Holistic Diesel Engine and Exhaust After-Treatment Model Predictive Control

摘要

Today’s and future more stringent Diesel on-road emission regulations requires low emissions during normal operation with fewer exceptions. This together with the demand for low fuel consumption resulting that the control strategy must be able to fulfill both objectives simultaneously. In this work we present a holistic engine and Exhaust After-Treatment System (EATS) control which robustly fulfill the emission legislation together with optimal fuel consumption. With traditional PID control schemes it is typically non intuitive how to create a holistic controller that obtain both these objectives. The proposed holistic scheme is based on Model Predictive Control (MPC) framework in an intuitive straight forward way. The EATS system used in this paper does not include any external heating device and the SCR system was setup to always target NH3storage levels to secure high NOxconversion efficiency. The holistic MPC controller is therefore setup to control the engine out NOxand temperature to meet the EATS demands. The holistic MPC controls the gas exchange actuators, while the injection strategy is controlled with a traditional map-based structure. The designed controller is integrated in a production Engine Electrical Control Unit (EECU) and tests are performed in engine test bench. The engine used in this work is a Heavy Duty 13L Diesel engine with turbo compound as a waste heat recovery device. The results show that using the proposed holistic MPC scheme the controller can be on a high level intuitively tuned to fulfill the emissions robustness while maintaining low fuel consumption in on-road cycles.