Method for operating an electric drive train of a working machine, electric drive train for a working machine and working machine

Abstract

Method for operating an electric drive train (11) of a working machine (10), wherein the drive train (11) comprises a working drive (20) with an electric working motor (21) and a driving drive (30) with an electric driving motor (31) and vehicle wheels (32), wherein the working machine (10) experiences an external deceleration and wherein a braking force acting on the vehicle wheels (32) due to the deceleration may be less than a driving force acting on the vehicle wheels (32) due to a moment of inertia of the driving motor (31), characterized in that the driving motor (31) is supplied with a current opposite to its direction of operation (300, 301) to reduce its speed, when it is predictively recognized by means of situation detection that the braking force acting on the vehicle wheels (32) due to the deceleration is less than the driving force (200) acting on the vehicle wheels (32).

Description

[0001] The present invention relates to a method for operating an electric drive train of a working machine according to the preamble of claim 1, an electric drive train for a working machine according to the preamble of claim 11 and a corresponding working machine.

[0002] Electrically driven work machines such as wheel loaders, compact loaders, telescopic handlers, dumpers, and excavators are known in the prior art. These electrically driven work machines are either purely electric, meaning they rely solely on an electric battery for their energy supply, or they are diesel-electric, meaning the required energy is supplied by a diesel-driven generator, usually in conjunction with an electrical buffer storage device, such as a suitably sized capacitor. In all cases, the mechanical power required for travel and work is provided by one or more electric motors. Hybrid-electric work machines are also known, in which the mechanical power required for operation is primarily provided by an internal combustion engine, usually a diesel engine.An additional electric motor is powered by a battery and typically performs a so-called boost function.

[0003] In this context, DE 20 2014 000 738 U1 describes a purely electrically driven wheel loader, which has a first electric motor for a travel drive and a second electric motor for a working drive.

[0004] From EP 0 962 597 A2 a battery-powered working machine is known which has two electric motors for the driving drive and another electric motor for the working drive.

[0005] DE 10 2006 007 466 A1 discloses a drive system for a working machine. The drive system comprises a driven traction device and a gearbox.

[0006] The transmission serves to drive at least one traction device. The drive system also includes a control unit which determines a traction capacity related to the ground or surface, which is associated with the at least one driven traction device and serves to limit the amount of torque transmitted from the transmission to the at least one driven traction device if the transmitted torque exceeds the traction capacity.

[0007] US Patent 2006 / 0025917A1 describes a system for controlling the slip of a traction device of a working machine engaged with the ground. The system includes a true slip computer that transmits a signal for the actual slip experienced by the working machine. The system also includes a ground condition selector that transmits a ground condition signal according to a selected ground condition.

[0008] US Patent 2006 / 0069487A1 describes a method for power dissipation in a driven machine with an electric drive system and a mechanical braking system. The machine's inclination and speed are determined. Based on these values, a deceleration requirement is calculated. A first portion of the deceleration requirement is allocated to the electric drive system, provided this first portion is less than or equal to the deceleration capacity of the electric drive system. A second portion of the deceleration requirement is allocated to the mechanical braking system if the deceleration requirement exceeds the deceleration capacity of the electric drive system.

[0009] From US patent 2013 / 0066496A1, a hybrid work vehicle is known, consisting of an engine, a drive wheel, a power take-off (PTO) shaft, and a power transmission system for transferring power from the engine to the drive wheel and the PTO shaft. The power transmission system splits at a junction into a drive train for powering the drive wheel and a PTO drive train for driving the PTO shaft. A continuously variable transmission (CVT) is provided in the drive train, and a motor-generator is provided in the power transmission system between the engine and the junction. The motor-generator functions as a generator using the power of the internal combustion engine and also acts as an electric motor to drive the power transmission system. The hybrid work vehicle includes a controller for regulating the output speed of the motor-generator, which functions as an electric motor.

