Validation of ADVISOR as a Simulation Tool for a Series Hybrid Electric Vehicle Using the Virginia Tech FutureCar Lumina

Abstract

Growing environmental and economic concerns have driven recent efforts to produce more fuel efficient and lower emissions vehicles. These goals are reflected by the Partnership for a New Generation of Vehicles (PNGV), a government, industry, and educational partnership in the United States. The major goal of this partnership is to have production vehicles by 2010 to address these concerns. Ideally, these vehicles will achieve three times the current fuel economy while drastically lowering emissions levels, without sacrificing the features, comfort, and performance of current conventional automobiles. Hybrid Electric Vehicles (HEVs) are automobiles which have both electric drivetrains and fuel-consuming powerplants. HEVs provide some of the most promising designs with the capability of meeting the PNGV goals. However, the development of these vehicles within the next ten years will require accurate, flexible simulation tools. Such a simulation program is necessary in order to quickly narrow the technology focus of the PNGV to those HEV configurations and components which are best suited for these goals. Therefore, the simulation must be flexible enough to encompass the wide variety of components which could possibly be utilized. Finally, it must be able to assist vehicle designers in making specific decisions in building and testing prototype automobiles. One of the most widely used computer simulation tools for HEVs is the ADvanced VehIcle SimulatOR (ADVISOR) developed by the National Renewable Energy Laboratory. This program is flexible enough to operate on most platforms in the popular MATLAB/SIMULINK programming environment. The structure of ADVISOR makes it ideal for interchanging a variety of components, vehicle configurations, and control strategies. Its modern graphical user interface allows for easy manipulation of various inputs and outputs. Also, the capability to quickly perform parametric and sensitivity studies for specific vehicles is a unique and invaluable feature of ADVISOR. However, no simulation tool is complete without being validated against measured vehicle data so as to ensure the reliability of its predictions. ADVISOR has been tested using data from a number of student-built HEVs from the top engineering colleges and universities around the country. As ADVISOR evolves to meet the changing needs of the vehicle design teams, this testing continues to ensure that ADVISOR maintains its usefulness as a simulation tool. One current validation study was recently completed at Virginia Tech using the FutureCar Challenge entry. This paper details the validation of ADVISOR using the Virginia Tech Lumina, a series HEV. The basic structure of the ADVISOR code is covered to ensure the validity of the vehicle modeling techniques used. The modeling process is discussed in detail for each of the major components of the hybrid system: transmission, electric motor and inverter, auxiliary power unit (fuel and emissions), batteries, and miscellaneous vehicle parameters. The integration of these components into the overall ADVISOR model is also described. The results of the ADVISOR simulations are then explained and compared to measured vehicle data on energy consumption, fuel efficiency, emissions output, and control strategy function for a variety of driving cycles and test procedures. Uncertainties in the measured data are discussed. Finally, the discrepancies between predicted and actual behavior are analyzed. This validation process shows that ADVISOR has extensive value as a simulation tool for HEVs. The existing limitations of the program are also detailed, with recommendations for improvement.