Method and control arrangement for the transfer of power between electrical machines in a vehicle

Abstract

A method performed by a control arrangement for the propulsion of a vehicle, wherein the vehicle comprises at least one first electric machine configured to supply power to a first vehicle wheel and at least one second electric machine configured to supply power to a second vehicle wheel. The at least one first electric machine and the at least one second electric machine in the vehicle are connected to each other by means of a hydraulic connection, which enables the utilization of the available power of the electric machines by transferring excess power supplied by one or more electric machines to a drive wheel or axle where additional power is required. This allows for improved vehicle performance. The invention also relates to a control arrangement, a vehicle comprising the control arrangement, a computer program and a computer-readable medium.

Description

Technical area

[0001] The invention relates to a method and a control arrangement for transmitting power between electrical machines in a vehicle. The invention also relates to a computer program and a computer-readable medium, as well as to a vehicle having such a control arrangement. background

[0002] The following background description provides a description of the background of the invention, but does not necessarily constitute prior art.

[0003] A vehicle must be able to drive safely and reliably under varying road conditions.

[0004] Some electric vehicles, such as trucks and buses, are equipped with separate drivetrains, which can offer certain advantages, such as improved traction, better maneuverability, and greater flexibility in power distribution. Because they have a separate drivetrain, power can be sent independently to each axle or wheel of the vehicle, allowing for better traction control and optimized power delivery to the wheels with traction. This setup can also improve the vehicle's maneuverability, as power can be selectively distributed to specific wheels or axles, enabling better drivability in different driving situations. Furthermore, separate drivetrains offer flexibility in power distribution, allowing adjustments to be made to varying road conditions and driving requirements. Summary

[0005] An object of the present invention is to provide methods and control arrangements that mitigate or eliminate the disadvantages of conventional solutions.

[0006] According to a first aspect of the invention, the above-described and further objects are achieved by a method for driving a vehicle, wherein the vehicle comprises at least one first electric machine configured to provide power to a first vehicle wheel and at least one second electric machine configured to provide power to a second vehicle wheel, wherein the at least one first electric machine and the at least one second electric machine are connected to one another by means of a hydraulic connection, wherein the method comprises for at least one vehicle driving condition: Transferring power between the at least one first electric machine and the at least one second electric machine by means of the hydraulic connection.

[0007] It will be appreciated that, depending on the vehicle configuration, the at least one first electric machine and the at least one second electric machine may be used to provide power to one or more vehicle drive wheels and / or to one or more power consumers in the vehicle, as described below. The at least one vehicle driving condition may be a condition indicating that excess power is available in one or more electric machines and, at the same time, additional power is required to operate the vehicle to achieve a required performance capability. The vehicle driving condition may, for example, be a condition indicating that additional power is required to propel the vehicle according to a certain required speed. The additional power may be motive power or braking power.For example, the maximum power that can be provided by an electric machine at a first vehicle drive wheel or a first vehicle axle may not be sufficient to start the vehicle or to operate the vehicle at a required speed when such a driving condition exists. At the same time, excess power may be available in another electric machine, e.g., an electric machine driving a second vehicle drive wheel, which has limited power, e.g., because it is on a low-friction road surface. The vehicle driving condition may, for example, relate to an inclined road section, a slippery road section, or uneven loading of the vehicle drive wheels.

[0008] Conventionally, when the vehicle is powered by a single electric machine or a plurality of mechanically interconnected electric machines, and such a driving condition is detected, the supplied power can be redistributed between the vehicle's wheels or axles to improve vehicle performance. However, in configurations where such a mechanical connection between the electric machines does not exist, for example, in vehicles with more than one driven axle driven by separate drive units, the vehicle's maximum power may not be utilized, resulting in degraded vehicle performance.

[0009] According to the invention, the electric machines in the vehicle are connected to each other via a hydraulic connection, which makes it possible to utilize the available power of the hydraulically interconnected electric machines by transferring excess power provided by one or more electric machines to a drive wheel or axle where additional power is required. This allows for improved vehicle performance.

[0010] In one embodiment of the invention, the vehicle driving state occurs when the road grip of the first vehicle wheel differs from the road grip of the second vehicle wheel, the method further comprising: Transferring power from the at least one first electric machine to the at least one second electric machine when the road grip of the second vehicle wheel exceeds the road grip of the first vehicle wheel, and vice versa.

[0011] The roadholding of a vehicle's wheel is a measure of how well the wheel maintains contact with the road surface while moving. Wheel grip is critical to a vehicle's performance, as it directly affects its ability to accelerate, decelerate, and maneuver effectively. When a wheel has good roadholding, it means it can maintain traction with the surface to such an extent that it can transmit the necessary forces for propulsion, braking, and steering.

[0012] Factors that can affect road grip include the nature of the surface, such as rough, smooth, dry, wet, etc., the condition of the wheel, i.e. tire quality, tread depth, tire pressure and external forces acting on the wheel, e.g. the load of the vehicle.

[0013] Uneven road grip on the vehicle's wheels can occur, for example, if the factors described above vary for different wheels. For example, the load on the vehicle's wheels may be uneven, or parts of the road surface on which the vehicle is traveling may be slippery. Such uneven road grip on the vehicle's wheels can affect the vehicle's handling, performance, and safety.

[0014] Potential consequences of uneven road grip include reduced traction at certain wheels, which can lead to reduced acceleration and braking performance. Furthermore, wheels with better grip may experience excessive wear, while wheels with poor grip may experience less wear. This can lead to premature tire replacement and can also affect the overall balance of the vehicle.

