Modelling of selective catalytic reduction systems using discrete-time Linear Parameter Varying models

In this work, a Linear Parameter Varying (LPV) model of the Selective Catalytic Reduction (SCR) system, used for NOx reduction placed as after-treatment systems in diesel engines is developed. The LPV model structure is formed utilising the physical properties of the system yielding only 7 unknown parameters for a third order model structure of the SCR, which is a significant reduction in number of parameters in comparison with other nonlinear models used in this paper. The states of the model however, do not possess any physical interpretation. The LPV model structure is validated using real measured data from cell tests at Scania AB with promising results. The proposed model is compared to previous global nonlinear models of the system, i.e. a nonlinear state space model and a Hammerstein-Wiener model of the system.

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