SE538992C2 - Method and control unit for controlling a regenerative braking system in a vehicle - Google Patents

Abstract

A method and a control unit for controlling a regenerative braking system in a vehicle for which a maximum speed vmm, which the vehicle should not exceed, are defined. According to the present invention, at least one predicted velocity Vpæd for the vehicle is determined. Then, if the at least one predicted speed Vpmd exceeds the maximum speed vmm during the wagon section, the regenerative braking system is activated before an actual speed wax for the vehicle reaches the maximum speed vmm. As a result, braking is obtained for a longer period of time and with lower power than with previous kanda solutions, whereby a larger part of the brake energy can be utilized by the regenerative brake system than with previous kanda systems. Fig. 2

Description

TECHNICAL FIELD The present invention relates to a method for controlling a regenerative braking system according to the preamble of claim / l and a control unit according to the preamble of claim 2ö %%.

The present invention also relates to a computer program and end computer program product which implement the method according to the invention.

Background Vehicles can vary in speed when driven on a single-wave section. These variations in speed may be due, for example, to changes in torque committed by an engine in the vehicle, or to the vehicle accelerating or decelerating due to the wave inclination of the wave section. Vehicles, and then especially heavy vehicles such as trucks, buses or other arbitrary heavy vehicles, typically accelerate on downhills due to heavy train weight M. In the same way, heavy vehicles often decelerate on uphills due to their train weight M.

For many vehicles there is a defined maximum speed vm fl, which the vehicle should not exceed. This maximum speed vmm can be used to avoid the vehicle getting too high a speed, where a too high speed can for example be a single speed that exceeds a speed limit in the pre-section, or a speed that exceeds a maximum permitted speed for the vehicle.

The maximum speed vmm can thus constitute a single-speed limit for a wave section, which the driver does not want to exceed, for example due to the risk of obtaining a marking due to speeding. Typically, the driver 10 brakes the vehicle, for example by using a brake pedal, if the speed of the vehicle exceeds the maximum speed vm fl.

Many motor vehicles today are equipped with cruise control. A goal is to achieve a steady predetermined speed. Cruise control is often performed in vehicles by interlocking systems, a cruise control system, which requires motor torque from an engine system, and a constant speed braking system, which prevents the vehicle from rolling up at too high a speed, especially on downhill slopes.

The cruise control tries to adjust the engine torque to avoid deceleration, or application of braking action, on downhill slopes where the vehicle accelerates by its own weight. An overall goal for the cruise control is to provide a comfortable driving and increased comfort for the driver of the motor vehicle, since the driver does not have to apply gas to pour a speed set speed of the driver selected by the driver. The set speed v fi i is the speed that the driver wants the motor vehicle to pour on a level road and which is set by the driver. The cruise control then provides an engine system in the vehicle set speed v fi m for controlling the engine system. The set speed v fi m is often related to one-speed limitation for a road section where vehicles are located.

A traditional constant speed brake automatically brakes the vehicle when a Down Hill SpeedControl (DHSC) vüwc has been reached. The constant-speed braking speed vmwc is often related to the set-speed v för m the ramp with an offset, in such a way that the constant-speed braking speed vmwc is equal to the set-speed o v fi m plus the offset speed v fi fæt, vüwc = v fi m + v fi fæt. When 10 constant speed braking is used, the maximum speed vmm corresponds to the constant speed braking speed vüwc, vmm = vmwc.

The constant speed brake thus regulates the speed of, for example, heavy vehicles on downhill slopes, as these accelerate on their own weight on the downhill slopes. as a brake when used in a generator mode pre-device. Other types of brakes can also be used by the constant speed brake.

Brief description of the invention For conventional vehicles, constant speed braking or driver-controlled braking, for example with a brake pedal, usually constitutes a complete loss. Constant speed braking and driver crash braking years often related to the above mentioned maximum speed vmm.

For vehicles comprising a regenerative braking system, some of the total braking energy can be recovered. The extent of this recoverable part of the year depends, among other things, on the size of the braking energy and / or the braking energy, as well as on other parameters specific to the regenerative braking system.

In this document, the invention will mainly be described in relation to constant speed braking, but a person skilled in the art realizes that corresponding effects and problems which occur during constant speed braking can also occur during driver crash braking. The principles of the present invention are applied to the edge in essentially all driving cases where it can be allowed to select when the braking action is to be applied. Thus, if it is not critical from a safety perspective exactly when the vehicle is to start braking, so that this time can be controlled by the control unit according to the present invention, then the present invention can be applied. One such application example is downhill braking.

The present invention can be realized on substantially all types of vehicles comprising a regenerative braking system. Vehicles with regenerative braking systems include hybridized vehicles and all-electric vehicles.

A regenerative braking system can be an integral part of a vehicle's driveline. As an example, it can be mentioned here that hybridized vehicles, where an electric machine is controlled in generator mode during braking, whereby the braking energy is at least partially utilized.