[0015] By transferring power from the at least one first electric machine to the at least one second electric machine when the road grip of the second vehicle wheel exceeds the road grip of the first vehicle wheel, and vice versa, more power is transferred to the wheel with better road grip. This optimizes the vehicle's power consumption by minimizing unnecessary wheel slip or spin. This can lead to improved energy efficiency and a longer electric range in hybrid or electric vehicles.

[0016] Furthermore, the vehicle can be dimensioned with smaller electric motors compared to conventional powertrain configurations. This is because the invention enables more precise control of the distribution of the total power in the vehicle to the individual wheels / axles, which can compensate for the lower power output of smaller electric motors. This can contribute to cost savings in vehicle manufacturing and reduce the overall vehicle weight. Lighter vehicles often have better power efficiency and drivability. Likewise, they can require less power to operate, which can increase the vehicle's range.

[0017] In one embodiment of the invention, the first vehicle wheel and the second vehicle wheel are arranged on a common vehicle axle.

[0018] This means that the power generated by the at least one first electric machine and the at least one second electric machine can be distributed between the wheels of the same axle in such a way that more power is delivered to the wheel with higher grip to maximize traction. By delivering more power to the wheels with higher grip or those requiring more power, the stability and performance of the vehicle can be improved, particularly in difficult road conditions, such as wet or slippery surfaces. This can increase driving safety and confidence in the vehicle.

[0019] In one embodiment of the invention, the first vehicle wheel is a wheel of a first vehicle axle of the vehicle, and the second vehicle wheel is a wheel of a second vehicle axle.

[0020] It can be seen that the first and second vehicle axles connect and support the wheels on opposite sides of a vehicle. There are different types of axles used in vehicles, depending on the vehicle's configuration. For example, the first and second vehicle axles can be a vehicle axle, such as a front axle that supports the vehicle's front wheels, a rear axle that supports the vehicle's rear wheels, an axle on a trailing vehicle, a retractable vehicle axle, and / or a driven electric axle that receives torque from one or more electric machines in the vehicle.

[0021] This means that the power generated by the at least one first electric machine and the at least one second electric machine can be distributed to different axles of the vehicle in order to improve the stability and performance of the vehicle.

[0022] In one embodiment of the invention, the first vehicle axle is mechanically separated from the second vehicle axle.

[0023] Since the first vehicle axle is mechanically separated from the second vehicle, no power can be mechanically transferred between the first vehicle axle and the second vehicle axle. Conventional torque distribution between different axles is therefore not possible. The invention makes it possible to distribute the power generated by the at least one first electric machine and the at least one second electric machine between different vehicle axles. This improves the stability and performance of the vehicle, even in vehicle configurations where such distribution would otherwise not be possible.

[0024] In one embodiment of the invention, the at least one first electrical machine is mechanically separated from the at least one second electrical machine.

[0025] It can be seen that the at least one first electrical machine is mechanically separated from the at least one second electrical machine such that no power can be mechanically transmitted between the separated electrical machines.

[0026] The invention makes it possible to distribute the power generated by the at least one first electric machine and the at least one second electric machine between different vehicle wheels and / or axles without a mechanical connection for power transmission. This improves the stability and performance of the vehicle, even in vehicle configurations where such distribution would otherwise not be possible.

[0027] In one embodiment of the invention, the at least one first electric machine and / or the at least one second electric machine are / is configured to drive a power take-off (PTO) by means of a hydraulically connected power take-off, and wherein the vehicle driving condition includes a power take-off request, the method further comprising: Transferring the power from the at least one first electric machine or the at least one second electric machine to the hydraulically connected power take-off.

[0028] This means that a power take-off can be driven by any of the vehicle's electrical machines that have excess power. This enables efficient, flexible, and reliable power supply to the power take-off.

[0029] In one embodiment of the invention, the magnitude of the power transmitted by the at least one first electric machine and / or the at least one second electric machine via the hydraulic connection is based on one or more parameters related to the vehicle driving condition.

[0030] In this way, the power generated in the at least one first electrical machine and the at least one second electrical machine can be managed efficiently and reliably.

[0031] In one embodiment of the invention, the parameters related to the vehicle driving state include: - a rotational speed of the at least one first electrical machine and / or the at least one second electrical machine, - wheel slip of the first vehicle wheel and / or the second vehicle wheel, - a weight of the vehicle, - a slope of an approaching road section, - a rate or rate of change of an acceleration requirement, - an available power that can be transferred between the vehicle and the road, - a vehicle driving mode, - a road condition for the upcoming road section, - a vehicle steering angle, - a load on the vehicle axles of the vehicle, and / or - a power request to a power take-off connected to the at least one first electric machine and / or the at least one second electric machine.

[0032] Such parameters, i.e., vehicle-related parameters and / or parameters related to the approaching road section, can be determined in the vehicle using conventional solutions. This allows the occurrence of the vehicle's driving state to be determined efficiently and reliably.

[0033] In one embodiment of the invention, the method further comprises: Disconnecting the at least one first electric machine from the first vehicle wheel and / or the at least one second electric machine from the second vehicle wheel prior to transferring power from the disconnected electric machine via the hydraulic connection.

[0034] This allows the excess power from an electric machine to be efficiently transferred even when no power is to be transferred to the vehicle wheel for which the electric machine is configured to supply power.

[0035] In one embodiment of the invention, one or both of the at least one first and at least one second electric machines are configured to drive a hydraulic pump to supply hydraulic fluid to a hydraulic motor connected to the wheel driven by the other of the at least one first and at least one second electric machines, to thereby transfer power from one of the at least one first and at least one second electric machines to the other.

[0036] The power can be transmitted from or to one or both of the at least one first and at least one second electric machine by means of the hydraulic connection.

[0037] According to a second aspect, the invention relates to a control arrangement for supplying power to a vehicle, wherein the vehicle comprises at least one first electric machine configured to provide power to a first vehicle wheel and at least one second electric machine configured to provide power to a second vehicle wheel, wherein the at least one first electric machine and the at least one second electric machine are connected to one another by means of a hydraulic connection, wherein the control arrangement is configured to, for at least one vehicle driving condition: to transmit power between the at least one first electric machine and the at least one second electric machine by means of the hydraulic connection.

[0038] It is evident that all embodiments described for the method aspects of the invention are also applicable to at least one aspect of the control arrangement of the invention. Thus, all embodiments described for the method aspects of the invention can be carried out by the control arrangement, which can also be a control device, ie, a device. The control arrangement and its embodiments have advantages that correspond to the advantages described above for the methods and their embodiments.

[0039] According to a third embodiment of the invention, the described and further objects are achieved by a vehicle having the control arrangement of the second aspect.

[0040] According to a fourth aspect, the invention relates to a computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method according to the first aspect.

[0041] According to a fifth aspect, the invention relates to a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to the first aspect. Brief description of the drawings

[0042] Embodiments of the invention are described in more detail below together with the accompanying drawings, in which similar references are used for similar parts. In the drawings: Fig. 1a shows an exemplary vehicle in which embodiments of the invention can be implemented; Fig. 1b shows a vehicle configuration in which embodiments of the invention can be implemented; Fig. 1c shows another vehicle configuration in which embodiments of the invention can be implemented; Fig. 2a is a flowchart of a method for controlling an electric drive train of a vehicle in the freewheeling state according to embodiments of the invention; Fig. 2b shows a flowchart of a method for controlling an electric drive train of a vehicle in the freewheeling state according to further embodiments of the invention; Fig. 3 shows an example of power transmission between electrical machines in a vehicle according to embodiments of the invention; Fig. 4a shows an example of the actuation of the power transmission based on the slip difference of the vehicle drive wheels according to embodiments of the invention; Fig. 4b shows an example of the actuation of the power transmission based on the speed difference of the electric machines in a vehicle according to embodiments of the invention; and Fig. 5 a control arrangement in which a method according to one of the embodiments described here can be carried out. Detailed description

[0043] In electric vehicles, it is generally advantageous to be able to distribute the power generated within the vehicle to avoid costly over-sizing of the vehicle's power supply. For example, if a wheel or axle has no or very low grip, it would be desirable in certain cases to transfer more power to the wheel or axle that does. In applications where grip is sometimes limited, torque can be distributed to the wheel or axle with the greatest grip by using differential locks (“difflocks”), torque vectoring, or individual wheel braking. In a vehicle with more than one driven axle, a cross-axle differential lock is often used to transfer power to all wheels and thus maximize tractive effort.

[0044] For electric vehicles powered by separate electric motors, it is sometimes not possible to utilize the vehicle's maximum propulsion power. If an axle lacks friction, the electric motor supplying power to that axle has no way to transfer the power to an axle or wheel with higher traction unless there is a mechanical connection between that electric motor and the axle or wheel with higher traction. The ability to provide such a mechanical connection for power transfer is sometimes limited by factors such as a large axle spacing, lack of space in the vehicle chassis, or other constraints on the axle configuration.

[0045] Therefore, it is an object of the present invention to provide a method and a control arrangement for driving a vehicle, with which these problems are at least partially solved.

[0046] Fig. 1a, which is used to describe the exemplary embodiments presented here, shows a vehicle 100. The vehicle 100 may be an electric vehicle, such as a truck or a bus. Although in Fig. 1a, the vehicle 100 may be equipped with a trailer. Alternatively, the vehicle may also be a passenger car. Fig. The vehicle 100 illustrated in Figure 1a may include a drivetrain 110a configured for an electric vehicle, for example, a battery-powered electric vehicle. The drivetrain may include an electric motor system including at least one first electric machine 101a and may be configured to apply drive power and / or regenerative power, e.g., to provide torque to one or more wheels 111a, 111b of the vehicle 100. It is apparent that the vehicle 100 may include fewer or more wheels than in Fig. 1a. The at least one first electric machine 101a can be connected in a conventional manner to at least one energy storage device B, which is configured to supply the at least one first electric machine 101a with electrical power.

[0047] The at least one first electric machine 101a can be arranged essentially at any location as long as a torque is transmitted to one or more wheels of the vehicle.

[0048] The at least one first electric machine 101a can, for example, be connected in a conventional manner via an output shaft 102 to a transmission 103 via a drive shaft of the transmission 103. A propeller shaft 104 connected to an output shaft of the transmission 103 drives the drive wheels 111a, 111a via a vehicle axle A1 connecting and supporting the drive wheels 111a, 111b of the vehicle 100. The vehicle axle A1 comprises a central transmission 105 and drive shafts 106a, 106b. The central transmission 105, such as a commercially available differential, is connected to the propeller shaft 104 and distributes the power to the drive shafts 106a, 106b. Power provided by the at least one first electric machine 101a is thus transmitted to the drive wheels 111a, 111b.It will be appreciated that vehicle 100 may be arranged in any known manner, for example, without a conventional differential and / or transmission, without limiting the scope of the invention. The vehicle may be configured with one or more drive axles, with each driven axle being separately powered by one or more electric machines.

