Ce mémoire de thèse présente deux nouvelles approches pour l’analyse et la commande des systèmes non-linéaires complexes, comme les systèmes dynamiques à commutation de la classe des convertisseurs d’énergie électrique. Ces systèmes ont plusieurs modes de fonctionnement et ont un point de fonctionnement désiré qui, en général, n’est le point d’équilibre d’aucun des modes. Dans cette classe de systèmes, la commutation d’un mode de fonctionnement à un autre est commandée selon une loi qui doit être synthétisée. Par conséquent, la synthèse de commande implique l’étude des conditions qui permettent à un cycle limite stable de s’établir au voisinage du point de fonctionnement désiré, puis de la trajectoire de commande qui permet de l’atteindre en respectant les contraintes physiques de comportement (courant maximum supporté par les composants,. . .) ou les contraintes de temps (durée minimum entre deux commutations,. . .). Le cycle limite sera qualifié d’hybride car il est composé de plusieurs dynamiques(deux dans ces travaux).La première méthode développée s’appuie sur les propriétés géométriques des champs de vecteurs et est une extension d’une partie des travaux de thèse de Manon au LAGEP. Une condition nécessaire et suffisante d’existence et de stabilité d’un cycle limite hybride composé d’une séquence de deux modes de fonctionnement dans IR2 est présentée. Ce cycle définit la région finale à atteindre par le système depuis son état initial, par une trajectoire déterminée de manière optimale selon un critère donné (durée totale, énergie dépensée, . . .). La méthode proposée est appliquée aux convertisseurs d’énergie Buck et Buck-Boost alimentant une charge résistive. Une extension à IRn a été proposée et démontrée. Elle est illustrée sur un système non-linéaire dans IR3.La deuxième méthode est développée dans IR2 et basée sur la théorie de Lyapunov, bien connue en automatique pour étudier la stabilité des systèmes non-linéaires et concevoir des commandes stabilisantes.Il s’agit de déterminer par une approche géométrique, une fonction de Lyapunov quadratique commune aux deux modes de fonctionnement du système, qui permette d’obtenir un cycle limite hybride stable le plus proche possible du point de fonctionnement désiré et une commande stabilisante directe des interrupteurs / This PhD-thesis presents two new approaches for the analysis and control of complex nonlinearsystems, such as switching dynamic systems of the class of power converters. These systems have severalmodes of operation and a desired operating point, which, in general, is not the equilibrium point of anymode. In this class of systems, switching from one mode to another is controlled by a switching law tobe designed. Therefore, the synthesis of a control law involves the study of the conditions that allow astable limit cycle to settle near the desired operating point, and of the control trajectory to reach thislimit cycle and stabilize on it, meeting the constraints dues to the physical behavior (maximum currentsupported by the components, . . .) or time constraints (minimum duration between two switchings, . . .).The limit cycle is called hybrid because it is composed of several dynamics (two in this work).The first method is based on the geometric properties of vector fields and is an extension of part ofthe PhD-thesis of Manon at LAGEP. A necessary and sufficient condition of existence and stability of ahybrid limit cycle consisting of a sequence of two operating modes, is presented in IR2. This limit cycledefines the final region to be reached by the system from its initial state, along a trajectory determinedoptimally according to a given criterion (total duration, energy expended, . . .). This method is applied tothe Buck and Buck-Boost power converters with a resistive load. An extension to IRn has been proposedand demonstrated. It is illustrated on a nonlinear system in IR3.The second method is developed in IR2, based on the Lyapunov theory, well known in automatic controlfor studying the stability of nonlinear systems and designing stabilizing control methods. The objective isto design, with a geometric approach, a quadratic Lyapunov function common to both modes of operation,which defines a stable hybrid limit cycle closest to the desired operating point and a direct stabilizingcontrol of the switches.

