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Technical Paper

Evaluation of Ethanol Blends for Plug-In Hybrid Vehicles Using Engine in the Loop

2012-04-16
2012-01-1280
Their easy availability, lower well-to-wheel emissions, and relative ease of use with existing engine technologies have made ethanol and ethanol-gasoline blends a viable alternative to gasoline for use in spark-ignition (SI) engines. The lower energy density of ethanol and ethanol-gasoline blends, however, results in higher volumetric fuel consumption compared with gasoline. Also, the higher latent heat of vaporization can result in cold-start issues with higher-level ethanol blends. On the other hand, a higher octane number, which indicates resistance to knock and potentially enables more optimal combustion phasing, results in better engine efficiency, especially at higher loads. This paper compares the fuel consumption and emissions of two ethanol blends (E50 and E85) with those for gasoline when used in conventional (non-hybrid) and power-split-type plug-in hybrid electric vehicles (PHEVs).
Journal Article

PHEV Energy Management Strategies at Cold Temperatures with Battery Temperature Rise and Engine Efficiency Improvement Considerations

2011-04-12
2011-01-0872
Limited battery power and poor engine efficiency at cold temperature results in low plug in hybrid vehicle (PHEV) fuel economy and high emissions. Quick rise of battery temperature is not only important to mitigate lithium plating and thus preserve battery life, but also to increase the battery power limits so as to fully achieve fuel economy savings expected from a PHEV. Likewise, it is also important to raise the engine temperature so as to improve engine efficiency (therefore vehicle fuel economy) and to reduce emissions. One method of increasing the temperature of either component is to maximize their usage at cold temperatures thus increasing cumulative heat generating losses. Since both components supply energy to meet road load demand, maximizing the usage of one component would necessarily mean low usage and slow temperature rise of the other component. Thus, a natural trade-off exists between battery and engine warm-up.
Book

Modern Electric, Hybrid Electric, and Fuel Cell Vehicles

2009-09-21
Air pollution, global warming, and the steady decrease in petroleum resources continue to stimulate interest in the development of safe, clean, and highly efficient transportation. Building on the foundation of the bestselling first edition, this second edition updates and expands its detailed coverage of the vehicle technologies that offer the most promising solutions to these issues affecting the automotive industry. Proven as a useful in-depth resource and comprehensive reference for modern automotive systems engineers, students, and researchers, this book speaks from the perspective of the overall drive train system and not just its individual components. New to the second edition: o A case study appendix that breaks down the Toyota Prius hybrid system o Corrections and updates of the material in the first edition o Three new chapters on drive train design methodology and control principles o A completely rewritten chapter on Fundamentals of Regenerative Braking
Technical Paper

Impact Study of Field-Weakening Operation of Electric Motors on Drive Train Oscillations

2002-03-04
2002-01-1089
Studying the dynamics of electric motor drives is not easy. Indeed, there is no unified approach to model both the mechanical and the electrical elements of the motor drive in order to bring an intuitive understanding of the dynamic behavior. Moreover, for traction purposes, the machines are often used at field-weakening operation, which can be a source of unwanted oscillations. In this paper, the gyrator-based equivalent circuit modeling is presented. The method allows the understanding of some aspects of the dynamic behavior of DC motor drives such as the interaction between electric inductances and the rotor inertia and their oscillating behavior.
Technical Paper

Study of Hybrid Electric Vehicle Drive Train Dynamics Using Gyrator-Based Equivalent Circuit Modeling

2002-03-04
2002-01-1083
The main idea in the concept of advanced vehicles is to combine two or more power plants in order to improve the overall efficiency of the vehicle. The modeling of advanced vehicle is challenging, mainly because of the presence of several power plants in the system. After a presentation of the generalized equivalent circuit theory, including the electrical analogy and the theory of generalized gyrators and transformers, the modeling technique is compared to existing methods. Then, vehicle subsystems are modeled from the mechanical drive train to the different power plants and energy storages, according to the methodology. Some typical hybrid architectures are processed through the modeling technique and a final equivalent circuit is presented and discussed for each of them. Finally, the study of electromechanical interactions and mechanical transients is presented.
Technical Paper

A Mild Hybrid Drive Train for 42 V Automotive Power System-Design, Control and Simulation

2002-03-04
2002-01-1082
In this paper, a mild hybrid drive train has been proposed. A small electric motor with low rated voltage (42 V) is used to (1) propel the vehicle at low speed, (2) replace the fluid-coupled torque converter and (3) realize regenerative braking. With proper design and control, the fuel economy in urban driving can be significantly improved without much change from conventional drive train to the mild hybrid drive train.
Technical Paper

Electronic Braking System of EV And HEV---Integration of Regenerative Braking, Automatic Braking Force Control and ABS

