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Design and implementation of a charge controller with buck converter topology for a Li-ion battery using the component LTC4015.Vidal Lorbada, Ricardo January 2016 (has links)
This report presents the process of design and implementation of a battery charger for a Li-ion battery. The development of this battery charger includes the component from Linear Technology LTC4015. This component integrates the functions of a battery charger configured as a buck (step-down) converter. This device must be integrated in a Printed Circuit Board with a specific design. Also, it must be configured using a microcontroller named Raspberry Pi, which also performs the measurements. The method of design is divided in two parts. One is focused on developing the printed circuit board, which includes the simulation of the device and the development of the PCB, and the second one is focused on developing the program used in the microcontroller to manage the operation of the LTC4015. The result is a charge controller device that can be used with different configurations with a buck converter topology. The different parts of the design process are the simulation, the design and the implementation. Each of these parts have a section of results in this report. The simulation section includes results obtained with LTSpice and the device LTC4020, which is a similar device to the LTC4015 but without the Maximum Power Point Tracking mode, which is not modelled in LTSpice. PV is the main power source considered to charge the battery, and is carefully studied in this project. The PV input is studied with LTSpice, first simulating the I-V curve of the schematic of the solar cell. Second, integrating a solar cell in the simulation of the LTC4015. Third, operating the device LTC4015 with a solar panel that is also characterized. The design section includes the electronic components used for the development of the board that integrates the charge controller, the LTC4015 in this case, based on the calculations performed for the requirements of the LTC4015. Finally, the implementation section includes the description of the board implemented but also the description of the configuration and measurement code. The conclusions presented in this report show that the LTC4015 is a battery buck charger with different functions that make it suitable to be used in different solar applications. Also, this report opens new future work lines, such as the full characterization of the board, the implementation of a test bench and the integration of the board in different applications for solar energy systems.
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Si/C Nanocomposites for Li-ion Battery AnodeCen, Yinjie 20 January 2017 (has links)
The demand for high performance Lithium-ion batteries (LIBs) is increasing due to widespread use of portable devices and electric vehicles. Silicon (Si) is one of the most attractive candidate anode materials for the next generation LIBs because of its high theoretical capacity (3,578 mAh/g) and low operation potential (~0.4 V vs Li+/Li). However, the high volume change (>300%) during Lithium ion insertion/extraction leads to poor cycle life. The goal of this work is to improve the electrochemical performance of Si/C composite anode in LIBs. Two strategies have been employed: to explore spatial arrangement in micro-sized Si and to use Si/graphene nanocomposites. A unique branched microsized Si with carbon coating was made and demonstrated promising electrochemical performance with a high active material loading ratio of 2 mg/cm2, large initial discharge capacity of 3,153 mAh/g and good capacity retention of 1,133 mAh/g at the 100th cycle at 1/4C current rate. Exploring the spatial structure of microsized Si with its advantages of low cost, easy dispersion, and immediate compatibility with the prevailing electrode manufacturing technology, may indicate a practical approach for high energy density, large-scale Si anode manufacturing. For Si/Graphene nanocomposites, the impact of particle size, surface treatment and graphene quality were investigated. It was found that the electrochemical performance of Si/Graphene anode was improved by surface treatment and use of graphene with large surface area and high defect density. The 100 nm Si/Graphene nanocomposites presented the initial capacity of 2,737 mAh/g and good cycling performance with a capacity of 1,563 mAh/g after 100 cycles at 1/2C current rate. The findings provided helpful insights for design of different types of graphene nanocomposite anodes.