[0010] DE 11 2013 000 102 T5 describes a work vehicle comprising at least one drive motor and a first control device which generates a speed command value used to control the motor and adds a current driving speed of the work vehicle to a relationship between a torque command value as a command value for a torque to be generated in the motor and a driving speed of the work vehicle in order to generate a first torque command value, and a second control device which generates a second torque command value based on the speed command value generated by the first control section and the current driving speed.

[0011] DE 199 31 141 A1 discloses a vehicle drive arrangement with at least two driven wheels, the drive torques of which can be individually controlled by a control device, wherein the control device is connected to a sensor arrangement with at least one sensor. In order to prevent wheel slippage with such a drive arrangement, the control device continuously determines a maximum torque for each wheel using a signal from the sensor arrangement and reduces the drive torque accordingly if the determined drive torque no longer maintains a predetermined limit value from the maximum torque.

[0012] DE 10 2018 210 911 A1 relates to a method for operating a drive system for a working machine, wherein a first electric motor is assigned to a travel drive of the drive system and a second electric motor is assigned to a power drive of the drive system. An electrical energy storage device is assigned to both the travel drive and the power drive, wherein the first electric motor is operated in generator mode to generate braking power for the travel drive and wherein electrical power is generated in generator mode.

[0013] EP 2 937 467 A1 relates to an anti-slip method for an electric loader intended for handling rock material and equipped with a power supply cable for supplying electric current from a power grid, for example a power grid present in a mine, to the loader, wherein the power supply cable is arranged on a reel in the loader.The method comprises measuring the movement of the power supply cable relative to the loader, measuring the movement of one or more wheels of the loader or the axle that rotates the wheel, converting the movement data obtained by measuring the wheel or axle into movement data of the loader, comparing the measured movement of the power supply cable with the movement data of the loader obtained by measuring the wheel or axle, and, if the measured movement of the power supply cable and the movement data of the loader obtained by measuring the wheel or axle differ from each other by more than a given predetermined limit, limiting the torque that rotates the wheel.

[0014] However, the known electrically powered work machines have a disadvantage in that, due to the design of the electric motors used for their drive, they exhibit a comparatively high inertia in the drive train when decelerating the machine, i.e., when reducing the speed of the electric motor, especially when braking is achieved via regenerative braking or a mechanical friction brake. The cause of this behavior lies in the comparatively very high rotational speeds of an electric motor in conjunction with its high inertia. An electric motor rotating at full load therefore possesses significantly greater rotational energy than a comparably powerful internal combustion engine at full load.This can lead to a situation with an electrically powered wheel loader, for example, where when the bucket plunges into a mound of earth or similar from medium or high speed, the loader is slowed down by the bucket without the wheels being able to transmit a corresponding deceleration to the electric motor. As a result, the wheels spin in this situation, leading to the wheel loader digging itself in unintentionally.

[0015] It is an object of the invention to propose an improved method for operating an electric drive train of a working machine.

[0016] This problem is solved according to the invention by the method for operating an electric drive train of a working machine according to claim 1. Advantageous embodiments and further developments of the invention are described in the dependent claims.

[0017] The invention relates to a method for operating an electric drive train of a working machine, wherein the drive train comprises a working drive with an electric working motor and a driving drive with an electric driving motor and vehicle wheels, wherein the working machine experiences an external deceleration and wherein a braking force acting on the vehicle wheels due to the deceleration may be less than a driving force acting on the vehicle wheels due to a moment of inertia of the driving motor. The method according to the invention is characterized in that the driving motor is supplied with a current opposite to its direction of operation to reduce its speed when, by means of situation detection, it is predictably recognized that the braking force acting on the vehicle wheels due to the deceleration is less than the driving force acting on the vehicle wheels.

