, where the measured input voltage and a reference value of the desired output voltage are used to compute the duty ratio. The third method is a closed-loop control method in which the input voltage, output voltage and the same reference values used in the second method are used to compute the duty ratio. All of these methods were implemented and tested.
AFRIKAANSE OPSOMMING: Hierdie tesis bespreek die analise en die ontwerp van 'n spannings reguleerder wat gebaseer is op 'n WS-na-WS omsetter. 'n Ondersoek was ingestelom die beste topologie te vind vir die doel. Die topologie wat gekies is, is toe geanaliseer en die omsetter is in detailontwerp. 'n Spannings-tekendetektor baan as ook 'n oorstroombeskermings baan was ontwerp en is gebou. Hierdie bane word gebruik vir die beheer en die beveiliging van die stelsel. Daar is drie metodes van beheer wat ondersoek is. Die eerste metode is stadig, maar betroubaar. Die metode bereken die WGK waarde van die intree spanning en gebruik dan die waarde en die WGK van die gewenste uittree spanning om die diens siklus van die omsetter uit te werk. Die tweede metode van beheer is vinnig en is 'n oop-lus metode van beheer. Hierdie metode maak gebruik van die gemete intreespanning en 'n verwysing van die gewensde uittree spanning om die dienssiklus uit te werk. Die derde metode is 'n geslote-lus beheer wat van die gamete intreespanning, die gemete uittreespanning en die verwysing soos die in die tweede beheermetode gebruik maak on die diens siklus uit te werk. AI die metodes was geimplementeer en getoets.
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You, Keping Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "A new bidirectional AC-DC converter using matrix converter and Z-source converter topologies." Awarded by:University of New South Wales, 2007. http://handle.unsw.edu.au/1959.4/37450.
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This thesis proposes a new bidirectional three-phase AC-DC power converter using matrix converter and Z-source inverter topologies. Advantages of the AC-DC matrix converter are the inherently controllable power factor, the tight DC voltage regulation, the wide bandwidth with quick response to load variation, the single-stage buck-voltage AC-to-DC power conversion; advantages of the z-source inverter are the increased reliability by allowing the shoot-through between upper and lower power switches of one inverter leg, insensitivity to DC bus voltage due to the extra freedom of controlling DC-link voltage. The proposed Matrix-Z-source converter (MZC) marries up both advantages of AC-DC matrix converter and Z-source inverter. It can achieve voltage-boost DC-AC inversion capable of variable voltage variable frequency (VVVF) AC output; it can achieve voltage-buck AC-DC rectification capable of inherent control over AC current phase angle and DC output regulation with a (VVVF) AC source supply. Both foresaid performance in DC-AC inversion and AC-DC rectification can be implemented in a simple open-loop control manner. Three constraints of VSI, in the bidirectional AC-DC power conversion, are the peak AC voltages are always less than DC-link voltage, closed-loop control has to be employed when DC regulation and/or AC current phase angle control are required, and AC voltage is sensitive to the variation of the DC-link voltage in DC-AC inversion. The voltage-boost inversion and/or voltage-buck rectification of MZC overcomes the first constraint; thus MZC enables the AC machine voltage increased higher than DC-link voltage hence advantages of running AC machine at relatively high voltages are enabled. The direct DC voltage regulation and inherent AC-current-phase-angle control of MZC overcomes the second constraint in an open-loop manner; hence a simplified system design is obtained with sufficient room for the further improvement by closed-loop control schemes. The extra freedom in controlling DC-link voltage of MZC overcomes the third constraint hence a DC source voltage adaptable inverter is obtained. This thesis focuses on the study of the feasibility of the proposed MZC through theoretical analysis and experimental verification. At first, the proposed MZC is conceptually constructed by examining the quadrant operation of AC-DC matrix converter and Z-source inverter. After the examination of the operating principles of both AC-DC matrix converter and Z-source inverter, the configuration of MZC is then proposed. The MZC has two operating modes: DC-AC inversion and AC-DC rectification. Circuit analysis for both operating modes shows that the new topology does not impose critical conflict in circuit design or extra restriction in parameterization. On the contrary, one version of the proposed MZC can make full advantage of Z-source network components in both operating modes, i.e. a pair of Z-source inductor and capacitor can be used as low-pass filter in AC-DC rectification. The modulation strategy, average modeling of system, and features of critical variables for circuit design of the proposed MZC were examined for each operating mode. Simulations of the proposed MZC and its experimental verification have been presented. Analytical models of conduction and switching losses of the power-switch network in different operating mode have shown that the losses in the MZC compare favorably with conventional VSI for a range of power factor and modulation indices.
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Ahmad, Khan Naveed. "Power Loss Modeling of Isolated AC/DC Converter." Thesis, KTH, Elektrisk energiomvandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109717.
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Several research activities at KTH are carried out related to Isolated AC/DC converters in order to improve the design and efficiency. Concerning the improvement in the mentioned constraints, losses of the elements in the prototype converter are modeled in this thesis work. The obtained loss model is capable of calculating the losses under different circumstances. The individual contribution of losses for each element at different conditions can be obtained, which is further useful in improving the design and therefore, efficiency. The losses in different elements of the converter, including power semiconductor devices, RC-snubbers, transformer and filter inductor at different operating points can be computed by using the obtained model. The loss model is then validated by comparing the analytical results with the measurements. The results based on developed loss model show consistency with the measured losses. The comparison at different conditions shows that, the difference between measured and analytical results ranges between 10% to 20 %. The difference is due to those losses which are disregarded because of their negligible contribution. On the other hand, it is also observed that if the neglected losses are counted, the difference reduces up to 10%.
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Perera, Lasantha Bernard. "Multi Level Reinjection ac/dc Converters for HVDC." Thesis, University of Canterbury. Electrical and Computer Engineering, 2006. http://hdl.handle.net/10092/1085.
