SE546093C2

SE546093C2 - Method and control arrangement for controlling a speed of a vehicle comprising a regenerative brake system

Info

Publication number: SE546093C2
Application number: SE2250276A
Authority: SE
Inventors: Manne Held; Mikael Alenius
Original assignee: Scania Cv Ab
Priority date: 2022-03-01
Filing date: 2022-03-01
Publication date: 2024-05-21
Also published as: DE102023102838A1; SE2250276A1

Abstract

A method (200) performed by a control arrangement for controlling a speed of a vehicle (100) comprising a regenerative brake system.The method (200) comprises, when travelling downhill, automatically applying a first brake force to control the speed of the vehicle to be maintained at a set speed level, Vmax, when this set speed level , Vmax, has been reached.Once the vehicle (100) approaches the end of a downhill road section (510) while the speed of the vehicle is controlled to be maintained at the set speed level, vmax, the applied brake force is adjusted (210) from the first brake force to a second brake force to accelerate the vehicle to an increased vehicle speed, vsch, exceeding the set speed level, vmax wherein the second brake force is applied by at least the regenerative brake system.Hereby, energy efficiency of the regenerative brake system is increased leading to increased vehicle efficiency and driving range.The invention relates also to a control arrangement (120), a vehicle (100) comprising the control arrangement (120), a computer program and a computer-readable medium.

Description

METHOD AND CONTROL ARRANGEMENT FOR CONTROLLING A SPEED OF A VEHICLE COMPRISING A REGENERATIVE BRAKE SYSTEM Technical field The invention relates to a method and a control arrangement for controlling a speed of a vehicle comprising a regenerative brake system.

The invention also relates to a computer program and a computer-readable medium and a vehicle comprising such a control arrangement.

Background The following background description constitutes a description of the background to the invention, which does not, however, necessarily have to constitute prior art.

One of the major global challenges today is reducing the negative impacts of road transportation on the environment due to greenhouse gas emissions. Moreover, the efficiency of a vehicle's energy consumption is one of the major factors influencing the cost, performance, and competitiveness of the vehicle. This has led to an increased interest in solutions aiming to improve energy efficiency in vehicles.

Today, vehicles, including heavy motor vehicles such as trucks and busses, are often equipped with speed control systems configured to maintain a set vehicle speed. When driving downhill, vehicles are affected by gravity in such a way that their speed increases. Therefore, speed control when driving downhill, often called downhill speed control, in general involves braking the vehicle. ln certain kind of vehicles, such as hybrid vehicles and electric vehicles comprising a regenerative brake system, some of the energy required for braking can be recovered. Thus, downhill speed control by means of regenerative braking contributes to increased energy efficiency of the vehicle.

Furthermore, a reduced energy consumption may be achieved by means of downhill speed control functions where the actual speed of the vehicle is allowed to deviate lO from a predetermined speed e.g. chosen by the driver. For example, the speed of the vehicle may be allowed to increase above an otherwise maintained speed limit when the vehicle reaches a final part of the downhill road section. This increase of the speed has the result that less braking power is needed, and that the vehicle will leave the downhill road section with an increased kinetic energy which can be used instead of energy stored in fuel or a battery e.g. in a following road section.

Summary lt is an objective of the present invention to provide a method and a control arrangement for mitigating or solving drawbacks of conventional solutions. ln particular an objective of the present invention is to provide a solution for controlling a speed of a vehicle comprising a regenerative brake system wherein an improved energy efficiency in the vehicle is obtained.

According to a first aspect of the invention, aforementioned and further objectives are achieved through a method performed by a control arrangement for controlling a speed of a vehicle, the vehicle comprising a regenerative brake system, the method comprising, when travelling downhill, automatically applying a first brake force to control the speed of the vehicle to be maintained at a set speed level vmax when this set speed level vmax is reached, the method further comprising, when the vehicle approaches the end of a downhill road section while the speed of the vehicle is controlled to be maintained at the set speed level vmax: adjusting the applied brake force from the first brake force to a second brake force to accelerate the vehicle to an increased vehicle speed vsch exceeding the set speed level vmax, wherein the second brake force is applied by at least the regenerative brake system.

The invention relates thus to a method for controlling a speed in an electrical vehicle, comprising a regenerative brake system. Examples of such vehicles are battery electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles. The regenerative brake system may comprise an electric machine functioning as an electric generator during braking of the vehicle such that some of the braking energy may be recovered.

The invention controls the speed of the vehicle by applying a brake force, here referred to as the second brake force, at least partly be the regenerative brake system while accelerating the vehicle to the increased vehicle speed vsch.

By applying the second brake force by at least the regenerative brake system, more of the brake energy may be recovered during the speed increase compared to if no brakes would have been applied.

Moreover, by utilising the invention, the speed increase may start at an earlier time instance than the speed increase according to previously known methods. This means that the average speed of the vehicle will increase leading to decreased trip time. Furthermore, the peak braking force will be reduced during the part of speed increase during which the set speed level vmax would have been maintained if the speed increase was performed according to previously known methods. By reducing the peak braking force electric losses in the vehicle are reduced. Hereby, energy efficiency of the regenerative brake system is increased leading to increased vehicle efficiency and driving range. Moreover, a temperature of the electric engine components and batteries may be reduced leading to lower risk of engine overheating and more efficient energy regeneration. ln an embodiment of the invention, the adjusting of the applied brake force comprises reducing the applied brake force from the first brake force to the second brake force.

The second brake force may thus here be a brake force smaller than the first brake force. Hereby, the invention may be applied in downhill road sections where a first brake force is required to maintain the speed of the vehicle at a set speed level vmax. This applies, for example, in situations when the downhill road section is long enough and/or steep enough to accelerate the vehicle from an initial speed at the beginning of the downhill road section to a speed exceeding the set speed level vmax before approaching the end of the downhill road section, if no brake force was applied.

Reducing the applied brake force in the downhill road section from the first brake force to the second brake force is done in such a way that the forces acting on the vehicle accelerate the vehicle, allowing the speed of the vehicle to increase. As previously explained, since the second brake force is applied at least partly by means of the regenerative brake system in the vehicle, some of the brake energy may be recovered. Hereby, the efficiency of regenerative brake system is increased when the vehicle is travelling on roads comprising long and/or steep downhill sections. ln an embodiment of the invention, the second brake force is applied solely by the regenerative brake system.

