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Lund, Richard. "Multilevel Power Electronic Converters for Electrical motor Drives." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-687.
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Power electronic converters are widely used in industrial power conversion systems both for utility and drives applications. As the power level increases, the voltage level is increased accordingly to obtain satisfactory efficiency. During the last years, the voltage rating of fast switching high voltage semiconductors such as the Insulated Gate Bipolar Transistor (IGBT) has increased. Still, there is a need for series connection of switching devices. In this area of applications, the Multilevel Converter has shown growing popularity.
The fundamental advantages of the Multilevel Converter topologies are low distorted output waveforms and limited voltage stress on the switching devices. The main disadvantages are higher complexity and more difficult control.
In this thesis, Multilevel Converters are analysed for large motor drive applications. The main focus has been on converter losses, output waveform quality and control.
Analytical expressions for both switching and conduction losses for 4- and 5-level Diode Clamped Converters have been developed. The investigation shows that the losses can be reduced by utilizing a multilevel topology for a 1 MW drive. This work is presented in [46]. The same reduction in losses is proven for a 2300V/ 3 MW drive.
Analytical expressions for the harmonic losses in 3-level converters have been developed for 2 different Carrier Based PWM schemes, presented in [56], [57] and [58]. Also Space Vector PWM are investigated and compared by simulations, in addition to 4- and 5-level Carrier Based PWM.
DC-bus balancing in both 3- and 5-level converters is discussed. Balancing in 3- level converters can be achieved by proper control. Balancing in 5-level converters can be achieved by proper arrangement of isolated DC-supplies.
One 40kW 3-level converter and one 5kW 5-level converter has been designed and built. Experimental verification of the analytical and simulated results is shown.
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Pickert, Volker. "Assessment of novel power electronic converters for drives applications." Thesis, University of Newcastle Upon Tyne, 1999. http://hdl.handle.net/10443/498.
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In the last twenty years, industrial and academic research has produced over one hundred new converter topologies for drives applications. Regrettably, most of the published work has been directed towards a single topology, giving an overall impression of a large number of unconnected, competing techniques. To provide insight into this wide ranging subject area, an overview of converter topologies is presented. Each topology is classified according to its mode of operation and a family tree is derived encompassing all converter types. Selected converters in each class are analysed, simulated and key operational characteristics identified. Issues associated with the practical implementation of analysed topologies are discussed in detail. Of all AC-AC conversion techniques, it is concluded that softswitching converter topologies offer the most attractive alternative to the standard hard switched converter in the power range up to 100kW because of their high performance to cost ratio. Of the softswitching converters, resonant dc-link topologies are shown to produce the poorest output performance although they offer the cheapest solution. Auxiliary pole commutated inverters, on the other hand, can achieve levels of performance approaching those of the hard switched topology while retaining the benefits of softswitching. It is concluded that the auxiliary commutated resonant pole inverter (ACPI) topology offers the greatest potential for exploitation in spite of its relatively high capital cost. Experimental results are presented for a 20kW hard switched inverter and an equivalent 20kW ACPI. In each case the converter controller is implanted using a digital signal processor. For the ACPI, a new control scheme, which eliminates the need for switch current and voltage sensors, is implemented. Results show that the ACPI produces lower overall losses when compared to its hardswitching counterpart. In addition, device voltage stress, output dv/dt and levels of high frequency output harmonics are all reduced. Finally, it is concluded that modularisation of the active devices, optimisation of semiconductor design and a reduction in the number of additional sensors through the use of novel control methods, such as those presented, will all play a part in the realisation of an economically viable system.
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Francis, Gerald. "A Synchronous Distributed Digital Control Architecture for High Power Converters." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/31942.
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Power electronics applications in high power are normally large, expensive, spatially distributed systems. These systems are typically complex and have multiple functions. Due to these properties, the control algorithm and its implementation are challenging, and a different approach is needed to avoid customized solutions to every application while still having reliable sensor measurements and converter communication and control.
This thesis proposes a synchronous digital control architecture that allows for the communication and control of devices via a fiber optic communication ring using digital technology. The proposed control architecture is a multidisciplinary approach consisting of concepts from several areas of electrical engineering. A review of the state of the art is presented in Chapter 2 in the areas of power electronics, fieldbus control networks, and digital design. A universal controller is proposed as a solution to the hardware independent control of these converters. Chapter 3 discusses how the controller was specified, designed, implemented, and tested. The power level specific hardware is implemented in modules referred to as hardware managers. A design for a hardware manager was previously implemented and tested. Based on these results and experiences, an improved hardware manager is specified in Chapter 4. A fault tolerant communication protocol is specified in Chapter 5. This protocol is an improvement on a previous version of the protocol, adding benefits of improved synchronization, multimaster support, fault tolerant structure with support for hot-swapping, live insertion and removals, a variable ring structure, and a new network based clock concept for greater flexibility and control. Chapter 6 provides a system demonstration, verifying the components work in configurations involving combinations of controllers and hardware managers to form applications. Chapter 7 is the conclusion. VHDL code is included for the controller, the hardware manager, and the protocol. Schematics and manufacturing specifications are included for the controller.
Master of Science
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Anthony, Philip Henry. "A study of resonant gate drivers and their application in high efficiency power electronic converters." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618548.
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This thesis describes a study of resonant gate drivers and their application in high-efficiency power electronic converters, including: • The development of a general modelling approach and design method for resonant gate drivers, including topologies which contain a galvanic isolation boundary. • The re-creation of resonant gate drivel' topologies in the published literature using the proposed design method. • The re-creation of new resonant gate driver topologies using the proposed design method. • The design, construction, and use of universal resonant gate driver test hardware, for replicating the behaviour of any topology conforming to the proposed resonant gate driver model. • The design, construction and evaluation of an improved gate driver for a silicon carbide MOSFET, enabling a reduction in switching loss under representative loading conditions. • The design, construction and evaluation of an improved isolated resonant gate driver for silicon super-junction MOSFETs, capable of reducing the gate driver power consumption in comparison to conventional gate driving techniques.
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Falck, Johannes [Verfasser], Marco [Akademischer Betreuer] Liserre, Jörg [Gutachter] Roth-Stielow, and Thomas [Gutachter] Meurer. "Thermal Stress Based Model Predictive Control of Power Electronic Converters in Electric Drives Applications / Johannes Falck ; Gutachter: Jörg Roth-Stielow, Thomas Meurer ; Betreuer: Marco Liserre." Kiel : Universitätsbibliothek Kiel, 2021. http://d-nb.info/1232726362/34.
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Jalili, Kamran. "Investigation of Control Concepts for High-Speed Induction Machine Drives and Grid Side Pulse-Width Modulation Voltage Source Converters." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A25053.
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Control of a low voltage ac/dc/ac converter for high-speed induction machine drive applications has been investigated. Such a configuration can be applied, for example, in microturbines and high-speed spindles.
Scalar control is usually applied for the control of high-speed drives especially in the case of very high-speed drives. Indirect rotor-flux-oriented control and direct torque control are designed and compared for the control of an exemplary high-speed induction machine drive.
The 2L VSC is the most widely applied converter for high-speed drives. However, the 3L-NPC VSC is an attractive topology if drastically increased switching frequencies are required. A detailed comparison between a 2L VSC and a 3L-NPC VSC as the machine side converter of the exemplary high-speed induction machine drive is carried out.
Voltage-oriented control is applied for the control of the grid side PWM active front end converter. In several industrial applications PWM active front end converters commonly operate in parallel to thyristor converter fed dc drives. Behavior of the voltage-oriented controlled active front end converter with L-filter in the presence of a parallel thyristor converter is investigated.
The design of the LCL-filter components according to the given maximum grid current harmonics (e.g. IEEE-519) is a complex task. So far a precise and clear design procedure has not been presented. A new procedure to design the grid side filter (L- and LCL-filter) is proposed using the analytical expression of the converter voltage harmonics based on Bessel functions to achieve the compliance with the grid standard of IEEE-519. Voltage-oriented control with active damping is used to control the active front end converter with LCL-filter. A simple method is proposed to design the required lead-lag compensator in the active damping loop.
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Jalili, Kamran. "Investigation of control concepts for high speed induction machine drives and grid side pulse width modulation voltage source converters." Doctoral thesis, Berlin mbv, 2009. http://d-nb.info/995880107/04.
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Montasser, Yuseph. "Design and Development of a Power Modulator for Insulation Testing." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2895.
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Variable speed drives allow for more precise speed control of induction motors, are of high power factor, and offer fast response characteristics, compared to older technologies, such as motor-generator sets and eddy current clutches. However, due to the high switching frequencies as well as the high dV/dt in the output increased dielectric stresses are produced in the insulation system of the motor they supply. Due to the use of these solid state drives there have been concerns of premature failure in large, medium and high voltage, motors. To fully understand and deal with these concerns requires studying the degradation mechanisms, in the insulation system, caused by these drives; which, on an actual motor is both extremely costly as well as impractical. Therefore, coil samples which accurately represent the construction of the actual insulation system, must be aged and studied instead. In addition, to ideally replicate the aging process, the same waveform that the motor is subjected to must be applied to these samples. As a result of this requirement, a low power, two-level, high voltage PWM inverter has been built to replicate the most important characteristics of the output waveform of a variable speed drive. This power modulator allows for testing the insulation systems considering a real PWM waveform in which both the fast pulses and the fundamental low frequency are included. The results of these tests show that the effects of PWM waveforms cannot be entirely replicated by a unipolar pulse generator.
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Narayanan, G. "Synchronised Pulsewidth Modulation Strategies Based On Space Vector Approach For Induction Motor Drives." Thesis, Indian Institute of Science, 1999. http://hdl.handle.net/2005/139.
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In high power induction motor drives, the switching frequency of the inverter is quite low due to the high losses in the power devices. Real-time PWM strategies, which result in reduced harmonic distortion under low switching frequencies and have maximum possible DC bus utilisation, are developed for such drives in the present work.
