Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 112-113). Also available via the Internet.

Thesis (M.Sc.)--City University of Hong Kong, 2004. / At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 165 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 163-165).

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 120-121). Also available via the Internet.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Julian, Alexander L. Second Reader: Crisiti, Roberto. "December 2009." Description based on title screen as viewed on January 28, 2010. Author(s) subject terms: Pulsed power, charger, buck converter, field programmable gate array (FPGA), lithium-ion batteries. Includes bibliographical references (p. 77-79). Also available in print.

This work develops a methodology to facilitate the optimum design of spacecraft power processing systems. Emphasis is placed on the battery charge and discharge systems. A comparison of several battery charge and discharge topologies is presented. Characteristics which effect the overall system performance are addressed including size, weight, efficiency, dynamic performance, electromagnetic interference, and reliability. A detailed comparison, using nonlinear design optimization techniques, is performed for three candidate topologies for application to the NASA Earth Observing System (EOS) satellite battery discharger. Experimental verification is provided. A novel zero-voltage-switching (ZVS) bidirectional converter topology is presented. A bidirectional battery charger / discharger has several advantages, including a potentially substantial system weight savings. However, it is shown that most of the advantages can not be realized unless zero-voltage-switching is incorporated. The design of a novel ZVS, multi-module, multi-phase, bidirectional converter with application to the NASA EOS satellite battery charger / discharger system is presented. The system not only yields high efficiency and light weight, but also possesses superior dynamic characteristics when compared to either a conventional bidirectional converter or separate charge and discharge converters. Design considerations for system control of the NASA EOS satellite are presented. A methodology is presented to insure system stability with an unknown complex load. / Ph. D.

The design, analysis, and testing of a multi-module, multi-phase (MMMP) battery charger for the NASA Earth Observing System (EOS) is presented. The MMMP converter is comprised of four independent buck converters switched 90° out of phase. The MMMP charger is compared to a single module battery charger, and shown to provide significant performance improvements. The power stage is designed for maximum efficiency and minimum weight. The control loops (Charge Regulation and Bus Voltage Regulation) designs are presented and the small-signal models are verified with experimental results. The charger testing is facilitated by the use of the Space Platform Power System Hardware Testbed. The testbed utilizes battery and solar array simulators which allow for realistic battery charger testing. / Master of Science

Decarbonization of the marine transportation sector is contributing to the growth of electric recreational boats. The growth of electric recreational boats also means an increase in charging demand to meet the power needs of electric boats to address the problem of range anxiety. To meet the charging demand of electric boat owners, electrification of existing public boat marinas is necessary. The objective of this study is to determine the optimal number of fast and slow chargers to meet charging demand of electric boats at public boat marinas. This study proposes a mathematical model formulated using mixed integer linear optimization programming (MILP). The model is validated using 9 public marinas owned by the city of Stockholm; the technical and economic data of one of the existing electric boats in the Swedish market, electric chargers; and hourly availability profile of boats at the marinas considered. The economic analysis was carried out to determine the year each station will break-even financially. The result obtained is the number of slow chargers and fast chargers to meet the charging demand of all electric boats; and the power drawn per charger type per station. Due to availability profile and charging demand of the boats, the model optimized for higher number of fast chargers compared to slow chargers at some of the stations; and at some of the stations, higher number of slow chargers compared to fast chargers; and equal number of slow and fast chargers at some of the stations. Also, maximum power is drawn between 01:00 and 03:00 at midnight and between 13:00 and 15:00 during the day, and this was as a result of the lowest average electricity price within this time period. In addition, the economic analysis shows that all the stations are financially viable and break-even within the first seven years of their lifetime. The result obtained shows that the number of electric chargers (slow and fast) generated by the model meet the charging demands of all the boats at each of the stations optimally. / Avkarbonisering av sjötransportsektorn bidrar till tillväxten av elektriska fritidsbåtar. Tillväxten av elektriska fritidsbåtar innebär också en ökning av laddningsefterfrågan för att möta elbåtarnas kraftbehov för att lösa problemet med räckviddsångest. För att möta laddbehovet från elbåtsägare är elektrifiering av befintliga offentliga båthamnar nödvändig. Syftet med denna studie är att fastställa det optimala antalet snabba och långsamma laddare för att möta laddningsbehovet för elbåtar vid offentliga båthamnar. Denna studie föreslår en matematisk modell formulerad med hjälp av blandad heltals linjär optimeringsprogrammering (MILP). Modellen är validerad med 9 offentliga småbåtshamnar som ägs av Stockholms stad; tekniska och ekonomiska data för en av de befintliga elbåtarna på den svenska marknaden, elektriska laddare; och timvis tillgänglighetsprofil för båtar vid de övervägda marinorna. Den ekonomiska analysen genomfördes för att fastställa vilket år varje station kommer att nå ekonomiskt nollresultat. Resultatet som erhålls är antalet långsamma laddare och snabbladdare för att möta laddningsbehovet för alla elektriska båtar; och ström som dras per laddartyp per station. På grund av båtarnas tillgänglighetsprofil och laddningsbehov, optimerade modellen för fler snabbladdare jämfört med långsamma laddare på några av stationerna; och på några av stationerna, högre antal långsamma laddare jämfört med snabbladdare; och lika många långsamma och snabba laddare på några av stationerna. Dessutom dras maximal effekt mellan 01:00 och 03:00 vid midnatt och mellan 13:00 och 15:00 under dagen, och detta var ett resultat av det lägsta genomsnittliga elpriset inom denna tidsperiod. Dessutom visar den ekonomiska analysen att alla stationer är ekonomiskt bärkraftiga och nollresultat inom de första sju åren av sin livstid. Resultatet som erhållits visar att antalet elektriska laddare (långsamma och snabba) som genereras av modellen uppfyller laddningskraven för alla båtar vid var och en av stationerna.

