Model predictive control of selective catalytic reduction in diesel-powered vehicles

This paper proposes a method to synthesize an optimal controller for the SCR section of the diesel exhaust after-treatment system, which is based on a system model consisting of coupled hyperbolic and parabolic partial differential equations (PDEs). This results in a boundary control problem, where the control objectives are to reduce the amount of NO_x emissions and ammonia slip to the fullest extent possible using the inlet concentration of ammonia as the manipulated variable. The proposed method combines the method of characteristics and spectral decomposition to produce a non-linear model predictive control (NMPC) approach. The results show that the proposed NMPC is able to achieve a very high level of control performance in terms of NO_x and ammonia slip reduction.