Sometime over this past summer, the Virginia Tech EcoCAR 2 Team’s vehicle, Mary the Malibu, developed a ground fault that crippled its ability to run in EV (electric vehicle) mode. They spent roughly four months troubleshooting during the fall semester. But just before winter break, they received an early holiday present – a running vehicle!
Once again, Mary is mobile!
They were able to find an issue with their rear traction motor inverter and sent it off to UQM for repairs. After getting the inverter back, they were able to re-integrate it into their vehicle and use the high voltage system to run the rear traction motor. Being up-and-running again in EV mode is a big step in the right direction. The team is now doing some closed-course vehicle testing and collecting a lot more data. Using this data, they will be able to refine their control code and increase EV efficiency.
Virginia Tech’s next major milestone is getting their front powertrain working. In place of a torque converter, the team has a custom P2 generator motor built by local sponsor Kollmorgen sitting between the engine and the transmission. This is Mary’s crown jewel, which can be put into gear like a torque converter or put in neutral to generate 28 kW of electricity to recharge the battery system in the trunk. However, because it’s a completely custom motor, it comes with a unique set of benefits and challenges.
Mainly, there has been a slight issue with transmission fluid leaking in. The team has since narrowed the leak’s cause down to a few possibilities and are collaborating with headlining sponsor General Motors to see which stock components may be conflicting with the new system. Additional data has come from validating their engine controls outside the vehicle using an engine test stand. This testing method is helping the team replicate the leak outside the vehicle and further troubleshoot the issue.
Once Virginia Tech validated their engine components, they were able to re-install their engine and get on the road. As Mary is intended to run as a series parallel plug-in hybrid electric vehicle, this will give her a 40-mile all electric range and a +/- 100-mile charge sustaining charge.