Volvo Construction Equipment AB, Volvo CE, är en global tillverkare av entreprenadmaskiner. Detta exjobb fokuserar på batterierna i dessa entreprenadmaskiner som försörjer maskinens elsystem och startmotor vid start. Med dagens teknik ställs nya krav på strömförsörjning i entreprenadmaskiner. Den största skillnaden är att förbrukare är igång när motorn är avstängd och strömförsörjningen kommer enbart från batteriet. Ett startbatteri av bly-syra typ är inte konstruerad för detta användningsfall. Volvo CE jobbar därför med att ta fram kunskap om hur laddningen i batterierna används och cyklas under drift. Frågeställning om vilka parametrar och trender som är relevanta för att utvärdera batteriladdning har behandlats i detta arbete. Bakomliggande teori har undersökts, förklarats och vidareutvecklats i beskrivningen av den föreslagna metodiken för analys av batteriladdningsnivå i entreprenadmaskiner. En metod för hur identifierad relevant mätdata skall extraheras ur entreprenadmaskinerna har beskrivits i samband med beskrivningen av den utvecklade och framtagna prototyputrustningen. Den i detta arbete föreslagna analysmetodiken för dimensionering av batterikapacitet och tillämpad på mätdata från batteriladdningen under driftsmässiga förhållanden för entreprenadmaskiner kan också hjälpa till att ge svar på om de batterier som idag används av Volvo CE är lämpliga i den nya generationens entreprenadmaskiner. Arbetet innehåller ett nyhetsvärde för Volvo CE och andra då den föreslagna analysmetodiken inte beskrivits eller tillämpats tidigare på Volvo CE. Arbetet ger också förslag på hur man kan gå vidare i kunskapsuppbyggnaden och utvecklingsarbetet kring batterier inom Volvo CE. / Volvo Construction Equipment AB, Volvo CE, is a global producer of construction machines. This thesis has focus on the battery in these machines that are providing power to the electrical system and start engine during cranking. With today’s technology there are new demands on the power supply in construction machines. The largest difference is in the demand for power when the engine is off and the only power source is the battery. A Lead-Acid starter battery is not constructed for this type of demand. Because of this Volvo CE has begun to build knowledge about how the charge in the battery is used and cycled during usage. This thesis has processed questions about which parameters and trends that are relevant to evaluate regarding the level of charge in the battery. The theory behind these parameters has been examined, described and evolved in the suggested methodology for analysis of the level of charge in the battery in construction machines. A method on how to extract identified data from the construction machines has been described in the work on the prototype equipment for collecting the data. The suggested methodology in this thesis to analyse the level of charge in the battery in construction equipment based on the user case may help to give answer to the question if the batteries used today are suitable for the new generation of construction machinery. This thesis contains a news value for Volvo CE and others since this methodology has not been described or used before at Volvo CE. The thesis also provide suggestion for a road to build more knowledge on batteries within Volvo CE.

Tesis para optar al grado de Doctora en Ingeniería Eléctrica / La disponibilidad de energía es una de las limitaciones que presentan las Redes de Sensores Inalámbricas (WSN, Wireless Sensor Network). Tradicionalmente, las baterías han sido utilizadas para proveer energía a los nodos de sensores y al tener una vida útil limitada afectan el tiempo de vida de la red. Soluciones como el uso de baterías de gran tamaño o el reemplazo de ellas no son viables, debido al gran número de sensores que componen la red y a que pueden ser desplegados en zonas de difícil acceso. Esta situación ha motivado que las soluciones para la conservación de la energía en las WSNs se enfoquen en el desarrollo de técnicas que actúen a nivel de las capas física y de enlace de datos, como es el caso de los protocolos de Control de Acceso al Medio (MAC, Medium Access Control). Los protocolos MAC son una de las soluciones ampliamente estudiadas y utilizadas porque permiten un equilibrio entre la conservación de energía y otros parámetros críticos de la red, como el rendimiento, latencia, reducción de colisiones y mensajes de control. También tienen la facilidad de adaptarse a las nuevas aristas de trabajo que surgen al incorporar nuevas tecnologías como lo son los Dispositivos de Recolección de Energía (EHD, Energy Harvesting Device). Otro aspecto que está siendo considerado y estudiado en el diseño de los protocolos MAC es la información que se puede extraer de la batería, ya que al estimar la capacidad disponible de la misma, el mecanismo del Duty Cycling (DuC) puede ser ajustado con el propósito de aumentar la eficiencia energética y por lo tanto, extender la vida útil de la red. Es necesario desarrollar técnicas que incorporen un mecanismo de conservación de energía que integre información de la batería a través de indicadores como el Estado de Carga (SOC, State of Charge) y Estado de Salud (SOH, State of Health) para mejorar la eficiencia energética en WSN. La idea de incorporar información de la batería se debe a que la capa MAC está a cargo de controlar los modos de operación del nodo sensor, lo que está directamente relacionado con la cantidad de corriente exigida a la batería. Conocidos los perfiles de uso de la batería es posible estimar los indicadores SOC y SOH que se han utilizado ampliamente en diversas aplicaciones para conocer la cantidad de energía disponible en la batería y la degradación que ha sufrido la misma. En este trabajo se propuso el desarrollo de un protocolo que actúa en la subcapa MAC y que considera la información de la batería para tomar decisiones con respecto al tiempo activo y de reposo del nodo de sensor, con la finalidad de promover el uso eficiente de la energía y extender la vida útil de la red. Los resultados obtenidos validan esta nueva propuesta de algoritmo y establecer pautas para guiar el diseño de protocolos MAC que se centren en minimizar el consumo de energía teniendo en cuenta los dispositivos de recolección de energía y la información de la batería.

