Electrical energy storage unit and method for operating an electrical energy storage unit and device

Abstract

A method for operating an electrical energy storage unit is described, the method comprising the steps of: a) checking at least one predefined first condition, the predefined first condition being indicative of a usage of the electrical energy storage unit and / or an accuracy of a mathematical model of the electrical energy storage unit; b) in case the at least one predefined first condition is fulfilled, determining at least one value of a parameter of the mathematical model and modifying the at least one value of the parameter in the mathematical model; c) operating the electrical energy storage unit with the modified mathematical model. A corresponding device, computer program, storage medium and electrical energy storage system are also described.

Description

Technical Field

[0001] The present invention provides a method for operating an electric energy storage unit, as well as a corresponding device, a corresponding computer program, a corresponding machine-readable storage medium, and a corresponding unit. Background Technology

[0002] With increasing electrification, especially of motor vehicles, electric energy storage units are becoming increasingly important. There are different levels of electrification. For example, there are vehicles that are purely electric and vehicles with internal combustion engines, where the electric motor only sometimes drives the vehicle or assists the engine. These different implementations of electrification typically involve different voltage levels and different designs for the electric energy storage units used.

[0003] Here, all implementations share a common feature: the energy storage units used are subject to aging effects, manifested, for example, by changes in the internal resistance of the energy storage units. Therefore, the internal resistance value of the energy storage unit recorded at a predetermined time point (which, for example, characterizes the energy storage unit's properties immediately after its manufacture or before it is actually used as an energy storage device) becomes meaningless after a certain period. Furthermore, differences exist between energy storage units due to manufacturing processes, manifested in their varying resistance values. While these differences are mostly not particularly pronounced, they can still affect the operational capability of the corresponding energy storage systems using these units. This can lead to problems in predicting the available power from the energy storage unit when it is overestimated, and can prevent timely replacement of the energy storage unit when it is considered functional or sufficiently functional despite defying the actual conditions of the system.

[0004] Publication US 2018 / 0143257 describes a method for determining parameter values ​​for a battery pack model that mathematically describes the battery pack.

[0005] Publication CN 102520361 describes a method for determining the aging coefficient, wherein the internal resistance of the battery pack is determined. Summary of the Invention

[0006] Advantages of the present invention

[0007] A method having the features according to the present invention is disclosed.

[0008] Here, in the method for operating an electric energy storage unit, at least one predefined first condition is checked, which represents the use of the electric energy storage unit and / or the accuracy of the mathematical model of the electric energy storage unit. In particular, the use of the electric energy storage unit can be described, for example, by its state of charge, its age, or its temperature. The accuracy of the mathematical model of the electric energy storage unit can be determined, for example, by comparing it with corresponding measurements, such as voltage measurements. The mathematical model can be stored, for example, in a data memory. The mathematical model can include, for example, differential equations, difference equations, or algebraic equations. Furthermore, a comprehensive characteristic curve based on data can also be a component of the mathematical model.

[0009] If the predefined first condition is met, at least one value for the parameter of the mathematical model is determined, and then that parameter value is modified within the mathematical model. This adapts the mathematical model to the modified characteristics of the energy storage unit, which may be derived, for example, due to aging effects.

[0010] Next, the energy storage unit is operated using the modified mathematical model. This includes, for example, determining the state of charge and predicting the available power, which is typically performed on the electronic control unit using the mathematical model.

[0011] Therefore, it is advantageously guaranteed that the mathematical model is only modified if at least one condition is met, thereby improving the accuracy in determining the parameter value and additionally achieving robustness, that is, insensitivity to model errors relative to the mathematical model and to external influences, such as temperature effects. This improves the quality of the determined parameter values ​​and allows for better and safer operation of the energy storage system. It can also extend the lifespan of the energy storage unit.

[0012] Other advantageous embodiments of the invention are the subject of the following description.

