Optimal control of a small hybrid car

Overview & Synopsis

The stringent fuel consumption and pollutants reduction standards enforce manufacturers and carmakers to have a closer look on new powertrain architectures for passenger cars. In that context, studies on hybrid vehicles appear today in a substantial scale. The association of a high efficiency electrical motor with an internal combustion engine needs specific control laws in order to optimize the energy transfer management. This paper presents a new control strategy developed by SiemensVDO Automotive and the LEEI laboratory on an small and mild hybrid vehicles. A supervisor with the full control of the drive train (clutch, gearshifts, thermal IC engine torque and electrical motor torque) allows to improve fuel consumption and to maintain an admissible battery state of charge. It also provides the optimal gear ratio that can be applied according to acceleration constrains. This includes the concept of driveability in the criterion that is often in contradiction with energy savings.