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D. Phil. (Energy Studies) / Quantifying energy consumed and emissions produced by transport is essential for effective policy formulation and urban environmental management. Current first-world methods for determining vehicle emissions factors are technology and resource intensive, and results cannot be applied directly to cities in other parts of the world. There is a need for alternative cost-effective and accurate methods for determining real-world fuel consumption and emissions from vehicles in cities of the developing world. In this thesis, a new emissions simulation and inventory model is developed and implemented as a software tool. A novel application of low cost on-board diagnostics equipment and Global Positioning System sensors is devised to survey engine-operating parameters, driving conditions and vehicle usage profiles needed by the model. An emissions inventory is produced for the City of Johannesburg using the software tool and surveying method to demonstrate the overall process. The core contribution of this thesis is the logical development of data structures and software tools which link base engine-operating patterns (of engine speed and engine load), derived from the literature, to measured engine-operating patterns and vehicle activity from real-world driving. A range of real-world driving cycles and emission factors published by the Swiss Institute of Materials Science and Technology are transformed to produce the base engine-operating patterns and their corresponding emissions factors. The calculation of emission factors for real-world driving involves matching measured engineoperating patterns to combinations of the base engine-operating patterns using numerical methods. The method is validated using a cross validation technique. The emissions inventory application integrates measured engine-operating patterns, vehicle activity, fleet structure, fuel sales and the emissions simulation procedure to calculate total emissions. Fuel consumption and emissions of interest are CO2, CO, HC, NOx. Measurements of engine operating parameters and vehicle usage patterns were recorded for 30 privately owned passenger vehicles from the Johannesburg fleet. The selection included Euro-0 (a mixture of pre Euro-1 vehicles), Euro-2 and Euro-3 petrol vehicles, and Euro-2 diesel private passenger vehicles. Fifteen billion vehicle kilometres were driven in Johannesburg by private passenger vehicles per year consuming 325 million litres of diesel and 1 524 billion litres of petrol. iv Total emissions were estimated to be 4.13 Mt CO2, 82.77 kt CO, 9.15 kt HC, and 24.49 kt NOx. Between 88 and 93% of the total emissions were from vehicles which fall into the Euro-0 petrol category. Diesel vehicles did not make a significant contribution to CO and HC emissions but contributed 14% of the NOx and 19% of the CO2 emissions. During weekdays, 28 to 31% and 25 to 27% of the total fuel consumption and emissions were due to the morning commute and the evening commute periods respectively. Although minibus taxis, buses, freight and vehicle age significantly impact on total fuel consumption and emissions in cities they were not considered within the scope of this study. Vehicle usage patterns are analysed to produce spatial maps and diurnal charts of congestion on suburban roads, streets and highways within the Johannesburg municipal area. Times and locations of congestion are presented in terms of a standard congestion index, and suggestion given on how and where congestion problems could be addressed. This study shows that vehicle emissions inventories can be cost effectively produced by surveying engine-operating parameters and vehicle usage profiles using on-board diagnostics and Global Positioning System sensors and simulating emissions factors using a new emissions simulation and emissions inventory model.

America’s energy crunch— something new for a country that has been used to great affluence. America’s smog— an eye stinging, lung burning situation which the Environmental Protection Agency has "promised" to rectify. These are two outstanding problems that face the engineer and scientist of today. The end of the era of cheap gasoline has brought the beginnings of a quiet revolution to Detroit: an improvement in the efficiency, economy and emission level of the American automobile. Word has penetrated to the automotive engineers that the emissions level, fuel economy and automobile safety are the prime design considerations for the automobile of the future.

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.

Indiana University-Purdue University Indianapolis (IUPUI) / Plug-in Hybrid Electric Vehicles (PHEV) are new generation Hybrid Electric Vehicles (HEV) with larger battery capacity compared to Hybrid Electric Vehicles. They can store electrical energy from a domestic power supply and can drive the vehicle alone in Electric Vehicle (EV) mode. According to the U.S. Department of Transportation 80 % of the American driving public on average drives under 50 miles per day. A PHEV vehicle that can drive up to 50 miles by making maximum use of cheaper electrical energy from a domestic supply can significantly reduce the conventional fuel consumption. This may also help in improving the environment as PHEVs emit less harmful gases. However, the Energy Management System (EMS) of PHEVs would have to be very different from existing EMSs of HEVs. In this thesis, three different Energy Management Systems have been designed specifically for PHEVs using simulated study. For most of the EMS development mathematical vehicle models for powersplit drivetrain configuration are built and later on the results are tested on advanced vehicle modeling tools like ADVISOR or PSAT. The main objective of the study is to design EMSs to reduce fuel consumption by the vehicle. These EMSs are compared with existing EMSs which show overall improvement. x In this thesis the final EMS is designed in three intermediate steps. First, a simple rule based EMS was designed to improve the fuel economy for parametric study. Second, an optimized EMS was designed with the main objective to improve fuel economy of the vehicle. Here Particle Swarm Optimization (PSO) technique is used to obtain the optimum parameter values. This EMS has provided optimum parameters which result in optimum blended mode operation of the vehicle. Finally, to obtain optimum charge depletion and charge sustaining mode operation of the vehicle an advanced PSO EMS is designed which provides optimal results for the vehicle to operate in charge depletion and charge sustaining modes. Furthermore, to implement the developed advanced PSO EMS in real-time a possible real time implementation technique is designed using neural networks. This neural network implementation provides sub-optimal results as compared to advanced PSO EMS results but it can be implemented in real time in a vehicle. These EMSs can be used to obtain optimal results for the vehicle driving conditions such that fuel economy is improved. Moreover, the optimal designed EMS can also be implemented in real-time using the neural network procedure described.

M.S.

In the traffic engineering field today, much attention is being given to the area of intersection control. The intersection has long been recognized as the most critical element in our highway system. Accidents, delay, wasted fuel and congestion are greatest at intersections. The variable having the greatest effect on traffic flow at an intersection or in a network of intersections is the traffic signal timing. In recent years, several computer programs have been developed to aid the traffic engineer in signal timing. This thesis examines the effect of the signal timing plans generated by one of the more widely used programs, TRANSYT 7, on the energy consumption of two signalized networks. Also examined are the relationships of delay and stops to fuel consumption. The TRANSYT 7 program was used to generate signal timing plans over a range of cycle lengths and stop penalties. The TRANSYT 7 signal timing plans were entered into NETSIM, a microscopic traffic simulation program, to determine their effect on fuel consumption in the two study networks. / Master of Science

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Thesis (Elec.E)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Wing Hong Lee. / Elec.E

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