[0013] Suitablely, a current parameter is determined, representing the current flowing into or out of the energy storage unit. Additionally, a first voltage parameter is determined, representing the voltage present between the two terminals of the energy storage unit. Both can be implemented using corresponding sensors.

[0014] Furthermore, a second voltage parameter is determined, representing the voltage and derived from a mathematical model of the energy storage unit. Here, a determined current parameter is applied to the mathematical model to provide the second voltage parameter as an output parameter. The mathematical model includes a resistance parameter representing the resistance of the energy storage unit, and this resistance parameter is assigned a predetermined value. The value of this resistance parameter may be temperature-dependent, particularly depending on the temperature of the energy storage unit. This is advantageous because it allows for the determination of the accuracy of the mathematical model in a simple manner, for example.

[0015] Suitablely, the first voltage parameter and / or the second voltage parameter are filtered. This is advantageous because it reduces the influence of interfering frequencies, such as those caused by high-frequency noise, which significantly improves the quality of the determined resistance parameter values. For example, it is conceivable to use a bandpass filter, through which a targeted range of frequencies is filtered out and only the relevant frequency components remain in the voltage parameters, for example, to filter out the DC voltage components.

[0016] Suitably, the state of charge of the energy storage unit is determined, wherein the state of charge represents the use of the energy storage unit. This is advantageous because at least one parameter can have a small correlation with the state of charge within a predetermined range of the state of charge that can be checked by the predetermined first condition, and therefore can be determined more precisely within that range, since the at least one parameter is insensitive to changes in the state of charge.

[0017] Suitably, the temperature of the electric energy storage unit is determined, wherein the temperature represents the use of the electric energy storage unit. This is advantageous because the at least one parameter can have a small correlation with the temperature of the maxim within a predetermined range of temperatures that can be examined by the predetermined first condition, and therefore can be accurately determined within that range, since the at least one parameter is insensitive to changes in temperature.

[0018] Suitablely, the age of the energy storage unit is determined, whereby the age represents the usage of the energy storage unit. This age can be determined, for example, by the time since the energy storage unit was manufactured or by the time since the energy storage unit was integrated into a larger energy storage system. This is advantageous because it allows us to ascertain whether the energy storage unit is still at the beginning of its lifespan. Since the operation of the energy storage unit largely relies on the average values ​​of the parameters of the mathematical model, but these average values ​​can easily deviate from the actual values ​​of the relevant energy storage unit, it is advantageous to make corresponding corrections at the beginning of the energy storage unit's lifespan. Therefore, advantageously, aging effects affecting the parameter values ​​can be reliably ignored. This improves the accuracy of the mathematical model, thus contributing to the safe operation of the energy storage unit as its service life increases.

[0019] Suitablely, the accuracy of the mathematical model is determined, for example, by comparing model values ​​with measured values, such as voltage values. This is advantageous because it ensures that the mathematical model accurately reproduces the true characteristics of the energy storage unit. Alternatively or additionally, the model error of the mathematical model, that is, whether the numerical deviation between the model values ​​and the measured values ​​has reached a convergence state, can be checked. The convergence state can be checked, for example, by checking whether the numerical deviation between the model values ​​and the measured values ​​has not exceeded a predetermined limit within a predefined time period prior to the current point in time, such as one minute.

[0020] Suitably, when the use is represented by the state of charge, the predefined first condition includes a state of charge value in the range of 30% to 80%, particularly from 40% to 70%. Depending on the type of energy storage unit, within this range of state of charge, one or more parameters of the mathematical model have a small correlation with the state of charge, which facilitates and improves the determination of more accurate parameter values.

[0021] Suitably, when the use is represented by the temperature of the electric energy storage unit, the predefined first condition includes a temperature value exceeding 20°C, and especially exceeding 30°C. Depending on the type of electric energy storage unit, within this temperature range, one or more parameters of the mathematical model show minimal correlation with temperature, which facilitates and improves the determination of more accurate parameter values.

