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Faraci, William Eric. "Design of a Resonant Snubber Inverter for Photovoltaic Inverter Systems." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/47800.
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With the rise in demand for renewable energy sources, photovoltaics have become increasingly popular as a means of reducing household dependence on the utility grid for power. But solar panels generate dc electricity, a dc to ac inverter is required to allow the energy to be used by the existing ac electrical distribution. Traditional full bridge inverters are able to accomplish this, but they suffer from many problems such as low efficiency, large size, high cost, and generation of electrical noise, especially common mode noise. Efforts to solve these issues have resulted in improved solutions, but they do not eliminate all of the problems and even exaggerate some of them.
Soft switching inverters are able to achieve high efficiency by eliminating the switching losses of the power stage switches. Since this action requires additional components that are large and have additional losses associated with them, these topologies have traditionally been limited to higher power levels. The resonant snubber inverter is a soft switching topology that eliminates many of these problems by taking advantage of the bipolar switching action of the power stage switches. This allows for a significant size reduction in the additional parts and elimination of common mode noise, making it an ideal candidate for lower power levels. Previous attempts to implement the resonant snubber inverter have been hampered by low efficiency due to parasitics of the silicon devices used, but, with recent developments in new semiconductor technologies such as silicon carbide and gallium nitride, these problems can be minimized and possibly eliminated.
The goal of this thesis is to design and experimentally verify a design of a resonant snubber inverter that takes advantage of new semiconductor materials to improve efficiency while maintaining minimal additional, parts, simple control, and elimination of common mode noise. A 600 W prototype is built. The performance improvements over previous designs are verified and compared to alternative high efficiency solutions along with a novel control technique for the auxiliary resonant snubber. A standalone and grid tie controller are developed to verify that the auxiliary resonant snubber and new auxiliary control technique does not complicate the closed loop control.Master of Science
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Tang, Yuqing. "High Power Inverter EMI Characterization and Improvement by Auxiliary Resonant Snubber Inverter." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/31022.
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Electromagnetic interference (EMI) is a major concern in inverter motor drive systems. The sources of EMI have been commonly identified as high switching dv/dt and di/dt rates interacting with inverter parasitic components. The reduction of parasitic components relies on highly integrated circuit layout and packaging. This is the way to deal with noise path. On the other hand, switching dv/dt and di/dt can be potentially reduced by soft-switching techniques; thus the intensity of noise source is reduced.
In this paper, the relation between the dv/dt di/dt and the EMI generation are discussed. The EMI sources of a hard-switching single-phase PWM inverter are identified and measured with separation of common-mode and differential-mode noises. The noise reduction in an auxiliary resonant snubber inverter (RSI) is presented. The observation of voltage ringing and current ringing and the methods to suppress these ringing in the implementation of RSI are also discussed. The test condition and circuit layout are described as the basis of the study. And the experimental EMI spectra of both hard- and soft-switching inverter are compared. The effectiveness and limitation of the EMI reduction of the ZVT-RSI are also discussed and concluded.
The control interface circuit and gate driver design are described in the appendix. The implementation of variable charging time control of the resonant inductor current is also explained in the appendix.
Master of Science
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Saghaleini, Mahdi. "Switching Patterns and Steady-State Analysis of Grid-Connected and Stand-Alone Single-Stage Boost-Inverters for PV Applications." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/796.
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Renewable or sustainable energy (SE) sources have attracted the attention of many countries because the power generated is environmentally friendly, and the sources are not subject to the instability of price and availability. This dissertation presents new trends in the DC-AC converters (inverters) used in renewable energy sources, particularly for photovoltaic (PV) energy systems. A review of the existing technologies is performed for both single-phase and three-phase systems, and the pros and cons of the best candidates are investigated.
In many modern energy conversion systems, a DC voltage, which is provided from a SE source or energy storage device, must be boosted and converted to an AC voltage with a fixed amplitude and frequency. A novel switching pattern based on the concept of the conventional space-vector pulse-width-modulated (SVPWM) technique is developed for single-stage, boost-inverters using the topology of current source inverters (CSI). The six main switching states, and two zeros, with three switches conducting at any given instant in conventional SVPWM techniques are modified herein into three charging states and six discharging states with only two switches conducting at any given instant. The charging states are necessary in order to boost the DC input voltage. It is demonstrated that the CSI topology in conjunction with the developed switching pattern is capable of providing the required residential AC voltage from a low DC voltage of one PV panel at its rated power for both linear and nonlinear loads.
In a micro-grid, the active and reactive power control and consequently voltage regulation is one of the main requirements. Therefore, the capability of the single-stage boost-inverter in controlling the active power and providing the reactive power is investigated. It is demonstrated that the injected active and reactive power can be independently controlled through two modulation indices introduced in the proposed switching algorithm. The system is capable of injecting a desirable level of reactive power, while the maximum power point tracking (MPPT) dictates the desirable active power.
The developed switching pattern is experimentally verified through a laboratory scaled three-phase 200W boost-inverter for both grid-connected and stand-alone cases and the results are presented.
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Mansfield, Keith. "COMPARISON OF SINGLE STAGE AND TWO STAGE STAGE GRID-TIE INVERTERS." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2730.
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This thesis compares two methods of designing grid-tie inverters. The first design topology is a traditional two stage approach consisting of an isolated DC-DC converter on the input followed by a high switching frequency SPWM (Sinusoidal Pulse Width Modulation) stage to produce the required low frequency sine wave output. The novel second design approach employs a similar DC-DC input stage capable of being modulated to provide a rectified sine wave output voltage/current waveform. This stage is followed by a simple low frequency switched Unfolding Stage to recreate the required sine wave output. Both of the above designs have advantages and disadvantages depending on operating parameters. The following work will compare the Unfolding Output Stage and the SPWM Output Stage at various power levels and power densities. Input stage topologies are similarly examined in order to determine the best design approach for each output stage under consideration.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
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Larsen, Alexander, and Pontus Lindquist. "Forecasting mismatch losses: An empirical study investigating module level inverter- and string inverter systems." Thesis, KTH, Energiteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148089.
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The purpose of this thesis is to investigate the correlation between irradiance and power output for a system with a module level inverter and a string inverter, respectively. An empirical study has been conducted and inverters in photovoltaic systems will be discussed and divided into two types; module level and string inverters. Different sources of mismatch such as degradation, partial shading and manufacturing issues are also part of the study. The predicted mismatch for the string inverter system is 2,6 %, based on flash test data for fresh cells, although that value is likely to be underrated due to aging effects not accounted for in the model. The system equipped with module level inverters generated 6,1 % more energy during the measured period. Although the period of measuring is short and the number of systems compared is small, this study has identified multiple sources that explain why the string inverter system is inferior and is outperformed by the module level inverter system regarding power output.Syftet med detta arbete är att utforska korrelationen mellan solinstrålning och producerad effekt för två olika system. Det ena systemet består av lokala växelriktare och det andra av en strängomriktare. En empirisk studie har utförts och i detta arbete diskuteras växelriktare i fotovoltaiska system. Olika orsaker till varför förlorad effekt uppstår mellan modulerna så som ålder, skuggning och tillverkningsfel omfattas även av detta arbete. Det förutspådda värdet på effektförluster mellan modulerna i strängomriktarsystemet uppgick till 2,6 %, vilket är baserat på flash tester för nya solceller. Detta värde är troligtvis underskattat med tanke på att de celler som använts är föråldrade och att effekten av detta inte är medtaget i beräkningarna. Systemet med lokala växelriktare genererade 6,1 % mer elektricitet under den uppmätta perioden. Fastän den uppmätta perioden var kort och antalet system som studerades var litet så kunde flera faktorer identifieras som förklarar varför strängomriktare är underlägsna lokala växelriktare sett till producerad effekt.
