DE102020211986A1 - Method and device for individually determining the state of charge of a battery of a battery-operated machine depending on the aging state of the battery - Google Patents

Abstract

The invention relates to a method for determining a state of charge (SOC) of a battery (41) in a battery-operated machine (4), with the following steps:
- Determining (S1) a state of health (SOH) of the battery (41) with a state of health model (51) based on operating variables (F) of the battery (41);
- Providing (S2) at least one reference battery model parameter (P _ref ) using a parameter model (52) depending on the state of health (SOH);
- Adapting (S5) the at least one reference battery model parameter (P _ref ) using a respective correction variable (K) which is determined as a function of current operating variables (F) of the battery (41) using a correction model (54);
- Using (S6) a battery model (55) to determine a current state of charge ( _SOC ) of the battery ( 41) to determine;
- Signaling (S7) of the current state of charge (SOC).

Description

technical field

The invention relates to battery-operated machines, in particular motor vehicles such as electric vehicles or hybrid vehicles, and also to measures for determining the state of charge of a battery.

Technical background

The energy supply of electrically operable, battery-operated machines, such as electrically drivable motor vehicles takes place using a battery as an electrical energy store. When operating an electrically drivable motor vehicle, information about the current state of charge of the battery is essential. On the one hand, the driver or a navigation system needs information about the current state of charge in order to plan a possible stop in order to carry out a charging process if necessary. On the other hand, the state of charge is necessary for energy management, in particular for implementing a hybrid strategy in a hybrid drive system.

In today's battery control devices, in addition to the functions for operating the battery, a state of charge model is also stored, which makes it possible to determine the current state of charge from battery current, battery voltage, battery temperature and the like curves. In addition, the state of charge model is parameterized with a large number of parameters, which can also take into account past battery loads. The state of charge model has an open circuit voltage, an internal resistance, a parallel resistance of an RC element and a capacitor capacitance of the RC element as essential parameters, which depend on the aging state of the battery. The consideration of the aging of the battery in the corresponding state of charge model is currently only insufficiently implemented in battery control units, also because the aging state can currently only be specified with insufficient accuracy.

Disclosure of Invention

According to the invention, a method for determining a state of charge of a battery of a battery-operated machine according to claim 1 and a method for operating a central unit for providing a reference state of charge, a method for operating a battery-operated machine and corresponding devices according to the independent claims are provided.

Further developments are specified in the dependent claims.

• - Ermitteln eines Alterungszustands der Batterie mit einem Alterungszustandsmodell basierend auf Betriebsgrößen der Batterie;
• - Bereitstellen mindestens eines Referenz-Batteriemodellparameters mithilfe eines Parametermodells abhängig von dem Alterungszustand;
• - Anpassen des mindestens einen Referenz-Batteriemodellparameters mithilfe einer jeweiligen Korrekturgröße, die abhängig von momentanen Betriebsgrößen der Batterie aus einem Korrekturmodell ermittelt wird;
• - Verwenden eines Ladezustandsmodells, um abhängig von Batteriemodellparametern, die sich aus einer Beaufschlagung des mindestens einen Referenz-Batteriemodellparameters mit der jeweiligen Korrekturgröße ergeben, um einen aktuellen Ladezustand der Batterie zu ermitteln;
• - Signalisieren des aktuellen Ladezustands.

According to a first aspect, a method for operating a system for determining a state of charge of a battery in a battery-operated machine is provided, with the following steps:

• - Determining a state of health of the battery with a state of health model based on operating parameters of the battery;
• - Providing at least one reference battery model parameter using a parameter model depending on the state of health;
• - Adjusting the at least one reference battery model parameter using a respective correction variable, which is determined from a correction model as a function of current operating variables of the battery;
• - Using a state of charge model to determine a current state of charge of the battery depending on battery model parameters that result from an application of the at least one reference battery model parameter with the respective correction variable;
• - Signaling the current state of charge.

