Urea-SCR Process Control for Diesel Engine Using Feedforward-Feedback Nonlinear Method

Urea selective catalytic reduction (urea-SCR) process control is very important for exhaust gas aftertreatment in diesel engines. A control system tracking ammonia coverage ratio is designed to achieve high NOx conversion efficiency and low ammonia slip for urea-SCR process in this paper. The control system consists of a nonlinear feedforward controller based on flatness and a PI feedback controller to deal with the uncertainties and disturbance. Furthermore, a tuning method of controller parameters is presented based on randomized algorithms. Finally, the simulation results are given to demonstrate the effectiveness of the proposed control scheme.