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The regulation of NOx emission from a diesel engine is becoming stricter by the environmental agency and furthermore, EGR has been adopted to reduce NOx emission. Air flow control of a diesel engine combined with turbocharger and EGR is complicated because turbocharger and EGR are coupled physically. This paper examines the design of a model based control structure for diesel engine with a turbocharger and EGR. Model based control provides desirable control strategies from the physical analysis of an engine model. Air fraction and exhaust manifold pressure target based control simulation was conducted in this research. Engine is highly nonlinear and susceptible to uncertainties. To overcome this problem, a robust controller was designed by using a sliding mode control method.

This paper deals with the simplification and optimization methods in diesel engine control which is based on the air management system model of 1stage VTG and HP-EGR. Especially, simplified model based controller is suggested including more tracking performance of target values for comparison from previous multivariable sliding mode controller with intake and exhaust manifold output set. Moreover, in calculating desired exhaust manifold pressure, the simple process which only use target flow rates is suggested. There are fewer errors than general process's which have to add the target state process including the turbocharger parameter errors. Model based controller has assumption that mathematical model has to be very accurate, therefore, has to reflect the physical engine properties in every operating point. But, it is hard to satisfy this assumption because of the modeling uncertainties in mathematical point and a variety of environmental factor in real engine.