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A new concept, the multi level voltage/current reinjection ac/dc conversion, is described in this thesis. Novel voltage and current source converter configurations, based on voltage and current reinjection concepts are proposed. These converter configurations are thoroughly analyzed in their ac and dc system sides. The fundamentals of the reinjection concept is discussed briefly, which lead to the derivation of the ideal reinjection waveform for complete harmonic cancellation and approximations for practical implementation. The concept of multi level voltage reinjection VSC is demonstrated through two types of configurations, based on standard 12-pulse parallel and series connected VSC modified with reinjection bridges and transformers. Firing control strategies and steady state waveform analysis are presented and verified by EMTDC simulations. The multi level current reinjection CSC is also described using two configurations based on standard 12-pulse parallel and series connected CSC modified with associated reinjection circuitry. Firing control strategies and steady state waveform analysis are presented and verified by EMTDC simulations. Taking the advantage of zero current switching in the main bridge valves, achieved through multi level current reinjection, an advanced multi level current reinjection scheme, consisting thyristor main bridges and self-commutated reinjection circuitry is proposed. This hybrid scheme effectively incorporates self-commutated capability into a conventional thyristor converter. The ability of the main bridge valves to commutate without the assistance of a turn-off pulse or line commutating voltage under the zero current condition is explained and verified by EMTDC simulations. Finally, the applications of the MLCR-CSC are discussed in terms of a back to back HVDC link and a long distance HVDC transmission system. The power and control structures and closed loop control strategies are presented. Dynamic simulation is carried out on PSCAD/EMTDC to demonstrate the two systems ability to respond to varying active and reactive power operating conditions.
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Ratanapanachote, Somnida. "Applications of an electronic transformer in a power distribution system." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2756.
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In electrical power distribution and power electronic applications, a transformer is an indispensable component which performs many functions. At its operating frequency (60/50 Hz), it is one of the most bulky and expensive components. The concept of the electronic transformer introduced previously has shown considerable reduction in size, weight, and volume by operating at a higher frequency.
In this dissertation, the concept of the electronic transformer is further extended to the auto-connected phase-shifting type to reduce harmonics generated by nonlinear loads. It is shown that with the addition of primary side and secondary side AC/AC converters achieves phase-shifting. With the addition of converters, magnetic components are operated at a higher frequency to yield a smaller size and weight. Two types of auto-connected electronic transformer configurations are explored. In the first configuration, the secondary converter is eliminated and the output is suitable for rectifier type loads such as adjustable speed drives. In the second configuration, the
secondary converter is added to obtain a sinusoidal phase-shifted AC output voltage. This approach is applicable in general applications. With the proposed approaches, the th and 7th harmonic in utility line currents, generated by two sets of nonlinear loads, are subtracted within the electronic transformer, thereby reducing the total harmonic distortion (THD) of the line current. The analysis and simulation results are presented.
In the second part of the dissertation, the electronic transformer concept is applied to a telecommunication power supply (-48 VDC) system. The proposed approach consists of a matrix converter to convert the low frequency three-phase input AC utility to a high frequency AC output without a DC-link. The output of the matrix converter is then processed via a high frequency isolation transformer to produce -48 VDC. Digital control of the system ensures that the output voltage is regulated and the input currents are of high quality, devoid of low frequency harmonics and at near unity input power factor under varying load conditions. Due to the absence of DC-link electrolytic capacitors, the power density of the proposed rectifier is shown to be higher. Analysis, design example and experimental results are presented from a three-phase 208 V, 1.5 kW laboratory prototype converter.
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Sastry, Jyoti. "Direct AC control of grid assets." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41109.
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The objective of the proposed research is to investigate feasible approaches to dynamic control of the power grid. Growth in the demand for electric power, and an increase in the penetration of renewable energy resources are causing congestion on an already aging power grid. Conventional grid control involves the use of static assets that operate on long time scales. These assets provide no dynamic control on the grid, and are typically used for scheduled support. Existing solutions (FACTS devices) to dynamic grid control have seen minimal market penetration because of high cost and low reliability. The proposed research provides a solution for dynamic control of the power grid that augments existing grid assets with a thin AC converter (TACC) to realize enhanced dynamic control. The TACC is a direct AC converter with filter elements and no bulk energy storage that dynamically reflects the asset value on the grid. The converter has a fail-normal mode of operation that returns the asset to its initial operating state, thereby not degrading system reliability. Some applications of TACCs include Inverter-Less STATCOMs and Controllable Network Transformers, which are realized by augmenting shunt VAR capacitors and load tap changers respectively. The principle of virtual quadrature sources is proposed to enable conditioning of AC voltages and currents. The concept is a novel method to realize control of phase angle and, or harmonics in single-phase AC converters, with no bulk energy storage. This concept is used to control the TACC and provides the asset with significantly enhanced control capabilities. Scaling of the TACC to utility voltage and power levels has been addressed by proposing a novel multilevel direct AC converter. The concept proposes the use of commercially available low cost semiconductor devices to realize high power converters. The specific application chosen to validate the concept of TACCs, through a medium voltage design, is the Inverter-less STATCOM.
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Alsolami, Mohammed Faham. "Wide Bandgap (WBG) Devices Based Switched Capacitor Multiport Multilevel SinglePhase AC/DC/AC Converter for UPS Applications." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461327268.
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Mino, Kazuaki. "Novel hybrid unidirectional three-phase AC-DC converter systems /." [S.l.] : [s.n.], 2009. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18185.
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Daniele, Matteo. "A single-stage power factor corrected AC/DC converter." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0018/MQ39474.pdf.
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Trubitsyn, Aleksey. "High efficiency DC/AC power converter for photovoltaic applications." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/60190.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Includes bibliographical references (p. 217-218).
This thesis presents the development of a microinverter for single-phase photovoltaic applications that is suitable for conversion from low-voltage (25-40V) DC to high voltage AC (e.g. 240VAC,RMS). The circuit topology is based on a full-bridge series resonant inverter, a high-frequency transformer, and a novel half-wave cyclo-converter. The operational characteristics are analyzed, and a multidimensional control technique is utilized to achieve high efficiency, encompassing frequency control and inverter and cyclo-converter phase shift control. An experimental prototype is demonstrated in DC/DC conversion mode for a wide range of output voltages. The proposed control strategy is shown to allow for accurate power delivery with minimal steps taken towards correction. The prototype achieves a CEC averaged efficiency of approximately 95.1%. Guidelines for optimization are presented along with experimental results which validate the method.
by Aleksey Trubitsyn.
S.M.
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Salazar, Nathaniel Jay Tobias. "High frequency AC power converter for low voltage circuits." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77026.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74-76).
