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Voice commanded systems (VCS) have been proved to be vulnerable to signal in- jections mimicking voice commands and explored security flaws in market avail- able products for the time of each respective study. Signal injection caused with the help of amplitude modulated ultrasonic waves (being known as DolphinAt- tacks - DA) were proved to work on several such devices in 2017. In 2019, another study were also successful in achieving signal injections using modulated laser also known as LightCommands (LC). This thesis has investigated the occurring circumstances which enables such injections. Simulations and laboratory trials have shown a thermoacoustic origin enabling LC to be injected and the response differs with respect to microphones physical size. DA utilizes the non-linearity of microphones and more linear microphones have indeed been shown to withstand DAs better and physical parameters have been shown to indicate how DA may be optimized for successful injections. The results have been used to provide ideas on how a VCS system can be designed to be more resilient. / Röststyrda System har visat sig vara sårbara mot signalinjektioner som härmar röstkommandon och utnyttjar kryphål hos produkter som fanns på marknaden i samtid när studierna som först tog upp kryphålen publicerades. Signalinjek- toner inducerade med hjälp av amplitudmodulerat ultraljud (känt som Dolphi- nAttacks - DA) bevisades fungera på flertalet enheter år 2017. 2019 visade en annan studie framgång med signalinjektion genom modulerad laser, även känt som LightCommands (LC). Detta examensarbete har utrett de bakomliggande faktorer som möjliggör sådana injektioner. Simuleringar och laboratorieexperi- ment har visat att termoakustiska effekter möjliggör LC med resultat som beror på mikrofoners fysiska storlek. DA nyttjar ickelinjäritet hos mikrofoner och linjä- rare mikrofoner har visat sig stå emot DA bättre och det har visat sig att DA kan optimeras för bättre lyckade injektioner. Resultaten har används för att bidra till idéer och resonemang från föregående studier på hur lösningar mot LC och DA skulle kunna implementeras och göra mikrofoner och dess tillhörande system tåligare mot sådana angrepp.

The objective of the dissertation is to develop simplified analytical models for typical linear-motion and rotary-motion energy-conversion systems under active DC excitation without tedious numerical-simulation effort, and provide practical implementation of the models in optimal-design and thermal-protection aspects. The model of a vacuum automatic circuit recloser (a typical linear-motion system under DC excitation) is first developed in the form of a non-linear discontinuous eighth-order dynamic system. The model is then used to simulate the transient mechanical and electromagnetic performance during the opening and closing movements of the recloser. Such a model is not found in the literature. Although the model is based on certain simplifying assumptions, the result is validated by high-speed-camera measurements. In addition, the impact of key design variables is explored, based on which an improved recloser design is proposed, and helps to optimize capital and production costs without degrading performance. Further analytical investigation is carried out in modeling an inverter-fed induction motor (IM) (a typical rotary-motion system) with active DC injection. The IM is closed-loop controlled via two popular motor-control algorithms, namely, the direct-torque-control (DTC) algorithm and field-oriented-control (FOC) algorithm. Quantitative relationships between the changes of various machine variables during the active DC excitation are provided in the theoretical analysis. The developed DC-injection model is further simplified for practical implementation. The developed IM model under DC injection results in practical ways to excite a proper amount of DC current directly or indirectly into IM stator windings via different closed-loop motor-control algorithms. In a DTC motor-drive system, the modeling work makes it possible to excite the DC current indirectly inside the motor by superimposing a stator-flux-linkage-bias command in the flux-control loop or a torque-ripple command in the torque-control loop. The proposed flux-linkage-injection and torque-injection methods are the first novel efforts to implement the DC-signal-injection method in a DTC motor-drive system. In addition, the analysis carried out in a standard FOC drive system brings about an improved DC-current-injection approach: the torque ripple in this method is significantly mitigated compared to all existing DC-injection methods in FOC systems. The proposed DC-injection methods, either in a DTC or an FOC system, lead to a simple, low-cost, accurate, and non-invasive thermal-monitoring scheme for closed-loop-controlled IMs, where the stator temperature is indirectly estimated from stator resistance. Furthermore, considering inverter non-idealities, there is a challenge for a typical inverter drive to accurately estimate the DC component of motor terminal voltages. The existing methods are extended to provide a complete study of the real-time signal-processing technique for both DTC and FOC algorithms, and are finally implemented in a custom-built programmable motor-drive system. The experimental results demonstrate that the proposed technique gives accurate and robust stator-temperature estimation, regardless of the operating conditions and cooling modes. The analytical modeling method for the linear-motion and rotary-motion energy-conversion systems can be further extended to other power devices with similar mechanisms, and implemented in optimal design, control, and thermal-protection areas.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-03-27T15:28:12Z No. of bitstreams: 1 ramonreissiqueiradeoliveira.pdf: 4744081 bytes, checksum: dbce2e20c42a3bc456ad52a2096349ec (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-03-27T17:52:51Z (GMT) No. of bitstreams: 1 ramonreissiqueiradeoliveira.pdf: 4744081 bytes, checksum: dbce2e20c42a3bc456ad52a2096349ec (MD5) / Made available in DSpace on 2018-03-27T17:52:51Z (GMT). No. of bitstreams: 1 ramonreissiqueiradeoliveira.pdf: 4744081 bytes, checksum: dbce2e20c42a3bc456ad52a2096349ec (MD5) Previous issue date: 2017-12-18 / Uma rede com vários geradores distribuídos conectados pode melhorar a eficiência energética e reduzir o impacto negativo na rede elétrica. Um problema que surge é quando o fornecimento de energia principal é desconectado do sistema, diz-se então que ocorreu um ilhamento. Essa situação é indesejada, pois pode provocar problemas em termos de qualidade de energia, segurança, tensão e estabilidade de frequência. Esse trabalho tem por finalidade identificar o ilhamento pela variação da impedância do sistema, utilizando um método proposto que utiliza uma técnica de estimação de impedância através da injeção de um pequeno sinal na tensão de saída do gerador distribuído. Os testes realizados mostraram que quanto maior for a contribuição do inversor na potência fornecida para a carga, melhores são os valores estimados de impedância e na presença de dois inversores, os sinais injetados por cada um deles devem estar em frequências harmônicas o mais distante possível, para melhores resultados na estimação da impedância. Além disso, quando o fluxo de potência da rede para a carga é próximo de zero, o método foi capaz de identificar o ilhamento mesmo cosem atuação dos relés de tensão e frequência. O ilhamento é possível de ser identificado em aproximadamente 0,5 s em todos os casos testados, estando dessa forma dentro do tempo máximo estabelecido nas normas. / A grid with multiple distributed generators can improve energy efficiency and reduce the negative impact on itself. One problem that occurs is when the main power supply is disconnected from the system, this is called islanding. This is undesirable because it can cause problems in terms of power quality, safety, voltage and frequency stability. This work aims to identify the islanding by the system impedance variation, using a proposed method that uses an impedance estimation technique, injecting a small signal into the output voltage of the distributed generator. The tests performed showed as higher the contribution of the inverter to the power supplied to the load as better the estimated impedance values. In the presence of two inverters, the signals injected by each of them must be in harmonic frequencies, for better impedance estimation results. In addition, when the utility energy flow to the load is close to zero, the method was able to identify the same island as the voltage and frequency relays. The island can be identified in approximately 0.5 s in all cases tested, thus being within the maximum time limit set in the standards.

