Method for determining an operating profile for comfortable operation of vehicle consumers as well as battery monitoring device and motor vehicle

Abstract

Method for determining an operating profile (8) for the comfort operation of vehicle consumers (4), comprising the following steps: - Determining an available energy content (6) of a vehicle battery (2) for comfort operation as a function of predetermined battery characteristics (5), comprising at least: an internal resistance value (Ri) from a measured ripple current, a temperature value (5a), a predetermined battery characteristic curve (5b), and a current discharge current (I) of the vehicle battery (2), characterized by the following steps: - Determining a desired operating time (7) of the comfort operation of the vehicle consumers (4), - Defining the operating profile (8) for the comfort operation of the vehicle consumers (4) within the operating time (7) as a function of the available energy content (6) and a predetermined consumption value of the vehicle consumers (4),wherein, to determine the available energy content (6) for comfort operation, a total energy content of the vehicle battery (2) and a minimum energy content for an emergency pulse are determined from the battery characteristics (5), and the available energy content (6) is determined from a difference between the total energy content and the minimum energy content, such that the minimum energy content remains in the vehicle battery.

Description

The invention relates to a method for determining an operating profile for comfort operation of vehicle consumers. The invention also relates to a battery monitoring device for a vehicle battery of a motor vehicle and to a motor vehicle having a corresponding battery monitoring device and a vehicle battery.Motor vehicles are known in which a diagnosis of the vehicle battery for a shutdown phase of the motor vehicle is used to determine whether or not a cold start is possible under the current boundary conditions, such as a temperature and a state of charge of the vehicle battery, and the requirements imposed on the vehicle battery by a vehicle drive, such as an internal combustion engine or an electric motor ("remain"). The diagnosis as a result delivers the charge or energy to the patient, which can be drawn from the vehicle battery. In order to avoid a standstill during a cold start, an energy reserve can be determined and retained.As a result of the advanced electrification of system components in modern motor vehicles, such as vehicle consumers, for example, the demands made of the vehicle battery have meanwhile increased. It has been shown, for example, that ensuring an electrical energy supply of consumers for vehicle control, such as a brake and steering, for a minimum period of time, in particular a stopping process for an emergency stop, places higher demands on a voltage stability or a voltage level of the vehicle battery than ensuring the cold start, for example. The energy reserve for the cold start, which is ascertained with the above-described diagnosis, is therefore no longer sufficient to ensure the requirements for driving dynamics for an emergency stop.As a result, vehicle consumers who perform a comfort function, such as an infotainment system, are switched off or deactivated too late with the diagnosis implemented hitherto from the viewpoint of ensuring the energy reserve for the driving dynamics. A deep discharge of the vehicle battery can thus occur. The energy reserve for the emergency stop can no longer be ensured.The diagnostic function known up to now has therefore been developed further in order to ensure an energy reserve for the driving dynamics. This energy reserve for the driving dynamics, i.e., for example, for safety functions that the motor vehicle must be able to perform for a regulation participation in road traffic, is also referred to below as an emergency pulse.For example, DE 10 2020 127 696 A1 discloses a method for determining an available energy amount of a vehicle battery for such an emergency pulse. In this case, an internal resistance value for the vehicle battery is determined from on-board electrical system faults occurring in an on-board electrical system of the motor vehicle, the so-called ripple current. Together with a known temperature value, a battery characteristic curve and a current discharge current of the vehicle battery, it is then possible to draw conclusions as to the amount of energy available.The use of ripple current for determining a battery impedance is known, for example, from DE 103 37 064 A1. In this case, parameters of a model of a battery impedance are carried out by evaluating alternating components of a battery current and a battery voltage. A prediction of a high-current load capacity of a vehicle battery, in particular of a starter battery for a motor vehicle, can thus be determined.Furthermore, DE 10 2017 221 248 A1 discloses a method for determining a current state of charge value of a battery. In this case, a characteristic curve field is provided which indicates an internal resistance for the specific battery type for respective different predetermined temperature ranges as a function of the state of charge for the specific battery type.DE 10 2019 204 959 A1 discloses a method in which an energy management module makes suggestions to a driver for setting operating parameters for a vehicle, specifically as a function of a desired destination and the energy requirement determined. For example, various predetermined comfort modes are proposed to the driver and a maximum possible range of the electric vehicle in the respective comfort mode is displayed. The comfort modes differ by the type and number of the comfort systems switched on / off and their operating parameters.DE 10 2014 216 150 A1 discloses an onboard display device which determines and displays a remaining driving distance