This thesis presents a novel AC power delivery architecture that is suitable for VHF frequency (50-100MHz) polyphase AC/DC power conversion in low voltage integrated circuits. A complete AC power delivery architecture was evaluated demonstrating the benefits of delivering power across the interconnect at high voltage and lower current with on- or over-die transformation to low voltage and high current. Two approaches to polyphase matching networks in the transformation stage are compared: a 3-phase system with separate single-phase matching networks and individual full bridge rectifiers, and a 3-phase delta-to-wye matching network and a 3-phase rectifier bridge. In addition, a novel switch-capacitor rectifier capable of 3V, 1W output, was evaluated as an alternative circuit to the diode rectifiers. A 50MHz prototype of each version of the system was designed and built for a 12:1 conversion ratio with 24Vpp line-to-line AC input, 2V DC output and 0.7W output power. The measured overall system efficiency is about 63 % for the 3-phase delta system. Although the application is intended for an integrated CMOS implementation, this thesis primarily focuses on discrete PCB level realizations of the proposed architectures to validate the concept and provide insights for future designs.
by Nathaniel Jay Tobias Salazar.
M.Eng.
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Wheeler, Patrick W. "A matrix converter for variable speed AC motor drives." Thesis, University of Bristol, 1993. http://hdl.handle.net/1983/1eec4275-808a-4125-813b-4f6e00881f44.
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Wang, Kunrong. "High-Frequency Quasi-Single-Stage (QSS) Isolated AC-DC and DC-AC Power Conversion." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/29394.
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The generic concept of quasi-single-stage (QSS) power conversion topology for ac-dc rectification and dc-ac inversion is proposed. The topology is reached by direct cascading and synchronized switching of two variety of buck or two variety of boost switching networks. The family of QSS power converters feature single-stage power processing without a dc-link low-pass filter, a unidirectional pulsating dc-link voltage, soft-switching capability with minimal extra commutation circuitry, simple PWM control, and high efficiency and reliability.
A new soft-switched single-phase QSS bi-directional inverter/rectifier (charger) topology is derived based on the QSS power conversion concept. A simple active voltage clamp branch is used to clamp the otherwise high transient voltage on the current-fed ac side, and at the same time, to achieve zero-voltage-switching (ZVS) for the switches in the output side bridge. Seamless four-quadrant operation in the inverter mode, and rectifier operation with unity power factor in the charger (rectifier) mode are realized with the proposed uni-polar center-aligned PWM scheme. Single-stage power conversion, standard half-bridge connection of devices, soft-switching for all the power devices, low conduction loss, simple center-aligned PWM control, and high reliability and efficiency are among its salient features. Experimental results on a 3 kVA bi-directional inverter/rectifier prototype validate the reliable operation of the circuit. Other single-phase and three-phase QSS bi-directional inverters/rectifiers can be easily derived as topological extensions of the basic QSS bi-directional inverter/rectifier.
A new QSS isolated three-phase zero-voltage/zero-current-switching (ZVZCS) buck PWM rectifier for high-power off-line applications is also proposed. It consists of a three-phase buck bridge switching under zero current and a phase-shift-controlled full-bridge with ZVZCS, while no intermediate dc-link is involved. Input power and displacement factor control, input current shaping, tight output voltage regulation, high-frequency transformer isolation, and soft-switching for all the power devices are realized in a unified single stage. Because of ZVZCS and single-stage power conversion, it can operate at high switching frequency while maintaining reliable operation and achieving higher efficiency than standard two-stage approaches. A family of isolated ZVZCS buck rectifiers are obtained by incorporating various ZVZCS schemes for full-bridge dc-dc converters into the basic QSS isolated buck rectifier topology. Experimental and simulation results substantiate the reliable operation and high efficiency of selected topologies.
The concept of charge control (or instantaneous average current control) of three-phase buck PWM rectifiers is introduced. It controls precisely the average input phase currents to track the input phase voltages by sensing and integrating only the dc rail current, realizes six-step PWM, and features simple implementation, fast dynamic response, excellent noise immunity, and is easy to realize with analog circuitry or to integrate. One particular merit of the scheme is its capability to correct any duty-cycle distortion incurred on only one of the two active duty-cycles which often happens in the soft-switched buck rectifiers, another merit is the smooth transition of the input currents between the 60o sectors. Simulation and preliminary experimental results show that smooth operations and high quality sinusoidal input currents in the full line cycle are achieved with the control scheme.Ph. D.
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Shen, Jian. "GTO Pulsed Width Modulated (PWM) converter for railway traction applications." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308484.
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Yildirim, Dogan. "Field Oriented Control Of A Permanent Magnet Synchronous Motor Using Space Vector Modulated Direct Ac-ac Matrix Converter." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614302/index.pdf.
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The study designs and constructs a three-phase to three-phase direct AC&ndashAC matrix converter based surface mounted permanent magnet synchronous motor (PMSM) drive system. First, the matrix converter topologies are analyzed and the state-space equations describing the system have been derived in terms of the input and output variables. After that, matrix converter commutation and modulation methods are investigated. A four-step commutation technique based on output current direction provides safe commutation between the matrix converter switches. Then, the matrix converter is simulated for both the open-loop and the closed-loop control. For the closed-loop control, a current regulator (PI controller) controls the output currents and their phase angles. Advanced pulse width modulation and control techniques, such as space vector pulse width modulation and field oriented control, have been used for the closed-loop control of the system. Next, a model of diode-rectified two-level voltage source inverter is developed for simulations. A comparative study of indirect space vector modulated direct matrix converter and space vector modulated diode-rectified two-level voltage source inverter is given in terms of input/output waveforms to verify that the matrix converter fulfills the two-level voltage source inverter operation. Following the verification of matrix converter operation comparing with the diode-rectified two-level voltage source inverter, the simulation model of permanent magnet motor drive system is implemented. Also, a direct matrix converter prototype is constructed for experimental verifications of the results. As a first step in experimental works, filter types are investigated and a three-phase input filter is constructed to reduce the harmonic pollution. Then, direct matrix converter power circuitry and gate-driver circuitry are designed and constructed. To control the matrix switches, the control algorithm is implemented using a DSP and a FPGA. This digital control system measures the output currents and the input voltages with the aid of sensors and controls the matrix converter switches to produce the required PWM pattern to synthesize the reference input current and output voltage vectors, as well. Finally, the simulation results are tested and supported by laboratory experiments involving both an R-L load and a permanent magnet synchronous motor load. During the tests, the line-to-line supply voltage is set to 26 V peak value and a 400 V/3.5 kW surface mounted permanent magnet motor is used.
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Stejskal, Jiří. "Měnič 12V DC/230V AC." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218761.
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This diploma thesis describes particular parts of power inverter such as gate driver, DSC, LC filter, low power supply, DC/DC converter and four-quadrant bridge and manner of its control by digital signal controller. Inverter is designated for generating of a mobile artificial electric grid (for example in a car).