Regenerative braking systems may include one or more of a battery, a supercapacitor, a flywheel, a spring, a hydraulic pump cooperating with an accumulator, a pneumatic compressor cooperating with a pressure tank, and a device for transferring energy to a consumer in the vehicle. These devices recover or transfer the energy that is braked away from the braking system. When the energy is transferred to consumers in the vehicle, loads can be controlled to consume the energy during time braking takes place. A well-functioning regenerative braking system can, under favorable conditions, recover a significant part of the braking energy.

Prior art constant speed brakes base their function on how an actual speed wax of the vehicle is related to the constant speed braking speed vüwc in such a way that braking action is applied when the constant speed braking speed vüßc has been achieved. The braking effect then continues to be applied so that the constant speed braking speed. These braking often means that relatively large energy is slowed down under high power, which is seldom optimal from a regeneration perspective. In other words, previously known constant-speed brakes can waste away energy, because the energy is slowed down with such a high effect that not all of this braking energy can be taken care of by the regenerative braking system, which means that traditional braking systems must also be used. Thus, the level of power to be taken care of by the regenerative braking system in previously known systems is not optimal for regeneration.

There are mainly two reasons why high effects are not optimal for regeneration. One reason is that the regenerative braking system has a maximum power, which means that conventional braking systems must be used if the required braking power is higher than this maximum power. Another reason is that the efficiency of regeneration is lower at higher effects.

Taken together, today's known constant-speed braking systems provide non-optimal regeneration in the braking system, as they do not take into account regeneration-related properties of the driveline and / or braking system.

It is therefore an object of the present invention to provide a control which provides a more energy efficient regenerative braking system.

This object is achieved by the above-mentioned method for controlling a regenerative braking system according to the characterizing part of claim 1. The object is also achieved by the above-mentioned control unit according to the characterizing part of claim Qêåå, and by the above-mentioned computer program and computer program product.

The invention thus relates to the control of an LQw regenerative braking system in a vehicle, for which a maximum .. .- '* +' 'É' ha - --.- w ': llLL f) L, ... qiiv, X '111533; f V _ ..

P 'ken said vehicle should not exceed, there is lO 1 aefined. A control unit performs the steps of: "determining at least one predicted speed for said vehicle" for a section of road which extends immediately in front of said vehicle, and "if said at least one predicted speed vpaa would exceed said maximum speed which" during said no braking occurs, activating said vehicle in said maximum regenerative braking system comprises one or more devices which recover or transfer the energy braked away by WO Ill (I) si * 1. / "fstemet, and wherein the activation of said regenerative most active O" i 'J Crom ~ sy em. optimized based on the capacity of the regenerative J brake system for energy recovery.

The present invention controls when, i.e. at what time / position, the regenerative braking system is activated to provide a favorable regeneration in the driveline. If this time / position is selected according to the invention, this time / position is postponed compared to previously known systems, which means that the braking can take place for a longer period of time. This reduces the average effect of braking, as the energy to be braked is distributed over a longer period of time. In this way, the regeneration takes place at a lower average power, whereby a larger part of the braking energy is edged by the regenerative braking system compared to previously known systems. Thus, the control of braking is adapted to the possibilities of the regenerative braking system allowed to recover the braking energy. In other words, the regeneration is optimized based on the regenerative properties of the regenerative braking system 10 to enable a higher degree of energy recovery.

Utilizing a lower braking power, i.e. by braking over a longer period of time according to the invention, means that a major part of the braking can be done with the regenerative braking system compared to previously known braking with higher braking power. This is advantageous because no energy is recovered when braking with traditional braking systems. Even lower fuel consumption is obtained with the present invention, since the recovered energy can later be used for underloading, for example an internal combustion engine in the vehicle, or for driving other consumers in the vehicle.

The present invention can thus take care of and utilize a larger part of the total braking energy with the regenerative braking system than previously known systems, since a larger part of the braking power is below the maximum power for the regenerative braking system. Although the braking power with prior art brake control is below the maximum power of the regenerative braking system, the efficiency of the regenerative braking system may increase if the present invention is utilized. Thus, a major portion of the braking energy is taken by hand by utilizing the present invention, both for braking effects above and below the maximum power.

The time / position for activating the braking action can in favorable cases be chosen so that the regenerative braking system can utilize essentially all braking energy. As a result, essentially no energy is wasted on pure deceleration of the energy, since essentially no traditional braking systems are used to slow down the vehicle's speed.

In addition, a slow average speed, which is the result of an extension of the braking period according to the invention, also has the effect that the air resistance to the vehicle becomes lower. This means that less energy is slowed down by the air resistance, which in turn allows more energy to be slowed down by the regenerative braking system. As a result, a larger part of the braking can be done by the regenerative braking system when there is an opportunity to recover the energy. Some of the energy previously braked by the air resistance can therefore be recovered through the regenerative braking system of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further elucidated below with reference to the accompanying drawings, in which like reference numerals are used for like parts, and in which: Figure 1 shows a flow chart incorporating the method of the present invention, Figure 2 shows an example of a driving case, Figure 3 shows an example on a driving case, Figure 4 shows an example of a driving case, and Figure 5 shows a control unit.