[0049] Furthermore, the at least one first electric machine 101a can be arranged essentially at any location along the drive train 110a, as long as torque is provided for one or more of the wheels, e.g., configured as a wheel hub motor that is directly integrated into a vehicle wheel 111a, 111b and supplies it with power individually.

[0050] Furthermore, the vehicle may comprise at least one second electric machine 101b and / or be configured with at least one additional drive train comprising the at least one second electric machine 101b, as described with reference to the Fig. 1b and Fig. 1c is described.

[0051] The vehicle may further include a power take-off (PTO) 130 configured, when coupled to a power source, to transfer power from the power source to another device (not shown), as further described in this disclosure. The power source powering the PTO may be an electric machine, such as electric machine 101a described above, or another electric machine. The PTO may be driven via a hydraulic connection connecting the PTO to one or more electric machines.

[0052] The components of the drive train 110 of the vehicle 100 as well as other components of the vehicle 100 can be controlled by a vehicle control system via a control arrangement 120. The control arrangement 120 can be distributed among several control units configured to control different parts of the vehicle 100. The control arrangement 120 can, for example, comprise a unit 121 for transmitting power between at least one first electric machine and at least one second electric machine in the vehicle by means of the hydraulic connection, as well as further devices for carrying out the method steps of the disclosed invention, as will be described below. The control arrangement 120 is described in connection with Fig. 5 described in more detail.

[0053] The vehicle 100 may further include one or more sensors 140 that provide sensor data to the vehicle control system, e.g., sensors for measuring the weight of the vehicle 100, the speed of one or more electrical machines in the vehicle, the wheel slip of one or more wheels of the vehicle 100, to name a few. Furthermore, the vehicle 100 may include a positioning system / unit 150. The positioning unit 150 may be based on a satellite navigation system, such as Navstar (Navigation Signal Timing and Ranging), Global Positioning System (GPS), Differential GPS (DGPS), Galeo, GLONASS, or the like. The positioning unit 150 may thus include a GPS receiver.It will be appreciated that the above-described one or more sensors 140 and the positioning system / unit 150 may be configured to communicate with the control arrangement 120 to provide the control arrangement 120 with relevant information.

[0054] It is apparent that the vehicle 100 may comprise further units, components, such as electrical and / or mechanical components, which are Fig. 1a are not shown. The vehicle 100 may, for example, be configured and include means for communication with another external functional unit, e.g., by means of vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, or vehicle-to-everything (V2X) communication. In Fig. However, Figure 1a only shows the units / devices / functional units of the vehicle 100 required for understanding the present invention.

[0055] The proposed solution will now be discussed with reference to a Fig. 2a and the method 200 shown in Fig. The vehicle 100 shown in Figure 1a is described. Fig. 2a shows a flowchart of the method 200 for driving a vehicle 100, wherein the vehicle 100 comprises at least one first electric machine 101a configured to supply power to a first vehicle wheel 111a, and at least one second electric machine 101b configured to supply power to a second vehicle wheel 111a, 112a, 112b, wherein the at least one first electric machine 101a and the at least one second electric machine 101b are connected to one another by means of a hydraulic connection.

[0056] The method comprises, for at least one vehicle driving condition in step 210, transmitting power between the at least one first electric machine 101a and the at least one second electric machine 101b by means of the hydraulic connection.

[0057] By transferring the power between the electric machines 101a, 101b, the invention aims to increase the total power provided to the drive wheels of the vehicle during a driving condition when this total power is otherwise limited, as described with reference to Fig. 3 is described.

[0058] Fig. 3 shows an example of a power transfer between electrical machines in a vehicle 100 according to the method 200 of the invention. In the Fig. In the non-limiting example shown in Figure 3, power is transmitted between at least one first electric machine 101a that supplies power to a first driven axle A1 and / or to a first wheel, and at least one second electric machine 101b that supplies power to a second driven axle A2 and / or to a second wheel. Fig. 3 shows a graph P A1 , which corresponds to the power applied over time by the at least one first electric machine 101a, a graph P A2 , which corresponds to the power applied over time by the at least one second electric machine 101b, and a graph P SUM , which corresponds to the total power generated over time by the at least one first and the at least one second electrical machine 101a, 101b. In Fig. 3 so P SUM = P A1 + P A2 .

[0059] In addition, Fig. 3 the power P REQ which corresponds to the minimum total power required to drive or brake the vehicle 100. At the required minimum power P REQ For example, it may be a power required to overcome a total driving resistance and / or to maintain a certain speed profile, or a power required to start or brake the vehicle 100.

[0060] Furthermore, Fig. 3 the power limits P1 and P3, where P3 corresponds to the maximum power that may be applied to the wheel axle A1 and / or the first wheel, and P1 corresponds to the maximum power that may be applied to the wheel axle A2 and / or the second wheel during the current driving situation. The power limits P1 and P3 can be specified, for example, by the road friction of the current road section. In addition, Fig. 3 the maximum power P MAX which can be delivered by electrical machines to drive the vehicle 100. In the Fig. 3, the wheels of the first axle A1 and / or the first wheel may be located, for example, on a road surface with high friction, and the power P applied to the first vehicle axle A1 and / or the first wheel A1 therefore the maximum power P MAXthat can be generated by the at least one first electric machine 101a. The wheels of the second axle A2 and / or the second wheel, however, may be located on a road surface with low friction, which means that the power limit P1 is lower than the maximum power P MAX that could be generated by the at least one second electric machine 101b. If the power applied to a vehicle axle and / or wheel is higher than the power limit P1, the vehicle wheels are likely to spin, which may lead to an instability situation and increased power loss.

