GM FYI Blog

By Irene Berry
Guest Blogger

Editor’s Note: Last week, we heard from Challenge X winning team Mississippi State University. Today, we take a look at what it was like to participate in this year’s competition by third-place team Virginia Tech.

In the beginning of the Challenge X competition, The Hybrid Electric Vehicle Team (HEVT) of Virginia Tech decided to use a split-parallel hybrid architecture that would use E85 fuel in its Equinox REVLSE. To achieve this design, HEVT uses two electric motors. The high voltage belted alternator/starter (BAS) is belted directly to a Saab 2.3-L engine coupled to a five-speed manual transmission to power the front wheels, while a rear traction motor supplies power to the rear wheels in order to maintain all-wheel-drive capabilities and provide performance assist. This setup allows the vehicle to use both motors in parallel power paths to assist the engine, or allows use of a series power path when the BAS is used to charge the 336V NiMH battery pack.

During Challenge X 2007, HEVT placed third overall while winning awards for best written technical reports and lowest well-to-wheels petroleum energy use. Here are four days of competition from HEVT’s perspective:

Day 1: We arrive at Milford at 7 a.m. to tackle the list from technical and safety inspection. After spending way too long welding, unwelding, and finally bending the exhaust to meet 7-inch ground clearance, we finally start the engine and it won’t do anything except idle: time for Controls Team to break out the magic screwdrivers and start freaking out. They kick us out at 8:00 a.m. Plus, we find out that Rick Wagoner is supposed to drive our car at noon the following day.

Day 2: We get in at 7 a.m. with a list of things to check. Finally, at 8:20 a.m., we find the problem and are on the road. Wagoner is going to drive our car, not Wisconsin’s. Unfortunately, the car stalls in the middle of a driving circle while he is driving. When keying-start doesn’t work, he keys-off, the battery disconnects, and we’re stuck there for three minutes. The good news is that Wagoner is a really nice and down-to-earth guy. “Driver error,” he says. Afterward, the driver information center and data acquisition computer stopped working. We throw together a LabVIEW data logger, and are off to the braking and acceleration events.

Day 3: We get through the traction, AVL Drive Quality event, noise, and handling events. The car seems to be running fine, until we realize the clutch sensor is failing. We fix that, then end the day realizing that the idle-stop wiring is messed-up … again.

Day 4: Three of us get in at 7 a.m. with a plan: Instead of debugging further, we rebuild a slight adaptation of the idle-stop wiring using the National Instruments CompactRIO instead of a relay. By 7:30 a.m., we’re done and the car is off to the fuel-economy event. Next is emissions. The driver for the event finds the car CD and listens to “Tech Triumph” and the “Hokie Pokie” the entire time. Towing is the final event: 16 percent grade with 2,500-pound tow. The car does awesome until a front halfshaft breaks at the very top of the hill.