CN118050641A - Method and device for determining the aging state of a device battery by means of a networked power supply station - Google Patents

Method and device for determining the aging state of a device battery by means of a networked power supply station Download PDF

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Publication number
CN118050641A
CN118050641A CN202311652671.1A CN202311652671A CN118050641A CN 118050641 A CN118050641 A CN 118050641A CN 202311652671 A CN202311652671 A CN 202311652671A CN 118050641 A CN118050641 A CN 118050641A
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China
Prior art keywords
state
battery
charge
aging
aging state
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C·西莫尼斯
S·辛德勒
S·莎德
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Robert Bosch GmbH
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Robert Bosch GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/16—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
    • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
    • B60L3/0046—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to electric energy storage systems, e.g. batteries or capacitors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/10—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles characterised by the energy transfer between the charging station and the vehicle
    • B60L53/14—Conductive energy transfer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/60—Monitoring or controlling charging stations
    • B60L53/62—Monitoring or controlling charging stations in response to charging parameters, e.g. current, voltage or electrical charge
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/392—Determining battery ageing or deterioration, e.g. state of health
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/54—Drive Train control parameters related to batteries
    • B60L2240/547—Voltage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/70—Interactions with external data bases, e.g. traffic centres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/70—Interactions with external data bases, e.g. traffic centres
    • B60L2240/72—Charging station selection relying on external data

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Sustainable Energy (AREA)
  • Sustainable Development (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

The invention relates to a method for determining the aging state of a device battery by means of a power supply station, which is connected in communication to a central unit, comprising the steps of: performing a discharging or charging process from a first to a second state of charge on the device battery by providing a charging or discharging current by the power supply station; measuring a battery static voltage in the power supply station in a first and a second state of charge and/or measuring a corresponding resistance gradient when a stepped charging current edge is applied, wherein the first and the second state of charge are determined by a predefined path voltage characteristic curve in dependence on the battery static voltage; ascertaining a preliminary aging state in the power supply station from the measurement of the battery static voltage or the measurement of the resistance gradient in the first and second states of charge; the aging state in the central unit is determined by means of an aging state model as a function of the preliminary aging state and the further operating characteristic, wherein the aging state model is designed to output the aging state as a function of the preliminary aging state and the further operating characteristic.

Description

Method and device for determining the aging state of a device battery by means of a networked power supply station
Technical Field
The invention relates to a battery-operated electrical device, in particular an electrically drivable motor vehicle, in particular an electric vehicle or a hybrid vehicle, having a device battery, and also to measures for determining the current State of aging (SoH) of the device battery.
Background
The energy supply of battery-operated electrical devices and machines, for example electrically drivable motor vehicles, is achieved by means of a device battery or a vehicle battery. They provide electrical energy for the operation of the device or vehicle.
The device battery degrades during its lifetime depending on its load or use. This so-called aging results in a continuous decrease in the maximum power capacitance or storage capacitance. The aging state is used to indicate the degree of aging of the device battery. Conventionally, a new device battery has an aging state that is 100% relative to its total capacitive aging state available, which can drop significantly over its lifetime. The extent to which the device battery ages (change in the aging state over time) depends on the individual load of the device battery, i.e. in the case of a vehicle battery of a motor vehicle, on the behavior of the driver in use, the external environmental conditions and the type of vehicle battery.
The state of ageing (SOH) of the equipment battery is read by a diagnostic device via an OBD interface during the repair of the vehicle battery in the repair station, and the value of the state of ageing is calculated and stored in a battery control unit (BCU, english: battery Control Unit). These aging state values are determined beforehand by the battery control unit during or after driving, during or after the charging process, in a dynamic or static state, under different conditions and in accordance with the algorithm used for determining the aging state.
Standardized methods for determining the aging state are currently unknown. Generally, the aging state read from the battery control unit is trusted, but it has a high inaccuracy (-5%). The more accurate aging state values provide great advantages and planning reliability for estimating the remainder of the device battery.