The space vector approach is taken up for the generation of synchronised PWM waveforms with 3-Phase Symmetry, Half Wave Symmetry and Quarter Wave Symmetry, required for high-power drives. Rules for synchronisation and the waveform symmetries are brought out. These rules are applied to the conventional and modified forms of space vector modulation, leading to the synchronised conventional space vector strategy and the Basic Bus Clamping Strategy-I, respectively. Further, four new synchronised, bus-clamping PWM strategies, namely Asymmetric Zero-Changing Strategy, Boundary Sampling Strategy-I, Basic Bus Clamping Strategy-II and Boundary Sampling Strategy-II, are proposed. These strategies exploit the flexibilities offered by the space vector approach like double-switching of a phase within a subcycle, clamping of two phases within a subcycle etc. It is shown that the PWM waveforms generated by these strategies cannot be generated by comparing suitable 3-phase modulating waves with a triangular carrier wave.
A modified two-zone approach to overmodulation is proposed. This is applied to the six synchronised PWM strategies, dealt with in the present work, to extend the operation of these strategies upto the six-step mode. Linearity is ensured between the magnitude of the reference and the fundamental voltage generated in the whole range of modulation upto the six-step mode. This is verified experimentally.
A suitable combination of these strategies leads to a significant reduction in the harmonic distortion of the drive at medium and high speed ranges over the conventional space vector strategy. This reduction in harmonic distortion is demonstrated, theoretically as well as experimentally, on a constant V/F drive of base frequency 50Hz for three values of maximum switching frequency of the inverter, namely 450Hz, 350Hz and 250Hz.
Based on the notion of stator flux ripple, analytical closed-form expressions are derived for the harmonic distortion due to the different PWM strategies. The values of harmonic distortion, computed based on these analytical expressions, compare well with those calculated based on Fourier analysis and those measured experimentally.
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Bonavoglia, Marco <1987>. "Power Converters and Electric Drives for Smart Grid Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6778/1/Bonavoglia_Marco_tesi.pdf.
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The present dissertation aims to explore, theoretically and experimentally, the problems and the potential advantages of different types of power converters for “Smart Grid” applications, with particular emphasis on multi-level architectures, which are attracting a rising interest even for industrial requests.
The models of the main multilevel architectures (Diode-Clamped and Cascaded) are shown. The best suited modulation strategies to function as a network interface are identified. In particular, the close correlation between PWM (Pulse Width Modulation) approach and SVM (Space Vector Modulation) approach is highlighted.
An innovative multilevel topology called MMC (Modular Multilevel Converter) is investigated, and the single-phase, three-phase and "back to back" configurations are analyzed. Specific control techniques that can manage, in an appropriate way, the charge level of the numerous capacitors and handle the power flow in a flexible way are defined and experimentally validated.
Another converter that is attracting interest in “Power Conditioning Systems” field is the “Matrix Converter”. Even in this architecture, the output voltage is multilevel. It offers an high quality input current, a bidirectional power flow and has the possibility to control the input power factor (i.e. possibility to participate to active and reactive power regulations). The implemented control system, that allows fast data acquisition for diagnostic purposes, is described and experimentally verified.
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Bonavoglia, Marco <1987>. "Power Converters and Electric Drives for Smart Grid Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6778/.
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The present dissertation aims to explore, theoretically and experimentally, the problems and the potential advantages of different types of power converters for “Smart Grid” applications, with particular emphasis on multi-level architectures, which are attracting a rising interest even for industrial requests.
The models of the main multilevel architectures (Diode-Clamped and Cascaded) are shown. The best suited modulation strategies to function as a network interface are identified. In particular, the close correlation between PWM (Pulse Width Modulation) approach and SVM (Space Vector Modulation) approach is highlighted.
An innovative multilevel topology called MMC (Modular Multilevel Converter) is investigated, and the single-phase, three-phase and "back to back" configurations are analyzed. Specific control techniques that can manage, in an appropriate way, the charge level of the numerous capacitors and handle the power flow in a flexible way are defined and experimentally validated.
Another converter that is attracting interest in “Power Conditioning Systems” field is the “Matrix Converter”. Even in this architecture, the output voltage is multilevel. It offers an high quality input current, a bidirectional power flow and has the possibility to control the input power factor (i.e. possibility to participate to active and reactive power regulations). The implemented control system, that allows fast data acquisition for diagnostic purposes, is described and experimentally verified.
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Giussani, Riccardo. "PD monitoring of power electronic converters." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/pd-monitoring-of-power-electronic-converters(eea30376-4752-416c-a046-2773a21064c4).html.
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Wind turbine converters used in multi-megawatt machines will operate at high voltages, particularly in future generations of wind turbines where direct connections to a HVDC backbone are made. Given the pressure to achieve high power densities in a converter to minimise the space utilised, the pressure on the high voltage insulation system to be reduced in size to the minimum possible is great. With it, this brings the increased risk of electrical discharge within the system insulation. The PhD project has therefore examined a number of issues: a) Evaluation of the risks posed to HV power electronic systems from electrical discharge: on the basis of a literature survey, discussions with converter manufacturers and the application of standard HV engineering models, the risks to a power electronic system in the wind turbine application will be assessed. b) Theoretical assessment of potential monitoring techniques: Given the risks that have been described in (a) above, the possible ways in which monitoring could be applied will be investigated. Each risk will be assessed to confirm that discharge mechanism that results in failure/damage will produce some form of measurable signal (whether this is through voltage, current acoustic, RF etc.). c) Experimental assessment of sensors for use in HV power electronic monitoring: Using a HV source within an anechoic chamber (to provide RF and acoustic noise reduction), a range of HV defects that could occur in power electronic systems will be simulated. The ability of suitably characterised sensors to detect the defects will be assessed. The research has then focus on RF detection of PD to develop a measurement method that can be applied to operating s power electronic converters (EPC).Firstly the RF emissions of several types of discharge have been studied in depth alongside the study of the effect of the environmental pressure on the signature of the different discharges. Then, the knowledge gathered was applied to perform and verify the effectiveness of RF measurements to online detect PD within operating EPC. Finally the applicability of the RF technique was verified for the detection of other electrical discharges (non-PD like) as electrical tracking.
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Bishnoi, Hemant. "Behavioral EMI-Models of Switched Power Converters." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23936.
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Measurement-based behavioral electromagnetic interference (EMI) models have been shown earlier to accurately capture the EMI behavior of switched power converters. These models are compact, linear, and run in frequency domain, enabling faster and more stable simulations compared to the detailed lumped circuit models. So far, the behavioral EMI modeling techniques are developed and applied to the converter's input side only. The resulting models are therefore referred to as "terminated EMI models". Under the condition that the output side of the converter remains fixed, these models can predict the input side EMI for any change in the impedance of the input side network. However, any change at the output side would require re-extraction of the behavioral model. Thus the terminated EMI models are incapable of predicting the change in the input side EMI due to changes at the output side of the converter or vice versa.
The above mentioned limitation has been overcome by an "un-terminated EMI model" proposed in this dissertation. Un-terminated EMI models are developed here to predict both the common-mode (CM) and the differential (DM) noise currents at the input and the output sides of a motor-drive system. The modeling procedure itself has been simplified and now requires fewer measurements and results in less noise in the identified model parameters. Both CM and DM models are then combined to predict the total noise in the motor drive system. All models are validated by experiments and their limitations identified.
A significant portion of this dissertation is then devoted to the application of behavioral EMI models in the design of EMI filters. Comprehensive design procedures are developed for both DM and CM filters in a motor-drive system. The filters designed using the proposed methods are experimentally shown to satisfy the DO-160 conducted emissions standards.
The dissertation ends with a summary of contributions, limitations, and some future research directions.Ph. D.
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Rojas, Dueñas Gabriel. "Modeling and identification of power electronic converters." Doctoral thesis, Universitat Politècnica de Catalunya, 2022. http://hdl.handle.net/10803/673581.
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Nowadays, many industries are moving towards more electrical systems and components. This is done with the purpose of enhancing the efficiency of their systems while being environmentally friendlier and sustainable. Therefore, the development of power electronic systems is one of the most important points of this transition. Many manufacturers have improved their equipment and processes in order to satisfy the new necessities of the industries (aircraft, automotive, aerospace, telecommunication, etc.). For the particular case of the More Electric Aircraft (MEA), there are several power converters, inverters and filters that are usually acquired from different manufacturers. These are switched mode power converters that feed multiple loads, being a critical element in the transmission systems. In some cases, these manufacturers do not provide the sufficient information regarding the functionality of the devices such as DC/DC power converters, rectifiers, inverters or filters. Consequently, there is the need to model and identify the performance of these components to allow the aforementioned industries to develop models for the design stage, for predictive maintenance, for detecting possible failures modes, and to have a better control over the electrical system.
