Idle speed control system design based on engine torque management

In this paper, a physics/map-based spark ignition (SI) engine model is deduced for controller design, consisting of air-path model and engine speed model. Based on this model, an idle speed control system is designed based on model inverse-dynamics in the framework of engine torque management system. Firstly, the desired engine idle speed is transformed into the desired engine combustion torque using the inverse-dynamic of engine speed model. Secondly, the desired engine combustion torque is transformed into the desired airflow entering the cylinder using a map. Finally, the desired airflow is transformed into the desired throttle angle by using the inverse-dynamics of air-path model. Then, the engine idle speed is achieved by tracking the desired throttle angle. The simulation results are provided to demonstrate the effectiveness of the proposed control system.