Disclosure of Invention
According to the invention, a method for ascertaining the aging state of a device battery of a technical device by means of a networked power supply station according to claim 1 and a corresponding device according to the parallel claim are provided.
Further embodiments are indicated in the dependent claims.
According to a first aspect, a computer-implemented method for determining an aging state of a device battery in a technical device by means of a power supply station, which communicates with a central unit, is provided, the method having the following steps:
-performing a discharging process or charging process from a first State of charge (SOC) to a second State of charge (SOC) on the device battery by providing a charging or discharging current by the power supply station;
In the first and second charging states, the battery static voltage in the power supply station, in particular in the rest state of the device battery, is measured accordingly, and/or in the first and second charging states, when rectangular current edges are applied, the voltage gradient is measured accordingly, wherein the first and second charging states are determined in particular by a predetermined no-load voltage characteristic curve in dependence on the respective battery static voltage;
-ascertaining a preliminary ageing state in the power supply station from measurements of the battery static voltage in the first state of charge and the second state of charge or of the voltage gradient in the first state of charge and the second state of charge;
Determining an aging state in the central unit by means of a data-based aging state model as a function of the preliminary aging state and in particular of the at least one further operating characteristic, wherein the data-based aging state model is designed to output the aging state as a function of the preliminary aging state and in particular of the at least one further operating characteristic.
The aging state of the device battery is often not directly measured. This requires opening the battery cell and measuring it in a test bench measurement or alternatively a series of sensors inside the device battery, which increases the cost of manufacturing such device batteries and the expense and space required. Furthermore, no routinely applicable measurement methods for directly determining the device battery aging state are available on the market.
Currently, the aging state is ascertained in a battery control unit disposed close to the battery and is read during servicing or when the device is being serviced. The provided aging state is ascertained under different conditions and during the driving process or after the charging process depending on the algorithm used for determining the aging state. The methods used at the battery control unit of the battery management system may partially differ significantly, and thus it is often impossible to compare the aging state read out by the battery control unit between vehicles. In addition, inaccuracy can be as high as 5%. In this case, an accurate determination of the aging state is of great importance to the device user, since the remaining service life of the device battery and the future availability of the corresponding device can be derived therefrom.
In a device battery, the state of aging (SOH) is a key parameter for indicating the total capacity of the remaining battery or the remaining endurance in case the battery is fully charged. The aging state is the degree to which the device battery ages. In the case of a device battery, battery module, or battery cell, the aging state can be expressed as a capacitance holding rate (SOH-C, english: capacityRetentionRate). The capacitance holding ratio SOH-C is defined as the ratio of the measured instantaneous capacitance to the initial capacitance of the fully charged battery. This ratio decreases as the degree of aging increases. Or the aging state may also be expressed as an increase in internal resistance (SOH-R) relative to the internal resistance at the beginning of the service life of the device battery. The ratio of the current resistance to the resistance at the beginning of the service life and SOH-R increases as the battery ages.
One possibility for determining the aging state of the device battery consists in using the relationship between the device battery and the battery quiescent voltage, i.e. the dead-end voltage after a sufficiently long rest period (duration after the last current has flowed into or out of the device battery) and the state of charge. The state of charge represents a relationship of the amount of power stored and callable in the device battery with respect to the total amount of power storable. The relationship between the battery static voltage and the corresponding state of charge after a corresponding sufficiently long rest period (time until the time gradient of the battery voltage is less than a predetermined threshold value, for example, time until no 0.01V voltage change occurs within a defined time (for example, 30 minutes)) corresponds to an empty voltage characteristic curve or an OCV characteristic curve (OCV: open Circuit Voltage, open circuit voltage) provided as an OCV model. The OCV model known at present, although describing the relationship of the no-load voltage to the state of charge and, if necessary, to the temperature of the battery, does not take into account the relationship of the no-load voltage to the state of aging and the path dependence of the aging effect. The path dependence of the OCV characteristics with progressive aging changes and aging effects is due to the following reasons: the variation of the battery characteristics during the service life is related to the operating conditions to which the device battery is subjected up to the current point in time, and in what order the operating conditions have an influence on the device battery is decisive.
