DE102019212941A1 - Method for controlling a state of charge of a battery of a motor vehicle - Google Patents

Abstract

A method for controlling a state of charge of a battery (314) of a motor vehicle (302), wherein the motor vehicle (302) has a drive motor (310) and an on-board network with the battery (314) that can be charged by means of the drive motor (310), with a Setpoint value for a future point in time is determined taking into account at least one first boundary condition, the state of charge of the battery (314) enabling a predetermined operation of the motor vehicle (302) with the drive motor (310) switched off, and the state of charge of the battery (314) below Consideration of at least one second boundary condition is controlled in such a way that this target value is reached at the future point in time, so that predictive energy management is carried out in the electrical system of the motor vehicle (302).

Description

The invention relates to a method for controlling a state of charge of a battery of a motor vehicle, and an arrangement for carrying out the method.

State of the art

Consumers and energy stores, such as batteries, are provided in on-board networks of motor vehicles. When operating the motor vehicle, it must be ensured that the energy stores always have sufficient energy stored so that the consumers can be safely supplied with energy. For example, it should be ensured that the internal combustion engine of a motor vehicle can be started safely, even after longer periods of rest in which consumers may have to be supplied. This is important both in motor vehicles with internal combustion engines, including hybrid vehicles, which as a rule have a battery-electric starter or starter. In the case of battery-electric vehicles, enough energy should be available in the traction battery at the start of the journey, thus ensuring a remaining range that the next charging station can be safely reached.

A measure of the amount of energy stored in a battery is the battery's state of charge, which is also known as the SoC (state of charge). This can be determined and controlled or checked in a simple manner. On the one hand, it should be noted that the SoC is sufficiently high to withstand longer periods of rest during which there is no possibility to charge the battery and, on the other hand, that the SoC is not too high to have a sufficiently high recuperation potential.

A predictive energy management in an on-board network is primarily used to control the charge state or states of one or more batteries in such a way that the requirements mentioned are met.

It has been shown in particular that the charging strategy of a permanent maximum state of charge has disadvantages in terms of overall fuel consumption compared to charging strategies with a variable SoC.

The reason for this lies in the unused possibility of being able to operate the internal combustion engine at optimum operating points through a variable generator load. Depending on the current operating point of the internal combustion engine, there is the possibility of a consumption-optimized load point shift of the internal combustion engine by means of a variable generator load.

But there is also a significantly fluctuating state of charge of the battery with the result that the state of charge after switching off the internal combustion engine, e.g. B. at the weekend, insufficient electrical energy to supply the electrical consumers and to start the internal combustion engine could be available.

If the SoC falls below a minimum, the combustion engine should be started in order to supply the electrical loads via the generator and to recharge the battery (ies). The minimum charge level of the battery must still be able to guarantee that the internal combustion engine can be started by means of the electric starter, a starter or an electric machine. The internal combustion engine when idling not only worsens the fuel consumption balance, but also causes exhaust gases, including nitrogen oxide, CO ₂ and fine dust, and noises which, depending on the parking situation, can be extremely annoying for the surroundings.

Disclosure of the invention

Against this background, a method with the features of claim 1 and an arrangement according to claim 9 are presented. Embodiments emerge from the dependent claims and from the description.

The method presented is used to control a state of charge of a battery of a motor vehicle in order to carry out predictive energy management in an on-board network of a motor vehicle.

The method described enables an effective control of the state of charge of a battery of a motor vehicle, with particular requirements of certain vehicle types, such as, for example, trucks for local traffic, distribution traffic or long-distance traffic being taken into account. In order to make this possible, numerous boundary conditions were taken into account for the first time, which will be discussed below.

Driving resistances

$${\text{F}}_{\text{ges}}=\text{mg}\mathrm{\mu }\text{cos }\mathrm{\alpha +}\text{mgsin }\mathrm{\alpha +}\text{ma}+\text{cwA }\mathrm{\rho }/2{\left(\text{V}-{\text{V}}_0\right)}^2+{\text{F}}_{\text{Br}}$$

The driving resistances with regard to vehicle propulsion are the sum of rolling resistance F _Ro , gradient resistance Fst, acceleration _{resistance F Be} , air resistance F _Lu and braking _{resistance F Br} . The following applies: $${\text{F.}}_{\text{total}}={\text{F.}}_{\text{Ro}}+{\text{F.}}_{\text{St.}}+{\text{F.}}_{\text{Be}}+{\text{F.}}_{\text{Lu}}+{\text{F.}}_{\text{Br}}$$

$${\text{F.}}_{\text{total}}=\text{mg}\mathrm{\mu }\text{cos}\mathrm{\alpha \; +}\text{mgsin}\mathrm{\alpha \; +}\text{ma}+\text{cwA}\mathrm{\rho }/2{\left(\text{V}-{\text{V}}_0\right)}^2+{\text{F.}}_{\text{Br}}$$

With forward-looking knowledge or estimates of the driving resistances, load requirements can be estimated or calculated in a forward-looking or predictive manner by quasi backward simulation.

