Thesis (M.E. Mechanical Engineering)--University of Waikato, 2008. / Title from PDF cover (viewed October 1, 2008) Includes bibliographical references (p. 122-130)

The electric vehicles, as the most promising solution for achieving high fuel economy, have significantly better emission profile than conventional vehicles powered by fossil fuels. However, range anxiety and the limited accessible fast-charging infrastructures mainly restrain the drivers from adopting the electric vehicles that have much higher energy efficiency. Due to the internal and external factors, the cells in the battery pack degrade differently, leading to a usable capacity that is less than the available capacity if they are left unbalanced, which ultimately shortens the driving range. Therefore, an external circuitry, i.e. battery balancing circuit, that manages the unbalanced cells is installed to maximize the usable capacity, and thus, to prolong the driving range. However, the most commonly adopted balancing circuit is the dissipative balancing strategy in the large-scale electric vehicle productions, where the available capacity is underutilized. One of the most efficient redistributive balancing strategies that overcome the drawbacks of the dissipative one is converter-based strategy that monitors and regulates each paralleled-connected cell module. Nevertheless, installing the individual DC-DC converters on each module is not cost-friendly, and thus, reducing the cost of the converter-based balancing system becomes the priority for large adoptions of the redistributive balancing systems in electric vehicles. This thesis proposes a dual-cell link that integrates the functionalities of the auxiliary power module, battery gauging and battery balancing, leading to a low-cost solution comparable with the dissipative balancing. The topological improvements are made achieving 50% less number of the needed converters compared with the existing topologies. In addition, the integration and minimization are the design targets in terms of the main circuit components. The costly components, such as MOSFETs and magnetic components, are curtailed by 62.5%-75% and 50%-100%, respectively, with no sacrifices on the balancing speed. In order to achieve the magnetic integration, the detailed circuit model is developed using average- and small-signal modeling techniques. The design procedure for the half-full bridge converter with the cored transformer is firstly discussed, followed by a further minimized dual-half active bridge converter with a coreless transformer. Following the design procedure, two systems are characterized, built, tested and validated with the real batteries. Not only is the cost reduced, but also the balancing process is facilitated, which is realized by an additional balancing path. A DC current offset between the adjoining cells in one link can be introduced to the circuit by utilizing a normally undesired volt-amp imbalance in the transformer, which provides the extra cell-to-cell balancing path. An asymmetric duty cycle control is proposed to regulate the DC current offset so that the different balancing modes can be achieved. With the enabled cell-to-cell path, the balancing speed can be reduced by 50% compared with the conventional cell-to-stack only balancing methods with a state-of-charge difference of 20% between two adjoining cells. The auxiliary power module requires the proposed converters to work as efficiently as possible within its wide operating range. However, the efficiency of the half-bridge systems drops at light-load conditions due to the loss of the soft-switching capability and high conduction loss. In order to overcome this drawback, the variable frequency modulation is normally preferred. A conduction-loss based control criteria is proposed, inheriting the benefits of the conventional variable frequency modulation while maintaining the optimized conduction loss. It is validated on the converter prototype that the proposed control criteria can achieve 1-2% better efficiency with an extremely simple but robust control logic compared with the critical soft switching.

Exhaust emissions from vehicles are major contributor to local air pollution and global climate change. Electric vehicles are zero tailpipe emission, while electricity can be generated from renewable sources. They are widely considered by policymakers. Although the Hong Kong Government carried out various policies in last few years, the market share of electric vehicles is still low, particularly in the public transport sector. This dissertation aims to investigate the policy drivers and obstacles to electric vehicles adoption in Hong Kong, focus on public transport vehicles – buses, public light buses and taxis, because they are the largest contributor to the street-level air pollution. The methodologies of this study included two parts. The first part is an extensive literature review and overseas case studies. The second part is survey interviews on 34 decision makers from public transport operators, public vehicle associations, infrastructure developers, car park management companies and property management companies. The survey covered 25.2 percent of total licensed public vehicles in Hong Kong in March 2013. The investigation reveals that long payback period, lack of infrastructure support, battery capacity, and range anxiety are the key obstacles to public electric vehicles adoption in Hong Kong, while environmental concern is less important to the stakeholders. As breakthroughs in technology will compensate most of the shortcomings, in short-term, provide direct subsidy on a non-linear sliding scale, and allocate land for overnight charging are vital for the Government to push public electric vehicles adoption. In medium to long-term, the Government has to be more proactive and roll out a clear roadmap for future development. Provide governmental research and development support, release the threshold of Green Pilot Transport Fund, further amendment on Road Traffic (Expressway) Regulations (Cap. 374Q), enhance collaboration with electric vehicle manufacturers, increase promotion, public education and professional training are recommended. The dissertation ends with a future research agenda. Suggestions included investigates the effectiveness of public electric vehicles' operation and acceptance by passengers; monitoring public electric vehicles' adoption, operation and development among Hong Kong and major regional competitors - Singapore and Shanghai. In addition, research on how China's expanding electric vehicle industry will influence public transport sector in the next two to three years' time. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / abstract / toc / Electrical and Electronic Engineering / Master / Master of Philosophy

