0
Research Papers

An NOx Sensor-Based Direct Algebraic Approach-Newton Observer for Urea Selective Catalytic Reduction System State Estimations

[+] Author and Article Information
Qinghua Lin

Department of Mechanical Engineering,
Tennessee Technological University,
Cookeville, TN 38505

Pingen Chen

Department of Mechanical Engineering,
Tennessee Technological University,
Cookeville, TN 38505
e-mail: pchen@tntech.edu

1Corresponding author.

Contributed by the Dynamic Systems Division of ASME for publication in the JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT,AND CONTROL. Manuscript received November 18, 2017; final manuscript received May 4, 2018; published online June 4, 2018. Assoc. Editor: Mahdi Shahbakhti.

J. Dyn. Sys., Meas., Control 140(11), 111004 (Jun 04, 2018) (8 pages) Paper No: DS-17-1572; doi: 10.1115/1.4040221 History: Received November 18, 2017; Revised May 04, 2018

NOx sensor-based state estimations for urea-based selective catalytic reduction (SCR) systems have attracted much attention in the past several years because of their significant importance in achieving high NOx conversion efficiency and low ammonia slip at low operation cost. Most of the existing SCR state estimation techniques require sophisticated design processes and significant tuning efforts, which may prevent them from widespread applications to production urea-SCR systems. In addition, the existing SCR state observers may not be able to achieve fast and accurate estimations due to the corresponding slow estimation error dynamics. The purpose of this study was to design a straightforward and effective NOx sensor-based SCR state estimation algorithm for decoupling post-SCR NOx sensor signals (NOx concentration, ammonia concentration), and for estimating ammonia coverage ratio of the urea-SCR systems. A singular-perturbation-based approach was applied to attain the reduced-order SCR model by decoupling the fast NO and NH3 concentration dynamic models from the slow ammonia coverage ratio dynamics model. Based on the reduced-order model, a direct algebraic approach (DAA)-Newton observer was proposed for estimating ammonia coverage ratio. The achieved ammonia coverage ratio estimation was applied to estimate the post-SCR NOx and NH3 concentrations. Simulation verification results under US06 cycle proved the effectiveness of the proposed method in accurately estimating the aforementioned key SCR states. The proposed observer can potentially be popularly applied to the production SCR systems for the advanced SCR control systems and on-board diagnostics.

FIGURES IN THIS ARTICLE
<>
Copyright © 2018 by ASME
Your Session has timed out. Please sign back in to continue.

