The battery is a component with significant impact on both the cost and environmental footprint of a full electric vehicle (EV). Consequently, there is a strong motivation to maximize its degree of utilization. Usage limits are enforced by the battery management system (BMS) to ensure safe operation and limit battery degradation. The limits tend to be conservative to account for uncertainty in battery state estimation as well as changes in the battery's characteristics due to aging. To improve the utilization degree, aging sensitive battery control is necessary. This refers to control that a) adjusts during the battery's life based on its state and b) balances the trade-off between utilization and degradation according to requirements from the specific application.  In state-of-the-art battery installations, only three signals are measured; current, voltage and temperature. However, the battery's behaviour is governed by other states that must be estimated such as its state-of-charge (SOC) or local concentrations and potentials. The BMS therefore relies on models to estimate states and to perform control actions. In order to realize points a) and b), the models that are used for state estimation and control must be updated onboard. An updated model can also serve the purpose of diagnosing the battery, since it reflects the changing properties of an aging battery. This thesis investigates identification of physics-based and empirical battery models from operational EV data. The work is divided into three main studies. 1) A global sensitivity analysis was performed on the parameters of a high-order physics-based model. Measured current profiles from real EV:s were used as input and the parameters' impact on both modelled cell voltage and other internal states was assessed. The study revealed that in order to excite all model parameters, an input with high current rates, large SOC span and longer charge or discharge periods was required. This was only present in the data set from an electric truck with few battery packs. Data sets from vehicles with more packs (electric bus) and limited SOC operating window (plug-in hybrid truck) excited fewer model parameters. 2) Empirical linear-parameter-varying (LPV) dynamic models were identified on driving data. Model parameters were formulated as functions of the measured temperature, current magnitude and estimated open circuit voltage (OCV). To handle the time-scale differences in battery voltage response, continuous-time system identification was employed. We concluded that the proposed models had superior predictive abilities compared to discrete and time-invariant counterparts.  3) Instead of using driving data to parametrize models, we also investigated the possibility to design the charging current in order to increase its information content about model parameters. This was formulated as an optimal control problem with charging speed and information content as objectives. To also take battery degradation into account, constraints on polarization was included. The results showed that parameter information can be increased without significant increase in charge time nor aging related stress. / Elekriska fordon utgör en allt större andel av världens fordonsflotta. Batteriet är en komponent med betydande påverkan både på fordonets kostnadoch dess miljö- och klimatpåverkan. Det är därför viktigt att försöka maximera batteriets utnytjandegrad. Användargränser upprätthålls av batterietsstyrsystem, såkallad BMS, för att garantera säker drift samt för att begränsabatteriets åldrande. Användargränserna tenderar att vara konservativa för attta höjd för osäkerhet i tillståndsestimeringen samt batteriets förändrade egenskaper under dess livstid. För att utöka utnyttjandegraden är ålderskänsligstyrning nödvändig. Med detta avses styrning som a) justeras under batterietslivstid och b) balancerar utnyttjande och prestanda på ett sätt som passar enspecifik applikation. Ombord på fordon mäts typiskt tre signaler; ström, spänning och temperatur. Batteriets beteende bestäms dock av andra tillstånd som måste estimeras, såsom dess laddnivåeller lokala koncentrationer och potentialer. BMS:enförlitar sig därför på modeller för att estimera interna tillstånd och utföra styrning. För att uppfylla punkterna a) och b) måste modellerna som användsuppdateras ombord i takt med att batteriet åldras. En uppdaterad modellkan också fungera som ett diagnostiskt verktyg eftersom det speglar batteriets förändrade egenskaper. Den här avhandlingen undersöker identifieringav fysikbaserade och empiriska modeller från kördata. Arbetet delas in i treseparata studier. 1) En global känslighetsanalys utfördes på parametrarna i en fysikbaseradmodell av hög ordning. Som inputsignal användes uppmätt ström från riktigaelfordon i drift. Parametrarnas effekt på både cellspänning och interna batteritillstånd analyserades. Studien visade att alla modellparametrar exciteradesav strömmen från ett helelektriskt fordon. Anledningen var att batteriernaanvändes inom ett brett SOC spann samt att den dragna strömmen var stor.I fordon med snävare SOC span och lägre strömmar var inte alla parametrarkänsliga. 