Patent attributes
A method is provided for controlling a hybrid drive train comprising a first partial drive train including an internal combustion engine having a crankshaft and a second partial drive train, which is separated from the first partial drive train by a torsional elasticity, having an electric machine with a rotor. A rotational characteristic value of the first partial drive train is detected via a sensor arranged on the torsional elasticity. A rotational characteristic value of the rotor is detected via a device engaged with the rotor. A quality index is determined based on the rational characteristic value of the first partial drive train and the rotational characteristic value of the rotor. The electric machine is controller to optimize the quality index.