which represents an estimated value of how far a vehicle can still drive with the remaining electrical energy in the battery.DE 10 2020 130 858 A1, for example, discloses a method in which an energy saving mode for comfort functions in the vehicle is proposed and activated as a function of an amount of energy in an energy store for a vehicle. In this case, for example, the function of a head-up display or of a mobile wireless charging device can be reduced or switched off.The energy stored in the vehicle battery or excess energy above the safety margin for the emergency pulse can be used, for example, to operate the vehicle consumers in a comfort mode. In the comfort mode, for example, a comfort function can be implemented, for example, for entertainment or assistance of an occupant of the motor vehicle.In order not to rely on the emergency pulse and to remain in position during the travel with the motor vehicle, for example, it may be advantageous to know an energy content of the vehicle battery for comfort operation and to select a corresponding operating profile for comfort operation of the vehicle consumers.It is the object of the present invention to provide a possibility for determining an operating profile for comfort operation of vehicle consumers in order to avoid the motor vehicle from being kept in a standstill.The object is achieved by the subject matters of the independent claims. Advantageous refinements of the invention are disclosed by the dependent patent claims, the description and the figures.The invention is based on the realization that an available energy content of the vehicle battery for comfort operation can be calculated from the same battery characteristics as the energy content for an emergency pulse. From the ascertained energy content for comfort operation, an operating mode for the vehicle consumers can then be determined in order to avoid the use of the emergency pulse.Accordingly, in one aspect, the invention relates to a method for determining or selecting an operating profile for comfort operation of vehicle consumers. By operating with the respective operating profile, for example, a comfort function can be carried out with the respective vehicle consumer in comfort operation. For this purpose, the method comprises the steps described in more detail below.First, an available energy content of a vehicle battery for convenience operation is determined. The determination is carried out as a function of predefined battery characteristic data, which at least comprise: an internal resistance value from a measured ripple current, a temperature value, a predefined battery characteristic curve and a current discharge current of the vehicle battery. A desired useful life of the comfort operation of the vehicle consumers is then determined. An operating profile for the comfort operation of the vehicle consumers within the useful life is then defined as a function of the available energy content and a predetermined consumption value of the vehicle consumers.In other words, power availability, i.e., for example, a charge content of the vehicle battery over a remaining travel time of the vehicle, may be taken into account for performing a comfort function. As a result, for example, adjustability or usability of the vehicle consumers for comfort operation can be set, in particular, for example, restricted, by defining the operating profile.This results in the advantage that the available charge of the vehicle battery above the safety margin, i.e. for example of the aforementioned emergency pulse, can be selected optimally for the useful life or useful time. In particular, it can be avoided in that the safety reserve has to be used during the useful life and the motor vehicle then remains in a standstill, for example.The determination of an available energy content or an energy amount of a vehicle battery for a predetermined vehicle function, such as the emergency pulse, as a function of the battery characteristics mentioned in the present method, is known per se from the prior art, in particular from the above-mentioned DE 10 2020 127 696 A1. In comparison with the prior art, in which the energy content for the emergency pulse is determined, for example, a different battery characteristic curve or a battery characteristic curve with a different value range can be used for determining the comfort operation. This makes it possible to take into account that other requirements are placed on a current intensity and on a voltage limit to be maintained for the comfort operation than for an emergency pulse.The battery characteristic curve can be determined, for example, from requirements and / or specifications of the vehicle battery, in particular from a design of the vehicle battery for comfort operation. The battery characteristic curve can preferably be determined by means of one or more measurements and thus provide a good estimate of the current energy content. The battery characteristic curve can be present or stored in a data memory, for example. The battery characteristic curve can be provided in particular as a look-up table or a function of the energy content as a function of the battery characteristic data, in particular the internal resistance value. The battery characteristic curve can preferably be provided as a function of a manufacturer, a rated capacity of a battery technology and / or a service life of the vehicle battery, as is known from the prior art.The battery characteristic curve can be, for example, a current-voltage characteristic curve or an SOC characteristic curve (SOC: State of Charge) or a capacity characteristic curve. Alternatively or additionally, the battery characteristic curve can be determined or predefined, for example, as a function of an Arrhenius equation and / or the Peukert equation.The calculation or determination of the internal resistance value from the measured