Design and Development Process for a Range Extended Split Parallel Hybrid Electric Vehicle

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). The goal of EcoCAR is for student engineers to take a GM-donated crossover SUV and reengineer it to reduce greenhouse gas emissions and petroleum energy use, while maintaining performance, safety and consumer appeal. 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 range-extended hybrid electric vehicle. HEVT is split up into three subteams to complete the competition and meet the requirements of the vehicle development process. The Mechanical subteam is tasked with modifying and refining the Year 1 component specifications and designs for packaging in the vehicle. The Electrical subteam is tasked with implementing a safe high voltage system on the vehicle including the design and development of a Lithium Iron Phosphate (LiFePO4) energy storage subsystem (ESS) donated by A123 Systems. The Controls subteam is tasked with modeling the Vehicle Technical Specifications (VTS) so that the subteams can make intelligent design decisions. The Controls subteam also used a controller Hardware-In-the-Loop (HIL) simulation setup running a real-time vehicle model against the controller hardware to test the HEVT-designed Hybrid Vehicle Supervisory Controller (HVSC). The result of this design process is an Extended-Range Electric Vehicle (EREV) 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). Using corn-based E85 fuel in North America for the 2015 timeframe and an average North American electricity mix, the well-to-wheels petroleum energy use and greenhouse gas emissions are reduced by 90 % and 30 % respectively when compared to the stock vehicle: a 4-cylinder, gasoline-fueled Vue XE. INTRODUCTION HEVT is in the process of developing and validating a hybrid architecture that was selected by the Year 1 team. This paper will first show how HEVT used the VDP to select the hybrid powertrain architecture in order to reduce petroleum energy use and greenhouse gas emissions. The paper will then explain the physical integration difficulties that were solved in software using computer aided design (CAD) with Unigraphics NX6 software, along with the limitations of the modified HEVT vehicle CAD model. In order to interface with and control the vehicle, HEVT added a National Instruments CompactRIO (cRIO) to act as a hybrid vehicle supervisory controller (HVSC). An explanation of the control strategy and the vehicle controller goals are shown, as well as the development of the vehicle control logic using HIL. The "VTREX" as the vehicle is known to the team (Virginia Tech Range-Extended Crossover), is compared to the baseline competition requirements and specifications as well as against the team-predicted VTS. Preliminary testing and validation of the vehicle are used to show safe operation and explain any discrepancies between the simulated model and actual vehicle results. HEVT plans to use Year 3 of EcoCAR to refine the HVSC while light-weighting components added to the vehicle to further reduce vehicle energy consumption and improve drivability. NOMENCLATURE HEVT: Hybrid Electric Vehicle Team of Virginia Tech