Magíster en Ciencias de la Ingeniería, Mención Eléctrica / Ingeniero Civil Eléctrico / Actualmente existe una gran cantidad de equipos y dispositivos que utilizan baterías como su fuente primaria o secundaria de energía. Para estos sistemas es crítico contar con información del desempeño de sus baterías, dado que este conocimiento puede ayudar a tomar decisiones apropiadas y asegurar autonomía en el tiempo. Dos importantes variables que deben ser monitoreadas son el "Estado-de-Salud" (SOH, del inglés State-of-Health) y el "Estado-de-Carga" (SOC, del inglés State-of-Charge). Este trabajo se enfoca en generar esquemas de pronóstico para ambas variables, donde se tome en cuenta la temperatura de operación. Con este propósito, se diseñaron y realizaron un conjunto de pruebas de laboratorio con celdas de Ion-Litio donde se caracterizó el impacto de la temperatura en factores tales como la energía entregada en un ciclo, la impedancia interna, o tendencia de degradación. A partir de estos datos, y esquemas existentes en la literatura, se proponen modelos empíricos para la degradación y para la descarga de una batería mediante una representación de espacio-estados, definiendo directamente un estado como el SOH y el SOC respectivamente. Las estimaciones y predicciones a largo plazo se efectúan bajo un enfoque Bayesiano, basado en el filtro de partículas. Además, se propone la implementación de lazos de control externos para corregir condiciones iniciales erróneas de los estados, y un módulo de detección de outliers para trabajar con datos perdidos o inválidos. La validación de estos esquemas se realiza con datos generados en laboratorio, además de datos de degradación publicados por NASA Ames Prognostic Center of Excellence. El esquema propuesto para el SOH es capaz de incorporar explícitamente el efecto de la temperatura de operación (bajo el concepto de "Capacidad Usable"), y estimar y pronosticar el SOH a una temperatura de referencia. Por otro lado, el esquema para el SOC fue validado incluyendo una mejor representación de la fenomenología del proceso de descarga comparada a la existente, y se deja una propuesta de cómo incluir el efecto de la temperatura en el modelo. La implementación de estos esquemas de pronóstico permite la incorporación de la temperatura de operación, que a pesar de su gran influencia en el comportamiento de las baterías es considerada constante en muchos casos presentes en la literatura; además de incluir algunas mejoras prácticas en los algoritmos de estimación. Las propuestas de este trabajo dejan las bases para avanzar en la incorporación de otros fenómenos importantes como la profundidad de descarga, o la magnitud de la corriente de descarga.