ripple current is known from the prior art, in particular from the above-mentioned DE 103 37 064 A1. In this case, it is important that only a higher-frequency excitation, i.e. an AC part (AC: alternating current) or alternating component of the battery current and the voltage response resulting therefrom, is evaluated or taken into account in order to calculate the internal resistance of the vehicle battery. A DC component (direct current) or DC component is not used for the resistance evaluation. The internal resistance value may be a numerical value of the internal resistance of the vehicle battery, which may be indicated by the physical unit "ohm", for example.In order to allow the constancy or instability of the available energy content, which is present on account of the electrochemistry of a vehicle battery, to be incorporated, the temperature and the currently flowing discharge current are also taken into account. The temperature value can be determined or measured, for example, by means of a temperature sensor. The current discharge current can be determined or measured, for example, by means of a current sensor.In the present case, the discharge current refers in particular to a discharge current intensity. Its value may depend, for example, on a number and a current operating state of the respective vehicle consumers. The operating state specifies in particular a current consumption value of the vehicle consumers, that is to say for example a power or energy requirement which the respective vehicle consumer currently requires for operation. The respective operating state or operating mode can be predefined or stored in the operating profile.Preferably, a compensated internal resistance value can be calculated from the battery characteristics. For this purpose, for example, the internal resistance value from the ripple current can be calculated with respective correction values assigned to the remaining battery characteristics.The available energy content in the present case means a current and / or a voltage and / or a power of the vehicle battery, which is or can actually be freely available from the vehicle battery for carrying out comfort operation and can be removed, in particular within the useful life. The energy content can thus indicate, for example, the amount of electrical charge still available or usable per unit time. The energy content may also be referred to as charge content. The energy content or the charge content can preferably be a numerical value with the physical unit amp-hours "Ah".The energy content can correspond, for example, to an amount of energy or be a variable assigned to the amount of energy. The amount of energy may indicate, for example, the amount of current needed or desired per time. The amount of energy can thus describe, for example, the energy requirement of one of the vehicle consumers, while the energy content describes the energy that can actually be made available by the vehicle battery.The useful life may be a time period or time interval that indicates how long the vehicle consumers or at least one of the respective vehicle consumers should be operated in the comfort mode. The useful life can be present, for example, as an estimated value. In this case, the useful life can be determined or estimated, for example, from a known operating behavior of the vehicle consumers. Alternatively, the usage time may correspond to a remaining travel time, for example. The useful life can be determined from navigation data, for example.In the present case, a vehicle consumer means in particular an electrical consumer or an electrically operated component. This can form an electrical load for the vehicle battery. That is, the vehicle load may be connected to the vehicle battery for the respective operation. The electrical energy supply is thus effected by means of the vehicle battery.For example, a vehicle consumer may perform various functions. In the present case, a distinction is made in particular between a safety function and a comfort function. A vehicle consumer which is designed to carry out a safety function can be referred to as a safety-relevant consumer or safety consumer. This means that it is a component which is absolutely necessary for traffic-regulation or traffic-permitted operation of the motor vehicle. A corresponding consumer can be, for example, a brake or a steering system or a crash sensor system of the motor vehicle.To perform the safety function, the associated vehicle consumer can be operated in a safety mode. The safety operation can comprise, for example, the aforementioned emergency pulse.A vehicle consumer which is designed to carry out a comfort function can be referred to as comfort consumer or non-safety-relevant consumer. This means that it is a component which is provided in particular only for driving comfort, that is to say for example for entertainment and / or assistance of an occupant of the vehicle. Such consumers therefore do not fulfil any safety-relevant functions as have been described above. A corresponding consumer can be, for example, a telephone system, an air conditioning system, a radio, an infotainment system or a so-called parking assistant of the motor vehicle.To perform the comfort function, the associated vehicle consumer can be operated, for example, in the comfort mode mentioned at the beginning. This differs in particular from the aforementioned safety operation. For example, lower requirements for a current intensity or a load resistance or a voltage level can be predefined for the comfort operation than for the safety operation.The predetermined consumption value can be understood in the present case as a value which indicates the consumption, that is to say for example an energy or power demand, for the respective vehicle consumer preferably within the useful life. The consumption value can be present, for example, as