By applying the second brake force solely by the regenerative brake system, an increased amount of energy may be recovered by the regenerative brake system in the vehicle. Hereby, the energy efficiency of the vehicle is increased. ln an embodiment of the invention, the increased vehicle speed vsch exceeding the set speed level vmax is based on at least one of: a preset speed level, the set speed level vmax and/or a period of time that the vehicle will exceed the set speed level vmax.

By increasing the speed of the vehicle in the final part of the downhill road section may have the result that the vehicle will leave the downhill road section with an increased kinetic energy. The increased kinetic energy may be used instead of energy stored in fuel or a battery on a road section following the downhill which may lead to decreased energy consumption compared to if the set speed level vmax was maintained until the very end of the downhill slope. The amount of available kinetic energy in the end of the downhill road section will at least depend on the magnitude of the increased speed level. By utilizing the method of the invention, the magnitude of the increased speed level may be controlled in a number of different ways. For example, the magnitude of the increased speed level may be controlled to optimize energy efficiency, acceptability to the driver of the vehicle, acceptability to other road users and/or driver comfort. ln an embodiment of the invention, the method further comprises, when adjusting the applied brake force: determining the second brake force allowing the vehicle, when applied, to reach the increased vehicle speed vsch exceeding the set speed level vmax when the vehicle reaches the end of the downhill road section, wherein the adjusting of the applied brake force further comprises applying the determined second brake force such that the vehicle is accelerated to the increased vehicle speed vsch.

By determining the second brake force according to aspects of the invention, the speed of the vehicle may be controlled such that the increased vehicle speed vsch is reached and maximum available kinetic energy is gained in the end ofthe downhill section when the vehicle is no longer accelerated by the downhill road section. Hereby, the energy efficiency of the vehicle when driving downhill is optimised. ln an embodiment of the invention, the determining of the second brake force is at least partly based on one or more of: a road inclination data of the downhill road section, a curvature of the downhill road section, a weight of the vehicle, air resistance force acting on the vehicle, and/or a traffic situation within the downhill road section.

Hereby, the second braking power may be determined such that regeneration of energy during the speed increase is optimized and at the same time the speed of the vehicle is adapted to the vehicle characteristics and prevailing road conditions. ln an embodiment of the invention, the determining of the second brake force is further based on at least one of: a speed of the vehicle in the downhill road section, the first brake force applied in the downhill road section, and/or a heat development in the regenerative brake system _ Hereby, the same advantages as previously described are obtained. Moreover, the brake force to be applied during the speed increase may be adapted in such a way that risk of overheating of the regenerative brake system is decreased and/or to avoid jerky movements of the vehicle, i.e. rapid changes in acceleration when the vehicle's brakes are released. ln an embodiment of the invention the determined second brake force may change dynamically along the downhill road section.

Hereby, the second brake force to be applied during the speed increase may be regulated such that a required speed increase is obtained also when the inclination of the downhill road section changes. ln an embodiment of the invention, the method further comprises: determining a position in the downhill road section ahead of the vehicle where the applied brake force is to be adjusted to accelerate the vehicle to reach the increased vehicle speed vsch exceeding the set speed level vmax and adjusting the applied brake force when reaching said position.

By determining a position where the applied brake force is to be adjusted according to an aspect of the invention, the duration of the vehicle's speed increase, when a regenerative braking power will be applied, may be controlled. Hereby, the amount of energy regenerated during the speed increase may be optimized. ln an embodiment of the invention, the determining of the position is at least partly based on a road inclination data of the downhill road section.

Hereby, the amount of energy regenerated during the speed increase may be reliably controlled in all downhill sections. ln an embodiment of the invention, the determining of said position is based on the determined second brake force.

Hereby, the amount of energy regenerated during the speed increase may be reliably controlled and optimized. lO ln an embodiment of the invention, the method further comprises: applying a regenerative brake force prior to the vehicle reaching said set speed level vmax; and controlling a level of said regenerative brake force such that the vehicle reaches said set speed level vmax prior to or at the position where the applied brake force is adjusted from the first brake force to the second brake force to further accelerate the vehicle.

Hereby, the amount of regenerated energy may be further increased in the downhill road section. ln an embodiment of the invention, the method comprises: prior to adjusting the applied brake force to accelerate the vehicle to an increased vehicle speed vsch exceeding the set speed level vmax the vehicle speed is maintained at set speed level vmax at least partly by means of the regenerative brake system.

Hereby, the amount of regenerated energy may be further increased in the downhill road section.

According to a second aspect, the invention relates to a control arrangement for controlling a speed of a vehicle, the vehicle comprising a regenerative brake system, the control arrangement being configured to, when the vehicle is travelling downhill, automatically apply a first brake force to control the speed of the vehicle to be maintained at a set speed level vmax when this set speed level vmax is reached, the control arrangement being further configured to, when the vehicle approaches the end of a downhill road section while the speed of the vehicle is controlled to be maintained at the set speed level vmax, adjust the applied brake force from the first brake force to a second brake force to accelerate the vehicle to an increased vehicle speed vsch exceeding the set speed level vmax wherein the second brake force is applied by at least the regenerative brake system. lO lt will be appreciated that all the embodiments described for the method aspects of the invention are applicable also to at least one of the control arrangement aspects of the invention. Thus, all the embodiments described for the method aspects of the invention may be performed by the control arrangement, which may also be a control device, i.e. a device. The control arrangement and its embodiments have advantages corresponding to the advantages mentioned above for the methods and their embodiments.

According to a third aspect of the invention, aforementioned and further objectives are achieved through a vehicle comprising the control arrangement of the second aspect. The vehicle may for example be a bus, a truck, or a car.

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

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.

The above-mentioned features and embodiments of the method, the control arrangement, the vehicle, the computer program, and the computer-readable medium, respectively, may be combined in various possible ways providing further advantageous embodiments.

Further advantageous embodiments of the method, the control arrangement, the vehicle, the computer program, and the computer-readable medium according to the present invention and further advantages with the embodiments of the present invention emerge from the detailed description of embodiments.

Brief description of the drawinqs Embodiments of the invention will be illustrated in more detail below, along with the enclosed drawings, where similar references are used for similar parts, and where: lO Figure1 shows a schematic view illustrating an exemplary vehicle in which embodiments of the present invention may be implemented; Figure 2 shows a flow chart of a method for operating an electrical motor system of a vehicle according to embodiments of the invention; Figure 3 illustrates the principle of one embodiment of the invention in one driving süuaﬁon; Figure 4 illustrates the principle of one further embodiment of the invention in one driving situation; Figure 5 shows a control arrangement, in which a method according to any one of the herein described embodiments may be implemented.

