METHOD FOR CONTROLLING AN EXHAUST-GAS AFTERTREATMENT SYSTEM OF AN INTERNAL COMBUSTION ENGINE HAVING AT LEAST TWO SCR CATALYTIC CONVERTERS CONNECTED IN SERIES

A method for controlling an exhaust-gas aftertreatment system of an internal combustion engine (10) having at least two SCR catalytic converters (4, 19) connected in series, the exhaust-gas aftertreatment system having a bypass (15) including a bypass valve (16) around the first SCR catalytic converter (4), and exhaust gases of the internal combustion engine (10) are completely or at least partially routed around the first SCR catalytic converter (4) via the bypass (15), the method having the following steps:Ascertaining an activation of an exhaust brake operation for the internal combustion engine (10),ascertaining a first actual temperature (TActual,Cat1) for the first SCR catalytic converter (4),ascertaining an actual NH3 storage level (NH3Actual,Cat1) for the first SCR catalytic converter (4),ascertaining a modeled, maximally permitted NH3 storage level (NH3Limit) as a function of the actual NH3 storage level (NH3Actual,Cat1)ascertaining a future temperature (Tpre) for the first SCR catalytic converter (4) with the aid of a predictive temperature model,ascertaining a comparison as a function of the ascertained first actual temperature (TActual,Cat1) and the ascertained future temperature (TPre),actuating the bypass valve (16) as a function of the ascertained comparison, in particular completely or partially opening the bypass valve (16).