Abstract:

For simultaneously achieving high NOx conversion efficiency and low ammonia slip, a new control-oriented model presentation of urea-SCR systems is developed. And a novel nonlinear controller using backstepping is presented, which drives the parameterdependent but also varying nonlinear system totrack the desired ammonia coverage ratio. Taking into account the lower vehicle weight and costs, the proposed controller was suitable for simple SCR aftertreatment system of light-duty vehicle. Model uncertainties including parameter error, etc. were also considered as additive disturbance inputs, and the closedloop error system dynamics was analysed in the frame of input-to-state stable. Based on a validated enDYNA diesel engine model with urea-SCR aftertreatment systems, transient ECE(Economic Commission for Europe）driving cycle simulation is conducted to evaluate the effectiveness of the proposed control strategy. And comparisons with conventional PID(Proportion Integration Differentiation) urea-SCR controller are presented to show the adva
ntages of the proposed control strategy.

Key words: nonlinear control, backstepping, input-to-state stable, urea selective catalytic reduction(ureaSCR)