2) Dynamiska parametervarierande modeller formulerades och identifierades från kördata. Den uppmätta temperaturen, samt strömmens storlekoch den estimerade tomgångsspänningen (OCV) användes till parameterberoenden. För att hantera skillnader i tidsskala mellan spänningssvarets olikakomponenter användes systemidentifiering i kontinuerlig tid. Vi kunde draslutsatsen att de föreslagna modellerna var överlägsna motsvarande diskretaoch konstanta modeller. 3) Istället för att använda kördata för att parametrisera modeller undersökte vi också möjligheten att designa laddförloppet för att öka dess informationsinnheåll. Detta formulerades som ett optimeringsproblem med laddtidoch informationsinnehåll i kostnadsfunktionen. För att även ta batteriets åldrande i beaktning, ansattses bivillkor på polariseringsspänningen. / <p>QC 20220516</p>

ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY (EIS) has been widely used to study the electrical properties of biological material due to its non-invasive nature and experimental reliability. However, most of the precision impedance analyzers used in EIS only provide single- or two-channel measurements which are inadequate for larger-scale multiplexed measurements, such as those found in modern microfluidic cell culture experiments. The Biomedical Microsystems Laboratory has developed a 16-channel cell culture platform with integrated electrode arrays for monitoring cell growth and electrical properties (i.e., the so-called “electrical phenotype”). In this paper, a system consisting of a 16-channel solid-state analog multiplexer (MUX)paired with a low-cost, impedance analyzer is developed to replace high-cost physical relay MUX and impedance analyzer systems. System requirements and design constraints for monitoring biological systems are considered and a prototype device was fabricated. Initial testing was performed on a breadboard to verify the feasibility of the design idea. Results identified measurement errors due to parasitic elements in the system. Software compensation successfully corrected for parasitic capacitance in the analog MUX design. The accuracy of the measurement system was evaluated on a developed Printed Circuit Board Assembly (PCBA) by comparing theoretical values to MUX compensated data. Finally, an EIS experiment was carried out with tap water with the PCBA system, and measurement results were analyzed using an equivalent Circuit Model (ECM). These results successfully captured the dynamics of charge transport in the electrical double layer, consistent with a modified-Randlecell ECM.

[pt] O surgimento do fenômeno de estabilidade de tensão na operação dos sistemas elétricos motivou centenas de pesquisadores a desenvolverem métodos que permitam detectar a proximidade à instabilidade de tensão, com eficiência computacional, e tomar medidas acertadas para garantir a operação confiável e segura. Neste trabalho são analisados diferentes métodos que permitem transformar sistemas de grande porte em circuitos simples: o circuito equivalente entre geradores e cargas, baseado no cálculo de correntes de curto-circuito, na técnica de redução de rede pela eliminação de barras intermediárias e no equivalente de Thévenin. É analisada a utilização destes equivalentes na avaliação das condições de estabilidade de tensão com sistemas-testes de 3 e 4 barras. Através de diferentes testes verificou-se que o circuito equivalente entre geradores e cargas e a técnica de redução de rede não podem ser usados para o cálculo de índices de avaliação das condições de estabilidade de tensão, enquanto que, usando circuito equivalente de Thévenin encontrou-se um método que funciona corretamente para barra de carga terminal, barra não-terminal e barra de tensão controlada por gerador. / [en] The emergence of voltage stability phenomenon in the operation of power systems has motivated hundreds of researchers to develop methods to detect the proximity to voltage instability, with computational efficiency and to take all necessary and appropriate measures to ensure reliable and safe operation. In this work, different methods that allow transforming large systems into simple circuits were analyzed, such as the equivalent circuit between generators and loads, based on the calculation of short-circuit currents; the network reduction technique for eliminating intermediate buses; and the Thévenin equivalent. The application of these equivalents on voltage stability assessment of 3 and 4 bus testing systems were extensively tested. At the end, it was verified that that the equivalent circuit between the generator and load, and the network reduction technique, cannot be used for calculating the voltage stability conditions evaluation indexes. However, using Thévenin equivalent circuit, it was found a proper method, which works correctly for terminal buses, transit buses and voltage-controlled buses.

