Control system development for a pre-transmission parallel plug-in hybrid electric vehicle powertrain with a mechanical continuously variable transmission

Plug-In hybrid electric automobiles show great promise for shifting the United States transportation sector away from petroleum dependence and towards energy sustainability through renewable electricity and bio fuels. The Trinity study at UC Davis was designed to develop and demonstrate the technology required for widespread adoption of plug in hybrid electric vehicles. This thesis presents the vehicle system architecture and the controls development methodologies implemented in the Trinity system. The Trinity system was implemented into a 2005 Chevrolet Equinox. The powertrain system consists of a pre-transmission parallel hybrid architecture with a large enough battery pack and powerful electric motors to propel the vehicle through normal driving over extended distances. The large battery and electric drive system enables the driver to avoid consuming liquid fuel for daily driving by replacing it with electricity, while allowing the flexibility to have unlimited driving range whenever liquid fuel is available. The performance of the vehicle was measured to have a 29.3 mile all electric range over the UDDS driving cycle and real world charge sustaining fuel economy of 29.1 city and 34.0 highway miles per gallon. The weight of the test vehicle was 5081 pounds with occupants and data acquisition equipment. The conventional Equinox curb weight is 3660 pounds. Despite the weight increase, the modified vehicle shows significantly improved fuel economy in the charge sustaining mode. Additionally, the modified Equinox has an electric driving range of 30 miles. This feature would allow over half of US drivers to avoid using gasoline for daily commuting. In mass production, this type of vehicle has the potential to displace a large percentage of the liquid fuel used for transportation.