The work deals with relatively new components allowing electric energy accumulation – ultracapacitors. It focuses on their application in traffic systems – in independent electric vehicles. Design and verification of a system with ultracapacitor and DC/DC adaptive converter was done. Control of the adaptive converter modifies very positively the time wafeform of the traction accumulator current during the drive cycle. The designed connection of ultracapacitor and DC/DC converter implemented in the drive structure of experimental electric vehicle with induction machine contributes to increment the action radius of the vehicle by 16% (determined by experimental verification). This result was achived particularly by limitation of traction accumulator current peaks, And by more effective storage of energy gained by recuperative braking of the vehicle as well. The core of the system is a control of the adaptive converter in order to provide an active filtration of the accumulator’s current to its long-period mean value, i.e. elimination of current (power) peaks. These are caused by acceleration from non-zero initial vehicle speed or by recuperative braking. This is done by a subsidiary current loop. The converter has a superior voltage regulation loop, which sets in long-time period the voltage of ultracapacitors to the proper value – indirectly dependent on the speed of the vehicle. This ensures the appropriate energy management of the ultracapacitor. In the following, properties of test set of ultracapacitors were verified. Finally, methods of suppression of capacity variability influence in series connection of these components were compiled and critically reviewed.

Esta tese de doutorado visa o estudo e o desenvolvimento de topologias e técnicas de controle para a integração de fontes alternativas tais como, solar e eólica acopladas a um barramento comum em corrente continua (CC) e conectá-las à rede de distribuição. O sistema contará também com elementos armazenadores como bancos de baterias e ultracapacitores, formando assim uma estrutura híbrida de armazenamento. Algoritmos de gerenciamento de energia serão implementados para que o perfil de injeção de potência na rede seja suave, eliminando as oscilações que são criadas, naturalmente, por fontes dependentes de fatores climáticos. Como consequência, os sistemas formados por fontes alternativas podem se tornar confiáveis e previsíveis, melhorando a capacidade de planejamento em um cenário cujos sistemas apresentem uma participação elevada na matriz energética. Duas metodologias de gerenciamento de energia são executadas neste trabalho, na primeira o ultracapacitor é gerenciado de modo a permitir a transferência de potência constante para a rede de distribuição em intervalos da ordem de minutos. A segunda estratégia se baseia no uso de banco de baterias combinado com ultracapacitores, formando uma estrutura híbrida de armazenamento. Nessa estrutura de gerenciamento, os armazenadores se comunicam entre si de forma a realizar um compartilhamento e filtragem de energia, fazendo com que transitórios de potência não sejam transmitidos para a rede de distribuição. Nesta estratégia, as baterias são responsáveis pelo fornecimento/absorção da potência média enquanto os ultracapacitores se encarregam dos transitórios. No segundo instante outras duas metodologias de divisão de carga são propostas para microrredes híbridas, contudo são baseadas em estratégias descentralizadas, ou seja, os armazenadores não se comunicam entre si para realizar o compartilhamento. Resultados experimentais e simulações irão comprovar a efetividade das metodologias de gerenciamento propostas. / This Ph.D. dissertation aims the study and development of topologies and control techniques to integrate various alternative sources such as solar and wind, coupled to a direct current (DC) common bus and connect them to the distribution grid. Storage devices such as battery banks and ultracapacitors will form a hybrid storage structure that is responsible for the power supplying in periods in which the sources are unable (times of the day in which the light incidence is low or when the wind amount is scarce). Power management algorithms will be implemented so the alternative sources and storage devices exchange energy, in order to make smoother the power injection profile in the grid, eliminating the fluctuations that are created naturally by alternative sources. With a smooth power profile, energy management systems based on alternative sources may become more reliable and predictable, improving planning capacity in a scenario in which the renewable energy sources have a high penetration in the energy matrix. To obtain such a result, two power management methodologies are executed; the first one is based on ultracapacitors and aims to deliver constant power to the distribution network, even when the power production is zero. However, this technique allows constant power just for a few minutes, once the ultracapacitor capacity is limited. The second strategy is based on the bank of batteries combined with ultracapacitors, forming the hybrid storage system. In this management structure, the storage devices communicate with each other in order to perform a power sharing, resulting in a filtrated power profile delivered to the distribution network. In this strategy, the batteries are responsible to providing average power while ultracapacitors are in-charge of the transient power, sparing the batteries from supplying power peaks. In a second moment, two other load sharing methodologies are proposed for hybrid systems, but are based on decentralized techniques, i.e. storage devices do not communicate with each other to make the power sharing. Experimental and simulated results will prove the effectiveness of the control strategies and management methodologies.