The above method provides a method that can reliably provide an aging state under controlled conditions in a measured manner. The method uses measurements of the battery static voltage and charge counts (hereinafter "coulombs counts") to determine the aging status of the device battery. The method described above makes it possible to ascertain the aging state of the device battery using the networked power supply station without detecting the operating variable history. The power supply station may be a conventional charging station or may be a bidirectional charging station which is capable of controlling the supply of power to the device battery and the delivery of current to the device battery.
The above method provides for using the networked power supply station for a charging process of the device battery in order to determine the aging state of the device battery during the execution of the charging process. For this purpose, a process is implemented in the power supply station, in which measurements can be carried out under controlled conditions on characteristic variables of the device battery. The method uses measurements of the battery static voltage and coulomb counting to determine the device battery's state of aging associated with the capacitance. Alternatively or additionally, the aging state associated with the change in resistance can also be determined by determining the amount of voltage change of the device battery immediately after the application of the constant charging current.
This method enables ascertaining the preliminary aging state of the device battery without detecting the operation history of the device battery.
The preliminary ageing state is determined from the amount of power provided by the device battery between two rest phases, i.e. between the end time of the rest phase in the first state of charge (for example soc=20%) and the end time of the rest phase in the second state of charge (soc=80%). The charge is obtained by time integrating the total charge current provided by the battery over a period of time.
The ascertained quantity of electricity is then divided by the difference between the charge state thresholds associated with the rest phases (here 80% -20%) and correlated with a reference total capacitance at the beginning of the service life of the device battery, so as to obtain a preliminary ageing state SOH-C related to the capacitance.
Alternatively, the first state of charge threshold value can correspond to a fully discharged state of the device battery, wherein it is determined that the first state of charge is reached when a respective predetermined voltage limit is reached.
The second state of charge threshold value can also correspond to a full state of charge of the device battery, wherein it is determined that the second state of charge is reached when the charge end voltage is reached.
The calculation of the preliminary aging state SOH-C associated with the capacitance is based on a pre-set no-load voltage characteristic associated with the aging state. The above-described determination of the first charge state is based on a no-load voltage characteristic which is selected only as a function of the assumed aging state. Based on the previously determined preliminary state of charge SOH-C associated with the capacitor, a matching no-load voltage characteristic can be selected and the battery static voltage ascertained in the first state of charge can be assigned to the actual state of charge value corresponding to the first state of charge.
It can be provided that, in order to ascertain the preliminary aging state, the method is carried out iteratively between the measured battery static voltage, the preliminary aging state and the corresponding state of charge, in order to minimize errors in the preliminary aging state.
The above method for calculating the preliminary aging state associated with the capacitance can be re-executed in this case, wherein the no-load voltage characteristic curve preset on the basis of the preliminary aging state determined last time is always used. By iteratively performing the above steps, the preliminary aging state gradually converges thereby. Such iterative methods end, for example, when the amount of change in the preliminary aging state in successive iterations is less than a predetermined threshold (e.g., less than 0.5% soh).
In order to carry out the iterative method, it is necessary to prepare a particularly accurate no-load voltage characteristic.
The method described above is characterized in that a state variable of the device battery during a charging process of the power supply station is measured and a preliminary aging state is ascertained therefrom. Based on the aging state model stored in the central unit, the aging state of a specific battery type of the device battery is accurately determined. This can be achieved by providing an aging state of the battery management system that is independent of the specific battery type of the device battery, so that the remaining service life of the device battery or the remaining value of the device battery can be estimated in an improved manner.