[0018] The invention describes a method relating to the operation of an electric drive train of a machine, wherein the drive train consists of at least two independently operable drives, namely the power drive and the travel drive. It is conceivable and preferred that the drive train also includes further elements or drives, for example, power take-offs or auxiliary drives. In particular, the drive train also includes an electrical energy storage device, preferably designed as a rechargeable electric battery. Advantageously, both the power drive and the travel drive each comprise one or more electric motors, which are used as travel motors or power motors, respectively, according to their configuration. They can additionally include transmissions or gear stages, outputs, hydraulic components, control electronics, and power electronics.A particularly advantageous feature of the electric motors is that they are identical in design for both the drive system and the working drive. This allows for cost-reducing economies of scale with regard to the electric motors. The drive system also includes vehicle wheels, which are driven by the drive motor and are rigidly connected to it or can be rigidly connected via a coupling. Similarly, the working drive includes a working attachment, such as a bucket or a lifting mast, which is driven by the working motor.

[0019] In certain operating situations, the machine may experience an external deceleration. For the purposes of this invention, this refers to a deceleration that is not initiated by the vehicle's brakes or drive system. Instead, the deceleration arises from the interaction of the machine with an external condition. For example, this could involve driving uphill on a steep incline or a working attachment of the machine becoming embedded in soil or scree. Both of these situations result in the machine experiencing an external deceleration without any input from the operator, and in particular without a braking request from the operator.

[0020] Particularly when the machine is decelerating and initially traveling at a relatively high speed, and the drive motor is therefore operating at a relatively high rotational speed, the braking force acting on the drive motor via the vehicle wheels may be less than the driving force acting on the vehicle wheels due to the drive motor's moment of inertia. Since the drive motor is an electric motor, it has a relatively large moment of inertia, which counteracts a reduction in rotational speed during deceleration. Because of this moment of inertia and the rotational speed of the electric motor, a driving force continues to act on the vehicle wheels, even when the drive motor is no longer being powered.The braking force acting on the vehicle wheels due to deceleration is largely determined by the wheels' ability to transmit force to the ground, i.e., by the traction force of the wheels on the respective surface. If the driving force becomes greater than the braking force also acting on the vehicle wheels, the wheels lose traction and spin. In other words, the vehicle wheels cannot reduce their rotational speed to the same extent as the machine reduces its speed. This can lead to the machine becoming undesirably digging into the ground.

[0021] For example, a wheel loader might be traveling at a relatively high speed when it inserts a bucket into a pile of earth. As the bucket enters the pile, the machine experiences a deceleration. This relatively high speed is necessary to drive the bucket as far into the earth as possible. However, the traction of the vehicle's wheels may not be sufficient to reduce the motor speed at the same rate as the machine's speed decreases. Consequently, the driving force acting on the wheels exceeds the braking force, causing them to spin. This can dig the wheel loader in and make it difficult to reverse the loader and extricate the bucket from the earth.

[0022] According to the invention, a situation detection system is therefore provided, which allows for the predictive detection of whether an externally applied deceleration is imminent or has already begun, and whether the resulting braking force acting on the vehicle wheels will be less than the driving force acting on the vehicle wheels due to the moment of inertia of the continuing-rotating drive motor. The situation detection system can, for example, predictively recognize that such a situation exists based on the onset of a deceleration of the machine's speed without a corresponding control input from the operator. To advantageously prevent wheel spin and thus undesirable digging of the machine, the drive motor is energized in the opposite direction to its current operating direction, according to the invention, in order to provide an additional braking torque acting on the drive motor.

[0023] According to a preferred embodiment of the invention, situation detection is achieved using environmental sensors. Suitable environmental sensors can be, in particular, camera sensors, radar sensors, or lidar sensors. For example, environmental sensors, especially in conjunction with appropriate sensor data evaluation, enable the detection of situations in which the machine experiences an external deceleration. For example, it can be detected that a wheel loader is approaching a pile of rubble in order to lower its bucket into it. Upon reaching the rubble pile and thus upon the onset of the deceleration, the rotational speed of the drive motor can be actively reduced by applying current in the opposite direction to the direction of rotation of the drive motor.

[0024] According to a further preferred embodiment of the invention, situation detection is achieved using acceleration sensors and / or tilt sensors. For example, the acceleration sensors can detect when the machine experiences a deceleration without a corresponding control input from an operator, indicating that this deceleration must be caused by an external factor. The tilt sensors can support situation detection using the acceleration sensors by, for example, detecting a steep incline as the cause of the external deceleration or the machine's rear axle rising as a result of a bucket entering a mound of earth.

[0025] According to a further preferred embodiment of the invention, situation detection is achieved by means of a slipping clutch, wherein a clutch pressure is specified such that the torque transmissible by the clutch is less than the braking torque resulting from the braking force. The braking torque at the vehicle wheels is the maximum possible braking torque resulting from the vehicle wheels' traction. Thus, with a slipping clutch, it can be detected that a driving force continues to act on the vehicle wheels, which are being braked externally.

[0026] The clutch pressure is preferably set such that normal operation of the machine is not impaired. Particularly preferably, the clutch pressure can also be reduced only after the machine has started moving, such that the torque transmissible by the clutch is less than the maximum braking torque at the vehicle wheels resulting from the vehicle's traction during an externally applied deceleration.

[0027] According to a further preferred embodiment of the invention, situation detection is achieved by means of speed and / or torque monitoring of the drive system. For example, if the speed of the drive system decreases and the torque increases simultaneously, particularly in the absence of a corresponding control input from the operator, the presence of an externally acting deceleration can be detected. If the torque simultaneously exceeds a predefinable threshold, the drive motor can be actively energized in the opposite direction of rotation to prevent wheel spin. Situation detection is also preferably achieved by monitoring a speed gradient and / or a torque gradient in the drive system.

[0028] Situation detection is also particularly preferably achieved by monitoring wheel slip. In the event of a sudden increase in slip at all vehicle wheels, especially in combination with one or more of the aforementioned preferred embodiments of situation detection, it can, for example, also be detected that the braking force acting on the vehicle wheels due to the deceleration is less than the driving force acting on the vehicle wheels. Wheel slip is preferably determined using the existing ABS sensors.

[0029] According to a further preferred embodiment of the invention, situation detection is carried out by means of absolute speed monitoring. Absolute speed monitoring involves monitoring the so-called "speed over ground." If the detected absolute speed decreases more sharply than the speed of the working machine determined via the wheel rotation, it can also be recognized in this case that the braking force acting on the vehicle wheels due to the speed deceleration is less than the driving force acting on the vehicle wheels.

[0030] According to a further preferred embodiment of the invention, situation detection is achieved by monitoring the power demand of the drive system. For example, the operator's activation of maximum drive motor power, i.e., a so-called "kickdown," particularly in conjunction with a subsequent deceleration of the machine's speed, can indicate that the operator intended to gain sufficient momentum through the kickdown and requires high torque to, for example, drive the bucket of a wheel loader as deeply as possible into a pile of earth. The subsequent deceleration signals that the pile of earth has been reached and the bucket has been retracted.

[0031] According to a further preferred embodiment of the invention, situation detection is achieved by monitoring the behavior of the working drive. The behavior of the working drive can include a pressure change in a working hydraulic system, as well as the alignment or positioning of a bucket on a bucket arm, the position of a lifting mast, or simply a control input from the operator, e.g., at a control element associated with the working drive, such as a joystick.

[0032] According to a further preferred embodiment of the invention, situation detection is achieved by monitoring the driving behavior of an operator of the machine, whereby the operator's driving behavior is learned beforehand when a deceleration is imminent. Thus, by observing the operator's driving behavior and by determining whether a specific driving behavior is typically followed by an external deceleration, it is advantageously recognized whether an externally acting deceleration is imminent.

[0033] Driving behavior can include, for example, acceleration profiles, speed profiles, control inputs, and steering angles.

[0034] It is particularly advantageous not to learn the driving behavior of just one operator, but rather to differentiate between several different operators of the machine based on their varying driving styles and to perform situational analysis for each operator by monitoring their driving behavior. Different operators can also be distinguished, for example, by their weight when they sit in the machine's driver's seat. For this purpose, a weight detection device can be integrated into the driver's seat.

[0035] Preferably, the situation assessment is additionally carried out by monitoring the currently engaged gear of a drive transmission, the status of a differential lock, the temperature of the drive motor or working motor, and GPS position information. The gear selection can, for example, be recorded as part of the driving behavior, as can the differential lock and the temperatures of the drive motor or working motor. The GPS position information can, for example, be used to detect the approach of the machine to a mound of earth whose GPS position is known.

[0036] According to a further preferred embodiment of the invention, the reduction in the speed of the drive motor is supported by downshifting. Downshifting changes the speed ratio between the drive motor and the vehicle wheels such that an identical speed of the vehicle wheels now corresponds to a higher speed of the drive motor, or conversely, an identical speed of the drive motor corresponds to a reduced speed of the vehicle wheels. Thus, unwanted digging of the machine can be slowed down, at least by the reduced speed of the vehicle wheels, until the speed of the drive motor can be reduced by applying current in the opposite direction of rotation to such an extent that the vehicle wheels no longer spin.

[0037] The invention further relates to an electric drive train for a working machine, wherein the drive train comprises a working drive with an electric working motor and a driving drive with an electric driving motor and vehicle wheels, wherein the vehicle wheels are rigidly coupled or can be coupled to the driving motor, so that in the event of an external deceleration of speed on the working machine, a braking force acting on the vehicle wheels is exerted by the deceleration of speed.The drive train according to the invention is characterized in that the drive train is designed to proactively detect, by means of situation detection, whether the braking force acting on the vehicle wheels due to the speed deceleration is less than a driving force acting on the vehicle wheels due to a moment of inertia of the drive motor, wherein the drive is designed to supply the drive motor with a current opposite to its operating direction in order to reduce the speed, when it is detected that the braking force is less than the driving force.

[0038] The drive train according to the invention thus enables the execution of the method according to the invention, which leads to the advantages already described in connection with the method according to the invention.

[0039] Preferably, the drive train further comprises an inverter for controlling the traction motor. The inverter is advantageously designed to execute not only the actual control of the traction motor but also the method according to the invention in the form of an electronically executable software algorithm. This results in the advantage of a comparatively very high control speed, since the inverter directly controls the traction motor.

[0040] The invention further relates to a working machine comprising a drive train according to the invention. The advantages already described in connection with the drive train according to the invention also apply to the working machine according to the invention.

[0041] According to a preferred embodiment of the invention, the working machine is designed as a wheel loader.

[0042] The invention is explained below by way of example with reference to embodiments shown in the figures.

[0043] They show: Fig. 1. An exemplary embodiment of a method according to the invention for operating an electric drive train of a working machine is shown in the form of a functional diagram and Fig. 2. An exemplary and schematic representation of a possible design form of a working machine according to the invention.

[0044] Identical objects, functional units, and comparable components are designated across all figures using the same reference symbols. These objects, functional units, and comparable components are identical in their technical characteristics unless explicitly or implicitly stated otherwise in the description.

[0045] Fig. Figure 1 shows an exemplary embodiment of a method according to the invention for operating an electric drive train 11 of a working machine 10 in the form of a functional diagram. The drive train 11 comprises a working drive 20 with an electric working motor 21 and a driving drive 30 with an electric driving motor 31 and vehicle wheels 32. If the working machine 10 experiences an external deceleration, the braking force acting on the vehicle wheels 32 due to the deceleration may be less than the driving force acting on the vehicle wheels 32 due to the moment of inertia of the driving motor 31. In such a situation, the vehicle wheels 32 may rotate at a speed higher than the actual speed of the working machine 10. The vehicle wheels 32 thus spin freely, leading to the working machine 10 becoming undesirably bogged down.To avoid this, a situation detection according to the invention is first carried out, as illustrated by functional block 100. Functional block 100 comprises a series of sub-blocks 101-113, each of which describes a specific type of situation detection. In block 101, the situation detection is carried out by means of speed monitoring of a driven axle of the working machine 10. Block 102 represents the situation detection by means of monitoring tire slip of the driven vehicle wheels 32. Block 103 describes the situation detection by means of monitoring a steering angle, and block 104 by means of monitoring hydraulic pressure in the working drive 20. Block 105 represents the situation detection by means of environmental sensors 12, for example by means of a camera sensor, and block 106 represents the situation detection by means of acceleration sensors.Block 107 represents situation detection by monitoring the output speed of a drive transmission 33 of the drive unit 30, and Block 108 represents situation detection by monitoring the selected gear stage of the drive transmission 33. Block 109 describes situation detection by monitoring the differential lock of a driven axle. Blocks 110, 111, and 112 describe situation detection by monitoring the actuation of an input device for the working drive 20, the position of a blade of the working drive 20, and the adjustment angle of a hydraulic pump of the working drive 20. Finally, in Block 113, situation detection is achieved by monitoring the drive motor 31 and the working motor 21, in particular the temperatures, speeds, torques, speed gradients, and torque gradients.In function block 200, the situational data acquired in function block 100 are automatically evaluated to predict whether a situation is imminent in which the braking force acting on the vehicle wheels 32 due to the deceleration is less than the driving force acting on the vehicle wheels 32, thus causing the vehicle wheels 32 to spin due to the external deceleration. If this is predictively detected, the speed of the traction motor 31 is actively reduced in function block 300. For this purpose, in sub-block 301, the traction motor 31 is supplied with current opposite to its operating direction to reduce its speed. Additionally, in block 302, a gear downshift is performed to support the rapid reduction in the speed of the traction motor 31.

[0046] Fig.Figure 2 shows an exemplary and schematic embodiment of a possible embodiment of a working machine 10 according to the invention. The working machine 10 is, for example, designed as a wheel loader 10 and comprises an electric drive train 11. The electric drive train 11, in turn, comprises a working drive 20 with an electric working motor 21 and a working device 22, as well as a travel drive 30 with an electric travel motor 31 and driven vehicle wheels 32. The vehicle wheels 32 can be rigidly coupled to the travel motor 31 via a travel transmission 33, so that when the speed of the wheel loader 10 is decelerated externally, a braking force acts on the travel motor 31. This braking force, however, is counteracted by a driving force generated by a moment of inertia of the travel motor 31 and acting on the vehicle wheels.If this driving force becomes greater than the braking force, the vehicle wheels 32 spin freely and dig in the wheel loader 10. The drive train 11 is therefore designed to execute the method according to the invention. Suitable environmental sensors 12 are used to detect the situation in order to predict whether the braking force acting on the drive motor 31 due to the deceleration is less than a driving force acting on the vehicle wheels 32 due to the moment of inertia of the drive motor 31. If this is the case, the drive motor 31 is supplied with a current opposite to its operating direction to reduce its speed. Reference sign 10 Work device 11 electric powertrain 12 Environmental sensors 20 Working drive 21 Working engine 22 Working device 30 Drive system 31 Drive motor 32 vehicle wheel 33 Driving transmission 100 Situation Assessment 101 Situation assessment using speed monitoring of a driven axle 102 Situation assessment by means of monitoring tire slippage of the driven vehicle wheels 103 Situation assessment by monitoring a steering angle 104 Situation assessment by means of monitoring hydraulic pressure in the working drive 105 Situation assessment using environmental sensors 106 Situation detection using acceleration sensors 107 Situation detection by means of monitoring the output speed of a drive transmission 108 Situation detection by means of monitoring an engaged gear stage of the drive transmission 109 Situation assessment by means of monitoring a differential lock 110 Situation detection by means of monitoring the activation of an input device for the work drive 111 Situation assessment using the position of a bucket of the working drive 112 Situation assessment using an adjustment angle of a hydraulic pump of the working drive 113 Situation assessment by means of monitoring the drive motor and the working motor 200 Situation assessment 300 Reduction of the speed of the drive motor 301 Powering the drive motor to reduce speed 302 Downshifting to support the reduction of the drive motor's speed

