A monolithically integrated smart rectifier has been presented first in this work. The smart rectifier, which integrates a power MOSFET, gate driver and control circuitry, operates in a self-synchronized fashion based on its drain-source voltage, and does not need external control input. The analysis, simulation, and design considerations are described in detail. A 5V, 5-µm CMOS process was used to fabricate the prototype. Experimental results show that the proposed rectifier functions as expected in the design. Since no dead-time control needs to be used to switch the sync-FET and ctrl-FET, it is expected that the body diode losses can be reduced substantially, compared to the conventional synchronous rectifier. The proposed self-synchronized rectifier (SSR) can be operated at high frequencies and maintains high efficiency over a wide load range. As an example of the smart rectifier's application in isolated DC-DC converter, a synchronous flyback converter with SSR is analyzed, designed and tested. Experimental results show that the operating frequency could be as high as 4MHz and the efficiency could be improved by more than 10% compared to that when a hyper fast diode rectifier is used. Based on a new current-source gate driver scheme, an integrated gate driver for buck converter is also developed in this work by using a 0.35µm CMOS process with optional high voltage (50V) power MOSFET. The integrated gate driver consists both the current-source driver for high-side power MOSFET and low-power driver for low-side power iv MOSFET. Compared with the conventional gate driver circuit, the current-source gate driver can recovery some gate charging energy and reduce switching loss. So the current-source driver (CSD) can be used to improve the efficiency performance in high frequency power converters. This work also presents a new implementation of a power supply in package (PSiP) 5MHz buck converter, which is different from all the prior-of-art PSiP solutions by using a high-Q bondwire inductor. The high-Q bondwire inductor can be manufactured by applying ferrite epoxy to the common bondwire during standard IC packaging process, so the new implementation of PSiP is expected to be a cost-effective way of power supply integration.

This thesis investigates the feasibility of using Silicon Carbide (SiC)-based multiphase inverters (MPIs) for transportation electrification applications. The research begins with a comprehensive review on the state-of-the-art of MPIs, focusing on voltage source inverters (VSIs) and nine-switch inverters (NSIs), with five-, six-, and nine-phase configurations. The quantitative and qualitative analyses demonstrate that the six-phase VSI is the most promising topology, offering reduced DC-capacitor requirements, lower cabling cost, and higher fault tolerance capability while maintaining the same efficiency and power device count of a three-phase VSI. The feasibility of the SiC-based six-phase inverter is further investigated at the vehicle level, where a vehicle model is developed to study the energy consumption under different drive cycles. The resulting indicate an 8% improvement in vehicle mileage and fuel economy of the SiC-based six-phase inverter compared to its Si-based counterpart. This thesis also examines the current and voltage stresses on the DC-bus capacitor in two-level six-phase VSIs. The study considers two configurations of load/winding spatial distribution: symmetric and asymmetric. Consequently, analytical formulas for the DC-bus capacitor current and voltage ripples are derived. Furthermore, simple capacitor sizing rules in six-phase VSIs with different load configurations are provided. The accuracy of the derived formulas is verified by simulation and experimental testing, and their boundary conditions are identified. Six-phase VSI supplying symmetric loads was found to yield the smallest capacitor size. Based on the foregoing technology review and analyses, a holistic design methodology for a 100 kW SiC-based six-phase traction inverter for an electric vehicle application is presented. The proposed methodology considers the device power level, where discrete SiC MOSFETs are utilized, and the DC-capacitor sizing, where a multi-objective optimization algorithm is proposed to find the most suitable capacitor bank. Mechanical and thermal design constraints are also explored to deliver a compact housing with an integrated coolant channel. The resultant inverter design from the proposed electrical-thermal-mechanical design methodology is prototyped and experimentally tested, demonstrating a 7% reduction in DC-capacitor volume and 21% reduction in cabling cost when compared to conventional three-phase inverters of the same volt-ampere rating. The peak power density of the prototype inverter is 70 kW/L, demonstrating a compact design. Besides, the proposed design is benchmarked against commercial six-phase inverter models, whereby the competitiveness of the proposed design is highlighted. Finally, the unique control aspects of six-phase electric motor drives are investigated to identify suitable controls strategies for various operating conditions. The study places special emphasis on high-speed operation and evaluates several overmodulation techniques. An adaptive flux-weakening control algorithm is also proposed for the six-phase motor drive, which significantly improves the DC-bus voltage utilization of the inverter when used in conjunction with overmodulation. Overall, this thesis provides a comprehensive study of SiC-based six-phase traction inverters and proposes a holistic design methodology that considers electrical, thermal, and mechanical aspects. The results demonstrate the feasibility and advantages of SiC-based six-phase traction inverters for electric vehicle applications. / Thesis / Doctor of Philosophy (PhD) / Electric cars are continuously challenged to meet regulatory mandates that become stricter by the day. This is driven by the need for a clean, reliable, affordable, and sustainable transportation system. In this research, a novel, more reliable, and cost-effective power control unit (PCU) is proposed. The PCU manages the power flow regulation between the battery and the motor(s). The proposed PCU employs the same number of devices as a traditional counterpart, yet in a more modular architecture that doubles the safety factor compared to the standard design. In fault scenarios where the traditional PCU would fail, the proposed PCU would continue operating at half power, allowing the driver and passengers to reach a safe destination before the car is repaired. Extensive analyses were undertaken to identify an optimal design in terms of performance, size, and cost. Then, an engineering prototype is constructed and tested on an electric drivetrain testbed. Finally, the prototype is benchmarked against commercial competitors in the market to establish its economical feasibility.

