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The Hybrid Electric Vehicle Team of Virginia Tech is one of 15 schools across the United States and Canada currently competing in EcoCAR 2: Plugging In to the Future. EcoCAR 2 is a three year competition that mimics GM's Vehicle Development Process (VDP): design, build, then refine. The first step in the design process is the selection of a powertrain architecture. In the architecture selection process, HEVT considered three options: a Battery Electric Vehicle (BEV), a Series Plug-in Hybrid Electric Vehicle (PHEV), and a Series-Parallel PHEV. The team chose the Series-Parallel PHEV based on powertrain modeling and simulation and CAD packaging analysis. Next, the team looked at a variety of component combinations and selected the one that offered the best capacity to meet competition and team goals. These components are then packaged in the CAD model to plan for component integration. As this integration was happening, a control system was also being developed.

This paper covers the development of a closed loop transaxle synchronization algorithm which was a key deliverable in the control system design for the L3 Enigma, a Battery Dominant Hybrid Electric Vehicle. Background information is provided to help the reader understand the history that lead to this unique solution of the input and output shaft synchronizing that typically takes place in a manual vehicle transmission or transaxle when shifting into a gear from another or into a gear from neutral when at speed. The algorithm stability is discussed as it applies to system stability and how stability impacts the speed at which a shift can take place. Results are simulated in The MathWorks Simulink programming environment and show how traction motor technology can be used to efficiently solve what is often a machine design issue. The vehicle test bed to which this research is applied is a parallel biodiesel hybrid electric vehicle called the Enigma.

Large sport utility vehicles have relatively low fuel economy, and thus a large potential for improvement. One way to improve the vehicle efficiency is by converting the drivetrain to hydrogen fuel cell power. Virginia Tech has designed a fuel cell hybrid electric vehicle based on converting a Chevrolet Suburban into an environmentally friendly truck. The truck has two AC induction drive motors, regenerative braking to capture kinetic energy, a compressed hydrogen fuel storage system, and a lead acid battery pack for storing energy. The fuel cell hybrid electric vehicle emits only water from the vehicle. The fuel cell stacks have been sized to make the 24 mpg (gasoline equivalent) vehicle charge sustaining, while maintaining the performance of the stock vehicle. The design and integration challenges of implementing these systems in the vehicle are described.

The Hybrid Electric Vehicle Team (HEVT) of Virginia Tech has designed a fuel cell hybrid electric vehicle to compete in the 2002 FutureTruck Challenge. This year the competition is focused on reducing tailpipe emissions and increasing vehicle efficiency without compromising vehicle performance. The team has converted a Ford Explorer into an environmentally friendly truck. Our truck has an AC induction drive motor, regenerative braking to capture kinetic energy, compressed hydrogen fuel storage system, and a lead acid battery pack. The Virginia Tech FutureTruck emits only water from the vehicle. The fuel cell stacks have been sized to make the 35.8 mpg (combined adjusted gasoline equivalent) vehicle charge sustaining.

The Virginia Tech Hybrid Electric Vehicle Team (HEVT) has integrated a proton exchange membrane (PEM) fuel cell as the auxiliary power unit (APU) of a series hybrid design to produce a highly efficient zero-emission vehicle (ZEV). This design is implemented in a 1997 Chevrolet Lumina sedan, renamed ANIMUL H2, using an efficient AC induction drivetrain, regenerative braking, compressed hydrogen fuel storage, and an advance lead-acid battery pack for peak power load leveling. The fuel cell is sized to supply the average power demand and to sustain the battery pack state-of-charge (SOC) within a 40-80% window. To optimize system efficiency, the fuel cell is driven with a load-following control strategy. The vehicle is predicted to achieve a combined city/highway fuel economy of 4.3 L/100 km or 51 mpgge (miles per gallon gasoline equivalent).

Improving fuel economy and overall vehicle emissions are very important in today's society with strict new regulations throughout the world. To help in the education process for the next generation of design engineers, this paper seeks to define a powertrain model created and developed to help users understand the basics behind hybrid vehicles and the effects of these advanced technologies. One of the main goals of this research is to maintain a simplified approach to model development. The 1 Hz model described within this work aims to allow energy to be simply and understandably traced through a hybrid powertrain. Through the use of a “backwards” energy tracking method, demand for a drive cycle is found, and, after tracing the energy demand through each powertrain component, the resulting fuel to meet vehicle demand and associated powertrain losses is found.

The Hybrid Electric Vehicle Team (HEVT) of Virginia Tech is ready to compete in the Year 3 Final Competition for EcoCAR 2: Plugging into the Future. The team is confident in the reliability of their vehicle, and expects to finish among the top schools at Final Competition. During Year 3, the team refined the vehicle while following the EcoCAR 2 Vehicle Development Process (VDP). Many refinements came about in Year 3 such as the implementation of a new rear subframe, the safety analysis of the high voltage (HV) bus, and the integration of Charge Sustaining (CS) control code. HEVT's vehicle architecture is an E85 Series-Parallel Plug-In Hybrid Electric Vehicle (PHEV), which has many strengths and weaknesses. The primary strength is the pure EV mode and Series mode, which extend the range of the vehicle and reduce Petroleum Energy Usage (PEU) and Greenhouse Gas (GHG) emissions.