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Krogemann, Markus. "The parallel resonant DC link inverter : a soft-switching inverter topology with PWM capability." Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/13526/.
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Soft-switching inverters have over the last decade received a lot of attention by researchers owing to the reduction or virtual elimination of switching losses that these circuits can achieve. Possible improvements in EMC performance due to the reduced levels of dv/dt have among other advantages triggered the development of a still growing number of zero-voltage or zero-current switching inverter circuits. More recently, the trend seems to have shifted from continuously resonant systems over to quasi-resonant topologies due to advantages in terms of device stresses and PWM compatibility. In this work, continuously resonant as well as quasi-resonant techniques are reviewed. A quasi-resonant circuit will be implemented in a three-phase PWM inverter system controlled by a network of transputers. It will be examined to which degree the working principle of this Parallel Resonant DC Link (PRDCL) inverter affects the PWM compatibility and a suitable PWM strategy will be presented and implemented. The modified PWM technique shows output quality comparable to standard PWM methods while being fully compatible with the operation of the resonant link. The conversion efficiency and EMC performance of a PWM inverter drive based on the PRDCL circuit will be measured and compared to its hard-switched equivalent. It will be shown that improvements over hard-switching inverters are possible. However, the investigation of the PRDCL PWM inverter also reveals a number of drawbacks which limit the achievable switching frequency and adversely affect the conversion efficiency. Despite the many previous publications these problems have generally been overlooked in the past.
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Breda, David Pedro. "Simulation of a resonant inverter." Master's thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/15931.
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Mestrado em Engenharia Electrónica e de TelecomunicaçõesMostly developed since the Industrial Revolution, the automation of systems and equipment around us is responsible for a technological progress and economic growth without precedents, but also by a relentless energy dependence. Currently, fossil fuels still tend to come as the main energy source, even in developed countries, due to the ease in its extraction and the mastery of the technology needed for its use. However, the perception of its ending availability, as well as the environmental impact of this practice has led to a growing energy production originated from renewable sources. Easy maintenance, coupled with the fact that they are virtually inexhaustible, makes the solar and wind energy very promising solutions. In this context, this work proposes to facilitate energy production from these sources. To this end, in this work the power inverter is studied, which is an equipment responsible for converting DC power available by solar or wind power in traditional AC power. Then it is discussed and designed a new architecture which, in addition to achieve a high energy e - ciency, has also the ability to adapt to the type of conversion desired by the user, namely if he wants to sell electricity to the power grid, be independent of it or bet on a self consumption system. In order to achieve the promised energy e ciency, the projected inverter uses a resonant DC-DC converter, whose architecture signi cantly decreases the energy dissipated in the conversion, allowing a higher power density. The adaptability of the equipment is provided by an adaptive control algorithm, responsible for assessing its behavior on every iteration and making the necessary changes to achieve maximum stability throughout the process. To evaluate the functioning of the proposed architecture, a simulation is presented using the PLECS simulation software.
Desenvolvida maioritariamente a partir da Revolução Industrial, a automatização dos sistemas e equipamentos que nos rodeiam e responsável por um progresso tecnológico e crescimento económico sem precedentes, mas também por uma incessante dependência energética. Atualmente, combustíveis fosseis ainda tendem a surgir com principal fonte de energia, mesmo em países desenvolvidos, devido a facilidade na sua extração e domínio da tecnologia necessária a sua utilização. No entanto, a perceção quer da sua findável disponibilidade, quer do impacto ambiental desta pratica, tem levado a uma crescente produção de energia proveniente de fontes renováveis. A sua fácil manutenção, aliada ao facto de serem praticamente inesgotáveis, faz das energias solar e eólica uma solução muito promissora. Neste contexto, esta dissertação propõe facilitar a produção de energia proveniente destas fontes. Assim, neste trabalho são estudados os inversores de potencia, equipamentos responsáveis por converter energia DC disponibilizada por uma fonte solar ou eólica em energia AC tradicional. Seguidamente e discutida e projetada uma nova arquitetura que, para al em de conseguir um alto rendimento energético, tem também a capacidade de se adaptar face ao tipo de conversão pretendida pelo utilizador, caso este queira vender energia a rede elétrica, ser independente desta ou apostar num sistema de auto consumo. Para alcançar o alto rendimento energético prometido, o inversor projetado faz uso de um conversor DC-DC ressonante, cuja arquitetura diminui consideravelmente a energia dissipada na conversão, permitindo assim uma maior densidade de potencia. A versatilidade do equipamento e disponibilizada por um algoritmo de controlo adaptativo, responsável por avaliar o comportamento deste a cada iteração e fazer as alterações necessárias para alcançar a máxima estabilidade ao longo de todo o processo. Para uma avaliação do funcionamento da arquitetura proposta, apresenta-se a simulação da mesma utilizando o software de simulação PLECS.
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Joel, Jaldemark. "Remote control of frequency inverter." Thesis, Högskolan i Halmstad, Akademin för informationsteknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-41400.
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Emotron has a frequency inverter on the market that different industries uses in their factories. In case of errors they need to send out service to the factories in order to examine the inverter and find the error. They now want a solution that makes it possible for them to give support without leaving the office by connecting their devices to the cloud which eliminates the need to send out staff to industries. Emotron gave this task to HMS and has been possible with their product Anybus wiress bolt. By connecting the Anybus wireless bolt to the inverter it was possible to communicate with the cloud, MicrosoftAzure, where a static webb application is hosted. The application is made to look like the terminal on the inverter and has similiar structures and functionality. Through the application users can communicate withthe inverter by means of controlling the connected motor, reading registers and also write to certain registers. These registers contain different measurement and option parameters. The purpose of this thesis was to create a Proof-of-Concept solution using the Anybus wireless bolt. The thesis has shown of industries can use Anybus wireless bolt and the tag engine to make it possible to create a link between machines and the ever- growing cloud and is also the first part of a bigger project.
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Chen, Baifeng. "High-efficiency Transformerless PV Inverter Circuits." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/56686.
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With worldwide growing demand for electric energy, there has been a great interest in exploring photovoltaic (PV) sources. For the PV generation system, the power converter is the most essential part for the efficiency and function performance. In recent years, there have been quite a few new transformerless PV inverters topologies, which eliminate the traditional line frequency transformers to achieve lower cost and higher efficiency, and maintain lower leakage current as well.
With an overview of the state-of-the-art transformerless PV inverters, a new inverter technology is summarized in the Chapter 2, which is named V-NPC inverter technology. Based this V-NPC technology, a family of high efficiency transformerless inverters are proposed and detailly analyzed. The experimental results demonstrate the validity of V-NPC technology and high performance of the transformerless inverters.
For the lower power level transformerless inverters, most of the innovative topologies try to use super junction metal oxide semiconductor field effect transistor(MOSFET) to boost efficiency, but these MOSFET based inverter topologies suffer from one or more of these drawbacks: MOSFET failure risk from body diode reverse recovery, increased conduction losses due to more devices, or low magnetics utilization. By splitting the conventional MOSFET based phase leg with an optimized inductor, Chapter 3 proposes a novel MOSFET based phase leg configuration to minimize these drawbacks. Based on the proposed phase leg configuration, a high efficiency single-phase MOSFET transformerless inverter is presented for the PV micro-inverter applications. The PWM modulation and circuit operation principle are then described. The common mode and differential mode voltage model is then presented and analyzed for circuit design. Experimental results of a 250 W hardware prototype are shown to demonstrate the merits of the proposed MOSFET based phase-le and the proposed transformerless inverter.
