Sliding-mode Control of Ammonia Coverage Ratio for Automotive Selective Catalytic Reduction Systems

This paper presents a sliding-mode control method for automotive Selective Catalytic Reduction (SCR) systems to regulate ammonia coverage ratios to desired levels. SCR systems have been widely adopted on Diesel powered vehicles to reduce tailpipe NOx emissions. To maintain a high NOx removal efficiency as well as acceptable ammonia slip, the SCR ammonia coverage ratio has to be critically controlled to balance such a tradeoff. A sliding-mode control method is analytically developed to track the target ammonia coverage ratio. Its tracking performance under bounded measurement noise is evaluated. The control input saturation is explicitly considered and its effect on SCR transient behavior is assessed in the design procedure. Simulation results indicate the proposed control can effectively track the target ammonia coverage ratio and comparative study against a traditional PID control demonstrates the improvement of robustness in the presence of bounded disturbances.

[1]  Robert E. Hayes,et al.  Simulation study of SCR catalysts with individually adjusted ammonia dosing strategies , 2015 .

[2]  Junmin Wang,et al.  Observer-Based Estimation of Air-Fractions for a Diesel Engine Coupled With Aftertreatment Systems , 2013, IEEE Transactions on Control Systems Technology.

[3]  M. Iwasaki,et al.  A comparative study of “standard”, “fast” and “NO2” SCR reactions over Fe/zeolite catalyst , 2010 .

[4]  Junmin Wang,et al.  Adaptive and Efficient Ammonia Storage Distribution Control for a Two-Catalyst Selective Catalytic Reduction System , 2012 .

[5]  Junmin Wang,et al.  Development and experimental studies of a control-oriented SCR model for a two-catalyst urea-SCR system , 2011 .

[6]  Andrew Peter Walker,et al.  Future Challenges and Incoming Solutions in Emission Control for Heavy Duty Diesel Vehicles , 2016, Topics in Catalysis.

[7]  Christopher H. Onder,et al.  Control of an SCR catalytic converter system for a mobile heavy-duty application , 2006, IEEE Transactions on Control Systems Technology.

[8]  Junmin Wang,et al.  An extended Kalman filter for NOx sensor ammonia cross-sensitivity elimination in selective catalytic reduction applications , 2010, Proceedings of the 2010 American Control Conference.

[9]  Junmin Wang,et al.  NO and NO2 Concentration Modeling and Observer-Based Estimation Across a Diesel Engine Aftertreatment System , 2011 .

[10]  T. Johnson.  Review of Vehicular Emissions Trends , 2015 .

[11]  M. Elsener,et al.  Urea-SCR: a promising technique to reduce NOx emissions from automotive diesel engines , 2000 .

[12]  Junmin Wang,et al.  Adaptive Sliding-Mode Observer Design for a Selective Catalytic Reduction System of Ground-Vehicle Diesel Engines , 2016, IEEE/ASME Transactions on Mechatronics.

[13]  Gordon G. Parker,et al.  Model-Based Estimation and Control System Development in a Urea-SCR Aftertreatment System , 2008 .

[14]  Junmin Wang,et al.  Estimation and adaptive nonlinear model predictive control of selective catalytic reduction systems in automotive applications , 2016 .

[15]  Fengjun Yan,et al.  Control of diesel engine dual-loop EGR air-path systems by a singular perturbation method , 2013 .

[16]  Maria Caterina Turco,et al.  Adsorption, Activation, and Oxidation of Ammonia over SCR Catalysts , 1995 .

[17]  Frank Willems,et al.  Experimental Demonstration of a New Model-Based SCR Control Strategy for Cleaner Heavy-Duty Diesel Engines , 2011, IEEE Transactions on Control Systems Technology.

[18]  Junmin Wang,et al.  Nonlinear Observer Design of Diesel Engine Selective Catalytic Reduction Systems With $\hbox{NO}_{x}$ Sensor Measurements , 2015, IEEE/ASME Transactions on Mechatronics.

[19]  Junmin Wang,et al.  Control-oriented model for integrated diesel engine and aftertreatment systems thermal management , 2014 .

[20]  Junmin Wang,et al.  A Two-Cell Backstepping-Based Control Strategy for Diesel Engine Selective Catalytic Reduction Systems , 2011, IEEE Transactions on Control Systems Technology.

[21]  Young Sun Mok,et al.  Decomposition of Urea into NH3 for the SCR Process , 2004 .