Electronic horizon (EH) (far or wide horizon)

An electronic horizon is understood to mean, in particular, road gradient and curve curvature, the legal speed limit, but also additional attributes such as intersections, traffic lights, number of lanes, tunnels, etc. Depending on the current driving position, these are determined as fixed attributes along the route ahead. The electronic horizon is provided by the so-called Horizon Provider (HP), which z. B. can be part of a navigation system. The future route selection of the driver can be determined on the basis of his inputs for the route guidance of the navigation system. Without route guidance, a “most probable path” is usually also transmitted, which is determined on the basis of the underlying road classes or on the basis of statistics on routes that have already been driven. Optionally, the HP determines alternative routes that the driver could also choose. In the following, the term “MPP” (most probable path) is used for the most probable route and possible alternative routes.

Floating Car Data

The term "Floating Car Data" (FCD) refers to data that is generated from a vehicle that is currently involved in traffic. This includes both the state of driving and the state of standing, e.g. B. in a traffic jam, in front of traffic lights or in a waiting area. A data record includes at least the time stamp and the current coordinates.

The use of the FCD process turns the vehicles into mobile sensors. Currently, taxi fleets are primarily used to generate FCD, as they already have the necessary equipment and headquarters for fleet management tasks.

Further developments of dynamic road maps

With these, a traffic sign recognition, z. B. vehicle speed regulating traffic signs, by means of an existing mobile camera and a transmission of the data to the operator or provider of the application enables. The users of the application receive an up-to-date road map with regard to the speed-regulating traffic signs, i. H. a dynamic road map that makes it possible to implement functions such as a roll-out assistant on correct data. Using traffic signs regulating the vehicle speed along the route as well as terrain elevation profiles, current vehicle speed and vehicle mass, etc., such a coast assist gives the driver recommendations to take off the accelerator in good time in order to coast to the next required speed and thus avoid braking maneuvers and save fuel.

• Geschwindigkeitsbegrenzungen, insbesondere Verkehrszeichen mit Geschwindigkeitsbeschränkungen,
• Aufhebung von Geschwindigkeitsbeschränkungen,
• Ortseinfahrten, die eine Geschwindigkeitsbegrenzung auf 50 km/h darstellen,
• Ortsausfahrten, die eine Aufhebung der Geschwindigkeitsbegrenzung auf 50 km/h darstellen,
• Kurvenkrümmungen und daraus abgeleitete relevante Kurvengeschwindigkeiten.

Information for the dynamic map includes:

• Speed limits, especially road signs with speed restrictions,
• Lifting of speed limits,
• Urban entrances that represent a speed limit of 50 km / h,
• Local exits that represent a lifting of the speed limit to 50 km / h,
• Curvatures and relevant curve speeds derived from them.

The road map can be stored electronically on a storage medium, for example on a server or in a cloud. The drivers of motor vehicles can at least temporarily be connected to the dynamic map on the server or in the cloud with their mobile devices via an application, for example the navigation system.

Navigation system with predictive road maps

The data content that can be made available to other components in the vehicle by a navigation system in the sense of a forecast depends on the map data available from the map supplier and can differ in scope and quality depending on the map supplier. It can be assumed that energy-relevant information, such as, in particular, height / gradient profiles, curvatures and speed profiles, is not available across the board. In particular, speed information and height or gradient information within Europe are essentially limited to high-ranking road classes. According to the roadmaps of the map suppliers, the comprehensive availability of height and gradient profiles, curvatures and speed information for high-ranking roads is planned. However, the availability of e.g. B. Incline information for residential streets not to be expected in the foreseeable future. However, there are approaches to use the vehicles with their sensors in order to obtain incline information derived therefrom directly or indirectly about the routes traveled, e.g. B. in the mentioned dynamic maps to save.

If a navigation system is available, but route planning is not carried out, both methods for adaptive route recognition of previously traveled routes and speculative methods are known.

Driver assistance systems (near horizon)

Driver assistance systems are increasingly using cameras and / or radar and / or ultrasonic sensors for environment recognition and situation and maneuver recognition up to a horizon of 500 m. In the context of predictive energy management in the near field, information on vehicles and / or obstacles in front is helpful To be able to convert acceleration energy. With knowledge of the deceleration distance as well as a speed and height profile, a load profile can be estimated and possibilities of regenerative and / or classic braking and / or sailing etc. can be implemented in an anticipatory and energy-optimized manner.