Le travail de recherche présenté dans ce mémoire concerne le développement de capteurs logiciels de position pour la commande de la machine synchrone à aimants permanents. La commande vectorielle de la MSAP nécessite une connaissance précise de la position rotorique. Traditionnellement, cette position est obtenue à partir de l’utilisation d’un capteur mécanique.Depuis des années, l’attention de la communauté scientifique s’est portée sur la limitation du nombre de capteurs vu que leur présence, non seulement augmente le coût et la complexité matérielle totale, mais aussi réduit sa fiabilité avec une sensibilité additionnelle aux perturbations extérieures. Dans une première partie, nous présentons plusieurs types de capteurs logiciels deposition pour la MSAP. En fonction du régime de fonctionnement de la machine, nous proposons le capteur, selon nous, le mieux adapté pour une application automobile. Ce capteur est basé sur le couplage intelligent entre un observateur et un capteur logiciel basé sur la technique d’injection de signaux. Dans une deuxième partie, nous proposons une méthode simple et rapidepermettant l’estimation de la résistance et des inductances statoriques à l’arrêt. La méthode proposée, basée sur la technique d’injection de signaux de haute fréquence, exploite la mise en oeuvre des filtres à variable d’état afin d’obtenir un modèle linéaire par rapport aux paramètres. La combinaison de l’identification à l’arrêt et du capteur logiciel permet une bonne estimationde la position de la MSAP sur une large plage de vitesse y compris les basses vitesses et à l’arrêt. Nous abordons également certains aspects de commande de robustesse vis-à-vis de l’ensemble des paramètres incertains de la machine, mais ce de manière plus prospective. / This thesis focuses on the development of soft sensors for position control of the permanent magnet synchronous machine. Vector control of PMSM requires accurate knowledge of the rotor position. Traditionally, this position can be obtained from a mechanical sensor. Many years ago, the attention of the scientific community has focused on reducing the number of sensorsbecause their presence not only increases the cost and the total hardware complexity, but also reduces its reliability with an additional sensitivity to external disturbances. As a first step, we present several known types of soft sensors for PMSM. We present the complete design of a soft sensor for speed measurement of permanent magnet synchronous motor. The rotor speedand position can be estimated in a wide speed range even at low speed and standstill. We introduce two soft sensors operating in two different ranges of speed. Secondly, a simple method based on high frequency signal injection and exploiting the implementation of state variable filters to obtain a linear model with respect to the parameters is presented. Thus, a simplifiedprocedure of identification based on a least squares algorithm can be used. In an automotive application, the PMSM parameters can change due to temperature variation and aging of the material. Therefore, the coupling of the hybrid soft sensor and the simplified pocedure of identification provides a good estimate of the PMSM position over a wide speed range including standstill. We also consider a new approach to the robust control of the PMSM, but just as a newtrack for further investigations.