Thus, the main objective of this thesis is to develop models that are able to describe the behavior of power electronic converters, whose parameters and/or topology are unknown. The algorithms must be replicable and they should work in other types of converters that are used in the power electronics field. The thesis is divided in two main cores, which are the parameter identification for white-box models and the black-box modeling of power electronics devices. The proposed approaches are based on optimization algorithms and deep learning techniques that use non-intrusive measurements to obtain a set of parameters or generate a model, respectively. In both cases, the algorithms are trained and tested using real data gathered from converters used in aircrafts and electric vehicles. This thesis also presents how the proposed methodologies can be applied to more complex power systems and for prognostics tasks. Concluding, this thesis aims to provide algorithms that allow industries to obtain realistic and accurate models of the components that they are using in their electrical systems.En la actualidad, el uso de sistemas y componentes eléctricos complejos se extiende a múltiples sectores industriales. Esto se hace con el propósito de mejorar su eficiencia y, en consecuencia, ser más sostenibles y amigables con el medio ambiente. Por tanto, el desarrollo de sistemas electrónicos de potencia es uno de los puntos más importantes de esta transición. Muchos fabricantes han mejorado sus equipos y procesos para satisfacer las nuevas necesidades de las industrias (aeronáutica, automotriz, aeroespacial, telecomunicaciones, etc.). Para el caso particular de los aviones más eléctricos (MEA, por sus siglas en inglés), existen varios convertidores de potencia, inversores y filtros que suelen adquirirse a diferentes fabricantes. Se trata de convertidores de potencia de modo conmutado que alimentan múltiples cargas, siendo un elemento crítico en los sistemas de transmisión. En algunos casos, estos fabricantes no proporcionan la información suficiente sobre la funcionalidad de los dispositivos como convertidores de potencia DC-DC, rectificadores, inversores o filtros. En consecuencia, existe la necesidad de modelar e identificar el desempeño de estos componentes para permitir que las industrias mencionadas desarrollan modelos para la etapa de diseño, para el mantenimiento predictivo, para la detección de posibles modos de fallas y para tener un mejor control del sistema eléctrico. Así, el principal objetivo de esta tesis es desarrollar modelos que sean capaces de describir el comportamiento de un convertidor de potencia, cuyos parámetros y/o topología se desconocen. Los algoritmos deben ser replicables y deben funcionar en otro tipo de convertidores que se utilizan en el campo de la electrónica de potencia. La tesis se divide en dos núcleos principales, que son la identificación de parámetros de los convertidores y el modelado de caja negra (black-box) de dispositivos electrónicos de potencia. Los enfoques propuestos se basan en algoritmos de optimización y técnicas de aprendizaje profundo que utilizan mediciones no intrusivas de las tensiones y corrientes de los convertidores para obtener un conjunto de parámetros o generar un modelo, respectivamente. En ambos casos, los algoritmos se entrenan y prueban utilizando datos reales recopilados de convertidores utilizados en aviones y vehículos eléctricos. Esta tesis también presenta cómo las metodologías propuestas se pueden aplicar a sistemas eléctricos más complejos y para tareas de diagnóstico. En conclusión, esta tesis tiene como objetivo proporcionar algoritmos que permitan a las industrias obtener modelos realistas y precisos de los componentes que están utilizando en sus sistemas eléctricos.
Enginyeria elèctrica
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GOMEZ, GOMEZ MANUEL. "Multi-objective optimization of power electronic converters." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2903502.
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Falk, Olson Gustaf. "Power Electronic Stages for a TFPMSM in Wave Power Applications." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-194201.
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Direct drive wave energy conversion systems have been identified as a potentially major contributor to the world’s energy demands, forecasting shares of up to 25 % of the energy mix. Anders Hagnestål conducts research at the Royal Institute of Technology where a novel linear transverse flux permanent magnet generator is developed. This concept machine is particularly well-suited for the pertaining operating conditions in marine environments, producing large forces at low speeds with outstandingly low resistive losses. However, it exhibits severe magnetic saturation and draws unsymmetrical phase currents at nominal operation. In addition, it possesses a low power factor. All in all, this places stern requirements on the power electronic system and control algorithms. The aim of this thesis has been to design a functioning power conditioning system that connects the machine to the electric grid. For this purpose, a three-phase two-level voltage source converter is proposed to be back-to-back connected with two-level single-phase voltage source converters (active rectifiers) interfacing each and every machine phase. It is shown that the intermediate DC link can be maintained at a constant voltage with restricted ripple while feeding power at unity power factor to the grid by appropriately sizing the DC capacitor and adopting a feedback linearization control scheme. The phase currents can be controlled effectively by means of a cascaded gain-scheduled PID controller. By including a low-pass filter the iron losses in the machine may be suppressed even at lower switching frequencies. A constrained cost optimization indicates that the converter consequently can reach 99.1 % efficiency. Finally, with this thesis as a background, it is suggested that the thermal stresses on the selected semiconductor modules and the iron losses of the machine are evaluated to further improve the design. If higher efficiency of the active rectifiers is strived for, more complex converter topologies could be considered.Direktdrivna vågenergiomvandlingssystem har utpekats som en potentiellt starkt bidragande resurs för att tillgodose världens efterfrågan på energi med andelar på uppemot 25 % av energimixen förutspådda. Anders Hagnestål bedriver forskning och utveckling av en ny typ av linjär permanentmagnetiserad transversalflödesmaskin vid Kungliga Tekniska Högskolan. Konceptmaskinen är särskilt väl lämpad för de rådande marina förhållandena genom att kunna producera stora krafter vid låga hastigheter med utomordentligt låga resistiva förluster. Maskinen går emellertid i kraftig magnetisk mättnad och drar asymmetriska strömmar vid nominell drift. Dessutom är effektfaktorn låg i jämförelse med standardmaskiner. Alltsomallt inför detta hårda krav på det effektelektroniska systemet och kontrollalgoritmerna. Målet med detta examensarbete har varit att designa ett funktionellt effektkonditioneringssystem som sammanfogar maskinen med det angränsande elektriska nätet. För att åstadkomma detta föreslås att en tvånivås-trefasomriktare kopplas rygg-mot-rygg till tvånivås-enfasomvandlare (aktiva likriktare) som i sin tur är kopplade till varje maskinfas. Med den här konfigurationen visas det att spänningen på den mellanliggande DC-länken kan hållas konstant med begränsat rippel, alltmedan effekt tillförs nätet vid effektfaktor ett genom att dimensionera DC-kondensatorn på rätt sätt och använda en kontrollag baserad på exakt linjärisering. Maskinens fasströmmar kan kontrolleras effektivt med hjälp av en kaskadkopplad PID-regulator med schemalagda förstärkningsfaktorer. Genom att inkludera ett lågpassfilter förväntas det att järnförlusterna i maskinen kan begränsas även vid lägre switchfrekvenser. Genom att lösa ett kostnadsoptimeringsproblem visas det att den resulterande aktiva likriktaren kan uppnå en verkningsgrad på 99.1 %. Slutligen, med det här examensarbetet som grund, föreslås det att den termiska stressen på de valda halvledarkomponentsmodulerna och järnförlusterna i maskinen utvärderas för att ytterligare förbättra designen. Om högre verkningsgrad eftersträvas hos de aktiva likriktarna kan mer komplicerade omvandlartopologier övervägas.
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Espinoza, Bolaños Mauricio Antonio. "Control systems for high-power medium-voltage modular multilevel converter-based drives." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/168418.
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Doctor en Ingeniería EléctricaHoy en día, la construcción de maquinaria y plantas industriales exigen soluciones de accionamiento con un diseño flexible y escalable. En sectores industriales como la petroquímica, la minería, la generación de energía, etc., existe una demanda de soluciones con alta eficiencia, seguridad integrada y respaldo de las compañías proveedoras. En este contexto, el Convertidor Multinivel Modular (MMC) ha aparecido como una opción prometedora para accionamientos de media tensión de alta potencia debido a sus características, como modularidad total, flexibilidad de control, niveles de media tensión, calidad de potencia y posible operación sin transformador. Por lo tanto, esta tesis discute la aplicación del MMC para accionamientos de máquinas. El modelado del MMC y sus sistemas de control asociados para esta aplicación son analizados ampliamente en este documento. Específicamente, se ha propuesto un nuevo modelado basado en coordenadas dq y su sistema correspondiente sistema de control para regular el valor instantáneo de las tensiones de los condensadores del MMC. Además, se ha propuesto la integración de los sistemas de control de la máquina y del MMC para mejorar el rendimiento general del sistema. Por ejemplo, se demostró que las corrientes circulantes requeridas durante bajas frecuencias ac se reducen al considerar la interacción de ambos sistemas de control. La efectividad de las estrategias de control propuestas se validó a través de extensos resultados experimentales, que se han publicado en dos artículos (IEEE Transactions on Industrial Electronics) y seis artículos de conferencia (indexados en la base de datos Scopus), así como contribuciones importantes en otros proyectos relacionados con el control de convertidores multinivel modulares. El prototipo utilizado se compone de 18 celdas de potencia. El sistema se controla utilizando un procesador de señales digitales y dos FPGAs. Un segundo MMC con 12 celdas de potencia también se usó para algunas pruebas, conformando una unidad Back-to-Back MMC. Se probó el rendimiento dinámico y en estado estable de las metodologías de control propuestas, considerando el arranque del MMC, cambios escalón tanto en el par y las corrientes de magnetización, rampas de velocidad, pruebas de cruce por velocidad cero, operación de rotor bloqueado, operación con flujo debilitado, diferentes condiciones de carga, manipulación de la tensión dc del MMC, etc. En todos los casos, el rendimiento alcanzado es consistente con los resultados esperados. Nowadays, machinery and plant construction are demanding drive solutions with flexible and scalable design. In industrial sectors such as petrochemical, mining, power generation, etc., there is a demand for solutions with high efficiency, integrated safety and support from the supplier companies. In this context, the Modular Multilevel Converter (MMC) has appeared as a promising option for high-power medium-voltage drives due to their characteristics, such as full modularity, control flexibility, medium-voltage levels, power quality and possible transformer-less operation. Thereby, this thesis discusses the application of the MMC as a machine drive. The modelling and control systems required for this application are extensively analysed and discussed in this document. Specifically, a novel dq-based modelling of the MMC and its associated control system has been proposed to regulate the instantaneous value of the MMC capacitor voltages. Additionally, the integration of the machine and MMC control systems has been proposed to enhance the performance of the overall system. For example, it was demonstrated that the required circulating currents during low-ac frequencies are reduced by considering the interaction of both control systems. The effectiveness of the proposed control strategies is validated through extensive experimental results, which have been published in two journal papers (IEEE Transaction on Industrial Electronics) and six conference papers (indexed in the Scopus database), as well as important contributions in other projects related to the control of modular multilevel converters. The downscaled prototype utilised is composed of 18 power cells. The system is controlled using a Digital Signal Processor and two Field Programmable Gate Arrays (FPGAs). A second MMC with 12 power cells was also used for some tests, conforming a Back-to-Back MMC-based drive. The dynamic and steady-state performance of the proposed control methodologies were tested, considering the MMC starting-up, step changes in both the torque and magnetising currents, speed-ramps, zero-speed crossing test, rotor-locked operation, flux-weakening operation, different loading conditions, manipulation of the input voltage of the MMC, etc. In all cases, the achieved performance is consistent with the expected results.