New codes require PV inverters to provide system regulation and service to improve the distribution system stabilization. One obvious impact on PV inverters is that they now need to have reactive power generation capability. The Chapter 4 improves the MOFET based transformerless inverter in the Chapter 3 and proposed a novel pulse width modulation (PWM) method for reactive power generation. The ground loop voltage of this inverter under the proposed PWM method is also derived with common mode and differential mode circuit analyses, which indicate that high-frequency voltage component can be minimized with symmetrical design of inductors. A 250-W inverter hardware prototype has been designed and fabricated. Steady state and transient operating conditions are tested to demonstrate the validity of improved inverter and proposed PWM method for reactive power generation, high efficiency of the inverter circuit, and the high-frequency-free ground loop voltage.
Besides the high efficiency inverter circuit, the grid connection function is also the essential part of the PV system. The Chapter 5 present the overall function blocks for a grid-connected PV inverter system. The current control and voltage control loop is then analyzed, modeled, and designed. The dynamic reactive power generation is also realized in the control system. The new PLL method for the grid frequency/voltage disturbance is also realized and demonstrate the validity of the detection and protection capability for the voltage/frequency disturbance.
At last, a brief conclusion is given in the Chapter 6 about each work. After that, future works on device packaging, system integration, innovation on inverter circuit, and standard compliance are discussed.Ph. D.
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Sirisukprasert, Siriroj. "Optimized Harmonic Stepped-Waveform for Multilevel Inverter." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35333.
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The concept of multilevel voltage source inverters and their modulation topologies are described. The concept of the Optimized Harmonic Stepped-Waveform (OHSW) technique for a multilevel inverter is presented. By applying this concept, specific harmonics can be eliminated, and the output voltage THD can be improved. A procedure to achieve the appropriate switching angles of the OHSW is proposed. Experimental results are presented to verify the concept. The proposed OHSW technique is implemented on a multilevel inverter using cascaded-inverter with separated dc sources. Comparison between the Selective Harmonic Eliminated PWM and the OHSW is also presented.Master of Science
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Rondelli, Luca. "Inverter in GaN per applicazioni automotive." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18652/.
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Questo elaborato si concentra sul progetto di un inverter trifase per applicazione automotive, basato su transistor a GaN. In particolare, si vuole studiare e dimostrare l'elevata efficienza energetica di questa tecnologia di transistor, che si traduce con un elevato rendimento di un inverter per il pilotaggio di un motore elettrico per trazione.
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Ahmed, M. M. "Modelling of inverter-fed induction machine." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234246.
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Molepo, Seaga Abram. "A multilevel inverter for DC reticulation." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53253.
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Thesis (MScEng)--Stellenbosch University, 2003.ENGLISH ABSTRACT: This report presents the design and development of a multilevel inverter for DC reticulation. Two main multilevel inverter topologies are introduced and discussed. The research focusses on the flying capacitor multilevel topology, since it became evident that it is more suitable for DC reticulation than the diode clamped multilevel topology. A bootstrap power supply for the gate drive circuits of a multilevel inverter is developed and its feasibility verified experimentally. A self-starting auxiliary power supply, that aims at addressing the power supply problem of DC to AC and DC to DC converters, is designed and its functionality demonstrated on a flying capacitor multilevel inverter. An FPGA based digital controller for implementing the inverter's control algorithms is also discussed. This controller incorporates a feed-forward output voltage regulation technique. Experimental results obtained with the four-level flying capacitor multilevel inverter, using the FPGA based digital controller and the self-starting auxiliary power supply, are presented in this report.
AFRIKAANSE OPSOMMING: In hierdie verslag word die ontwerp en ontwikkelling van 'n multivlak omsetter vir GS retikulasie bespreek. Twee hoof multivlak omsetter topologië word voorgestel en bespreek. Die navorsing fokus op die "vlieënde-kapasitor" multivlak topologië omdat dit duidelik geword het dat dit 'n beter opsie is vir die GS retikulasie as die diode-klamp multivlak topologië. 'n Kragbron vir die hekaandryfbane van die multivlak omsetter is ontwikkel en die werking daarvan is met experimentele toetse bevestig. 'n Self-begin kragbron, wat die probleem van die kragtoevoer aan die GS na WS en die GS na GS omsetters aanspreek, is ontwerp en die funksionaliteit is gedemonstreer met die "vlieënde-kapasitor" multivlak . omsetter. 'n Digitale beheerder, gebaseer op 'n FPGA, wat gebruik word om die omsetter se beheer algoritmes te implementeer, word ook bespreek. Hierdie beheerder inkorporeer 'n vorentoe-voer uittree spannings regulasie tegniek. Eksperimentele resultate wat gekry is met 'n vier-vlak "vlieënde-kapasitor" multivlak omsetter, wat van die FPGA gebaseerde digitale beheerder en die self-begin kragbron gebruik maak, word ook in die verslag bespreek.
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Esuri, Abdulhamid H. "Two-phase inverter/induction motor drive." Thesis, Loughborough University, 1991. https://dspace.lboro.ac.uk/2134/33109.
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Much interest is shown nowadays in the use of variable-speed ac motor drives in applications which previously have been the domain of the de motor supplied from a controlled rectifier or chopper. This interest is due mainly to improvements in semiconductor switching technology and the consequent increased reliability of the de-link inverter, together with the cost-effectiveness and the long-term reliability of ac machines, especially squirrel-cage induction motors. This thesis presents a recently developed form of variable-speed ac motor drive, comprising a 2-phase induction motor fed by a 2-phase inverter. A detailed mathematical model for the drive is developed and this is used to predict the dynamic and steady-state performance of a 300W experimental arrangement under various operating conditions and for both square-wave and sinusoidal PWM modes of operation. The validity and accuracy of the model are confirmed by the close agreement obtained in both shape and value between the experimental and predicted results. The harmonic content of the drive waveforms and the levels of torque and speed pulsations resulting from the inverter supply for both the square-wave and PWM modes of operation are evaluated, and the effects of load-torque and operating frequency variations on the drive performance are also considered. It is concluded in the thesis that this drive arrangement offers the advantages of relative simplicity, high reliability and little maintenance, and can provide a reasonably good performance and efficiency over a wide speed range. Consequently, it is a viable alternative for many variable-speed drive applications.
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Chang, Chin-Yao. "Hierarchical Control of Inverter-Based Microgrids." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471815065.
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Smith, Wayne Anthony. "Commissioning a 400 Hz rotary inverter." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/9226.
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Includes bibliographical references (leaves 113-115).This dissertation covers the commissioning and testing of an aircraft's constant frequency alternator as the power supply for the Blue Parrot radar. The Blue Parrot is an X-band radar which forms part of the navigation and weapon-aiming system onboard the Buccaneer S-50 SAAF aircraft. The radar set uses a source of three-phase power at 400 Hz, which the constant frequency alternator can supply with the aid of certain auxiliary systems. The auxiliary systems include a prime mover, blower fan and a telemetering system. The prime mover has high starting currents which were reduced significantly by the use of a soft-starter. During testing, the constant frequency alternator started overheating and a blower fan was selected based on its thermal requirements. Significant cooling of the constant frequency alternator's case temperature was achieved by the use of a blower fan and shroud. The generator control unit monitors and regulates all parameters on the unit except for case temperature and blower fan pressure. A telemetering system was designed and built to monitor and display these parameters.