Sans capteur,estimation de la position/vitesse,injection d'un signal HF,apprentissage,MSAPI,VE, / In EV traction applications, most of the mentioned criteria are inescapable, in particularthose related with cost (real-time implementation, additional hardware, etc.), those relatedwith functional requirements (torque ripple, motor efficiency, etc.) not to mention thatsensorless operation must cover the complete speed range.

Grace à leur forte densité de puissance et leur facilité de commande, les machines synchrones à aimants permanents (MSAP) sont fréquemment utilisées pour motoriser les actionneurs aéronautiques. Afin de pouvoir assurer le pilotage de ces moteurs, une information précise sur la position du rotor est nécessaire. Des capteurs de position sont utilisés pour mesurer la position et calculer la vitesse du rotor. Les inconvénients inhérents à l'utilisation de ces capteurs sont la diminution de la fiabilité du système et l'augmentation du poids, du volume, et du coût total du celui-ci. Dans ce travail, nous présentons une commande ne nécessitant pas le capteur de position à l'aide d'algorithmes d'estimation des variables mécaniques uniquement à partir de la mesure des courants statoriques. Après avoir abordé les méthodes de commande sans capteur adaptées aux hautes vitesses et basées sur l'estimation de la force électromotrice, nous établissons un état de l'art des méthodes de contrôle à basses vitesses basées sur la saillance du rotor. Une nouvelle méthode de commande sans capteur en basses vitesses et à l'arrêt, indépendante des paramètres du moteur et très simple à implanter est ensuite proposée et validée en simulation (sur un modèle de MSAP prenant en compte les effets de saturation) puis sur banc d'essais. Une étude analytique sur la convergence de l'algorithme et sa robustesse est également réalisée. Enfin, un processus d'initialisation ainsi qu'une méthode de transition sans à-coups entre les méthodes basses et hautes vitesses sont proposées et validées par simulation et expérimentation / For their high power density and ease of control, permanent magnet synchronous motors (PMSM) are widely used in more electric aircraft. In order to control PMSMs, precise information on the rotor position is required. This information is provided by position sensors which have inherent drawbacks despite their good precision: these sensors decrease reliability and increase weight, volume, and cost of the whole system. In this thesis, we present a mechanical sensorless control method by estimating the rotor speed and position only from the phase currents measurements. Sensorless control methods suitable for high speeds and based on back-EMF estimation are first discussed. Then, a state of the art in sensorless methods for low speeds operations is presented. A new sensorless control, independent from the motor parameters, is presented for operating at low speeds and standstill. Both simulations (on a PMSM model taking into account the saturation phenomenon) and experimental results show the effectiveness of this model-independent method. A convergence analysis and a robustness study of the proposed algorithm are also made. Finally, an initialization process and a method for smooth transition between low and high speeds methods are proposed and validated on an experimental test-bench

In this thesis, shaft transducerless vector control of Interior Permanent Magnet (IPM) motor with speed and position estimation using saliency based high frequency signal injection and fundamental model based flux observer methods will be investigated. The magnetic saliency characteristic of a 2.2-kW IPM motor will be experimentally extracted by means of high frequency signal injection. High frequency signal injection method will be used to estimate the speed and position at zero and low speed based on the magnetic saliency of the IPM motor. At high speed, fundamental model based flux observer method will be utilized for speed and position estimation. Seamless transition between the two estimation methods will be provided. Using the estimated speed and position information, the motor will be closed loop vector controlled and the drive motion performance over wide speed and load range will be investigated. The IPM motor drive and the estimation/control algorithms will be modeled and their performance will be demonstrated by detailed computer simulations. A three-phase voltage source inverter and a motor test bench will be built, and the estimation/control algorithms will be implemented on a DSP based motor control platform. The IPM motor drive system will be tested in the laboratory and the theory and simulation results will be verified by the experiments.

