Control of variable geometry turbocharged diesel engines for reduced emissions

The emission control problem for an automotive direct injected compression ignition (diesel) engine equipped with exhaust gas recirculation (EGR) and a variable geometry turbocharger (VGT) is considered. The objective is to operate the engine to meet driver´s torque demand and minimize NO_x emissions while at the same time avoiding visible smoke generation. It is demonstrated that the steady-state optimization of engine emissions results in operating points where EGR and VGT actuators are in effect redundant in their effect on the variables that most directly affect the emissions. A multivariable feedback controller is proposed which accounts for this actuator redundancy. Furthermore, it coordinates the two actuators to fully utilize their joint effect on engine emission performance. Experimental results confirm good response properties of the proposed controller