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Lindstén, Johanna. "Frequency Response from Inverter-Based Generation." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287453.
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The system inertia of the Nordic power system is expected decrease in the future. This is due to an expected reduction in synchronous generation from nuclear and thermal power. This will be compensated by an increase in power from inverter-based generation due to wind power’s expansion in the power system. In this thesis, a power system’s ability to handle a large under-frequency fault is studied and how this is affected by a lower system inertia. The thesis also studies how different types of frequency response from wind power plants affects the systems ability to handle the fault. The frequency of a modelled transmission system is studied through dynamic simulations in the software PSS/E. Changes are made to the system to replace nuclear power (and eventually also thermal power) with type 4 (full-sized converter) wind turbines. A large under-frequency event is induced and the frequency nadir and bus voltages are compared against system limits used by the Swedish TSO. While gradually adding wind power to the system as nuclear power is removed, different versions of the system with different amounts of wind power are compared. Two studies are carried out. In the first study, the voltage response study, nuclear power is decreased by scaling down the size of the generators. Besides reducing their power output and inertia, this also decreases their capacity for voltage support. To compensate for the reduced voltage support in the system, the wind power plants are made to provide voltage support. In the second study, the inertia study, the nuclear power in the system is instead decreased by reducing the active power output and the inertia constant of the nuclear generator. The size of the generator and reactive power output stay the same as in the original system so the nuclear power plant can continue to supply voltage support. In this way the problems caused by reduced inertia in the system are isolated. In both studies, three different frequency responses are applied to the wind power plants. The three frequency responses are aimed to as closely as possible follow the minimum requirements from the Swedish TSO for the frequency response products FCR-N, FCR-D and FFR alt A. In both studies, FCR-N provided by wind power causes a lower the system frequency during the fault compared to the original system without wind power. FCR-N can not fully compensate for the loss of inertia the replacement of synchronous generation is causing. In the voltage response study, FCR-D causes a slightly lower system frequency than the original system without wind. In the inertia study the frequency is slightly raised with wind power providing FCR-D. In both studies, FCR-D is or is very close to fully compensating for the loss of inertia. In both studies with FFR alt A, more wind power and therefor more FFR alt A in the system means a significantly improved frequency nadir. One conclusion from this project is that both FCR-D and FFR alt A from wind power are effective at counter-acting the effects reduced system inertia has on the system frequency stability in this system. For both FCR-D and FFR alt A, the frequency deviation during the fault is lower or close to equal to the frequency deviation when the original system (no wind power) is subjected to the same fault. The second conclusion is that in the studied system the reduced capacity of voltage support due to removal of nuclear power in the system is more influential than the reduced system inertia in the expansion of wind power. This indicates that there may need to be more focus from power producers, TSOs and legislators on voltage support in the future as the power system moves from large synchronous power plants to more distributed inverter-based production.Det nordiska elkraftsystemets systemtröghet förväntas minska i framtiden. Detta beror på minskad synkroniserad kraftproduktion från kärnkraft och värmekraft som väntas ersättas av ökad kraftproduktion från inverterar-baserad kraftgenerering där vindkraft står för en stor del av ökningen. I detta examensarbete studeras ett kraftsystems förmåga att hantera en större störning och hur detta påverkas av minskad systemtröghet. Examensarbetet jämför också hur olika typer av frekvensreglering från vindkraft påverkar systemets förmåga att hantera störningen. Systemfrekvensen av ett modellerat transmissionssystem studeras genom dynamiska simuleringar i PSS/E. Ändringar görs till systemet för att byta ut produktion från kärnkraft (och så småningom också värmekraft) med icke-synkrona vindkraftsturbiner. En större störning induceras och systemets frekvens och nodspänningar jämförs med systemgränser som används av den svenska systemansvariga. Genom att gradvis addera vindkraft till systemet och ta bort kärnkraft, skapas olika versioner av systemet med olika andelar produktion från vindkraft som sedan jämförs. Två studier genomförs. I den första studien minskas kärnkraften i systemet genom att skala ned storleken på kärnkraftsgeneratorerna. Förutom att reducera deras aktiva och reaktiva kraftproduktion så sänker detta också deras kapacitet för spänningsreglering vilket skapar problem med låga spänningar. För att kompensera för den minskade spänningsregleringen så förses vindkraften i systemet med spänningsreglering. I den andra studien minskas mängden kärnkraft i systemet genom att minska dess aktiva kraftproduktion och tröghetskonstant. Storleken på generatorerna och deras reaktiva kraftproduktion ändras inte vilket gör att kärnkraftsgeneratorerna kan fortsätta bidra med spänningsreglering. På detta sätt isoleras problemen som minskad systemtröghet ger upphov till. I båda studier appliceras tre olika frekvensregleringstyper på vindkraftverken i systemet. De tre frekvensregleringarna är ämnade att så nära som möjligt följa de tekniska kraven från den svenska systemansvarige för frekvensregleringsprodukterna FCR-N, FCR-D och FFR alt A. FCRN från vindkraft ger i båda studier upphov till en lägre systemfrekvens under felet jämfört med det ursprungliga systemet utan vindkraft. Detta betyder att FCR-N inte fullt kompenserar för den reducerade systemtrögheten orsakad av minskad mängd kärnkraft i systemet. FCR-D ger upphov till något lägre frekvens i den första studien och något högre frekvens in den andra studien jämfört med ett system utan vindkraft. FFR alt A leder i båda studier till en betydligt förbättrad frekvens jämfört med det ursprungliga systemet utan vindkraft. En slutsats från detta arbete är att både FCR-D och FFR alt A från vindkraft är effektiva i att motarbeta effekterna som en sänkt systemtröghet har på detta systems frekvensstabilitet. I båda fall är frekvensavvikelsen under störningen lägre eller nära samma som i originalsystemet utan vindkraft när de utsätts för samma störning. Den andra slutsatsen är att i detta är system är förlusten av spänningsreglering, som kärn- och värmekraften bidrog med, mer begränsande för mängden vindkraft som kan introduceras än vad sänkningen av systemtröghet var. Detta indikerar att det kan behövas mer fokus på spänningsreglering från kraftproducenter, systemansvariga och lagstiftare i framtiden när kraftsystemet rör sig från större synkroniserade kraftverk till mer distribuerad inverterar-baserad kraftproduktion.
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Liu, Xiao. "IMPROVEMENTS IN INVERTER MODELING AND CONTROL." UKnowledge, 2017. http://uknowledge.uky.edu/ece_etds/104.
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In this dissertation, the generalized averaging method models for inverters, reactive power control methods for photovoltaic inverters, and a noise immunity improvement for hybrid position observers for brushless dc motor drives are studied.
Models of inverters and other converters based on averaging have been widely used in numerous simulation applications. Generalized averaging can be applied to model both average and switching behavior of converters while retaining the faster run times associated with average-value models. Herein, generalized average models for single- and three-phase pulse width modulation inverters are proposed. The modulation signal for the proposed model could be either a sinusoidal waveform without high order harmonics or a sinusoidal waveform with third-harmonic injection. And this generalized average models also can apply for modeling three-phase pulse width modulation inverters with varying modulation signal frequency in the reference frame. These models are based on a quasi-Fourier series representation of the switching functions that includes fundamental and switching frequency components as well as sideband components of the switching frequency. The proposed models are demonstrated both in simulation and experimentally and are found to accurately portray both the fundamental and the switching behavior of the inverter. In particular, the use of sideband components allows accurate representation of the variation in switching ripple magnitude that occurs in the steady state. The generalized average models are found to have simulation run times that are significantly faster than those associated with detailed models. Therefore, the proposed generalized average models are suitable for simulation applications in which both accuracy (including the switching behavior) and fast run times are required (e.g., long simulation times, systems with multiple converters, and repeated simulations).