The increasing demand for high performance and miniature high frequency electronics has motivated the development of Micro-electro Mechanical Systems (MEMS) resonators, some of which have already become a commercial success for the making of filters, duplexers and oscillators used in radio frequency (RF) front-end systems for portable electronic devices. These MEMS components not only enable size, power and cost reduction with respect to their existing counterparts, but also open exciting opportunities for implementing new functionalities when used in large arrays. Almost all MEMS resonators require interfacing with one or more Complementary Metal Oxide Semiconductor (CMOS) integrated circuit components or modules in processing raw signals from individual MEMS devices. Hence, these devices should be integrated with CMOS circuits in an efficient and robust way in order to facilitate their deployment in large arrays with minimal parasitics, delay and power losses due to signal routing and CMOS-MEMS interconnects. Among the MEMS resonators developed to date, Aluminum Nitride (AlN) MEMS Contour-Mode Resonators (CMRs) offer high electro-mechanical coupling coefficient (𝑘𝑡2) and quality factor (Q), and a center frequency (f0) that can be set lithographically by varying the device in-plane dimensions. Also, AlN MEMS CMRs can be fabricated using state-of-the-art CMOS processes and micromachining techniques. These properties allow the synthesis of multi-frequency band-pass filters (BPFs) on a single chip with a low insertion loss and the capability of direct matching to 50 Ω systems. All these advantages, along with a sufficiently mature fabrication process, make AlN CMRs one of the ideal candidates for pursuing their integration with CMOS technology and implement high performance filters with programming capability. In this work we develop for the first time a three-dimensional (3D) heterogeneously integrated AlN MEMS-CMOS platform that enables the realization of such systems as self- healing filters for RF front-ends and programmable filter arrays for cognitive radios. We collaborated with the A*STAR, Institute of Microelectronics (IME), Singapore in the development of AlN MEMS platform on an 8" silicon (Si) wafer; on the other hand, CMOS chips were fabricated in 65 nm International Business Machines Corporation (IBM) and 28 nm Samsung processes. Solder bumps were placed on CMOS chips by Tag and Label Manufacturers Institute (TLMI) under the supervision of Metal Oxide Semiconductor Implementation Service (MOSIS). We demonstrated 3D integrated chip stacks with primary RF signal routing on MEMS and on CMOS for self-healing filters, and showcased the other system via wire-bonding to off-the-shelf CMOS components on a printed circuit board (PCB) because of the inability to continue to have access to the CMOS wafers and bumping processes over the last two years of the project.

High frequency link power converters for DC – 3Φ AC applications are investigated. Low cost, reduced size, galvanic isolation and efficient large boosting of voltage level are the key motivations behind the selection of such topologies. This thesis proposes high frequency link 3Φ inverters for three wire and four wire systems. The proposed topologies have the simplest power circuit configuration and commutation requirements among all high frequency link topologies reported in the literature. A full load efficiency greater than 90% is achieved with a passive snubber. The effect of various circuit non-idealities are common and important for desirable performances of these topologies. A few such issues are highlighted. Firstly, the special commutation requirement of the power circuit causes a non-linear distortion in the output voltages and thus makes the gain of the power converter time varying. A simple compensation technique is adopted to mitigate the problem. Secondly, the high frequency transformer should operate with only switching frequency component. However, in the practical situations a significant amount of low frequency component gets injected into the transformer and results in peaky transformer magnetizing current unless it is over designed. A suitable measure is incorporated in the proposed topologies to achieve a magnetic protection. The power circuit topology is used as stand-by AC power supply. These are of interest for Uninterruptible Power Supply (UPS) and Micro-grid applications. One of the main objectives of such supplies is to provide a high quality and highly reliable power to the connected loads. A voltage regulation loop based on proportional + multiresonant controller is proposed to achieve excellent quality of the output voltage with unbalanced and nonlinear loadings. The factors influencing regulation and stability of the voltage waveform are identified and necessary modifications are carried out to improve the performance. The potential of this voltage regulation loop along with P/Q droop technique and a simple resistive virtual output impedance loop is exploited to achieve decentralized paralleling of inverters. A trade off between the output voltage power quality and the sharing accuracy is examined. The total harmonic distortion and degree of unbalance in the output voltage waveform are experimentally measured well below the specified limit for stand alone AC supplies with an excellent sharing accuracy. Some of the grid interactive modes are addressed for the completeness of the work. A shunt compensator system and a double conversion system based on the same high frequency link converter are experimentally evaluated. These systems can find their application in UPS systems. A few important observations on the power circuit performances are indicated.