Ultimately, the near and far horizon help to estimate a load prediction and thus also a fuel consumption prediction over the route for the drive train or the vehicle and to continue to use the degrees of freedom in energy management.

Energy management and operational strategies

The more stringent requirements regarding CO ₂ reduction increase the need for hybrid drive concepts, electrification of auxiliary units, needs-based controls, switch-on and switch-off concepts, storage of excess thermal, electrical, mechanical energies and their transformations. Predictive methods are used for load prediction in order to fill or empty energy stores in good time, load distribution concepts are used to avoid local load peaks or overload.

These new possibilities for storage, transformation, decoupling / coupling and predictive control result in more degrees of freedom in the control and regulation of the power and energy flows in the vehicle. Handling and optimizing these is the task of energy management, including the associated offline and / or online optimization processes and algorithms. The boundary conditions of the operating strategies and optimizers are in most cases compliance with exhaust gas, drivability, service life, availability and comfort requirements.

Many hybrid operating strategies are based on minimizing the total energy consumption, consisting of the energy content of the fuel consumed and the electrical energy drawn from the traction battery. In order to simplify the optimization, an equivalence factor is used to convert fossil fuel to electrical energy or vice versa. It is therefore referred to as a so-called Equivalent Consumption Minimization Strategy (ECMS).

The internal combustion engine load profile can be estimated in the corresponding control unit based on vehicle and environmental parameters and the data contained in the EH. The EH provides information on speed limits, average speeds, inclines and bends along the route. This information can be used to create a speed profile. An algorithm for this is already in place. Approximate vehicle parameters, such as the vehicle mass, the rolling resistance coefficient, the flow resistance coefficient and the projected frontal area, are stored in the control unit. Approximate environmental parameters such as air density are also stored in the vehicle. With the driving resistance equation, the drive load for a fixed time grid, e.g. Every 100 ms, estimated in advance along the route.

Information about the road surface, such as asphalt, concrete, gravel, etc., can also be contained in the EH. This information can also be used to take into account the influence of the road surface on the rolling resistance coefficient.

To improve the load prediction, an explicit load profile can also be transmitted via the electronic horizon, which is created by the HP on the basis of past trips. For this purpose, the drive load is stored during each journey in a fixed time grid with a location reference, e.g. via GPS or coupling location. If a route has been driven several times, the drive load can be estimated based on the statistics of the previous journeys. To make changes along the route, e.g. B. speed limits, or driving behavior, e.g. B. faster travel on a known route, are taken into account in the statistics, only the last x trips to the route are used to estimate the drive load, with z. B. x = 10. A load profile generated in this way is driver- and vehicle-specific.

Driving and rest periods

Rest periods are times in which the driver can freely dispose of his time for a certain minimum period of time. Every driver must observe daily and weekly rest periods. Times of work or readiness for work as well as the time in the cabin spent in the moving vehicle are not idle times. The rest time can be spent in the vehicle, provided it is equipped with a sleeping cabin and is not moving.

The daily driving time in commercial goods or passenger traffic may not exceed 9 hours within a 24-hour period, but it may be extended to ten hours twice per calendar week.

The driving time may not exceed 4.5 hours without a break in driving. The driver must therefore take a break of at least 45 minutes after driving 4.5 hours at the latest. According to the legal definition, a break in driving is any period in which the driver is not allowed to drive or carry out any other work and which is used exclusively for recreation. In contrast to the daily rest period, the recovery phase can be completed as a passenger in the moving vehicle. Waiting times, e.g. when clearing the border or when loading or unloading the vehicle, count as a break in the journey if the expected duration is known in advance. The same applies to the times in the passenger seat or in the sleeping cabin in the moving vehicle as well as on ferry and train journeys.

Alternatively, the break in the journey may be split up by first inserting a 15-minute break and then a 30-minute break. It is important here that the total driving time, starting from the previous regular rest period, i.e. H. a break in driving, daily or weekly rest, up to the beginning of the 30-minute break in driving, does not exceed the required limit of 4.5 hours.

The regular daily rest period is at least 11 hours. If it lasts at least 9 but not 11 hours, it is a reduced daily rest period. The driver must take a daily rest period within each 24 hour period. The 24-hour period does not need to be the same as the calendar day. The daily rest period can be shortened three times between two weekly rest periods to 9 hours without having to make up for the shortened period. The full daily rest period can be taken in two parts, which is known as splitting, whereby the first part must comprise an uninterrupted period of at least 3 hours and the second part an uninterrupted period of at least 9 hours. Compliance with this order is binding. It should be noted that it makes no legally relevant difference where the driver stays, i.e. where he can can be shortened to 9 hours of rest if the driver spends the night at home, as well as if he spends the night in the vehicle during a tour.

