Mathematical modeling, HIL testing and in-vehicle validation of E85 fueled two-mode hybrid electric vehicle
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Today, the limits of petroleum resources (and rising gasoline prices) have globally become a reason for concern, and it is commonly thought throughout the world that current automotive technology will need to be adapted or replaced for the future. Efforts are underway worldwide to improve current vehicle technologies to make automobiles more fuel efficient, environmentally friendly, powerful, etc. In this context, EcoCAR: The Next Challenge was an international, collegiate vehicle engineering competition for North American colleges and universities sponsored by the US Department of Energy and General Motors Corporation, and others. Texas Tech University was one of the sixteen universities that competed in this three year collegiate advanced vehicle technology competition where teams were challenged to re-engineer a GM donated vehicle to achieve improved fuel economy and reduced emissions while maintaining consumer acceptability in the areas of stock performance, utility and safety. This dissertation presents an overview of the development of the vehicle design with industry standard vehicle development process (VDP). A two-mode hybrid powertrain was proposed to keep the vehicle performance, improve fuel economy and reduce the impact to the environment. The powertrain utilizes a GM 1.6L family 1 engine, a GM 2-mode front-wheel drive (FWD) transaxle and a 12.9 kWh A123 Systems high voltage battery pack. The proposed 2-mode hybrid electric vehicle was built by integrating the proposed hybrid powertrain into a GM donated vehicle. The design process started from the architecture selection with the use of PSAT software. Modeling and simulation of two-mode hybrid using model based design (MBD) process was performed. The Mathworks Simulink, SimDriveline and Stateflow provided an environment for modeling selected architecture and powertrain components. A vehicle performance target was established through vehicle technical specifications (VTS). Once model was verified in Software-in-the-loop (SIL), hardware in-the-loop (HIL) testing was performed with the use of a National Instruments PXI and a dSPACE MicroAutoBox (MABX). For the hybrid control algorithm development, a rule-based control method is used to consider both the 2-mode transmission dynamic model and the powertrain component specifications and constraints. For rapid control system prototyping, MABX was added as a supervisory controller to interface with the stock electronic control units to accomplish the desired hybrid control functions. In this way going from mathematical models to lab-based tests with HIL, then by moving to in-vehicle testing of the vehicle’s on board software, a realistic vehicle propulsion controller was developed. The proposed hybrid vehicle is capable of EV drive, regenerative braking, two electric variable transmission modes, engine auto-stop, and engine optimal operation. The prototype vehicle was tested on road to verify the simulation model, vehicle performance and fuel economy, the 2-mode transmission dynamic model and the hybrid control algorithm.