The method is characterized in that a method for determining an aging state is provided, which uses an aging-dependent no-load voltage characteristic curve. For this purpose, the respective state of charge is assigned as a function of a measurement of the static voltage of the battery and is correlated to the amount of power supplied for the purpose of achieving the state of charge journey in order to determine the preliminary aging state.
By means of an aging state model implemented in the central unit, the operating characteristics of the device battery during charging, which are transmitted by the power supply station, can be evaluated in order to provide accurate information about the aging state. The preliminary aging state and the at least one operating characteristic are transmitted to the central unit. The at least one additional operating characteristic can include ambient temperature during a charging process or a discharging process, defining a battery quiescent voltage in a state of charge, defining a battery temperature in a state of charge, an extremum of a differential capacitance associated with the battery voltage.
By means of the data-based aging state model in the central unit, the operating characteristics detected by the power supply station can be estimated by means of the data-based aging state model. The data-based aging state model can be designed and trained in the form of a probabilistic regression model, for example a gaussian process model, to assign the preliminary aging state, which is ascertained in the power supply station and is associated with capacitance and/or resistance changes, and at least one of the following parameters to the aging state: the ambient temperature during the charging process, the battery static voltage after a corresponding duration of rest in a predetermined or defined state of charge, the battery temperature during the charging process, the measured variables and/or state variables that can be obtained by the battery management system of the particular battery type, and the differential capacitance calculated on the basis of the smoothed dQ/dU, in particular for the local extremum.
The ageing state model can be provided in a central unit remote from the device or trained with a training data set obtained by accurate measurement of the ageing state of a plurality of device batteries of the same type but with different ageing states in a factory or on a test bench. Alternatively, the above-described operating characteristics used may also be preprocessed with PCA (principal component analysis).
The aging state determined in the central unit can be transmitted in the form of a user certificate to the user of the technical device with the device battery in order to make the user aware of the estimated remaining service life or the remaining value of the device battery. The usage certificate may also include predictive maintenance plans or include abnormal warnings. For example, if there is a difference between the voltage measurement in a specific state of charge and the no-load voltage characteristic curve in an aged state determined by the aged state model, an abnormality can be determined.
In order to determine a preliminary aging state of a device battery in a power supply station on the basis of an aging-related no-load voltage characteristic, battery static voltages at different states of charge are measured and correlated with the amount of power that has to be provided to reach a state of charge stroke in order to determine the preliminary aging state.
The no-load voltage characteristic can be designed on the basis of data, for example in the form of a probabilistic regression model, such as a gaussian process model; or by means of a parametric model, for example a polynomial model, in sections, in the form of spline functions or the like.
The no-load voltage characteristic can be modified in the central unit periodically by parameterizing or training the no-load voltage characteristic based on data from a plurality of device batteries. The adaptation of the no-load voltage characteristic is based on training data points which indicate, for the respective device battery, the relationship between the battery static voltage, the state of charge determined by the existing no-load voltage characteristic and the state of aging determined by the aging state model as described above. The continuous improvement of the used no-load voltage characteristic is realized by adjustment or training. The parameters of the no-load voltage characteristic are transmitted to the power supply station after adjustment or training, so that they can be used there for carrying out the method.
The adjustment or training of the no-load voltage characteristic can be carried out in particular by determining the parameters of the no-load voltage characteristic by minimizing the deviation between the preliminary aging state and the aging state determined in the central unit.
In this way, the dependence of the charge state on the battery static voltage and the determined aging state can be simulated using the no-load voltage characteristic curve, so that the preliminary aging state can be ascertained as described above.
Drawings
Embodiments are described in detail below with reference to the drawings. Wherein:
FIG. 1 shows a schematic diagram of a system having a plurality of charging stations networked with a central unit in order to provide accurate aging status of vehicle batteries of a particular vehicle battery type;
fig. 2 shows a flow chart for explaining a method for determining an aging state of a vehicle battery during a charging process of a charging station; and
FIG. 3 illustrates an exemplary variation curve of battery voltage and battery current for a vehicle battery;
fig. 4 shows exemplary no-load voltage characteristics for two different aging states of a vehicle battery.
