(125a) Servo-Control of Selective Catalytic Reduction in Diesel-Powered Vehicles

Heavy-duty diesel engines play an important role in transportation and power generation applications, power systems for vehicles and industrial equipments. However, essential disadvantages of diesel engines contain the emission of significant levels of particulate matter and oxides of nitrogen (NO_x), which are known to have detrimental health and environmental effects. As a consequence, manufacturers have developed emission control technologies in order to meet or exceed mandated requirements. The main components of the diesel engine emission system include the diesel oxidation catalyst(DOC), which is oxidises carbon monoxide and hydrocarbons, a particulate filter (DPF) to capture soot and selective catalytic reduction(SCR) [1]. Within the SCR section of the emission control system, NO_x is catalytically reduced to nitrogen and water using ammonia.

Developing reliable dynamic models and control techniques aimed at the operation of SCR has attracted attention of researchers in academia and industry. To balance high NO_x reduction efficiency and low ammonia slip, several urea dosing control techniques have been recently proposed [2], [3]. However, these techniques developed to date use models comprised of ordinary differential equations (ODEs) to control the SCR and use inlet and outlet sensors for the state and parameter estimation. The main drawback of these techniques is that models developed based on ODE cannot capture important SCR dynamics, so the highest performance of the SCR cannot be achieved; however, good performance can be achieved by using models involving a large number of ODEs at the expense of computational time. In the present work, we are employing the full complex SCR model which is characterized as distributed parameter systems. More precisely, the complex SCR model is consisting of coupled hyperbolic and parabolic partial differential equations (PDEs). In the present work, we are designing a feedforward boundary controller to address the reduction problem of the amount of NO_x emissions.

[1] Bertelsen, Bruce I. ``Future US motor vehicle emission standards and the role of advanced emission control technology in meeting those standards." Topics in Catalysis 16.1 (2001): 15-22.

[2] Upadhyay, Devesh, and Michiel Van Nieuwstadt. ``Model based analysis and control design of a urea-SCR deNO_x after-treatment system." Journal of dynamic systems, measurement, and control 128.3 (2006): 737-741.

[3] Hsieh, Ming-Feng, and Junmin Wang. ``A two-cell backstepping-based control strategy for diesel engine selective catalytic reduction systems." IEEE Transactions on Control Systems Technology 19.6 (2011): 1504-1515.