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Broadmeadow, Mark A. "Characterisation of the cascode gate drive of power MOSFETs in clamped inductive switching applications." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/82868/4/Mark%20Broadmeadow%20Thesis.pdf.
Full textAbstract:
This thesis proposes a novel gate drive circuit to improve the switching performance of MOSFET power switches in power electronic converters. The proposed topology exploits the cascode configuration, allowing the minimisation of switching losses in the presence of practical circuit constraints, which enables efficiency and power density improvements. Switching characteristics of the new topology are investigated and key mechanisms that control the switching process are identified. Unique analysis tools and techniques are also developed to demonstrate the application of the cascode gate drive circuit for switching performance optimisation.
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Kumar, Dinesh. "A new multi-motor drive system based on two-stage direct power converter." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/13515/.
Full textAbstract:
The two-stage AC to AC direct power converter is an alternative matrix converter topology, which offers the benefits of sinusoidal input currents and output voltages, bidirectional power flow and controllable input power factor. The absence of any energy storage devices, such as electrolytic capacitors, has increased the potential lifetime of the converter. In this research work, a new multi-motor drive system based on a two-stage direct power converter has been proposed, with two motors connected on the same shaft. A vector control scheme is proposed where each motor has an independent current control loop, but shares a single speed control loop. The two-motor on the same shaft solution has applications in aerospace to increase the availability of the system. The two-stage direct power converter therefore offers the possibility of a cost effective multi-motor drive system. The feasibility and performance of the proposed multi-motor drive system is demonstrated through simulation results and validated with experimental results from a laboratory prototype.
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Hoff, Erik Stjernholm. "Distributed Generation - Power Electronic Converters, Communication and Control." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1620.
Full textAbstract:
This thesis tries to explain the changes in the control of power electronic converters that are possible by the use of communication. Many of the renewable energy sources such as photovoltaic panels are geographically dispersed. The power rating per generator is therefore typically low. If this kind of energy source should dominate an electrical grid, the number of generators must be high. There should also be means of controlling this large number of generators simultaneously and safely. The cost of safe communication may be too high compared to the power contribution of a single generator. The Internet offers a low-cost solution, but it cannot guarantee real-time properties. Similarly to the Internet itself, it is shown how communication errors can be detected and handled in a safe manner by the end-system, in this case the generator. The generator can detect a communication timeout, and change control algorithms in order to guard itself and the connected electricity grid. When necessary, it can also disconnect and work as a local standalone power supply. In order to be able to supply all kinds of loads, the generator (in this case an inverter) is primarily voltage controlled. This results in challenges concerning current distortion. The use of feed-forward for cancellation of common grid voltage harmonics is discussed, simulated and measured. An anti-islanding algorithm for voltage controlled inverters is also developed, simulated and measured in this thesis. A DC/DC-converter for optimized connection of a photovoltaic panel is built, exploiting the photovoltaic panel properties to reduce the size and the losses significantly. Although most contributions are connected to details and parts of the system, the interactions between communication and control are emphasized.
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Thong, Weng Kwai. "Power electronic converters for motors with bifilar windings." Thesis, University of Leicester, 2005. http://hdl.handle.net/2381/30231.
Full textAbstract:
There is a high demand to improve performance and efficiency of motors used in domestic applications but there is constant downward pressure on manufacturing cost. This thesis identifies switched reluctance motors and flux switching motors as being low cost brushless motor technology and shows that bifilar windings can lead to lower cost electronic converters.;The thesis develops innovative power electronic converters for motor incorporating bifilar windings. Novel circuits for reliable capture, dissipation or recovery of energy associated with leakage inductance of the closely coupled bifilar windings are presented.;Two applications identified are dual voltage drives and bipolar excited motor drives. Several bifilar converter drives are presented in detail in this thesis. These include converters with dissipative snubbers, converters with energy recovery snubbers, converters with nondissipative snubbers and converters with inherent freewheel capability. Each of the presented converters offers advantages in cost and/or performance over existing converters.
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StankoviÄ, Aleksandar Mihajla. "Random pulse modulation with applications to power electronic converters." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12589.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.Includes bibliographical references (leaves 192-203).
by Aleksandar Mihajla StankoviÄ.
Ph.D.
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Rasouli, Disfani Vahid. "Optimization and Control for Microgrid and Power Electronic Converters." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5764.
Full textAbstract:
The proposed dissertation research investigates Optimization and Control for Microgrid and Power Electronic Converters. The research has two major parts:
i- Microgrid Operation and Control,
ii- Power Electronic Converter Control and Optimization.
In the first part, three focuses are investigated. First, a completely distributed algorithm is developed for dc optimal power flow problem for power distribution systems as one of the necessary functions considered in unit-commitment problem in day-ahead markets. This method is derived based upon the partial primal-dual representation of the economic dispatch problem, which is finally translated to DC-OPF problem. Second, the optimal interaction between the utility and communities will be studied, due to its improtance in real-time markets. The objective of this section will be to develop an iterative agent-based algorithm for optimal utility-community control. The algorithm will consider the AC power system constraints to maintain power system stability. In this algorithm, a simplified model of microgrid is considered. In the third focus, a comprehensive model of microgrid is taken into account. The optimal operation of the microgrid considering energy storage systems and renewable energy resources is investigated. The interaction of such microgrids with the main grid to define the optimal operation of the entire embedded system is studied through two iterative methods. In the microgrid's internal problem, a moving-horizon algorithm is considered to define the optimal dispatch of all distributed energy resources while considering the time-correlated constraints of energy storage systems. A thorough analysis of the effects of the size of storage systems on energy and reserve market parameters are also performed.
In the second part, the focus of research is to develop optimal control strategies for Power Electronic Converters. A Model Predictive Control (MPC) switching method is proposed for Modular Multilevel Converters (MMC). The optimal solution of MPC problem is then represented as an optimization problem. Due to lack of efficient algorithms to seek the optimal solution, a fast algorithm will be proposed in this research. The method proposed reduces the number of possible solutions and computation efforts dramatically.
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Ming, Wen-Long. "Active control of voltage ripples in power electronic converters." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/12343/.
Full textAbstract:
Two major challenges, i.e., bulky electrolytic capacitors and isolation transformers, remain as critical obstacles for further improvement on reliability, power density and efficiency of power electronic converters, which are mainly used to reduce low-frequency voltage ripples and high-frequency common-mode voltage ripples, respectively. In order to overcome the two challenges, the most straightforward way is to simply combine existing solutions developed for each of them. However, this would considerably increase system complexity and cost, which should be avoided if possible. In this thesis, these two challenges are innovatively addressed in a holistic way by using active control techniques. This thesis first focuses on the reduction of low-frequency voltage ripples in conventional half-bridge converters, after adding an actively-controlled neutral leg. As a direct application of this strategy, a single-phase to three-phase conversion is then proposed. After that, a ρ-converter with only four switches is proposed to significantly reduce both low-frequency ripples and high-frequency common-mode ripples in a holistic way. It is found that the total capacitance can be reduced by more than 70 times compared to that in conventional full-bridge converters. As a result, there is no longer a need to use bulky electrolytic capacitors and isolation transformers. Then, the ρ-converter equipped with the synchronverter technology is operated as an inverter for PV applications. Another converter is also proposed for the same purpose but with reduced voltage stress. In order to further reduce the total capacitance and to reduce the neutral inductor in the ρ-converter, a new type of converter, called the θ-converter, is proposed. Finally, two actively-controlled ripple eliminators are proposed to reduce low-frequency ripples in general DC systems while the aforementioned research is focused on some specific topologies. Extensive experimental results are presented to validate most of the developed systems while the rest are validated with simulation results.
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Liu, Guangyuan. "Advanced Controllers of Power Electronic Converters in DC Microgrids." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3422330.
Full textAbstract:
To cope with the pressure of climate change and depletion of fossil fuels, distributed power generation based on sustainable and green resources, such as photovoltaic and wind, have been exploited over the past decades. High penetration of renewable energy sources challenges the normal operation of traditional power grids, due to their characteristics of intermittence and uncertainty. To address this issue, an effective way is to aggregate distributed generators, energy storage systems, and customer loads together, as a single entity, that is, the so-called microgrids. Every microgrid is a fully dispatchable unit for grid operators, relieving the strains brought by renewable energy sources. Also, microgrids are able to provide reliable power for customer loads by supporting autonomous operation. Distributed energy resources are linked to microgrids by means of power electronic converters. As most of resources and future appliances are DC in nature, DC microgrids are more appealing than their AC counterparts. They can potentially achieve higher energy conversion efficiency and lower system costs, mainly by minimizing the number of DC-AC and AC-DC power conversion stages.
Droop control is a common decentralized solution to implement primary level control. With the droop control method, DC bus voltage is employed to convey the loading condition of DC microgrids, and load power can be automatically allocated among parallel resource converters. This dissertation focuses on performance improvement of droop-controlled converters, mainly in the following three aspects: i) reduction of DC bus capacitance while maintaining tight DC bus voltage regulation; ii) suppression of second-order harmonic current flowing into distributed energy resources; iii) smooth transfer from power flow control to droop control, allowing DC microgrids to seamlessly disconnect from upstream grids.
The first aspect: one of the constrains to reduce DC bus capacitance is the voltage surges and sags during load changes. From this point of view, resistive output impedance is a better design option than non-resistive output impedance for resource converters. This is because, given a certain output voltage tolerance band, resistive output impedance allows larger voltage dynamic variations, so that smaller output capacitance can be used. A systematical design approach, including the selection criteria of output capacitance and the design of droop coefficient, is proposed, covering both non-isolated (buck, boost, etc.) and isolated (dual active bridge) DC-DC converters. Following this design method, resistive output impedance can be effectively obtained. On the other hand, hysteresis control is another way to further reduce output capacitance, since it features faster dynamic response than classical PID control. Herein, hysteresis controller is implemented on digital signal processors instead of field programmable gate arrays. The implementation details, including the generation of driving signals for power switches and the effect of non-negligible computation time, are presented.