The regular weekly rest period must be 45 consecutive hours after 6 x 24 hours or after the last weekly rest period. However, the weekly rest period of 45 hours can be reduced to 24 hours. Any shortening must be compensated for by a continuous rest period, which must be taken before the end of the third week following the week in question. When splitting the regular weekly rest period to at least 24 hours, however, the 21 hours that have to be made up must be taken into account, so that the missing weekly rest period of 21 hours is only recognized if this is attached directly to a rest period of at least nine hours. At least 30 hours of rest are required for recognition, unless the 21 hours to be made up are immediately preceded by a 45-hour regular weekly rest period before the end of the sixth daily driving time. A shortened weekly rest period must be compensated for at the latest before the end of the following third week following the shortened rest period, e.g. 66 hours of rest as a result of 45 hours and a missing 21 hours. In every double week there must be at least two weekly rest periods, at least one of which must be a regular weekly rest period ( 45 Hours). If a weekly rest period is within two weeks, you can choose for which of the two weeks the weekly rest period should apply.

In the context of the present invention, a rest time of a driver of the motor vehicle can be understood to mean a break in a journey of the motor vehicle that is longer than 15 minutes, preferably more than 30 minutes or 45 minutes, particularly preferably more than 5 hours.

Tachographs and tachographs

A tachograph, which is also known as a tachograph, trip recorder, trip counter or EC control device, is a tachometer with a connected measuring recorder that records driving and rest times, driving time interruptions, additional kilometers driven and the speed driven. The main task of the tachograph is to monitor driving and rest times. The digital tachograph already has personalized driver cards. This means that access to the vehicle is in principle only possible for authorized and trained drivers and / or a replacement for the normal key.

Driver monitoring and line of sight recognition, personalization

Methods for recognizing the direction of gaze of people by means of a camera are known. For this purpose, a so-called personalization, i. H. face recognition and teaching of the person's line of sight take place. Here z. B. first sought and recognized the typical facial features. Then the person to be trained has to fix a symbol or point on the display with your gaze, which is then shifted several times over the display surface.

Ultimately, this learning process must be carried out once for each person on the respective system or vehicle. When the system is in operation, it recognizes the specific person and, based on the personalized learning data, can assign the viewing direction to a precise millimeter position on the display.

A camera, for example an infrared camera, and a display or display are positioned in a defined manner with respect to one another. The system is geometrically calibrated at the end of the line at the OEM, e.g. by teaching-in with a chessboard. The cabin itself does not matter. Manufacturing tolerances are also compensated for. For each additional display in the vehicle, an additional camera is currently required in principle.

With the recognition of the viewing direction and associated position, e.g. B. on a display, so-called line of sight controls can be implemented. That is, wherever the driver is looking on the display, namely the direction of view as a pointer, this can be used to delegate the infotainment, such as the failure of call lists or cards, etc., for example. Confirmation inputs, e.g. via buttons or acoustic or interpretations of eyelid movements, are optionally possible.

Taking into account the mentioned boundary conditions, the presented method was developed, which allows a predictive determination of a necessary state of charge of the battery for emission and noise-free living or hotel operation and ensuring the restart of the internal combustion engine.

The predictive determination of a necessary state of charge of the battery before the residential or hotel operation and the restart of the internal combustion engine is based on known and / or predicted and / or learned driver or operator rest times and predicted personal consumption information of electrical consumers, taking into account consumption-relevant ambient or Environmental information and / or logistics or planning information carried out.

Based on this, predictive operating strategies of the energy management can then, so to speak, calculate back from the target SoC using the planned route and optimize the fuel consumption during the journey, which includes both controlling the generator or the electric machine for charging the battery and controlling and controlling the battery accordingly also to discharge the battery accordingly and in good time, in order to e.g. B. to be able to use recuperation potential.

The advantage lies in the consumption-optimized driving sales and at the same time emission-free and noise-free living or hotel operation and a safe restart of the combustion engine.

In a preferred embodiment of the method, a point in time and / or a duration of a future, in particular the next, rest period of the driver of the motor vehicle is determined in a first step. Here, regulations on driving and rest times and / or a current or current driving time of the driver and / or past driving and rest times of the driver and / or other drivers can be taken into account. Furthermore, the navigation or route planning of the motor vehicle and / or a current or forecast traffic and / or parking lot situation on a current route of the motor vehicle can be taken into account.