[0061] As in Fig. 3, the total power P generated by the at least one first and the at least one second electrical machine 101a, 101b between the times T0 and T1 is SUM less than P REQ, which means that the vehicle cannot be operated according to the requirements during the current vehicle driving state. If such a vehicle driving state is detected, according to the invention, a power transfer between the at least one first electric machine 101a and the at least one second electric machine 101b is carried out by means of a hydraulic connection. Thus, between time T1 and time T2, the at least one second electric machine 101b generates additional power, which is shown in the graph P A2 to the first vehicle axle A1. This results in the total power P SUMbetween time T1 and T2. At time T2, the sum of the power supplied to the vehicle, including the power transferred from the at least one second electric machine 101b to the at least one first electric machine 101a, overcomes the total driving resistance and reaches the required minimum power P REQ .

[0062] In other words, the invention may be applied to the vehicle 100 configured with two or more electric machines for driving and / or braking the vehicle 100, wherein the two or more electric machines are connected to each other by a hydraulic connection, as described below.

[0063] Such two or more electric machines may be configured in the vehicle 100 in different ways without limiting the scope of the invention. Fig. 1b - 1c show examples of vehicle configurations comprising two or more electric machines, ie the at least one first electric machine 101a and the at least one second electric machine 101b.

[0064] The at least one first electric machine 101a is, as described above, configured to provide power to a first vehicle wheel 111a, and the at least one second electric machine 101b is configured to provide drive or braking power to a second vehicle wheel.

[0065] Fig. 1b shows a vehicle configuration including a first electric machine 101a configured to supply power to the vehicle wheel 111a, which is the first vehicle wheel here. The vehicle further includes a second electric machine 101b configured to supply power to a second vehicle wheel 111b, which is the second vehicle wheel here. In one embodiment, the first vehicle wheel 111a and the second vehicle wheel 111b may be arranged on a common vehicle axle A1, as shown in Fig. 1b. In one embodiment, the first vehicle wheel 111a may be mechanically separated from the second vehicle wheel 111b.

[0066] In an embodiment, as in Fig. 1c, the first vehicle wheel 111a may instead be one or more wheels of a first vehicle axle A1 of the vehicle 100, and the second vehicle wheel 112a, 112b may be one or more wheels of a second vehicle axle A2. In one embodiment, the first vehicle axle A1 may be mechanically separated from the second vehicle axle A2.

[0067] In one embodiment, the at least one first electrical machine 101a may be mechanically separated from the at least one second electrical machine 101b.

[0068] As in the Fig. 1b - 1c, the at least one first electric machine 101a and the at least one second electric machine 101b may be interconnected by a hydraulic connection H. The hydraulic connection H may be used to transfer power between the interconnected electric machines. A hydraulic connection uses hydraulic fluid to transfer power from one electric machine to the other. As shown in the Fig. 1b-1c, the hydraulic connection may include at least one hydraulic pump 109a and at least one hydraulic motor 109b. In one embodiment, one or both of the at least one first and at least one second electric machines 101a, 101b may be configured to drive the hydraulic pump 109a to supply hydraulic fluid to the hydraulic motor 109b connected to the wheel driven by the other of the at least one first and at least one second electric machines, to thereby transfer power from one of the at least one first and at least one second electric machines to the other.

[0069] In one embodiment, the at least one first electric machine 111a and / or the at least one second electric machine 111b may be configured to drive a hydraulically connected power take-off 130, as shown in the Fig. 1b - 1c.

[0070] In addition to the method step 210 in Fig. 2a, the method 200 may include optional steps 202-208, as in Fig. 2b shown. Fig. 2b thus shows a flowchart of the method 200 according to further embodiments of the invention. It should be noted that the Fig. 2b and described here do not necessarily have to be carried out in the manner described in Fig. 2b. The steps can essentially be performed in any suitable order, as long as the physical conditions and the information required to perform each method step are available at the time the step is performed.

[0071] As already described, the method 200 according to the invention is carried out when at least one vehicle driving state has been detected. Thus, in an optional step 202 in Fig. 2b, which precedes the method step 210 described above, which detects at least one driving condition that leads to the execution of the method 200.

[0072] In one embodiment, the at least one vehicle driving condition leading to the execution of method 200 may occur when the road grip of the first vehicle wheel 111a deviates from the road grip of the second vehicle wheel 111a, 112a, 112b. If such a vehicle driving condition is detected, in step 210, the power may be transferred from the at least one first electric machine 101a to the at least one second electric machine 101b if the road grip of the second vehicle wheel 111b exceeds the road grip of the first vehicle wheel 111a, and vice versa. Such a vehicle driving condition may be detected according to conventional methods, for example, based on one or more parameters related to the vehicle driving condition and described further in this disclosure. An example of such a power transfer based on a parameter related to the vehicle driving condition is described in Fig. 4a and Fig. 4b.

[0073] The different road grip of the first vehicle wheel 111a compared to the road grip of the second vehicle wheel 111a, 112a, 112b can be determined based on a wheel slip of the first vehicle wheel 111a and / or the second vehicle wheel 111b, 112a, 112b, as in Fig. 4a, or based on the speed(s) of the at least one first electric machine 101a and / or the at least one second electric machine 101b, as shown in Fig. 4b. For example, the power transfer may occur when the difference in the wheel slip ratio of the drive wheels or the difference in the speeds of the electric machines reaches a certain threshold. Such a difference in the wheel slip ratio or in the speed of the electric machines may occur, for example, when the friction of the road surface of the first vehicle wheel differs from the friction of the road surface of the second vehicle wheel. In another example, such a difference may occur when the load on the vehicle axles or the vehicle wheels becomes uneven. The load between the vehicle axles or wheels may become uneven in various situations, e.g., when the load is unevenly distributed, when the vehicle is traveling on inclined or uneven road surfaces, during braking and acceleration, and when turning.In addition, the load between the axles or wheels of the vehicle may change when one or more axles are lifted.