L’intégration de panneaux photovoltaïques dans un système électrique réduit la consommation des sources fossiles et apporte des avantages environnementaux. Toutefois, l'intermittence et les fluctuations de puissance détériorent la qualité d’alimentation électrique. La solution proposée est d’ajouter des éléments de stockage, coordonnés par un contrôleur local qui gère les flux de puissance entre toutes les sources et la disponibilité énergétique. Ce générateur actif PV peut générer des références de puissance et fournir des services « système » au réseau électrique. Puis les concepts liés au micro réseau sont transposés pour concevoir un système central de gestion de l'énergie d'un réseau électrique résidentiel, qui est alimenté par des générateurs actifs PV et une micro turbine à gaz. Un réseau de communication est utilisé pour échanger des données et des références de puissance. Un système de gestion de l'énergie est développé avec différentes fonctions de contrôle sur des échelles de temps différentes afin de maximiser l'utilisation de l'énergie PV. Une planification opérationnelle quotidienne est conçue par un algorithme déterministe, qui utilise la prédiction d'énergie PV et de la charge. Puis ces références de puissance sont actualisées chaque demi-heure en tenant compte de la disponibilité de l’énergie PV et l’état des unités de stockage. Les erreurs de prévision et les incertitudes sont compensées par le réglage primaire de fréquence. Les résultats de simulation et les tests valident la conception de la commande du générateur actif photovoltaïque ainsi que le système central de gestion de l'énergie du réseau résidentiel étudié / The integration of PV power generation in a power system reduces fuel consumption and brings environmental benefits. However, the PV power intermittency and fluctuations deteriorate the power supply quality. A solution is proposed by adding energy storages, which are coordinated by a local controller that controls the power flow among all sources and implements an inner energy management. This PV based active generator can generate power references and can provide ancillary services in an electric network. Then micro grid concepts are derived to design a central energy management system of a residential network, which is powered by PV based active generators and a gas micro turbine. A communication network is used to exchange data and power references. An energy management system is developed with different time-scale functions to maximize the use of PV power. An operational daily planning is designed by a determinist algorithm, which uses 24 hour-ahead PV power prediction and load forecasting. Then power references are refreshed each half of an hour by considering the PV power availability and the states of energy storage units. Prediction errors and uncertainties are compensated by primary frequency controllers. Simulation and testing results validate the design of the PV active generator local controller and the central energy management system of the studied residential network