In a second step, the energy required for the break in the journey or rest time with the drive motor switched off for the operation of consumers connected to the vehicle electrical system, such as heating, air conditioning, coffee machine, etc., is determined. Vehicle data and / or consumer data, for example with regard to power consumption, can be taken into account here. Typical energy consumption in the case of past breaks in journeys or rest periods can also be taken into account. Furthermore, current or forecast weather and environmental conditions at the location of the break in the journey can also be taken into account.

In a third step, the setpoint value for the state of charge of the battery of the motor vehicle is determined for the future point in time. Vehicle data and / or consumer data, for example with regard to power consumption, can be taken into account here. The energy required for restarting or restarting the drive motor after the interruption in travel is preferably also taken into account. Current or forecast weather and environmental conditions at the location of the break in the journey can also be taken into account.

In a fourth step, a control strategy, in particular a charging strategy, for controlling the state of charge of the battery is determined in order to control the state of charge of the battery in such a way that the target value of the state of charge is reached at the future point in time. In this case, the battery can be charged at least at intervals while the motor vehicle is driving on a current route up to the location of the interruption in the journey. The control strategy can be determined taking into account a current state of charge of the battery and / or a state of health or state of health of the battery. The navigation or route planning of the motor vehicle and / or a speed and / or altitude profile on the current route and / or a current or predicted traffic situation on the current route of the motor vehicle are preferably taken into account. In addition, driving resistances or load profiles with regard to power and energy on the current route can also be taken into account. Furthermore, current or forecast weather and environmental conditions on the route can be taken into account when determining.

Finally, the method includes a step of controlling the state of charge of the battery of the motor vehicle based on the determined control strategy, in particular the charging strategy, on the route or route of the motor vehicle.

Typically, battery cell technologies are used that allow major changes to the battery SoC, e.g. lithium-ion batteries, without damaging the battery cells, e.g. B. sulfation in lead batteries, which reduce the capacity of the battery more and more.

It does not matter whether the electrical consumers for the residential or hotel operation from their own battery or via a converter from z. B. be fed by an electric traction battery. It is crucial that the electrical energy source is variable, ie the battery does not charge permanently, e.g. B. a generator with variable field excitation or mechanical shutdown. This degree of freedom of switching the load on the internal combustion engine enables a load point shift of the internal combustion engine and thus the possibility of optimizing consumption.

It is assumed that the times for the legally prescribed driving break of 45 minutes after a 4.5 hour drive at the latest or 15 minutes within the 4.5 hour drive and 30 minutes thereafter and the necessary electrical energy requirement during this time of the driving break are derived from the Battery can be covered including necessary restart of the internal combustion engine.

In this way, the minimum SoC, which is not to be undercut, can be specified for the battery for energy management or the operating strategy. This value can be determined through tests in the development or application phase or through a worst case analysis with regard to the operation of the electrical consumers during the interruptions in driving.

In further explanations it is a matter of determining the beginning, the duration and the energy requirement of the residential or hotel operation. In the following, the term residential operation is used for an overnight stay in the truck and the term hotel operation for overnight stays at the weekend.

Since the driving and rest times are regulated by law and digital tachographs are used together with personal driver cards, it is possible to estimate when and how long driving breaks and living or hotel operations can last. The digital tachographs measure and store tamper-proof daily driving times, weekly driving times, daily rest periods, weekly rest periods, breaks in driving, uninterrupted driving times, etc.

It should also be noted that trucks are increasingly being networked with planning and logistics systems. This means that the start and finish location as well as the start and finish times are known. In addition, the route is specified and the current position of the truck is known to the planning and logistics system.

Increasingly, the length of stay of the trucks at the logistics yards is being minimized, target times and arrival times are currently specified in advance and concepts for the automatic guidance of the truck or semitrailer or trailer etc. are being developed. As a result, the driver can leave the vehicle and comply with his statutory rest periods, such as the prescribed break in driving.

In the simplest case, the driver or a planning and logistics system for the route also plans the rest periods and interruptions in the journey in advance. This also includes whether the driver stays overnight or lives in the truck. As a result, all the marginal parameters for energy management or for the operating strategies are known, namely the route or route sections with the internal combustion engine running continuously and the target SoC of the battery. In principle, adaptive and speculative methods are known here.

Adaptive procedures

If the rest periods are not explicitly planned in advance, you can learn from the past, especially if the routes are always the same, e.g. Stuttgart - Hamburg - Stuttgart. When and where, statistically, at the earliest, on average, at the latest, the rest periods are used. Date, time, weather, person correlations etc. can also be taken into account.

