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The objective of this work is to provide a relatively simple battery energy storage and loss model that can be used for technology screening and design/sizing studies of hybrid electric vehicle powertrains. The model dynamic input requires only power demand from the battery terminals (either charging or discharging), and outputs internal battery losses, state-of-charge (SOC), and pack temperature. Measured data from a vehicle validates the model, which achieves reasonable accuracy for current levels up to 100 amps for the size battery tested. At higher current levels, the model tends to report a higher current than what is needed to create the same power level shown through the measured data. Therefore, this battery model is suitable for evaluating hybrid vehicle technology and energy use for part load drive cycles.

The Hybrid Electric Vehicle Team of Virginia Tech (HEVT) is participating in the 2005 - 2007 Challenge X advanced technology vehicle competition series, sponsored by General Motors Corporation, the U.S. Department of Energy, and Argonne National Lab. This report documents the Equinox REVLSE (Renewable Energy Vehicle, the Larsen Special Edition) design and specifies how it meets the Vehicle Technical Specifications (VTS) set by Challenge X and HEVT through simulation and test results. The report also documents the vehicle control development process, specifies the control code generation, demonstrates an analysis of hybrid powertrain losses, and presents the REVLSE vehicle balance in its intended market.

For a hybrid electric vehicle (HEV) with an internal combustion engine, simply operating the engine in its regions of high efficiency does not guarantee the most fuel efficient operational strategy. This paper defines an operational strategy for a HEV through calculating individual powertrain component losses and comparing those losses across possible operational modes. The results of these calculations define how the vehicle can decrease fuel consumption while maintaining low vehicle emissions. The results presented are meant only to define a literal strategy; that is, an understanding as to why the vehicle should operate in a certain way given driver demands, vehicle speed, and powertrain limitations.

The Hybrid Electric Vehicle Team of Virginia Tech (HEVT) is participating in the 2005 - 2008 Challenge X advanced technology vehicle competition series, sponsored by General Motors Corporation, the U.S. Department of Energy, and Argonne National Lab. This paper presents the Equinox REVLSE (Renewable Energy Vehicle, the Larsen Special Edition) design, simulation and modeling results to set the Vehicle Technical Specifications (VTS), improvements made to approach the 99 % buyoff level of vehicle readiness, and the HEVT hybrid control strategy that selects vehicle propulsion modes to meet VTS. The paper also compares the REVLSE to the production Equinox.

Fuel cell system models are key tools for automotive fuel cell system engineers to properly size components to meet design parameters without compromising efficiency by over-sizing parasitic components. A transient fuel cell system-level model is being developed that includes a simplified transient thermal and parasitics model. Model validation is achieved using a small 1.2 kW fuel cell system due to its availability. While this is a relatively small stack compared to a full size automotive stack, the power, general thermal behavior, and compressor parasitics portions of the model can be scaled to any number of cells with any size membrane area. With flexibility in membrane size and cell numbers, this model can be easily scaled to match full automotive stacks of any size. The electrochemical model employs a generalized polarization curve to approximate system performance and efficiency parameters needed for the other components of the model.

In the past few years, the price of petroleum based fuels, especially vehicle fuels such as gasoline and diesel, have been increasing at a significant rate. Consequently, there is much more consumer interest related to reducing fuel consumption of conventional and hybrid electric vehicles (HEVs). The “pulse and glide” (PnG) driving strategy is first applied to a conventional vehicle to quantify the fuel consumption benefits when compared to steady state speed (cruising) conditions over the same time and distance. Then an HEV is modeled and tested to investigate if a hybrid system can further reduce fuel consumption with the proposed strategy. Note that the HEV used in this study has the advantage that the engine can be automatically shut off below a certain speed (∼40 mph, 64 kph) at low loads, however a driver must shut off the engine manually in a conventional vehicle to apply this driving strategy.