Description of Preferred Embodiments Figure 1 shows a flow chart incorporating the method of the present invention. In a first step 101 of the method, at least one predicted speed vpæa is determined, which the vehicle is predicted to follow during a wave section. The at least one predicted speed vpæd is thus determined for a period of time which the vehicle will spend the peacock section. The wave section propagates closest in front of the vehicle and may, for example, have a length L which is 100 000 meters, or may have another arbitrary suitable length. The determination of the at least one predicted velocity may here be determined in a number of ways, and based on a number of parameters. which will be described in more detail below.

For the vehicle, there is a maximum speed vmm defined which the vehicle should not exceed. In a second step 102 process of the present invention, a regenerative braking system is activated in the vehicle if the at least one predicted speed vpæd exceeds the maximum speed vm fl during the road section, and the activation of the regenerative braking system according to the invention takes place before the vehicle actually reaches the maximum speed. In a third step 103 of the process, braking energy is recovered in the regenerative braking system when braking action is applied.

Thus, in the second method step 102, it is analyzed whether the at least one predicted speed vpæd determined in the first method step will exceed the maximum speed vmm below the road section. If this happens then compare the actual speed the wax vehicle is driven with and the maximum speed vmm to determine when the actual speed wax vehicle will reach up to the maximum speed vm fl. Then the regenerative brake system is activated before the actual speed waxes when the maximum speed vmn.

In prior art systems, only the actual speed wax has been compared with the maximum speed vm fl, and when the actual speed wax has exceeded the maximum speed vmm, braking has been activated. According to the present invention, it is instead first identified whether braking will be relevant based on the predicted speed vase.

This knowledge is then used to advance the activation of the regenerative braking system compared to previously known systems, i.e. to select a single activation position Pmqw, which occurs before the actual speed waxes when the maximum speed vm fl. This achieves braking over a longer period of time, which results in a lower braking effect during braking and thereby a larger part of the braking energy can be utilized by the regenerative braking system than with previously known systems.

The prior art method and the method of the present invention are schematically illustrated in the unrestricted example of Figure 2. A vehicle here arrives at a downhill at a first position P1. According to prior art solutions, the actual speed would increase on the downhill slope due to the vehicle weight M of the vehicle, until it reaches the defined maximum speed vmm at a second position P2. Only when the actual speed væïgæa flfl when the defined maximum speed vmm is activated according to previous solutions braking. Then the actual speed væïgfa flfl remains at the level of the maximum speed vm fl until the downhill slope is passed at a third position P3 and the vehicle starts to lose speed again. The vehicle is finally back to its original speed at a fourth position P4. According to the prior art, the vehicle is braked here between the second position P2 and the third position P3.

According to the present invention, the at least one predicted speed vpæd for the road section in front of the vehicle is determined. The predicted speed vpæd is then analyzed to see if it will exceed the maximum speed vmm if no braking takes place. In this example it is found that the predicted speed vpæd would l0 ll exceed the maximum speed vm fl at the second position P2 if no braking is performed. Therefore, according to the invention, the braking will be activated in one activation position Pmqw, which is before the second position P2 when the actual speed according to the invention wax would have reached the maximum speed vmm if no braking had been performed. According to the invention, the braking effect is applied until the third position P3 is reached. At the solitary position Pcmmm, which is after the second position P2, the actual velocity according to the invention wax coincides with the previously known actual velocity Vact_regular - As shown in Figure 2, the actual velocity of the present invention will be below the actual velocity of the prior art solutions. Pmgal to the merging position Pcmmm, which means that the average speed of the actual speed wax according to the present invention is lower than the actual speed væïaæan ï according to previous candle solutions. The braking action is applied with the present invention from the activating position Pn fl a to the third position P3, which prolongs the braking time by the interval between the activating position Pmgal and the second position P2 compared with prior art. This means that the braking takes place over a longer distance / time period and with a lower braking effect than for previously known solutions.

As a result, the braking effect can be regulated to a level that is favorable for regeneration with the regenerative braking system, whereby a larger part of the braking energy can be utilized by the regenerative braking system than with previously known systems. Here and in this document, the invention has been described with the aid of positions, such as positions P1, P2, P3, P4, Pmqw, and Pcmmm. However, it will be appreciated by those skilled in the art that these positions have equivalents in times.

The magnitude of the maximum speed vm fl can be determined in several different ways. If the vehicle is equipped with a cruise control, where for example the driver sets a desired set speed wax, the maximum speed vmm can have a magnitude that is related to the set speed vxl. According to an embodiment of the invention, the maximum speed vm kan may exceed the set speed selection by a number of X percent, vmax == wet * (14-åš).