Detailed Description
The method according to the invention is described below with reference to a vehicle battery (as a device battery) in a motor vehicle (as a technical device). During the charging process of a charging station (as an example of a power supply station), measurements can be made of the vehicle battery to ascertain the aging state. This measurement allows setting of reconstructable conditions, for example constant battery temperature, so that the aging state can be determined particularly accurately by means of a corresponding aging state model.
The foregoing examples represent a plurality of stationary or mobile devices with battery-powered power sources, such as vehicles (electric vehicles, electric bicycles, etc.), units, machine tools, household appliances, internet of things (IOT) devices, etc., which can be connected via corresponding communication connections (e.g., local area network, internet) to a central unit (cloud) external to the devices.
Fig. 1 shows a system 1 with a charging station 3 and a central unit 2 which is in communication with the charging station 3. The charging station 3 is used to charge a vehicle battery of the electric vehicle 4.
Fig. 1 shows a vehicle train with a plurality of motor vehicles 4. One of which motor vehicle 4 is shown in detail in fig. 1. The motor vehicle 4 has a vehicle battery 41, an electric drive motor 42 and a battery management system 43, respectively. The battery management system 43 is connected to a communication module 44 which is adapted to transmit data between the respective motor vehicle 4 and the charging station 3. The battery management system 43 of the vehicle battery 41 is configured to perform voltage measurement, current measurement, and temperature measurement in the vehicle battery 41, and provide corresponding data specifications.
The vehicle 4 is charged at regular time intervals to supply energy. This can be achieved by connecting it to the charging station 3. By carrying out the method described below, an exact state of aging, in particular a state of aging SOH-C associated with a capacitance and/or a state of aging SOH-R associated with a resistance, can be ascertained for the vehicle battery 41.
The method for ascertaining the aging state evaluates operating variables, which are detected during the charging of the vehicle battery 41 in the charging station 3.
The charging station has a control unit 31 which is capable of reading information from a battery management system 43 of a vehicle battery 41 when the vehicle is charged. Furthermore, the charging station 3 has voltage and current measuring means in order to continuously detect the battery voltage and the battery current during the charging process. Furthermore, the control unit 31 can obtain type information about the battery type of the vehicle battery 41 to be charged at the beginning of the charging process, and, as a function of these type information, assign a charging profile for the upcoming charging process to the vehicle battery 41 (Ladeprofil). The charging curve sets the magnitude of the charging power in advance, in particular, according to the state of charge of the vehicle battery 41.
The charging station 3 has a communication unit 32 for exchanging information with the central unit. The method can be started by the vehicle 4 traveling to the charging station 3 to start the charging process, with which the aging state of the vehicle battery 41 can be accurately determined. Such a method is described in detail below with reference to the flowchart of fig. 2:
In step S1, it is checked whether the charging process for the specific vehicle battery 41 should be started. This can be determined, for example, by determining the connection between the vehicle battery 41 and the charging station 3. If the charging process is to be started (alternatively: yes), the method continues with step S2, otherwise the method returns to step S1.
In step S2, the vehicle battery 41 is placed in a defined state of charge, for example soc=20%. Such a state of charge can preferably correspond to a low state of charge or a fully discharged state. The charging station 3 is also able to discharge the vehicle battery 41 if the actual state of charge of the vehicle battery 41 is higher than the defined state of charge.
The actual state of charge of the vehicle battery 41 can be determined from the no-load voltage characteristic curve implemented in the charging station 3. The no-load voltage characteristic curve, also referred to as OCV characteristic curve, represents the relationship between the battery voltage of the vehicle battery 41 in the no-load state (battery current equal to 0A) and the state of charge (SOC). The no-load voltage characteristic can be defined as a parameter in relation to the state of aging SOH-C, SOH-R of the vehicle battery 41. Examples of such no-load voltage characteristic curves are shown for soh=100% and soh=90%, for example, in fig. 4.
If a defined state of charge is reached, which is identified by the battery voltage reaching a voltage value specified by the no-load voltage characteristic of the associated first state of charge, a rest phase is set in step S3, during which the battery voltage is rest. The duration of the rest phase is determined by the fact that the battery voltage varies below a preset threshold value (e.g. 0.01V) over a predetermined period of time (e.g. over 30 minutes).
By means of the no-load voltage characteristic curve implemented in the control unit 31 of the charging station 3, the battery static voltage reached after the rest phase is compared with the battery voltage specified by the no-load voltage characteristic curve for a defined state of charge. This allows a comparison to be made to define whether the state of charge has been reached. The actual state of charge can be further approximated to the defined state of charge by further charging or discharging, if necessary.
In step S4, a value of the state of charge reconstructed from the no-load voltage characteristic is assigned to the battery static voltage as a first state of charge.
Then, in step S5, a charging process is started, wherein the charging process is controlled according to a charging profile associated with the vehicle battery 41. The charging curve can be defined such that the current-voltage edge (Flanke) at the beginning of the charging process can then also be used to determine an aging state SOH-R, which is associated with a change in resistance and which results from an evaluation of Δu/Δi at the beginning of the charging when the current edge is sufficiently steep.
Preferably, the charging curve has a constant current curve with an edge gradient of a sufficiently high current value at the beginning of the charging.
In step S6, the vehicle battery 41 is placed in a further defined state of charge, for example soc=80% by supplying a charging current. Such further defined states of charge can preferably correspond to high states of charge or fully charged states. During charging, the charging current is kept constant, or in other charging methods, the charging current is continuously detected as a time series.
If the further defined state of charge is reached, which is identified by the battery voltage reaching a voltage value specified by the no-load voltage characteristic of the associated further defined state of charge, a rest phase is provided in step S7, during which the battery voltage is rest. The second state of charge associated with the battery quiescent voltage reached after the rest phase from the no-load voltage characteristic is temporarily stored as the second state of charge.
Furthermore, one or more additional charge states can be initiated during the charging process, including a subsequent rest phase, in which the respective battery static voltage is detected together with the associated charge state. This additional state of charge can preferably be brought to the aging sensitive point of the no-load voltage characteristic curve, for example at a state of charge of 50%.
In step S8, the delivered charge amount can be determined by integrating the measured charge current i (t) over time from the time point t relax,1 at which the first state of charge SOC relax,1 is ascertained to the time point t relax,2 at which the second state of charge SOC relax,2 is ascertained. In order to determine the preliminary state of charge SOHC, the ascertained charge quantity is related to the charge path between the upper and lower charge state thresholds and the total capacitance (nominal capacitance) C 0,ref of the vehicle battery 41 at the beginning of the service life, in particular as follows:
The determination of the state of aging SOH-R associated with the resistance change can be based on an evaluation of the current-voltage edges at the beginning of the charging phase.
Fig. 3 schematically shows how to ascertain the battery static voltage. Fig. 3 shows an exemplary time profile of the battery voltage and the battery current during the driving phase F and the charging phase L. The application cycle of the charging current is set according to a preset charging profile, which is interrupted by a rest phase R for measuring the battery static voltage. Based on the battery static voltage, the actual state of charge is determined from an evaluation of the no-load voltage characteristic curve.
Alternatively, in order to determine the battery static voltage, it is possible to use a voltage measurement point in the rest phase (charging current equal to 0A) just after the phase of the charging process by means of a constant charging current, at which the local time gradient of the battery voltage (in the case of a current of 0A) is below a defined threshold value. This ensures that the comparison can be carried out in the completely deactivated state of the vehicle battery 41, which increases the reliability of the ascertained state of charge.
