Title
An OBD strategy to estimate SCR ageing and detect urea injection faults
Author
Mora, J.
Willems, F.P.T.
Seykens, X.L.J.
Guardiola, C.
Publication year
2018
Abstract
The most recent regulation for diesel engines with regards to NOx emissions and SCR systems considers stringent OBD requirements. In this paper, an observer of the ageing state is developed considering NO, NO2 and NH3 concentrations, the surface coverage ratio θNH3, and the ammonia storage capacity Ω as states. The observer is based on an extended Kalman filter and the SCR downstream NOx and NH3 measurements. Accuracy and convergence time are presented for the observer validation in simulation in a dynamic WHTC at warm starting conditions. As the ageing state estimation is based on the residual between a model and measurements, an additional indicator avoids associating an error inherent of urea injection faults to ageing. The performance of this indicator is independent from the ageing state of the SCR. The highly detailed, physics-based 1D SIMCAT model is used as the SCR plant for the ageing estimation and as the model to track the urea injected quality. Then, a control-oriented model is also used in simulation to allow the state-space representation required for the observer. Accuracy of both models is argued, showing the limitations and advantages of the control-oriented model. © 2018
Subject
Diagnostics
Engine control
Engine exhaust gas aftertreatment
Ammonia
Diesel engines
Exhaust gases
Exhaust systems (engine)
Kalman filters
Nitrogen oxides
Plasma diagnostics
State space methods
Urea
After-treatment
Control oriented models
Convergence time
Engine control
Modeling and measurement
State space representation
Storage capacity
Surface coverages
Metabolism
To reference this document use:
http://resolver.tudelft.nl/uuid:74523860-2e28-45ec-9046-89b9bda2f6fa
TNO identifier
843760
Publisher
Elsevier B.V.
ISSN
2405-8963
Source
IFAC-PapersOnLine, 51 (31), 369-376
Document type
article