Dynamic modeling of a three-way catalyst for SI engine exhaust emission control

| Automotive emissions are severely regulated. Since 1980, a three-way catalyst (TWC) has been used to convert harmful emissions of hydrocarbons, carbon monoxide, and oxides of nitrogen into less harmful gases in order to meet these regulations. The TWC's e ciency of conversion of these gases is primarily dependent on the mass ratio of air to fuel (A=F ) in the mixture leaving the exhaust manifold and entering the catalyst, the velocity of the exhaust mass, and the temperature of the catalyst. The goal of this paper is to develop a dynamic, control-oriented model of a TWC. First, the measurement capabilities will be described. Then, a simpli ed, dynamic catalyst model that can be determined on the basis of medium bandwidth A=F measurements and low bandwidth temperature and emission measurements will be developed and validated. Keywords|Control systems, modeling, nonlinear systems, road vehicles.