[0022] Suitablely, when the use is represented by the age of the energy storage unit, the predefined first condition includes an age value of less than 180 days, especially less than 90 days. This is advantageous because the aging effect of the battery pack can be ignored, which makes it easier and better to determine more accurate parameter values.

[0023] Suitablely, when representing the accuracy of the mathematical model of the energy storage unit, the predefined first condition includes a numerical deviation of less than 20 mV, particularly less than 10 mV, between the mathematical model and the measured value. This first condition may also include checking whether the model error of the mathematical model has reached a convergence state, that is, whether it has converged towards a fixed value. This is advantageous in order to evaluate the accuracy of the mathematical model, which facilitates and improves the determination of more accurate parameter values.

[0024] Suitablely, to determine the current parameters, current measurement data of the energy storage unit is detected using a current sensor; and / or to determine the first voltage parameter, voltage measurement data of the energy storage unit is detected using a voltage sensor. This is advantageous because the aforementioned filtering operations can be integrated into the corresponding sensors, and therefore a less expensive implementation of the method exists.

[0025] The subject of this disclosure is also an apparatus for operating an electric energy storage unit, comprising at least one device configured to implement all steps of the disclosed method. This at least one device may, for example, include a battery pack management control device and corresponding power electronics, such as an inverter, as well as current sensors and / or voltage sensors and / or temperature sensors. An electronic control unit, particularly an electronic control unit implemented as a battery pack management control device, can also be such a device. The electronic control unit can be particularly understood as an electronic control device, which includes, for example, a microcontroller and / or a dedicated hardware module, such as an ASIC, but a computer or a memory programmable controller can also fall into this category. Therefore, the aforementioned advantages can be achieved.

[0026] The subject of this disclosure is also a computer program comprising instructions that cause the disclosed device to perform all the steps of the disclosed method. Therefore, the aforementioned advantages can be achieved.

[0027] The subject of this disclosure is also a machine-readable storage medium on which a disclosed computer program is stored. Thus, the aforementioned advantages can be achieved.

[0028] The subject of this disclosure is also an electric energy storage system comprising at least one electric energy storage unit and the disclosed device. Therefore, the aforementioned advantages can be achieved. The electric energy storage unit can be particularly understood as an electrochemical battery pack and / or a battery pack module having at least one electrochemical battery pack and / or a battery pack having at least one battery pack module. For example, the electric energy storage unit can be a lithium-based battery pack, a lithium-based battery pack module, or a lithium-based battery pack. The electric energy storage unit can particularly be a lithium-ion battery pack, a lithium-ion battery pack module, or a lithium-ion battery pack. Furthermore, the type of battery pack can be a lithium-polymer battery, a nickel-metal oxide battery, a lead-acid battery, a lithium-air battery, or a lithium-sulfur battery, or very generally, a battery of any electrochemical composition. A capacitor may also serve as an electric energy storage unit. Attached Figure Description

[0029] Advantageous embodiments of the invention are shown in the accompanying drawings and will be further explained in the following description.

[0030] Figure 1 A flowchart of the disclosed method according to the first embodiment is shown;

[0031] Figure 2 A flowchart of the disclosed method according to the second embodiment is shown;

[0032] Figure 3 A schematic diagram of an electric energy storage system according to one embodiment is shown. Detailed Implementation

[0033] In all the accompanying drawings, the same reference numerals denote the same equipment parts or the same method steps.

[0034] Figure 1 A flowchart of the method for operating an electric energy storage unit according to the first embodiment is shown.

[0035] Here, in the first step S11, at least one predefined first condition is checked, which represents the use of the energy storage unit and / or the accuracy of the mathematical model of the energy storage unit. This at least one condition may, for example, include: a state of charge value within the range of 30% to 80%; and / or a temperature of at least 20°C, particularly at least 30°C; and / or an accuracy of the mathematical model of the energy storage unit that is at most 10mV numerically compared to the corresponding measurement value for voltage. Particularly preferably, all of the aforementioned exemplary conditions are met.