Esta tese de doutorado visa o estudo e o desenvolvimento de topologias e técnicas de controle para a integração de fontes alternativas tais como, solar e eólica acopladas a um barramento comum em corrente continua (CC) e conectá-las à rede de distribuição. O sistema contará também com elementos armazenadores como bancos de baterias e ultracapacitores, formando assim uma estrutura híbrida de armazenamento. Algoritmos de gerenciamento de energia serão implementados para que o perfil de injeção de potência na rede seja suave, eliminando as oscilações que são criadas, naturalmente, por fontes dependentes de fatores climáticos. Como consequência, os sistemas formados por fontes alternativas podem se tornar confiáveis e previsíveis, melhorando a capacidade de planejamento em um cenário cujos sistemas apresentem uma participação elevada na matriz energética. Duas metodologias de gerenciamento de energia são executadas neste trabalho, na primeira o ultracapacitor é gerenciado de modo a permitir a transferência de potência constante para a rede de distribuição em intervalos da ordem de minutos. A segunda estratégia se baseia no uso de banco de baterias combinado com ultracapacitores, formando uma estrutura híbrida de armazenamento. Nessa estrutura de gerenciamento, os armazenadores se comunicam entre si de forma a realizar um compartilhamento e filtragem de energia, fazendo com que transitórios de potência não sejam transmitidos para a rede de distribuição. Nesta estratégia, as baterias são responsáveis pelo fornecimento/absorção da potência média enquanto os ultracapacitores se encarregam dos transitórios. No segundo instante outras duas metodologias de divisão de carga são propostas para microrredes híbridas, contudo são baseadas em estratégias descentralizadas, ou seja, os armazenadores não se comunicam entre si para realizar o compartilhamento. Resultados experimentais e simulações irão comprovar a efetividade das metodologias de gerenciamento propostas. / This Ph.D. dissertation aims the study and development of topologies and control techniques to integrate various alternative sources such as solar and wind, coupled to a direct current (DC) common bus and connect them to the distribution grid. Storage devices such as battery banks and ultracapacitors will form a hybrid storage structure that is responsible for the power supplying in periods in which the sources are unable (times of the day in which the light incidence is low or when the wind amount is scarce). Power management algorithms will be implemented so the alternative sources and storage devices exchange energy, in order to make smoother the power injection profile in the grid, eliminating the fluctuations that are created naturally by alternative sources. With a smooth power profile, energy management systems based on alternative sources may become more reliable and predictable, improving planning capacity in a scenario in which the renewable energy sources have a high penetration in the energy matrix. To obtain such a result, two power management methodologies are executed; the first one is based on ultracapacitors and aims to deliver constant power to the distribution network, even when the power production is zero. However, this technique allows constant power just for a few minutes, once the ultracapacitor capacity is limited. The second strategy is based on the bank of batteries combined with ultracapacitors, forming the hybrid storage system. In this management structure, the storage devices communicate with each other in order to perform a power sharing, resulting in a filtrated power profile delivered to the distribution network. In this strategy, the batteries are responsible to providing average power while ultracapacitors are in-charge of the transient power, sparing the batteries from supplying power peaks. In a second moment, two other load sharing methodologies are proposed for hybrid systems, but are based on decentralized techniques, i.e. storage devices do not communicate with each other to make the power sharing. Experimental and simulated results will prove the effectiveness of the control strategies and management methodologies.

Les supercondensateurs sont des systèmes de stockage et de conversion de l'énergie électrochimique dont les densités de puissance et d'énergie sont supérieures à celles des batteries et des condensateurs diélectriques. L’optimisation de leurs performances requiert l’utilisation de matériaux d’électrode à grande surface spécifique tels que les carbones poreux. En particulier, il est possible d’obtenir des systèmes microporeux de porosité prédéterminée par la synthèse de répliques carbonées de zéolithes. Simuler un supercondensateur à l’échelle atomique permettrait de guider le choix des matériaux le composant. Nous avons étudié un système modèle comprenant deux électrodes en réplique carbonée de zéolithe Faujasite ainsi que d’un électrolyte représenté par un système de sphères chargées. Des calculs en Liaisons Fortes de la structure électronique de la matrice carbonée fournissent la distribution de charge dans les électrodes. L’adsorption des ions dans la porosité est étudiée via des simulations Monte Carlo, dans lesquelles les interactions entre ions sont traitées par l’intermédiaire de la méthode de la sommation d’Ewald pour la partie électrostatique, et par un potentiel de Lennard-Jones pour la partie chimique. Les charges sont redistribuées de façon auto-cohérente au cours de la simulation, et la matrice poreuse est relaxée sous l’influence de l’électrolyte. Nous avons pu ainsi mettre en évidence la façon dont les différents éléments (ions, atomes de carbone), et donc la charge, se répartissent à l’interface entre électrode et électrolyte. / Electric double-layer capacitors, also known as supercapacitors, are electrochemical capacitors that have an unusually high energy density compared to that of usual high-capacity electrolytic ones. Being generally admitted that storage density is improved through the use of a nanoporous materials, a good way to optimize supercapacitors, which require carbon materials, is to synthesise carbon replica with predetermined porosity from microporous materials such as zeolites. Modeling such supercapacitors at the atomic scale should help with the choice of its components. Our model system has both electrodes in zeolite carbon replica C-FAU, and has hard charged spheres as its electrolyte. Tight-binding calculations of the electronic structure of the carbon template give the charge distribution in the electrodes, while the absorption of the ions into the pores is studied through Monte Carlo simulations, in which the interactions between the ions are treated using Ewald summations for coulombic interactions and a Lennard-Jones short-range potential for chemical interactions. Relaxation of the electrodes under the influence of the electrolyte has been tested as well. This shows how charge and matter locate themselves at the electrode/electrolyte interface.