Detailed description As previously explained, many heavy vehicles are today equipped with a downhill speed control system controlling the speed of the vehicle when driving downhill. A traditional downhill speed control brakes the vehicle when a braking speed level vdhsc is reached. A braking speed level vdhsc for the downhill speed control may correspond to a set speed of a cruise control system in the vehicle, but most often corresponds to the cruise control set speed plus an offset speed.

Some previously known downhill speed control systems allow a speed increase above the braking speed level vdhsc at the end of the downhill road section. The brakes may be released before the vehicle reaches the end of the downhill road section and the speed of the vehicle is increased to a level vsch which is greater than the braking speed level vdhsc at the end of the downhill. Thus, during the final part of the downhill road section, the vehicle gains kinetic energy, which can be used instead of energy stored in fuel or a battery when the downhill road section has ended. By avoiding braking in the last part of the downhill, both time and energy is lO lO saved which may lead to increased competitive advantage of such downhill speed control systems.

However, it has been realized that the current combination of braking at a constant speed, when driving downhill followed by releasing the brakes fully in the final part of the downhill, may not be fully energy optimal for vehicles with the ability to regenerate energy during braking. lt is thus an objective of the present invention to provide a method and a control arrangement for controlling a speed of a vehicle comprising a regenerative brake system such that these problems are at least partly solved.

Figure 1, which will be used to explain the herein presented embodiments, schematically illustrates a vehicle 100 and its power train. The vehicle 100 may e.g., be a car, a bus, or a truck. The power train of the vehicle 100 illustrated in Figure 1 comprises an electrical motor system with at least one electrical machine 101 configured for driving the drive wheels 111, 112 of the vehicle 100. ln the shown embodiment, the vehicle 100 comprises two driving wheels 111, 112 but it should be understood that the vehicle 100 may be arranged with one of more driving wheels. The at least one electrical machine 101 may, as depicted in Figure 1, be connected to a gearbox 102 via an input shaft 104. The vehicle 100 may comprise a propeller shaft 105 from the gearbox 102 which drives the driving wheels 111, 112 via a central gear 103, for example a conventional differential, and two drive shafts 106, 107 of the vehicle 100. lt should be understood that the vehicle 100 may be arranged in any known way, for example without a gearbox 102 or conventional differential without limiting the scope of the invention.

The at least one electrical machine 101 may be arranged essentially anywhere, as long as torque is provided to one or more of the wheels 111, 112, for example adjacent to one or more of the wheels, or in any other conventional way as is understood by a skilled person. The at least one electrical machine 101 may be provided with electrical power from a battery system (not depicted) included in the electrical motor system of the vehicle lO ll The vehicle 100 may, as illustrated in Figure 1, be a pure electrical vehicle only including the one or more electrical machines 101 for driving the drive wheels 111, 112. However, the vehicle 100 may also be a so-called hybrid vehicle and also include an internal combustion engine (not depicted) which may, in a conventional manner, be connected to the gearbox 102, e.g., via a clutch (not depicted).

The electrical motor system including the electrical machine 101 as well as various components of the vehicle's drive line may be controlled by a vehicle control system via a control arrangement 120. The control arrangement 120 may be distributed on several control units configured to control different parts of the vehicle 100. The control arrangement 120 may e.g. include an adjusting unit 121 arranged for performing the method steps of the disclosed invention as is explained further on. The control arrangement 120 and/or another control arrangement may further be configured for controlling any other units/devices/entities of the vehicle 100. However, in Figure 1, only the units/devices/entities of the vehicle useful for understanding the present invention are illustrated. The control arrangement 120 will be described in further detail in Figure The vehicie 100 may further comprise various different hrake systems (not depicted), e.g. a convehtiohai service braite system, vt/hich may, for exampie, comprise braite discs vvith associated orake iinihgs situated adjaceht to each wheei. Heavy vehicies are often provided with further braite systems, e.g. in the form of conventionai retarders 112 and/or other suppiementary brake systems such as various kinds of exhaust brake systems, compression hrake systems, eiectromagnetio brake systems, engine braites, and regenerative braite systems.

Clin the basis of commands initiated by the vehicies driver and/or other cohtroi units, the controi arrangement (or some other suitahie controi unit) sencis controi sighais to suitabie system moduies to demand desired oraitihg force from desired oraite systems. Suppiementary hrake systems may aiso he controiied directiy hy the driver, e.g. via outtons or pedais, in which case the pedai or iever may be direotiy connected to another cohtroi unit Which sehds information to, for examoie, a retarder controi unit. lOThe vehicle 100 may further include one or more sensors 130, e.g. at least one radar located at suitable positions within the vehicle Further, the vehicle 100 may comprise a positioning system/unit 140. The positioning unit 140 may be based on a satellite navigation system such as the Navigation Signal Timing and Ranging (Navstar), Global Positioning System (GPS), Differential GPS (DGPS), Galeo, GLONASS, or the like. Thus, the positioning unit 140 may comprise a GPS receiver.

The vehicle 100 may further include at least one communication device 150 arranged for communication with at least one entity 160 external to the vehicle 100, such as at least one communication entity of another vehicle. Correspondingly, the at least one communication device 150 may be a vehicle-to-vehicle, V2V, communication device, a vehicle-to-infrastructure, V2l, communication device, a vehicle-to-everything, V2X, communication device, and/or a wireless communication device such that communication between the vehicle and the at least one external entity 160 is achieved/provided.

The proposed invention will now be described with reference to a method 200, disclosed in Figure 2, for controlling a speed of a vehicle, such as the vehicle 100 disclosed in Figure 1 comprising a regenerative brake system. The method 200 is performed by a control arrangement, such as the control arrangement 120 disclosed in Figure 1. The method 200 comprises, when the vehicle 100 is travelling downhill, automatically applying a first brake force to control the speed of the vehicle to be maintained at a set speed level vmax when this set speed level vmax is reached.