Thesis (M.S.)--University of California, Davis, 2009. / Text document in PDF format. Title from PDF title page (viewed on November 4, 2009). "Received by ITS-Davis: April 2009"--Publication detail webpage. Includes bibliographical references (p. 113-122).

Thesis (M.S.)--Michigan State University. Electrical Engineering, 2008. / Title from PDF t.p. (viewed on Aug. 5, 2009) Includes bibliographical references (p. 230-231). Also issued in print.

Thesis (M.E.)--University of Canterbury, 2007. / Typescript (photocopy). "09 July 2007." Includes bibliographical references. Also available via the World Wide Web.

Thesis (M. Sc.)--University of Hong Kong, 1995. / Includes bibliographical references (leaf [110-114]).

This thesis (1) reports the development of simulation tools and control strategies for optimizing hybrid electric vehicle (HEV) energy management, and (2) reports the design and testing of a hydraulic hybrid school bus (HHB) prototype. A hybrid vehicle is one that combines two or more energy sources for use in vehicle propulsion. Hybrid electric vehicles have become popular in the consumer market due to their greatly improved fuel economy over conventional vehicles. The control strategy of an HEV has a paramount effect on its fuel economy performance. In this thesis, backward-looking and forward-looking simulations of three HEV architectures (parallel, power-split and 2-mode power-split) are developed. The Equivalent Cost Minimization Strategy (ECMS), which weights electrical power as an equivalent fuel usage, is then studied in great detail and improvements are suggested. Specifically, the robustness of an ECMS controller is improved by linking the equivalence factor to dynamic programming and then further tailoring its functional form. High-fidelity vehicle simulations over multiple drive-cycles are performed to measure the improved performance of the new ECMS controller, and to show its potential for online application. While HEVs are prominent in the consumer market and studied extensively in current literature, hydraulic hybrid vehicles (HHVs) only exist as heavy utility vehicle prototypes. The second half of this thesis reports design, construction, and testing of a hydraulic hybrid school bus prototype. Design considerations, simulation results, and preliminary testing results are reported, which indicate the strong potential for hydraulic hybrids to improve fuel economy in the school bus vehicle segment.

This paper is designed to assist communities with the successful introduction, integration and support of electric vehicles. It provides an introductory look at electric vehicle technology and its application within the community, and should act as a springboard for further investigation and plan development for interested communities. This paper outlines the basic history of electric vehicle technology, the recent forces which have prompted increased research and development, and the leading causes for this evolution in personal transportation. The core of the document describes the steps a community will need to take in order to successfully develop a local electric vehicle program. Initial steps include developing community goals, understanding the community and its transportation environment, and creating an organizational structure to successfully develop a local Electric Vehicle Action Plan. The organizational structure provided is divided into three basic elements; Policy, Infrastructure, and Public Awareness. The analysis of each element includes the identification and discussion of the critical issues, a description of the key participants who should be involved, and recommended methodology for initiating and supporting local electric vehicle commercialization. Furthermore, each element includes a short analysis of three separate market niches that are ripe for early electric vehicle introduction. These applications can be used by the community to develop a local electric vehicle demonstration program and establish a foundation on which to build an electric vehicle community. This paper, if used to its potential, can help communities develop a program which will successfully introduce and integrate electric vehicles into the local transportation mix and bring America a little closer to a sustainable transportation system. / Department of Urban Planning