According to the working principle of selective catalytic reduction(SCR) system

the catalyst integration scheme of DeNOx system was described. Focusing on the main problems faced by SCR control system

the advantages and disadvantages of traditional and advanced SCR control systems were highlighted. Research results show that the main problems faced by the SCR control systems are the nonlinear characteristics of the SCR model

the coupled control with multi-time scales and the reliability of commercial sensors used in the harsh environment. The NOx conversion efficiency of the open loop control system can reach 60%~80%

only meeting the requirements of China's CN Ⅳ and CN Ⅴ emission regulations. The closed-loop control system has a higher NOx conversion efficiency and can meet more stringent emission regulations. Advanced SCR control technology has good control effect and robustness

and can more effectively control NOx emissions and NH3 slip. In addition

the coordinated control of the engine and its aftertreatment system increases the controllability

which can further reduce the pollutant emissions from diesel vehicles.