There and Back Again: An HEVT Tale

Phew. What a trip.

Over the long weekend, we were hosted by MathWorks in Natick, MA, for the EcoCAR 2 Fall Workshop. In total, we participated in approximately 26 hours of workshops, trainings and seminars — all to prepare us for an amazing year.

Team and subteam leaders were set upon individual tracks according to their area of work. Engineers had training with software such as Matlab, Simulink, QNX and Vector to name a few. Business and communications reviewed competition deliverables and worked through product management, sponsor relations, media relations and video production classes.

“Since we mainly operate as a senior-design project, Fall Workshop is vital to bringing our new subteam leaders up to speed,” said team leader, Eli White. “It gives a crash course in these complicated software programs that our team will use throughout the year.”

As Eli said, we have 22 new team members that need to get acclimated to the competition and learn how to effectively use these technologies. Overcoming this learning curve early in the semester is essential to our success in Year 3. As expected, this feat does not come without its challenges.

“I was really interested in working with this big-time software since I had limited experience with it,” said controls subteam leader, Billy Dvorkin. “I was a little overwhelmed in the beginning, but the Matlab training at Fall Workshop has given me a ground foundation of skills to build on.”

Lucas Shoults speaks with GM representatives.

Don’t get us wrong, we weren’t training the whole time. Thursday night we attended a sponsor social to network with sponsoring companies in the hopes of jobs and internships. Saturday evening we got a chance to go into Boston and have a dinner at the Cheers Boston restaurant near the famed Faneuil Hall. It was great to sight see a bit and relax after three full days of training. 

We want to thank our host MathWorks again for their continued support with EcoCAR 2 and a great Fall Workshop. 

It’s now time get down to business and put our new-found knowledge to test. Get ready for some upcoming build updates as we begin to refine our precious Mary the Malibu.

The Road to EV Mode

After a lot of hard work, we have commissioned our A123 battery pack! There were a lot of steps to get to this point, and the electrical subteam has been busy all year preparing for this moment.

“Commissioning the battery pack essentially means that our pack has been deemed safe by A123,” said electrical subteam leader Brian Kelly. “We are now able to distribute power to the rest of the vehicle.”

To get to this point we had to complete certain steps. The first was to become familiar with the batteries. “We needed to know how they work and how they communicate with each other,” Brian said. The electrical subteam first completed the bench testing checklist where the batteries were literally placed on a bench so the team knew how to safely work with high and low voltage systems. The low voltage harness was connected to the high voltage batteries in a series and we performed different tests.

The next step was to complete the internals checklist. This is when the Energy Storage System (ESS), the actual structure that holds the batteries, was built. “We first built the ESS with wood so we could see what parts of the ESS we could build outside the car and the parts that we had to weld while in the car,” said electrical subteam member Tyler Erickson.

The ESS was built out of 20 gauge steel along with ⅛” tube steel, painted in maroon and orange, and then covered in Kapton tape. The Kapton tape isolates the steel from high voltage so the batteries are completely separated from any passenger in or out of the vehicle.

Make That Rear Traction Motor Spin

The controls subteam has been working tirelessly with the control code to spin our rear traction motor (RTM). In the early hours of spring morning, the team’s hard work paid off, and we saw the RTM spin for the first time!

The 125 kW rear traction motor is mounted on the rear subframe, which enables us to power the vehicle in all electric mode. First, the mechanical subteam made modifications to the rear subframe and designed mounts for the motor and single speed transmission that it’s coupled to. Then the electrical subteam stepped in to ensure that all of the high-voltage wiring was connected correctly and safely from the energy storage system to the inverter and then to the RTM.

The controls team then had to come in and make it all work together. Throughout the year the team has been creating and testing the code for this very moment. “We have been developing the control code since year 1 using logic blocks in MATLAB Simulink,” said controls subteam leader Kyle Caroncino.

The control code is loaded onto the MicroAutoBox, graciously donated by competition platinum-level sponsor dSPACE. The control code is then manipulated to satisfy the necessary “component-enable” conditions based on the readiness level of the vehicle. Only after each of the components involved have been properly enabled will the battery send high-voltage electricity to the rear-traction motor.

After many long nights working in the Ware Lab, the team was able to send commands to the RTM and spin the wheels!  Check out the video at the link below!

“It’s neat seeing all of the components we’ve been installing over the course of the year actually working together,” Kyle said. “It’s a visual recognition of our hard work.”

With less than two weeks from competition, we are working hard to make sure we have a running vehicle for competition. The RTM signifies a huge milestone for the team and we’re excited to see all of the other components come together.

Build Update 4.19.13

Last Friday, we received the finalized half shafts for the BorgWarner transmission we are using in the rear of the vehicle. Now that these shafts are the correct length, installation was as simple as sliding the splined shafts into one another.

With these parts installed we are able to mechanically link the transmission to the wheel hubs and drive the vehicle using the rear traction motor. With the addition of the half shafts we were also able to fill the BorgWarner transmission with fluid and assemble the entire rear cradle into the vehicle. This marks a major milestone, as it was the last mechanical driveline component to be installed in the car. Now it's off to the controls and electrical teams for testing and refinement!

Build Update 4.12.13

Last week we returned the P2 motor/generator to team sponsor Kollmorgen to fix fitment issues. Kollmorgen was very quick with the alterations and we received it back the next day.

With the P2 back in the lab, we were able to reassemble the front powertrain. Here’s to hoping the front engine, P2 and transmission assembly never have to come out of the car again! We started with the assembly of the P2 to the transmission by routing the three-phase and signaling wires from the P2 through the transmission and its bell housing. With these two connected, we sealed the P2 coolant fittings and the holes where the wires protruded.