Switching from fossil-fuel-powered vehicles to electric vehicles has become an international focus in the pursuit of combatting climate change. Regardless, the adoption of electric vehicles has been slow, in part, due to range anxiety. One solution to mitigating range anxiety is to provide a more accurate state of charge (SOC) and range estimation. SOC estimation of lithium-ion batteries for electric vehicle application is a well-researched topic, yet minimal tools and code exist online for researchers and students alike. To that end, a publicly available Kalman filter-based SOC estimation function is presented. The MATLAB function utilizes a second-order resistor-capacitor equivalent circuit model. It requires the SOC-OCV (open circuit voltage) curve, internal resistance, and equivalent circuit model battery parameters. Users can use an extended Kalman filter (EKF) or adaptive extended Kalman filter (AEKF) algorithm and temperature-dependent battery data. A practical example is illustrated using the LA92 driving cycle of a Turnigy battery at multiple temperatures ranging from -10C to 40C. Current range estimation methods suffer from inaccuracy as factors including temperature, wind, driver behaviour, battery voltage, current, SOC, route/terrain, and much more make it difficult to model accurately. One of the most critical factors in range estimation is the battery. However, most models thus far are represented using equivalent circuit models as they are more widely researched. Another limitation is that any machine learning-based range estimation is typically based on historical driving data that require odometer readings for training. A range estimation algorithm using a machine learning-based voltage estimation model is presented. Specifically, the long short-term memory cell in a recurrent neural network is used for the battery model. The model is trained with two datasets, classic and whole, from the experimental data of four Tesla/Panasonic 2170 battery cells. All network training is completed on SHARCNET, a resource provided by Canada Compute to researchers. The classically trained network achieved an average root mean squared error (RMSE) of 44 mV compared to 34 mV achieved by the network trained on the whole dataset. Based on the whole dataset, all test cases achieve an end range estimation of less than 5 km with an average of 0.29 km. / Thesis / Master of Applied Science (MASc)

Canada's aviation industry aims to reduce its carbon footprint while maintaining safety and operational standards. Hybrid and electric aircraft offer a promising solution to reducing the environmental impact of conventional aviation. However, current limitations in battery technology and the robustness of battery management systems in monitoring and estimating battery states cause significant challenges for their adoption in aviation applications. This research focuses on developing an advanced state of charge (SoC) estimation method for Li-ion batteries used in hybrid aircraft. A new approach is proposed that integrates a merged set of equivalent circuit models capable of simulating battery dynamics at both the cell and module levels. In addition, an innovative dual filter involved in interactive multiple model (IMM) frameworks is introduced, equipped with advanced filtering approaches such as smooth variable structure filter (SVSF). This framework ensures accurate SoC estimation even under varying and harsh operating conditions by testing all developed algorithms in real-time. The developed model is much more accurate than the existing SoC estimation algorithms in the aircraft battery management system. These findings increase the understanding of battery performance in specific aviation conditions and help develop safer and more advanced condition monitoring and estimation methods for hybrid and electric aircrafts. / Thesis / Master of Applied Science (MASc)

Solid-state supercapacitors (SSCs) consist of porous carbon electrodes and gel-polymer electrolytes and are used in novel energy storage applications. The current study aims to simulate the impedance of SSCs using a clearly defined equivalent circuit (EC) model with the ultimate goal of improving their performance. To this end, a conventional mathematical and a physicochemical model were adapted. The impedance was measured by electrochemical impedance spectroscopy (EIS). An EC consisting of electrical elements was introduced for each modeling approach. The math- ematical model was purely based on a best-fit method and utilized an EC with intuitive elements. In contrast, the physicochemical model was motivated by advanced theories and allowed meaningful associations with properties at the electrode, the electrolyte, and their interface. The physicochemical model showed a higher approximation ability (relative error of 3.7%) due to the interface impedance integration in a more complex circuit design. However, this model required more modeling and opti- mization effort. Moreover, the fitted parameters differed from the analytically calculated ones due to uncertainties in the SSC’s microscale configuration, which need further investigations. Nevertheless, the results show that the proposed physicochemical model is promising in simulating EIS data of SSCs with the additional advantage of utilizing well-reasoned property-based EC elements.