References

Koebel, M. , Elsener, M. , and Kleemann, M. , 2000, “ Urea-SCR: A Promising Technique to Reduce NOx Emissions From Automotive Diesel Engines,” Catal. Today, 59(3–4), pp. 335–345. [CrossRef]
Hsieh, M. , and Wang, J. , 2011, “ Development and Experimental Studies of a Control-Oriented SCR Model for a Two-Catalyst Urea-SCR System,” Control Eng. Pract., 19(4), pp. 409–422. [CrossRef]
Tronconi, E. , Nova, I. , and Ciardelli, C. , 2005, “ Modelling of an SCR Catalytic Converter for Diesel Exhaust After Treatment: Dynamic Effects at Low Temperature,” Catal. Today, 105(3–4), pp. 529–536. [CrossRef]
Devarakonda, M. , Parker, G. , and Johnson, J. H. , 2009, “ Model-Based Estimation and Control System Development in a Urea-SCR After Treatment System,” SAE Int. J. Fuels Lubr., 1(1), pp. 646–661. [CrossRef]
Hsieh, M. , and Wang, J. , 2011, “ A Two-Cell Backstepping-Based Control Strategy for Diesel Engine Selective Catalytic Reduction Systems,” IEEE Trans. Control Syst. Technol., 19(6), pp. 1504–1515. [CrossRef]
Herman, A. , Wu, M. , and Cabush, D. , 2009, “ Model-Based Control of SCR Dosing and OBD Strategies With Feedback From NH3 Sensors,” SAE Int. J. Fuels Lubr., 2(1), pp. 375–385. [CrossRef]
Hsieh, M. , and Wang, J. , 2012, “ Adaptive and Efficient Ammonia Storage Distribution Control for a Two-Catalyst Selective Catalytic Reduction System,” ASME J. Dyn. Syst. Meas. Control, 134(1), p. 011012. [CrossRef]
Chen, P. , and Wang, J. , 2013, “ Integrated Diesel Engine and Selective Catalytic Reduction System Active NOx Control for Fuel Economy Improvement,” American Control Conference (ACC), Washington, DC, June 17–19, pp. 2196–2201.
Chen, P. , and Wang, J. , 2015, “ Coordinated Active Thermal Management and Selective Catalytic Reduction Control for Simultaneous Fuel Economy Improvement and Emissions Reduction During Low-Temperature Operations,” ASME J. Dyn. Syst. Meas. Control, 137(12), p. 121001. [CrossRef]
Seher, D. H. , Reichelt, M. , and Wickert, S. , 2003, “ Control Strategy for NOx-Emission Reduction With SCR,” SAE Trans., 112(2), pp. 67–71.
Inagaki, H. , Oshima, T. , and Miyata, S. , 1998, “ NOx Meter Utilizing ZroD 2 Pumping Cell,” SAE Paper No. 980266.
Kunimoto, A. , Hasei, M. , and Yan, Y. , 1999, “ New Total-NOx Sensor Based on Mixed Potential for Automobiles,” SAE Paper No. 1999-01-1280.
Hsieh, M. , and Wang, J. , 2011, “ Design and Experimental Validation of an Extended Kalman Filter-Based NOx Concentration Estimator in Selective Catalytic Reduction System Applications,” Control Eng. Pract., 19(4), pp. 346–353. [CrossRef]
Zhang, H. , Wang, J. , and Wang, Y. , 2013, “ Robust Filtering for Ammonia Coverage Estimation in Diesel Engine Selective Catalytic Reduction Systems,” ASME J. Dyn. Syst. Meas. Control, 135(6), p. 064504. [CrossRef]
Bonfils, A. , Creff, Y. , and Lepreux, O. , 2014, “ Closed-Loop Control of a SCR System Using a NOx Sensor Cross-Sensitive to NH3,” J. Process Control, 24(2), pp. 368–378. [CrossRef]
Upadhyay, D. , and Van Nieuwstadt, M. , 2013, “ Robust Separation of Signal Domain From Single Channel Mixed Signal Output of Automotive Urea Based Selective Catalytic Reduction Systems,” ASME J. Dyn. Syst. Meas. Control, 136(1), p. 011012. [CrossRef]
Chen, P. , and Wang, J. , 2015, “ Sliding-Mode Observers for Urea Selective Catalytic Reduction System State Estimations Based on Nitrogen Oxide Sensor Measurements,” Proc. Inst. Mech. Eng., Part D, 229(7), pp. 835–849. [CrossRef]
Zhang, H. , Wang, J. , and Wang, Y. , 2015, “ Nonlinear Observer Design of Diesel Engine Selective Catalytic Reduction Systems With NOx Sensor Measurements,” IEEE/ASME Trans. Mechatronics, 20(4), pp. 1585–1594. [CrossRef]
Lin, Q. , and Chen, P. , 2017, “ A Simple and Effective Methodology for Estimating Urea Selective Catalytic Reduction Systems States Based on NOx Sensor Measurement,” American Control Conference (ACC), Seattle, WA, May 24–26, pp. 5367–5372.
