Modeling of a Three-Way Catalytic Converter with Respect to Fast Transients of λ-Sensor Relevant Exhaust Gas Components

For the control of three-way catalytic converters (TWCs), simplified models of not only the TWC but also the λ-sensors upstream and downstream of the TWC are required. The accurate interpretation of the sensor signals makes the correction or online identification of model parameters possible. Thus, a precise estimate of the species that mainly drive the sensor's output is indispensable. To gain insight into the main reactions driving the TWCs' behavior, a model derived from the literature has been applied and adjusted to measured exhaust gas transients. These were obtained from fast gas measurement devices, where all components have been measured with T90 < 30 ms. Apart from the components that are under the regime of legislation, such as NO, CO, and HC, also species that significantly influence the λ-sensor signal, such as H2 and O2, have been measured. The model agrees well with the measurements and can thus be used as a starting point toward control-oriented (simplified) modeling of TWCs.