Speculative proceedings

If no route planning is available, it can be speculated by means of routes previously driven which route will be taken and / or with knowledge of the statutory driving and rest times and the relevant current driver's cab, when they will be used at the latest and / or by adding or knowing the free rest areas along the assumed route, the location and time of the rest phases can be estimated.

The above-mentioned methods can also be used in combination, namely information from planning and logistics systems, navigation and traffic information, adaptive and speculative methods.

According to the legal requirements for daily rest time, e.g. 11 hours, or weekly rest time, e.g. B. 45 hours, including the possible variations and the current driver station in this regard, which are calculated or summed up and stored online in the digital tachograph, the beginning and the duration of the residential or hotel operation can be estimated. It is assumed that the electrical energy demand required during this time of the daily or weekly rest period can be covered by the battery, including the necessary restart of the internal combustion engine.

The minimum SoC of the battery, which is not to be undercut, can thus be specified for the energy management or the operating strategy. This value can be determined by tests in the development or application phase or by worst-case assumptions regarding the operation of the electrical consumers during the interruptions in driving. This includes storage in characteristic curves or characteristic diagrams or fixed values, parameters, etc. Optionally, a person-related and / or weather and / or environment-dependent energy consumption behavior can also be learned or estimated. Models and, if necessary, neural networks are used here.

All of the provisions explained above basically result in a forecast or prediction of the basic driving times, rest periods or driving breaks and living and hotel operating times over or on a planned or speculated route.

Based on the estimated necessary energy requirement in the rest periods or the SoC of the battery, the fuel consumption can be optimized in the preceding driving times or the preceding route using known methods or algorithms of energy management.

Illegal behavior with regard to driving and rest times is stored in the digital tachograph and can result in no optimum consumption being achieved and / or the internal combustion engine having to be started in the rest phases in order to supply the electrical consumers and charge the battery. If the prediction is incorrect, the fallback solution still remains a restart of the internal combustion engine and / or the maximum discharge of the battery is prevented, i. H. a minimally defined SoC is raised so that a safety reserve is kept.

On the one hand, a second slot or slot for the personal driver card is provided in the digital tachograph and, on the other hand, a plausibility check can also be made as to whether the second driver is on board, e.g. B. by means of the driver monitoring camera or other seat occupancy detection. In addition to the driver, other people present in the truck can be taken into account when estimating the energy consumption in the rest phases.

Noise-free or emotion-free zones can e.g. B. be noted in the navigation maps.

The route planning and localization can be implemented using a navigation device.

The connection to the logistics system is made, for example, with a Connected Control Unit (CCU), which usually requires the availability of a mobile service.

The operating strategy for fuel-optimized operation is calculated in the internal combustion engine control unit (ECU) and / or in the vehicle control unit (VCU).

The digital tachograph for monitoring driving and rest times and personalization is described above and is now mandatory.

All of the control devices mentioned are networked with one another via digital bus systems, such as CAN, Flexray, Ethernet, and thus enable the functions described here in a network.

Further advantages and embodiments of the invention emerge from the description and the accompanying drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or on their own, without departing from the scope of the present invention.

Figure list

• 1 shows in six graphs an operating strategy for an energy supply system of a truck.
• 2 shows a profile of the state of charge of a battery in an on-board network of a truck with an operating strategy according to the prior art.
• 3rd shows a profile of the state of charge of a battery in an on-board network of a truck in a further operating strategy according to the prior art.
• 4th shows a profile of the state of charge of a battery in an on-board network of a truck in a further operating strategy according to the presented method for controlling a state of charge of a battery of a motor vehicle.
• 5 shows a backward simulation in a flow diagram.

Embodiments of the invention

The invention is shown schematically on the basis of embodiments in the drawings and is described in detail below with reference to the drawings.

• täglich 45 min Parken mit ausgeschaltetem Motor (Kaffeepause),
• täglich Übernachtungshalt mit ausgeschaltetem Motor,
• Eingangssignale sind Drehzahl, Geschwindigkeit, Drehmoment.

1 shows an operating strategy in a driving cycle Stuttgart-Hamburg-Stuttgart with:

• daily 45 min parking with the engine switched off (coffee break),
• daily overnight stop with the engine switched off,
• Input signals are speed, speed, torque.

• normaler Antrieb: 500 W
• Parken bei Kaffeepause: 50 W
• Hotelübernachtung(täglich): 1h: 300 W, 3h: 100 W, Rest 50 W

The electrical consumption is:

• normal drive: 500 W
• Parking during coffee break: 50 W
• Hotel accommodation (daily): 1h: 300 W, 3h: 100 W, rest 50 W

A first graph 10 shows the course of the speed, a second graph 12th shows the course of the speed and a third graph 14th shows the course of the load. The courses are shown over the course of a week. This also includes Saturday 16 and the sunday 18th to recognize.

