Modelling, Analysis, Control and Experimental Validation of Electromechanical Valve Actuators in Automotive Systems

Abstract

This Thesis is concerned with the modelling, analysis and control of novel mechatronic valve actuators for automotive systems, specifically, the control of the mechanical valves to intake and exhaust gases in Internal Combustion Engines (ICE). Scientific studies have shown that significant benefits in terms of engine efficiency and emissions can be obtained through the adoption of variable valve actuation. Current engine technology are based on the use of a mechanical driven camshaft, which is a no flexible device due to its strongly coupling to crankshaft position. Thus, it is not possible to adjust or adapt in real time the valve features according to the engine working conditions. Hence, there is the need of designing innovative mechanisms to actuate the engine valves. In so doing, traditional mechanical cam systems can be removed and a train of single actuated valves is incorporated into the ICE, leading to the development of camless engine technology. Electro-Mechanical Valve Actuators (EMVA) have been considered as one of the most promising technological solutions to develop this novel engine technology. To achieve all the potential benefits of the EMVA systems, two crucial control problems have to be tackled and solved efficiently: the control of the first lift manoeuvre, known as First Catching Control (FCC) problem, and the control of the valve seating velocity, known as Soft Landing Control (SLC) problem. The thesis shows that the analysis and control of the EMVA device can be successfully addressed in the framework of non-smooth dynamical system and nonlinear control theory, furthermore, the tuning of non linear controllers can be successfully done by using closed loop bifurcation diagram analysis. In particular, a non-smooth mathematical model is proposed, estimated and validated experimentally. A novel Key-on controller is proposed to solve the FCC control problem, while a combined feedforward-sliding mode controller is proposed to solve the SLC control problem. The proposed control approaches have been tested numerically and validated on an experimental setup, leading to successful results.