The preliminary aging state detected in the charging station 3 in this way can then be evaluated by means of a data-based aging state model provided in the central unit 2. The aging state model is based on the operating characteristics provided by the charged vehicle battery 41, which has just ended the charging process at the charging station 3, as input variables, and provides the aging state as output variable. The data-based aging state model can be designed as a probabilistic regression model, for example a gaussian process model, and trained and evaluated in a central unit. The aging state model is assigned to a specific vehicle battery type and can only be used strictly for this battery type.
Here, an exponential quadratic kernel can be used as the kernel of the gaussian process in order to "smoothly" model a slowly time-varying system with "slow" battery aging.
For this purpose, the operating characteristics that can be evaluated and provided by the charging station 3 are transmitted to the central unit 2 in step S9, where they are evaluated by means of the trained aging state model in order to obtain the corresponding aging state. The operating characteristics can include one or more of the following characteristics: the preliminary aging state, which is ascertained in the charging station and is associated with the capacitance and/or the resistance change, the ambient temperature during the charging process, the battery static voltage at the predetermined charging state, the battery temperature during the charging process, the measurement variables and/or state variables that can be obtained by the battery management system of the specific battery type, and the differential capacitance calculated on the basis of the smoothed dQ/dU, in particular for the local extremum.
The aging state model in the central unit 2 can be trained beforehand on the basis of a training data set, wherein the aging state in the training data set is ascertained as a label in a controlled manner, for example on a workshop or test bench. The training data set assigns the corresponding aging state as a label to the set of operating characteristics. Alternatively, the aging state model can have PCA in order to narrow the feature space of the operating features.
In particular, the aging state model implemented in the central unit 2 is trained based on a plurality of vehicle batteries 41 of the same battery type, so that the aging state can thus be specified reliably.
For each aging state, an uncertainty or confidence can be calculated and assigned, which can be obtained directly from the gaussian process, in particular if a gaussian process model is used as the aging state model.
The aging state determined in the central unit 2 can be signaled in step S10 and in particular transmitted to the charging station 3, the user' S mobile device or the vehicle (the vehicle battery 41 of which is charged by the charging station 3) and displayed in a suitable manner. The aging state can also be transmitted in the form of a usage certificate to the user of the vehicle having the vehicle battery 41 in order to inform the user of important parameters of the vehicle battery and the estimated remaining service life or residual value of the vehicle battery.
Furthermore, the use of certificates may also indicate predictive maintenance plans or include abnormal warnings. For example, if there is a difference between the voltage measurement in a specific state of charge and the battery voltage according to the no-load voltage characteristic curve in an aged state determined by the aged state model, an abnormality can be determined.
The no-load voltage characteristic, which is dependent on the aging state, can be designed as a parameterized model or as a data-based model, which can be periodically modified or adjusted in the central unit 2 by parameterization or training based on the preliminary aging state of a plurality of vehicle batteries 41. The adjustment of the no-load voltage characteristic is carried out on the basis of a preliminary aging state determination, which is based on an evaluation of the no-load voltage characteristic. The parameterization of the no-load characteristic curve is then iteratively adjusted according to an optimization method until, for the vehicle battery measured at the charging station, the preliminary aging state determined on the basis of the iteratively adjusted no-load voltage characteristic curve corresponds as much as possible to the aging state determined in the central unit.
The parameters of the no-load voltage characteristic curve are transmitted to the charging station 3 after fitting or training, so that they can be used there for carrying out the method for ascertaining the preliminary aging state.