Knowledge of the current state of charge of the battery is essential for the operation of a motor vehicle with a battery. The state of charge changes continuously during active operation as a result of charge withdrawal, with the type of operation determining in a non-linear manner how the state of charge of the battery is reduced with a certain charge withdrawal or increased with an increase in charge in the form of a recuperation process (brake energy recovery).

The current state of charge is generally determined using a state of charge model, which indicates a current state of charge of the battery based on operating variables of the battery, such as a battery current, a battery temperature and a battery voltage. The state of charge is usually specified as a percentage of the maximum charge capacity for a fully charged battery. The battery model parameters, which are used to determine the state of charge, include in particular an open-circuit voltage of an individual cell of the battery, an internal resistance value and a parallel resistance value and a capacitor capacitance of an RC element. The battery model parameters in turn depend on an aging state of the battery.

The state of charge model includes a battery model and an allocation model. The battery model is used to determine a voltage of the battery or an individual cell voltage, which corresponds to a terminal voltage of an individual battery cell, using battery model parameters. The assignment model is used to output a current state of charge depending on a current aging state of the battery, a current temperature and a modeled open-circuit voltage (individual cell voltage). The mapping model is based on measurements and implemented to map modeled open circuit voltages to a state of charge.

The state of health of the battery can be estimated based on a predetermined state of health model from operating variables of the battery.

Parameterizing the battery model depending on the battery model parameters, which depend on the aging state, and the current operating variables, which indicate the current operating state, is very complex, especially since determining the aging state requires a aging state model that is also complex to calibrate. An implementation in a battery control device in a mobile machine, in particular, is therefore very resource-intensive.

A method is therefore proposed for determining the state of charge precisely and in particular as a function of a determined aging state of the battery.

For this purpose, a model structure is initially provided in order to provide reference battery model parameters with the aid of a parameter model depending on a determined aging state. Battery model parameters determined from this can each be subjected to a correction variable that results from a correction model. For this purpose, the correction model uses the operating state determined by the current operating variables of the battery in order to determine the correction variables continuously, in particular as a function of the current state of charge.

Such a model structure enables a resource-saving implementation of a model with which the current state of charge can be determined very precisely. This allows a user of a machine to use the information about the current state of charge in order to plan a possible stop for a charging process and/or to determine a remaining range and an available power very precisely. Information about the state of charge is also necessary for the implementation of a hybrid strategy in a hybrid drive system.

According to one embodiment, the state of health model and the parameter model can be implemented outside the machine in a central unit, the operating parameters of the battery being transmitted to the central unit and the at least one reference battery model parameter being transmitted to the machine by the central unit.

Such a distributed architecture allows the resource expenditure in the machine to be reduced. This enables the use of a state of health model for the very precise machine-external determination of a current state of health of a specific battery, in particular by evaluating fleet data from a large number of battery-operated machines. The reference battery model parameters can then be assigned to this aging state using a parameter characteristic map.

The implementation of the parameter map in the central unit also enables the parameter model to be continuously refined/updated for improved determination of the state of charge. By transmitting the reference battery model parameters to the relevant machine, the battery model can be used there in the state of charge model with the reference battery model parameters for calculating the current state of charge. For this purpose, the reference battery model parameters are corrected using the correction model depending on the current operating variables of the battery, so that a precise current state of charge can always be determined.

As a result, it is provided that the variables that change slowly, i.e. in the time regime of days or weeks, are calculated in the central unit, while the more rapidly changing state of charge is calculated as a function of the very quickly changing operating variables in the machine in question. This represents an optimized trade-off between resource requirements (computing power and memory requirements) in the machine and the bandwidth required for the transmission of data between the machines of the large number of machines and the central unit.

In connection with the external central unit, a state of charge model that is dependent on the aging state of the battery can thus be made available in the machine at any time, which makes it possible to provide a modeled current state of charge. The modeled current state of charge thus offers a certain redundancy to the state of charge resulting from a measured individual cell voltage or terminal voltage of the battery, and on the other hand, an improved prediction of the remaining range is possible, which results from a predicted battery current and battery temperature curve based on the current state of charge model.

Furthermore, the correction model for the at least one reference battery model parameter can specify the relevant correction variable as a function of a current battery current, a current battery temperature and a current state of charge of the battery.

Provision can be made for the correction model to be designed for the at least one reference battery model parameter using one or more characteristic diagrams.

Furthermore, the reference battery model parameters can be updated regularly or at predetermined times.

Furthermore, the aging status can be transmitted from the central unit to the machine, with the correction model for the at least one reference battery model parameter being selected from a number of correction models provided depending on the aging status from a number of correction models.

Provision can be made for the state of charge model to model a current individual cell voltage which corresponds to an open circuit voltage of an individual cell of the battery, with the current modeled individual cell voltage being mapped to the current state of charge using a predefined assignment model.

In particular, the currently modeled individual cell voltage can be compared with a measured individual cell voltage and, depending on a deviation, the central unit can request an update of the reference battery model parameters.

• - Empfangen von Betriebsgrößen einer Batterie;
• - Ermitteln eines Alterungszustands der Batterie mit einem Alterungszustandsmodell basierend auf den Betriebsgrößen der Batterie;
• - Bereitstellen mindestens eines Referenz-Batteriemodellparameters mithilfe eines vorgegeben Parametermodells abhängig von dem Alterungszustand.

According to a further aspect, a method for operating a central unit for providing reference battery model parameters for a battery-operated machine, in particular for the above method, is provided, with the following steps:

• - Receiving operating parameters of a battery;
• - Determining a state of health of the battery with a state of health model based on the operating parameters of the battery;
• - Providing at least one reference battery model parameter using a predetermined parameter model depending on the state of health.

• - Empfangen mindestens eines Referenz-Batteriemodellparameters;
• - Anpassen des mindestens einen Referenz-Batteriemodellparameters mithilfe einer jeweiligen Korrekturgröße, die abhängig von momentanen Betriebsgrößen aus einem Korrekturmodell ermittelt wird;
• - Verwenden eines Ladezustandsmodells, um abhängig von Batteriemodellparametern, die sich aus einer Beaufschlagung des mindestens einen Referenz-Batteriemodellparameters mit der jeweiligen Korrekturgröße ergeben, einen aktuellen Ladezustand der Batterie zu ermitteln;
• - Signalisieren des aktuellen Ladezustands.

According to a further aspect, a method for operating a battery-operated machine for determining a state of charge of a battery in the machine is provided, with the following steps:

• - receiving at least one reference battery model parameter;
• - Adjusting the at least one reference battery model parameter using a respective correction variable, which is determined as a function of current operating variables from a correction model;
• - Using a state of charge model in order to determine a current state of charge of the battery as a function of battery model parameters which result from an application of the respective correction variable to the at least one reference battery model parameter;
• - Signaling the current state of charge.

• - Ermitteln eines Alterungszustands der Batterie mit einem Alterungszustandsmodell basierend auf Betriebsgrößen der Batterie;
• - Bereitstellen mindestens eines Referenz-Batteriemodellparameters mithilfe eines Parametermodells abhängig von dem Alterungszustand;
• - Anpassen des mindestens einen Referenz-Batteriemodellparameters mithilfe einer jeweiligen Korrekturgröße, die abhängig von momentanen Betriebsgrößen der Batterie aus einem Korrekturmodell ermittelt wird;
• - Verwenden eines Batteriemodells, um abhängig von Batteriemodellparametern, die sich aus einer Beaufschlagung des mindestens einen Referenz-Batteriemodellparameters mit der jeweiligen Korrekturgröße (K) ergeben, um einen aktuellen Ladezustand der Batterie zu ermitteln;
• - Signalisieren des aktuellen Ladezustands.

According to a further aspect, a system for determining a state of charge of a battery in a battery-operated machine is provided, the system being designed for:

• - Determining a state of health of the battery with a state of health model based on operating parameters of the battery;
• - Providing at least one reference battery model parameter using a parameter model depending on the state of health;
• - Adjusting the at least one reference battery model parameter using a respective correction variable, which is determined from a correction model as a function of current operating variables of the battery;
• - Using a battery model in order to determine a current state of charge of the battery depending on battery model parameters which result from an application of the at least one reference battery model parameter with the respective correction variable (K);
• - Signaling the current state of charge.

• - Empfangen von Betriebsgrößen einer Batterie;
• - Ermitteln eines Alterungszustands der Batterie mit einem Alterungszustandsmodell basierend auf den Betriebsgrößen der Batterie;
• - Bereitstellen mindestens eines Referenz-Batteriemodellparameters mithilfe eines vorgegeben Parametermodells abhängig von dem Alterungszustand.

According to a further aspect, a device, in particular a data processing unit in a central unit, is provided for providing reference battery model parameters for a battery-operated machine, in particular for the above method, the device being designed for:

• - Receiving operating parameters of a battery;
• - Determining a state of health of the battery with a state of health model based on the operating parameters of the battery;
• - Providing at least one reference battery model parameter using a predetermined parameter model depending on the state of health.

• - Empfangen mindestens eines Referenz-Batteriemodellparameters;
• - Anpassen des mindestens einen Referenz-Batteriemodellparameters mithilfe einer jeweiligen Korrekturgröße, die abhängig von momentanen Betriebsgrößen aus einem Korrekturmodell ermittelt wird;
• - Verwenden eines Batteriemodells, um abhängig von Batteriemodellparametern, die sich aus einer Beaufschlagung des mindestens einen Referenz-Batteriemodellparameters mit der jeweiligen Korrekturgröße ergeben, einen aktuellen Ladezustand der Batterie zu ermitteln;
• - Signalisieren des aktuellen Ladezustands.

According to a further aspect, a device, in particular a control unit in a battery-operated machine, is provided for determining a state of charge of a battery in the machine, with the following steps:

• - receiving at least one reference battery model parameter;
• - Adjusting the at least one reference battery model parameter using a respective correction variable, which is determined as a function of current operating variables from a correction model;
• - Using a battery model in order to determine a current state of charge of the battery as a function of battery model parameters which result from an application of the respective correction variable to the at least one reference battery model parameter;
• - Signaling the current state of charge.

Furthermore, one of the above devices can be provided in a motor vehicle, a pedelec, an aircraft, in particular a drone, a machine tool and/or a household appliance.

character list

• 1 eine schematische Darstellung eines Systems zum Bereitstellen von Batteriemodellparametern durch eine Zentraleinheit an Kraftfahrzeug einer Fahrzeugflotte basierend auf Flottendaten;
• 2 eine schematische Funktionsblockdarstellung eines Ablaufs zum Ermitteln eines modellierten Ladezustands einer Batterie eines bestimmten Kraftfahrzeugs der Fahrzeugflotte; und
• 3 ein Flussdiagramm zur Veranschaulichung eines Verfahrens zum Ermitteln eines modellierten Ladezustands in einem Kraftfahrzeug;
• 4 eine beispielhafte Darstellung eines Kennfelds eines Korrekturmodells zum Bestimmen einer Korrekturgröße; und
• 5 ein Flussdiagramm zur Veranschaulichung eines Verfahren zum Aktualisieren des Ladezustandsmodells.

Embodiments are explained in more detail below with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a system for providing battery model parameters by a central unit on motor vehicles of a vehicle fleet based on fleet data;
• 2 a schematic functional block diagram of a process for determining a modeled state of charge of a battery of a specific motor vehicle in the vehicle fleet; and
• 3 a flowchart to illustrate a method for determining a modeled state of charge in a motor vehicle;
• 4 an exemplary representation of a map of a correction model for determining a correction variable; and
• 5 a flowchart to illustrate a method for updating the state of charge model.

Description of Embodiments

The method according to the invention is described below using vehicle batteries as the battery in a large number of motor vehicles as battery-operated machines. A state of charge model for the respective battery can be implemented in a control unit in motor vehicles. The state of charge model can be continuously updated or corrected or reparameterized using a central unit based on operating variables of the vehicle batteries from the vehicle fleet.

The above example is representative of a large number of stationary or mobile machines with a network-independent energy supply, such as vehicles (electric vehicles, pedelecs, etc.), systems, machine tools, household appliances, IOT devices and the like, which have a corresponding communication connection (e.g. LAN, Internet) connected to a central unit (cloud).

1 shows a system 1 with a central unit 2 which is in combination with a large number of motor vehicles 4 in a vehicle fleet 3 . One of the motor vehicles 4 is representative of the other motor vehicles in 1 shown in more detail.

The motor vehicles 4 each have a battery 41 (traction battery) as a rechargeable electrical energy store, an electric drive motor 42 and a control unit 43, which together form a drive system as is known from the prior art.

The control unit 43 is connected to a communication module 44 which is suitable for transmitting data between the respective motor vehicle 4 and the central unit 2 (a so-called cloud). Operating variables of the battery are detected in a manner known per se using a sensor system 45 .

The central unit 2 has a data processing unit 21 in which the method described below can be carried out, and a database 22 for storing the aging status of batteries in a large number of vehicles 4 in the vehicle fleet 3 .

The operating variables at least indicate variables on which the aging state of the battery depends. The operating variables F can specify a battery current curve, a battery voltage curve (terminal voltage), a battery temperature curve and a charge state curve. The operating variables F are recorded in a rapid time frame of 2 to 100 Hz and can be regularly transmitted to the central unit 2 in uncompressed and/or compressed form. For example, the time series can be transmitted to the central unit 2 in blocks at intervals of 10 minutes to several hours.

From the operating variables F, two operating features can be generated in the central unit 2 or, in other embodiments, operating features can already be generated in the respective motor vehicles 4, which relate to an evaluation period. The operating characteristics serve to determine an aging condition. These are determined for consecutive evaluation periods of a few hours (e.g. six hours) up to several weeks (e.g. one month). A usual value for the evaluation period is one week.

The operating characteristics can include, for example, characteristics relating to the evaluation period and/or accumulated characteristics and/or statistical values ascertained over the entire service life to date. In particular, the operating characteristics can include, for example: Histogram data on the course of the state of charge, the temperature, the battery voltage, the battery current, in particular histogram data with regard to the battery temperature distribution over the state of charge, the charging current distribution over the temperature and/or the discharging current distribution over the temperature, the accumulated total charge (Ah) , an average increase in capacity during a charge (particularly for charges where the increase in charge is above a threshold proportion (e.g. 20%) of the total battery capacity), a maximum of the differential capacity (dQ/dU: change in charge divided by change in battery voltage) and more.

Furthermore, a parameter model is implemented in the central unit 2 which, depending on the aging state for the relevant battery 41 of the motor vehicle 4, provides reference battery model parameters Pref for a battery model of a state of charge model. The reference battery model parameters Pref serve as electrical model parameters for a physical battery model, with which the state of charge SOC of the relevant battery 41 is to be determined together with an allocation model.

In 2 1 is a block diagram to illustrate the function that is executed in the system 1 with the central unit 2 and the respective vehicle 4 of the vehicle fleet 3 in more detail. 3 FIG. 12 is a flow chart showing a method performed in the system 1. FIG. The method can be executed in the control unit 43 of the relevant motor vehicle 4 and in the data processing unit 21 of the central unit 2 . The method for determining a state of charge SOC is described in more detail below for a motor vehicle 4 of the vehicle fleet 3 by way of example.

In step S1, the operating variables F of the battery 41 are transmitted to the state of health model 51 in the central unit 2, as described above. The operating variables F are combined into operating characteristics. Operating variables F and operating characteristics can be processed in the physically based or data-based state of health model 51 for each evaluation period in order to obtain the current state of health SOH.

The aging state (SOH: state of health) is the key variable for specifying a remaining maximum battery capacity or remaining maximum battery charge. Aging can be expressed as capacity retention rate (SOH-C) or as internal resistance increase (SOH-R). The capacity retention rate SOH-C is given as a ratio of the measured instantaneous capacity to an initial capacity of the fully charged battery. The relative change in the internal resistance SOH-R increases as the battery 41 ages. The aging status can be provided accordingly as SOH-C or SOH-R.

In step S2, the state of health SOH of the battery 41 modeled in this way is supplied to a parameter model 52 in the central unit 2, which can be provided, for example, as a characteristic diagram, as a lookup table or also as a function or based on data. The parameter model 52 supplies reference battery model parameters Pref for a state of charge model 53 which is implemented in the vehicles 4 of the vehicle fleet 3 . The reference battery model parameters Pref include, for example, an open-circuit voltage Uocv, an internal resistance of the battery, a parallel resistance and a capacitance of one or more RC elements of a battery replacement circuit of the battery 41. These electrical battery model parameters are subject to aging, so that the electrical reference Battery model parameters Pref can be adapted to the state of health SOH of the respective battery 41 .

The state of charge model 53 includes a battery model 55 and an allocation model 56. The battery model 55 is used to determine a voltage of the battery or an individual cell voltage, which corresponds to a terminal voltage of an individual battery cell, using battery model parameters. The assignment model is used to output a current state of charge depending on a current aging state of the battery, a current temperature and a modeled open circuit voltage. The mapping model is based on measurements and implemented to map modeled open circuit voltages to a state of charge.

The reference battery model parameters Pref depend to a considerable extent on a current operating state of the battery 41 . Since the current operating state of the battery 41 in the central unit 2 cannot be reliably available at all times and in order to reduce the amount of data to be transmitted between the motor vehicle and the central unit 2, reference battery model parameters Pref are provided which refer to a specific predetermined reference - Obtain the operating point of the battery 41. For example, the reference battery model parameters Pref may relate to an operating point, such as a battery current of 10A, a battery temperature of 30°C and a state of charge of 50%.

In step S3, the reference battery model parameters Pref are then transmitted to the respective motor vehicle 4 of the vehicle fleet 3 together with the current aging status.

In order to quickly adjust the reference battery model parameters Pref to the respective state of charge SOC (state of charge) and the operating state of the battery 41, the reference battery model parameters Pref are adjusted in step S4 using a correction model 54 in a fast time frame of between 1 Hz and 100 Hz . The time frame of the adjustment can correspond to a time frame of the detection of operating variables F in the vehicle.

The operating variables include a current battery current I, a current battery temperature T and a current state of charge SOC of the battery 41. According to these operating variables, a correction variable for each of the reference battery model parameters Pref is determined using a respective characteristic diagram. Such a map, as exemplified in 4 shown for one of the reference battery model parameters Pref, is selected according to the state of health SOH and can output a correction factor k depending on the current battery current I, the current battery temperature T and the current state of charge SOC, with which the relevant reference battery model parameter Pref is applied. A plurality of such characteristics maps for different aging states SOH or aging state ranges and for each of the reference battery model parameters Pref can be kept in the control unit 43 of the relevant motor vehicle 4 .

This in 4 The map shown as an example indicates a factor for one of the reference battery model parameters Pref depending on the instantaneous battery current I and the instantaneous state of charge SOC, by which the relevant reference battery model parameter Pref should be increased or decreased. A third or further dimension, such as that of the current battery temperature, is not shown for reasons of clarity. A correction factor is thus provided as correction variable K for each of the reference battery model parameters Pref, with which the reference battery model parameters Pref provided by the central unit 2 are adjusted. The correction variables K can be applied to the reference battery model parameters Pref multiplicatively, additively or in some other way.

In step S5, the battery model 55 is supplied with the correction variables K, which are offset against the reference battery model parameters Pref in the battery model 55 in order to obtain the applied battery model parameters.

In step S6, the battery model 55 determines the individual cell voltage, which is used to determine the current state of charge.

The battery model 55 may be modeled according to an open circuit voltage □ocv = □ - □RC1 - □RC2 - □ □R0
determine, where Uocv corresponds to the open-circuit voltage, U to the current battery voltage, I to the current battery current, R0 to the series resistance and U _RC1 and U _RC2 to the voltage drops across the serial RC elements of the battery replacement circuit. A current state of charge is determined from the modeled no-load voltage Uocv according to the assignment model 56 by evaluating a corresponding data map.