The second aspect: second-order harmonic power is an unavoidable issue in DC microgrids with single-phase inverters/rectifiers. Since droop-controlled converters usually show low output impedance at twice the line frequency, second-order harmonic power can flow into resource sides of converters. In some application like fuel cells, such harmonic current ripples can shorten device lifetime. To prevent the diffusion of second-order harmonic power, this dissertation studies the adoption of notch filter and resonant regulator in control loops. Although these two methods could mitigate second-order harmonic current, they deteriorate the stability performance of converters. In such a case, modified notch filter and modified resonant regulator are proposed to overcome the shortcoming of the traditional schemes. A comparative study is carried out to highlight the advantages of the proposed filter and regulator.
The third aspect: there are two limitations of the traditional droop control: one limitation is that the output power of droop-controlled converters is determined by load condition, and the other one is that the power sharing performance of droop control degrades with the presence of interconnecting cable impedance. To enhance the power flexibility and accuracy, a power-based droop controller, which unifies power flow control and droop control, is proposed for resource converters. When grid-interfacing converters impose the DC bus voltage, resource converters could operate with power flow control. When grid-interfacing converters fail, resource converters could work with droop control to stabilize the system. Importantly, the switch from power flow control to droop control can be automatically accomplished without communication or detection schemes. The operation principle, the design criteria, and the power sharing performance of the proposed controller are analyzed comprehensively.
All of the above-mentioned proposals are verified by relevant experimental results performing on different laboratory-scale DC microgrid prototypes.
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Caldognetto, Tommaso. "Control of Electronic Power Converters for Low-Voltage Microgrids." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424527.
Full textAbstract:
The dissertation focuses on the management of master/slave microgrid architectures, where distributed energy resources (DERs) are interfaced to the grid by means of conventional current-driven power electronics interfaces and the microgrid is interfaced to the mains via a voltage-driven utility interface converter. The so called power-based control is proposed to regulate the contribution to microgrid needs from the energy resources that are available. The control approach ensures an accurate active and reactive power sharing among DERs that takes into account both local (i.e., DER level) and global (i.e., microgrid level) constraints. The described general approach to microgrid control is underpinned by the conservative power theory, which offers a meaningful, robust, and computationally efficient method to manage power quantities referring to different grid nodes.La tesi è focalizzata sulla gestione delle architetture di microrete di tipo master/slave, dove le risorse energetiche distribuite (DERs) sono connesse alla microrete per mezzo di convenzionali convertitori elettronici di interfaccia comandati in corrente mentre la microrete è interfacciata alla rete principale tramite un convertitore di interfaccia comandato in tensione. Il cosiddetto power-based control è utilizzato per regolare, al punto di saldo della microrete, il contributo di potenza da parte delle risorse energetiche disponibili. L'approccio di controllo garantisce un’accurata suddivisione del fabbisogno di potenza attiva e reattiva tra le DERs, tenendo conto di vincoli sia locali (i.e., a livello di DER) sia globali (i.e., a livello di microrete). L'approccio descritto per il controllo delle microreti si fonda sulla teoria conservativa delle potenze, la quale offre un metodo efficace, robusto e computazionalmente efficiente per la gestione di flussi di potenza controllabili attraverso nodi di rete distribuiti.
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Kazanbas, Mehmet [Verfasser]. "Analysis and Comparison of Power Electronic Converters with Electronic Isolation / Mehmet Kazanbas." Kassel : Kassel University Press, 2015. http://d-nb.info/1074489500/34.
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Kazanbas, Mehmet Cemil [Verfasser]. "Analysis and Comparison of Power Electronic Converters with Electronic Isolation / Mehmet Kazanbas." Kassel : Kassel University Press, 2015. http://nbn-resolving.de/urn:nbn:de:0002-38232.
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Elwakil, Ehab. "A new converter topology for high-speed high-starting-torque three-phase switched reluctance motor drive system." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/3009.
Full textAbstract:
Switched reluctance motor (SRM) has become a competitive selection for many applications of electric machine drive systems recently due to its relative simple construction and its robustness. The advantages of those motors are high reliability, easy maintenance and good performance. The absence of permanent magnets and windings in rotor gives possibility to achieve very high speeds (over 10000 rpm) and turned SRM into perfect solution for operation in hard conditions like presence of vibrations or impacts. Such simple mechanical structure greatly reduces its price. Due to these features, SRM drives are used more and more into aerospace, automotive and home applications. The major drawbacks of the SRM are the complicated algorithm to control it due to the high degree of nonlinearity, also the SRM has always to be electronically commutated and the need of a shaft position sensor to detect the shaft position, the other limitations are strong torque ripple and acoustic noise effects.
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Cha, Han Ju. "Analysis and design of matrix converters for adjustable speed drives and distributed power sources." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/1048.
Full textAbstract:
Recently, matrix converter has received considerable interest as a viable alternative to the conventional back-to-back PWM (Pulse Width Modulation) converter in the ac/ac conversion. This direct ac/ac converter provides some attractive characteristics such as: inherent four-quadrant operation; absence of bulky dc-link electrolytic capacitors; clean input power characteristics and increased power density. However, industrial application of the converter is still limited because of some practical issues such as common mode voltage effects, high susceptibility to input power disturbances and low voltage transfer ratio. This dissertation proposes several new matrix converter topologies together with control strategies to provide a solution about the above issues.
In this dissertation, a new modulation method which reduces the common mode voltage at the matrix converter is first proposed. The new method utilizes the proper zero vector selection and placement within a sampling period and results in the reduction of the common mode voltage, square rms of ripple components of input current and switching losses.
Due to the absence of a dc-link, matrix converter powered ac drivers suffer from input voltage disturbances. This dissertation proposes a new ride-through approach to improve robustness for input voltage disturbances. The conventional matrix converter is modified with the addition of ride-through module and the add-on module provides ride-through capability for matrix converter fed adjustable speed drivers.
In order to increase the inherent low voltage transfer ratio of the matrix converter, a new three-phase high-frequency link matrix converter is proposed, where a dual bridge matrix converter is modified by adding a high-frequency transformer into dc-link. The new converter provides flexible voltage transfer ratio and galvanic isolation between input and output ac sources.
Finally, the matrix converter concept is extended to dc/ac conversion from ac/ac conversion. The new dc/ac direct converter consists of soft switching full bridge dc/dc converter and three phase voltage source inverter without dc link capacitors. Both converters are synchronized for zero current/voltage switching and result in higher efficiency and lower EMI (Electro Magnetic Interference) throughout the whole load range. Analysis, design example and experimental results are detailed for each proposed topology.
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Kwak, Sangshin. "Design and analysis of modern three-phase AC/AC power converters for AC drives and utility interface." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2336.
Full textAbstract:
Significant advances in modern ac/ac power converter technologies and demands
of industries have reached beyond standard ac/ac power converters with voltage-source
inverters fed from diode rectifiers. Power electronics converters have been matured to
stages toward compact realization, increased high-power handling capability, and
improving utility interface. Modern ac/ac power converter topologies with various
control strategies have been introduced for the further improvements, such as matrix
converters, current-fed converters, PWM rectifiers, and active power filters. In this
dissertation, several new converter topologies are proposed in conjunction with
developed control schemes based on the modern ac/ac converters which enhance
performance and solve the drawbacks of conventional converters.
In this study, a new fault-tolerant PWM strategy is first proposed for matrix
converters. The added fault-tolerant scheme would strengthen the matrix converter
technology for aerospace and military applications. A modulation strategy is developed
to reshape output currents for continuous operation, against fault occurrence in matrix
converter drives.
This study designs a hybrid, high-performance ac/ac power converter for high
power applications, based on a high-power load commutated inverter and a mediumpower
voltage source inverter. Natural commutation of the load commutated inverter is
actively controlled by the voltage source inverter. In addition, the developed hybrid
system ensures sinusoidal output current/voltage waveforms and fast dynamic response
in high power areas.
A new topology and control scheme for a six-step current source inverter is
proposed. The proposed topology utilizes a small voltage source inverter, to turn off
main thyristor switches, transfer reactive load energy, and limit peak voltages across
loads. The proposed topology maximizes benefits of the constituent converters: highpower
handling capability of large thyristor-based current source inverters as well as fast
and easy control of small voltage source inverters.
This study analyzes, compares, and evaluates two topologies for unity power
factor and multiple ac/ac power conversions. Theoretical analyses and comparisons of
the two topologies, grounded on mathematical approaches, are presented from the
standpoint of converter kVA ratings, dc-link voltage requirements, switch ratings,
semiconductor losses, and reactive component sizes. Analysis, simulation, and
experimental results are detailed for each proposed topology.
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Prabhala, Venkata Anand Kishore. "Control and applications of double input DC-DC power electronic converters." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2010. http://scholarsmine.mst.edu/thesis/pdf/Prabhala_09007dcc807bbcfe.pdf.
Full textAbstract:
Thesis (M.S.)--Missouri University of Science and Technology, 2010.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 29, 2010) Includes bibliographical references (p. 95-100).
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Insleay, Allan. "Neural network applications in the control of power electronic converters." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ26003.pdf.
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Singh, Akanksha. "A boost current source inverter based generator-converter topology for direct drive wind turbines." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/34676.