Since the driver often sets the set speed related to a one-speed limit for the road section, the maximum speed vm fl here is also often indirectly linked to a speed limit for the road section.

According to one embodiment of the invention, the maximum speed vmm is related to a constant speed braking speed vüßc for a constant speed brake in the vehicle. The maximum speed can here be set equal to the constant speed braking speed sharp, i.e. vm fl = sharp. Hereby the embodiment provides a connection to the constant speed brake and its utilization on downhill slopes.

The size of the maximum speed vm fl can also be product-related to how the driver behaves when he drives the vehicle. For example, if the driver often starts to brake the vehicle at a certain driver-dependent speed vm fi mïmjwí in downhill slopes, the system learns that the maximum speed vm vmm = vm fi mïm fi wx. The system is adapted here according to the driver's behavior and if the driver, for example, starts to brake at a lower speed in 10 l3 downhill slopes than before, the maintenance of the driver - dependent speed vm fi mïm fi wx will decrease.

According to one embodiment, the magnitude of the maximum velocity vm år is related to what the wave section and / or the traffic on it looks like. Thus, one or more properties of the wave section determine the size of the maximum speed vmm, as such properties may include a single speed limit, or a curvature of the wave section. In addition, the properties may include the presence or absence of or several speed cameras and how the traffic situation is in the wave section. on the wave section or not.

Since the maximum speed vmm is related to ambient traffic on the wave section, radar can be used to determine the speed of and / or a distance to a vehicle in front. Then the maximum speed vmw can be determined in such a way that the vehicle does not risk driving into, or getting too close to, the vehicle in front. Radar is used, among other things, by adaptive cruise control (ACC), which means that radar information is available in vehicles equipped with such adaptive cruise control. Therefore, the contribution in complexity becomes very modest for this embodiment.

According to an embodiment of the invention, the maximum speed vmm can vary in size during said wave sections. Medandra words are the maximum speed vmm dynamic. Size at the maximum speed vm hår hair can be a function of, for example, the time or positions in the wave section. The maximum velocity vmm can then, for example, consist of a single vector with possibly different care corresponding to different times / positions. According to an embodiment of the present invention, the predicted velocity vpæd is determined based on a knowledge of the wave section. This knowledge may be based on one or more depositional information, such as GPS information (GlobalPositioning System information), map information, topography information, weather reports, information communicated between different vehicles and information communicated by radio, and may consist of knowledge of prevailing topography, curvature, traffic situation, wave work, traffic intensity and waveform. Furthermore, the knowledge can consist of a speed limit for the upcoming wave section, as well as a traffic sign in connection with the wave. Today, many vehicles include systems, such as navigation systems and cruise control systems, which utilize such information. Therefore, this embodiment can be implemented with a low addition in complexity in vehicles where the information is already available.

Figure 3 shows a non-limiting example of utilizing knowledge of the wave section for the same driving case as shown in Figure 2. The actual speed Væmaæau fl and braking sand according to prior art corresponds to that described for Figure 2 OVäfl.

According to the embodiment of the present invention, when the knowledge of the wave section is present, it is determined at least one predicted speed vpæd taking into account this knowledge. The predicted velocity vpæd corresponds in the figures in roughly the curve to the actual velocity væïJæ @ u fl according to prior art. Since the control unit as the determinant of the predicted velocity vpæd then has very good knowledge of what the wave section looks like in the future, a very accurate determination of the predicted velocity vpæa can be made. Based on this very accurate predicted velocity vpæd, the braking can be determined so that the energy recovery regeneration system maximize at the same time as the vehicle pours a suitable actual speed vami end of the downhill. In addition, braking can start earlier because the control unit can predict with great certainty that the actual speed of wax will exceed the maximum speed vmm if no braking takes place.

This is illustrated in the example in Figure 3, where the at least one predicted speed vpæd for the road section in front of the vehicle is determined and analyzed to see if it will exceed the maximum speed vmm if no braking occurs. The predicted velocity vpæd here corresponds, as mentioned above, largely to the curve of the actual velocity væïJæ @ u fl according to prior art. Since the control unit knows that the predicted speed vpæd is reliable, it can already apply the braking effect at the beginning of the downhill slope, i.e. at the first position P1. Thus, the activation position Pmqw coincides with the first position P1, Pmqw = P1, which is located before the second position P2 when the actual speed according to the invention wax would have the night maximum speed vmm if no braking were applied. The second position P2 is also the position that previously known solutions would have started to apply brake effect. According to this embodiment, therefore, braking action can be applied directly when the vehicle begins to accelerate downhill, since this acceleration based on the knowledge of the road section can easily be predicted to reach the maximum speed vmn.

According to the invention, braking action is applied until the third position P3 is reached. In this example, the third position P3 coincides with the concomitant position Pcmmm, Pcmmm = P3, at which the actual speed according to the invention 16 Val and the previously known actual speed væïgsa ï coincide again.

As can be seen from Figure 3, the actual velocity essentially the present invention is below the actual velocity waveform fl according to prior art solutions for a relatively long time, from the activating position Pmqw to the merging position Pcmmm. As a result, the average velocity of the actual velocity wax according to the present invention is lower than the average velocity of the actual velocity vial fl according to previously known solutions during the same period, which begins at the first position P1 and ends at the third position P3.

The braking action is applied with the present invention from the activation position Pn fl to the third position P3, which prolongs the braking distance / braking time by the interval between the first time position P1 and the second position P2 compared to the prior art. This means that braking takes place over a longer period of time and thus at a lower braking effect, whereby a larger part of the braking energy is edged out than for previously known solutions. In addition, the braking can be controlled with high precision so that the maximum speed is reached just when the downhill slope ends to maximize the fuel savings for the vehicle.

According to an embodiment of the present invention, a single velocity profile vp fl f extending from an actual velocity wax, for example the actual velocity wax at the first position P1, is determined to the maximum velocity vmm, for example at the third position P3. In the example of Figure 3, then, the velocity profile vp fl f could correspond to the dashed line of the actual velocity wax of the present invention between the first P1 and third P3 17 positions. Thus, the appropriate velocity profile vmwf here can first be determined, after which the activation of the regenerative brake system is made based on the velocity profile vmwf. The appropriate shape of the speed profile vpnf may depend on which parameter is to be optimized, for example it may depend on fuel economy, on regeneration, on driver acceptance, on co - traffic acceptance, and / or on driver comfort.

According to one embodiment, the velocity profile vp fl f is determined so that the resulting braking effect has a value which is within a favorable interval for the regeneration of the regenerative brake system. For example, here a certain braking system may have a maximum regeneration power corresponding to a first braking power limit value, the speed profile according to the embodiment being determined so that the resulting braking power is below this braking power limit value.

There are strategic speedometers, such as the “LookAhead” speedboat (LACC), which utilize knowledge of existing road sections, ie knowledge of how roads will look in the future, to determine the appearance of the single reference speed vn; which in such cruise control provides an engine system in the vehicle for controlling a torque request from the engine. In strategic cruise control, the reference speed is allowed to, within a speed range, differ from the set speed chosen by the driver in order to achieve a more fuel-efficient driving based on knowledge.

The knowledge can be used by the LACC in a variety of ways. For example, knowledge of an upcoming speed limit can be used in advance to achieve fuel-efficient speed reductions before an upcoming lower speed limit.

Correspondingly, knowledge of, for example, an upcoming 18 roundabout or intersection can also be used to slow down in front of the roundabout or intersection in a well-efficient manner.

For example, a LACC allows the reference velocity vmf to rise above a steep uphill slope to a level which is well above the set speed, since the motor vehicle is likely to lose speed on the steep uphill slope due to high train weight relative to the vehicle engine performance. Correspondingly, the LACC allows the reference speed vn fi to be lowered to a level which is below the subset speed vgm in front of a steep downhill slope, since the motor vehicle is assumed to accelerate on that steep downhill slope due to the high train weight. The idea is that it will be more fuel-efficient to take advantage of motor vehicle acceleration due to its own weight on the downhill slope, first accelerating in front of the downhill slope and then braking downhill. In this way, LACC can reduce fuel consumption while largely maintaining driving time.

Figure 4 shows a non-limiting example of how one embodiment of the present invention may interact with a LACC. The actual speed and braking speed of the prior art correspond to that described in Figures 2 and 3 above. Those skilled in the art will recognize that the invention, in addition to the downhill case shown in Figure 4, may also be utilized in connection with other speed changes initiated by the LACC.

According to the embodiment of the present invention, when the knowledge of the wave section is present, and a collaboration with LACC is utilized, the predicted speed is determined with regard to the knowledge LACC possesses. As mentioned above, in some cases the LACC lowers the reference speed vnf to a level below the set speed well, for example facing a downhill slope, as it reduces the need for conventional braking and is fuel efficient.

If the LACC indicates that it intends to reduce the actual speed of wax, for example before a downhill slope, such as, as shown in Figure 4, the braking action is applied in a deactivation position Pmgal already before the descent begins in the first position P1. Thus, regeneration can be performed by the regenerative braking system when the lowering of the actual speed wax is done before the downhill slope, which makes the braking time extended further. Compared with previous candle solutions, by using this embodiment of the invention, the braking time and the braking distance are extended by the interval from the activation position Pmgal to the second position P2 when the previous candle solutions had started to brake.

Then the regeneration can continue for the braking below the entire downhill until the actual speed wax according to the present invention reaches the maximum speed vmm and also coincides with the actual speed Væmafau fl according to the prior art solution in the third position P3 at the end of the downhill, when P3 = PCOTÛIHOH 0 Figure 4 shows the actual velocity of the present invention at a level below the actual velocity of the prior art solutions for a long time, from the first position P1 to the merging position Pcmmm. As a result, the average velocity, and also the braking effect, of the actual velocity wax according to the present invention is lower than the average velocity of the actual velocity Væmafau fl according to previously known solutions during the same period. In addition, regeneration can be performed from the fact that the actual velocity wax according to the LACC allows to set the set velocity vm in the activation position Pmqw, which occurs before the descent begins in the first position P1.

