基于模型的SCR系统还原剂供给量自适应控制

Model-Based Reductant Supply Adaptation for SCR Control

提出一种基于模型的选择性催化还原(SCR)系统还原剂供给量自适应方法以排除催化剂老化程度、还原剂质量分数、供给单元供给精度变化所带来的影响,当系统监测到模型转化效率和传感器转化效率的偏差超过一定阈值时激活自适应功能,通过在欠喷射状态下计算当前SCR系统工作状态与正常工作状态的差异,从而得出准确的修正因子对基础喷射量进行比例修正.在尿素溶液质量分数稳定的情况下,连续运行18次自适应修正功能,计算得到的修正因子最大误差仅为1.1%;在尿素溶液质量分数变化的情况下,该功能可通过2~3次计算,使得修正因子的误差控制在5%以内并逐步逼近理论修正因子.这一自适应方法使得SCR系统总能处于最佳的还原剂供给控制状态,最大程度地实现降低NO_(x)排放和NH_(3)排放的目标.

A model-based adaptation for reductant(AdBlue)supply of selective catalytic reduction(SCR)system is proposed to keep the reductant supply adapting the deviation caused by catalyst aging,reductant concentration drift and supply accuracy variation.When a certain deviation between model conversion efficiency and sensor conversion efficiency is detected,the adaptive function is activated.The conversion efficiency difference between the current working state and the normal working state of this SCR system is calculated during an insufficient injection period so as to obtain the accurate correction factor,and the basic injection quantity can be modified based on this factor.The maximum error of the 18 calculated correction factors from 18 WHTC cycles is only 1.1%when using standard AdBlue;After urea solution concentration changes,the calculated correction factor error is within 5%when comparing with the theoretical correction factor after 2-3 rounds adaptation function running.The adaptation function ensure SCR system always stay in appropriate dosing control state,make best for NO_(x) emissions and NH_(3) emissions control.