Control and Testing of a 2-Mode Front-Wheel-Drive Hybrid-Electric Vehicle

The new General Motors 2-mode hybrid transmission for front-wheel-drive vehicles has been incorporated into a 2009 Saturn Vue by the West Virginia University EcoCAR team. The 2-mode hybrid transmission can operate in either one of two electrically variable transmission modes or four fixed gear modes although only the electrically variable modes were explored in this paper. Other major power train components include a GM 1.3L SDE turbo diesel engine fueled with B20 biodiesel and an A123 Systems 12.9 kWh lithium-ion battery system. Two additional vehicle controllers were integrated for tailpipe emission control, CAN message integration, and power train hybridization control. Control laws for producing maximum fuel efficiency were implemented and include such features as engine auto-stop, regenerative braking and optimized engine operation. The engine operating range is confined to a high efficiency area that improves the overall combined engine and electric motor efficiency. Simulation results using Powertrain System Analysis Toolkit (PSAT) indicate fuel economy of 28.4/29.4 mpgge over the customized Morgantown Urban Drive Schedule (MUDS)/Route 19 Highway (R19HW), 14.6 second 0-60 mph and 8.6 second 50-70 mph acceleration time. The on-road test results indicated fuel economy of 24.5/31.5 mpgge over the MUDS/R19HW cycles, 16 seconds 0-60 mph and 10 seconds 50-70 mph acceleration time.