The braking according to this embodiment therefore takes place over a longer distance and time period and gives a lower braking effect, whereby a larger proportion of the braking energy can be utilized on the regenerative braking system than with previously known solutions.

According to an embodiment of the present invention, it is assumed that the predetermined speed at which the slope of the carriageway during the section of the carriage is substantially equal to the carriageway inclination of the vehicle when the carriage is carried out. For this embodiment, there is no requirement for the vehicle to have access to map information, positioning information and / or topography information, since the vagal slope where the vehicle is located can be determined in another way, for example based on an accelerometer, or on a force equation. The slope of the vehicle is also accessible in the vehicle, as it is used by other systems, such as pre-axle selection systems or the like. Therefore, this embodiment often adds a limited amount of complexity to the vehicle.

According to an embodiment of the present invention, the determination of the predicted speed vpæa is based on the actual speed wax and on an actual acceleration in front of the vehicle. Then it is analyzed how close the vehicle's actual speed is to the maximum speed vm fl, and how fast the vehicle approaches the maximum speed vm fl.

The activation position Pmaw is then also determined based on a difference between the actual speed wax and the maximum 21 speed vmm, as well as on an actual acceleration aaü the vehicle. For example, it may be considered appropriate that the applicator braking effect on the vehicle's actual speed wax is relatively close, and also fast approaches the maximum speed Vmax - According to an embodiment of the present invention, the determination of the at least one predicted speed v is based on an assumption that the fuel supply to the engine is restricted for parts or the entire wave section. The predicted speed vpæd is based on an engine brake simulation, the bad engine torque is based on a slackening of the engine, that is to say on a slackening torque curve for the engine.

According to an embodiment of the present invention, the determination of the at least one predicted speed is based on an assumption that the vehicle freewheels for parts or the entire wave section. The simulation of the predicted speed vpæd is based on a freewheel simulation, the fool vehicle is allowed to roll freely with open clutch and / or neutral gear. When the vehicle is freewheeling, no power is transmitted from the engine to the drive wheels.

During cruise control, the driveline torque, ie the driving torque of the saw vehicle, is regulated by a speed controller in the vehicle, when the speed controller receives the setpoint pre-speed from the cruise control logic. For traditional cruise control, the set speed is such a setpoint. Procedures when the reference speed vn fi is allowed to deviate from the offset speed v fi i, such as, for example, LACC, constitute the reference speed vn fi this setpoint.

According to an embodiment of the present invention, the determination of the at least one predicted speed vmæd is based on a cruise control simulation performed in the vehicle, where the cruise control simulation is based on a speed setpoint. The lapse when the vehicle is driven with the cruise control switched on, the then speed setpoint in the simulation can be based on the set speed v fi m for the cruise control.

The setpoint maintenance can also be based on the vehicle's current actual speed wax, or on an estimate of a driver's desired actual speed wax. By this embodiment, accurate estimation of the at least one predicted speed vpæd is obtained even when cruise control driving is not applied in the vehicle, i.e. when accelerating pedal driving.

According to an embodiment of the invention, the activation position Pmg is determined to a position when the vehicle accelerates and when it is determined that the predicted speed vpæd will exceed the maximum speed vmm. An example of such an activation position Pmqw is shown in Figure 2, when the vehicle is on a downhill slope and accelerates due to its train weight, while it can be established that the predicted speed vpæd will exceed the maximum speed vm fl.

According to an embodiment of the present invention, the position activating position Pmaw, i.e. the position when the regenerative braking system is activated, to the position when the vehicle has an excess of power and when it is determined that the predicted speed vpæd will exceed the maximum speed vmm. A vehicle is considered hairy and in this document has excess power if it accelerates without fuel supply to the engine. An example of such an activation position Pmqw is shown in Figure 2, when the vehicle is on a downhill slope and accelerates due to its train weight.

According to an embodiment of the invention, the activating position Pmg fi l is determined to a position from which the maximum speed vm fl is calculated to be achievable during the road section by utilizing a braking energy which can be achieved with the regenerative braking system. An example of such an activating position Pmqw is shown in Figure 3, where in the first position P1 it is determined that the velocity profile vmwf can be realized by braking with the regenerative braking system so that the maximum speed vm is reached below the road section, for example at the third position P3.

According to one embodiment of the present invention, the activation of the regenerative braking system is based on an adaptive algorithm. This algorithm analyzes how much braking energy needs to be braked away, where this braking energy dynamically changes during the vehicle's progress, partly due to the vehicle's speed and on the road slope. Based on this dynamically changing braking energy, it is then adaptively calculated which braking effect is to be applied to decelerate this braking energy.