Renewable energy sources normally require power converters to convert their energy into standardized regulated ac output. The motivation for this thesis is to design and control power converters for renewable energy systems to ensure very good power quality, efficiency and reliability. The renewable energy sources considered are low voltage dc sources such as photovoltaic (PV) modules. Two transformer-isolated power circuit topologies with input voltage of less than 50V are designed and developed for low and medium power applications. Various design and control issues of these converters are identified and new solutions are proposed. For low power rating of a few hundred watts, a line-frequency transformer interfaced inverter is developed. In the grid connected operation, it is observed that this topology injects considerable lower order odd and even harmonics in the grid current. The reasons for this are identified. A new current control method using adaptive harmonic compensation technique and a proportional-resonant-integral (PRI) controller is proposed. The proposed current controller is designed to ensure that the grid current harmonics are within the limits set by the IEEE 1547-2003 standard. Phase-locked loops (PLLs) are used for grid synchronization of power converters in grid-tied operation and for closed-loop control reference generation. Analysis and design of synchronous reference frame PLL (SRF-PLL) and second-order generalized integrator (SOGI) based PLLs considering unit vector distortion under the possible non-ideal grid conditions of harmonics, unbalance, dc offsets and frequency deviations are proposed and validated. Both SRF-PLL and SOGI-PLL are low-complexity PLLs. The proposed designs achieve fastest settling time for these PLLs for a given worst-case input condition. The harmonic distortion and dc offsets in the resulting unit vectors are limited to be well within the limits set by the IEEE 1547-2003 standard. The proposed designs can be used to achieve very good performance using conventional low-complexity PLLs without the requirement of advanced PLLs which can be computationally intensive. A high-frequency (HF) transformer interfaced ac link inverter with a lossless snubber is developed medium power level in the order of few kilowatts. The HF transformer makes the topology compact and economical compared to an equally rated line frequency transformer. A new synchronized modulation method is proposed to suppress the possible over-voltages due to current commutation in the leakage inductance of the HF transformer. The effect of circuit non-ideality of turn-on delay time is analyzed. The proposed modulation mitigates the problem of spurious turn-on that can occur due to the turn-on delay time. The HF inverter, rectifier and snubber devices have soft switching with this modulation. A new reliable start-up method is proposed for this inverter topology without any additional start- up circuitry. This solves the problems of over-voltages and inrush currents during start-up. The overall research work reported in the thesis shows that it is possible to have compact, reliable and high performance power converters for renewable energy conversion systems. It is also shown that high control performance and power quality can be achieved using the proposed control techniques of low implementation complexity.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-07-11T12:39:13Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação Mestrado M276 - Gilberto.pdf: 3559945 bytes, checksum: e0e92cec09c72c5a7b8b98260c3b9a8e (MD5) / Made available in DSpace on 2017-07-11T12:39:13Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertação Mestrado M276 - Gilberto.pdf: 3559945 bytes, checksum: e0e92cec09c72c5a7b8b98260c3b9a8e (MD5) Previous issue date: 2016-03-22 / Este trabalho apresenta um estudo comparativo de conversores monofásicos aplicados a sistemas fotovoltaicos sem transformador. Topologias de inversores sem transformador têm menores custos, tamanho e peso. Contudo, a não utilização do transformador pode ser responsável por consideráveis valores de correntes de fuga. A associação em série de vários módulos fotovoltaicos se faz necessária para alcançar o nível de tensão desejado no barramento c.c.. Com o intuito de reduzir o número de módulos fotovoltaicos em série, topologias com característica de elevação de tensão (boost) podem ser utilizadas. Portanto, topologias que possuem estas características e que possam apresentar baixos valores de correntes de fuga devem ser escolhidas para o estudo. As topologias presentes neste trabalho são: o conversor de dois estágios, o inversor fonte Z monofásico com diodo adicional, e o inversor fonte Z de três estados. / This work presents a comparative study of single-phase converters applied to transformerless photovoltaic systems. Topologies of transformerless inverters have lower costs, size and weight. However, not using it may cause considerable amounts of leakage currents. The association in series of several PV modules is needed to achieve the voltage level desired in d.c. bus. In order to reduce the number of photovoltaic modules in series, topologies with voltage boost characteristic can be used. Therefore, topologies that have voltage boost characteristic and can have low leakage current values are chosen for the study. Topologies present in this work are: the two stages single-phase converter, the single-phase Z-source inverter with additional diode, and the single-phase three switch three state Z-source inverter.