The theoretical part presents a literature review about the basis of the impedance spectroscopy method, its main measurement and analysis schemes, as well as the application of the method in the study of memristive structures. In the practical part a virtual device “VI ImpSpec” based on “National Instruments” equipment on I-V method of complex impedance measurement is developed. Approbation of the virtual device on RC-circuits and its application in the study of memristive structures based on Zr/ZrO2/Au is carried out. During approbation assumed structure of equivalent circuits from RC-circuits is confirmed, as well as the presence of inductive components in them. Research methods: optical microscopy, impedance spectroscopy. / В теоретической части представлен литературный обзор основы метода импедансной спектроскопии, его основных схем измерения и анализа, а также применение метода в исследовании мемристивных структур. В практической части разработан виртуальный прибор «VI ImpSpec» на базе оборудования «National Instruments» по I-V методу измерения комплексного сопротивления. Проведена апробация виртуального прибора на RC-цепях и его применение в исследовании мемристивных структур на основе Zr/ZrO2/Au, в ходе которых подтверждается предполагаемая структура эквивалентных схем из RC-цепей, а также наличие индуктивных составляющих в них. Методы исследования: оптическая микроскопия, импедансная спектроскопия.

Dans le cadre du développement des véhicules électriques et hybrides, la connaissance et la gestion de l'énergie du pack de batteries est une problématique majeure. Pour cela, les constructeurs automobiles ont besoin de modèles numériques pour représenter le comportement dynamique des batteries. L'objectif de cette thèse est de développer, d'une part une méthodologie de caractérisation du comportement dynamique des cellules de batterie et de leurs assemblages et d'autre part des modèles numériques associés qui soient simples, rapides, robustes, présentant le meilleur compromis précision/simplicité. La première partie du travail de la thèse a consisté à développer une nouvelle méthode de caractérisation expérimentale avec un modèle de circuit électrique équivalent, qui permet de s'appliquer facilement à différentes batteries et de calibrer la complexité du modèle (nombre de circuits utilisés) en fonction de la durée des mesures de la phase de repos après une sollicitation. Le modèle généré est capable de suivre les évolutions rapides et lentes de la tension de la batterie, ce qui peut améliorer l'estimation de la tension dans les applications BMS (Battery Management System). Des essais de validations sur différentes batteries ont montré que les modèles générés permettent une prédiction précise du comportement dynamique de la batterie. Ensuite, le manuscrit aborde les assemblages des cellules en série avec la méthode de caractérisation élaborée. Elle commence par une définition énergétique de l'assemblage. Puis, la modélisation de l'assemblage avec la méthode de caractérisation est discutée. Les essais de validation ont été menés sur différents assemblages et ont montré que le comportement dynamique de l'assemblage peut aussi être bien représenté avec les modèles identifiés / As part of the development of electric and hybrid vehicles, energy management in the battery pack is a major issue. Car manufacturers need a numerical model to represent the dynamic behavior of batteries. The objective of this work is to develop, on the one hand, a characterization method of the dynamic behavior of battery cells and their assemblies, and on the other hand the combined numerical models which are simple, fast, robust and with the best accuracy/simplicity compromise. The first part of the work is dedicated to develop a new experimental characterization method with an equivalent circuit model, which can be applied easily to different battery cells and allows calibrating the complexity of the model (number of the RC circuits) according to the measurement duration of the resting phase after a solicitation. Therefore, the generated model is able to follow the rapid and slow voltage change of the battery cell, which improves voltage and state of charge estimation for the BMS (Battery Management System) applications. The validation tests on different battery cells show that the generated model allows accurate prediction of the battery cell’s dynamic behavior. The second part of the work studies the cell assemblies with cells connected in series. It begins with an energy definition of the cell assembly. Then modelling of the assembly with the developed characterization method is discussed. The validation tests were carried out on different assemblies and show that the dynamic behavior of the assembly can be also well represented with the identified models