The adaptive algorithm can here be based on at least one prediction of a braking process vmsajm fl e for the vehicle. the braking action applied near the prediction of the braking process vmßaimne is made. According to another embodiment, the prediction of the braking process vmsaß flfl changes dynamically during the braking itself. According to another embodiment, the predicted braking process is determined based on a pre-calculated braking effect, where this pre-calculated braking effect has been calculated based on an appropriate braking effect to apply, where the suitability is judged based on a braking energy that needs to be braked away. lO 24 If the prediction of the braking process vm @@ ¿m, e, that is to say the prediction of how the actual speed wax for the said vehicle will be changed by the determined suitable braking effect, will reach up to the maximum speed vmm the braking effect is increased, i.e. the increased braking torque / braking torque. If instead the prediction of the braking process vm @@ ¿m fl e shows that the actual speed at which the vehicle will not reach the maximum speed vmm, the braking effect is reduced, ie the braking torque / braking effect is reduced. The increase and / or decrease of the braking effect can be determined here based on how close to the maximum speed mmxprediction of the braking process vm @@ ¿m fl e when. This results in regulation which just reaches the maximum speed vmm at the end of the downhill slope.

Thus, according to these embodiments of the invention, control of the braking system during braking itself can be obtained, which results in a dynamic and more favorable regeneration with the regenerative braking system, since the braking effect can be regulated to a level which is more favorable for regeneration.

Those skilled in the art will appreciate that a method of controlling a regenerative braking system according to the present invention may additionally be implemented in a computer program, which when executed on a computer causes the computer to perform the method. The computer program usually consists of a computer program product 503 (shown in Figure 5) stored on a digital storage medium, where the computer programmer is included in a computer program product's readable medium. The computer readable medium consists of a suitable memory, seasonally for example: ROM (Read-Only Memory), PROM (Programmable Read). Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk drive, etc.

Figure 5 schematically shows a control unit 500. The control unit 500 comprises a computing unit 501, which may be essentially any suitable type of processor or microcomputer, e.g. a Digital SignalProcessor (DSP), or an Application Specific Integrated Circuit (ASIC). The computing unit 501 is connected to a memory unit 502 arranged in the control unit 500, which provides the computing unit 501 e.g. the stored program code and / or the stored data the computing unit 501 needs to be able to perform calculations. The calculation unit 501 is also arranged to store partial or final results of calculations in the memory unit 502.

Furthermore, the control unit 500 is provided with devices 511, 512, 513, 514 for receiving and transmitting input and output signals, respectively. These input and output signals may include path shapes, pulses, or other attributes, which the input signals receiving devices 511, 513 are detected as information and may be converted into signals which can be processed by the computing unit 501. These signals are then provided to the computing unit 501. The output signal devices 512,514 are arranged to convert signals obtained from the computing unit 501 for creating output signals by e.g. modulate the signals, which can be transmitted to other parts of the vehicle.

Each of the connections to the devices for receiving and transmitting input and output signals, respectively, may be one or more of a cable; a data bus, such as a CAN bus (Controller Area Network bus), a MOST bus (Media OrientatedSystems Transport bus), or any other bus configuration; or by a wireless connection. According to one aspect of the invention, there is provided a system comprising a control unit which is arranged for controlling a regenerative braking system in a vehicle. The control unit comprises a prediction unit, which is arranged to determine at least one predicted speed vpæd for the vehicle for one-wave section. This determination can be performed on a plurality of different methods according to the above-described embodiments method, the prediction unit being arranged so that it can perform the predictions according to the respective embodiment.

The control unit also comprises an activating unit, which is arranged to activate the regenerative braking system in the vehicle before an actual speed wax for the vehicle reaches the maximum speed vmm and if it at least one predicted speed vpæd exceeds the maximum speed vm fl below the wave section.

The control unit, and thus the system, according to the present invention has the same advantages as stated above for the methods according to the invention.

One skilled in the art will appreciate that the above-mentioned computer may be the subdivision unit 501 and that the above-mentioned memory may be the memory unit 502.

The person skilled in the art also realizes that the above system can be modified according to various embodiments of the method according to the invention. In addition, the invention relates to a motor vehicle 1, for example a single truck or a bus, comprising at least one control unit for controlling a regenerative braking system according to the invention.

The present invention is not limited to the above-described embodiments of the invention but relates to and includes all embodiments within the scope of the appended independent claims.