Ce mémoire traite de la modélisation électrique des accumulateurs lithium-ion, de l’estimation de leur état de charge (SOC) et de leur état de santé (SOH). Le premier chapitre revient sur les généralités concernant la technologie lithium-ion : caractéristiques, performances, constitution de l’élément de stockage, choix et nature des électrodes, conséquences qui en découlent d’un point de vue énergétique. Le principe de fonctionnement et les équations générales des phénomènes électrochimiques sont aussi développés. Des exemples d’application dans différents secteurs industriels sont ensuite proposés pour plusieurs gammes de puissance et d’énergie. Le second volet aborde la modélisation électrique des accumulateurs lithium-ion. Pour une meilleure compréhension des phénomènes complexes mis en jeu au sein des batteries, des éléments de modélisation physique sont exposés. Puis nous envisageons une synthèse des différents modèles de nature électrique rencontrés dans la littérature. Sur la base de campagnes de mesures menées sur un élément lithium-ion de 6,8 Ah, nous proposons, dans un troisième chapitre, notre propre modèle électrique équivalent valable pour les phases de décharge et de relaxation. En particulier nous déclinons plusieurs solutions pour distribuer l’énergie et rendre compte des différents effets de ligne. Les outils de caractérisation et les procédures d’extractions des paramètres sont traités en détail. Dans un dernier chapitre nous étudions les possibilités d’estimer en ligne l’état de charge (SOC) et l’état de santé (SOH) d’un élément lithium-ion en cours d’exploitation. Après un bref rappel des méthodes académiques et industrielles actuelles, nous nous orientons vers l’emploi d’un filtre de Kalman. Afin d’estimer ses performances par rapport au coulombmètre, nous proposons un modèle et un algorithme que nous évaluons par simulation et testons sur élément réel / This dissertation of thesis deals with the electrical modelling of lithium-ion accumulators and the determination of both state-of-charge (SOC) and state-of-health (SOH). The first chapter is focused on generalities about lithium-ion technology: characteristics, qualities, constitution of the storage device, choice and nature of the electrodes and their consequences on energetical features. The principle and the general equations of the electrochemical phenomena are developed as well. Application examples from different industrial areas are displayed for several power and energy ranges. The second section is about the electrical modelling of lithium-ion accumulators. With a view to better understand the complex electrochemical phenomena, elements of physical modelling are proposed. Then, the synthesis of different electrical models released in the press is considered. On the basis of experimental campaigns lead on a 6.8 Ah lithium-element, we proposed, in a third chapter, our own equivalent electrical model suitable for both discharge phases and relaxation period. In particular, we depict several alternatives to distribute the energy and describe the different line effects. Both characterization tools and parameters extraction procedure are clearly detailed. In the last section, we tackle both SOC and SOH on-line determination. After a short review of academicals and industrial solutions, we rapidly head towards the use of a Kalman filter. In order to compare its features versus the coulombmeter, we propose a model and an algorithm, numerical simulations and experimental tests are performed

Philosophiae Doctor - PhD / Proton exchange membrane fuel cells (PEMFC) converts chemical energy from the electrochemical reaction of oxygen and hydrogen into electrical while emitting heat, oxygen depleted air (ODA) and water as by-products. The by-products have useful functions in aircrafts, such as heat that can be used for ice prevention, deoxygenated air for fire retardation and drinkable water for use on board. Consequently, the PEMFC is also studied to optimize recovery of the useful products. Despite the progress made, durability and reliability remain key challenges to the fuel cell technology. One of the reasons for this is the limited understanding of PEMFC behaviour in the aeronautic environment. The aim of this thesis was to define a comprehensive non-intrusive diagnostic technique that provides real time diagnostics on the PEMFC State of Health (SoH). The framework of the study involved determining factors that have direct influence on fuel cell life in aeronautic environment through a literature survey, examining the effects of the factors by subjecting the PEMFC to simulated conditions, establishing measurable parameters reflective of the factors and defining the diagnostic tool based on literature review and this thesis finding.

Operating batteries in parallel is attempted to overcome the problems with conventionally used battery bank, in which batteries are connected in series. The problems and the management with the operation of serial connected batteries are first addressed. The related topics to the parallel configuration are reviewed. Then, the parallel configuration with battery power modules is proposed. The battery power module can be realized with different dc-to-dc converters for different applications. When batteries are charged in parallel, the problem of over-charge can be avoided. With parallel operation, the discharging currents of the batteries are independently controlled but are coordinated to execute a full amount load current. This allows for scheduling the discharging profiles under different operating conditions. As a result, a sophisticated discharging profile can be realized to utilize the available stored energy in batteries. On the other hand, some of the batteries may take rest or be isolated from the system for the detections at a time. This facilitates the estimations of the state of charge (SOC) and the state of health (SOH). Moreover, the completely exhausted or damaged batteries can be isolated from the battery power supply bank without interrupting the system operation. Experiments are carried out on battery power modules with lead-acid batteries incorporating with associated buck-boost converters. The experimental results demonstrate that a more efficient utilization of battery energy can be achieved. On the other hand, a more reasonable management can be done with simple estimation methods of the SOC and the SOH.

This thesis proposes an enhanced ampere-hour counting method based on the depth-of-discharge (DOD) to estimate the state-of-charge (SOC) and state-of-health (SOH) for lead-acid batteries. Not only the losses at different discharging currents, but also the releasable capacity at the exhausted state caused by the larger discharging current are considered and compensated. Furthermore, the SOH is revaluated at the exhausted state by the maximum releasable capacity, consequently leading to more accurate SOC estimation. Through the experiments that emulate practical operations, the experimental results reveal that the maximum error is less than 6 %.

