The EV1 is currently having a next generation Ballard Sapphire 150kW Integrated PowerTrain (IPT) fitted and installed. We’re currently fabricating new motor mounts and they will soon be welded into the frame. Once the mounts are welded and the wiring installed we’ll be out on the test track again!
What do you do with 50 undergraduate students in the first year of a vehicle competition that is strictly modeling? Find a vehicle for them to work on! Wisconsin received an EV1 from General Motors (GM) when they were in the process of dismantling and recycling them at the end of the EV1 lease program. GM generously donated disabled EV1′s to any university that requested one. In addition to removing the high voltage batteries, GM had removed the main drive controller, the power steering pump controller, the brake controller and the body controller – they intended the vehicles to be looked at and studied, but never driven.
So in a year when most Madison students would have turned their interest to a favorite Wisconsin pastime – BEER, a special group of engineering students took on the challenge of reincarnating our bright red EV1. This task would be as difficult as building a hybrid while offering new challenges to the students. This would be the first time they would be working on a charge-depleting vehicle – let alone a fully electric one.
Several veteran hybrid team members started the project in September of 2004. With no place to store or display the EV1, the rally cry was “fix it or scrap it”. The first feat was creating a 380 volt battery pack. The original battery pack mounted between and behind the two seats creating a large T-shaped battery box. Removing the battery tray the first time was easy since the batteries had been removed before delivery. Upon inspection of the battery tray, one of our students had an idea. They proceeded to the battery room and retrieved a nickel metal hybrid battery originally used in the electric Ranger project that had since been donated to our university by Ford Motor Company. THE BATTERIES FIT – General Motors had actually used an industry standard battery casing. With much anticipation, all of the batteries were uncrated and hauled from the battery room to the garage. This took awhile, as each battery weighed approximately 80 lbs. But wait, we were SIX batteries short – now what? Could we order them? Sure, but they were $2800 each and you have to order a minimum of 26. That’s $72,800 – OUCH!! After a significant amount of brainstorming, Wisconsin contacted our counterparts at the University of West Virginia (they were one of about 6 universities to have received the batteries through the Ford donation) to see if we could purchase six precious batteries from them. To our surprise, the Mountaineers (West Virginia school mascot) donated the batteries to the Wisconsin reincarnation project. Now we had a complete 95 amp-hr nickel metal hydride pack – this equaled the capacity of the best EV1 that General Motors had produced.
The next major component that needed to be replaced was the motor controller. Wisconsin had a spare Solectria DMOC 445, the same controller that is utilized in our 2004 FutureTruck to drive an identical EV1 motor. The only drawback was that the Solectria was rated for 78 kW and the motor was rated for 105 kW – Tim Taylor (of Home Improvement fame) would not be happy, but Wisconsin decided that it was our only alternative. After mounting the controller and adding the appropriate speed pick-up to the original motor in the EV1, we were abruptly disappointed as the controller only made the motor hum and shake. Upon contacting Solectria and giving them the model number of both controllers, we were informed that the control boards were 4 revisions apart and that they did not know how to convert the calibration parameters from our FutureTruck controller into the one in our EV1.
Frustrated and in disbelief, the team was forced to put the EV1 project on hold. Without a motor controller, the EV1 reincarnation was stalled. Then, while working with Ballard Power Systems to arrange for the purchase of an IPT (Integrated Powertrain) for our Challenge X program, Ballard graciously offered another Integrated Powertrain to Wisconsin as a heart transplant for our EV1. This was a great first step as it was the same unit that would ultimately be hybridizing Wisconsin’s Challenge X vehicle.
However, using the Ballard unit posed ONE LARGE mechanical hurdle – the suspension/ motor sub-frame had to be drastically modified. The original EV1 powertrain mounted the motor above the sub-frame and used an in-line gear reduction to transfer the torque below the motor where the axle shafts connected. Since the Ballard unit utilizes a hollow shaft motor with planetary gear reduction and differential, the subframe would have to be widened so both would fit inside.
The Wisconsin Hybrid team had experience in aluminum structures as they have created 3 different aluminum truck frames in the last 5 years. Using stiff, heavy pieces of steel, the students created a welding jig that bolted to all the sub-frame’s critical mounting points. Next, they took a perfectly good sub-frame and cut it into 3 pieces! The new design lowered the sub-frames axial members to be below the main A-arm mounting point while the cross member that holds the steering rack was left in its original location. After adding several stiffeners and adding towing points to the sub-frame, the IPT was lowered into place.
Meanwhile, the controls group was rewiring the vehicle and re-engineering the logic for the controllers that had been removed before delivery. In particular, the rear brakes are activated using a ball-screw actuator. Besides having to engineer the Hbridge driver for the motors, calibration between brake pedal position and braking resistance had to be correlated. They also programmed a PIC micro-controller to control the dash, security and HVAC. After the IPT was installed, a Freescale MPC 555 was integrated into the vehicle as the interface between the driver’s request and the IPT.
With everything checked and doublechecked, it was time to try to spin the wheels!!! To our dismay, we couldn’t get the IPT to ‘wake-up’. Although Ballard had been overly helpful in answering all of our technical questions in a timely manner, this problem could not be solved via email or phone calls. After trying for several days, it was time for a road trip. We loaded the EV1 into our rig and headed to Ballard Power Systems Inc. located in Dearborn, Michigan. The trip had a double purpose as we were also attending SAE International Congress. While at Ballard, we discovered that we had installed the IPT backwards! Since the IPT utilizes a mechanical oil pump (no lubrication while spinning in reverse), it wasn’t as simple as reversing the control logic. A quick look on the CAN bus revealed an incorrect software version on the IPT controller and a record length error on a CAN message. After a couple of memory stick file exchanges, an IPT reflash, and a quick update on the EV-1 code, the unit was up and running. The EV1 moved under its own power and the reincarnation was almost complete.
We returned to Madison with a bittersweet victory: the EV1 lived but required the reversal of the IPT. During April and May, the team worked hard to correct the orientation of the IPT, incorporated some suggestions provided by Ballard and finalized the wiring and EV1 controls.
In August of 2005 Wisconsin’s Hybrid Team returned to Ballard Power Systems for a final checkup. After several hours of testing and diagnosis, the EV1 was given a clean bill of health. Since then, it has operated flawlessly providing invaluable data to the Wisconsin Hybrid Team while educating our next generation engineers. The EV1 project is another example of the dedication and creativity of the young engineer’s mind. This small group of undergraduate students has and will continue to make important contributions to the advancement of personal mobility.