Development and Validation of an E85 Split Parallel E-REV 2011-01-0912

The Hybrid Electric Vehicle Team of Virginia Tech (HEVT) is participating in the 2009 - 2011 EcoCAR: The NeXt Challenge Advanced Vehicle Technology Competition series organized by Argonne National Lab (ANL), and sponsored by General Motors Corporation (GM), and the U.S. Department of Energy (DOE). Following GM's Vehicle Development Process (VDP), HEVT established team goals that meet or exceed the competition requirements for EcoCAR in the design of a plug-in extended-range hybrid electric vehicle. The competition requires participating teams to improve and redesign a stock Vue XE donated by GM. The result of this design process is an Extended-Range Electric Vehicle (E-REV) that uses grid electric energy and E85 fuel for propulsion. The vehicle design is predicted to achieve an SAE J1711 utility factor corrected fuel consumption of 2.9 L(ge)/100 km (82 mpgge) with an estimated all electric range of 69 km (43 miles) [1]. Using E85 fuel (corn-based in North America for the 2015 timeframe), the well-to-wheels petroleum energy use and greenhouse gas emissions are reduced by 90 % and 30 % respectively when compared to the stock 4-cylinder, gasoline-fueled Vue XE.

The powertrain selected by HEVT for the Virginia Tech Range-Extended-Crossover (VT_REX) is a split parallel architecture. On the front axle, there is a 2.4 L FlexFuel engine coupled to a 4-speed automatic transmission. On the rear axle there is an 80 kW Siemens AC Induction transaxle, liquid cooled, motor. The vehicle uses a 20 kWh (nominal) Lithium Iron Phosphate rechargeable energy storage system (RESS) using battery modules and controllers donated from A123 Systems. Using the grid electricity stored in the RESS, the 80 kW (peak) motor powers the vehicle for an estimated 69 km (43 miles) of all electric driving to a top speed of 160 kph (100 mph) which has only been modeled due to limitations in test facilities. Another smaller electric motor, a 15 kW (peak), AC induction, liquid cooled motor is mounted directly to the engine and belted to the engine crank. This motor allows the vehicle to perform engine idle start/stop and load leveling, which eliminates idle fuel use and increases the average operating efficiency of the FlexFuel engine.

This paper will detail how computer aided design (CAD) was used to integrate the above hybrid powertrain into the GM donated vehicle, while briefly touching on powertrain controls and safety. Vehicle test results will be reported from the Year 2 EcoCAR Competition that was held at GM's desert proving grounds in Yuma, AZ at which HEVT placed second overall. At Yuma, the vehicle performance was characterized in several areas - data was gathered for acceleration (0-100 kph and 80-110 kph), braking (100-0 kph), and fuel consumption. Limitations of the vehicle platform and further refinements for the competition vehicle will be discussed as well.