No description available.

No description available.

No description available.

With worldwide growing demand for electric energy, there has been a great interest in exploring photovoltaic (PV) sources. For the PV generation system, the power converter is the most essential part for the efficiency and function performance. In recent years, there have been quite a few new transformerless PV inverters topologies, which eliminate the traditional line frequency transformers to achieve lower cost and higher efficiency, and maintain lower leakage current as well. With an overview of the state-of-the-art transformerless PV inverters, a new inverter technology is summarized in the Chapter 2, which is named V-NPC inverter technology. Based this V-NPC technology, a family of high efficiency transformerless inverters are proposed and detailly analyzed. The experimental results demonstrate the validity of V-NPC technology and high performance of the transformerless inverters. For the lower power level transformerless inverters, most of the innovative topologies try to use super junction metal oxide semiconductor field effect transistor(MOSFET) to boost efficiency, but these MOSFET based inverter topologies suffer from one or more of these drawbacks: MOSFET failure risk from body diode reverse recovery, increased conduction losses due to more devices, or low magnetics utilization. By splitting the conventional MOSFET based phase leg with an optimized inductor, Chapter 3 proposes a novel MOSFET based phase leg configuration to minimize these drawbacks. Based on the proposed phase leg configuration, a high efficiency single-phase MOSFET transformerless inverter is presented for the PV micro-inverter applications. The PWM modulation and circuit operation principle are then described. The common mode and differential mode voltage model is then presented and analyzed for circuit design. Experimental results of a 250 W hardware prototype are shown to demonstrate the merits of the proposed MOSFET based phase-le and the proposed transformerless inverter. New codes require PV inverters to provide system regulation and service to improve the distribution system stabilization. One obvious impact on PV inverters is that they now need to have reactive power generation capability. The Chapter 4 improves the MOFET based transformerless inverter in the Chapter 3 and proposed a novel pulse width modulation (PWM) method for reactive power generation. The ground loop voltage of this inverter under the proposed PWM method is also derived with common mode and differential mode circuit analyses, which indicate that high-frequency voltage component can be minimized with symmetrical design of inductors. A 250-W inverter hardware prototype has been designed and fabricated. Steady state and transient operating conditions are tested to demonstrate the validity of improved inverter and proposed PWM method for reactive power generation, high efficiency of the inverter circuit, and the high-frequency-free ground loop voltage. Besides the high efficiency inverter circuit, the grid connection function is also the essential part of the PV system. The Chapter 5 present the overall function blocks for a grid-connected PV inverter system. The current control and voltage control loop is then analyzed, modeled, and designed. The dynamic reactive power generation is also realized in the control system. The new PLL method for the grid frequency/voltage disturbance is also realized and demonstrate the validity of the detection and protection capability for the voltage/frequency disturbance. At last, a brief conclusion is given in the Chapter 6 about each work. After that, future works on device packaging, system integration, innovation on inverter circuit, and standard compliance are discussed. / Ph. D.