Le régulateur PID (Proportionnel-Intégral-Dérivée) est la commande par retour d'état la plus connue. Elle permet d'aborder un bon nombre de problèmes de commande, particulièrement pour des systèmes faiblement non linéaire et dont la performance requise est relativement modeste. En plus, en raison de sa simplicité, la commande PID est largement utilisée en l'industrie. Étant donnés que les méthodes de réglage de la commande PID sont basées sur la linéarisation, la synthèse d'un contrôleur autour d'un point d'équilibre est relativement simple, néanmoins, la performance sera faible dans des modes de fonctionnement loin du point d'équilibre. Pour surmonter ce désavantage, une pratique courante consiste en adapter les gains du PID, procédure connue sous le nom de séquencement de gain (ou gain-scheduling en anglais). Il y a plusieurs désavantages à cette procédure, comme la commutation des gains de la commande et la définition -non triviale- des régions de l'espace d'état dans lesquelles cette commutation aura lieu. Ces deux problèmes se compliquent quand la dynamique est fortement non linéaire. Dans d'autres méthodes, la synthèse de la commande utilise des schémas empiriques, ce qui ne permet pas l'analyse de la stabilité globale du processus. Dans ce contexte, ce travail de thèse a pour objectif de synthétiser des contrôleurs PI, basés sur la passivité, de telle sorte que la stabilité globale du système en boucle fermé soit garantie. L'un des avantages à utiliser la passivité est son attrait intuitif, qui exploite les propriétés physique des systèmes. L'idée centrale dans un système passive est que l'écoulement d'énergie entrante au système provenant de l'extérieur n'est pas inférieur à l'incrément de son énergie de stockage. Par conséquence, ces systèmes ne peuvent pas stocker plus d'énergie que celle fournie, dont la différence correspond à l'énergie dissipée. En introduisant le concept d'énergie, cette méthodologie nous permet de formuler le problème de commande en celui de trouver un système dynamique dont la fonction de stockage d'énergie prend la forme désirée. En incorporant le concept d'énergie cette méthode devient accessible à la communauté de praticiens et permets de fournir des interprétations physique de l'action de commande. Dans cette thèse, une méthodologie constructive de commande PI basée sur la passivité est présentée et motivée par des applications à des systèmes physiques. / One of the best known forms of feeding back a system is through a three-term control law called PID (Proportional-Integral-Derivative) controller. PID controllers are sufficient for many control problems, particularly when process dynamics are not highly nonlinear and the performance requirements are modest. Besides, because of its simple structure, the PID controller is the most adopted control scheme by industry and practitioners, beeing the PI the form mostly employed. Since the PI tuning methods are based on the linearization, commissioning a PI to operate around a single operating point is relatively easy, however, the performance will be below par in wide operating regimes. To overcome this drawback the current practice is to re-tune the gains of the PI controllers based on a linear model of the plant evaluated at various operating points, a procedure known as gain-scheduling. There are several disadvantages of gain-scheduling including the need to switch (or interpolate) the controller gains and the non-trivial definition of the regions in the plants state space where the switching takes place - both problems are exacerbated if the dynamics of the plant is highly nonlinear. In other common scenarios, a little information about the process dynamics or only a "good" linear approximation is taken into account when designing the control design. This impedes to analyse the global stability of the system. In this context, the current thesis work is aimed at the designing of PI controllers, based on the passivity theory, such that the stability of the closed-loop system is guarantied. One of the main advantages of passivity concepts is that they offer a physical and intuitive appeal. The primary idea in passive systems is that the power flowing into the system is not less that the increase of storage. Thus, they cannot store more energy than is supplied to it from the outside, with the difference being the dissipated energy. Thus, introducing the concept of energy, this methodology allows to recast the control problem as finding a dynamical system such that system energy function takes the desired form. Also, with this formulation, the communication between practitioners and control theorists is facilitated, incorporating prior knowledge of the system and providing physical interpretations of the control action. In this thesis, a constructive methodology for deriving PI passivity-based controllers is presented and motivated by the application to physical systems.

Modular Multilevel Converters (MMCs), over recent years, have gained popularity in high-voltage(HV) and medium-voltage (MV) applications due to their high reliability. Also, with the rapid growth of solar photovoltaics (PV) and energy storage systems, there is a high demand for efficient and reliable power converter solutions. Therefore, due to the seen merits behind MMCs, this thesis assesses their performance for low-voltage (LV) applications. This is accomplished by comparing basic MMC solutions with an equivalent flying capacitors based solution. Such comparison is based on the evaluation of the passive elements requirements, semi-conductor losses, area, voltage, and current stresses, and common-mode voltage. It is worth mentioning that the evaluation is based on utilizing LV MOSFETs. Furthermore, the thesis introduces a modulation scheme for the full-bridge submodule MMC, thus further exploring the different operating regions of the full-bridge based MMC.

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