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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.
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

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.
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