As a rule, the battery model 55 is used to model an open-circuit voltage of an individual cell, which corresponds to the terminal voltage of the battery 41 as a function of the current current load. This modeled individual cell voltage is representative of the state of charge and can be assigned to the current state of charge SOC using the assignment model 56 implemented in the state of charge model 53, such as a lookup table.

In the subsequent step S7, the current state of charge SOC can be signaled in order to use it for subsequent vehicle functions and/or to output it to the driver.

In 5 a flow chart is shown to illustrate a method that triggers the updating of the reference battery model parameters Pref of the battery model 55 from the central unit 2 . This can take place, for example, at defined points in time outside the operating times of the motor vehicle 4 or immediately at the start of the journey. The method is carried out in the control unit 43 of the motor vehicle 4 .

The method also provides for the reference battery model parameters Pref to be updated when requested by the motor vehicle 4 .

In step S11 the open-circuit voltages of the individual cells of the battery 41 are measured in particular with the aid of the sensor system 45 .

In step S12, the individual cell voltages of the individual battery cells are checked for plausibility and a representative value of the individual cell voltage is calculated from the measured individual cell voltages, for example by averaging. Other methods can be used, such as outlier elimination or averaging of minimum and maximum individual cell voltages.

In step S13, a modeled open circuit voltage of the battery 41 is determined using the battery model 55 described above.

In step S14 it is checked whether there is a deviation between the modeled no-load voltage, which is determined in the battery model 55, and an no-load voltage by more than a predetermined threshold value.

If there is no deviation (alternative: no), the method continues with step S11 without updated reference battery model parameters Pref being requested.

If there is a discrepancy (alternative: yes), the method continues with step S15, updated reference battery model parameters Pref being requested from the central unit 2 .

In step S16 the newly determined reference battery model parameters Pref are then received in motor vehicle 4 and used in battery model 55 .

Furthermore, in step S17 an error counter is incremented, which is intended to determine the number of discrepancies between the measured and modeled no-load terminal voltage within a period of time.

In step S18, a check is made as to whether a predetermined number of new requests for the reference battery model parameters Pref have taken place within a predetermined period of time, for example one more week. If it is determined in step S18 that a predetermined number of new requests for the reference battery model parameters has taken place within a predetermined period of, for example, one week (alternative: yes), then a faulty model or a faulty battery is concluded and this is reported to the driver as a fault signaled in step S19. Otherwise, the process jumps back to step S11.

Claims (16)