Full textAbstract:
Doctor of PhilosophyDepartment of Electrical and Computer Engineering
Behrooz Mirafzal
In this dissertation, a new topology for Direct-Drive Wind Turbines (DDWTs) with a new power electronics interface and a low-voltage generator design is presented. In the presented power electronics interface, the grid - side converter is replaced by a boost Current Source Inverter (CSI) which eliminates the required dc-bus capacitors resulting in an increase in the lifetime of DDWTs. The inherently required dc-link inductor for this topology is eliminated by utilizing the inductance of the Permanent Magnet Synchronous Generator (PMSG). The proposed three-phase boost CSI is equipped with Reverse-Blocking IGBTs (RB-IGBT) and the Phasor Pulse Width Modulation (PPWM) switching pattern to provide a 98% efficiency and high boost ratios ([superscript V]LL/V[subscript dc]) up to 3.5 in a single stage. In this dissertation, Phasor Pulse Width Modulation (PPWM) pattern for the boost – CSI is also modified and verified through simulation and experimental results. In order to realize potential capabilities of the boost inverter and to assist its penetration into renewable energy systems, the boost inverter dynamic behaviors are studied in this dissertation. Then, the developed models are verified using circuit simulations and experiments on a laboratory-scale boost – CSI equipped with RB-IGBTs. The developed dynamic models are used to study the stability of the boost – CSI through root locus of small signal poles (eigenvalues) as control inputs and load parameters vary within the boost inverter's operating limits. The dynamic models are also used to design the control schemes for the boost – CSI for both stand-alone and grid-tied modes of operation. The developed controllers of the boost – CSI are verified through simulation and experimental results. In this dissertation, the boost – CSI steady-state characterization equations are also developed and verified. The developed boost – CSI is used to replace the grid - side converter in a DDWT. A reliability analysis on the power electronics interface of an existing and developed topology is presented to demonstrate the increase in the mean time between failures. The boost – CSI enables conversion of a low dc voltage to a higher line-to-line voltage enabling the implementation of a low-voltage generator. This further enables a reduction in the number poles required in DDWT generators. The feasibility of the presented low-voltage generator is investigated through finite element computations. In this dissertation, a 1.5MW low-voltage generator designed for the proposed topology is compared with an existing 1.5MW permanent magnet synchronous generator for DDWTs to demonstrate the reduction in the volume, weight, and amount of permanent magnet materials required in the generator. The feasibility of the developed system is supported by a set of MATLAB/Simulink simulations and laboratory experiments on the closed-loop stand-alone and grid-tied systems.
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Gezgin, Cahit. "Simultaneous control-structure optimization of power converters." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15796.
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Pirro, Matteo. "Embedded Control Systems for Performances Improvement and Energy Efficiency of Electrical Drives and Power Converters." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/243081.
Full textAbstract:
La domanda globale di energia elettrica è in continua crescita, al doppio del tasso di crescita del consumo di energia primaria. Un uso efficiente dell'energia, detto in altri termini "efficienza energetica", ha come obiettivo ridurre la quantità di energia richiesta per fornire i diversi prodotti e servizi.
Progressivamente diventerà obbligatoria per l'utente finale una sempre più chiara transizione dal combustibile primario verso sistemi di energia elettrica e l'efficienza energetica così come l'integrazione delle energie rinnovabili diventeranno una delle principali sfide del futuro. L'elettronica di potenza svolgerà un ruolo fondamentale nel cambiamento di questo paradigma. Nella generazione di energia elettrica vi sarà un importante migrazione alle fonti rinnovabili come future fonti energietiche. Nel campo dell'elettronica di potenza, quattro ambiti applicativi devono necessariamente essere presi in considerazione quando si parla di efficienza energetica: motori elettrici, convertitori di potenza, illuminazione a LED e HVDC.
In questa tesi è stata riportata una discussione dettagliata dei principali convertitori di potenza e sono state introdotte delle variazioni in alcuni modelli per rendere gli stessi più adatti alla rappresentazione del comportamento dei convertitori per particolari topologie o modalità di funzionamento.
Sono stati proposti e argomentati alcuni controllori basati su passività per la correzione del fattore di potenza; essi sono risultati particolarmente adatti a scenari applicativi come quello del controllo motori o dell'illuminazione a LED.
E' stato inoltre presentato un controllore PI basato su passività per il tracking globale valido per sistemi rappresentabili nella forma bilineare: particolarmente interessante è l'esempio applicativo riportato, relativo all'ambito del controllo HVDC.
Inoltre è stato elaborato un controllore sliding mode robusto alle variazioni di carico per la regolazione della tensione di uscita nei regolatori DC--DC.
Infine sono stati progettati degli osservatori di corrente per convertitori boost con l'obiettivo di rendere superfluo l'utilizzo dei costosi sensori di corrente in questa topologia.
Ciascun algoritmo è stato testato numericamente e la maggior parte di essi è stata anche implementata su piattaforme embedded e provata in laboratorio con l'obiettivo di verificarne e valutarne le prestazioni. Le prove sperimentali sono state effettuate nel Laboratorio di Robotica Avanzata del DII presso l'Università Politecnica delle Marche, Ancona, nel Laboratory of Energy Department presso il Supélec, Paris e nel Laboratoire de Signaux et Systémes presso il Supélec, Paris.The global demand for electrical energy is growing continuously, at double the growth rate of primary energy consumption. Efficient energy use, sometimes simply called energy efficiency, is the goal to reduce the amount of energy required to provide products and services. A clear transition to more electric energy systems is mandatory as energy efficiency from primary fuel to the enduser and the integration of renewables are the future key challenges. Power electronics will play a key role in this paradigm shift to more renewable electrical energy and higher energy efficiency in multiple applications. In electrical energy generation a major shift to renewables as sources of future electrical energy will happen. In the field of Power Electronics four topics must be taken into account talking about energy efficiency: electrical motors, power converters, LED lighting and HVDC. In this thesis a detailed discussion on the modelling of the most known power converters has been made and some more accurate models have been proposed to better represent the behaviour of particular topologies or working modes. Passivity-Based controllers for power factor control have been proposed and argued; they resulted particularly suited in the motor control and in the LED lighting applicative fields. A global tracking passivity–based PI controller for bilinear systems has been proposed: an example application has been presented in the field of HVDC control. Furthermore, a sliding-mode robust to load variations controller for output voltage regulation in DC--DC converters has been presented. Finally inductor current observers for the boost topology has been illustrated with the aim of making superfluous the use of expensive sensors in this topology. Each proposed algorithm has been numerically tested and many of them has been experimentally verified on embedded platforms and their performances evaluated. Experimental tests have been done in the Laboratory of Advanced Robotics of DII at Università Politecnica delle Marche, Ancona, in the Laboratory of Energy Department at Supélec, Paris and in the Laboratoire de Signaux et Systémes at Supélec, Paris.
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Chen, Hanling. "AVERAGE-VALUE MODELING OF HYSTERESIS CURRENT CONTROL IN POWER ELECTRONICS." UKnowledge, 2015. http://uknowledge.uky.edu/ece_etds/78.
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Hysteresis current control has been widely used in power electronics with the advantages of fast dynamic response under parameter, line and load variation and ensured stability. However, a main disadvantage of hysteresis current control is the uncertain and varying switching frequency which makes it difficult to form an average-value model. The changing switching frequency and unspecified switching duty cycle make conventional average-value models based on PWM control difficult to apply directly to converters that are controlled by hysteresis current control.
In this work, a new method for average-value modeling of hysteresis current control in boost converters, three-phase inverters, and brushless dc motor drives is proposed. It incorporates a slew-rate limitation on the inductor current that occurs naturally in the circuit during large system transients. This new method is compared with existing methods in terms of simulation run time and rms error. The performance is evaluated based on a variety of scenarios, and the simulation results are compared with the results of detailed models. The simulation results show that the proposed model represents the detailed model well and is faster and more accurate than existing methods. The slew-rate limitation model of hysteresis current control accurately captures the salient detail of converter performance while maintaining the computational efficiency of average-value models. Validations in hardware are also presented.
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Murray, Peter. "Harmonic modelling strategies for power electronic drives in electrically weak systems." Thesis, University of the West of Scotland, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361351.
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Junyent, Ferré Adrià. "Control of power electronic converters for the operation of wind generation." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/108501.
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The present PhD thesis analyzes the modelling and control of the two main topologies of large scale variable speed wind turbines, the doubly fed induction generator and the permanent magnet synchronous generator wind turbines, to operate under different types of voltage sags. The first part of the thesis deals with the modelling of the wind turbine from the mechanics to the different types of generators and the power converter. The second part deals with the control of the wind turbine. First, three different control schemes of the doubly fed induction machine are analyzed, starting with the most basic one, the conventional vector control meant for balanced operation which is simulated and compared to experimental measurements from a voltage sag test, and then moving to the dual synchronous reference frame and the stationary reference frame control, two different schemes that allow the operation of the machine under unbalanced voltage sags. Then, different reference calculation methods for the operation of grid connected voltage source converters under grid unbalances are analyzed and tested on a experimental platform. Finally, the vector control scheme of the permanent magnet synchronous generator and a ride-through strategy for this type of turbine for balanced voltage sags is presented and tested on a small scale experimental platform.Aquesta tesi analitza la modelització i el control per a l'operació sota diferents tipus de sots de tensió de les dues topologies més comunes d'aerogeneradors de velocitat variable de gran escala, la basada en generador d'inducció doblement alimentat i la de màquina síncrona d'imants permanents. La primera part de la tesi tracta el modelat de la turbina eòlica des de la mecànica fins als diferents tipus de generadors i el convertidor. La segona part tracta el control de l'aerogenerador. Primer, s'analitzen tres esquemes de control diferents de la màquina d'inducció doblement alimentada, començant pel tipus més bàsic, el control vectorial convencional, pensat per l'operació en equilibri, que és simulat i comparat amb mesures experimentals d'un assaig de sot de tensió, i tractant a continuació l'anomenat control vectorial amb doble referència de sincronisme i el control en referència estacionària, dos esquemes de control diferents que permeten l'operació de la màquina sota sots de tensió desequilibrats. A continuació s'analitzen i comproven experimentalment diferents mètodes de càlcul de referències pel control de convertidors amb font de tensió sota desequilibris de xarxa. Finalment, es presenta l'esquema de control vectorial de màquina síncrona d'imants permanents i una estratègia de ride-through per a aquest tipus d'aerogenerador que és avaluada en una plataforma experimental.
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Natsheh, Ammar Nimer. "Analysis, simulation and control of chaotic behaviour and power electronic converters." Thesis, Loughborough University, 2008. https://dspace.lboro.ac.uk/2134/5739.
