Control of an SCR catalytic converter system for a mobile heavy-duty application

Abstract

Selective catalytic reduction (SCR) is well known for exhaust gas aftertreatment in power plant applications. In the near future, it will be introduced in Europe in mobile heavy-duty diesel applications. Stringent specifications and the dynamic operation mode of such applications demand advanced control strategies. Such a control strategy is presented here. It incorporates a model-based feedforward controller (FFC) which handles the known dynamics of the plant. It further contains a feedback controller (FBC) to compensate for disturbances and slowly varying parameters. The realization of the feedback control loop is possible only due to the use of a nitrogen oxide (NO/sub x/) sensor which is cross-sensitive against ammonia (NH/sub 3/), and the implementation of a procedure separating the detection of NO/sub x/ and NH/sub 3/.