a current or voltage value or power value. The consumption value may comprise, for example, the current discharge current or an average discharge current per time extrapolated to the useful life. The consumption value can be measured, for example, with a corresponding sensor, such as a current or voltage sensor, or can be taken from a predefined characteristic curve.The operating profile means a characteristic map which specifies what consumption the vehicle consumer or consumers may have within the useful life. For this purpose, the operating profile can comprise, for example, a respective operating value and / or a respective operating setting for at least one vehicle consumer. An operating value can be, for example, a maximum power, an operating duration or an on or off time for the respective consumer. By setting or converting the respective operating setting, the respective vehicle consumer can be placed in the aforementioned operating state.The invention also includes embodiments which provide additional advantages.According to an embodiment, the operating profile is selected from one of several categories depending on the available energy content. This means that there can be at least two different categories of operating profiles with, for example, respectively different operating values from one another. Depending on how much energy is still available in the vehicle battery for comfort operation, one of the categories can be selected. Depending on the category, different settings can thus result for the respective vehicle consumer.According to a further embodiment, it is checked in this context whether the available energy content falls below a minimum limit value of a maximum energy content of the vehicle battery predefined for comfort operation. Only if a result of the check is positive is an operating profile of a first category selected according to which at least one of the vehicle consumers is deactivated.Particularly preferably, for example, all vehicle consumers that are provided for comfort operation are deactivated. Thus, if no or only slight energy is available for comfort operation, the respective vehicle consumer or consumers can be deactivated. In the case of an operating profile of the first category, comfort operation of the vehicle consumers is therefore preferably no longer permissible. For this purpose, the operability of the consumers and the operation of the consumers can be switched off, for example.In the present case, the maximum energy content means an energy content which the vehicle battery can make maximum available for comfort operation in the completely fully charged state. The minimum limit value is, in particular, a lower limit or an availability limit of the maximum energy content. The minimum limit value can thus indicate, for example, a limit value, at the instance of which the emergency pulse is necessary for operating the safety consumers to fall below.A prioritization may be predefined for the deactivation of the vehicle consumers. For example, the prioritization may be based on consumption values of the vehicle consumers. The higher the consumption, the earlier or rather the respective vehicle consumer can be deactivated, for example.According to a further specific embodiment, it is checked whether the available energy content is in a predefined lower sub-range of the maximum energy content of the vehicle battery predefined for comfort operation. Only if a result of the check is positive is an operating profile of a second category selected, which comprises a reduced consumption value of the vehicle consumers compared to at least one third category. In comparison with the third category, in the second category the consumption of the vehicle consumers over the useful life is thus reduced.In other words, the second category may include provision for restricted operation or restricted operability of the consumers by an operator or an occupant. The operating values, i.e. for example settings for the consumers, can therefore only be set or selected to a limited extent.In the case of a low energy content, i.e. in the lower sub-region, a particularly severe operating profile can thus be selected, for example. For example, voltage dips due to high loads can be avoided.In comparison, for the operating profile, for example, the third category may be selected if the result of the check is negative.This is the case, for example, when the available energy content is greater than the lower sub-range, i.e. the energy content lies, for example, in a predefined upper sub-range of the maximum energy content. In the third category, correspondingly higher consumption values are permitted. Preferably, a consumption value for the vehicle consumers in the third category is unrestricted. That is, the operating values or settings for the respective vehicle consumer can be freely selected or freely set. Unlimited operation and unlimited operability of the vehicle consumers is possible.The aforementioned operating profile categories can thus be differentiated, for example, according to consumption values over the useful life. A consumption value of 0 can be provided for the first category. A smaller consumption value can be provided for the second category than for the third category.The lower portion may be bounded at one end by the minimum limit value, for example. As an upper limit, the lower sub-range may include, for example, a predetermined maximum limit value. The maximum limit value can be, for example, about 50 percent of the maximum energy content, in particular about 30 percent of the maximum energy content, preferably about 15 percent of the maximum energy content, particularly preferably about 10 percent of the maximum energy content.According to the invention, in order to determine the available energy content for comfort operation, a total energy content and a minimum energy content for