2001-08-20
2001-01-2478
The desirable braking system of a land vehicle is that it can stop the vehicle or reduce the vehicle speed as quickly as possible, maintain the vehicle direction stable and recover kinetic energy of the vehicle as much as possible. In this paper, an electronically controlled braking system for EV and HEV has been proposed, which integrates regenerative braking, automatic control of the braking forces of front and rear wheels and wheels antilock function together. When failure occurs in the electric system, the braking system can function as a conventional man-actuated braking system. Control strategies for controlling the braking forces on front and rear wheels, regenerative braking and mechanical braking forces have been developed. The braking energy that can be potentially recovered in typical driving cycle has been calculated. The antilock performance of the braking system has been simulated.
Technical Paper

42V Automotive Power Systems

2001-08-20
2001-01-2465
With the increase of hotel and ancillary loads and replacement of engine driven mechanical and hydraulic loads with electrical loads, automotive systems are becoming more electric. This is the concept of More Electric Cars (MEC) that necessitates a higher system voltage, such as the proposed 42V, for conventional cars. In this paper, the development of the 42V electric power system for vehicle applications is reviewed. The system architecture and motor drive problems associated with the 42V electric power system are analyzed. Solutions to these problems are also discussed.
Technical Paper

Systematic Design of Fuel Cell Powered Hybrid Vehicle Drive Train

2001-08-20
2001-01-2532
A general design methodology of the fuel cell powered hybrid vehicle drive train has been developed. With the methodology and a computer simulation program, all of the systematic parameters can be designed, such as, the rated power of the electric motor drive, fuel cell system, peaking power source as well as the energy capacity. An overall control strategy has also been developed. The main function of the control strategy is to properly control the power produced by the fuel cell system and the peaking power source, so as to meet the power demand, maintain the energy level of the peaking power source in its optimal region and operate the fuel cell system within its high efficiency region. In this paper, a design example has also been introduced in each section.
Technical Paper

Design Issues of the Switched Reluctance Motor Drive for Propulsion and Regenerative Braking in EV and HEV

2001-08-20
2001-01-2526
There is a growing interest in electric and hybrid electric vehicles (EV and HEV) due to their high efficiency and low emission. In EV and HEV, the characteristic of the traction motor is essential for the performance and efficiency of the EV and HEV. In this paper, the advantages of the extended constant power range characteristic of the traction motor for both propulsion and regenerative braking are analyzed. Simulation results are presented to verify the conclusions. Due to its several inherent advantages, especially its capability of having an extended constant power range, Switched Reluctance Motor (SRM) is proposed as the candidate of the traction motor in EV and HEV. The design methodology of SRM for achieving an extended constant power range and the control strategy of SRM for regenerative braking in EV and HEV are presented.
Technical Paper

Investigation of Hybrid Drive Trains for Railway Vehicles

2001-08-20
2001-01-2525
The concept of hybrid drive trains was first developed for automobiles. These drive trains allow achieving a minimum fuel consumption by properly matching the driving requirements and the engine characteristics. In this paper the authors analyze the possibility of extending this concept to railway vehicles. Basic hybrid railway vehicles are designed and discussed.
Technical Paper

Investigation of the Effectiveness of Regenerative Braking for EV and HEV

1999-08-17
1999-01-2910
The possibility of recovering vehicle kinetic energy is one inherent advantage of electric and hybrid electric vehicles. When a vehicle drives in heavy traffic, for example in New York City, more than half of the total energy is dissipated in the brakes. Therefore, recovering braking energy is an effective approach for improving the driving range of EV and the energy efficiency of HEV. In this paper, three different braking patterns are investigated for evaluating the availability of braking energy recovery. The results indicate that even without active braking control, a significant amount of braking energy can be recovered, and the brake system does not need much changing from the brake systems of conventional passenger cars.
Technical Paper

Parametric Design of the Drive Train of an Electrically Peaking Hybrid (ELPH) Vehicle

1997-02-24
970294
The operation of an electrically peaking hybrid vehicle (ELPH) can be divided into two basic modes. • Constant or cruising speed mode in which a small internal combustion engine (ICE) is used to power the vehicle. • Peak power mode in which the combination of an electric motor and ICE is used to supply peak power for acceleration and limited-duration steep hill climbing of the vehicle. A method, by which the engine size and the speed reduction ratio from the engine to drivewheels can be developed based on the cruising mode, is presented in this paper. The electric motor power rating and the motor gear ratio to the drive wheels can then be determined, based on the acceleration and gradeability. The results show that a simple single-gear transmission would be a good selection for overall performance.
Technical Paper

Topological Variations of the Inverse Dual Converter for High-Power DC-DC Distribution Systems

1992-08-03
929114
New dc to dc converter topologies are presented which are suitable for high density high power supplies. Topological variations of the basic inverse dual converter (IDC) circuit such as the transformer coupled, the multiphase and the multipulse derivation of the single phase IDC have been analysed and some simulation results have been presented. It has been shown in a recent publication [1] that the single phase IDC offers a buck-boost operation over wide range without transformer, bidirectional power flow, and complementary commutation of the switches. The topologies examined in this paper have additional features such as lower device and component stresses, and smaller filter requirements, resulting in smaller size and weight. Some performance and possible applications are also examined. Finally the IDCs for serial and parallel power distribution, and ac tapping of the IDC are discussed.
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