[0036] Assuming that at least one first condition is satisfied, in the second step S12, at least one value of the parameter of the mathematical model is determined and the determined at least one parameter value is used within the mathematical model, that is, the mathematical model or the parameterization of the mathematical model is modified accordingly using numerical values.

[0037] In the third step S13, the energy storage unit is operated using the modified mathematical model. This means, for example, that the method disclosed therein is implemented in the form of a computer, that is, an electronic control unit that operates as a computer program, using the modified parameter values. Therefore, control commands issued by the electronic control unit are based on the modified parameter values ​​when necessary. This is important, for example, for the power prediction of the energy storage unit in order to accurately depict the current performance of the energy storage unit.

[0038] Figure 2 A flowchart of the method for operating an electric energy storage unit according to the second embodiment is shown.

[0039] In the first step S21, a current parameter is determined, which represents the current flowing into or out of the energy storage unit. This can be achieved, for example, by means of measurement using a current sensor.

[0040] In the second step S22, a first voltage parameter is determined, which represents the voltage existing between the two terminals of the energy storage unit. This can be achieved, for example, by means of measurement using a voltage sensor.

[0041] In the third step S23, a second voltage parameter is determined. This second voltage parameter represents the voltage and is derived from a mathematical model of the energy storage unit, wherein a determined current parameter is applied to the mathematical model for this purpose. This means, for example, using the corresponding value of the current parameter as an input value to the mathematical model, and thereby deriving the corresponding voltage value as the output parameter of the mathematical model. Here, the mathematical model includes a resistance parameter representing the resistance of the energy storage unit, and this resistance parameter is assigned a predetermined value. This predetermined value may, for example, have been determined beforehand based on laboratory measurements.

[0042] Next, in step S24, the accuracy of the mathematical model is determined by comparing the first voltage parameter with the second voltage parameter. Alternatively or additionally, the state of charge of the energy storage unit and / or the temperature and / or age of the energy storage unit can also be determined. In step S25, the accuracy determined in this way is used to check whether the mathematical model meets the predetermined accuracy. Alternatively or additionally, the usage of the energy storage unit can be checked using the parameters mentioned above.

[0043] Assuming the check is successful and the pre-defined accuracy is met, in step S26, at least one value of the parameters of the mathematical model, particularly the value of the resistance parameter, is determined, and the parameter values ​​of the model or within the model are modified. This determination can be achieved, for example, by means of an observer, a structure known from control techniques, or a Kalman filter. It is also possible to use the least squares method to adapt the mathematical model as well as possible to the corresponding values ​​of the first voltage parameter by modifying the parameter values.

[0044] In the seventh step S27, the energy storage unit is operated using the modified mathematical model. This means, for example, that the method disclosed therein is implemented in a computer form, that is, an electronic control unit that operates as a computer program, using the modified parameter values. Therefore, control commands issued by the electronic control unit are based on the modified parameter values ​​when necessary. This is important, for example, for the power prediction of the energy storage unit in order to accurately depict the current performance of the energy storage unit.

[0045] Figure 3A schematic diagram of an electric energy storage system 30 according to one embodiment is shown. Here, the electric energy storage system 30 includes at least one electric energy storage unit (not shown here), a sensor 31, a device 32, and a power electronic component 33.

[0046] Here, device 32 can exchange data with connected sensors 31, such as voltage and current sensors. It is also possible to receive data from the connected sensors 31 in only one direction. Device 32 can also control connected power electronics 33 to, for example, comply with current limits. Power electronics 33 can be, for example, an inverter.

[0047] Here, device 32 includes, for example, an electronic control unit, which in Figure 3 Not shown separately. Device 32 may also include other electronic control units.

Claims

1. A method for operating an electric energy storage unit, the method comprising the following steps: a) