Method for operating a drive system, the drive system comprising a rectifier, a first electric motor, which is connected to the DC voltage-side terminal of the rectifier by means of a bidirectionally operable DC-to-AC converter, and a further motor that can be fed from an inverter, the DC voltage-side terminal of the inverter and the DC voltage-side terminal of the DC-to-AC converter being connected in parallel with the DC voltage-side terminal of the rectifier, the AC voltage-side terminal of the inverter being connected to the further motor, and the AC voltage-side terminal of the AC-to-DC converter being connected to the first motor, the value or curve of the voltage applied to the DC voltage-side terminal of the inverter, i.e. the DC-link voltage U_ZK, being detected in particular within the converter, in particular within the casing of the converter and thus outside the casing of the inverter, and the value of a measure for the fluctuation range of the curve being determined therefrom, the converter controlling the power flow delivered by the first motor depending on, in particular depending only on, the value or the curve thereof, by controlling the torque of the first motor towards a desired torque value M_Soll, characterised in that one of two or more different states of the drive system is always activated, in that the converter has two or more structures (21, 22, 23) by each of which a desired torque value M_Soll can be provided, in that, depending on the activated state (Z1, Z2, Z3, Z4), only one of the structures (21, 22, 23) provides the desired torque value M_Soll, in that, in a first structure, the voltage applied to the DC voltage-side terminal of the bidirectional DC-to-AC converter is controlled by means of a linear controller structure, and a desired torque is provided in the process, in that, in a further structure (22, 23), the speed of the first motor is controlled by means of a further linear controller structure, and a desired torque is provided in the process. the drive system comprising a rectifier, a first electric motor, which is connected to the DC voltage-side terminal of the rectifier by means of a bidirectionally operable DC-to-AC converter, and a further motor that can be fed from an inverter, the DC voltage-side terminal of the inverter and the DC voltage-side terminal of the DC-to-AC converter being connected in parallel with the DC voltage-side terminal of the rectifier, the AC voltage-side terminal of the inverter being connected to the further motor, and the AC voltage-side terminal of the AC-to-DC converter being connected to the first motor, the value or curve of the voltage applied to the DC voltage-side terminal of the inverter, i.e. the DC-link voltage U_ZK, being detected in particular within the converter, in particular within the casing of the converter and thus outside the casing of the inverter, and the value of a measure for the fluctuation range of the curve being determined therefrom, the converter controlling the power flow delivered by the first motor depending on, in particular depending only on, the value or the curve thereof, by controlling the torque of the first motor towards a desired torque value M_Soll, characterised in that one of two or more different states of the drive system is always activated, in that the converter has two or more structures (21, 22, 23) by each of which a desired torque value M_Soll can be provided, in that, depending on the activated state (Z1, Z2, Z3, Z4), only one of the structures (21, 22, 23) provides the desired torque value M_Soll, in that, in a first structure, the voltage applied to the DC voltage-side terminal of the bidirectional DC-to-AC converter is controlled by means of a linear controller structure, and a desired torque is provided in the process, in that, in a further structure (22, 23), the speed of the first motor is controlled by means of a further linear controller structure, and a desired torque is provided in the process.