The method further comprises when the vehicle 100 approaches the end of a downhill road section while the speed of the vehicle is controlled to be maintained at the set speed level vmax: ln step 210 in Figure 2, adjusting the applied brake force from the first brake force to a second brake force to accelerate the vehicle 100 to an increased vehicle speed lOvsch exceeding the set speed level vmax wherein the second brake force is applied by at least the regenerative brake system.

The present invention may be employed on substantially all types of vehicles which have a regenerative brake system i.e., electrical vehicles that uses one or more electrical machines for propulsion. Examples of such vehicles are battery electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles. lt is to be understood that the vehicle 100, while in motion, is subjected to various forces, according to basic principles of physics, especially the Newtons second law of motien, some forces accelerating the vehicle in the direction of motion and other forces opposing the current movement of the vehicle. Such forces may arise, e.g., due to road inclination, the air resistance acting of the vehicle, internal friction losses in the vehicle's power train as well as losses caused by friction between the wheels of the vehicle and the road surface. ln order to increase the vehicle speed, a force exceeding the net force acting on the vehicle against the vehicle direction of motion needs to be delivered e.g., by providing a tractive force to accelerate the vehicle. Conversely a brake force may be applied to increase the forces acting against the current direction of motion, e.g., to achieve a lower speed. The brake forces referred to in this specification, i.e., the first and the second brake force correspond to the brake force applied by the regenerative brake system or/and one or more additional brake systems in the vehicle.

As previously explained, the set speed level vmax may be a defined maximum speed level that the vehicle should not exceed when driving on a downhill road section. This maximum speed vmax may be used to prevent the vehicle reaching a too high speed, e.g., a speed exceeding the speed limit for the section of the road or exceeding a maximum permissible speed for the vehicle. On a given section of road the set speed level vmax may thus be a speed limit which the driver does not wish to exceed, e.g., to avoid the risk of speeding. The speed level vmax may be set in a number of different ways which will be explained further on. ln the present invention, when the set speed level vmax has been reached, it is maintained automatically. lOThe present invention controls the speed increase of the vehicle 100 approaching an end of a downhill road section in such a way that energy regeneration is enabled. lnstead of releasing the applied brakes when approaching the end of the downhill road section to increase the speed to an increased vehicle speed vsch according to previously known methods, the invention applies, during the speed increase, a brake force, herein denominated as the second brake force, by means of at least the regenerative brake system. This results in some of the brake energy being recovered by the regenerative brake system. By utilising the invention, the speed increase may start at an earlier time instance than the speed increase according to previously known methods. This means that the speed increase and regenerative braking may take place over a longer period of time. Hereby, the peak braking force is reduced during the speed increase and thus the electric losses will be reduced. Hereby, more energy may be recovered by the regenerative brake system in the vehicle. ln addition, by reducing the peak braking force during the speed increase, the temperature of the electric engine components and batteries will be reduced leading to lower risk of engine overheating and more efficient energy regeneration. ln addition to the method step 210, the method 200 may in an embodiment, comprise additional optional steps. Thus, in embodiments, the method step 210 may be preceded by one or more optional steps 202 - 208 which are depicted in Figure 2 in dashed boxes. The optional method steps 202 - 208 will be described further on.

The method 200 and further embodiments of the invention will now be explained in more detail with reference to Figure 3. Figure 3 illustrates a non-limiting example of a driving scenario, in which the method 200 and further embodiments of the invention may be implemented. Figure 3 shows a vehicle, such as the vehicle 100 disclosed in Figure 1, driving with an actual speed vad that may vary along a route, where topography for the section of road on which the vehicle 100 is driving is shown at the top of the figure.

As previously explained, the vehicle 100 may comprise a regenerative brake system. The regenerative brake system may be ah integrai part ef the vehiciee 100 power train, where the electricei machine 101 ie run in generator mode during braking se that et lO least some of the braking energy is recevered. The regenerative brake system may, according to conventional solutions, comprise componehts for recovering or transferring the energy which is braked away be the brake system.

The invention is here described in terms of vehicle's positions, such as P0, P1, P2, P3, P4, P5 and P6, but a person ski||ed in the art will appreciate that these positions correspond to respective points in time. Here the section of the road comprises a downhill gradient, 510, between a position P1 and P As previously explained, according to the invention, the speed of the vehicle is controlled automatically in the downhill road section 510 to maintain a set speed level vmax when this set speed level vmax has been reached. ln one example, the speed of the vehicle may be controlled in the vehicle's power train control system executing the logic of method 200 and altering the manual driver control of the accelerator and/or brake pedal. ln another example, the vehicle 100 may be equipped with cruise control. One object of cruise control is to achieve a predetermined speed. Control of vehicle speed is often conducted in vehicles by two interacting systems, i.e., a cruise control system which demands torque from an engine system to maintain a cruise control set speed vcasei, and a downhill speed control system which prevents the vehicle from developing excessive speed, particularly on downhill road sections by maintaining a braking speed level vdhsc.

Thus, in one example, the speed of the vehicle 100, in the downhill road section 510 may be controlled by means of a downhill speed control system and the set speed level vmax may thus correspond to a speed level vdhsc that has been set in the downhill speed control system.

The set speed level vmax may be set in a number ofdifferent ways. lt may, for example, be set by the driver or by other authorized personnel through some type of input, for example by pressing a button, activating a brake pedal, or through some other conventional type of input. ln another example, the set speed level vmax may be set, manually by the driver or automatically, as an offset to a set speed for a cruise control system in the vehicle. lOWhen the vehicle 100 is driving in the downhill road section 510, the speed of the vehicle is controlled automatically by controlling one or more brake systems in the vehicle 100 such that the set speed level vmax is not exceeded. The one or more brake systems may, as previously explained, comprise the regenerative brake system. Optionally the one of more brake systems may furthermore comprise at least ene additional brake system. The at least sne aclditionai brake system may, as previously explained with reference te Figure 1, be a conventional service brake system, a retarder and/er other suppiementary brake systems such as one er mere sf various kinds ef exhaust brake systems, compression brake systems, eiectremagiwetic brake systeins, engine brakes etc.

Figure 3 also shows the actual speed vaa of the vehicle 100, depicted as the solid thick line in the lower part of the figure, as well as a brake force applied by the vehicle's brake system to control the speed of the vehicle 100. The brake force is depicted as the solid line in the middle part of the figure.

As illustrated in Figure 3, the speed of the vehicle driving between the positions P0 and P6 may vary between a first speed level v1, a set speed level vmax, and an increased speed level vsch. The first speed level v1 may, for example, correspond to a speed level which the vehicle will automatically maintain on the road section between the positions P0 and P1 _ The first speed level vi may for example correspond to a set speed for the cruise control system vcesei, when the speed of the vehicle is controlled by a cruise control system. The set speed level vmax may correspond to a speed level at which the vehicle will be braked to maintain the speed when driving downhill. The set speed may for example correspond to a braking speed vdhsc maintained by a downhill speed control system, when the speed of the vehicle is controlled by a downhill speed control system. The increased speed level vsch may be a speed level exceeding the set speed level vmax, that the vehicle is allowed to accelerate to at the end of the downhill road section to gain kinetic energy, which can be used instead of energy stored in fuel or a battery. lOThe magnitude of the increased speed level vsch, or rather the difference between the set speed level vmax, and the increased speed level vsch, is a factor deciding the amount of kinetic energy that may be gained by the vehicle at the end of the downhi|| road section. ln an embodiment, the increased vehicle speed vsch may be based on various parameters, such as a preset speed level, the set speed level vmax, and a period of time that the vehicle will exceed the set speed level vmax. ln one example, the increased vehicle speed vsch may thus be based on a preset speed level corresponding to a speed level that the vehicle should not exceed, or to a speed limit that should not be exceeded on the road section where the vehicle is travelling. ln one example, the preset speed level may be a speed level corresponding to the increased vehicle speed vsch, selected, according to conventional methods, by the driver of the vehicle. ln one example, the increased vehicle speed vsch may be based on the set speed level vmax, and may correspond to the set speed level vmax, plus an offset value. ln one example, the increased vehicle speed vsch may be based on a period of time that the vehicle will exceed the set speed level vmax. ln a non-limiting example, the vehicle may be travelling on a road where the legal speed limit is 90km/h. The increased vehicle speed vsch may be set to 90km/h plus an offset, where the offset may depend on a time limit during which the vehicle speed may exceed the speed limit. ln another example, the increased vehicle speed vsch may be based on the set speed level vmax maintained in the downhi|| road section. The increased vehicle speed vsch may for example correspond to the set speed level vmax plus an offset speed. An offset speed may be det manually by e.g. the driver, determined automatically or correspond to a preset value.

As can be seen in Figure 3, the actual speed vad of the vehicle 100 may be maintained at the first speed level v1 when the vehicle is driving on the road section between the positions P0 and P1. At the position P1, the vehicle enters the downhi|| road section 510 where, due to gravity, the actual speed vad of the vehicle 100 starts to increase. At the position P2, the actual speed of the vehicle has reached the set speed level vmax and a first brake force Fi is applied to maintain the set speed level vmax in the downhi|| lOroad section. The first brake force F1 may be automatically applied by controlling one or more brake systems in the vehicle 100. ln one example, the set speed level vmax may be maintained, for example, by applying the first brake force F1 solely by means of the regenerative brake system. ln another example, in one embodiment, the vehicle speed may be maintained at set speed level vmax at least partly by means of at least one additional brake system in the vehicle, for example solely by means of at least one additional brake system, or by means of the regenerative brake system and at least one additional brake system.

As previously explained, in previously known solutions, in order to achieve energy efficient driving by taking advantage of the kinetic energy the vehicle acquires on downhill road sections, the set speed level vmax would be automatically maintained until the end of the downhill was approached. Before reaching the end of the downhill, i.e. at the position P4 in Figure 3, the one or more brake systems in the vehicle 100 would have been released (brake force Fo in the figure representing no applied brakes) allowing the vehicle speed to increase and at the end of the downhill road section, at the position P5 in Figure 3, reach the vehicle speed vsch exceeding the set speed level vmax. Note that between the position P3 and the position P5 in Figure 3, the actual speed of the vehicle 100 and the brake force applied according to herein described previously known solutions is illustrated by dotted lines.

According to the invention, the vehicle is instead accelerated from the set speed level vmax to the increased vehicle speed vsch by adjusting the applied brake force from the first brake force F1 to a second brake force Fz. Moreover, the second brake force Fz is, according to the invention, applied at least partly by the regenerative brake system in the vehicle. Thus, as may be seen in Figure 3, the invention applies a brake action, corresponding to the second brake force F2, from the brake activation position P3 until the position P5 when the increased vehicle speed vsch has been reached. Thus, according to the invention, the speed of the vehicle will start to increase at a position earlier than in previously known solutions, leading to the braking taking place over a longer period of time during which some of the braking energy may be regenerated. Consequently, compared with previously known methods, the vehicles energy efficiency will be further improved. lOAs previously explained, when the vehicle 100 enters the downhill road section 510, i.e., at the position P1 in Figure 3, its actual speed vad will, due to gravity, start to increase. The vehicle's acceleration depends on parameters like the inclination of the downhill road section as well as the weight of the vehicle. ln the non-limiting example illustrated in Figure 3, the vehicle 100 reaches the set speed level vmax at the position P2, i.e., earlier than the brake activation position P3. Thus, between the positions P2 and P3 the applied brake action, corresponding to the first brake force F1, brakes the vehicle to maintain the set speed level vmax. ln order to allow the vehicle to accelerate at the brake activation position P3 the applied brake force needs to be reduced from the first brake force F1 to the second brake force Fz. Thus, in one embodiment, adjusting the applied brake force may comprise reducing the applied brake force from the first brake force F1 to the second brake force Fz.

According to the invention, the second brake force F2 is applied at least partly by the regenerative brake system in the vehicle in such a way that the vehicle is accelerated when the second brake force Fz has been applied. Thus, in one example, the second braking force P2 may be applied by the regenerative brake system and by at least one additional brake system in the vehicle. ln another example, in an embodiment, the second brake force Fz may be applied solely by the regenerative brake system.