Claims (14)

1. A computer-implemented method for determining an aging state (SOH-C) of a device battery (41) in a technical device (4) by means of a power supply station (3), which is connected in communication with a central unit (2), the method having the following steps:
-performing (S5, S6) a discharging process or charging process of the device battery (41) from a first state of charge (SOC relax,1) to a second state of charge (SOC relax,2) by providing a charging current or discharging current by the power supply station (3);
-measuring (S3, S7) the battery static voltage in the power supply station (3), in particular in the rest state of the device battery (41), respectively in the first state of charge (SOC relax,1) and the second state of charge (SOC relax,2), and/or measuring the resistance gradient respectively in the first state of charge (SOC relax,1) and the second state of charge (SOC relax,2) with the application of stepped charging current edges, wherein the first state of charge and the second state of charge are determined in particular by a predetermined no-load voltage characteristic in dependence on the respective battery static voltage;
-ascertaining (S8) a preliminary ageing state in the power supply station (3) from measurements of the battery static voltage in the first and second states of charge or of the resistance gradient in the first and second states of charge;
-determining (S9) an ageing state in the central unit (2) by means of a data-based ageing state model depending on the preliminary ageing state and in particular at least one further operating characteristic, wherein the data-based ageing state model is designed for outputting an ageing state depending on the preliminary ageing state and in particular at least one further operating characteristic.
2. Method according to claim 1, wherein the no-load voltage characteristic is updated by determining parameters of the no-load voltage characteristic in order to ascertain the preliminary aging state, wherein the objective is to minimize a deviation between the preliminary aging state and the aging state ascertained in the central unit (2), wherein a data-based aging state model is retrained, in particular after each updating of the no-load voltage characteristic.
3. Method according to claim 1 or 2, wherein a first state of charge threshold corresponds to a preset state of charge threshold or a fully discharged state of the device battery (41), wherein it is determined that the first state of charge is reached when a respectively preset voltage limit is reached.
4. The method according to claim 1 or 2, wherein the second state of charge threshold corresponds to a pre-set state of charge threshold or a fully charged state of the device battery (41), wherein upon reaching an end of charge voltage it is determined that the second state of charge (SOC relax,2) is reached.
5. Method according to any one of claims 1 to 4, wherein the no-load voltage characteristic is designed as a probabilistic regression model or a parametric model, wherein model parameters of the no-load voltage characteristic are transmitted from the central unit (2) to the power supply station (3).
6. The method according to any one of claims 1 to 5, wherein a data-based aging state model is trained in the central unit (2) as a tag based on accurate measurements of the aging states of a plurality of device batteries (41).
7. Method according to claim 5 or 6, wherein one or more further state of charge thresholds are provided, wherein upon reaching a respective further state of charge threshold, the charging process or discharging process is interrupted and a battery static voltage, in particular in the rest state of the device battery (41), is measured, wherein the further state of charge with the respective battery static voltage is transmitted as a further operating characteristic to the central unit (2), whereupon the no-load voltage characteristic is trained repeatedly.
8. The method of any of claims 1 to 7, wherein the at least one additional operating characteristic comprises an ambient temperature during a charging process or a discharging process, a battery static voltage defined in a state of charge, a battery temperature defined in a state of charge, an extremum of a differential capacitance with respect to a battery voltage.
9. Method according to any of claims 1 to 8, wherein the device battery (41) is placed in a reproducible state, in particular at a battery temperature within a predetermined temperature range, before and during a discharging process or a charging process is performed on the device battery.
10. A method according to any one of claims 1 to 9, wherein the ageing status thus ascertained is used to ascertain remaining service life, in order to establish a use certificate for the associated device battery, the use certificate indicating the battery status.
11. The method according to any one of claims 1 to 10, wherein the data-based aging model comprises a data-based probability model, which in particular comprises at least one gaussian process model, wherein an uncertainty of the aging state ascertained by means of the aging state model is determined.
12. An apparatus for performing the method of any one of claims 1 to 11.
13. A computer program product comprising instructions which, when executed by at least one data processing apparatus, cause the data processing apparatus to perform the steps of the method according to any one of claims 1 to 11.
14. A machine readable storage medium comprising instructions which, when executed by at least one data processing apparatus, cause the data processing apparatus to perform the steps of the method according to any one of claims 1 to 11.
CN202311652671.1A 2022-11-17 2023-11-17 Method and device for determining the aging state of a device battery by means of a networked power supply station Pending CN118050641A (en)

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