Actuellement, le développement de semiconducteurs et la demande croissante de convertisseurs en électronique de puissance dans les différents domaines de l’énergie électrique, notamment pour des applications dans l’aéronautique et les réseaux de transport et de distribution, imposent de nouvelles spécifications comme le fonctionnement à hautes fréquences de commutation, densités de puissance élevées, hautes températures et hauts rendements. Tout ceci contribue au fort développement des composants en SiC (Carbure de Silicium). Cependant, ces composants créent de nouvelles contraintes en Compatibilité Electromagnétique (CEM) à cause des conditions de haute fréquence de commutation et fortes vitesses de commutation (forts di/dt et dv/dt) en comparaison à d’autres composants conventionnels de l'électronique de puissance. Une étude des perturbations générées par les composants SiC est donc nécessaire. L'objectif de ce travail est de donner aux ingénieurs amenés à concevoir des convertisseurs une méthode capable de prédire les niveaux d'émissions conduites générées par un convertisseur électronique de puissance qui intègre des composants en SiC. La nouveauté du travail présenté dans cette thèse est l’intégration de différents modèles de type circuit pour tous les constituants d’un convertisseur (un hacheur série est pris comme exemple). Le modèle est valable pour une gamme de fréquences de 40Hz à 30MHz. Des approches de modélisation des parties passives du convertisseur sont présentées. Ces approches sont différentes selon que les composants modélisés soient disponibles ou à concevoir : elles sont basées sur des mesures pour la charge et les capacités ; elles sont basées sur des simulations prédictives pour routage du convertisseur. Le modèle complet du convertisseur (éléments passifs et actifs) est utilisé en simulation pour prédire les émissions conduites reçues dans le réseau stabilisateur d’impédance de ligne. Le modèle est capable de prédire l'impact de différents paramètres comme le routage, les paramètres de contrôle comme les différents rapports cycliques et les résistances de grille avec des résultats satisfaisants dans les domaines temporels et fréquentiels. Les résultats obtenus montrent que le modèle peut prédire les perturbations en mode conduit pour les différents cas jusqu'à une fréquence de 15MHz. Finalement, une étude paramétrique du convertisseur a été élaborée. Cette étude a permis de voir l’influence de la qualité des différents modèles comme les éléments parasites du routage, des composants passifs et actifs et d'identifier les éléments qui ont besoin d’un modèle précis pour avoir des résultats valides dans la prédiction des perturbations conduites. / The recent technological progress of semiconductors and increasing demand for power electronic converters in the different domains of electric energy particularly for applications in aeronautics and networks of transport and distribution impose new specifications such as high frequencies, high voltages, high temperatures and high current densities. All of this contributes in the strong development of SiC (Silicon Carbide) components. However these components create new issues in Electromagnetic Compatibility (EMC) because of the conditions of high frequency switching and high commutation speeds (high di/dt and dv/dt) compared to other conventional components in power electronics. A precise study of the emissions generated by SiC components is therefore necessary. The aim of this work is to give a method able to predict levels of conducted emissions generated by a power electronics converter with SiC components to engineers which design power converters. The novelty of the work presented in this thesis is the integration of different modeling approaches to form a circuit model of a SiC-based converter (a buck dc–dc converter is considered as an example). The modeling approach is validated in the frequency range from 40Hz to 30MHz. Modeling approaches of the passive parts of the converter are presented. Theses approaches differs according to whether the component is existing or to be designed : they are based on measurements for the load and capacitors; they are based on numerical computation and analytical formulations for PCB. The complete model obtained (passive and active components) is used in simulations to predict the conducted emissions received by the line impedance stabilization network. The model is able to predict the impact of various parameters such as PCB routing, the control parameters like duty cycles and different gate resistors in the time and frequency domains. A good agreement is obtained in all cases up to a frequency of 15MHz. Finally, a parametric study of the converter has been elaborated. This study allowed to see the influence of different models such as parasitic elements of the PCB, passive and active components and to identify the elements that need a precise model to obtain valid results in the prediction of conducted EMI.