The amount of brake force to be applied by the regenerative brake system may be determined in a number of different ways. ln one example, the amount of brake force to be applied by the regenerative brake system may be based on the brake force applied during the speed increase of the vehicle to the increased vehicle speed vsch, i.e., on the second brake force Fz. lt may, for example, be favourable to combine the braking force applied by the regenerative brake system with a braking force applied by at least one additional brake system in the vehicle e.g., to optimize energy regeneration in the vehicle. ln another example, the second braking force Fz may exceed the total braking capacity that may be provided by the regenerative brake system. Thus, additional brake force may need to be provided by at least one additional brake system in the vehicle. lO ln the road section following the downhill road section 510, between the position P5 and the position P6 in Figure 3, the vehicle 100 is no longer accelerated by the downhill gravity forces and starts to lose speed. Here, the speed of the vehicle may again be automatically controlled to maintain the first speed level v1 resulting in the actual speed vad of the vehicle 100 dropping to the first speed level v As previously explained, the method 200 may in an embodiment, comprise additional optional steps. Thus, in embodiments, the method step 210 may be preceded by one or more optional steps 202 - 208 as shown in Figure 2. lt should be noted that the method steps illustrated in Figure 2 and described herein do not necessarily have to be executed in the order illustrated in Figure 2. The steps may essentially be executed in any suitable order, as long as the physical requirements and the information needed to execute each method step is available when the step is executed. ln an embodiment, in an optional step 202 in Figure 2, preceding the previously described step 210, when adjusting the applied brake force, the second brake force may be determined. The second brake force may be determined in such a way that when it is applied, the speed of the vehicle is allowed to reach the increased vehicle speed vsch exceeding the set speed level vmax at the end of the downhill road section. Such scenario is illustrated in Figure 3 where the increased vehicle speed vsch is reached at the end of the downhill road section i.e., at the position P When the optional step 202 has been performed and the second brake force Fz has been determined, adjusting of the applied brake force in step 210 may be performed by applying the second brake force F2 determined in step 202 in such a way that the vehicle is accelerated to the increased vehicle speed vsch. Thus, the second brake force may be determined prior to the applied brake force is adjusted.

The second brake force may be determined in a number of various ways. The second brake force may, for example, be determined at least based on the level of the increased vehicle speed vsch that the vehicle shall reach, and on the position when the increased vehicle speed vsch is to be reached. ln one example, the second brake force lOmay be determined in such a way that, when applied at a suitable position, the increased vehicle speed vschwill be reached in the end of the downhill road section, in order to maximize the energy saving in the vehicle. ln an embodiment, the second brake force may be determined at least partly based on one or more of a road inclination data of the downhill road section 510, a curvature of the downhill road section 510, a weight of the vehicle 100, and/or air resistance force acting on the vehicle 100. For example, by using Newton's laws of motion the required brake force needed to accelerate the vehicle to the increased vehicle speed vsch in the downhill road section 510 may be calculated considering the tractive and braking forces acting on the vehicle due to road inclination, the air resistance, road curvature as well as vehicle characteristics such as vehicle dimensions, a weight of the vehicle to mention a few.

Information related to the characteristics of the section of road in front of the vehicle, such as data related to road inclination and road curvature, may easily be determined based e.g. on map information, on GPS information, on radar information, on camera information, on information from another vehicle, on positioning-related and road gradient information stored previously in the vehicle 100, and/or on information obtained from traffic systems related to said road section. Air resistance acting on the vehicle may be determined according to conventional methods based on vehicle's internal parameters, like weight, the speed of the vehicle and the tractive force provided by the vehicle's electrical machine or engine. The vehicle internal parameters like weight of the vehicle 100 may be obtained from the vehicle's control system via one or more communication buses linking the control arrangement 120 with various components and controllers located on the vehicle ln an embodiment, the second brake force may also be determined based on the traffic situation within the downhill road section 510 in such a way that there will be no risk of running into, or coming too close to, other vehicles in front of the vehicle Generally, information related to current traffic situation on a road section may be obtained in the vehicle from one or more sensors 130, e.g. one or more camera, one or more radar equipment, etc. Moreover, such information may be obtained based on lOinformation provided by at least one second vehicle, e.g. by V2V communication, and/or by an infrastructure entity, e.g. by V2| communication, or based on information obtained from traffic systems related to the road section. ln one example, the second brake force may be determined in such a way that the level of the second brake force is favourable for regeneration with the regenerative brake system. For example, a certain brake system may have a maximum regeneration capacity corresponding to a certain brake force limit value, in which case the second brake force may be determined to be below this limit value, where the point in time in which the second brake force is applied may depend on this determination. Thus, the second brake force may be determined in such a way that the brake energy utilised by the regenerative brake system is optimised. ln addition, the second brake force may be based on further parameters that are to be optimized e.g., energy efficiency, acceptability to the driver of the vehicle, acceptability to other road users and/or driver comfort. ln an embodiment, the second brake force may, e.g., be determined based on a speed of the vehicle in the downhill road section 510, and/or the first brake force applied in the downhill road section. ln non-limiting examples, the second brake force may be determined to achieve one of the following during a speed increase to the increased vehicle speed vsch: a constant acceleration, a constant braking force or a constant power applied by the vehicles regenerative brake system. Moreover, the second brake force may be determined to avoid jerky movements of the vehicle, i.e., rapid changes in acceleration when the vehicle's brakes are released. ln an embodiment, the second brake force may furthermore be determined based on a heat development in the regenerative brake system. For example, the second brake force may be selected such that the temperature of the regenerative brake system, or any of its components, may not exceed a temperature threshold value. Information related to heat development in the regenerative brake system may be obtained by e.g., temperature monitoring of the regenerative brake system by means of suitable SGFISOFS. lOln an embodiment, the determined second brake force may change dynamically along the downhill road section 510. For example, when it is desirable to achieve a constant acceleration, the second brake force may be selected based on an adaptive algorithm analysing how much brake force is required and adjust the second brake force dynamically based on the vehicle's speed and to road inclination. ln an embodiment, in an optional step 204 in Figure 2, preceding the previously described step 210, a brake activation position is determined to a position where the applied brake force is to be adjusted to accelerate the vehicle 100 to reach the increased vehicle speed vsch exceeding the set speed level vmax. The position may be in the downhill road section 510 ahead of the vehicle 100. An example of such brake activation position P3 is depicted in Figure 3, in which the vehicle 100 is on the downhill road section 510 and is accelerated by its weight and at the same time the second brake force is applied such that the vehicle is accelerated. ln one example, the brake activation position may be determined to a position prior to the position where the vehicle's speed would increase if no brake force was applied during the speed increase, e.g., position P4 in Figure ln an embodiment, the brake activation position may be determined at least partly based on a road inclination data of the downhill road section 510. For example, the brake activation position may be determined to a position from which it is calculated that the increased vehicle speed vsch may be reached at the end of the downhill road section 510 by applying a brake force which may be provided by the regenerative brake system. ln an embodiment, the brake activation position may be determined based on the second brake force determined in the optional step 202 in Figure 2. Thus, the brake activation position may be determined as the position at which the determined second brake power needs to be applied to accelerate the vehicle to the increased vehicle speed vsch in the end of the downhill road section. lOWhen the optional step 204 has been performed and the brake activation position has been determined, adjusting of the applied brake force in step 210 may be performed when said position has been reached. ln an embodiment, in an optional step 206 in Figure 2, preceding the previously described step 210, a regenerative brake force may be applied prior to the vehicle reaching said set speed level vmax.

