Method for controlling a drive device of a hybrid vehicle, which drive device comprises an internal combustion engine, a first electric machine, a second electric machine and a battery, wherein the drive device can be operated, in order to drive the hybrid vehicle, in each of the following operating modes: a first electric operating mode (EV 1), in which the second electric machine, in electric motor mode, causes a traction drive torque, while the internal combustion engine is stationary; a second electric operating mode (EV 2), in which a wheel torque acts on the second electric machine and the second electric machine, in generator mode, generates current in order to charge the battery, while the internal combustion engine is stationary; a series operating mode (Ser), in which the internal combustion engine drives a first electric machine in order to generate electrical energy which drives the second electric machine which causes a traction drive torque; and a parallel operating mode (Par), in which the internal combustion engine causes a traction drive torque, wherein, in the series or parallel operating mode (Ser; Par), the internal combustion engine, in a first series or parallel charging mode (Ser lad; Par lad), drives the electric machine (3, 4) to generate additional electrical charging energy in order to charge the battery, and the method comprises: determining a cost limit (b C), controlling the drive device by means of a first changeover logic in order to activate the first parallel or series charging mode, ascertaining a series and/or a parallel cost function (Cser(t); Cpar(t)), which are both based on the relationship between a required fuel performance (ΔPf,ser(t,wl); (ΔPf,par(t,wl)) in order to charge the battery and a resulting battery charging power (ΔPbat,chg,ser(t,wl); ΔPbat,chg,par(t,wl)), comparing series and/or parallel cost functions (Cser(t); Cpar(t)) with the cost limit (b C), activating the first series or parallel charging mode when the cost function is at an operating point below a cost limit (b C), characterized in that determining the cost limit (b C) comprises: selecting a standard cost limit (b C,i), and in an operating time period: determining an optimized cost limit (b C,opt) on the basis of a speed profile and/or adjusting the standard cost limit (b C,i) on the basis of an operating state (BS 1, BS 2), an operating strategy and/or a driver request, wherein the method comprises: determining a charging mode at an operating point at which the series and/or parallel cost function (C ser (t); C par (t)) corresponds to charging costs (C add (t)) increased above a level of consumption-optimized costs (C opt (t)), for which: C add t i = C opt t i + b cLimit − C opt t i T f where b cLimit is an absolute upper cost limit, and, for the factor T f: T f ≥ 1. a first electric operating mode (EV 1), in which the second electric machine, in electric motor mode, causes a traction drive torque, while the internal combustion engine is stationary; a second electric operating mode (EV 2), in which a wheel torque acts on the second electric machine and the second electric machine, in generator mode, generates current in order to charge the battery, while the internal combustion engine is stationary; a series operating mode (Ser), in which the internal combustion engine drives a first electric machine in order to generate electrical energy which drives the second electric machine which causes a traction drive torque; and a parallel operating mode (Par), in which the internal combustion engine causes a traction drive torque, determining a cost limit (b C), controlling the drive device by means of a first changeover logic in order to activate the first parallel or series charging mode, ascertaining a series and/or a parallel cost function (Cser(t); Cpar(t)), which are both based on the relationship between a required fuel performance (ΔPf,ser(t,wl); (ΔPf,par(t,wl)) in order to charge the battery and a resulting battery charging power (ΔPbat,chg,ser(t,wl); ΔPbat,chg,par(t,wl)), comparing series and/or parallel cost functions (Cser(t); Cpar(t)) with the cost limit (b C), activating the first series or parallel charging mode when the cost function is at an operating point below a cost limit (b C), selecting a standard cost limit (b C,i), and in an operating time period: determining an optimized cost limit (b C,opt) on the basis of a speed profile and/or adjusting the standard cost limit (b C,i) on the basis of an operating state (BS 1, BS 2), an operating strategy and/or a driver request, determining an optimized cost limit (b C,opt) on the basis of a speed profile and/or adjusting the standard cost limit (b C,i) on the basis of an operating state (BS 1, BS 2), an operating strategy and/or a driver request, determining a charging mode at an operating point at which the series and/or parallel cost function (C ser (t); C par (t)) corresponds to charging costs (C add (t)) increased above a level of consumption-optimized costs (C opt (t)), for which: C add t i = C opt t i + b cLimit − C opt t i T f where b cLimit is an absolute upper cost limit, and, for the factor T f: T f ≥ 1.