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Technical Paper

42V Automotive Power Systems

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

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

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

A Mild Hybrid Vehicle Drive Train with a Floating Stator Motor-Configuration, Control Strategy, Design and Simulation Verification

Significant amount of energy is lost in frequent braking, automatic transmission and engine idling for a conventional engine powered passenger car while driving in cities. In this paper, a mild hybrid vehicle drive train has been introduced. It uses a small electric motor with floating stator, called TRANSMOTOR and small and a battery pack. The transmotor functions as a generator, engine starter, frictionless clutch (electric torque coupler), regenerative braking and propelling. The mild hybrid drive train can effectively reduce the urban-driving fuel consumption by regenerative braking, eliminate of energy losses in conventional automatic transmission and engine idling. The drive train can use low voltage system (42V for example), due to the low electric power rating, and is more similar to conventional drive train than full hybrid vehicle. Therefore, less effort is needed to evolve it from conventional vehicles.
Technical Paper

A Versatile Computer Simulation Tool for Design and Analysis of Electric and Hybrid Drive Trains

This paper discusses a new computer simulation tool, V-Elph, which extends the capabilities of previous modeling and simulation efforts by facilitating in-depth studies of any type of hybrid or all electric configuration or energy management strategy through visual programming and by creating components as hierarchical subsystems which can be used interchangeably as embedded systems. V-Elph is composed of detailed models of four major types of components: electric motors, internal combustion engines, batteries, and vehicle dynamics which can be integrated to simulate drive trains having all electric, series hybrid, and parallel hybrid configurations. V-Elph was written in the Matlab/Simulink graphical simulation language and is portable to most computer platforms. A simulation study of a sustainable, electrically-peaking hybrid-electric vehicle was performed to illustrate the applicability of V-Elph to hybrid and electric vehicle design.
Technical Paper

Characterization of a Fuel Cell/Battery Hybrid System for Electric Vehicle (EV) Applications

A fuel cell/battery hybrid system for an electric vehicle was characterized under simulated driving conditions. The fuel cell is a 72 cell stack with 270 cm2 per cell of active electrode area. It has a continuous output of 1500 Watts and a peak power of 3000 Watts operating on hydrogen and atmospheric pressure air. The batteries are a tubular flooded lead-acid type. Seven 6 volt modules were connected in series with each module having a normal capacity of 205 Ahr. The fuel cell battery hybrid system was laboratory tested using a variable load battery cycler to simulate electric vehicle operation over a Modified Simplified Federal Urban Driving Schedule (MSFUDS). The fuel cell/battery hybrid operated successfully under steady state and dynamic conditions with the performance of the fuel cell only slightly degraded under the dynamic conditions of MSFUDS compared to steady state operation.
Technical Paper

DC Side Active Power Filters for Aircraft Electric Power Systems

In this paper a new dc-side active filtering system is proposed for aircraft electric power systems. The proposed active filter provides a continuous adjustable reactive power (both in phase and frequency) in the dc-link to meet the changing requirements which arise due to unbalanced and nonlinear loads at the 400(Hz) output. Furthermore, the active filter eliminate the additional capacitive kVA required in the dc-link caused by unbalanced and nonlinear loads. Results from a laboratory prototype active filter are also discussed.
Technical Paper

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

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

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

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

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

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).
Technical Paper

High Impedance Fault Detection Using Artificial Neural Network Techniques

Artificial Neural Network(ANN) techniques are used to develop a system to detect High Impedance Faults(HIFs) in electric power distribution lines. Encouraging results were observed with a simple Multi-layer Perceptron(MLP) trained with the backpropagation learning algorithm. Although the results are not significantly better than those reported with other algorithmic approaches, ANN techniques have potential advantages over the other approaches; namely, ability to train the system easily to accommodate different feeder characteristics, ability to adapt and so become a better detector with experience and better fault tolerance. When these features are incorporated, the system is expected to perform better than existing systems. The system we developed for the current phase, the training strategies used, the tests conducted and the results obtained are discussed in this paper. Also background discussions on existing HIF detection techniques, and ANN techniques can be found in this paper.
Technical Paper

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

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

Investigation of Hybrid Drive Trains for Railway Vehicles

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

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.

Modern Electric, Hybrid Electric, and Fuel Cell Vehicles

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
Journal Article

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

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.
Technical Paper

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

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

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

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

Systematic Design of Fuel Cell Powered Hybrid Vehicle Drive Train

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

Vision Assisted Tractor Guidance for Agricultural Vehicles

Computer algorithms were developed for generating the guidance parameters necessary to steer an agricultural tractor. A variety of field operations were considered in order that the guidance program be suited for general applications including travel in curved rows and following a single edge. Testing of the guidance algorithm was performed in the laboratory using simulated and videotaped images of rowcrops and tilled soil. From the images, yaw angle change of the tractor, direction value and offset error were computed. Prediction of the direction value and offset error compared well to measured values. Accuracy of the direction value was within +/- 0.5 degrees while the offset error was within +/- 0.05 meters. Good performance was observed for straight and curved rows as well as following a single edge.