Variations in the output power of intermittent renewable sources can cause significant fluctuations of distribution system voltage magnitudes. Reactive power control methods that employ the reactive power capability of photovoltaic three-phase inverters to mitigate these fluctuations are proposed. These control methods cause the three-phase inverters to substitute reactive output power for real output power when fluctuations in the solar power are experienced, allowing the fluctuations to be controlled. Performance metrics for assessing the ability of these controllers to perform this mitigation are defined. The controllers are examined using the IEEE 123-bus feeder distribution system, and it is found that the controllers can effectively mitigate voltage magnitude fluctuations and that the appropriate choice of controller depends on the performance metrics of interest.
Finally, a noise immunity improvement for hybrid position observers for brushless dc motor drives is proposed. A finite state machine is used to detect Hall-effect sensor transitions to determine if these transitions are true transitions or the result of momentary glitches. This filter causes a delay in the detection of the Hall-effect sensors that is compensated in the proposed observer. The proposed observer is compared in simulations with the original hybrid position observer under both non-noisy and noisy conditions for both constant and variable speed operation, and it has good performance even under high noise and variable speed conditions.
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Moghadam, Mansour Salehi. "Current-source-based low frequency inverter topology." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/12750.
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A DC to AC inverter can be classified in different topologies; some of these topologies are three level and multilevel inverter. Both types have some advantages and disadvantages. Three level inverters can be applied for low power applications because it is cheaper and has less semiconductor losses at high switching frequencies with poor total harmonic distortion (THD). Multilevel inverters (MLI) can be applied for higher power applications with less THD. However, the MLI has more cost and conductive power losses in comparison with three level inverters. In order to overcome the limitations of three and multilevel topologies, this thesis presents a new controlling topology of multilevel DC/AC inverters. The proposed multilevel inverter topology is based on a current source inverter, which consists of a buck/boost, boost and flyback converters, and an H-bridge inverter. The output voltage of the inverter is shaped through the control of just one main semiconductor switch. This new topology offers almost step-less output voltage without the need for multi DC source or several capacitor banks as in the case of other multilevel inverter topologies. The efficiency of the proposed topology is higher than other inverter topologies for medium power applications (2-10 kW). The proposed topology also generates smaller Total Harmonic Distortion (THD) compared to other inverter topologies. The two main key aspects of the proposed circuit is to keep the switching losses as low as possible and this is achieved through the control of a single switch at relatively low frequency and also to generate an improved AC Voltage waveform without the need for any filtering devices. The output frequency and voltage of the proposed circuit can be easily controlled according to the load requirements. The proposed inverter topology is ideal for the connection of renewable energy; this is due to its flexibility in varying its output voltage without the need of fixed turns-ratio transformers used in existing DC/AC inverter topologies. The harmonic contents of the output of this proposed topology can be controlled without the need of any filter. The simulation and practical implementation of the proposed circuits are presented. The practical and simulation results show excellent correlation.
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Kadhim, Ammar Hadi. "Control of an inverter driven reluctance motor." Thesis, University of Bradford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281134.
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Carpenter, Michael John. "Circuit representation of inverter-fed synchronous motors." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/46987.
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Kong, Fei. "Development of series connected photovoltaic power inverter." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609938.
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Bittencourt, Marcelo Corrêa de. "Comparing different and inverter graph data structure." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/185987.
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Este documento apresenta uma análise de desempenho de quatro diferentes implementações de And-Inverter Graph (AIG). AIGs são estruturas de dados normalmente utilizadas em programas que são utilizados para design de circuitos digitais. Diferentes implementações da mesma estrutura de dados pode afetar o desempenho. Isto é demonstrado em trabalhos anteriores que avaliam o desempenho de diferentes pacotes BDD (Binary Decision Diagram), que é outra estrutura de dados largamente utilizada em síntese lógica. Foram implementadas quatro estruturas de dados diferentes utilizando grafos unidirecionais ou bidirecionais aos quais os nodos são referenciados utilizando ponteiros ou índices de inteiros não-negativos. Utilizando estas diferentes estruturas de dados de AIG, medimos como diferentes aspectos das implementações afetam o desempenho da execução de um algoritmo básico.This document presents a performance analysis of four different And-Inverter Graph (AIG) implementations. AIG is a data structure commonly used in programs used for digital circuits design. Different implementations of the same data structure can affect performance. This is demonstrated by previous works that evaluate performance for different Binary Decision Diagram (BDD) packages, another data structure widely used in logic synthesis. We have implemented four distinct AIG data structures using a choice of unidirectional or bidirectional graphs in which the references to nodes are made using pointers or indexed using non-negative integers. Using these different AIG data structures, we measure how different implementation aspects affect performance in running basic algorithm.
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VALLURUPALLI, VAISHALI. "AGENT BASED MODELING OF A BIO-INVERTER." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1172264092.
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Kleyn, D. A. "3-Phase gate-turn off thyristor inverter." Master's thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/21866.
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Bibliography: 140-146.The requirements of a standard 3-phase Induction Motor driven by a Voltage Source Inverter (VSI) are studied. A full 3-phase Variable Speed Drive (VSD) and its controller have been designed, constructed and tested. Gate Turn-Off Thyristors (GTO's) are used as the main switching elements in the Inverter stage of the Drive. The drive requirements of GTO's are studied in detail.
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Plet, Cornelis Arie. "Fault response of inverter-based distributed generation." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9537.
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The work presented in this thesis focuses on developing and experimentally verifying accurate analytical equivalent models of inverters during short-circuit conditions for use in numerical fault studies. In addition, a concept design for a variable speed generator that does not contribute to the local fault level is presented and verified by simulation and experiment. The flexibility of control offered by the application of power electronics in distribution networks is paramount in the transition to a decentralised power system but still faces significant technical challenges to widespread integration into the incumbent utility grid. Power electronic interfaces have historically only been used in rare cases and their effect on the network has hitherto often been ignored. The uptake of energy sources such as photovoltaics, variable speed wind, fuel cells, microturbines has caused a sufficient increase in grid connection requests for inverter interfaced generators, that before long their fault behaviour can no longer be neglected. The fault response of an inverter is dictated by its control strategy, its current limiting strategy and the reference frame in which they have been implemented. Current limiting typically breaks an inverter’s outer control loop and effectively turns it into a current source. Depending on the exact method of current limiting, linear analytical equivalent models have been developed whose source and impedance values can be expressed as a function of the inverters hardware parameters and controller gains evaluated at the fundamental frequency. The resulting models are compatible with conventional network analysis techniques and have been verified by comparing the results of such an analysis with experimental results. Fault models have been developed for stand-alone and grid-connected inverters. In congested networks the connection of an additional generator can cause the substation circuit breaker ratings to be exceeded. A full inverter interface can be controlled not to contribute to the fault current but is still prohibitively expensive at higher power levels. An alternative generator based on a doubly-fed induction generator is proposed and experimentally tested. By inserting a tap in the rotor winding, the voltage-per-turn can temporarily be increased to retain control of the quickly rising fault current without having to upgrade the machine-side inverter’s ratings. A fast thyristor-based tap changer inverter is proposed and experimentally verified that performs the pulse width modulation and diverts the modulated waveform to the desired tap on the rotor winding. The tap changer can be commutated in such a way as to achieve the fastest possible rate of current transfer during a tap change whilst avoiding voltage spikes by allowing any energy stored in the rotor leakage inductance to return to the DC-link. The developed fault models and zero fault current generator are a step towards familiarising utility engineers with power electronics and how they affect the operation of the distribution network. The availability of standardised models avoids the need for expensive and time-consuming time domain simulation based fault studies for inverter connection requests. The work presented in this thesis may act as a base for the development of standardised representations of power electronics in power networks.
