Model-based fault detection and diagnosis of selective catalytic reduction systems for diesel engines

The continuously stringent emission regulations call for the adaptation of the Selective Catalytic Reduction (SCR) system by many diesel manufacturers. In order to show the EPA the latest emission compliance, the sensors are required to be installed at upstream and downstream of the SCR. As a result, the reduction efficiency is also required to be monitored by the On-Board Diagnostics (OBD) regulations. Specifically, a diagnostic algorithm is required to detect and isolate the SCR system faults that may cause emission violation. In this research, two model-based fault detection and isolation algorithms are developed to detect and isolate the dosing fault and the outlet NOx sensor fault for the SCR system. The dosing fault is treated as an actuator additive fault, while the outlet NOx sensor drift and/or offset fault is treated as a sensor additive fault. First, a 0-D SCR nonlinear dynamic model was developed to facilitate the model-based approaches. A parity equation residual generator was designed based on the linearized SCR model and the fault transfer function matrix. Then, a sliding mode observer based residual generator is designed directly based on the nonlinear model. The two diagnostic algorithms are then implemented in the Matlab/Simulink environment for validation. A high fidelity nonlinear 1-D SCR model is used to generate system outputs and to simulate the plant. The simulation results show that the two model-based fault diagnosis approaches are capable of detecting and isolating the outlet NOx sensor and dosing faults in real time.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Agricultural & Biological Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Chen, Rui

Contributors dc:contributor

• Wang, Xinlei
• Hansen, Alan C.
• Lee, Chia-Fon
• Domínguez-García, Alejandro D.

• Diesel
• Selective Catalytic Reduction (SCR)
• Nitrogen Oxides (NOx)
• diagnosis
• On-Board Diagnostics (OBD)

Statement dc:rights

• Copyright 2014 Rui Chen

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/50387

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/50387