La récupération d'énergie par élément piézoélectrique est une technique prometteuse pour les futurs systèmes électroniques nomades autoalimentés. L'objet de ce travail est d’analyser des approches simples et agiles d’optimisation de la puissance produite par un générateur piézoélectrique. D'abord le problème de l’optimisation de l’impédance de charge d’un générateur piézoélectrique sismique est posé. Une analyse du schéma équivalent global de ce générateur a été menée sur la base du schéma de Mason. Il est démontré que la puissance extraite avec une charge complexe adaptée puisse être constante quelle que soit la fréquence et que de plus elle est égale à la puissance extraite avec la charge résistive adaptée du même système sans pertes. Il est montré toutefois que la sensibilité de cette adaptation à la valeur de la réactance de la charge la rend difficilement réaliste pour une application pratique. Une autre solution pour améliorer l’énergie extraite est de considérer un réseau de générateurs positionnés en différents endroits d’une structure. Des simulations sont proposées dans une configuration de récupération d’énergie de type directe sur une plaque encastrée. Les générateurs piézoélectriques, associés à la technique SSHI, ont été reliés selon différentes configurations. Les résultats attestent que l’énergie produite ne dépend pas de façon critique de la manière dont sont connectés les éléments. Toutefois l’utilisation d’un seul circuit SSHI pour l’ensemble du réseau dégrade l’énergie extraite du fait des interactions entre les trop nombreuses commutations. Enfin une nouvelle approche non-linéaire est étudiée qui permet l’optimisation de l’énergie extraite tout en gardant une grande simplicité et des possibilités d’auto alimentation. Cette technique appelée S3H pour « Synchronized Serial Switch Harvesting » n’utilise pas d’inductance et consiste en un simple interrupteur en série avec l’élément piézoélectrique. La puissance récupérée est le double de celle extraite par les méthodes conventionnelles et reste totalement invariante sur une large gamme de résistances de charge. / Piezoelectric energy harvesting is a promising technique for battery-less miniature electronic devices. The object of this work is to evaluate simple and robust approaches to optimize the extracted power. First, a lightweight equivalent circuit derived from the Mason equivalent circuit is proposed. It’s a comprehensive circuit, which is suitable for piezoelectric seismic energy harvester investigation and power optimization. The optimal charge impedance for both the resistive load and complex load are given and analyzed. When complex load type can be implemented, the power output is constant at any excitation frequency with constant acceleration excitation. This power output is exactly the maximum power that can be extracted with matched resistive load without losses. However, this wide bandwidth optimization is not practical due to the high sensitivity the reactive component mismatch. Another approach to improve power extraction is the capability to implement a network of piezoelectric generators harvesting on various frequency nodes and different locations on a host structure. Simulations are conducted in the case of direct harvesting on a planar structure excited by a force pulse. These distributed harvesters, equipped with nonlinear technique SSHI (Synchronized Switching Harvesting on Inductor) devices, were connected in parallel, series, independently and other complex forms. The comparison results showed that the energy output didn’t depend on the storage capacitor connection method. However, only one set of SSHI circuit for a whole distributed harvesters system degrades the energy scavenging capability due to switching conflict. Finally a novel non-linear approach is proposed to allow optimization of the extracted energy while keeping simplicity and standalone capability. This circuit named S3H for “ Synchronized Serial Switch Harvesting” does not rely on any inductor and is constructed with a simple switch. The power harvested is more than twice the conventional technique one on a wide band of resistive load.