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The thesis describes theoretical and experimental studies on the chaotic behaviour of a peak current-mode controlled boost converter, a parallel two-module peak current-mode controlled DC-DC boost converter, and a peak current-mode controlled power factor correction (PFC) boost converter. The research concentrates on converters which do not have voltage control loops, since the main interest is in the intrinsic mechanism of chaotic behaviour. These converters produce sub-harmonics of the clock frequency at certain values of the reference current I[ref] and input voltage V[in], and may behave in a chaotic manner, whereby the frequency spectrum of the inductor becomes continuous. Non-linear maps for each of the converters are derived using discrete time modelling and numerical iteration of the maps produce bifurcation diagrams which indicate the presence of subharmonics and chaotic operation. In order to check the validity of the analysis, MATLAB/SIMULINK models for the converters are developed. A comparison is made between waveforms obtained from experimental converters, with those produced by the MATLAB/SIMULINK models of the converters. The experimental and theoretical results are also compared with the bifurcation points predicted by the bifurcation diagrams. The simulated waveforms show excellent agreement, with both the experimental waveforms and the transitions predicted by the bifurcation diagrams. The thesis presents the first application of a delayed feedback control scheme for eliminating chaotic behaviour in both the DC-DC boost converter and the PFC boost converter. Experimental results and FORTRAN simulations show the effectiveness and robustness of the scheme. FORTRAN simulations are found to be in close agreement with experimental results and the bifurcation diagrams. A theoretical comparison is made between the above converters controlled using delayed feedback control and the popular slope compensation method. It is shown that delayed feedback control is a simpler scheme and has a better performance than that for slope compensation.
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Wan, Kai. "Advanced current-mode control techniques for DC-DC power electronic converters." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Wan_09007dcc80642d38.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 4, 2009) Includes bibliographical references.
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Glaser, John Stanley 1964. "Topics in large-signal behavior of power electronic converters and systems." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282217.
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A variety of topics in large-signal and system-level power electronics are explored. First, the load-sharing problem for converters with parallel- and series-connected outputs is defined and explained. Requirements for load-sharing behavior are illustrated graphically. Many classes of switching converters are capable of load-sharing aside from current-programmed-mode (CPM) converters, including but not limited to discontinuous-mode (DCM) pulse-width-modulated (PWM) converters and resonant converters. The input filter problem is studied for high-power-factor rectifiers (HPFRs) based on the DCM flyback converter. Such HPFRs require an input filter to reduce switching noise conducted to the AC line, but the filter can degrade the power factor and interfere with converter operation. The analysis allows filter design that minimizes and balances these effects. Intuitive and analytical approaches are given and compared. The analytical approach uses phase plane methods usually used for resonant converter analysis. Although the filter design is for a specific converter, the approach is applicable to any HPFR. A single-quadrant negative resistor is synthesized from a DCM flyback converter. This circuit is simple, efficient, and can handle power levels over 100W. A design procedure and small-signal analysis are given. Additionally, a set of large-signal dynamic circuit models are presented for DCM PWM converters. A general impedance synthesizer is developed based on a four-quadrant switching converter. This circuit is used to create the negative resistance pseudoinverter, which puts power onto the AC line for sale to a utility. To develop the pseudoinverter, the concept of load reduction is employed. Potential stability problems are studied and a solution implemented. The synthesis of self-contained reactive components is also studied. Extensive experimental verification substantiates the majority of the concepts in this dissertation. Simulation is also used to support some of the analysis.
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Colmenares, Juan. "Extreme Implementations of Wide-Bandgap Semiconductors in Power Electronics." Doctoral thesis, KTH, Elkraftteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192626.
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Wide-bandgap (WBG) semiconductor materials such as silicon carbide (SiC) and gallium-nitride (GaN) allow higher voltage ratings, lower on-state voltage drops, higher switching frequencies, and higher maximum temperatures. All these advantages make them an attractive choice when high-power density and high-efficiency converters are targeted. Two different gate-driver designs for SiC power devices are presented. First, a dual-function gate-driver for a power module populated with SiC junction field-effect transistors that finds a trade-off between fast switching speeds and a low oscillative performance has been presented and experimentally verified. Second, a gate-driver for SiC metal-oxide semiconductor field-effect transistors with a short-circuit protection scheme that is able to protect the converter against short-circuit conditions without compromising the switching performance during normal operation is presented and experimentally validated. The benefits and issues of using parallel-connection as the design strategy for high-efficiency and high-power converters have been presented. In order to evaluate parallel connection, a 312 kVA three-phase SiC inverter with an efficiency of 99.3 % has been designed, built, and experimentally verified. If parallel connection is chosen as design direction, an undesired trade-off between reliability and efficiency is introduced. A reliability analysis has been performed, which has shown that the gate-source voltage stress determines the reliability of the entire system. Decreasing the positive gate-source voltage could increase the reliability without significantly affecting the efficiency. If high-temperature applications are considered, relatively little attention has been paid to passive components for harsh environments. This thesis also addresses high-temperature operation. The high-temperature performance of two different designs of inductors have been tested up to 600_C. Finally, a GaN power field-effect transistor was characterized down to cryogenic temperatures. An 85 % reduction of the on-state resistance was measured at −195_C. Finally, an experimental evaluation of a 1 kW singlephase inverter at low temperatures was performed. A 33 % reduction in losses compared to room temperature was achieved at rated power.QC 20160922
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Sadik, Diane-Perle. "On Reliability of SiC Power Devices in Power Electronics." Doctoral thesis, KTH, Elkraftteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207763.
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Silicon Carbide (SiC) is a wide-bandgap (WBG) semiconductor materialwhich has several advantages such as higher maximum electric field, lowerON-state resistance, higher switching speeds, and higher maximum allowablejunction operation temperature compared to Silicon (Si). In the 1.2 kV - 1.7kV voltage range, power devices in SiC are foreseen to replace Si Insulatedgatebipolar transistors (IGBTs) for applications targeting high efficiency,high operation temperatures and/or volume reductions. In particular, theSiC Metal-oxide semiconductor field-effect transistor (MOSFET) – which isvoltage controlled and normally-OFF – is the device of choice due to the easeof its implementation in designs using Si IGBTs.In this work the reliability of SiC devices, in particular that of the SiCMOSFET, has been investigated. First, the possibility of paralleling two discreteSiC MOSFETs is investigated and validated through static and dynamictests. Parallel-connection was found to be unproblematic. Secondly, drifts ofthe threshold voltage and forward voltage of the body diode of the SiC MOSFETare investigated through long-term tests. Also these reliability aspectswere found to be unproblematic. Thirdly, the impact of the package on thechip reliability is discussed through a modeling of the parasitic inductancesof a standard module and the impact of those inductances on the gate oxide.The model shows imbalances in stray inductances and parasitic elementsthat are problematic for high-speed switching. A long-term test on the impactof humidity on junction terminations of SiC MOSFETs dies and SiCSchottky dies encapsulated in the same standard package reveals early degradationfor some modules situated outdoors. Then, the short-circuit behaviorof three different types (bipolar junction transistor, junction field-effect transistor,and MOSFET) of 1.2 kV SiC switching devices is investigated throughexperiments and simulations. The necessity to turn OFF the device quicklyduring a fault is supported with a detailed electro-thermal analysis for eachdevice. Design guidelines towards a rugged and fast short-circuit protectionare derived. For each device, a short-circuit protection driver was designed,built and validated experimentally. The possibility of designing diode-lessconverters with SiC MOSFETs is investigated with focus on surge currenttests through the body diode. The discovered fault mechanism is the triggeringof the npn parasitic bipolar transistor. Finally, a life-cycle cost analysis(LCCA) has been performed revealing that the introduction of SiC MOSFETsin already existing IGBT designs is economically interesting. In fact,the initial investment is saved later on due to a higher efficiency. Moreover,the reliability is improved, which is beneficial from a risk-management pointof-view. The total investment over 20 years is approximately 30 % lower fora converter with SiC MOSFETs although the initial converter cost is 30 %higher.Kiselkarbid (SiC) är ett bredbandgapsmaterial (WBG) som har flera fördelar,såsom högre maximal elektrisk fältstyrka, lägre ON-state resitans, högreswitch-hastighet och högre maximalt tillåten arbetstemperatur jämförtmed kisel (Si). I spänningsområdet 1,2-1,7 kV förutses att effekthalvledarkomponenteri SiC kommer att ersätta Si Insulated-gate bipolar transistorer(IGBT:er) i tillämpningar där hög verkningsgrad, hög arbetstemperatur ellervolymreduktioner eftersträvas. Förstahandsvalet är en SiC Metal-oxidesemiconductor field-effect transistor (MOSFET) som är spänningsstyrd ochnormally-OFF, egenskaper som möjliggör enkel implementering i konstruktionersom använder Si IGBTer.I detta arbete undersöks tillförlitligheten av SiC komponenter, specielltSiC MOSFET:en. Först undersöks möjligheten att parallellkoppla tvådiskretaSiC MOSFET:ar genom statiska och dynamiska prov. Parallellkopplingbefanns vara oproblematisk. Sedan undersöks drift av tröskelspänning ochbody-diodens framspänning genom långtidsprov. Ocksådessa tillförlitlighetsaspekterbefanns vara oproblematiska. Därefter undersöks kapslingens inverkanpåchip:et genom modellering av parasitiska induktanser hos en standardmoduloch inverkan av dessa induktanser pågate-oxiden. Modellen påvisaren obalans mellan de parasitiska induktanserna, något som kan varaproblematiskt för snabb switchning. Ett långtidstest av inverkan från fuktpåkant-termineringar för SiC-MOSFET:ar och SiC-Schottky-dioder i sammastandardmodul avslöjar tidiga tecken pådegradering för vissa moduler somvarit utomhus. Därefter undersöks kortslutningsbeteende för tre typer (bipolärtransistor,junction-field-effect transistor och MOSFET) av 1.2 kV effekthalvledarswitchargenom experiment och simuleringar. Behovet att stänga avkomponenten snabbt stöds av detaljerade elektrotermiska simuleringar för allatre komponenter. Konstruktionsriktlinjer för ett robust och snabbt kortslutningsskyddtas fram. För var och en av komponenterna byggs en drivkrets medkortslutningsskydd som valideras experimentellt. Möjligheten att konstrueradiodlösa omvandlare med SiC MOSFET:ar undersöks med fokus påstötströmmargenom body-dioden. Den upptäckta felmekanismen är ett oönskat tillslagav den parasitiska npn-transistorn. Slutligen utförs en livscykelanalys(LCCA) som avslöjar att introduktionen av SiC MOSFET:ar i existerandeIGBT-konstruktioner är ekonomiskt intressant. Den initiala investeringensparas in senare pågrund av en högre verkningsgrad. Dessutom förbättrastillförlitligheten, vilket är fördelaktigt ur ett riskhanteringsperspektiv. Dentotala investeringen över 20 år är ungefär 30 % lägre för en omvandlare medSiC MOSFET:ar även om initialkostnaden är 30 % högre.
