The Ohio State EcoCAR 2 engineering team has been hard at work designing the vehicle’s mechanical, electrical and control systems.
The mechanical team has been figuring out how to package all the powertrain components in the vehicle and then create mounting brackets for them. One of the biggest challenges the team faces on the front powertrain is packaging the engine, the clutch between the engine and transmission, the front electric machine, the inverter and the 6-speed transmission in such a way that it fits within the width of the engine bay. Additionally the team has to make multiple adapter shafts for the front powertrain components, since each of the components has a different type of input shaft. As they found out over the past few months, every half inch of space they can save by selecting more compact components helps a lot!
On the rear powertrain, the mechanical team needs to find a way to mount the rear electric machine and single speed gearbox to the rear cradle they will be placing inside the Malibu. To complicate the rear powertrain problem even more, they also need to place an 18.9kW-hr battery pack in the trunk of the Malibu and the rear electric machine’s inverter, while still maintaining at least seven cubic feet of cargo space. Over the past several months the team probably went through at least 10 different configurations of the battery pack and rear powertrain components before finding one that worked.
The controls team also kept busy designing code for the team programmed controllers and setting up a dSPACE Hardware-in-the-Loop (HIL) system. For the EcoCAR 2 competition, the team decided to program its own engine controller, transmission controller and vehicle supervisory controller. Since they didn’t have their vehicle yet, the team created code for these three controllers and tested it on HIL equipment. The HIL equipment is essentially a powerful computer equipped with I/O boards that is capable of running a hybrid vehicle model in real time.
The HIL’s I/O boards are used to connect the three team-programmed controllers to the hybrid vehicle model through Controller Area Networks (CAN). The I/O boards are very useful because they allow the team to connect a variety of actuators to the HIL equipment, so they can make sure the code can move the actuators correctly. The team also set up its 6-speed transmission, its actuators and the transmission controller with the HIL equipment so that they could create the basic shift logic for the transmission before getting the Malibu this summer!