an emergency pulse are determined on the one hand from the battery characteristics. The available energy content for comfort operation is then determined or calculated from a difference of the total energy content and the minimum energy content.The total energy content is to be understood in the present case as energy content which the vehicle battery can currently make available overall. The total energy content thus comprises both the energy content for the emergency pulse, i.e. the minimum energy content, and the energy content for comfort operation. This type of calculation can ensure, in particular, that the minimum energy content, i.e., the safety margin for the emergency pulse, always remains present in the vehicle battery.For use cases or application situations which can arise in the method and which are not explicitly described here, provision can be made for an error message and / or a request for inputting a user feedback to be output and / or for a default setting and / or a predetermined initial state to be set according to the method.According to a further aspect, the invention also relates to a battery monitoring device for a vehicle battery. The battery monitoring device is configured to carry out or execute a method as described above. The battery monitoring device can preferably be implemented as a control device or computing device for the motor vehicle. The control device can have, for example, a data processing device or a processor device which is configured to carry out an embodiment of the method according to the invention. For this purpose, the processor device can have at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (field programmable gate array) and / or at least one DSP (digital signal processor).Furthermore, the processor device can have program code which is configured to carry out the embodiment of the method according to the invention when executed by the processor device. The program code can be provided as binary code or assembler and / or as source code of a programming language (e.g. C).The program code can be stored in a data memory of the processor device. The data memory can be configured, for example, at least partially as a nonvolatile data memory (for example as a flash memory and / or as an SSD-solid state drive) and / or at least partially as a volatile data memory (for example as a RAM-random access memory).Furthermore, according to a further aspect, the invention also relates to a motor vehicle having a vehicle battery and a battery monitoring device as has been described above. The battery may be, for example, a starter battery and / or a traction battery of the motor vehicle. In particular, the vehicle battery can comprise at least one lead storage battery and / or a lithium-ion storage battery. The motor vehicle is preferably designed as a motor vehicle, in particular as a passenger car or truck or as a passenger bus or motorcycle.The invention also includes developments of the battery monitoring device according to the invention and of the motor vehicle according to the invention, which have features as have already been described in connection with the developments of the method according to the invention. For this reason, the corresponding developments of the battery monitoring device according to the invention and of the motor vehicle according to the invention are not described again here.The invention also includes the combinations of the features of the described embodiments. The invention therefore also comprises implementations which each have a combination of the features of a plurality of the described embodiments, provided that the embodiments have not been described as mutually exclusive.Exemplary embodiments of the invention are described below. The following shows: FIG. 1 shows a schematic illustration of a motor vehicle having a vehicle battery and a battery monitoring device for presetting an operating profile for comfort operation of vehicle consumers; and FIG. 2 shows a schematic method flow diagram for a method for presetting the operating profile for the comfort operation of the vehicle consumers.The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another and that also develop the invention independently of one another. Therefore, the disclosure is intended to include combinations of the features of the embodiments other than those illustrated. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.In the figures, identical reference numerals designate functionally identical elements.FIG. 1 shows a motor vehicle 1 having a vehicle battery 2 and a battery monitoring device 3.In FIG. 1, the motor vehicle 1 is designed as a passenger car by way of example. The vehicle battery 2 may be, for example, a traction battery of the motor vehicle 1. The battery monitoring device 3 can be, for example, a control unit with at least one microcontroller. For example, the battery monitoring device 3 can be designed as an ECU (electronic control unit) or central on-board computer of the motor vehicle 1.According to FIG. 1, motor vehicle 1 includes, for example, three vehicle consumers 4 that can be operated or can be operated in comfort operation. The vehicle consumers 4 are in the present case, for example, a radio 4 a, an air conditioning system 4 band an update module 4 c. The update module 4 cmay be used, for example, to update motor vehicle software.For operation in the comfort mode, electrical energy can be provided from the vehicle battery 2 to the vehicle consumers 4. For this purpose, the vehicle consumers 4 can be connected to the vehicle battery 2 by means of an on-board power supply system, for example. The on-board power supply system is not shown in FIG. 1 for the sake of clarity.The vehicle consumers 4 illustrated in FIG. 1 can also be referred to as comfort consumers. That is, the vehicle consumers 4 may implement a comfort function for an occupant, such as a driver of the motor vehicle 1. A comfort function may include, for example, entertainment or assistance of the occupant. In particular, a comfort function is to be understood as a function that is not relevant to safety, i.e. is not necessary for traffic-permitted operation of the motor vehicle in road traffic.Thus, the comfort consumers shown in FIG. 1 are to be distinguished from so-called safety consumers. In contrast to the comfort consumers, the safety consumers can be vehicle consumers that execute a safety function for the motor vehicle 1. These may be safety-relevant consumers which are absolutely necessary in order to enable traffic-permitted operation of the motor vehicle 1 in road traffic. These include, for example, a brake and / or a steering system of the motor vehicle.In order to be able to carry out a safety operation, i.e. an operation of the vehicle consumers which can fulfil a safety function, a safety reserve of electrical energy must be kept available at all times in the vehicle battery 2. This safety margin may be an energy content of the vehicle battery 2 that is necessary to carry out a so-called emergency pulse. With the emergency pulse, it is possible to safely stop the motor vehicle 1 while complying with predefined traffic rules. This means that, with the safety reserve, for example, a brake and steering system must be able to be operated unrestrictedly for carrying out a stopping process until the motor vehicle 1 is at a safe standstill. The available energy content for the emergency pulse is also referred to below as minimum energy content.This safety margin must not be used for the comfort operation of the vehicle consumers 4, in particular. For operating the comfort consumers 4, an available energy content for the comfort operation can instead be stored in the vehicle battery 2. This available energy content 6 is also referred to below as comfort energy.In the present case, an energy content means in particular a charge content or a charge amount of the vehicle battery 2, which can actually be made available or tapped by the vehicle battery 2 for the respective operation (safety operation or comfort operation).The energy content 6 for the comfort operation and the energy content for the safety operation can together form a total energy content of the vehicle battery 2. This means the total electrical energy which is stored and retrievable in the vehicle battery 2.In order to prevent the motor vehicle 1 from remaining in a standstill during a useful period 7 of comfort operation, i.e. for example during a journey with the motor vehicle 1, the battery monitoring device 3 is now used to monitor the energy content of the vehicle battery 2. In addition, a suitable operating profile 8 for the vehicle consumers 4 in the comfort mode can be selected with the battery monitoring device 3 for the useful life 7.FIG. 2 shows a schematic representation of a method flow diagram with individual method steps, which describe the setting or presetting of the operating profile 8 by way of example.The method is started with a step S 1. In step S 1, the available energy content 6 of the vehicle battery 2 for comfort operation is determined or determined as a function of predefined battery characteristics 5. The battery characteristic data 5 comprise at least one internal resistance value Ri, which is determined from a so-called ripple current of the vehicle battery 2. Furthermore, the battery characteristic data 5 in the present case comprise a temperature value 5 a, a predefined battery characteristic curve 5 band a current discharge current I of the vehicle battery 2.The use of the described battery characteristic data 5 for calculating an energy content for the emergency pulse is known per se from the prior art. The battery characteristics 5 can, however, also be used to determine the total energy content and the available energy content 6 for comfort operation. In this case, the energy content 6 can be calculated, for example, from a difference between the total energy content and the minimum energy content for the emergency pulse. How the calculation can be carried out specifically is described in more detail later.After the energy content 6 is known for comfort operation, the method can continue in a step S 2. In step S 2, a desired useful life of the comfort operation of the vehicle consumers 4 is determined. The useful life can be calculated, for example, from a remaining travel time of the motor vehicle. The travel time can be, for example, an estimated value which can be estimated as a function of known travel distances traveled by the motor vehicle 1. Alternatively, the travel time can be known, for example, from navigation data of a navigation device.The method is then continued in a step S 3. In step S 3, the operating profile 8 for the comfort operation of the vehicle consumers 4 within the useful life 6 is defined as a function of the available energy content 6 and a predetermined consumption value of the vehicle consumers 4. For this purpose, one of several categories can be selected for the operating profile 8. In the present exemplary embodiment, the selection can be made, for example, from three different categories.Different operating values or operating settings may be provided for the vehicle consumers for each category. This means that by selecting the respective operating profile category, the respective vehicle consumer 4 can be charged with operating values assigned to the category. An operating value can be, for example, a power or an operating duration and / or an on or off time of the respective vehicle consumer 4. As a result, it can be predefined with the selected category, for example, how long or how often or with what power the respective vehicle consumer can still be operated over the remaining useful life in the comfort mode. Thus, a maximum consumption, which indicates an energy or power requirement of the respective vehicle consumer 4, can be predefined.In order to select the appropriate category, the respective consumption value of the vehicle consumers 4 within the useful life 7 is also taken into account. That is, it can be checked or estimated how high the consumption of the vehicle consumers 4 is or within the useful life 7 will be expected if the corresponding operating profile 8 is selected. This makes it possible to ensure that the energy content 6 for comfort operation is sufficient to meet the demand for electrical energy of the vehicle consumers 4 for comfort operation for the remaining useful life 7.In step S 3, it can be checked, for example, to select the category of the operating profile 8, whether the ascertained energy content 6 is in a lower sub-range of a maximum energy content of the vehicle battery 2 predefined for comfort operation or falls below a minimum limit value of the maximum energy content. The maximum energy content is a maximum energy that the vehicle battery 2 may include or have. The minimum limit value may be a lower limit which specifies the transition from the comfort mode to the safety margin, that is to say the minimum energy content. The lower sub-range may be a range of the maximum energy content that includes from the minimum limit value up to a predetermined maximum limit value, i.e., for example, up to 20 percent of the maximum energy content.If the energy content 6 falls below the minimum limit value, the method according to FIG. 2 is continued in a step S 4 a. In step S 4 a, the operating profile 8 of a first category is selected. According to the first category, at least one of the vehicle consumers 4, preferably all the vehicle consumers 4, is deactivated for comfort operation. For this purpose, the operating settings assigned to the first category are transmitted to the vehicle consumers 4.If, on the other hand, the energy content 6 lies within the predefined lower sub-range, the method is continued in a step S 4 b. In step S 4 b, the operating profile of a second category is selected. The operating profile according to the second category has a reduced consumption value of the vehicle consumers 4 in the comfort mode in comparison with at least one third category. This means that the vehicle consumers can continue to be operated or operated within the useful life 6 with low consumption values, that is to say, for example, with low operating settings. The operating values, i.e. possible operating settings for the comfort consumers, for example, can thus be restricted. That is, certain operating values may be deactivated or reduced. For example, the maximum power or the maximum number of turn-ons or the turn-on time can be reduced. For this purpose, the operating settings assigned to the second category are transmitted to the vehicle consumers 4.If, on the other hand, the energy content 6 is in a remaining part of the maximum energy content, i.e. for example in an upper sub-region, the method is continued in a step S 4 c. In step S4c, the operation profile of the third category is selected. In the third category, for example, unrestricted operation of the vehicle consumers 4 in the comfort mode can be enabled. For this purpose, the operating settings assigned to the third category are transmitted to the vehicle consumers 4.As a result, the vehicle consumers 4 can be effectively operated further for the remaining useful life. For example, steady operation of the vehicle loads 4 within the useful life 7 may be ensured.In the following, it is summarized once again how the available energy content 6 can be determined or calculated for comfort operation.The minimum energy content for the emergency pulse results, for example, from requirements for a voltage level to be met at least, i.e., for example, a minimum voltage which must be provided with the vehicle battery 2 for carrying out the safety function. The voltage level, i.e. the assigned voltage value, results in a limit resistance, i.e. a limit value for the internal resistance Ri of the vehicle battery 2, which must not be exceeded. This limiting resistance can be defined as a critical internal resistance of the vehicle battery 2.To determine this limit resistance, it is possible, for example, to determine a method known per se for evaluating the on-board electrical system faults occurring in the on-board electrical system, a so-called current ripple or ripple current. The expected response of the on-board power supply system and in particular of the vehicle battery 2 to a current pulse and a continuous load, which results from the emergency pulse, for example, can be predicted from the internal resistance value. The reaction can relate, for example, to a change, in particular a fluctuation, in the vehicle electrical system voltage or the voltage of the vehicle battery 2. If this voltage reaches a critical lower limit, for example as a delta to a necessary minimum voltage for operating the safety-relevant loads, which jeopardizes the operation of the safety-relevant loads in the motor vehicle 1, the internal resistance value assigned to the voltage is defined as the critical limit resistance. Preferably, further critical internal resistance values can additionally be known from other applications, i.e. for example at other operating points of the on-board power supply system. Such further critical internal resistance values can result, for example, in redundant operation with permanent negative energy balances or in the case of shutdown with greatly deviating discharge currents. A systemic critical internal resistance can then be determined, for example, from the minimum of the resistances.Charge contents or energy contents (total energy content and minimum energy content) are calculated from the currently determined internal resistance and the limit resistance, the difference of which