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Chaing, Chia-Tsung. "Five-level inverter employing WRPWM switching scheme." Diss., University of Pretoria, 2005. http://upetd.up.ac.za/thesis/available/etd-07102008-081413/.
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Medina, Alfredo. "Low-Frequency Series Loaded Resonant Inverter Characterization." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1620.
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Modern power systems require multiple conversions between DC and AC to deliver power from renewable energy sources. Recent growth in DC loads result in increased system costs and reduced efficiency, due to redundant conversions. Advances in DC microgrid systems demonstrate superior performance by reducing conversion stages. The literature reveals practical DC microgrid systems composed of wind and solar power to replace existing fossil fuel technologies for residential consumers. Although higher efficiencies are achieved, some household appliances require AC power; thus, the need for highly efficient DC to AC converters is imperative in establishing DC microgrid systems. Resonant inverter topologies exhibit zero current switching (ZCS); hence, eliminate switching losses leading to higher efficiencies in comparison to hard switched topologies.
Resonant inverters suffer severe limitations mainly attributed to a load dependent resonant frequency. Recent advancements in power electronics propose an electronically tunable inductor suited for low frequency applications [24], [25]; as a consequence, frequency stability in resonant inverters is achievable within a limited load range. This thesis characterizes the operational characteristics of a low-frequency series loaded resonant inverter using a manually tunable inductor to achieve frequency stability and determine feasibility of utilization. Simulation and hardware results demonstrate elimination of switching losses via ZCS; however, significant losses are observed in the resonant inductor which compromises overall system efficiency. Additionally, harmonic distortion severely impacts output power quality and limits practical applications.
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Huang, Po-Hsu. "Systematic control strategy for inverter-based microgrids." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121612.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 121-125).
Small-scale power systems, microgrids (MGs), are becoming economically and technically feasible due to cost-effective battery storage with high-bandwidth inverter interfaces, thus facilitating efficient energy utilization from renewable sources to maintain autonomous operation without a grid connection. Therefore, control of inverter-based or inverter-dominant systems is gaining a lot of attention while posing different challenges compared to traditional power systems. Conventional droop-based control architectures can provide power-sharing capability, and are considered to be a cost-effective and reliable solution for microgrids. However, experimental studies have revealed that for small-scale microgrids, stability is significantly compromised by the droop control due to low X/R ratios and short lines. Therefore, a proper modeling framework for obtaining concise and accurate models becomes important to understand the physical nature of the instability. Such a framework can further facilitate a systematic control design for stability enhancement, allowing the development of power-sharing strategies and plug-and-play functionality for efficient microgrid operation. In this thesis, high-fidelity reduced-order models for microgrids are first developed and investigated. Then, based on the proposed models, concise and simple stability certificates are derived along with virtual impedance methods for local and global stability enhancement. Detailed discussions are carried out on the control design that aims at achieving both droop stability and controller robustness. Finally, a power and energy management scheme based on secondary compensation is developed to enhance operational efficiency. The integrated solution provides a comprehensive reference for the development of stable, reliable, and flexible inverter-based microgrids. All results are validated through both simulation and experimental studies.
by Po-Hsu Huang.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Braun, Weston D. "A high frequency variable load inverter architecture." Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/121623.
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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 163-165).
This thesis presents a high frequency variable load inverter architecture along with a physical prototype and eciency optimizing controller. The inverter architecture consists of two constituent inverters, one connected directly through the load and the other connected through an immittance converter, which acts as a lossless power combiner. By controlling the amplitude and relative phase of the two constituent inverters the loading seen by each constituent inverter can be kept in a desirable range for wide variations in load impedance. This allows for the use of highly ecient zero voltage switching inverters that would otherwise be precluded in applications with widely varying load impedances, such as wireless power transfer and plasma generation. Previous solutions to the challenge of driving widely variable load impedances, such as the tunable matching network, have typically resulted in systems that are often bulky, expensive, and slow. The physical prototype developed for this project operates at 13.56MHz and can supply a maximum output power of 1kW into a 21:8 + 0:3j load at an eciency of 95:4%. The eciency optimizing controller utilizes a quasi-static model prediction approach which allows for optimization of system performance over any desirable parameter. The system is also capable of driving a wide range of capacitive and inductive loads at a high power level and with high efficiency.
by Weston D. Braun.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Wang, Jen-Ju, and 王仁裕. "General Digital Inverter." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/68768530067091156184.
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碩士國立中山大學
電機工程學系研究所
89
Abstract: This paper designs and implements a DSP-microprocessor based motor driver. We control the induction motor with V/F scheme. And we module all circuits with PCB Layout.This Inverter is compose of digital board and analog-power board. We connect two parts, and we use a three phase induction motorto to be the load. Because the digital board is compose of DSP, it is to fit a lot of mathematics. It is easy to use the software to present the theory. So the paper compute the three phase gate signals with asymmetrical Pulse-Width-Modulation model.
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Chen, Hung-tien, and 陳洪典. "Fully-Digitized Inverter." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/00320624440786105869.
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碩士國立臺灣科技大學
電子工程系
97
This thesis develops an inverter for recreational vehicles and compares the differences between two digital controllers. A front-stage push-pull converter boosts the lead-acid batteries voltage (12 V) to 200 V. Then a post-stage single-phase full-bridge inverter converts the 200-V input voltage to an AC output voltage with an amplitude of 110 V to 120 V and a frequency of 60 Hz, to supply the electrical equipment in recreational vehicles. This thesis also introduces the operation principles and structure of the converter system, including the push-pull converter, the single-phase full-bridge inverter, the sinusoidal pulse width modulation technology, and the analysis and design of the feedback compensator, the digital controllers and the protection circuits. A prototype inverter is built and tested with a 16-bit digital signal processor and an 8-bit microcontroller, respectively. Experimental results verify the correctness and feasibility of the presented inverter system.
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Hegde, Shweta. "Solar Micro Inverter." Thesis, 2014. http://hdl.handle.net/1805/5914.
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Indiana University-Purdue University Indianapolis (IUPUI)The existing topologies of solar micro inverter use a number of stages before the DC input voltage can be converted to AC output voltage. These stages may contain one or more power converters. It may also contain a diode rectifier, transformer and filter. The number of active and passive components is very high. In this thesis, the design of a new solar micro inverter is proposed. This new micro inverter consists of a new single switch inverter which is obtained by modifying the already existing single ended primary inductor (SEPIC) DC-DC converter. This new inverter is capable of generating pure sinusoidal waveform from DC input voltage. The design and operation of the new inverter are studied in detail. This new inverter works with a controller to produce any kind of output waveform. The inverter is found to have four different modes of operation. The new inverter is modeled using state space averaging. The system is a fourth order system which is non-linear due to the inherent switching involved in the circuit. The system is linearized around an operating point to study the system as a linear system. The control to output transfer function of the inverter is found to be non-minimum phase. The transfer functions are studied using root locus. From the control perspective, the presence of right half zero makes the design of the controller structure complicated. The PV cell is modeled using the cell equations in MATLAB. A maximum power point tracking (MPPT) technique is implemented to make sure the output power of the PV cell is always maximum which allows full utilization of the power from the PV cell. The perturb and observe (P&O) algorithm is the simplest and is used here. The use of this new inverter eliminates the various stages involved in the conventional solar micro inverter. Simulation and experimental results carried out on the setup validate the proposed structure of inverter.