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Yang, Xiaoguang Miu Karen Nan. "Unbalanced power converter modeling for AC/DC power distribution systems /." Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1231.
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Santos, Heron Alves dos. "Design of a controlled single-phase ac-dc converter for interconnection of DC and AC buses of a microgrid." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12977.
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The recent growth expectation of the participation of solar-photovoltaic energy sources in the power generation matrix has significantly increased the number of grid-connected systems. For connection to power grid, it is essential to use a dc-ac converter, which is able to suit the characteristics of the power provided by the photovoltaic modules to grid parameters. This dissertation presents a project proposal of a 2 kW single phase dc-ac converter for connecting a 311 V dc bus to a 220 Vrms ac bus of a microgrid. The proposed converter is bidirectional and allows, when necessary, the power flow from ac to dc bus. The study shows, through simulation and prototype implementation in the laboratory, that with the application of an appropriate control strategy it is possible to control the direction of power flow, as well as properly modulating the current flowing between two buses, dc, powered by photovoltaic panels and the battery bank, and the ac, at grid side. The prototype had a yield of about 91% and has injected electric current with low harmonic content (THDi less than 5%).A recente expectativa de crescimento da participaÃÃo da energia solar-fotovoltaica na matriz de geraÃÃo de energia elÃtrica aumentou significativamente o nÃmero de conexÃes desses sistemas à rede elÃtrica. Para que a interligaÃÃo com a rede elÃtrica convencional seja possÃvel, à indispensÃvel a utilizaÃÃo de conversores CC/CA, capazes de adequar as caracterÃsticas da energia disponibilizada pelos mÃdulos fotovoltaicos aos padrÃes da rede. Esta dissertaÃÃo apresenta uma proposta de projeto de conversor CC/CA de 2 kW para conexÃo de dois barramentos de uma microrrede, um CC em 311 V e outro CA em 220 Vrms. O conversor proposto à bidirecional e permite, quando necessÃrio, o fluxo de energia elÃtrica do barramento CA para o CC. O estudo realizado mostra, atravÃs de simulaÃÃes e de implementaÃÃo de protÃtipo em laboratÃrio, que com a aplicaÃÃo de uma estratÃgia de controle adequada à possÃvel controlar o sentido do fluxo de potÃncia do conversor, assim como modular apropriadamente a corrente que flui entre dois barramentos, o CC, alimentado por painÃis fotovoltaicos e por banco de baterias, e o barramento CA, do lado da rede elÃtrica. O protÃtipo desenvolvido apresentou rendimento de cerca de 91% e forneceu corrente elÃtrica de baixo conteÃdo harmÃnico (THDi menor que 5%).
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Steckler, Pierre-Baptiste. "Contribution à la conversion AC/DC en Haute Tension." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI075.
Full textAbstract:
Le courant alternatif (AC) se prêtant bien à la majorité des problématiques de production, de transport et de distribution de l'électricité, on comprend qu'il soit massivement utilisé. Cependant, depuis plus d'un siècle, les bénéfices du courant continu haute tension (HVDC, pour High Voltage Direct Current) pour les longues distances sont bien connus. Aux interfaces, des convertisseurs AC/DC sont requis, leur composition évoluant au fil des avancées technologiques. Après avoir présenté les spécificités du HVDC et les contraintes qu'il introduit sur les convertisseurs AC/DC, ce manuscrit se focalise sur trois topologies : Modular Multilevel Converter (MMC), Alternate Arm Converter (AAC) et Series Bridge Converter (SBC). Elles sont présentées, dimensionnées et analysées en détail, puis comparées de façon quantitative en utilisant des indicateurs de performance originaux. Il en ressort que le MMC et le SBC sont particulièrement intéressants. La méthode de commande conventionnelle du MMC est ensuite présentée et ses propriétés structurelles sont mises en évidence. Une première loi de commande originale est présentée, avec des performances similaires mais une complexité inférieure à l'état de l'art. La seconde est non linéaire, basée sur la théorie de la platitude différentielle, et permet un suivi de puissance très rapide tout en assurant la stabilité exponentielle globale du système. Ces lois de commande sont évaluées en simulation, avec un modèle moyen et un modèle détaillé intégrant 180 sous-modules par bras. La dernière partie concerne le SBC. Après l'avoir modélisé, des résultats concernant une analyse structurelle de la topologie sont présentés ainsi qu'une loi de commande originale. Le rôle fondamental du transformateur pour les convertisseurs à structure série comme le SBC est souligné. Enfin, les performances de la loi de commande proposée sont testées en simulationAs Alternating Current (AC) is well suited for most of the production, transmission, and distribution applications, its massive use is easy to understand. However, for over a century, the benefits of High Voltage Direct Current (HVDC) for long-distance energy transmission are well known. To connect both, AC/DC converters are mandatory, whose nature evolves with technological progress. After the problematic induced by HVDC on AC/DC converters is presented, this manuscript is focused on three topologies: Modular Multilevel Converter (MMC), Alternate Arm Converter (AAC) and Series Bridge Converter (SBC). They are presented, sized, analyzed thoroughly, and compared in quantitative terms, using original key performance indicators. It appears that MMC and SBC are particularly promising. The conventional control method of the MMC is then presented, and its structural properties are highlighted. A first original control law is presented, with similar performances but less complexity than the state-of-the-art. A second control law, non-linear and based on differential flatness theory, is introduced. It allows a very fast power tracking response while ensuring the global exponential stability of the system. These control laws are tested in simulation, using an average model and a detailed model with 180 sub-modules per arm. The last part is dedicated to the SBC. After a modeling step, some results regarding its structural analysis are presented, and an original control law is introduced. The essential role of the transformer for series converters like the SBC is highlighted. Finally, the performance of the proposed control law is assessed in simulation
26
Gitau, Michael N. "Optimal PWM switching strategy for single-phase AC-DC converters." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/7205.