reflects the remaining usability, i.e. the comfort energy of the memory.Since the energy content of a vehicle battery 2 is generally a variable variable, the temperature value and the battery characteristic curve, by which, for example, a state of charge or a capacity of the vehicle battery 2 can be predefined, can additionally be taken into account. In addition, the current discharge current of the vehicle battery 2, i.e. the current intensity which is currently required for operation by the connected vehicle consumers 4, can also be taken into account.For example, a compensated internal resistance value can be determined from the battery characteristic data 5. The compensated internal resistance value can be calculated, for example, from the respectively measured internal resistance value Ri from the ripple current, a temperature correction value assigned to the temperature value 5 a, a state of charge correction value assigned to a state of charge and a current correction value assigned to the current discharge current I. The state-of-charge correction value can be derived from the battery characteristic curve, for example. The correction values may be resistance values and may be given in the unit "Ohm".A respective energy content or charge content can then be determined for the compensated internal resistance value for the total energy content and the minimum energy content according to a predefined assignment rule. According to the assignment rule, the assignment can be carried out, for example, using an assignment table or lookup table. The difference between the resulting energy contents, i.e. the total energy content and the minimum energy content, can reflect the remaining usability of the vehicle battery 2.The technical implementation may be realized, for example, as follows. For the limit resistance, a resistance-based state-of-charge correction value associated with the internal resistance can be calculated while compensating the current temperature at room temperature and taking into account a rated capacity of the vehicle battery 2.Now, knowing the nominal capacity of the storage and a percentage capacity utilization transmitted by a battery sensor system, the minimum energy content of the limit resistance can be determined from the state of charge correction value, which minimum energy content is required at least for supplying the safety-critical consumers.In parallel, the current resistance-based state of charge (SoC) can be determined from the current internal resistance measured by the battery sensor system and, as a result, the current resistance-based energy content can be determined therefrom. The difference between the two resistance-based energy contents (current limit) thus yields the energy content 6, which is still available for use of the memory in the current shutdown phase.Alternatively, the energy content 6 for comfort operation can be calculated directly from the battery characteristics 5, for example, wherein a different battery characteristic curve is used than for the determination of the minimum energy content, for example.Overall, the present exemplary embodiments show how a charge content of a battery is predicted above a safety margin and an operating profile for vehicle consumers 4 in comfort operation can be determined therefrom.

Claims

Method for determining an operating profile (8) for comfort operation of vehicle consumers (4), comprising the following steps: - determining an available energy content (6) of a vehicle battery (2) for comfort operation as a function of predefined battery characteristics (5) at least comprising: an internal resistance value (Ri) from a measured ripple current, a temperature value (5a), a predefined battery characteristic curve (5b) and a current discharge current (I) of the vehicle battery (2), characterized bythe following steps: - determining a desired useful life (7) of the comfort operation of the vehicle consumers (4), - defining the operating profile (8) for comfort operation of the vehicle consumers (4) within the useful life (7) as a function of the available energy content (6) and a predefined consumption value of the vehicle consumers (4), wherein, for determining the available energy content (6) for comfort operation, on the one hand a total energy content of the vehicle battery (2) and on the other hand a minimum energy content for an emergency pulse is determined from the battery characteristics (5), and the available energy content (6) is determined from a difference of the total energy content and the minimum energy content, so that the minimum energy content remains present in the vehicle battery.Method according to claim 1, wherein the operating profile (8) is selected from one of several categories depending on the available energy content (6).Method according to Claim 2, wherein it is checked whether the available energy content (6) falls below a minimum limit value of a maximum energy content of the vehicle battery (2) predefined for comfort operation, and an operating profile (8) of a first category is selected only if a result of the check is positive, according to which at least one of the vehicle consumers (4) is deactivated.Method according to one of the preceding claims 2 to 3, wherein it is checked whether the available energy content (6) lies in a predefined lower sub-range of a maximum energy content of the vehicle battery (2) predefined for comfort operation, and only if a result of the check is positive is an operating profile (8) of a second category selected, which comprises a reduced consumption value of the vehicle consumers (4) compared to at least one third category.Battery monitoring device (3) for a vehicle battery (2) which is designed to carry out a method according to one of the preceding claims.Motor vehicle (1) having a vehicle battery (2) and a battery monitoring device (3) according to Claim 5.

Images