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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.

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 of Virginia Tech (HEVT) is currently developing a control strategy for a parallel plug-in hybrid electric vehicle (PHEV). The hybrid powertrain is being implemented in a 2016 Chevrolet Camaro for the EcoCAR 3 competition. Fuzzy rule sets determine the torque split between the motor and the engine using the accelerator pedal position, vehicle speed and state of charge (SOC) as the input variables. The torque producing components are a 280 kW V8 L83 engine with active fuel management (AFM) and a post-transmission (P3) 100 kW custom motor. The vehicle operates in charge depleting (CD) and charge sustaining (CS) modes. In CD mode, the model drives as an electric vehicle (EV) and depletes the battery pack till a lower state of charge threshold is reached. Then CS operation begins, and driver demand is supplied by the engine operating in V8 or AFM modes with supplemental or loading torque from the P3 motor.

Rapid adoption of battery electric vehicles means improving the energy consumption and energy efficiency of these new vehicles is a top priority. One method of accomplishing this is regenerative braking, which converts kinetic energy to electrical energy stored in the battery pack while the vehicle is decelerating. Coasting is an alternative strategy that minimizes energy consumption by decelerating the vehicle using only road load. A battery electric vehicle model is refined to assess regenerative braking, coasting, and other deceleration strategies. A road load model based on public test data calculates tractive effort requirements based on speed and acceleration. Bidirectional Willans lines are the basis of a powertrain model simulating battery energy consumption. Vehicle tractive and powertrain power are modeled backward from prescribed linear velocity curves, and the coasting trajectory is forward modeled given zero tractive power.

This paper describes the design and construction of a fuel cell hybrid electric vehicle based on the conversion of a five passenger production sedan. The vehicle uses a relatively small fuel cell stack to provide average power demands, and a battery pack to provide peak power demands for varied driving conditions. A model of this vehicle was developed using ADVISOR, an Advanced Vehicle Simulator that tracks energy flow and fuel usage within the vehicle drivetrain and energy conversion components. The Virginia Tech Fuel Cell Hybrid Electric Vehicle was tested on the EPA City and Highway driving cycles to provide data for validation of the model. Vehicle data and model results show good correlation at all levels and show that ADVISOR has the capability to model fuel cell hybrid electric vehicles.

The Hybrid Electric Vehicle Team of Virginia Tech (HEVT) has integrated a proton exchange membrane fuel cell as the auxiliary power unit of a series hybrid design to produce a highly efficient zero-emission vehicle. A 1997 Chevrolet Lumina sedan, renamed ANIMUL H2, carries this advanced powertrain, 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 supplies the average power demand and to sustain the battery pack state-of-charge within a 40-80% window. To optimize system efficiency, a load-following strategy controls the fuel cell power level. The vehicle weighed 2000kg (4400lb) and achieved a combined city/highway fuel economy of 9L/100 km or 26 mpgge (miles per gallon gasoline equivalent).

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).

The Hybrid Electric Vehicle Team of Virginia Tech (HEVT) is participating in the 2012-2014 EcoCAR 2: Plugging in to the Future 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 goals of the competition are to reduce well-to-wheel (WTW) petroleum energy consumption (PEU), WTW greenhouse gas (GHG) and criteria emissions while maintaining vehicle performance, consumer acceptability and safety. Following the EcoCAR 2 Vehicle Development Process (VDP), HEVT is designing, building, and refining an advanced technology vehicle over the course of the three year competition using a 2013 Chevrolet Malibu donated by GM as a base vehicle.