Claims

[1] Method for operating an electric drive train (11) of a working machine (10), wherein the drive train (11) comprises a working drive (20) with an electric working motor (21) and a driving drive (30) with an electric driving motor (31) and vehicle wheels (32), wherein the working machine (10) experiences an external deceleration and wherein a braking force acting on the vehicle wheels (32) due to the deceleration may be less than a driving force acting on the vehicle wheels (32) due to a moment of inertia of the driving motor (31), characterized by , that the traction motor (31) is supplied with a current opposite to its operating direction to reduce the speed (300, 301) when, by means of situation detection, it is predictably recognized that the braking force acting on the vehicle wheels (32) due to the deceleration of speed is less than the driving force (200) acting on the vehicle wheels (32). [2] Method according to claim 1, characterized by , that the situation is detected using environmental sensors (12) (105). [3] Method according to at least one of claims 1 and 2, characterized by that the situation is detected using acceleration sensors and / or tilt sensors. [4] Method according to at least one of claims 1 to 3, characterized by , that the situation detection is carried out by means of a slipping clutch, whereby a clutch pressure is specified such that a torque that can be transmitted by the clutch is less than a braking torque resulting from the braking force. [5] Method according to at least one of claims 1 to 4, characterized by , that the situation detection is carried out by means of speed monitoring and / or torque monitoring of the drive system (30) (113). [6] Method according to at least one of claims 1 to 5, characterized bythat the situation is assessed by means of absolute speed monitoring. [7] Method according to at least one of claims 1 to 6, characterized by , that the situation detection is carried out by means of monitoring a power request of the drive system (30) (113). [8] Method according to at least one of claims 1 to 7, characterized by , that the situation assessment is carried out by means of monitoring a behavior of the work drive (20) (104,110, 111, 112). [9] Method according to at least one of claims 1 to 8, characterized by , that the situation detection is carried out by means of monitoring the driving behavior of an operator of the working machine (10), whereby the driving behavior of the operator of the working machine (10) is learned beforehand when the speed deceleration is imminent. [10] Method according to at least one of claims 1 to 9, characterized by, that the speed reduction of the drive motor (31) is supported by downshifting (300, 302). [11] Electric drive train (11) for a working machine (10), wherein the drive train (11) comprises a working drive (20) with an electric working motor (21) and a driving drive (30) with an electric driving motor (31) and vehicle wheels (32), wherein the vehicle wheels (32) are rigidly coupled or can be coupled to the driving motor (31) so that in the event of an external deceleration of speed on the working machine (10) there is a braking force acting on the vehicle wheels (32) due to the deceleration of speed, characterized by, that the drive train (11) is designed to proactively detect, by means of situation detection, whether the braking force acting on the vehicle wheels (32) due to the speed deceleration is less than a driving force acting on the vehicle wheels (32) due to a moment of inertia of the drive motor (31), wherein the drive system (30) is designed to supply the drive motor (30) with a current opposite to its operating direction in order to reduce the speed, when it is detected that the braking force is less than the driving force. [12] Drive train (11) according to claim 11, characterized by , that the drive train (11) is configured to perform a method according to at least one of claims 1 to 9. [13] Working machine (10) comprising a drive train (11) according to at least one of claims 11 and 12. [14] Working machine (10) according to claim 13, characterized by, that the working machine (10) is designed as a wheel loader (10).

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