Full textAbstract:
The thesis describes an optimal selective harmonic elimination strategy suitable for singlephase AC-DC converter-fed traction drives. The objective is to eliminate low-order supply current harmonics, including those injected into the supply due to load-side current ripple. Other advantages that the switching strategy has to offer over phase-control include improved supply power factor, reduced VA consumption for a given demand speed and load, reduced torque and speed ripple and smaller armature circuit smoothing inductance. The effect of field current boost on the dynamic response of the drive is also described. It is shown that field boost helps to reduce the speed rise-time by increasing the electromagnetic torque available during acceleration periods. Closed-loop control of a 4-quadrant DC drive is described and a comparison made between the performance of PID-control and pseudo-derivative feedback control. It is shown that pseudo-derivative feedback control has several advantages to offer, amongst which are ease of tuning of the controller gains and a superior performance following load torque disturbances. A laboratory size drive system was designed and built, and used to validate simulation predictions for both the switching strategy and pseudo-derivative feedback control. A microcontroller based hardware implementation of both the switching strategy and a digital pseudo-derivative feedback controller was adopted, with the switching strategy being implemented using an off-line approach of precalculating the switching angles and storing these in look-up tables. The armature voltage controller comprises a dual-converter employing IGBTs as switching devices. The use of IGBTs allows higher switching frequencies at significant power levels than would be possible if GTOs were used. It also simplifies the gate drive circuit design and minimises the need to use snubber circuits.
27
LI, QIANG. "A SINGLE-PHASE DUAL-OUTPUT AC-DC CONVERTER WITH HIGH QUALITY INPUT WAVEFORMS." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/242.
Full textAbstract:
A single-phase, buck-boost based, dual-output AC-DC converter is studied in this thesis. The converter has two DC outputs with opposite polarities, which share the same ground with the input power line. The power stage performance, including the input filter, is studied and procedure to select power components is given. The circuit model is analyzed to develop appropriate control. Zerocrossing distortion of the source input current is addressed and a solution is proposed. Experimental results are satisfactory in that a high power factor line current results for steady-state operation.
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Dasco, Antony. "Contrôle et modélisation du convertisseur multi-modulaire AC-AC pour les liaisons offshore à haute tension et basse fréquence." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT057/document.
Full textAbstract:
L’objectif principal de cette thèse consiste à développer des stratégies de modélisation et de contrôle pour la conversion de fréquence en utilisant un convertisseur multi-modulaire sans utilisation de lien en continu. Ce convertisseur est nécessaire pour l’intégration des énergies renouvelables offshore dans un réseau de transport à basse fréquence. La basse fréquence électrique profite à la fois des avantages des réseaux alternatif et continu. L’utilisation de convertisseurs modulaires dans ces réseaux permet, entre autres, de supprimer le transformateur du côté de la basse fréquence électrique. Dans cette optique, l’énergie est convertie depuis la fréquence nominale à 50 Hz ou 60 Hz (considérée comme la haute fréquence) vers un tiers de 50 Hz. Le convertisseur est aussi capable de transformer d’autres valeurs de fréquence. Dans un premier temps, la méthode de modélisation du convertisseur est reliée à la théorie du transformateur de voltage triphasé avec un couplage en YDY. En deuxième lieu, l’application du théorème de superposition nous permet d’évaluer séparément la contribution de chaque fréquence. Dans un dernier temps, le contrôle principal du convertisseur utilise des correcteurs résonants, capables donc de travailler directement avec les courants internes du convertisseur qui sont à deux fréquences nominales. Grâce au découplage entre l’entrée du convertisseur et sa sortie, les défauts et les situations de déséquilibre ne se propagent pas vers la sortie du convertisseur, fonctionnement requis pour l’application en offshoreThe purpose of this thesis is to develop strategies to model and control a modular multilevel converter in order to transform frequency without passing through a direct current link. This converter is needed for application in offshore systems where the energy, produced by the offshore renewables, is transmitted using low frequency links. Low frequency presents benefits from alternative and direct current technologies. Moreover, a voltage transformer is not required at the low frequency side when the proposed converter is used as a frequency transformer. In this scenario, frequencies are converted from the highest nominal frequency (50 Hz or 60 Hz) to one third of 50 Hz. Conversion to other frequency values has been tested as well using the same converter. A methodology based on the electrical transformer theory when connected in YΔY coupling and, the superposition theorem to separate the contribution from both frequencies, are proposed to link these currents with the two three-phase systems at different nominal frequencies. Resonant controllers are introduced to efficiently correct internal current signals of the converter that nominally are constituted of two frequencies: input and output frequencies. The converter is able to decouple the input side from the output. Therefore, faults and unbalanced conditions on the input side are not propagated to the output-side of the converter, which is required for offshore applications
29
Ismail, Nasser. "A single stage full bridge power factor corrected AC/DC converter." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq26004.pdf.
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Kao, Chuan-yi, and 高專益. "High-frequency based AC/AC converter for AC voltage regulator." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/53937183680373787423.
Full textAbstract:
碩士南台科技大學
電機工程系
98
This thesis presents studies and designs of analog circuits based AC voltage regulator, including low-frequency isolation and high-frequency isolation structures. The low-frequency isolation based AC voltage regulator is made up of an AC chopper with a compensating transformer in series with AC line, to obtain an in-phase voltage with respect to AC line to compensate the voltage variations. In contrast to low-frequency structure, the high-frequency isolation based AC voltage regulator is presented to improve the bulky and heavy of low-frequency transformers. The proposed idea can be used to regulate both the overvoltage and undervoltage situations with bi-directional energy transmission function. Conventional ac voltage compensation techniques have been reviewed, and high frequency transformer based architecture is proposed to achieve the desired function. Finally, the simulation and experimental results prove the practicability for these topologies.
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Ho, Chien-Han, and 何建翰. "Implementation of Single Phase Three-switch AC/AC Converter." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/fvk652.
Full textAbstract:
碩士國立虎尾科技大學
電機工程研究所
100
In the thesis, a single phase three-switch AC/AC converter is implemented. The converter consists of three power switches, input and output inductors, three capacitors, and an output filter capacitor. Two operation modes, half-bridge rectifier mode and half-bridge inverter, are adopted. Use state equations of traditional single phase full-bridge rectifier to derive the ratio of capacitor and control strategy of the converter. By TMS320F2812 and control software VisSim, the digital close-loop control is achieved to get unity power factor, sinusoidal input current, adjustable output voltage, and adjustable output frequency, etc.. Finally, some experimental results verify the feasibility of converter.
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Chen, Jyun-Ren, and 陳俊任. "A Novel Single-Phase Three-Switch AC/AC Converter." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/77sj33.
