This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Extended Kalman Filter Estimator for NH 3 Storage, NO, NO 2 and NH 3 Estimation in a SCR
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 08, 2013 by SAE International in United States
Annotation ability available
This paper focuses on the development of an Extended Kalman Filter for estimating internal species concentration and storage states of an SCR using NOX and NH₃ sensors. The motivation for this work was twofold. First, knowledge of internal states may be useful for onboard diagnostic strategy development. In particular, significant errors between the outlet NOX or NH₃ sensors, reconstructed from estimated states, and the measured NOX or NH₃ concentrations may aid OBD strategies that attempt to identify particular system failure modes. Second, the EKF described estimates not only stored ammonia but also NO, NO₂ and NH₃ gas concentrations within and exiting the SCR. Exploiting knowledge of the individual species concentrations, instead of lumping them together as NOX, can yield improved closed loop urea controller performance in terms of reduced urea consumption and better NOX conversion.
The model used for EKF development was calibrated to transient engine data using a 2010 Cummins ISB engine with a production aftertreatment system consisting of a DOC, CPF and SCR. The EKF was then exercised for three different SCR outlets, sensor configurations: NOX only, NH₃ only and both NOX and NH₃. The EKF-estimated outlet NO, NO₂, and NH₃ concentrations were compared to measured experimental data using a mass spectrometer. Not surprisingly, the case where both NOX and NH₃ were measured at the SCR outlet and used as input to the EKF yielded the best results. The next best performance was achieved using only the NH₃ sensor. This was likely due to a better estimate of the NH₃ storage within the SCR and thus better estimates of the effect of the reactions. The results of the NOX sensor only case might be improved by using a better model of the NOX sensor.
CitationSurenahalli, H., Parker, G., and Johnson, J., "Extended Kalman Filter Estimator for NH3 Storage, NO, NO2 and NH3 Estimation in a SCR," SAE Technical Paper 2013-01-1581, 2013, https://doi.org/10.4271/2013-01-1581.
- Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles https://federalregister.gov/a/2011-20740 August 2011
- Devarakonda , M. , Parker , G. , Johnson , J. , Strots , V. et al. Model-Based Estimation and Control System Development in a Urea-SCR Aftertreatment System SAE Int. J. Fuels Lubr. 1 1 646 661 2009 10.4271/2008-01-1324
- Devarakonda , M. , Parker , G. , Johnson , J. NOx control systems and methods for controlling NOx emissions U.S. Patent 2012/0260634 A1 October 18 2012
- Na , H. , Reed , D. , Annaswamy , A. , Laing , P. et al. Control-oriented Reduced-order Models for Urea Selective Catalytic Reduction Systems Using a Physics-based Approach SAE Technical Paper 2011-01-1326 2011 10.4271/2011-01-1326
- Hsieh Ming Feng and Wang Junmin An Extended Kalman Filter for Ammonia Coverage Ratio and Capacity Estimations in the Application of Diesel Engine SCR Control and Onboard Diagnosis American Control Conference Marriott Waterfront Baltimore, MD, USA 2010
- Hsieh Ming Feng and Wang Junmin An Extended Kalman Filter for NOx Sensor Cross Sensitivity Elimination in Selective Catalytic Reduction Applications American Control Conference Marriott Waterfront Baltimore, MD, USA 2010
- Hsieh Ming-Feng Control of Diesel Engine Urea Selective Catalytic Reduction Systems The Ohio State University PhD Dissertation 2010
- Song , X. , Naber , J. , Johnson , J. , and Parker , G. An Experimental and Modeling Study of Reaction Kinetics for a Cu-Zeolite SCR Catalyst Based on Engine Experiments SAE Technical Paper 2013-01-1054 2013
- Simon Dan Optimal State Estimation: Kalman, H Infinity, and Nonlinear Approaches John Wiley and Sons 2006
- Peyton Jones , J. and Geveci , M. Smart Sensing and Decomposition of NO x and NH 3 Components from Production NO x Sensor Signals SAE Int. J. Engines 4 1 1393 1401 2011 10.4271/2011-01-1157