METHOD AND CONTROL UNIT FOR REGULATING A FILL LEVEL OF A STORAGE OF A CATALYTIC CONVERTER FOR AN EXHAUST GAS COMPONENT

A method is described for regulating a filling of an exhaust gas component storage of a catalytic converter in the exhaust gas of an internal combustion engine, in which an actual fill level of the exhaust gas component storage is ascertained using a first system model, and in which a base lambda setpoint value for a first control loop is predefined by a second control loop. The method is distinguished by the fact that in the second control loop an initial value for the base lambda setpoint value is converted into a fictitious fill level via a system model identical to the first system model, the fictitious fill level being compared with a setpoint value for the fill level output by a setpoint value generator, and the base lambda setpoint value being iteratively changed as a function of the comparison result, if the comparison result indicates a difference between the setpoint value for the fill level and the fictitious fill level, which is greater than a predefined degree, and the base lambda setpoint value not being changed if the comparison result indicates no difference between the setpoint value for the fill level and the fictitious fill level.