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Hydrometallurgically generated nanostructured lead (II) oxide from depleted lead-acid batteries for potential reuse in next generation electrochemical systemsLiu, Robert Chi Yung January 2017 (has links)
The recycling of lead-acid batteries (LABs) is currently an energy intensive, inefficient and polluting procedure. An alternative hydrometallurgical recycling process is investigated in this study. PbO, PbO2, and PbSO4 were individually reacted with a mixture of aqueous citric acid and sodium hydroxide solution, with hydrogen peroxide being used as a reducing agent for PbO2. Pure lead citrate of either Pb(C6H6O7)·H2O or Pb3(C6H5O7)2·3H2O was the product crystallized in each leaching experiment depending on the initial conditions. Combined spent electroactive paste materials from industry were leached and processed. 2.5 M H2O2, 3.2 M C6H8O7·H2O and 3.5 M NaOH were used for optimal leaching and were successful in synthesising Pb3(C6H5O7)2·3H2O after less than one hour. These amounts could be reduced by individual leaching of plate materials. The combustion-calcination of Pb3(C6H5O7)2·3H2O was successful in generating PbO containing both forms of the polymorph α and β crystal phases together with metallic Pb. A novel method to generate PbO from lead citrate was found through a self-sustaining combustion route where leached waste materials were preheated to 270 °C for ~15 minutes and were found to self-sustain a smouldering reaction to produce PbO with a predominately β phase containing metallic Pb. Electrochemical analysis of PbO from Pb3(C6H5O7)2·3H2O demonstrated the viability in the by-product to be used in an electroactive paste and therefore reused in new LABs. Pure α-PbO was generated from both forms of lead citrate, Pb(C6H6O7)·H2O and Pb3(C6H5O7)2·3H2O using NaOH. Pure β-PbO was also generated from Pb(C6H6O7)·H2O and Pb3(C6H5O7)2·3H2O using NaOH through dissolution/re-precipitation reactions. PbCO3 was successfully generated from Pb(C6H6O7)·H2O and Pb3(C6H5O7)2·3H2O using NaOH, NaHCO3 and an acid in a series of disassociation and re-precipitation reactions. PbCO3 could be used to thermally generate α and β-PbO as well as Pb3O4 by calcination at 350, 600 and 450 °C respectively. Glycerol was entrained in both PbCO3 and α-PbO as an in-situ reducing agent to generate PbO containing metallic Pb. Acid reactivity and absorption characteristics of PbO derived from Pb3(C6H5O7)2·3H2O heated in CO2 were equal to and greater than those used in industry for both automotive and industrial batteries.
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Collaboration in family violence intervention: A process evaluation of the hamilton Family Safety TeamGregg, Lisa January 2007 (has links)
The Family Safety Team (FST) is a collaborative intervention developed to address family violence in New Zealand. Interagency collaborations are effective at addressing the social supports for battery, improving the systems and responses of agencies that address battery, and improving cohesion and consistency across agencies. The FST has a particular focus on justice system agencies. The purpose of this research was to evaluate the Hamilton FST. The research was conducted using in-depth interviews with FST members and others directly involved with the project, archival research using police family violence files, observation of FST meetings, and a focus group with battered women. The evaluation was constructed around four aims: to identify any barriers to establishing the FST, to assess the strengths and weaknesses of the Hamilton FST, to determine the adequacy of the FST structure, and to assess the extent to which the FST has improved the ability of agencies to enhance the safety and autonomy of battered women and hold offenders accountable. An overall finding of this evaluation was that people are feeling very positive about the Hamilton FST. The evaluation found that the FST has increased contact and communication between community and government agencies, and there was improvement in each agency's awareness of the policies, processes and protocols of other agencies in the FST. The evaluation found some limitations in the amount of monitoring and measurable outcomes from the FST, but this was understandable considering the infancy of the project and the time taken for members to understand their roles and the function of the FST. However, there were some positive developments in police responsiveness: an improved police attitude towards family violence cases, and an increase in cases coded as family violence. An important finding of this evaluation was that the Hamilton FST is functioning as a genuine collaboration. This seemed to be due to: mutual respect and an equal distribution of power among FST members, trusted working relationships, recognising each member for their area of expertise, and the role of the coordinator. There are, however, some limitations of the FST model that FST members need to acknowledge.
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Modeling of Transport in Lithium Ion Battery ElectrodesMartin, Michael 2012 May 1900 (has links)
Lithium ion battery systems are promising solutions to current energy storage needs due to their high operating voltage and capacity. Numerous efforts have been conducted to model these systems in order to aid the design process and avoid expensive and time consuming prototypical experiments. Of the numerous processes occurring in these systems, solid state transport in particular has drawn a large amount of attention from the research community, as it tends to be one of the rate limiting steps in lithium ion battery performance. Recent studies have additionally indicated that purposeful design of battery electrodes using 3D microstructures offers new freedoms in design, better use of available cell area, and increased battery performance.
