Model based burnt gas fraction control of Turbocharged Diesel Engine with Dual loop EGR system

Abstract

In accordance with strengthening regulation of NOx and PM emission in diesel engine, EGR system has been adopted to control engine combustion. Recently, EGR system has been expanded into dual loop EGR system to increase EGR rate as well as utilize exhaust gas strategically. In aspects of engine combustion characteristics, burnt gas fraction is becoming important factor to solve NOx and PM emission reduction problem efficiently. This paper describes a model based burnt gas fraction control structure for diesel engine with dual loop EGR and turbocharger. The model based control is worthy of a research because it helps precise control of diesel engine air management system especially in transient states, by considering coupled behavior within the system. For the controller validation, turbocharged diesel engine with dual loop EGR system modeling was conducted first in this research. Then, control oriented reduced order model of diesel engine air management system is established to simplify control input computation. Using sliding mode control method, model based burnt gas fraction controller was designed and controller robustness at some operating points was validated through several approaches.