When the optional step 206 has been performed, the method continues to the optional step ln the optional step 208 in Figure 2, the level of the regenerative brake force may be controlled such that the vehicle reaches said set speed level vmax prior to or at the position where the applied brake force is adjusted from the first brake force to the second brake force to further accelerate the vehicle. ln the embodiment according to the optional steps 206 and 208, the vehicle may be controlled to accelerate immediately after the set speed level vmax has been reached when approaching the end of the downhill road section. The regenerative brake force applied prior to the vehicle reaching said set speed level vmax may be so low, that the speed of the vehicle increases in the downhill road section 510. Thus, in one example, adjusting the applied brake force from the first brake force to a second brake force to accelerate the vehicle in step 210, in Figure 2 may correspond to applying a second brake force corresponding to the first brake force applied prior to the vehicle reaching said the speed level vmax.

A driving scenario in which the above-mentioned embodiment may be implemented is illustrated in Figure 4. The driving scenario in Figure 4 is illustrated in a similar fashion as the driving scenario shown in Figure 3. Thus, Figure 4 shows a vehicle 100 driving with an actual speed vad that may vary along a route, through a road section with a topography as illustrated at the top of the Figure 4. As may be seen the road section comprises a downhill part between the position P1 and the position P4 in Figure lO Figure 4 also shows the actual speed vad of the vehicle 100 when driving on said road section, depicted as the solid thick line in the lower part of the figure, as well as a brake force applied by the vehicle's brake system to control the speed of the vehicle The brake force is depicted as the solid line in the middle part of the figure. ln similarfashion as described with reference to Figure 3, the speed of the vehicle may be controlled automatically in the downhill road section 510 to maintain a set speed level vmax when this set speed level vmax has been reached.

As can be seen in Figure 4, the actual speed vad of the vehicle 100 may be maintained at a first speed level v1 when the vehicle is driving on the road section between the position P0 and the position P1 _ At the position P1 , the vehicle enters the downhill road section 510 where, due to gravity, the actual speed vad of the vehicle 100 starts to increase. The speed of the vehicle 100 may here be controlled in the downhill road section by applying a regenerative brake force F2 prior to the vehicle reaching said set speed level vmax at the position P As previously explained with reference to Figure 3, in previously known solutions in order to achieve energy efficient driving by taking advantage of the kinetic energy the vehicle acquires on downhill road sections, the set speed level vmax would be automatically maintained until the end of the downhill was approached. Maintaining the set speed level vmax at the position P2 where the set speed level vmax was reached would have required that a braking power corresponding to the first braking power was applied at the position P2 and maintained until the position P3. At the position P3, when approaching the end of downhill, the one or more brake systems in the vehicle 100 would, according to prior art solutions, have been released (brake force Fo in the figure representing no applied brakes) allowing the vehicle speed to increase and at the end of the downhill road section, and, at the position P4, reach the vehicle speed vadi exceeding the set speed level vmax. Note that between the position P2 and the position P4 in Figure 4, the vehicle speed and the brake force applied according to herein described previously known solutions is illustrated by a dotted line. lOAccording to present invention, the vehicle is instead accelerated from the set speed level vmax to the increased vehicle speed vsch at the position P2 by maintaining the applied brake force F2. Thus, in the non-limiting example illustrated in Figure 4, the applied brake force is adjusted from the first brake force F1 to a second brake force Fz by maintaining the brake force applied prior to increasing the speed of the vehicle from the set speed level vmax.

As described with reference to Figure 3, in the road section between the position P4 and the position P5, the vehicle 100 is no longer accelerated by the downhill gravity forces and starts to lose speed. Here, the speed of the vehicle may again be automatically controlled to maintain the first speed level v1 resulting in the actual speed vad of the vehicle 100 dropping to the first speed level v1. For example, the speed of the vehicle may be reduced through the external forces acting on the vehicle.

According to an aspect of the invention, a control arrangement 120 for controlling a speed of a vehicle 100 is presented. The control arrangement 120 includes means 121 arranged for adjusting an applied brake force from the first brake force to a second brake force to accelerate the vehicle 100 to an increased vehicle speed vsch exceeding the set speed level vmax wherein the second brake force is applied by at least the regenerative brake system.

The control arrangement 120, e.g. a device or a control device according to the invention may be arranged for performing all of the above, in the claims, and in the herein described embodiments method steps. The control arrangement 120 is hereby provided with the above-described advantages for each respective embodiment.

The invention is also related to a vehicle 100 including the control arrangement Now turning to Figure 5 which illustrates the control arrangement 600/120, which may correspond to or may include the above-mentioned control unit 121 i.e. the control unit performing the method steps of the disclosed invention. The control arrangement 600/120 comprises a computing unit 601, which can be constituted by essentially any suitable type of processor or microcomputer, e.g. a circuit for digital signal processing (Digital Signal Processor, DSP), or a circuit having a predetermined specific function lO(Application Specific Integrated Circuit, ASIC). The computing unit 601 is connected to a memory unit 602 arranged in the control arrangement 600/120, which memory unit provides the computing unit 601 with, e.g., the stored program code and/or the stored data which the computing unit 601 requires to be able to perform computations. The computing unit 601 is also arranged to store partial or final results of computations in the memory unit ln addition, the control arrangement 600/120 is provided with devices 611, 612, 613, 614 for receiving and transmitting input and output signals. These input and output signals can contain waveforms, impulses, or other attributes which, by the devices 611, 613 for the reception of input signals, can be detected as information and can be converted into signals which can be processed by the computing unit 601. These signals are then made available to the computing unit 601. The devices 612, 614 for the transmission of output signals are arranged to convert signals received from the computing unit 601 in order to create output signals by, e.g., modulating the signals, which can be transmitted to other parts of and/or systems in the vehicle Each of the connections to the devices for receiving and transmitting input and output signals can be constituted by one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media Orientated Systems Transport bus), or some other bus configuration; or by a wireless connection. A person skilled in the art will appreciate that the above-stated computer can be constituted by the computing unit 601 and that the above- stated memory can be constituted by the memory unit Control systems in modern vehicles commonly comprise communication bus systems consisting of one or more communication buses for linking a number of electronic control units (ECU's), or controllers, and various components located on the vehicle. Such a control system can comprise a large number of control units and the responsibility for a specific function can be divided amongst more than one control unit. Vehicles of the shown type thus often comprise significantly more control units than are shown in Figures 1 and 5, which is well known to the person skilled in the art within this technical field. lOln a shown embodiment, the invention may be implemented by the above-mentioned control unit 121. The invention can also, however, be implemented wholly or partially in one or more other control units already in the vehicle 100, or in some control unit dedicated to the invention.