[0074] Fig. 4a shows the power transfer over time between two electric machines, such as the at least one first electric machine 101a and the at least one second electric machine 101b, based on the difference in the wheel slip ratio of the drive wheels, such as the first vehicle wheel 111a and the second vehicle wheel 111b, 112a, 112b. As shown in the lower graph B in Fig. As can be seen in Figure 4a, the difference between the wheel slip of the vehicle's drive wheels increases between time T0 and time T1. At time T1, the difference in wheel slip reaches a slip threshold value S th . The size of the slip threshold S thmay depend on the application of the invention and may be available in the control system of the vehicle 100. As shown in the upper graph A, between the time T0 and T1, ie when the difference in vehicle slip is below the slip threshold S th no power transfer is carried out between the at least one first electric machine 101a and the at least one second electric machine 101b. However, if the slip threshold value S th is reached at time T1, power is transferred from the at least one first electric machine 101a to the at least one second electric machine 101b when the slip of the second vehicle wheel 111b, 112a, 112b exceeds the slip of the first vehicle wheel 111a, and vice versa. The slip threshold value S th For example, a value can be greater than 0% and less than 10%.

[0075] Similarly, Fig. 4b illustrates a temporal power transfer between two electric machines, such as the at least one first electric machine 101a and the at least one second electric machine 101b, based on the difference in the rotational speed(s) of the at least one first electric machine 101a and / or the at least one second electric machine 101b. It will be appreciated that when determining whether there is a difference in the rotational speeds of the electric machines 101a, 101b, any difference in the gear ratios applied to the at least one first electric machine 101a and the at least one second electric machine 101b must be taken into account.If different gear ratios are applied to the electric machines 101a, 101b, the speed(s) of the at least one first electric machine 101a and / or the at least one second electric machine 101b must be compensated with the gear ratio difference before the speed difference is determined.

[0076] As shown in the lower graph D in Fig. As can be seen in Figure 4b, the difference between the rotational speed of the at least one first electric machine 101a and the at least one second electric machine 101b increases between time T0 and time T1. At time T1, the difference between the rotational speed of the at least one first electric machine 101a and the at least one second electric machine 101b reaches a rotational speed threshold value ω TH . The magnitude of the speed threshold ω THmay depend on the application of the invention and be available in the control system of the vehicle 100. As shown in the upper graph C, between the time T0 and T1, ie when the difference between the speed of the at least one first electric machine 101a and that of the at least one second electric machine 101b is below the speed threshold ω TH no power transfer is carried out between the at least one first electric machine 101a and the at least one second electric machine 101b. However, if the speed threshold value ω TH at time T1, a power transfer takes place from the at least one first electric machine 101a to the at least one second electric machine 101b when the road grip of the second vehicle wheel 111b, 112a, 112b exceeds the road grip of the first vehicle wheel 111a, and vice versa. The speed threshold value ω THFor example, a value can be greater than 0% and less than 10%.

[0077] By transferring the power between the vehicle wheels, the slip difference of the vehicle is kept below the slip threshold S th maintained and the power acting on the vehicle increased.

[0078] In one embodiment, the vehicle driving condition may include a power take-off request when the at least one first electric machine 111a and / or the at least one second electric machine 111b are configured to drive a hydraulically connected power take-off 130. When such a power take-off request is detected, power may be transferred from the at least one first electric machine 111a or the at least one second electric machine 111b to the hydraulically connected power take-off 130.

[0079] A power take-off is used to transfer power from a power source, such as an electrical machine, to another device, such as an auxiliary load, which consumes energy in response to a power request. The power take-off power request may relate to the activation of the power take-off and may be manual, e.g., when the power take-off is manually activated by the vehicle operator via a lever or switch, or automatic, e.g., based on a control algorithm in the vehicle, depending on the specific application. For example, if the auxiliary load is the compressor of a refrigeration unit, the power take-off may be automatically activated based on the temperature of the refrigeration unit. Such a power take-off power request may be detected by or communicated to the control arrangement 120 using conventional methods.

[0080] In step 204 in Fig. 2b, the magnitude of the power to be transmitted via the hydraulic connection is determined. In one embodiment, the magnitude of the power transmitted by the at least one first electric machine 101a and / or the at least one second electric machine 101b via the hydraulic connection may be based on one or more parameters related to the vehicle driving condition. The magnitude of the power to be transmitted via the hydraulics may, for example, be determined based on the power required to propel or decelerate the vehicle 100 on the approaching road section according to a required vehicle speed. The required vehicle speed may, for example, be based on a rate or a rate of change of an acceleration request.The power required to propel or decelerate the vehicle 100 on the approaching road section can be predicted based on Newton's laws of motion, taking into account the forces acting on the vehicle 100 in an approaching road section when driven at the required speed. According to conventional solutions, the forces may depend on parameters such as the vehicle weight, a vehicle steering angle, information about the road condition of the approaching road section, and information about the road topology, such as the gradient of the approaching road section. Furthermore, the amount of power to be transmitted via the hydraulic connection may be based on the available power that can be transmitted between the vehicle and the road, i.e.on the maximum power that can be delivered by the at least one first electric machine 101a and the at least one second electric machine 101b. Furthermore, the power to be transmitted via the hydraulic connection may depend on the driving mode of the vehicle.