Chen, P. , and Wang, J. , 2015, “ Nonlinear Model Predictive Control of Integrated Diesel Engine and Selective Catalytic Reduction System for Simultaneous Fuel Economy Improvement and Emissions Reduction,” ASME J. Dyn. Syst. Meas. Control, 137(8), p. 081008. [CrossRef]
Schär, C. , Onder, C. H. , and Geering, H. P. , 2006, “ Control of an SCR Catalytic Converter System for a Mobile Heavy-Duty Application,” IEEE Trans. Control Syst. Technol., 14(4), pp. 641–653. [CrossRef]
Devarakonda, M. , Parker, G. , and Johnson, J. H. , 2008, “ Adequacy of Reduced Order Models for Model-Based Control in a Urea-SCR Aftertreatment System,” SAE Paper No. 2008-01-0617.
Ericson, C. , Westerberg, B. , and Odenbrand, I. , 2008, “ A State-Space Simplified SCR Catalyst Model for Real Time Applications,” SAE Paper No. 2008-01-0616.
Guzzella, L. , and Onder, C. H. , 2010, Introduction to Modeling and Control of Internal Combustion Engine Systems, Springer, Berlin, p. 354. [CrossRef]
Chi, J. N. , and DaCosta, H. F. , 2005, “ Modeling and Control of a Urea-SCR Aftertreatment System,” SAE Trans., 114(4), pp. 449–464.
Hsieh, M. , and Wang, J. , 2011, “ NO and NO2 Concentration Modeling and Observer-Based Estimation Across a Diesel Engine Aftertreatment System,” ASME J. Dyn. Syst. Meas. Control, 133(4), p. 041005. [CrossRef]
Chen, P. , and Wang, J. , 2016, “ Estimation and Adaptive Nonlinear Model Predictive Control of Selective Catalytic Reduction Systems in Automotive Applications,” J. Process Control, 40, pp. 78–92. [CrossRef]
Song, Q. , and Zhu, G. , 2002, “ Model-Based Closed-Loop Control of Urea SCR Exhaust Aftertreatment System for Diesel Engine,” SAE Paper No. 2002-01-0287.
Wang, D. , Yao, S. , Shost, M. , Yoo, J.-H. , Cabush, D. , Racine, D. , Cloudt, R. , and Willems, F. , 2008, “ Ammonia Sensor for Closed-Loop SCR Control,” SAE Int. J. Passeng. Cars - Electron. Electr. Syst., 1(1), pp. 323–333.
Frobert, A. , Raux, S. , and Creff, Y. , 2013, “ About Cross-Sensitivities of NOx Sensors in SCR Operation,” SAE Paper No. 2013-01-1512.
Devarakonda, M. , Parker, G. , and Johnson, J. H. , 2009, “ Model-Based Control System Design in a Urea-SCR Aftertreatment System Based on NH3 Sensor Feedback,” Int. J. Autom. Technol., 10(6), pp. 653–662. [CrossRef]
Babaali, M. , Egerstedt, M. , and Kamen, E. W. , 2003, “ An Observer for Linear Systems With Randomly-Switching Measurement Equations,” American Control Conference (ACC), Denver, CO, June 4–6, pp. 1879–1884.
Babaali, M. , Egerstedt, M. , and Kamen, E. W. , 2004, “ A Direct Algebraic Approach to Observer Design Under Switching Measurement Equations,” IEEE Trans. Autom. Control, 49(11), pp. 2044–2049. [CrossRef]
Chen, P. , and Wang, J. , 2014, “ Control-Oriented Model for Integrated Diesel Engine and Aftertreatment Systems Thermal Management,” Control Eng. Pract., 22 pp. 81–93. [CrossRef]
Chen, P. , and Wang, J. , 2013, “ Observer-Based Estimation of Air-Fractions for a Diesel Engine Coupled With Aftertreatment Systems,” IEEE Trans. Control Syst. Technol., 21(6), pp. 2239–2250. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Low-cost sensor setup for production SCR systems

Grahic Jump Location
Fig. 3

Exhaust flow rate, exhaust gas temperature, and O2 concentrations during US06 cycle

Grahic Jump Location
Fig. 4

Pre-SCR NOx and NH3 concentrations during US06 cycle

Grahic Jump Location
Fig. 2

Correlation between SCR-out NO and NH3 concentrations (exhaust conditions: CNH3,in= 0.01 mole/m3, CNO,in= 0.009 mole/m3, T = 570 K, F = 0.21 m3/s, CO2,in = 2.0 mole/m3, CNOx,sen = 0.0013 mole/m3)

Grahic Jump Location
Fig. 7

Estimation of post-SCR NOx concentration during US06 cycle

Grahic Jump Location
Fig. 8

Zoom-in of Fig. 7 during the time interval from 0 to 10th second

Grahic Jump Location
Fig. 9

Zoom-in of Fig. 7 at time interval from 200th to 340th second

Grahic Jump Location
Fig. 10

Estimation of post-SCR NH3 concentrations during US06 cycle

Grahic Jump Location
Fig. 5

Estimation of ammonia coverage ratio during US06 cycle

Tables

Errata

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In