Claims (28)

1. A method of controlling a regenerative braking system in a vehicle for which a maximum speed mmx, which said vehicle should not exceed, is defined, characterized in that a control unit performs the steps of: - determining at least one predicted speed vpæd for said vehicle for a road section; and - if said at least one predicted speed v exceeds said maximum speed vmm during said road section, activating said regenerative braking system before the actual speed grows for said vehicle reaches said maximum speed mmx, where the regeneration is optimized based on the regenerative braking system regenerative properties. A method according to claim 1, wherein said road section comprises a downhill slope in which said vehicle accelerates due to a train weight M of the vehicle. A method according to any one of claims 1-2, wherein said maximum speed vm fl corresponds to a constant speed braking speed vwßc, mmx = vmßc, at which a system of constant speed braking brakes the vehicle. A method according to any one of claims 1-2, wherein said maximum speed vm fl is related to a set speed wet of a cruise control. A method according to any one of claims 1-2, wherein said maximum speed vmm is related to a preparatory behavior. A method according to any one of claims 1-2, wherein said maximum speed vmm is related to ambient traffic for said road section. lO A method according to any one of claims 1-2, wherein said maximum speed vmm is related to a property of said road section. A method according to claim 7, wherein said feature comprises at least one in the group of: - a speed limit for said road section; - a curvature for said road section; - a presence of at least one speed camera at said road section; and - a traffic situation within said road section. A method according to any one of claims 1-8, wherein said maximum speed vm fl can be changed dynamically during said road section. A method according to any one of claims 1-9, wherein said road section extends immediately in front of said vehicle. A method according to any one of claims 1-10, wherein a knowledge of said road section is used in said determination of said at least one predicted speed vpmd. A method according to claim 11, wherein said knowledge is based on at least one information in the group of: - positioning information; - map information; and - topography information. A method according to any one of claims 1-10, wherein one-way slope said vehicle experiences when said determining said at least one predicted speed vpmd is performed in said determining of said at least one predicted speed vpmd. A method according to any one of claims 1-10, wherein said determining said at least one predicted velocity vpmd is based on an actual velocity wax for said vehicle and on an actual acceleration aex for said vehicle. A method according to any one of claims 1-14, wherein said at least one predicted speed Vpma is determined based on an assumption that a fuel supply to a single engine in said vehicle is restricted for at least a part of said road section. A method according to any one of claims 1-15, wherein said at least one predicted speed vpmd is determined based on an assumption that said vehicle freewheels during at least a portion of said road section. A method according to any one of claims 1-15, wherein said at least one predicted speed vpwd is determined based on a cruise control simulation. A method according to any one of claims 1-17, wherein said activating said regenerative braking system is performed at a position in the group of: - an activating position Pmg fi u at which it is determined that said at least one predicted speed vpmd will exceed said maximum speed vmm and at which said vehicle accelerates; an activating position Pmgw, in which it is determined that at least one predicted speed vpæd will exceed the maximum speed VM 'and in which said vehicle has an excess of power, said vehicle accelerating without an engine in said vehicle supplying fuel; and - an activating position Pmg fl u from which said maximum speed vm fl is calculated to be reachable under said road section by means of a braking energy which can be realized with said regenerative braking system. A method according to any one of claims 1-18, wherein said activation of said regenerative braking system is done based on a speed profile vpmf, which extends from the actual speed wax of said vehicle to said maximum speed vm fl. A method according to any one of claims 1-18, wherein the activation of said regenerative braking system is done based on an adaptive algorithm, which adaptively calculates a suitable braking action to apply based on a braking energy which needs to be braked away. The method of claim 20, wherein said adaptive algorithm comprises a prediction of a braking progression for said vehicle, which depends on said suitable braking action. A method according to claim 21, wherein said suitable braking action is increased if said prediction of said braking process v¿æ @ prMß reaches said maximum speed VITIEiX ° A method according to claim 21, wherein said suitable braking action is reduced if said prediction of said braking process vpæ¿prÜe is constantly lower than said maximum speed mmx. A method according to any one of claims 21-23, wherein said predicted braking sequence vpm @ ¿r fl e is based on a group of: - a current braking action; - a braking effect varying during braking; and - a pre-calculated braking action, which is based on a suitable braking action to be applied, wherein an assessment of said braking action is suitable based on a braking energy which needs to be braked away. A method according to any one of claims 1-24, wherein said regenerative braking system comprises at least one device in the group of: - a battery; - a supercapacitor; - a flywheel; - a feather; - a hydraulic pump cooperating with an accumulator; - a pneumatic compressor cooperating with a pressure tank; and - a device for transferring energy to consumers in said vehicle. A computer program comprising program code, said program code being executed in a computer causing said computer to perform the method according to any one of claims 1 to 25. A computer program product comprising a computer readable medium and a computer program according to claim 26, wherein said computer program is included in said computer readable medium. A control unit arranged for controlling a regenerative braking system in a vehicle, for which a maximum speed mmx which said vehicle should not exceed, is defined, characterized by: - a prediction unit, arranged to determine at least one predicted speed vpæd for said vehicle for one-way section; and - an activating unit, arranged that, if said at least one predicted speed vpmd exceeds said maximum speed vm fl during said road section, activating said regenerative braking system before an actual speed wax said vehicle reaches said maximum speed vmm there regeneration is optimized based on the regenerative braking system.