Control Strategy Research of a Selective Catalytic Reduction System for Heavy-Duty Application

An AdBlue dosing control strategy of the selective catalytic reduction（SCR） system is developed for a heavy-duty diesel（HDD） engine. The strategy includes a raw emission prediction model, an ammonia（NH;）coverage prediction model, a transient heat hysteresis correction algorithm, an NH;leakage control model for transient operation conditions, and a feedback controller（FBC）. FBC has been developed by using mathematical manipulation to change output signal of sensor based on cross-sensitivity of nitrogen oxide（NO;） sensor to NH;.The quantification of control parameters is based on experiments and Nyquist stability criterion. FBC is enabled in most test conditions to satisfy the stability requirements. NOxconversion（DeNO;） efficiency of SCR system is 82.4% in European steady-state cycle（ESC） test and 80.3% in European transient cycle（ETC） test, while the leakage of NH;is under 10-5 volume fraction in average.