Full textAbstract:
碩士國立虎尾科技大學
電機工程研究所
99
In this thesis, a novel single-phase three-switch AC/AC converter is proposed. The proposed converter consists of three power switches, three capacitors and two inductors. Based on the generalized zero vector (GZV) control strategy, the proposed converter has several advantages such as single stage control, input unity power factor, sinusoidal input/output current, energy regeneration, and low cost etc.. Besides, a fully digital control TMS320F2812 digital signal processor (DSP) and VisSim simulation program are adopted to implement the control circuit. Finally, some experimental results are presented to verify the feasibility of the proposed converter.
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Faveluke, Alex. "Hardware design and protection issues in an AC/AC converter." Thesis, 1997. http://hdl.handle.net/1957/33718.
Full textAbstract:
An AC/AC converter has been designed and implemented for the purpose of
providing a modular drive system with a Brushless Doubly-Fed Machine (BDFM.) This
converter is to be used in laboratory testing and also as part of a demonstration system in
the field.
All hardware needed to start and run the BDFM is now consolidated into a single
NEMA standard frame electrical equipment box. This allows easy transportation and
setup of the drive system, and will enable the BDFM drive system to be directly
compared with existing induction machine based drive systems.
Converter subsystem overviews in the body of the text and comprehensive
schematics in the appendices of this thesis describe all circuitry included in the drive
system. Sufficient construction detail is given to allow for duplication of this converter
by qualified technical personnel. While not tailored for mass production, this converter
may provide a starting point for a commercially viable design.Graduation date: 1998
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Yang, Chen-Chih, and 楊鎮誌. "A Novel Three-phase AC/AC Converter Using Six Switches." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/drwr9z.
Full textAbstract:
碩士國立虎尾科技大學
電機工程研究所
100
In this thesis, a novel three-phase AC/AC converter is proposed. The proposed converter consists of six power switches, three capacitors, three input inductors and three output inductors. The proposed converter has several advantages such as sinusoidal input-output current, adjustable frequency, unity input power factor and lower switch cost etc.. Based on the sinusoidal pulse width modulation techniques and zero vector control strategy, the converter combines three-phase AC/DC converter and three-phase DC/AC inverter to generate a single-stage converter controlled in the same period. By fixed capacitor ratio, the duty functions of converter and inverter are operated in optimum period for more stable control. The software VisSim and TI TMS320F2812 are adopted to implement the proposed converter. Besides, the mathematic model of the proposed converter is established by the state average technique. Finally, some experimental results are compared with the proposed theory for verification.
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Wu, Yue-Lin, and 吳岳霖. "Bi-Directional AC/DC Converter." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/454xtz.
Full textAbstract:
碩士國立臺北科技大學
電機工程系所
93
The thesis is dedicated to the design and implementation the bi-directional AC/DC converters for the front-end of inverter. The developed converter is modulated by space vector modulation and the related controlled quantities are referred to synchronous frame. The controller consists of multiple control loops, which include inner current loop and external voltage loop to achieve fast response. The inner loop is based upon direct current control and the voltage decouple to achieve current tracking, and the external loop controls the output voltage to follow the desired DC voltage value by balancing of instantaneous power between input and output. The developed converter improves the input power factor to approximate unity power factor and reduces the total harmonic distortion of current less than 5%. The low order harmonics are reduced and thereby decreasing the harmonic pollution. The specifications of the system include: the input voltage is AC 220 V/60 Hz, output power 1 kW, carrier frequency is 15 kHz, power factor is higher than 0.9, and the total harmonic distortion of current is less than 5%. The simulation software is developed based upon the platform of Matlab® -Simulink® and the experimental set-up is based on the dSPACE digital control board. The power devices of converter are controlled by the three-phase gating signals generated by space vector modulation technique. To reduce the number of sensor, a current estimation method is proposed to give the DC-link current. The feasibility of the proposed method is verified by simulation and experimental results.
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Ho, Wen-Jung, and 何文榕. "Optimizing Single-Phase AC/DC/AC Converter with PFC-Preregulator Improvement." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/30363357595270470618.
Full textAbstract:
博士國立臺灣大學
電機工程學系
85
The research of the dissertation focuses on the topologies of single-phase AC/DC/AC converter with pre-staged power-factor- correction (PFC). In the beginning, new topologies for PFC- prestaged AC/DC/AC converter are presented. The introduction of common-neutral connection simplifies the conventional connection of AC/DC/AC structure, and gives new topologies that still have good performance, conform with output safety regulations and have other advantages such as requiring fewer power devices and having loweconduction losses. Then a new on-line uninterruptible power supply (UPS) structure is also presented. It consists of a dual-functional PFC substituting for an inevitable battery- voltage booster thereby simplifying the complexity of power stage. Finally an even simpler topology of power stage for UPS applications is to be shown. This new single-conversion UPS mainly consists of a minimized power converter structure which is capable of providing specified constant output voltage, phase-controlled battery charr, and input-power-factor improvement.
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Chang, Shih-Yuan, and 張仕原. "Study and Realization of a Soft-Switching Single-Phase AC/AC Converter." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/50678993699955599309.
Full textAbstract:
碩士國立宜蘭大學
電機工程學系碩士班
97
A single-phase soft-switched series-resonant ac chopper without auxiliary switches is presented. The presented single-phase ac chopper is configured by a series-resonant conversion without cycloconversion and auxiliary switches. The proposed single-phase ac chopper is a series resonator with four main switches to configure adaptively the resonant voltage robes. The output sinusoidal voltage is synthesized by a series of sinusoidal amplitude quasi-sinusoidal pulses (QSPs) following the input voltage amplitude. The presented single-phase ac chopper is operated by frequency modulation with a constant-on time control. Waveform syntheses for the output sinusoidal voltage are clearly derived. A type design example of a 600W single-phase soft-switching ac chopper is examined to assess the system performance. The power efficiency is over 92％ when the output power is at maximum output rated power. The total harmonic distortion (THD) when the output power is at maximum output rated power is within 5％.
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Chen, Guan-Ying, and 陳冠穎. "A Novel Single-stage Single-phase AC to Three-phase AC Converter." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/7dv95n.