Bidirectional onboard chargers (OBCs) are becoming mainstream commercial charging equipment for electric vehicles (EVs) because of their compactness, flexibility, and demand-response capabilities for power backup. This thesis focuses on the novel phase shift (PS) modulation techniques for efficiency improvement for bidirectional OBCs, including two-stage onboard chargers (TSOBCs) and single-stage onboard chargers (SSOBCs). A comprehensive overview and investigation of the state-of-the-art solutions of bidirectional OBCs are presented. It reviews the current industrial status, industrial applications, and future trends and challenges. A detailed overview of the promising topologies for bidirectional OBCs, including two-stage and single-stage structures, is also discussed in this thesis. Traditional PS modulation has been widely used in the back-end DC/DC converters of the TSOBCs because of its simple implementation. However, it is challenging to keep high efficiency at boundary operating points within wide specifications. Therefore, to improve efficiency at the boundary point for TSOBCs, the hybrid multiple phase shift (HMPS) modulation technique with minimal peak current optimization is presented to maximize the zero-voltage switching (ZVS) range. Compared to traditional single phase shift (SPS) modulation, the experimental results verify that the presented HMPS modulation strategy provides 1%-2% higher efficiency at the boundary points. On the other hand, an improved compact SSOBC topology and novel PS modulation techniques are proposed. Since the traditional PS modulation is challenging for AC/DC converters to keep a unity power factor (PF), novel PS modulation techniques are presented for the proposed SSOBC. Firstly, a sinusoidal single phase shift (SSPS) modulation introduces a sinusoidal phase shift to maintain a high PF and high efficiency within a wide operating point. However, due to the high current at the zero-crossing point of the grid voltage of the SSPS modulation, the novel adaptive sinusoidal single phase shift (ASSPS) modulation is presented to address this issue, which reduces conduction loss and increases efficiency. Secondly, based on the ASSPS modulation, the adaptive sinusoidal extended phase shift (ASEPS) modulation with minimal peak current optimization is presented to introduce one more degree of freedom to extend the ZVS flexibility, which reduces switching loss. Moreover, the minimal peak current optimization reduces transformer current, further decreasing conduction losses. Therefore, the power loss is minimized. Finally, this thesis presents the general design guideline of a 6 kW Silicon Carbide (SiC)-based bidirectional SSOBC, contributing to the further development of bidirectional SSOBC application. Experimental results verify the operating principle and high PF of the proposed SSPS, ASSPS, and ASEPS modulation. 1 kW experimental testing has validated that the peak efficiency is 95.3% with ASSPS modulation and 95.9% with ASEPS modulation. Compared to the existing pulse width modulation (PWM), the ASSPS modulation increased efficiency by 1.1%, and ASEPS modulation further increased by 1.7%. / Thesis / Doctor of Philosophy (PhD)

