Test Bench Results of a Torque Pedal Interpretation with a CVT-Equipped Power Train

This paper presents the implementation of a torque pedal interpretation scheme in the CVT-equipped hybrid car which is currently being developed at the Swiss Federal Institute of Technology (ETH) as project Hybrid III. At partial load, a duty cycle operation mode is used in order to increase fuel efficiency. A flywheel is used to store excess power of the combustion engine as well as when the speed of the vehicle is decreased, recuperating the energy for reacceleration. A third mode, called highway operation, is used whenever the demanded power at the wheel exceeds a certain limit. A hierarchical controller scheme is implemented to maintain a comparable behavior of the vehicle in all operation modes.

Beyond simulations, this controller operates successfully under real time conditions on the dynamic test bench. Test cycles with a human driver have successfully proven the effectiveness of the chosen set of controllers. The fuel consumption resulting from the test bench cycles is measured and compared with that calculated in simulated cycles. Measurements of the same cycles with conventional cars are discussed briefly as well.