Method for operating an electric drive system for a motor vehicle, in particular for a motor vehicle

Abstract

Method for operating an electric drive system (10) of a motor vehicle (12), in which:- the electric drive system (10) has:◯ a vehicle axle (14) with a first vehicle wheel (18) and a second vehicle wheel (20);◯ a first electric machine (24);◯ a second electric machine (26); and◯ an accelerator pedal (28) which can be actuated by a person and thereby moved into different positions, whereby a respective torque to be provided by the electric drive system (10) for driving the motor vehicle (12) can be adjusted;- the electric drive system (10) can be operated in a first operating mode in which the first electric machine (24) is coupled to the vehicle wheels (18, 20) in a torque-transmitting manner, while the second electric machine (26) is decoupled from the vehicle wheels (18, 20), and- the electric drive system (10) can be operated in a second operating mode,in which the first electric machine (24) is coupled to the vehicle wheels (18, 20) in a torque-transmitting manner, while the second electric machine (26) is coupled to the two vehicle wheels (18, 20) in a torque-transmitting manner, characterized in that the electric drive system (10) is switched from the first operating mode to the second operating mode when a first changeover condition is met, which comprises that a time derivative of an accelerator pedal value characterizing at least one of the positions of the accelerator pedal (28) is greater than a first limit value and, at the same time, the accelerator pedal value is greater than a second limit value and, at the same time, the accelerator pedal value is less than a third limit value.

Claims

[1] Method for operating an electric drive system (10) of a motor vehicle (12), in which: - the electric drive system (10) comprises: ◯ a vehicle axle (14) with a first vehicle wheel (18) and a second vehicle wheel (20); ◯ a first electrical machine (24); ◯ a second electrical machine (26); and ◯ an accelerator pedal (28) which can be actuated by a person and thereby moved into different positions, whereby a respective torque to be provided by the electric drive system (10) for driving the motor vehicle (12) can be adjusted; - the electric drive system (10) is operable in a first operating mode in which the first electric machine (24) is coupled to the vehicle wheels (18, 20) in a torque-transmitting manner, while the second electric machine (26) is decoupled from the vehicle wheels (18, 20), and - the electric drive system (10) is operable in a second operating mode in which the first electric machine (24) is coupled to the vehicle wheels (18, 20) in a torque-transmitting manner, while the second electric machine (26) is coupled to the two vehicle wheels (18, 20) in a torque-transmitting manner, characterized by that the electric drive system (10) is switched from the first operating mode to the second operating mode when a first changeover condition is met, which comprises that a time derivative of an accelerator pedal value characterizing at least one of the positions of the accelerator pedal (28) is greater than a first limit value and at the same time the accelerator pedal value is greater than a second limit value and at the same time the accelerator pedal value is less than a third limit value. [2] Method according to claim 1, characterized bythat the electric drive system (10) has a differential gear (34), a first differential output shaft (38) permanently coupled to the first vehicle wheel (18) in a torque-transmitting manner, a second differential output shaft (40) permanently coupled to the second vehicle wheel (20) in a torque-transmitting manner, and a differential input shaft (36). [3] Method according to claim 2, characterized by in that in the first operating mode and in the second operating mode, the first electric machine (24) is coupled to the differential input shaft (36) in a torque-transmitting manner and is thereby coupled to the vehicle wheels (18, 20) via the differential input shaft (36), the differential gear (34) and the differential output shafts (38, 40) in a torque-transmitting manner. [4] Method according to claim 2 or 3, characterized byin that in the first operating mode, the second electric machine (26) is decoupled from the differential output shafts (38, 40) and from the differential input shaft (36) and from the differential gear (34) and thereby from the vehicle wheels (18, 20). [5] Method according to one of claims 2 to 4, characterized by in that in the second operating mode, the second electric machine (26) is coupled to the differential input shaft (36) in a torque-transmitting manner and is thereby coupled to the vehicle wheels (18, 20) via the differential input shaft (36) and the differential gear (34) and the differential output shafts (38, 40) in a torque-transmitting manner. [6] Method according to one of claims 2 to 5, characterized by that the first electric machine (24) is permanently coupled to the differential input shaft (36) in a torque-transmitting manner. [7] Method according to one of claims 2 to 5, characterized bya first coupling device (K1) which can be switched between: - a first coupling state in which, by means of the first coupling device (K1), the second electric machine (26) is coupled to the differential input shaft (36) in a torque-transmitting manner and thereby to the vehicle wheels (18, 20) via the differential input shaft (36) and the differential gear (34) and the differential output shafts (38, 40); and - a first decoupling state in which the second electric machine (26) is decoupled from the differential input shaft (36) and the differential output shafts (38, 40) and the differential gear (34) and thereby from the vehicle wheels (18, 20). [8] Method according to one of the preceding claims, characterized bythat the electric drive system (10) is switched from the first operating mode to the second operating mode when a second changeover condition is met, which comprises, by means of a navigation system of the motor vehicle (12), determining a current position of the motor vehicle (12) on the earth and a curve ahead of the motor vehicle (12) and, at the same time, a distance between a turning point of the curve and the current position is less than a fourth limit value. [9] Method according to claim 8, characterized by that the second change condition comprises that a direction indicator of the motor vehicle (12) is active. [10] Method according to claim 8 or 9, characterized bythat when the second changeover condition is met, the second electric machine (26) is coupled to the first vehicle wheel (18) in a torque-transmitting manner, bypassing the differential gear (34) and bypassing the second differential output shaft (40) and bypassing the differential input shaft (36) and bypassing the second vehicle wheel (20).

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