Práce se zabývá studiem superkondenzátorů (SC). Výstupem je detailní studie principů přenosu náboje ve struktuře SC, ukládání energie a nový náhradní model SC, který je založen na fyzikálních zákonitostech a principech SC. Dále byl vytvořen matematický model SC, který popisuje chování náboje v jeho aktivní vrstvě. SC byly testovány metodami umělého stárnutí. Závislosti poklesu parametrů SC vlivem různých metodik stárnutí jsou v práci shrnuty.

The transportation sector consumes around 70% of all petroleum in the US. In recent years, there have been improvements in the efficiency of the vehicles, and hybrid techniques that have been used to improve efficiency for conventional combustion vehicles. Hydraulic systems have been used as an alternative to conventional electric regenerative systems with good results. It has been proven that hydraulic systems can improve energy consumption in conventional combustion vehicles and in refuse collection vehicles. The control strategy has a large impact on the performance of the system and studies have shown the control strategy selection should be optimized and selected based on application. The performance of a hydraulic accumulator was compared with the performance of a set of ultracapacitors with the same energy storage capacity. The energy efficiency for the ultracapacitor was around 79% and the energy efficiency of the hydraulic accumulator was 87.7%. The power/mass ratio in the set of ultracapacitors was 2.21 kW/kg and 2.69 kW/kg in the hydraulic accumulator. The cost/power ratio is 217 US$/kW in the ultracapacitors and 75 US$/kW in the hydraulic accumulator. Based on these results, the hydraulic accumulator was selected as the energy storage device for the system. A testbench was designed, modeled, implemented to test the energy storage system in different conditions of operation. The experimental results of the testbench show how system can be actively controlled for different operating conditions. The operating conditions in the system can be adjusted by changing the number of rheostats connected to the electric generator. Different variables in the system were measured such as the angular shaft speed in the hydraulic pump, the torque and speed in the hydraulic motor, the pressure in the system, the flow rate, and the current and voltage in the electric generator. The control algorithm was successfully implemented, the results for the pressure in the system and the angular speed in the electric generator show how the control system can follow a desired reference value. Two different controllers were implemented: one controller for the pressure in the system, and one controller for the speed.

No description available.

This thesis deals with the design of Hybrid Energy Storage System (HESS) for Light Electric Vehicles (LEV) and EVs. More specifically, a tri-mode high-efficiency non-isolated half-bridge converter is developed for the LEV based HESS applications. A 2 kW, 100 V interleaved two-phase converter prototype was implemented. The peak efficiency of 97.5% and a minimum efficiency of 88% over the full load range are achieved. Furthermore, a power-mix optimizer utilizing the real-time Global Positioning System (GPS) data for the EV based HESS is proposed. For a specific design, it is shown that at the cost of less than 1.5% of the overall energy savings, the proposed scheme reduces the peak battery charge and discharge rates by 76% and 47%, respectively. A 30 kW bi-directional dc-dc converter is also designed and implemented for future deployment of the designed HESS into a prototype EV, known as A2B.

This thesis deals with the design of Hybrid Energy Storage System (HESS) for Light Electric Vehicles (LEV) and EVs. More specifically, a tri-mode high-efficiency non-isolated half-bridge converter is developed for the LEV based HESS applications. A 2 kW, 100 V interleaved two-phase converter prototype was implemented. The peak efficiency of 97.5% and a minimum efficiency of 88% over the full load range are achieved. Furthermore, a power-mix optimizer utilizing the real-time Global Positioning System (GPS) data for the EV based HESS is proposed. For a specific design, it is shown that at the cost of less than 1.5% of the overall energy savings, the proposed scheme reduces the peak battery charge and discharge rates by 76% and 47%, respectively. A 30 kW bi-directional dc-dc converter is also designed and implemented for future deployment of the designed HESS into a prototype EV, known as A2B.