ADRC based cascade controller design for urea selective catalytic reduction system

Urea selective catalytic reduction (urea-SCR) control is very important for diesel engine emissions. In this paper, a Continuous Stirred Tank Reactor(CSTR) is used to represent the SCR model, then a cascade control system is deduced based on active disturbance rejection control (ADRC) strategy. The cascade control system consists of two ADRC controllers, and every ADRC controller contains a Extended State Observer (ESO) to estimate the total disturbance and a PID feedback control law to handle the ammonia coverage ratio tracking. Finally, the simulation results are given to demonstrate the effectiveness of the proposed control scheme tracking the reference and the robustness to the noise.