Here and in this document, units are often described as being arranged for performing steps of the method according to the invention. This also includes that the units are designed to and/or configured to perform these method steps.

The control unit 121 is in Figure 1 illustrated as a separate unit. This units may, however, be logically separated but physically implemented in the same unit or can be both logically and physically arranged together. The unit may e.g. correspond to groups of instructions, which can be in the form of programming code, that are input into, and are utilized by a processor/computing unit 601 when the unit is active and/or is utilized for performing its method step.

The person skilled in the art will appreciate that the herein described embodiments for controlling an engine may also be implemented in a computer program, which, when it is executed in a computer, instructs the computer to execute the method. The computer program is usually constituted by a computer program product 603 stored on a non-transitory/non-volatile digital storage medium, in which the computer program is incorporated in the computer-readable medium of the computer program product. The computer-readable medium comprises a suitable memory, such as, e.g.: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc. The invention is not limited to the above-described embodiments. lnstead, the invention relates to, and encompasses all different embodiments being included within the scope of the independent claims.

Claims

1. A method (200) performed by a control arrangement for controlling a speed of a vehicle (100), the vehicle (100) comprising a regenerative brake system, the method comprising, when travelling downhill, automatically applying a first brake force to control the speed of the vehicle to be maintained at a set speed level, vmax, when this set speed level, vmax, is reached, the method (200) further comprising, when the vehicle (100) approaches the end of a downhill road section (510) while the speed of the vehicle is controlled to be maintained at the set speed level, vmax: adjusting (210) the applied brake force from the first brake force to a second brake force to accelerate the vehicle (100) to an increased vehicle speed, vsch, exceeding the set speed level, vmax, wherein the second brake force is applied by at least the regenerative brake system.

2. Method (200) according to claim 1, wherein adjusting (210) the applied brake force comprises reducing the applied brake force from the first brake force to the second brake force.

3. Method (200) according to any one of the claims 1-2, wherein the second brake force is applied solely by the regenerative brake system.

4. Method (200) according to any one of the claims 1-3, wherein the increased vehicle speed, vsch, exceeding the set speed level, vmax, is based on at least one of: a preset speed level, the set speed level, vmax, and/or a period of time that the vehicle will exceed the set speed level, vmax.

5. Method (200) according to any one of the claims 1-4, further comprising, when adjusting the applied brake force: determining (202) the second brake force allowing the vehicle (100), when applied, to reach the increased vehicle speed, vsch, exceeding the set speed level, vmax, when the vehicle (100) reaches the end of the downhill road section (510), wherein the adjusting (210) of the applied brake force further comprises applying the lO determined second brake force such that the vehicle (100) is accelerated to the increased vehicle speed vsch.

6. Method (200) according to claim 5, wherein the determining (202) the second brake force is at least partly based on one or more of: a road inclination data of the downhill road section (510), a curvature of the downhill road section (510), a weight of the vehicle (100), air resistance force acting on the vehicle (100), and/or a traffic situation within the downhill road section (510).

7. Method (200) according to claim 6, wherein the determining (202) the second brake force is further based on at least one of: a speed of the vehicle in the downhill road section (510), the first brake force applied in the downhill road section (510), and/or a heat development in the regenerative brake system _

8. Method (200) according to any one ofthe claims 1-7, wherein the determined second brake force may change dynamically along the downhill road section (510).

9. Method (200) according to any one of the claims 1-8, further comprising: determining (204) a position in the downhill road section (510) ahead of the vehicle (100) where the applied brake force is to be adjusted to accelerate the vehicle (100) to reach the increased vehicle speed, vsch, exceeding the set speed level, vmax, and adjusting (210) the applied brake force when reaching said position.

10. Method (200) according to claim 9, wherein the determining (204) of the position is at least partly based on a road inclination data of the downhill road section (510).

11. Method (200) according to any one of the claims 9-10, wherein the determining (240) of said position is based on the determined second brake force.

12. Method (200) according to any one of the claims 1-11, further comprising: applying (206) a regenerative brake force prior to the vehicle reaching said lOset speed level, vmax; and controlling (208) a level of said regenerative brake force such that the vehicle reaches said set speed level, vmax, prior to or at the position where the applied brake force is adjusted from the first brake force to the second brake force to further accelerate the vehicle.

13. Method according to any one of the claims 1-12, wherein, prior to adjusting the applied brake force to accelerate the vehicle to an increased vehicle speed, vsch, exceeding the set speed level, vmax, the vehicle speed is maintained at set speed level, vmax, at least partly by means of the regenerative brake system.

14. A control arrangement (120) for controlling a speed of a vehicle (100), the vehicle (100) comprising a regenerative brake system, the control arrangement (120) being configured to, when the vehicle (100) is travelling downhill, automatically apply a first brake force to control the speed of the vehicle to be maintained at a set speed level, vmax, when this set speed level, vmax, is reached, the control arrangement (120) being further configured to, when the vehicle (100) approaches the end of a downhill road section (510) while the speed of the vehicle is controlled to be maintained at the set speed level, vmax; adjust (210) the applied brake force from the first brake force to a second brake force to accelerate the vehicle (100) to an increased vehicle speed, vsch, exceeding the set speed level, vmax, wherein the second brake force is applied by at least the regenerative brake system.

15. A vehicle (100) comprising a control arrangement (120) according to claim 14.

16. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method (200) according to any one of the claims 1 to

17. A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method (200) according to any one of the ciaims 1 to 13.