Optimal Slip Control of a Torque Converter Clutch

Abstract

Slip control of a torque converter clutch (TCC) has been developed for years but most approaches are focused on time-based methods without offering a systematic approach for dealing with the time-varying signals associated with the engine torque pulsation. As one of the major vibration sources of a vehicle, engine torque is periodic in the crankshaft rotational angle but aperiodic in time as the engine speed changes in real-time. This paper first presents a powertrain vibration analysis based on the transient engine torque input and the conventional TCC slip control. Simulation results show that the conventional time-based TCC slip control does not settle the periodic nature of the engine torque vibration with respect to crankshaft angle. However, a time-varying angle-based control method can solve this issue. The paper then proposes an optimal TCC torque trajectory by using dynamic programming for this time-varying angle-based control method. Simulation results demonstrate the energy saving potential of the optimal trajectory over the conventional method.