Publications

Ivanović, V., "Identification and control of SI engine in idle speed operating mode", Bachelor's thesis, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia, May 2003.

Abstract. The thesis deals with idle speed control of a spark-ignition (SI) engine with electronic throttle control (ETC) included. For the purpose of theoretical analysis, a nonlinear engine model with throttle angle and spark timing as input variables is adopted. The nonlinear engine model is then linearized, in order to facilitate its analysis and engine control system design. A possibility of simplification of linearized engine model is analyzed.

The model of a 10-kW SI engine model has been experimentally identified. Two identification procedures have been considered. The first one is based on recording the engine static maps using an engine dynamometer, and based on the knowledge of physical parameters such as the manifold volume and the engine displacement. The second identification procedure is based on the least-squares identification method, which is used to identify the parameters of a general linearized engine model of an arbitrary order.

The SI engine idle speed control is firstly considered theoretically. The damping optimum method is used as a basis for design of various types of controllers: PI and PID engine speed controllers with or without spark timing control. The design is based on a simplified linearized engine model for the given idles speed control operating range. A comparative analysis of the closed-loop control system behavior with various controllers is carried out by computer simulation. An analysis of the control system robustness with respect to engine model parameter variations is conducted as well.

For the purpose of experimental verification of the idle speed controller, the aforementioned design procedure is used for designing a PI idle speed controller of the 10-kW engine. The controller is extended with a feedforward compensator of the measurable load torque, in order to improve the control system performance. Also, a cruise control system with the PI engine speed controller has been considered and experimentally examined. All the control and identification algorithms have been implemented in C programming language on a Pentium III-based PC.