A novel battery power system configured by the battery power modules (BPMs) is proposed. Each BPM consists of a single battery pack or a battery bank equipped with an associated DC/DC converter. The output ports of BPMs can be connected in series for the high voltage applications, or in parallel to cope with a higher power or energy. For a large scale battery power system, a number of BPMs can be arrayed with combination of series and parallel connections to meet the load requirements. These all configurations allow the BPMs be operated individually. Consequently, the discharging currents of the batteries can be independently controlled, but coordinated to provide a full amount of the load current. The performances of BPMs connected in both parallel and series at outputs are analyzed theoretically and discussed from the experimental results. Batteries operating independently do not suffer from charge imbalance, and thus can avoid being over-charged or over-discharged, so that the life cycle can be prolonged. Furthermore, sophisticated discharging profiles such as intermittent currents can be realized to equalize the charges and thus to efficiently utilize the available stored energy in batteries. During the operation period, some of the batteries may take rest or be isolated from the system for the open-circuit measurement, facilitating the estimation of the state-of-charge (SOC) and the evaluation of the state-of-health (SOH). With the benefit of independent operation, the BPMs can be discharged with a scheduled current profile, such as intermittent discharging. The investigation results show that the average current plays the most important role in current discharging. By detecting the battery voltage at the break time, an SOC estimation method based on the dynamically changed open-circuit voltage exhibits an acceptable accuracy in a shorter time with considerations of the previous charging/discharging currents and the depth-of- discharge (DOD). In addition, the coulomb counting method can be enhanced by evaluating the SOH at the exhausted and fully charged states, which can be intended on the independently operated BPMs. Through the experiments that emulate practical operations, the SOC estimation methods are verified on lead-acid batteries and lithium-ion batteries to demonstrate the effectiveness and accuracy.

In this paper, a state of charge (SOC) and a state of health (SOH) estimation method for lead-acid batteries are presented. In the algorithm the measurements of battery’s terminal voltage, current and temperature are used in the process of SOC calculation. The thesis was written in cooperation with Micropower AB. The algorithm was designed to fulfill the specific requirements of the electric vehicles application: an error below 5% of SOC, computational simplicity and the possibility of being implemented in a basic programming languages. The current used method at Micropower, Coulomb counting, is compared with a method presented by Chiasson and Vairamohan 2005 based on modified Thevein circuit during charging and discharging of the battery. The Thevenin based method gave better result compared to Coulomb counting but seems not to fulfill Micropowers requirements. A correction method based on periods of no charging or discharging, possible to be used together with Coulomb counting as well as with the Thevenin method was developed. The evaluation method indicates that when using also the correction method the Micropowers requirements are fulfilled. / I detta papper, är ett laddningstillstånd (SOC) och hälsotillstånd (SOH) skattningsmetod för blybatterier presenteras. I algoritmen mätningarna av batteriets polspänning, ström och temperatur används i processen för SOC beräkning. Avhandlingen är skriven i samarbete med Micropower AB. Algoritmen har utformats för att uppfylla de särskilda kraven för elektriska fordon: ett fel under 5% av SOC, computational enkelhet och möjligheten att genomföras i ett grundläggande programmeringsspråk. Den nuvarande metoden vid Micropower, Coulomb räkning, jämförs med en metod som presenteras av Chiasson och Vairamohan 2005 baserad på modifierad Thevein kretsen under laddning och urladdning av batteriet.

This is a dissertation about urban systems; within this broad subject I tackle three issues, one that focuses on an observed inter-city relationship and two that focus on an intra-city phenomenon. In Chapter II I adapt a model of random emergence of economic opportunities from the firm growth literature to the urban dynamics situation and present several predictions for urban system dynamics. One of these predictions is that the older the city the larger and more diversified it is going to be on average, which I proceed to verify empirically using two distinct datasets. In Chapter III I analyze the Residential Real Estate Bubble that took place in Miami-Dade County from 1999 to 2006. I adopt a Spatial-Economic model developed for the Paris Bubble episode of 1984-1993 and formulate an innovative test of the results in terms of speculative intensity on the basis of proxies of investor activity available in my dataset. My results support the idea that the best or more expensive areas are also where the greatest speculative activity takes place and where the rapid increase in prices begins. The most significant departure from previous studies that emerges in my results is the absence of a wider gap between high priced areas and low priced areas in the peak year. I develop a measure of dispersion in value among areas and contrast the Miami-Dade and Paris episodes. In Chapter IV I analyze the impact on tax equity of a Florida tax-limiting legislation known as Save Our Homes. I first compare homesteaded and non-homesteaded properties, and second, look within the subset of homesteaded properties. I find that non- homesteaded properties increase their share of taxes paid relative to homesteaded properties during an up market, but that this is reversed during a down market. For the subset of homesteaded properties I find that the impact on tax equity of SOH will depend on differential growth rates among higher and lower valued homes, but during times of rapid home price appreciation, in a scenario of no differential growth rates in property values, SOH increases progressivity relative to the prior system.