Control strategy research of a selective catalytic reduction system for heavy-duty application

Abstract

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 (NH3) coverage prediction model, a transient heat hysteresis correction algorithm, an NH3 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 x ) sensor to NH3. 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. NO x conversion (DeNO x ) 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 NH3 is under 10−5 volume fraction in average.