QC 20170524
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Loh, Poh Chiang 1973. "A universal flux/charge modulation strategy for three-phase power electronic converters." Monash University, Dept. of Electrical and Computer Systems Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/8087.
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Du, Toit J. A. (Jacques Andre). "Development and analysis of a distributed control strategy for power electronic converters." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52761.
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Thesis (PhD)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: The dissertation presents an alternative approach to the control of power electronic converters. The conventional approach is to use a centralized controller with one or more measurement systems providing feedback. As converters become larger, in both power rating and complexity, a number of drawbacks to this approach emerge. The number of physical data paths increases and voltage isolation becomes a problem. This has an adverse effect on the manufacturability as well as the reliable operation of the system as a whole. An alternative is to use a distributed control approach, where a number of smaller integrated control and measurement units are used. These units communicate with the central controller via a serial daisy-chain communications link. The dissertation investigates the design of such a controller as well as the application of distributed control in a number of emerging converter topologies. It was shown that centralized control has its limitations in modem power electronics in terms of reliability, maintainability and manufacturability. A feasible distributed control strategy was proposed and implemented and the operation was verified in an experimental converter system.
AFRIKAANSE OPSOMMING: Die proefskrif ondersoek 'n alternatiewe manier om drywings omsetters te beheer. Huidiglik word die meerderheid van omsetters beheer vanaf 'n sentrale beheereenheid, wat dan stelsel data versamel vanaf een of meer meetstelsels. Soos die drywingsvermoë van die omsetters toeneem, raak spannings isolasie en die aantal beheerseine 'n probleem, wat nadelig is vir die betroubaarheid en vervaardigbaarheid van die stelsel. As 'n alternatief, kan 'n aantal kleiner beheereenhede en meetstelsels gebruik word. Die beheerders kommunikeer met mekaar, sowel as die hoof stelselbeheerder deur middel van 'n optiese vesel netwerk, verbind in 'n ring struktuur. Die proefskrif ondersoek die ontwerp van die beheerder en die toepassing van gedesentraliseerde beheer in 'n aantal nuwe omsetter topologië. Die studie toon dat sentrale beheer problematies kan raak soos die omsetters meer kompleks raak. Die studie bewys dat 'n stelsel suksesvol bedryf kan word deur gebruik te maak van gedesentraliseerde beheer deur dit in 'n praktiese opstelling toe te pas.
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Samavatian, Vahid. "A Systematic Approach to Reliability Assessment of DC-DC Power Electronic Converters." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT028.
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La fiabilité et la sureté de fonctionnement de l'électronique de puissance jouent un rôle majeur aujourd'hui dans l'industrie. Cette thèse propose un nouveau cadre d'étude de la fiabilité à partir de deux méthodes afin d'améliorer la précision des études de fiabilité : une analyse utilisant la méthode des système dégradés multi état, et une analyse par intervalles. La considération des effets de dégradation propres et couplés de chaque composant est également une problématique qu'il reste aujourd'hui à étudier et qui est traitée dans ce travail.L'étude de la fiabilité par intervalles permet d'estimer des intervalles de durée de vie des convertisseurs DC/DC en prenant en compte les dégradations propres et mutuelles des composants. Fondamentalement, cette méthode est basée sur la compréhension des phénomènes physiques. A partir de cette méthode, on peut obtenir un intervalle pour la durée de vie d'un système complet. Cette méthode n'est toutefois pas adaptée aux systèmes redondants.De son côté, la fiabilité des systèmes dégradés multi-états est capable de proposer une étude au niveau système en prenant en compte le profil de mission et la physique des dégradations. Cette méthode a été généralisée dans cette thèse au procédés subissant de multiples dégradations.L'exemple d'un convertisseur DC/DC conprenant trois composants critiques a été étudié comme cas d'application. Deux composants semiconducteurs, diode et IGBT, et un condensateur sont considérés comme trois process de dégradation et l'effet de leur vieillissement sur la durée de vie du convertisseur est discutée. Le convertisseur étudié a pour puissance 3 kW (200/400V) et est dédié aux applications de type véhicule électrique. Il subit un profil de mission typique automobile (cycle WLTP)Reliable and unceasing exploitation of power electronic converters plays a major part in every application. This PhD thesis comes up with new opened-up reliability assessment frameworks and demonstrates the feasibility of using multistate degraded system analysis and interval analysis as well for attaining much more accuracy in reliability evaluation. Considering self- and coupling degradation effects of the items and assessing reliability in the system level are important issues which are still lacking in the previous studies and the present thesis has made an effort to overcome these problems. The thesis tries to launch two distinct reliability assessment frameworks, namely interval reliability and Multistate degraded system reliability.Interval reliability is capable of introducing an interval useful lifetime for DC-DC power electronic converters in which the self and coupling degradations effects of items have been taken into account. Fundamentally, it is based on the conventional physics of failure reliability assessment. Based on this method, instead of obtaining an inaccurate reliability value, one can attain an interval for the reliability of a global system whose useful lifetime undoubtedly lays between the boundaries. This method is able to consider degradation dependencies and assess multi-component system level reliability but not redundant system. An attempt was made to enhance the conventional reliability framework to reach a systematic approach capable of estimating a reliability assessment considering self and mutual degradation effects and being able to evaluate system-level reliability including redundant system. Multistate degraded system reliability analysis is capable of estimating system-level reliability, while mission profile and physics of failure of the system’s items are taken into account. In addition, the self and mutual degradation effects of items on the operation of the global system have been considered. The multi-state degraded system reliability model exposed to multiple failure processes has been generalized. The operating condition of the global system is defined by a finite number of states. Not only can the proposed framework be employed in determining the reliability of the degraded systems in terms of multi-state functions, but also it can obtain the states of the systems by estimating the system state probabilities.As an application, a DC-DC power electronic system containing three critical items has been studied. In this case study, two power semiconductors, namely IGBT and diode, and a power capacitor have been considered as three degradation processes and their aging effects on the useful lifetime estimation of the power electronic system have been discussed. For having a sense about newly proposed reliability frameworks, a 3000W and 200/400 V conventional DC-DC converter for electric vehicle application exposed to WLTP driving cycle is considered
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Bakar, Muhammad Abu. "Design and optimization of soft switched power converters for low and medium power applications." Licentiate thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-29801.
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Vid tidpunkten för seminariet var följande delarbeten opublicerade: delarbete 4 under granskning.
At the time of the licentiate seminar the following papers were unpublished: paper 4 under review.
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Sandells, David William. "Investigation into chain-cell converters and their use within power systems." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289841.
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Am, Sokchea. "Power modules design and optimization for medium power of MMC inverters : high insulation voltage gate driver system and 3D packaging." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT095/document.
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Dans cette recherche, l'auteur met l'accent à la fois sur une optimisation de la conception pour une (MV-MMC: Medium Voltage Modular Multilevel Converter) utiliser comme un DC/AC ou AC/DC et à deuxième fois sur la grille pour les modules IGBT qui sont utilisés dans ce type d'application. Par exemple, les convertisseurs de MMC sont utilisés dans les systèmes d'alimentation des navires électriques avec les buses de moyenne tension de courant continu (en anglais: medium-voltage direct current (MVDC)). Pour une telle application, selon le document IEEE, la tension du bus DC peut être jusqu'à 35kV. Par conséquent, les systèmes de commande rapprochée pour piloter le grille des modules IGBT pour les applications MVDC-MMC sont des principaux problèmes en termes d'architectures et des besoins de haute isolation galvanique. Ainsi, cette thèse fournit des solutions pour répondre à ces problèmes. L'étude inclut également les études d'un matériau diélectrique qui est utilisé comme matériau d'isolation. Les résultats des essais expérimentaux d'un matériau diélectrique proposé pour différentes épaisseurs des couches pour maintenir des niveaux de tension d'isolation sont également fournis pour valider clairement cette étude. En effet, un convertisseur MMC compose d'un certain nombre de cellules de conversion connectés en série. Une cellule (sous-module de convertisseur) est classiquement constitué de deux modules IGBT. Sur la base de la topologie de la cellule, l'architecture d'un pilote de grille contestée pour les modules de puissance à semi-conducteurs est proposée et comparée à celle classique en termes de besoins des niveaux de tension d'isolation galvanique, la taille de la cellule de convertisseur, etcIn this research, the author focuses on both a design optimization for a Medium Voltage Modular Multilevel Converter (MV-MMC) use as a DC/AC or AC/DC converter and gate drivers systems for IGBT modules which are used in this kind of application. For example, the MMC converters are used in Medium-Voltage Direct Current (MVDC) electrical ship power systems. For such application, according to IEEE document, the DC bus voltage can be up to 35kV. Hence, gate drivers’ systems for IGBT modules for MVDC-MMC applications are major concerns in terms of architectures and insulation voltage capabilities. Thus, this dissertation provides solutions to answer these problems. The study also includes the studies of a dielectric material which is used as insulation material. The results of experimental tests of a proposed dielectric material for different layers thicknesses to sustain different insulation voltage levels are also provided to clearly validate this study. Actually, a MMC converter composes of a number of converter cells connected in series. One cell (converter’s sub-module) is classically composed of two IGBT modules. Based on the cell topology, a challenged gate driver’s architecture for power semiconductor modules is proposed and compared to the classical one in terms of high and low galvanic insulation voltage levels’ requirements, converter’s cell size, etc