Control oriented modeling of dynamic torque converter system

A torque converter is an essential part of an automatic transmission. It is a hydrodynamic device that has most influence on the transient response of a vehicle such as gear shifting and vehicle launching. In order to study such characteristics accurately, dynamic analysis of the torque converter is necessary. The zero order torque converter model of Kotwicki has been widely used for control design purposes, since the dynamic modeling method has not been readily available to control engineers. A dynamic model for the stand-alone torque converter system that allows mathematical analysis and performance prediction for transient powertrain controls based on four-first order nonlinear differential equations is presented. The results confirm that the model predicts hydrodynamic torque converter dynamic response accurately, the prediction being robust to variation of the operating condition.