Full textAbstract:
碩士國立虎尾科技大學
電機工程研究所
100
This thesis proposes a novel single-stage single-phase AC to three-phase AC converter. Based on a zero vector technique, the proposed converter combines a single-phase full-bridge with three-phase full-bridge to form a single-stage circuit structure. The converter has unity power factor and sinusoidal input current in input side. Adjustable amplitude and frequency of three-phase current source are in output side. The proposed converter consists of eight power switches, one capacitor, one boost inductor and three output inductors. It’s worth mentioning that ten switches of the traditional converter can reduce to eight, and this can reduce cost and improve efficiency obviously. Besides, general solution of the switching duty ratio is obtained by using the state space averaging technique. Furthermore, employing the three-phase dead-band control can decrease the ratio of 1/3 times switching number. Consequently, this reduce the switching loss, and improves efficiency of the converter. In the control circuit, both VisSim simulation and DSP TMS320F2812 are employed to finish digital control for power factor correction of the input side and feedback control of the output side. Finally, some experiment results are presented to verify the feasibility of the proposed converter.
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Chang, Yu-wei, and 張育瑋. "Implementation of a Single-Phase AC/AC Converter With Adjustable Output Voltage." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/91265856663241860248.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
103
The thesis studies the implementation of an adjustable single-phase AC/AC converter. The hardware includes the buck-boost converter with bi-directional switches to achieve AC/AC conversion. The software is executed by using a digital signal processor, typed TMS320F2808. By measuring the feedback signals, the output voltage can keep as a constant under a variable input voltage and an external load disturbance condition. In addition, the output voltage can be adjusted according to the different input voltage commands. The thesis focuses on the basic principle and implementation. A single-phase AC/AC converter with 90~110V input voltage, 34~220V output voltage, 150W maximum power, 0.93 power factor has been implemented. Experimental results can validate the simulation waveforms to show the feasibility and correctness of the proposed method.
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Chen, Hsin-hsuan, and 陳信炫. "Development of AC-DC-AC Power Converter for Small Wind Power Systems." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/14261835836303093220.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
98
This thesis presents the analysis and design of power converters for small wind generators. The system consists of three-phase permanent-magnet synchronous generator, rectifier and inverter, which can transfer the generator power from varying-frequency and varying-voltage to single-phase for grid connection. The ac-dc power converter uses three-phase independent connections of totem-pole converter to keep dc-link voltage constant and exercise maximum power-point tracking. The single-phase inverter can provide the generator power to grid. The proposed system uses Matlab-Simulink/Simpower to simulate rectifier and inverter. The simulated results obtained serve as the basis for system implementation and performance evaluation. The high-performance and low-cost digital signal processor TMS320F2808 is used to control the power converter. An experimental system is built. The power converter supplies 780W with the current total harmonic distortion of generator of about 14.11%, while the current total harmonic distortion of single-phase output under grid connection is about 10.97%. The corresponding overall efficiency of 86.6 % is obtained using three-phase independent connections of totem-pole power converter.
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Filipe, Luís Paulo da Silva. "Simulação de um conversor AC/AC multinível." Master's thesis, 2019. http://hdl.handle.net/10400.13/2353.
Full textAbstract:
O desenvolvimento do mercado energético até os dias de hoje implica a utilização de conversores eletrónicos de potência capazes de lidar com valores elevados de tensão e potência, criando a necessidade de ser desenvolvido um novo conceito: a conversão multinível. Neste trabalho realiza-se a simulação de um conversor AC/AC multinível Neutral Point Clamp (NPC) trifásico bidirecional, capaz de controlar tensões com amplitudes e frequências variáveis, sendo viável para diversas aplicações. São estudadas individualmente as componentes retificadora (AC/DC) e inversora (DC/AC) do conversor, assim como a conversão AC/AC costas com costas, sendo realizados diversos testes relevantes a uma ligação entre duas redes distintas que, tendo um valor de tensão fixo, são controladas as amplitudes e a forma de onda das correntes AC. É também estudado um caso de aplicação a uma ligação High Voltage Direct Current (HVDC), onde é introduzido um cabo entre as componentes retificadora e inversora. Considerando todos os testes realizados ao conversor nas diferentes topologias, é possível afirmar que o conversor multinível apresenta um desempenho relevante, sendo capaz de controlar a amplitude e frequência das correntes trifásicas e a amplitude da tensão DC, sempre com erros inferiores a 10% e mantendo o Fator de Potência (FP) quase unitário. Este conversor é suficientemente robusto para suportar variações bruscas nos valores de referência, assim como a aplicação a um sistema bidirecional, onde as grandezas já descritas convergem num tempo máximo de 0,6 s (três ciclos da Rede Elétrica de Energia - REE).The development of the energetic market until today requires the utilization of electronic power converters able to deal with high values of voltage and power, creating the need of developing a new concept: multilevel conversion. In this project it is simulated an AC/AC multilevel NPC three-phase converter capable of transferring energy in both ways, controlling voltages with variable amplitude and frequency, being reliable to multiple applications. The rectifier (AC/DC) and inverter (DC/AC) components are studied individually, just like back-to-back AC/AC conversion, being tested multiple interesting case scenarios for a connection between two distinctive energy grids where, having a fixed voltage level, the amplitude and waveform of AC currents are controlled instead. It is also studied a specific application case scenario of a HVDC link, where a cable is introduced between the rectifier and inverter. Considering the results of the tests realized to all topologies analyzed, it is possible to say the multilevel converter has a positive performance, being able to control the waverforms of the three-phase currents and DC voltage with errors below 10% of the reference, keeping the power factor always near 1. This converter can handle sudden variations of the different reference values, including a change in the power flow direction, where all the variables controlled converge to the new references in a maximal time of 0,6s.
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Amirabadi, Mahshid. "Soft-Switching High-Frequency AC-Link Universal Power Converters with Galvanic Isolation." Thesis, 2013. http://hdl.handle.net/1969.1/151305.
Full textAbstract:
In this dissertation the ac-link universal power converters, which are a new class of power converters, are introduced and studied in detail. The inputs and outputs of these converters may be dc, ac, single phase, or multi-phase. Therefore, they can be used in a variety of applications, including photovoltaic power generation, wind power generation, and electric vehicles. In these converters the link current and voltage are both alternating and their frequency can be high, which leads to the elimination of the dc electrolytic capacitors and the bulky low-frequency transformers. Therefore, the ac-link universal power converters are expected to have higher reliability and smaller size. Moreover, these converters are soft switching, which results in negligible switching losses and minimized current and voltage stress over devices.
In the first part of the dissertation, the parallel ac-link universal power converter is studied in detail. This converter is an extension of the buck-boost converter. The series ac-link universal power converter, which is dual of the parallel ac-link universal power converter, is proposed in the second part of this dissertation. This converter is an extension of the Cuk converter. A modified configuration with fewer switches, named sparse ac-link universal power converter is proposed in the third part of this dissertation. The sparse ac-link universal power converters can appear as parallel or series.