Method for determining a state of charge (SOC) of a battery (41) in a battery-operated machine (4), with the following steps: - determining (S1) a state of health (SOH) of the battery (41) with a state of health model (51) based on operating variables ( F) the battery (41); - Providing (S2) at least one reference battery model parameter (P _ref ) using a parameter model (52) depending on the state of health (SOH); - Adapting (S5) the at least one reference battery model parameter (P _ref ) using a respective correction variable (K) which is determined as a function of current operating variables (F) of the battery (41) using a correction model (54); - Using (S6) a battery model (55) to determine a current state of charge ( _SOC ) of the battery ( 41) to determine; - Signaling (S7) of the current state of charge (SOC). procedure after claim 1 , wherein the correction model (54) for the at least one reference battery model parameter (P _ref ) indicates the relevant correction variable (K) depending on a current battery current, a current battery temperature and a current state of charge (SOC) of the battery (41). Procedure according to one of Claims 1 until 2 , wherein the correction model (54) for the at least one reference battery model parameter (P _ref ) is formed using one or more characteristic diagrams. Procedure according to one of Claims 1 until 3 , wherein the updating of the reference battery model parameters (P _ref ) is carried out regularly or at predetermined times. Procedure according to one of Claims 1 until 4 , wherein the state of health model (51) and the parameter model (52) are implemented external to the machine in a central unit (2), the operating parameters of the battery (41) being transmitted to the central unit (2) and the at least one reference battery model parameter (P _ref ) is transmitted to the machine (4) by the central unit (2). procedure after claim 5 , wherein the state of health (SOH) is transmitted from the central unit (2) to the machine (4), wherein the correction model (54) for the at least one reference battery model parameter (P _ref ) from a plurality of provided correction models depending on the state of health (SOH) is selected from several correction models. Procedure according to one of Claims 5 until 6 , wherein the battery model (55) models a current individual cell voltage which corresponds to an open-circuit voltage (U _ocv ) of an individual cell of the battery (41), the current modeled individual cell voltage being mapped to the current state of charge (SOC) using an allocation model (56). procedure after claim 7 , wherein the current modeled individual cell voltage is compared with a measured individual cell voltage and depending on a deviation, an update of the reference battery model parameters (P _ref ) is requested by the central unit (2). Method for operating a central unit for providing reference battery model parameters (P _ref ) for a battery-operated machine (4), in particular for a method according to one of Claims 1 until 8th , with the following steps: - Receiving operating parameters (F) of a battery (41); - Determining (S1) a state of health (SOH) of the battery (41) with a state of health model (51) based on the operating variables (F) of the battery (41); - Providing at least one reference battery model parameter (P _ref ) using a predetermined parameter model (52) depending on the state of health (SOH). Method for operating a battery-operated machine (4) to determine a state of charge (SOC) of a battery (41) in the machine (4), with the following steps: - receiving (S3) at least one reference battery model parameter (P _ref ); - Adapting the at least one reference battery model parameter (P _ref ) using a respective correction variable (K), which is determined as a function of current operating variables (F) from a correction model (54); - Using (S6) a battery model (55) to calculate a current state of charge ( _SOC ) of the battery (41 ) to determine; - Signaling (S7) of the current state of charge (SOC). System for determining a state of charge (SOC) of a battery (41) in a battery-operated machine (4), the system being designed to: - determine a state of health (SOH) of the battery (41) with a state of health model (51) based on operating variables of Battery; - Providing at least one reference battery model parameter (P _ref ) using a parameter model (52) depending on the state of health (SOH); - Adapting the at least one reference battery model parameter (P _ref ) using a respective correction variable (K) which is determined from a correction model (54) as a function of current operating variables of the battery (41); - Using a battery model (55) in order to obtain a current state of charge (SOC) of the battery (41) depending on battery model parameters that result from applying the respective correction variable (K) to the at least one reference battery model parameter (P _ref ). determine; - Signaling the current state of charge (SOC). Device, in particular a data processing unit (21) in a central unit (2), for providing reference battery model parameters (P _ref ) for a battery-operated machine (4), in particular for a method according to one of Claims 1 until 8th , wherein the device is designed to: - receive operating parameters (F) of a battery (41); - Determining a state of health (SOH) of the battery (41) with a state of health model (51) based on the operating parameters of the battery (41); - Providing at least one reference battery model parameter (P _ref ) using a predetermined parameter model (52) depending on the state of health (SOH). Device, in particular a control unit (43) in a battery-operated machine (4), for determining a state of charge (SOC) of a battery (41) in the machine (4), with the following steps: - receiving at least one reference battery model parameter (P _ref ); - Adapting the at least one reference battery model parameter (P _ref ) using a respective correction variable (K), which is determined as a function of current operating variables (F) from a correction model (54); - Using a battery model (55) to determine a current state of charge of the battery (41) as a function of battery model parameters which result from an application of the at least one reference battery model parameter (P _ref ) to the respective correction variable (K); - Signaling the current state of charge (SOC). use of the device Claim 13 in a motor vehicle, a pedelec, an aircraft, in particular a drone, a machine tool and/or a household appliance. Computer program product comprising instructions which, when the program is executed, cause at least one data processing device to carry out the steps of the method according to one of the Claims 1 until 11 to execute. Machine-readable storage medium, comprising instructions which, when executed by at least one data processing device, cause the latter to carry out the steps of the method according to one of Claims 1 until 11 to execute.

Images