A fourth graph 20th shows the course of the speed, a fifth graph 22nd shows the course of the speed and a sixth graph 24 shows the course of the load. These graphs 20th , 22nd , 24 show the gradients on a Monday morning. There is also a coffee break here 26th to recognize.

2 shows a prior art operating strategy. A graph 50 , on its abscissa 52 the time and on its ordinate 54 the state of charge is plotted, shows the progression of the state of charge 56 . Travel times alternate 60 and overnight stays 62 from. On the weekend 64 then the state of charge falls from a point in time 66 strong. During the overnight stays 62 there is a discharge of the battery by supplying consumers, such as TV, radio, etc.

The operating strategy provides for the battery to be used while driving 60 load constantly. However, this is disadvantageous for the consumption of fuel. After driving on a Friday at the time shown 66 97.5% and thus almost the entire capacity of the battery are available for hotel operation.

3rd Figure 12 shows another prior art operating strategy. A graph 150 , on its abscissa 152 the time and on its ordinate 154 the state of charge is plotted, shows the progression of the state of charge 156 . Travel times alternate 160 and overnight stays 162 from. On the weekend 164 then the state of charge falls from a point in time 166 strong.

The operating strategy shows an improved procedure compared to the strategy 2 . Among other things, sailing operation and recuperation with active battery discharge are provided. The fuel consumption efficiency is good. After driving on a Friday at the time shown 166 85% and thus significantly less capacity are available for hotel operations.

The illustration also shows that trucks in regular long-distance traffic on the same routes at the same times or days have a reproducible load profile, in particular with regard to engine speed, vehicle speed and engine power.

4th shows in a first graph 200 the state of charge of the on-board power supply battery with a charging strategy that determines the state of charge 201 always keeps close to the maximum charge level.

This charging strategy has the advantage that after the internal combustion engine and thus the generator have been switched off, e.g. for overnight stays or at the weekend, sufficient electrical energy is always available to supply the electrical consumers and to start the internal combustion engine.

On the right shows a second graph 202 the state of charge 203 the on-board power supply battery with a preferred charging strategy.

The generator for charging the battery is driven by the combustion engine like other ancillary units and consumes a proportion of fuel depending on the generator load. The following table 1 gives an overview of possible loads: Table 1: Overview of the loads Loads energy tension electricity Outside lighting [W] [V] [A] Parking light 74 24.7 3.0 Hazard lights 20th 24 0.8 Lighting trailer 50 24.7 2.0 Lighting interior Instrument lighting 5 24.7 0.2 Rear work light 66 24.7 2.7 Reading lamps (8 pcs.) 20th 24.7 0.8 Interior lighting red 20th 24.7 0.8 White interior lighting 20th 24.7 0.8 Infotainment / instruments Instrument cluster 3rd 23.9 0.1 radio 100 28.3 3.5 Tachograph 10 28.3 0.4 Air conditioning / heating Ventilation, full level 299 28.3 10.6 Ventilation, half level 68 28.3 2.4 Stand heating 129 28.3 4.6 fridge 38 28.3 1.3

• Parken bei Kaffeepause: 50 W
• Hotelbetrieb: 1h: 300 W, 3h: 100 W, Rest 50 W

The sum of the possible loads or consumption for a hotel is 300 to 900 W. Defined load profiles for the simulations carried out are:

• Parking during coffee break: 50 W
• Hotel operation: 1h: 300 W, 3h: 100 W, rest 50 W

It has now been shown that the charging strategy according to the first graph 200 disadvantageous compared to the charging strategy according to the second graph 202 is. This is due to the unused possibility of being able to operate the internal combustion engine more at optimum operating points thanks to a variable generator load. The consequence, however, is a significantly fluctuating state of charge of the battery. However, it should be ensured that sufficient energy is available for idle phases and that the internal combustion engine can be started reliably after these idle phases.

5 shows a basic backward simulation in a flow diagram. A cycle can be seen 300 (Route with gradient, coefficient of friction, ambient air pressure, wind, speed, deceleration and acceleration, etc.), a motor vehicle 302 with mass, cross-sectional area, drag coefficient, wheel friction, wheel circumference, etc., a gear 304 with gear ratios, efficiency, an electric drive 306 with operating map and degrees of efficiency, one clutch 308 , an internal combustion engine or drive motor 310 with operating map and efficiency, a fuel tank 312 with SoC, an electric traction storage device or a battery 314 with SoC and all electrical consumers 316 .

