Method and control device for operating a transmission

A method for operating a motor vehicle having a transmission (10), an internal combustion engine (22), and an electric machine (24), the transmission (10) having a hydraulic system (12) for supplying hydraulic fluid, the hydraulic system (12) including a dual-circuit pump (14) having a primary flow (16) and a secondary flow (18), the hydraulic system (12) further including a system pressure valve (32), a lubricating valve (34), a primary circuit (28), and a secondary circuit (30), the method comprising:

• driving the dual-circuit pump (14) by the internal combustion engine (22) and the electric machine (24) at a resultant pump speed (n3) via an intermediate connection of a superposition gear unit (20), the superposition gear unit (20) superimposing a first rotational speed (n1) of the internal combustion engine (22) and a second rotational speed (n2) of the electric machine (24) to provide the resultant pump speed (n3);
• determining, with a control device (44), whether a subset (UM) is less than a subset threshold value (UMTH) when a target value of a required primary flow (16) increases from a first primary flow target value (PFS1) to a second primary flow target value (PFS2) in a dual-circuit operating state, the second primary flow target value (PFS2) being higher than a current primary flow actual value (PFI), the subset being a difference between the second primary flow target value (PFS2) and the primary flow actual value (PFI);
• and
• increasing, with the control device (44), the second rotational speed (n2) when the subset (UM) is less than the subset threshold value (UMTH) such that the primary flow actual value (PFI) corresponds to the second primary flow target value (PFS2).