[0081] If the power transmitted via the hydraulic connection drives a hydraulically connected power take-off, the amount of power to be transmitted may be based on the power requirement of a power take-off connected to the at least one first electric machine 101a and / or the at least one second electric machine 101b.

[0082] In other words, the parameters related to the vehicle driving state may include vehicle-internal parameters such as a rotational speed(s) of the at least one first electric machine 101a and / or the at least one second electric machine 101b, a wheel slip of the first vehicle wheel 111a and / or the second vehicle wheel 111b, a weight of the vehicle 100, a rate or a rate of change of an acceleration request, an available power that can be transferred between the vehicle and the road, a vehicle driving mode, a vehicle steering angle, a load on the vehicle axles of the vehicle and / or a power request to a power take-off connected to the at least one first electric machine 101a and / or the at least one second electric machine 101b, as well as information related to the road section on which the vehicle is operated.such as a gradient of an approaching road section and the road condition of the upcoming road section. Such parameters can be determined in the vehicle 100 in various known ways, all of which fall within the scope of the invention. In-vehicle parameters can be available in the vehicle's control system. The information about the road section on which the vehicle is operating can be obtained based on map data, e.g., from digital maps available in the vehicle 100, which include, for example, topographical information, in combination with positioning information, e.g., GPS information. The positioning information can be used to determine the location of the vehicle 100 relative to the map data such that the road section information can be extracted from the map data.

[0083] Furthermore, such information may be acquired using one or more sensors 140 that may be included in the vehicle 100, such as one or more cameras or one or more radar devices. Furthermore, such information may be obtained from at least one other vehicle in front of the vehicle 100 and transmitted, for example, via the at least one device to the vehicle 100 using V2V communication.

[0084] In an optional step 206 in Fig. 2b, the at least one first electric machine 101a is disconnected from the first vehicle wheel 111a and / or the at least one second electric machine 101b is disconnected from the second vehicle wheel 111b, 112a, 112b before power is transmitted from the disconnected electric machine via the hydraulic connection in step 210.

[0085] In an optional step 208 in Fig. 2b the hydraulic pressure in the hydraulic connection is increased when the power is to be transferred between the electrical machines.

[0086] According to one embodiment of the invention, a control arrangement 120 for driving a vehicle 100 is presented. The vehicle comprises at least one first electric machine 101a configured to provide power to a first vehicle wheel 111a, and at least one second electric machine 101b configured to provide power to a second vehicle wheel 111b, 112a, 112b, wherein the at least one first electric machine 101a and the at least one second electric machine 101b are connected to one another by means of a hydraulic connection, wherein the control arrangement is configured to: The control arrangement 120 comprises devices 121 which are configured to transmit 210 a power between the at least one first electric machine 101a and the at least one second electric machine 101b by means of the hydraulic connection for at least one vehicle driving condition.

[0087] The control arrangement 120 according to the invention, e.g., a device or a control apparatus, can be configured to carry out all of the above, in the claims, and in the method steps of the exemplary embodiments described here. The control arrangement 120 is provided with the advantages described above for the respective exemplary embodiment.

[0088] The invention also relates to a vehicle 100 with the control arrangement 120.

[0089] In Fig. 5 shows the control arrangement 500 / 120, which may correspond to or comprise the above-described control unit 121 as well as further control units for carrying out the method steps according to the invention. The control arrangement 500 / 120 comprises a control unit 501, which can essentially be formed by any suitable type of processor or microcomputer, e.g., a circuit for digital signal processing (Digital Signal Processor, DSP), or a circuit with a predetermined specific function (Application Specific Integrated Circuit, ASIC). The computing unit 501 is connected to a memory unit 502 arranged in the control arrangement 500 / 120, which memory unit 502 provides the computing unit 501 with, e.g., the stored program code and / or the stored data that the computing unit 501 requires to be able to perform calculations.Likewise, the computing unit 501 is configured to store partial or final results of calculations in the storage unit 502.

[0090] Furthermore, the control arrangement 500 / 120 is provided with devices 511, 512, 513, 514 for receiving and transmitting input and output signals. These input and output signals may comprise waveforms, pulses, or other attributes that can be captured as information by the devices 511, 513 for receiving input signals and converted into signals that can be processed by the computing unit 501. These signals are then made available to the computing unit 501. The devices 512, 514 for transmitting output signals are configured to convert signals received from the computing unit 501 in order to generate output signals, for example by modulating the signals, which can be transmitted to other parts and / or systems in the vehicle 100.

[0091] Each of the connections to the devices for receiving and transmitting input and output signals can be established by one or more of: a cable, a data bus, such as a Controller Area Network CAN bus, a Media Oriented Systems Transport MOST bus, or another bus configuration, or a wireless connection. Those skilled in the art will appreciate that the computer described above can be formed by the computing unit 501 and the memory described above can be formed by the storage unit 502.

[0092] Control systems in modern vehicles typically include communication bus systems consisting of one or more communication buses to interconnect a number of electronic control units, ECUs or control devices, and various components located within the vehicle. Such a control system may include a large number of control units, and the responsibility for a particular function may be distributed among more than one control unit. Vehicles of the type shown therefore often include significantly more control units than in the Fig. 1 and Fig. 5, which is well known to the person skilled in the art.

[0093] In an embodiment shown, the invention can be implemented by one or more of the control units described above, such as control unit 121. However, the invention can also be implemented in whole or in part in one or more other control units already located in vehicle 100, or in a control unit according to the invention.

[0094] Here and in this document, units are frequently described as being configured to perform steps of the method according to the invention. This also includes the units being configured and / or set up to perform these method steps.