A vehicular battery must consist of a large number of cells to provide the necessary energy and power. Management only at the level of the battery pack causes out-of-investigation cells and lack of cell equalization ability. Therefore, in the smart module concept, cells are first grouped into modules, which are then connected to the battery pack. Each module is an independent unit with a controller to investigate and control cells. Based on this concept, the work in this thesis redistributes tasks among module controllers and a central controller, applies a self-power design to enhance module independence, and selects the newly developed automotive ICs and sensors. Finally, a prototype of the BMS has been developed and successfully applied in a series of HEVs. / Cell equalization is a crucial technique to balance the cells inside a battery pack, with the ability to maximize pack capacity and protect cells from damage. For the bi-directional Cuk equalizing circuit, we propose a SoC based, instead of voltage based, fuzzy controller to intelligently determine the equalizing current, with the aim of reducing equalizing duration, enhancing equalizing efficiency, and protecting cells. The inputs to the controller are specially designed as the difference in SoC, the average SoC, and the total internal resistance. Because of the lack of theoretical analysis on equalizing current in the electrochemistry field, we utilize a fuzzy controller to incorporate the experience and knowledge of experts. Simulations and experiments verify its availability and efficacy. Especially for a LiFePO4 battery, a large SoC difference may lead to only a small difference in voltage and cause the failure of a traditional voltage based equalizer. The SoC based method successfully avoids this problem and obtains good performance in equalizing LiFePO4 cells. / Fast charge is intended to charge a battery as fast as possible, without any damage and with high energy efficiency, thus helping to reduce vehicle out-of-service time and promote the commercialization of EVs. Battery safety and charging efficiency are partially reflected by the increase in temperature during the charging process. Therefore, the aims of this thesis were to accelerate charging speed and reduce the temperature increase. We introduce a model predictive control framework to control the charging process. An RC model and the modified enhanced self-correcting model are employed to predict the future SoC in simulations and experiments respectively. A single-node lumped-parameter thermal model and a neural network trained by real experimental data are also applied respectively. In addition, a genetic algorithm is applied to optimize the charging current under multiple objectives and constraints. Simulation and experimental results strongly demonstrate that the Pareto front of the proposed algorithm dominates that of the popular constant current constant voltage charge method. / State of charge (SoC) is a battery state indicating its residual capacity. It is the fundamental state of the battery and is the basis for other battery operations. However, SoC is not a directly measurable state and has to be obtained by estimation techniques. Aiming to enhance the anti-noise ability of SoC estimation in a real vehicle environment, we propose a SoC estimation framework consisting of an adaptive nonlinear diffusion filter to reduce the noise of current measurement, a self-learning mechanism to remove its zero-drift, an open loop coulomb counting estimator and a model based closed loop filter to estimate SoC, and a data fusion unit to reach the final estimation result. In a simulation study, the closed loop filter is implemented based on an RC model and Hinfinity filter. In experiments and application, we modify the enhanced self-correcting model to model a type of LiFePO4 battery and apply an extended Kalman filter to estimate SoC. The framework has been demonstrated to improve accuracy and anti-noise ability, and achieves the technique upgrading goal recently published by the Chinese government. / The automotive industry has experienced a significant boom in recent years, accelerating the problems of energy shortage and environmental disruption around the world. To solve the two problems, electric vehicles (EVs), including battery electric vehicles (BEV), hybrid electric vehicles (HEV), and fuel-cell electric vehicles (FEV), have been proposed and studied in recent years. Despite the efforts devoted to the development of EVs by both the scientific research and industrial communities, there are still many obstacles hindering the mass commercialization of EVs. Among these obstacles, the battery system, the new energy storage component in EVs, is one of the most important yet most difficult parts of EV design, and the battery management system (BMS) is recognized as the single most important technical issue in the successful commercialization of EVs. / Yan Jingyu. / Adviser: Xu Yangsheng. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 166-182). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.