The demand for high-power converters are surging due to applications like renewable energy, motor drives and grid-interface applications. Typically, these converters’ power ranges from tens of kilowatts (kW) to several megawatts (MW). To reach such high power levels the converter voltage ratings must increase, as the current ratings cannot be reached by the available devices or because the system losses become excessive. To address this, two strategies can be utilized: multilevel topologies (e.g. Multilevel Modular Converter or Flying Capacitor Multilevel Converter) and high voltage switches. For medium voltage applications, the most commonly employed switches are the IGBT and the IGCT. Both are silicon-based technology and are limited to a rated voltage of 6.5 kV and 4.5 kV, respectively. Often, these devices switching frequency are limited to less than 1 kHz. To expand the frontiers of medium voltage converters and to demonstrate the capabilities of wide band gap devices in medium voltage, a 7-level 13.8 kV AC 22 kV DC 1.1 MW flying capacitor multilevel converter based on 10 kV SiC MOSFET with 2.5 kHz switching frequency was designed and constructed. Given the complexity of a multilevel topology, the high voltage levels, and the critical nature of the loads, a failure in a high-power converter can incur significant costs, long service downtime, and safety risks to personnel. Hence, understanding the failure modes of these converters is essential for designing protections and mitigation strategies to prevent or reduce the risks of failures. Furthermore, the adoption of 10 kV SiC MOSFET introduces additional challenges in terms of protection. Despite their well-known benefits, these devices exhibit shorter energy withstanding time compared with their silicon counterpart, and increased insulation stress resulting from the high dv/dt imposed by the fast-switching transient at higher voltages. In this context, a failure mode analysis was conducted for the converter aforementioned. The analysis examined the fault dynamics and evaluated the protections schemes at the converter level. The study identified a failure mechanism between cells, so called Cell Short- Circuit Fault (CSCF), capable of damaging the entire phase-leg. In response, a protection scheme based on TVS (Transient Voltage Suppression) diodes was designed to prevent extremely imbalanced cell voltages and failure propagation. Because of the high electric field intensity environment of the converter, an FEA (Finite Element Analyses) simulation is performed to verify and control the electric field (E-field) intensity within the protection module itself and in the converter assembly. Next, the protection module insulation design was successfully verified in a Partial Discharge (PD) experiment. In sequence, an experimental verification utilizing an equivalent circuit based on the fault model demonstrated the efficacy of the protection module. Waveforms extracted while the converter was operating showing the protection module acting during a fault are presented and analyzed. Finally, the influence of the protection module in the switching of the 10 kV SiC MOSFET was evaluated via a double pulse test (DPT), revealing negligible effects on the converter performance. / Center of Power Electronics Systems (CPES) Department of Energy (DoE) / Master of Science / Due to governmental policies and market opportunities renewable energy (e.g. solar and wind energy) is increase its share in the electricity generation in the US and around the world. This scenario poses challenges regarding the stability of the grid and variation in the generation along the day. One of the alternatives to alleviate the problem is to use highpower converters that provides a interface between grid and manufacturing plants. This type of converter have bidirectional capabilities and can store the energy generated by solar farms during the day and return it to the grid at night for example. Moreover, it can provide grid support capabilities in terms of variation of frequency and voltage. To expand on the grid interface converters application concept, a medium voltage power converter in 22 kV DC and 13.8 kV AC is designed utilizing novel techniques and the latest technologies in semiconductors, 10 kV SiC MOSFETs. The benefits of this design are a small form factor, high efficiency, immunity to electromagnetic interference and power quality. This work presents a failure mode analysis of the power converter aforementioned, the analysis examined the fault dynamics and an evaluation of the protections schemes at the converter level. The failure analysis revealed the need of a protection scheme extremely imbalanced cell voltages and failure propagation. Hence, a protection module based on TVS (Transient Voltage Suppression) diodes was successfully designed and tested. Due to the high voltages present in this equipment, an FEA (Finite Element Analyses) simulation is performed to verify and control the electric field (E-field) intensity within the protection module itself and in the converter assembly. Experimental results are provided for insulation design integrity (partial discharge test), for the efficacy of the protection module against the fault, and for the impact of the protection module on the operation performance.

Diploma thesis describes the design of an switched mode power supply with switching at zero voltage for driving the anode of Anode-layer type ion source. First aim of thesis is ion sources and specialy Anode-layer type of ion source in detail. Main aim of thesis are important aspects of the design of switching mode power supply, which comes later the detailed construction of an switched mode power supply with output voltage 2800 V at output power 2800 W.

Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη, το σχεδιασμό, την πρσοομοίωση και την κατασκευή κυκλώματος για την οδήγηση και τον έλεγχο στροφών κινητήρα τύπου DC Brushless.Η εργασία αυτή εκπονήθηκε στο εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Ηλεκτρονικών Υπολογιστών. Σκοπός της παρούσας εργασίας είναι η μελέτη και η κατασκευή κυκλώματος τριφασικού αντιστροφέα ισχύος για να επιτύχουμε οδήγηση και έλεγχο κινητήρα τύπου DC Brushless. Ο κινητήρας αυτού του τύπου είναι Σύγχρονος κινητήρας Μόνιμου Μαγνήτη. Για το λόγο αυτό το πρώτο πράγμα που μελετήθηκε στην παρούσα εργασία είναι κάποιες θεμελιώδεις ιδιότητες του μαγνητικού πεδίου, καθώς και τα χαρακτηριστικά των μαγνητικών υλικών που χρησιμοποιούνται σε τέτοιους τύπους κινητήρων. Στην συνέχεια αναλύονται οι κινητήρων Brushless DC ως προς την κατασκευή τους καθώς και τη λειτουργία τους. Παρατίθενται οι εξισώσεις που περιγράφουν τη λειτουργία τους και οι χαρακτηριστικές ροπής-ταχύτητας και επιπλέον γίνεται σύγκριση αυτών με κινητήρες άλλων τύπων. Ακολουθεί η περιγραφή της προσομοίωσης του συστήματος η οποία πραγματοποιήθηκε στο πρόγραμμα προσομοίωσης ηλεκτρικών κυκλωμάτων Simulink του Matlab. Αναλύεται η λογική στην οποία βασιστήκαμε για την προσομοίωση και παρατίθενται οι κυματομορφές της τάσης και του ρεύματος σε διάφορα σημεία του κυκλώματος. Έπειτα γίνεται μια θεωρητική ανάλυση του κυκλώματος του αντιστροφέα που κατασκευάστηκε καθώς και όλων των άλλων κυκλωμάτων και στοιχείων που απαιτήθηκαν για τη λειτουργία της διάταξης. Επιπλέον περιγράφεται η μέθοδος παλμοδότησης που χρησιμοποιήθηκε για την έναυση/σβέση των διακοπτικών στοιχείων ισχύος. Τέλος γίνεται αναλυτική παράθεση του τελικού κυκλώματος που κατασκευάστηκε. Προχωράμε με την περιγραφή των ιδιοτήτων και δυνατοτήτων του μικροελεγκτή που χρησιμοποιήθηκε στην πλακέτα μας, καθώς επίσης και με τη λογική που ακολουθήθηκε κατά τον προγραμματισμό του. Τέλος παραθέτονται τα αποτελέσματα των πειραμάτων και τα παλμογραφήματα που ελήφθησαν κατά τη διεξαγωγή τους. Γίνεται σχολιασμός των αποτελεσμάτων αυτών και αξιολόγηση της κατασκευής. / This thesis is focused in the study and development of a Drive System for a DC Brushless motor. This work was conducted in the Laboratory of Electromechanical Energy Conversion, at the department of Electrical and Computer Engineering, in the University of Patras, Greece. DC Brushless motors, have been used in the last years they are used in a number of applications. They combine all the benefits of a DC motor, such as their operation simplicity and their linear characteristics, avoiding the brushes and the necessary excitation of DC motors, making them a suitable choice for low and medium power applications. The main purpose of this project is the Study and Construction of a Three-Phase Voltage Source Inverter for the control of the performance of a DC Brushless Motor by the implementation of a Scalar control. This thesis began with the simulation of the motor, since it is necessary for the understanding of its dynamic behavior. Then an analysis on the design and construction of the required circuit boards is done. Finally the used microcontroller (dsPIC family) was studied thoroughly, before writing the necessary code(C & assembly) for open and closed loop control. Finally, measurements were taken for the open loop control system. Conclusions were made as far as the behavior of the motor and ways to optimize the control were discussed.

Les travaux de recherche présentés dans ce mémoire, portent sur la conception et l'étude de MOSFETs de puissance faible tension pour des applications automobiles micro-hybrides de type alterno-démarreur. Pour certaines de ces applications, en plus des modes de fonctionnement standards passant et bloqué, les composants développés doivent être capables de fonctionner en mode d'avalanche à fort courant et à des températures élevées. Pour reproduire en laboratoire ces conditions de fonctionnement, les MOSFETs sont soumis à un test UIS répétitif spécifique. Afin d'évaluer la température du silicium pendant ce test, plusieurs méthodes de mesure de température ont été développées et comparées. En parallèle, un suivi des paramètres électriques standards (BVDSS, IDSS, RDSon&) tout au long du test est effectué, dans le but de déterminer l'impact de l'avalanche répétitive sur le transistor. Seule la RDSon des MOSFETs semble évoluer avec le nombre d'impulsions d'avalanche. Ce phénomène est expliqué par la méthode de mesure de RDSon et par la variation de la résistance du métal source pendant le cyclage. En effet, différentes observations ont permis de constater un vieillissement de la métallisation de source du composant, accompagné d'une modification de sa résistivité. Divers types de métaux et de techniques d'assemblage ont alors été expérimentés pour tenter de limiter cet effet. Aussi des structures de test ont été conçues pour étudier l'évolution du métal et pour pouvoir comparer rapidement le comportement de différentes métallisations.