[0095] The control units used to implement the invention may be implemented as a single control unit, or logically separate but physically implemented in the same unit, or they may be arranged both logically and physically together. These units may, for example, correspond to groups of instructions, which may be in the form of programming code, that are input to and used by a processor / computing unit 501 when the units are active and / or used to perform their method steps.

[0096] It will be apparent to those skilled in the art that the embodiments described herein for supplying power to a vehicle 100 can also be implemented in a computer program that, when executed on a computer, instructs the computer to perform the method. The computer program is typically formed by a computer program product 503 stored on a non-transitory digital storage medium, with the computer program being integrated into the computer-readable medium of the computer program product. The computer-readable medium includes a suitable memory, such as: a read-only memory (ROM), programmable read-only memory (PROM), erasable PROM (EPROM), flash memory, electrically erasable PROM (EEPROM), a hard disk unit, etc.

[0097] The invention is not limited to the embodiments described above. Instead, the invention relates to and encompasses all various embodiments falling within the scope of the independent claims.

Claims

[1] A method (200) for driving a vehicle, the vehicle comprising at least one first electric machine (101a) configured to supply power to a first vehicle wheel (111a) and at least one second electric machine (101b) configured to supply power to a second vehicle wheel (111b, 112a, 112b), the at least one first electric machine (101a) and the at least one second electric machine (101b) being connected to each other by means of a hydraulic connection, the method comprising for at least one vehicle driving condition: Transmitting (210) a power between the at least one first electrical machine (101a) and the at least one second electrical machine (101b) by means of the hydraulic connection. [2] The method (200) of claim 1, wherein the vehicle travel condition occurs when the road grip of the first vehicle wheel (111a) differs from the road grip of the second vehicle wheel (111b, 112a, 112b), the method further comprising: Transferring power from the at least one first electric machine (101a) to the at least one second electric machine (101b) when the road grip of the second vehicle wheel exceeds the road grip of the first vehicle wheel, and vice versa. [3] Method (200) according to claim 1 or 2, wherein the first vehicle wheel (111a) and the second vehicle wheel (111b) are arranged on a common vehicle axle. [4] Method (200) according to claim 1 or 2, wherein the first vehicle wheel (111a) is a wheel of a first vehicle axle of the vehicle and the second vehicle wheel (112a, 112b) is a wheel of a second vehicle axle. [5] The method (200) of claim 4, wherein the first vehicle axle is mechanically separated from the second vehicle axle. [6] Method (200) according to one of the preceding claims, wherein the at least one first electrical machine (101a) is mechanically separated from the at least one second electrical machine (101b). [7] Method (200) according to one of the preceding claims, wherein the at least one first electric machine (101a) and / or the at least one second electric machine (101b) are / is configured to drive a power take-off (130) by means of a hydraulic connection, and wherein the vehicle driving condition comprises a power take-off power request, the method further comprising: Transferring the power from the at least one first electric machine (101a) or the at least one second electric machine (101b) to the hydraulically connected power take-off (130). [8] Method (200) according to one of the preceding claims, wherein the magnitude of the power transmitted by the at least one first electric machine (101a) and / or the at least one second electric machine (101b) via the hydraulic connection is based on one or more parameters related to the vehicle driving condition. [9] The method (200) of claim 8, wherein the vehicle driving condition related parameters include: - a rotational speed of the at least one first electrical machine (101a) and / or the at least one second electrical machine (101b), - wheel slip of the first vehicle wheel and / or the second vehicle wheel, - a weight of the vehicle (100), - a slope of an approaching road section, - a rate or rate of change of an acceleration requirement, - an available power that can be transferred between the vehicle and the road, - a vehicle driving mode, - a road condition for the upcoming road section, - a vehicle steering angle and / or - a load on the vehicle axles of the vehicle, and / or - a power request to a power take-off (130) connected to the at least one first electric machine (101a) and / or the at least one second electric machine (101b). [10] Method (200) according to one of the preceding claims, further comprising: Disconnecting (206) the at least one first electric machine (101a) from the first vehicle wheel (111a) and / or the at least one second electric machine (101b) from the second vehicle wheel (111b, 112a, 112b) before transmitting power from the disconnected electric machine via the hydraulic connection. [11] The method (200) of any preceding claim, wherein one or both of the at least one first and at least one second electric machine (101a, 101b) is or are configured to drive a hydraulic pump to supply hydraulic fluid to a hydraulic motor connected to the wheel driven by the other of the at least one first and at least one second electric machine (101a, 101b) to thereby transfer power from one of the at least one first and at least one second electric machine (101a, 101b) to the other. [12] The method (200) of claim 10, wherein the hydraulic pressure in the hydraulic connection is increased when the power is to be transferred between the electrical machines (101a, 101b). [13] A control arrangement (120) for driving a vehicle, the vehicle comprising at least one first electric machine (101a) configured to supply power to a first vehicle wheel and at least one second electric machine (101b) configured to supply power to a second vehicle wheel (111b, 112a, 112b), the at least one first electric machine (101a) and the at least one second electric machine (101b) being connected to one another by means of a hydraulic connection, the control arrangement being configured to, for at least one vehicle driving condition: to transmit (210) a power between the at least one first electrical machine (101a) and the at least one second electrical machine (101b) by means of the hydraulic connection. [14] A vehicle (100) comprising a control arrangement (120) according to claim 13. [15] A computer program comprising instructions which, when executed by a computer, cause the computer to carry out the method (200) according to any one of claims 1 to 12. [16] A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to perform the method (200) of any one of claims 1 to 12.

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