Model Based Control of SCR Dosing and OBD Strategies with Feedback from NH3 Sensors

This paper presents a model-based control system for SCR urea dosing employing an embedded real-time SCR chemistry model and a NH3 sensor. The control algorithm consists of a number of control features designed to enhance ammonia storage control and closed-loop compensation using the mid-brick NH3 s...

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Bibliographic Details
Published in:SAE International Journal of Fuels and Lubricants 2009-01, Vol.2 (1), p.375-385
Main Authors: Herman, Andrew, Wu, Ming-Cheng, Cabush, David, Shost, Mark
Format: Article
Language:English
Subjects:
Adaptive algorithms
Adaptive control
Aging
Algorithms
Ammonia
Catalysts
Control algorithms
Control systems
Control theory
Dosage
Emission analysis
Emissions
Feedback
Feedback control
Floating point arithmetic
Robust control
Sensors
Urea
Ureas
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Summary:This paper presents a model-based control system for SCR urea dosing employing an embedded real-time SCR chemistry model and a NH3 sensor. The control algorithm consists of a number of control features designed to enhance ammonia storage control and closed-loop compensation using the mid-brick NH3 sensor. An adaptive control algorithm is developed to demonstrate robustness of the feedback control system to compensate for catalyst aging, urea injection malfunction, or dosing fluid concentration variation. Simulation and engine dynamometer testing following ESC and FTP emission cycles are used to demonstrate the advantages of this control approach for meeting both NOx emission requirements and NH3 slip targets. Furthermore this paper demonstrates potential of a NH3 sensor for on-board diagnostics. Additionally the feasibility of implementing model based algorithms in a 32-bit floating-point environment with an automotive controller is examined.
ISSN:1946-3952
1946-3960
DOI:10.4271/2009-01-0911