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Fang, Chun-Chieh, and 方俊傑. "High Efficiency Power Inverter." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/29292522298689399954.
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碩士國立臺南大學
綠色能源學科技學系碩士在職專班
103
This paper focuses on the study of high-frequency DC to AC converter with high power conversion. The converter is divided into two parts. The first part realizes DC/DC boost conversion; the DC input voltage of battery is boosted to high voltage DC by virtue of push-pull type conversion architecture, while the open circuit of DC boost circuit is not subject to voltage stabilization feedback control. The second part realizes DC/AC full-bridge conversion; the high-voltage DC is converted into AC output, and the size of DUTY for the full-bridge architecture switch should be adjusted according to the required AC voltage, frequency and the degree of user's open load, in order to achieve the standard specifications for simulation of city electricity. The voltage boost part does not adopt voltage stabilization feedback control. With the fluctuation in the level of input voltage and the load, the low efficiency of power converter used during charging can be enhanced. Compared with the machine of traditional voltage stabilization feedback, there is about 5-10% of the power loss to be saved in the overall conversion efficiency. This part will be compared with the actual loading by another same model of machine featuring DC/DC voltage stabilization feedback control, thereby gaining the results and being confirmed.
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Kang, JIN-JIA, and 康晉嘉. "Analysis of Inverter Mechanism." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/kqjurs.
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碩士國立宜蘭大學
機械與機電工程學系碩士班
107
This paper discusses the form and the mechanism design of the inverter. The research process is : Understand the considerations and regulations of inverter design, how to implement application in different workplace. Then discuss how environmental factors influence the design of the inverter mechanism, the relationship between structural strength and different material selection, and how does production cost, processing and precision affect the structure? This paper establishes the component models of inverters on market, and uses ANSYS finite elements to analyze its structural strength, then measuring the displacement and acceleration of the components under given load created by a vibration platform exciter to verify the accuracy of the simulation. Finally, this paper compares different national standards and assess whether meets the requirements or not, and establishes a design procedure and guidelines for construction of inverter.
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Tai, Yu-Kun, and 戴佑坤. "Isolated DC-AC Inverter." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/e3bb6w.
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碩士國立臺北科技大學
電機工程系研究所
96
An isolated DC-AC inverter is presented herein. There are two stages in this inverter. The first stage is the DC-DC converter whereas the second stage is the DC-AC converter. Most of all, a novel cascaded pulse-width-modulated (PWM) DC-DC controller is applied to the first stage. As for the control of the second stage, a high performance digital controller named as dsPIC30F4011 is used to create the sinusoidal PWM (SPWM) control signal for the inverter so as to transfer the DC voltage to the AC voltage. In this thesis, first of all, the theoretical derivation is introduced, and secondly some simulated and experimental results are provided to verify the effectiveness of the proposed control strategy.
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SHYU, F. S., and 徐福三. "Implementation of Multilevel Inverter System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/90485116661531334882.
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碩士國立臺北科技大學
電機工程系碩士班
89
The details of implementation and analysis of pulse-width modulation techniques for a multilevel inverter system will be presented in this thesis. Since conventional two-level inverter has a limitation regarding output, multilevel inverter is used to cope with this issue. It has been demonstrated that the so-called cascaded multilevel inverter is superior to other multilevel approaches. In this thesis, an experimental system is implemented, which consists of a Digital Signal Processor (DSP), interface circuit, protection circuit and driving circuit, and thereby driving the multilevel inverter. Moreover, the so-called programmed harmonic elimination technique is used since the technique provides optimal harmonic elimination while using less number of commutations. This technique is realized using DSP assembly language and thereby generating the signals for multilevel inverter control. Experimental and simulation results confirm the theoretical analysis and its validity.
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Lin, Po-Chen, and 林柏丞. "Phase Controlled Piezoelectric Backlight Inverter." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/37450927513584298539.
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碩士國立臺灣大學
電子工程學研究所
93
The backlight system is one of the most important parts in the liquid crystal display (LCD) TV. It consumes most of the power of the whole TV system. Furthermore, the power dissipated by the backlight system increases as the size of the LCD increases. To achieve higher power efficiency, piezoelectric transformers are utilized in the backlight systems. A piezoelectric transformer can be a high-efficiency power converter. Compared with a traditional electromagnetic transformer, it has many advantages such as higher safety, lower electromagnetic interference (EMI) and smaller volume. However, a piezoelectric transformer has the highest efficiency and the highest voltage gain only when it is operated around its resonant frequency. As a result, it is very important to maintain the operating frequency of a piezoelectric transformer. This thesis is focused on the application of the piezoelectric transformer in the LCD TV backlight system. The relations between the phase difference of the input voltage and the output current, operating frequency, and voltage gain are discussed. A phase control strategy is also proposed. The control strategy uses the phase of the output current as the feedback signal to maintain the operating frequency of the piezoelectric transformer. We implement the designed phase controlled circuit with piezoelectric transformer to ignite the CCFL and the EEFL.
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Huang, Hong-Xun, and 黃鴻勳. "Design of Piezoelectrical Inverter Actuator." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/86670556214759078512.
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碩士中原大學
機械工程研究所
95
Abstract The design of driving circuitry for a Rosen-type piezoelectric transformer for cold-cathode fluorescent lamp (CCFL) is studied in this article. By using piezoelectric transformer with the merits of high voltage start-up ratio and high efficiency of energy transmission, the disadvantages of low transmission efficiency and slow heat dissipation rate and EMI due to high turn ratio of the traditional electromagnetic transformer is thus improved. The driving circuitry is fundamentally designed with the half-bridge inverter. By using the PWM control, the half-bridge inverter of zero-voltage switching (ZVS) is achieved so that it can obtain soft switching to reduce the loss of power switch. Also, a frequency-modulation alternate current square signal is generated through a resonance circuit constructed with an inductance and a capacitor of the piezoelectric transformer. Experiments on a 7-inch and 15-inch CCFL are carried out to verify the performance of the driving circuitry. Keywords: cold-cathode fluorescent lamp (CCFL), piezoelectric transformer
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Wang, Bo-Han, and 王柏翰. "Harmonic Elimination for PWM Inverter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93211412376861913471.
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碩士國立交通大學
機械工程系所
102
In this thesis, we discuss about a single-phase DC-AC pulse-width modulated (PWM) inverter system. Actually, the harmonics in the PWM inverter output voltage are often generated as a result of voltage source disturbances. The high-frequency harmonics will filter out by the system itself; nevertheless, the low-frequency harmonics induced by the fundamental component can cause the output ac current to be distorted. A Doubly Coprime Factorization Disturbance Observer (DCFDOB) structure is applied to the DC-AC inverter. This structure can reduce the influence between low-frequency harmonic、system uncertainties and output current without complicated calculations or adding extra circuit components. In implementation, we use the TI Piccolo TMS320F28035 DSP control card. Then the software part including operating procedure, function block, main code, analog-to-digital converter(ADC), interrupt service routine(ISR) and the complete software structure will be introduced. Find the place where DCFDOB control structure is added in the software structure. At last, the result of different condition will be shown and analyze the output current by FFT .
