Powertrain Design to Meet Performance and Energy Consumption Goals for EcoCAR 3 2014-01-1915
The Hybrid Electric Vehicle Team (HEVT) of Virginia Tech is excited about the opportunity to apply for participation in the next Advanced Vehicle Technology Competition. EcoCAR 3 is a new four year competition sponsored by the Department of Energy and General Motors with the intention of promoting sustainable energy in the automotive sector. The goal of the competition is to guide students from universities in North America to create new and innovative technologies to reduce the environmental impact of modern day transportation. EcoCAR 3, like its predecessors, will give students hands-on experience in designing and implementing advanced technologies in a setting similar to that of current production vehicles. The primary goals of the competition are to improve upon a conventional internal combustion engine production vehicle by designing and constructing a powertrain that accomplishes the following:
Reduce Energy Consumption
Reduce Well-to-Wheel (WTW) GHG Emissions
Reduce Criteria Tailpipe Emissions
Maintain Consumer Acceptability in the area of Performance, Utility, and Safety
Meet Energy and Environmental Goals, while considering Cost and Innovation
This paper presents results from several modeling problems and conceptual vehicle designs. First, the power and energy at the wheels to meet acceleration and gradeability performance requirements are documented. Next, to compare several different fuel sources including E10, E85, and B20 fuels for a given base conventional vehicle, drive cycle fuel energy consumption is documented and used to find WTW GHG impact. The conventional vehicle modeling is validated by comparing to measured fuel consumption and acceleration performance data from a conventional vehicle. To compare a battery electric vehicle (BEV) to the conventional vehicle, drive cycle electric grid energy consumption and GHG results from sizing a motor and battery to meet performance and range requirements are found. Very significant vehicle light-weighting (300 kg) would be required to accommodate a battery system large enough to meet the range goal of 320 km (200 mi). From here, the advantages of powertrain electrification are examined by constructing a Series Hybrid Electric Vehicle model. The model is used to size engine/generator and battery components in the powertrain. Additionally, different hybrid vehicle energy management strategies are explored to evaluate overall charge balance operation. Waste heat conversion to meet electric accessory loads is evaluated as an innovative technology that can also reduce vehicle energy consumption.
Finally, a powertrain design is selected to meet the goals of the competition. After exploring many powertrain configurations and energy sources, this paper details three hybrid powertrains to find a combination capable of meeting the target energy consumption and WTW GHG emissions while also meeting all of the performance goals. The first of these powertrains is sized to model a typical belted alternator starter (BAS) system and shows small improvements over a conventional vehicle. The next design is a parallel through the road hybrid that is sized to meet most power needs with an electric motor and a smaller IC engine. This case comes closer to the design goals, but still falls short on total energy consumption. Lastly, the battery and motor size are increased to allow a charge depleting mode, adding stored grid electricity to the energy sources. This electric energy only mode is able to displace a large amount of the fuel energy consumption based on the SAE J1711 method for determining utility factor weighted energy consumption of a plug-in hybrid electric vehicle. The final design proposed by HEVT for this modeling report is a Parallel Plug-In Hybrid Electric Vehicle using E85 fuel and a 7 kWh battery to provide an all-electric charge depleting range of 34 km (21 mi).