This thesis presents two transient models for a prototype integrated charger for use in a plug-in hybrid-electrical vehicle application. The models can be useful in order to develop control algorithms for the system or to recommend improvements to the machine design. A flux map based method, obtaining input data from simulations using the finite element method (FEM) is used to model the grid synchronization process. The grid side voltage can then be predicted by incorporating spatial flux linkage harmonics. The model is implemented in Matlab/Simulink and compared to stand alone FEM simulations with good agreement. The charging process is modeled using an inductance based model also requiring FEM simulations as input data. Since the flux linkages in the grid and inverter side windings are dependent on each other, the presented transient model is linearized around a specific operating point. This model is also implemented in a Matlab/Simulink environment. Sensorless control of a PMSynRel drive is also studied in this thesis. Focus is put on operating limits due to magnetic saturation when operating at low speeds. The rotating and pulsating voltage vector injection methods for sensorless control are studied in detail. A technique to map the feasible sensorless control region is proposed which utilizes the resulting position error signal rather than data of differential inductances. This technique is implemented experimentally and compared to corresponding FEM simulations with good agreement. The impact of spatial inductance harmonics on the quality of the position estimates is also studied. A method to predict the maximum position estimation error due to the inductance harmonics is proposed based on simplified analytical models. A technique is presented and experimentally verified which can compensate for this effect by injecting a modified rotating voltage carrier. Lastly, the impact of saturation in the rotor structure on the initial magnet polarity detection is investigated. The experimental results, in good agreement with the corresponding FEM simulations, indicate that the impact of saturation in the magnet bridges of rotor is the dominant phenomenon at lower peak current magnitudes. / QC 20110928

Les avionneurs expriment le besoin de développement de l’avion plus « électrique ». Cela se traduit par des besoins nouveaux en matière de systèmes de motorisation électrique, en termes de puissance à fournir et de partage de ressources matérielles en vue de minimiser la masse embarquée et les coûts. Parmi les études en cours sur l’évolution des machines tournantes, un intérêt particulier porte sur le développement des alterno-démarreurs de type machines synchrones sans balais et à plusieurs étages (BSSG). Celles-ci sont susceptibles de fournir un fort couple lors des phases de démarrage des réacteurs auxquelles elles sont associées. Pour ce faire, la connaissance, à tout moment, de la position du rotor est essentielle. Cependant, l'ajout d’un capteur dédié impacte la conception de la machine, rajoutant du volume, du câblage et augmentant le coût. La réalisation d'une commande dite « sensorless » permettrait de s'affranchir de l'utilisation d'un tel capteur et de simplifier le design des alterno-démarreurs.A partir d'une modélisation fine de la machine, cette thèse étudie les conditions dans lesquelles une telle commande est réalisable et analyse plusieurs techniques permettant d'y parvenir. Une nouvelle méthode d'estimation de la position du rotor, spécifique aux BSSG est proposée, puis illustrée avec des résultats expérimentaux. Cette technique est basée sur le traitement des composantes harmoniques existantes naturellement au stator de la machine et permet l'estimation de la position à l'arrêt et à très basse vitesse. Afin d'étendre l'estimation sur toute la plage de vitesse, une étude d'estimation de position par un observateur d'état à base du modèle complet de la machine en considérant les harmonique injectés (ou existantes) dans les courants du stator est proposée. Cet observateur peut s’appliquer à la machine synchrone à trois étages mais aussi à toute machine synchrone. Dans cette étude, son fonctionnement est illustré sur une machine synchrone à aimants permanents. / The aircraft manufacturers express the need to develop a more "electric" aircraft. This brings forward new requirements for the electric drive systems in terms of increasing the available on-board power and resource sharing in order to optimize the overall mass and cost. Among the ongoing studies on the evolution of motor drives, a particular interest is given to the development of multi-level brushless synchronous starter/generators (BSSG). These drives are likely to provide the high torque required to start-up the reactors to which they are associated. For this purpose, the knowledge, at any time, of the rotor position is essential. However, adding a dedicated sensor impacts on the design of the machine, increasing volume, cabling needs and cost. For this purpose, investigating on “sensorless” control laws will permit to avoid using such a sensor and to simplify the design of the Starter/Generators.Using a fine modelling of the machine, this work studies the conditions of feasibility for sensorless control and analyzes several techniques for this purpose. A new method of estimation of the shaft-position, particular to the BSSG architecture is proposed and then illustrated with experimental results. This technique is based on the processing of the existing harmonic components naturally in the stator of the machine and allows the estimation of the position at standstill and the very low speed. To extend the estimation to the whole speed range, a study of position estimation using a state observer using the complete model of the machine considering the knowledge of the existing (or injected) harmonic components in the stator currents is proposed. This observer can be applied to the brushless synchronous starter/generator but also on generic synchronous machines. In this study, its performance is illustrated on a permanent magnet synchronous machine.