The following study is meant to serve as a first principles investigation into the behaviors of 3D electrode architectures by monitoring concentration and cycle behaviors under realistic operating conditions. This was accomplished using computational tools to model the solid state diffusion behavior in several generated electrode morphologies. Developed computational codes were used to generate targeted structures under prescribed conditions of particle shape, size, and overall morphology. The diffusion processes in these morphologies were simulated under conditions prescribed from literature.
Primary results indicate that parameters usually employed to describe electrode geometry, such as volume to surface area ratio, cannot be solely relied upon to predict or characterize performance. Additionally, the interaction between particle shapes implies some design aspects that may be exploited to improve morphology behavior. Of major importance is the degree of particle isolation and overlap in 3D architectures, as these govern gradient development and lithium depletion within the electrode structures. The results of this study indicate that there are optimum levels of these parameters, and so purposeful design must make use of these behaviors.
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Energy use analysis and technology for electric transit busesHinse, Pierre R. 01 May 2010 (has links)
Electric vehicles offer a method of transportation where the energy generation process is moved from the on-board engine to the electrical generation system. The Canadian electrical generation mix has a significant portion of low carbon and renewable sources. This low environmental impact source of energy is then transferred to electric vehicles when they are charged from the grid. This thesis analyses the energy flow for such electric vehicles, particularly buses. Battery systems and charger technology, core to the vehicle operations, are examined; looking at energy flow from plug to wheels. Field data collected from on-board recordings and simultaneous Global Positioning System (GPS) signals were used to develop a new predictive model for an electric bus. The mathematical model for the electric bus was then compared with a similar sized diesel engine vehicle model using the Powertrain System Analysis Toolkit (PSAT). The operational energy cost of the electric bus is contrasted with a similarly sized Compression Ignition (CI) engine bus and was found to be very favourable. Also cost effective battery system upgrades to the present system were analysed for improved return on investment. / UOIT
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Polymer Electrolytes for Rechargeable Lithium/Sulfur BatteriesZhao, Yan January 2013 (has links)
With the rapid development of portable electronics, hybrid-electric and electric cars, there is great interest in utilization of sulfur as cathodes for rechargeable lithium batteries. Lithium/sulfur batteries implement inexpensive, the earth-abundant elements at the cathode while offering up to a five-fold increase in energy density compared with the present Li-ion batteries. However, electrically insulating character of sulfur and solubility of intermediate polysulfides in organic liquid electrolytes, which causes rapid capacity loss upon repeated cycling, restrict the practical application of Li/S batteries.
In this thesis, the gel polymer and solid polymer electrolytes were synthesized and applied in Li/S batteries. A gel polymer electrolyte (GPE) was formed by trapping 1 M lithium bistrifluoromethane-sulfonamide (LiTFSI) in tetraethylene glycol dimethyl ether (TEGDME) electrolyte in a poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) /poly(methylmethacrylate) (PMMA) polymer matrix. The electrochemical properties of the resulting GPE were investigated in lithium/sulfur battery. The gel polymer battery exhibited a high specific capacity of 753.8 mAh gˉ¹ at the initial cycle, stable reversible cycling and a capacity retention about 80% over 40 cycles along with a high Coulombic efficiency. Comparative studies conducted with the 1 M LiTFSI liquid electrolyte cell demonstrated that a cell with liquid electrolyte has remarkably low capacity retention and Coulombic efficiency compared with the GPE cell. In the further studies, a solid polymer electrolyte (SPE) based on poly- (ethylene-oxide)/nanoclay composite was prepared and used to assemble an all-solid-state lithium/sulfur battery. The ionic conductivity of the optimized electrolyte has achieved about 3.22×10ˉ¹ mS cmˉ¹ at 60 °C. The Li/S cell with this SPE delivered an initial discharge capacity of 998 mAh gˉ¹ when operated at 60 °C, and retained a reversible capacity of 634 mAh gˉ¹ after 100 cycles. These studies has revealed that the electrochemical performance of lithium/sulfur cells, including charge-discharge cyclability and Coulombic efficiency, can be significantly improved by replacing liquid electrolytes with solid polymer and gel polymer electrolytes, which reduce the polysulfide shuttle effect and could protect the lithium anode from the deposition of the electrochemical reaction, leading to higher sulfur utilization in the cell.