All mechanically driven consumers or ancillary units, e.g. B. on the belt drive of the internal combustion engine such as water pump, air conditioning compressor, generator, etc., which, depending on the question, could be included in the efficiency of the internal combustion engine.

A P2 hybrid system architecture is shown, the electric motor and combustion engine are on the same drive shaft and have the same speed. The operating strategy, which portion of the necessary torque comes from the internal combustion engine and / or electric motor, is not shown.

In a conventional drive system today, the components would 306 , 316 , 314 not applicable, as is the case with truck examinations or simulations. Here, however, sailing and recuperation and deeper discharging and overcharging of the battery than is common today, i.e. not permanent charging as is common today, were also permitted. There is sailing with a combustion engine, coupling and uncoupling and also sailing with a combustion engine, coupling and uncoupling. The former was examined in a truck investigation or simulation. During operation, the generator can also be activated by disengaging or varying the field excitation in the load and thus charging the battery 314 can be varied. The latter was examined in the truck simulation. Will the battery 314 not charged or insufficiently charged, it is due to the electrical consumers 316 unload.

In operating states such as thrust, deceleration or braking, recuperation means letting the generator generate maximum energy and in the battery 314 to save provided the battery 314 is not full.

This basic recalculation shown is required for a load estimate over a planned route, i.e. based on the driving resistances over the planned route via vehicle or wheel into the drive system with the ancillary units (recalculation).

The electrical generator for the vehicle electrical system is not shown. This is on the internal combustion engine belt drive (auxiliary unit).

In a high-voltage hybrid system, they would be electrical consumers 316 or high-voltage consumers are wholly or partially supplied from the traction storage system for parking or living and the internal combustion engine is started from a separate starter battery (not shown) and electric starter (not shown), the SoC estimates for both batteries would have to be estimated separately .

Claims (11)

Method for controlling a state of charge (201, 203) of a battery (314) of a motor vehicle (302), the motor vehicle (302) having a drive motor (310) and an on-board network with the battery (314) which can be charged by means of the drive motor (310), wherein a target value for a future point in time is determined for the state of charge (201, 203), taking into account at least one first boundary condition, the state of charge (201, 203) of the battery (314) a predetermined operation of the motor vehicle (302) when switched off Drive motor (310) enables, and the state of charge (201, 203) of the battery (314) is controlled taking into account at least one second boundary condition in such a way that this target value is reached at the future point in time, so that predictive energy management in the electrical system of the motor vehicle (302) is carried out. Procedure according to Claim 1 , at which the future point in time is the point in time at which the drive motor (310) is switched off, whereby the beginning of a rest period for a driver of the motor vehicle (302) is initiated. Procedure according to Claim 1 or 2 , in which the specified operation of the motor vehicle (302) with the drive motor (310) switched off ensures that loads of the motor vehicle (302) are adequately supplied from the at least one battery (314) during a rest phase of the drive motor (310) and that the drive motor is reliably started ( 310) after the resting phase. Method according to one of the preceding claims, in which an internal combustion engine, a hybrid drive and / or an electric motor is used as the drive motor (310). Method according to one of the preceding claims, in which the first and / or second boundary condition taken into account is selected from one of the following boundary conditions: time and / or duration of rest and driving times of a driver of the motor vehicle (302), route planning of the motor vehicle to the location of a break in the journey of the motor vehicle, traffic and / or weather situation on a current route and / or at the place where the motor vehicle is interrupted, energy requirements of consumers connected to the vehicle's electrical system when the journey is interrupted, speed and / or altitude profile and / or driving resistances on the current route, Data from the electronic horizon of the motor vehicle, floating car data, data from a dynamic road map, data from a driver assistance system, data from energy management of the motor vehicle, data from a tachograph and / or tachograph of the motor vehicle, data from a driver monitoring system of the motor vehicle. Method according to one of the preceding claims, in which a SoH (state of health) of the at least one battery (314) is taken into account when determining the state of charge (201, 203). Method according to one of the preceding claims, in which a recuperation potential of the at least one battery (314) is taken into account when determining the state of charge (201, 203). Method according to one of the preceding claims, which is carried out in an on-board network of a truck. An arrangement comprising in particular a control unit which is set up a method for controlling a state of charge (201, 203) of a battery (314) of a motor vehicle (302) according to one of the Claims 1 to 9 execute and / or control. Computer program that is set up, the method according to one of the Claims 1 to 8th to control. Machine-readable storage medium on which the computer program is based Claim 10 is stored.

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