Abstract
Keywords - Air management control, cascade control, actuators non-linearities, actuators coupling, Diesel engine control.
Abstract - A key issue for compliance with future pollutant emission regulations in variable geometry turbocharged diesel engines is the achievement of a precise control of the air management process, particularly air mass flow ( mª ) and intake manifold pressure (Pª ).
For a good identification and building of a model-based control (such as Generalized Predictive Control - GPC) of the air management process is fundamental to obtain a good characterization and control of the actuators of the process: exhaust gas recirculation (EGR) valve and variable geometry turbine valve (VGT).
In this paper, the characterization of the EGR and VGT non-linearities is discussed (specifically, saturations and hysteresis that vary according to the engine speed). Appropriate position controls are designed for these valves to form a first control layer (internal loop) with the objective of achieving an adjusted main control. The benefits of including this internal loop as part of a cascade control structure, where the main loop regulates Pª and mª , are evaluated.
Results used for the characterization of the valves in different operating points of the engine are shown. This work also shows the experimental results of the controls developed for the basic layer, and compares them with the system without an internal loop.