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Nanostructured Cathodes : A step on the path towards a fully interdigitated 3-D microbatteryRehnlund, David January 2011 (has links)
The Li-ion field of battery research has in the latest decades made substantial progress and is seen to be the most promising battery technology due to the high volume and specific energy densities of Li-ion batteries. However, in order to achieve a battery capable of competing with the energy density of a combustion engine, further research into new electrode materials is required. As the cathode materials are the limiting factor in terms of capacity, this is the main area in need of further research. The introduction of 3-D electrodes brought new hope as the ion transportpath is decreased as well as an increased electrode area leading to an increased capacity. This thesis work has focused on the development of aluminium 3-D current collectors in order to improve the electrode area and shorten the Li-ion transportpath. By using a template assisted electrodeposition technique, nanorods of controlled magnitude and order can be synthesized. Furthermore, the electrodeposition brings excellent possibilities of upscaling for future industrial manufacturing of the batterycells. A polycarbonate template material which showed interesting properties,was used in the electrodeposition of aluminium nanorods. As the template pores were nonhomogeneously ordered a number of nonordered nanorods were expected to arise during the deposition. However, a surplus of nanorods in reference to the template pores was acquired. This behavior was investigated and a hypothesis was formed as to the mechanism of the nanorod formation. In order to achieve acomplete cathode electrode, a coating of an ion host material on the nanorods isneeded. Due to its high capacity and voltage, vanadium oxide was selected. Based on previous work with electrodeposition of V2O5 on platinum, a series of experiments were performed to mimic the deposition on an aluminium sample. Unfortunately, the deposition was unsuccessful as the experimental conditions resulted in aluminium corrosion which in turn made deposition of the cathode material impossible. The pH dependence of the deposition was evaluated and the conclusion was drawn, that electrodeposition of vanadium oxide on aluminium is not possible using this approach.
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Bidirectional Charge Equalization Circuit for Series-Connected BatteriesOu, Wen-Yi 19 July 2005 (has links)
A bidirectional charge equalization circuit based on a bidirectional flyback converter topology is proposed to achieve the balance charging and discharging in series-connected battery bank. The circuit comprises a multi-input transformer, in which the batteries bank are connected to the primary windings via associated active power switches. During discharging, the batteries transfer energy to the load by activating the primary power switches. On the contrary, the batteries are charged by activating the secondary power switch in which the load is replaced by a power source.
In order to simplify the control circuit and provide a flexible modulation, a digital signal processor (DSP) with the associated sensors and interface circuits are used as the control kernel. It is used to monitor the variations of battery voltages, and to regulate the duty ratio of the converter to provide a balance charging or discharging among the batteries.
A battery bank with four series connected lead-acid batteries is used for illustrating the operation of the bidirectional charge equalization circuit. The experimental results advocate the applicability of the proposed approach.
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Investigation on Operating Characteristics of Individual Cell among Battery PackChen, Wen-Chih 04 July 2006 (has links)
Due to the discrepancy among series-connected cells in a lead-acid battery pack, the restored capacities may not be the same during the charging/discharging processes. Through repeated charging and discharging, one can find that the unbalance of individual series-connected battery cell of lead-acid battery is getting worse, because those cells of poor state of charge may have negative voltage, causing reverse charging from the other cells. This abnormal operation results in not only more energy consumption, but also the acceleration of the battery-cell aging and the remarkable reduction of its lifetime.
For the purpose of investigating this problem, the operating characteristics of each cell is under study. The battery cells are purposely charged by different floating voltages and discharged by different cutoff voltages. The investigation results show that the lifecycles of battery cells are affected more significantly by floating charging voltage than by the discharging cutoff voltage. It is also found that a long time reverse charging has a destructive effect on the battery cells.
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