The performance of all these configurations is evaluated through simulations and experiments.
43
Nyati, Sandeep. "Control of AC voltage of HVDC converter feeding into a weak AC system." 1988. http://hdl.handle.net/1993/16769.
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Li, Cheng-Chang, and 李承璋. "Study and Realization of a DSP-Based High-Performance AC/DC/AC Converter." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/19980591023974352170.
Full textAbstract:
碩士國立宜蘭大學
電機工程學系碩士班
97
A digital signal processor (DSP) -based high performance AC/DC/AC converter is studied and realized in this thesis, whose main contribution is the replacement of the former analog controller by digital system, which is trying to implement the simplicity, less interference noise and great reduction of system scale of the control circuit. Besides, the proposed digital controller can achieve the technique of average-current mode control and sinusoidal pulse width modulation (SPWM), which can retain the merit of high power factor and low input current harmonic, on the rectifier side, and the merit of stable AC output voltage and good dynamic regulation, on the inverter side, respectively. In this thesis, the function of soft-switching is derived through zero voltage switching (ZVS) strategy, namely, switching losses of main switch is lowered and higher efficiency is achieved. Finally, computer simulation and experimental results are presented in this thesis for verification.
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Liao, Di, and 廖荻. "Study and Implement of a Bi-Directional Bridgeless AC-Switch AC/DC Converter." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/f2n2zt.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
106
This thesis aims to study and design an output power 750 W, AC-side 230 V, DC-side 750 V bi-directional high efficiency and high power density for power converter of green energy system. For wider range of applications, this thesis implements synchronous rectification to achieve bi-directional power transference and the bridgeless topology for higher rectification-model efficiency, the inverter-model applied is a T-type inverter topology. On other the hand, the digital control used to replace analog control, the analog control is economical and simple but compared with digital control, it are some disadvantages such as not able to be using advance control technology and so on. Therefore, this thesis realize average current mode control for rectification-model and unipolar PWM control for invert-model base on digital signal processor. Finally, a high power density bi-directional converter has been achieved, the rectification-model efficiency about 98.11% and inverter-model efficiency around 96.2% in full-load.
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LinDean-Feng and 林鼎峰. "A novel DC/AC power converter system." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/55400784237530649325.
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碩士崑山科技大學
電機工程研究所
95
The cost of fossil energy was rsien up, recently. This has promoted the importance of the renewable energy. A small capacity DC/AC power conversion interface for renewable energy will be developed in this thesis. This power conversion interface including a DC/DC power converter and a DC/AC power converter. The PWM modualtion strategy is used in the DC/DC power converter to generate a rectifier sinusoidal current. The DC/AC inverter, opaerated in the low switching frequency, converts the the rectifier sinusoidal current to a sinuoidal current and feeds to the utility. Because the DC/AC inverter is opaerated in the low switching frequency, it can reduce the switching loss. Hence, the power efficiency of the entire system can be increased. Moreover, the DC capacitor between the DC/DC power converter and the DC/AC inverter can be omited.This can increase the reliability of the DC/AC power conversion interface. A prototype is developed and tested to demonstrate the performance of the proposed DC/AC power conversion interface. The experimental results show that the proposed DC/AC power conversion interface has the expected performance.
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Hong-WeiDeng and 鄧弘緯. "DSP Controlled AC-DC Bidirectional Power Converter." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/55249315633117041500.
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Wang, Sing-han, and 王星翰. "Robust Repetitive Control of DC/AC Converter." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/27477995344361845446.
Full textAbstract:
碩士國立中山大學
電機工程學系研究所
101
This thesis applies digital repetitive control to a single-phase DC-to-AC converter, with some proposed designs to improve stability and enhance performance of the converter under various load variations. A practical DC-to-AC converter is required to convert DC power to stable AC power with low harmonic distortion when attached to various linear or nonlinear loads. This thesis combines repetitive control with feedback dithering modulation and optimal state feedback to control the converter. The repetitive control is responsible for regulating output power and eliminating harmonics, while the feedback dithering modulation for switching the power transistors with reduced switching noise and the state feedback for stabilizing the converter under various load variations. The presented control and modulation schemes of the power converter are implemented on an FPGA (Field Programmable Gate Array). The experiments confirm the excellent performance and robustness of the converter, indicating a total harmonic distortion of less than 0.5% for the converter when attached to various linear or nonlinear loads.
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WU, XI-ZHEN, and 吳喜楨. "Interleaved DC-AC Converter With Decoupling Circuit." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/rhk4xt.
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碩士國立高雄科技大學
微電子工程系
107
DC-AC power converters have been widely used in solar power generation systems. This paper presents an interleaved DC-AC converter with a DC decoupling circuit. It consists of an interleaved DC-AC power converter and a decoupling circuit. The interleaved DC-AC power converter is controlled to convert the DC power to AC power and generate a sinusoidal current in phase with the utility voltage. The decoupling circuit is composed of two power electronic switches and passive filters. The decoupling circuit is used to decouple the DC component and double-frequency component, so as to suppress the double-frequency ripple of DC bus for the interleaved DC-AC power converter. Accordingly, the electrolytic capacitor can be replaced by a film capacitor to improve the reliability of solar power generation system. A DSP controlled prototype is developed and test to verify the performance of interleaved DC-AC converter with DC decoupling circuit.
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Liaw, Yisheu, and 廖怡咰. "Analysis and Design of Digital Signal Processor Applied to the AC/DC/AC Converter." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/45711160642468305694.
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碩士國立雲林科技大學
電機工程技術研究所
88
A current control technique based on the space vector modulation for a three-phase rectifier is adopted to the AC/DC/AC system. This control technique calculated the voltage in front of the switches of rectifier. Then by the space vector modulation, the rectifier can correct the power factor. The vector control method is used to construct the driving system of the induction motor. The optimal conduction time of the AC/DC/AC converter is achieved by the optimal voltage vector and time selector. Because the two converters are active in the same time, the power can be directly delivered to the three-phase induction motor. Thus instead of the bulky electrolytic capacitor in the dc link, small capacitors can be used. A quasi-parallel resonant DC link circuit can be applied to the induction motor system to implement the soft-switching inverter. In all signal processings, TI TMS320C240 digital signal processor is regarded as the heart of the system to complete the related software. From the results of experiments, it is proved that it can achieve the power factor correction and the stable AC/DC/AC operation even with the smaller capacitor.