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Li, Szu-Hao, and 李思豪. "Design and Development of Inverter." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/38251608225410447650.
Full textAbstract:
碩士國立宜蘭大學
機械與機電工程學系碩士班
103
With the increasing demand for energy, the development of energy-saving technology has become an important topic for countries around the world. In Taiwan, the amount of industrial electricity is about 53.9% of whole electricity consumption in 2013. How to improve the energy efficiency of industrial equipment is becoming the problem that Taiwan needs to face. Hydraulic systems are widely used in industry because of the characteristics such as small size, high output power, and high stiffness. The traditional valve-controlled hydraulic systems use fixed-frequency induction motors and fixed-displacement pumps, where the excess flow outflows through the valves. Although they have the advantage of quick response, the energy efficiency is low. The variable frequency pump-controlled systems use fixed-displacement pumps, induction motors, and combine with the variable voltage variable frequency inverter. Although they have higher efficiency, the response is slower than the valve-controlled systems. The goal of this research is to achieve a servo hydraulic system having both high energy efficiency and quick response that uses a synchronous motor and fixed-displacement pump, combining with vector control method and realizing the technology of flow and pressure control. The experimental results show that the servo hydraulic system can effectively enhance the energy efficiency and also achieve the quick response to meet the industry requirements.
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Chang, Shiao-Chen, and 張孝丞. "Failures and Troubleshooting of Inverter." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/15636953418871922343.
Full textAbstract:
碩士國立宜蘭大學
機械與機電工程學系碩士班
104
Global warming is increasing the frequency and severity of extreme weather events. The world attention to environment problem, reducing CO2 emissions, saving energy. Industry consumes more than 40% of total world electricity and 74% of this amount is used for electric motor. In recent years, people are not only concerned about the motor efficiency, but also care about the power system efficiency. Inverter which regulate the speed of a motor, can reduce their energy consumption by 50% in many applications, therefore inverter drives are increasingly common in industrial machines. This thesis introduces the types of inverter, specifications, installation and selecting the right inverter. It discusses failures and troubleshooting of inverter from real failure cases. In addition, it also discusses reliability of inverter. Using MIL-HDBK-217F to calculate the lifetime of inverter. The correlation results and suggestions can be used to let the users and researchers of inverter have a broader understanding.
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LI, XIANG, and 李象. "Inverter-induction motor performance analysis." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/60583838454078409230.
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Chen, Chih-Wei, and 陳致瑋. "Development and Implementation of Inverter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/58wnt2.
Full textAbstract:
碩士國立宜蘭大學
機械與機電工程學系
101
In recent years, with the development of power electronics technology, microelectronic technology and control theory, the performance of the inverter is continuously improving, and it has been applied more widely everywhere. Since the development of the inverter, it has focused on a three-phase induction motor. Mainly due to the material progressed in recent years, the permanent magnet synchronous motor is now appearing on the market. Many famous manufacturers began to develop the inverter of the permanent magnet synchronous motor. The current is applied according to the rotor position of the permanent magnet synchronous motor while rotating. Generally, the rotor position is determined by the position sensor. Although, the set up of the position sensor requires extra costs and external device space to design it, and isn’t appropriate in high or low temperatures and pressures. This study is based on the vector inverter and aimed at researching the permanent magnet synchronous motor sensorless control technology. The micro control unit which is produced by TOSHIBA Corporation, combines the back-electromotive force estimation with the PI controller and the phase lock loop sensorless control structure. The experimental results confirm that by combining the back-electromotive force estimation with the PI controller, they can be used in the surface-mounted permanent magnet synchronous motor and the interior permanent magnet synchronous motor.
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Hung, Yung-Chun, and 洪詠竣. "Study of a Soft-switching Single-phase Inverter and Three-phase Modular Connection for Inverters." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/44615258418338978912.
Full textAbstract:
碩士國立宜蘭大學
電機工程學系碩士班
96
This thesis presents a zero-voltage-switching(ZVS) pulse width-modulated (PWM) single-phase inverter and the establishment of a v-connected three-phase inverter using two single-phase modules. All main switching devices in the ZVS-PWM inverter operate at zero-voltage-switching turn on. The auxiliary switches operate at zero-current-switching turned-off. As a result, commutations of the main power devices occur with low losses. Consequently, higher efficiency is achieved. Having established the soft-switching inverter with good output voltage waveform, two modules are connected to form a v-connected soft-switching three-phase inverter. The simulation and experimental results show that rather good three-phase output voltage waveforms can be obtained under linear load and unbalanced load. Finally, some simulation and experimental results are presented for verification. keywords：Pulse Width Modulated (PWM), Zero Voltage Switching (ZVS), Zero Current Switching (ZCS)
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Lakshminarayanan, Sanjay. "Modelling, Simulation And Design Of A Single Switch Resonant Inverter For Induction Heating." Thesis, 1995. https://etd.iisc.ac.in/handle/2005/1647.
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Lakshminarayanan, Sanjay. "Modelling, Simulation And Design Of A Single Switch Resonant Inverter For Induction Heating." Thesis, 1995. http://etd.iisc.ernet.in/handle/2005/1647.
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Lee, Chen-Jong, and 李振榮. "To analyze inverter by optic-interference." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/06372435353056259474.
Full textAbstract:
碩士國立中央大學
光電科學研究所碩士在職專班
90
In recent years，to produce Notebook PC becomes more and more public due its stylish design， compact size and multiple functions。 However，Liquid Crystal Display Module (LCD Mould) occupied one third of Notebook PC design and manufacture costs。 And Inverter Board provides the back light of module LCD is the key component that directly affects the signal output quality and the whole Notebook working efficiency。 The current quality judgment method for inverter board is done by using the electrical oscilloscope to measure high voltage signal。 However，in this paper，it will illustrate the use of Interferometer to analyze the inverter board quality from electro-optical view。By using the Interferometer to measure the roughness of high voltage trace of layout。The quality of inverter bard can be judged through the analysis of the roughness condition。
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Wang, Chi-Nam, and 王旗男. "Multilevel PWM Inverter Control Induction Motor." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/28752679261546760678.
Full textAbstract:
碩士國立雲林科技大學
電機工程系碩士班
89
This paper presents a five-level diode clamp inverter control for induction motor by using simple V/F control law. Multilevel voltage source inverter is based on the extension of two-level inverter. By using the multilevel pulse width modulation scheme, we can obtain better output voltage and current waveform with less harmonics. The advantage of multilevel inverter is using low rated power MOSFET to implement high voltage or high power applications. To implement the adopted multilevel scheme for induction motor , the computer simulations and hardware tests based on digital signal processor (TMS320C50) are presented in this thesis.
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Lee, Thung Ju, and 李宗儒. "Thermal Management of Low Power Inverter." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/49600026860052679017.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
92
ABSTRACT Thermal management is a rapidly growing field in power electronics. This project focuses on thermal management at the system level , using a 2 horsepower front-end inverter as a subject for case study. The establishment of a methodology for using the computer code Icepak to computationally simulate the thermal performance of component temperatures within the system was the primary goal. A series of four benchmarking studies was used to verify the computational results. The comparisons between the computational results and thermocouple measurements show satisfactory agreement. Four modifications to the original inverter design were studied computationally to investigate their effects on the thermal performance of the inverter design. Based on the options explored , an optimum system layout for maximum thermal performance was suggested