Das Gaswechselsystem moderner Dieselmotoren und dessen Regelung müssen zunehmend höheren Anforderungen genügen, um die Rohemissionen im Hinblick auf kommende Abgasgesetzgebungen in den Hauptmärkten weiter zu reduzieren, den Drehmomentverlauf und die Dynamik über den gesamten Drehzahlbereich zu verbessern, sowie um Abgasnachbehandlungssysteme zu unterstützen. Die Einführung der physikalisch-modellbasierten Regelung des Luftpfads ermöglicht es, die Kennfeldstrukturen stark zu vereinfachen, sich ändernde Betriebsbedingungen genauer zu berücksichtigen sowie die Linearisierung, Störgrößenkom-pensation und Entkopplung von Regelkreisen. The gas exchange system of modern diesel engines and its control has to fulfill increasingly challenging requirements in order to further reduce raw emissions with regard to the next legislations in the main markets, improve torque and dynamic response over the whole speed range and to support exhaust aftertreatment systems. The introduction of the physical model based control of the airpath gives the possibility to reduce lookup table structures, to adjust to changing operation conditions as well as linearization, disturbance compensation and decoupling of control loops.

This paper proposes model reduction techniques for reducing engine airpath models in real-time (RT), for a control oriented application in an engine equipped with high pressure exhaust gas recirculation (EGR-HP) and single stage turbocharger. There are two major challenges addressed by authors: First, reducing the order without compromising the performance in terms of accuracy by decoupling the nonlinear coupled differential equations of airpath system in-order to use them in real-time processor-in-loop control application. A model reduction technique based on different dynamic characteristics between thermodynamic states followed by semi-implicit Euler (SIE) numerical method to solve coupled dynamic multi-input multi-output (MIMO) differential equation models is demonstrated. Second, the authors have proposed a novel method to calculate gas mass flow via compressor, coupled with engine airpath model in real-time. The proposed models of airpath system coupled with turbocharger models for a diesel engine is validated with experimental data to evaluate performance of pressures, temperatures, mass flows at relevant components. The developed airpath model is used for calculating thermodynamic properties in real-time for state of art engine control unit (ECU) in production engine and become basis for feedforward as well as closed loop control of airpath variables for real-time system. Authors further propose to use this modeling approach for calculating airpath system variables for exhaust aftertreatment system, injection system, and for virtualization of sensor values in airpath systems.

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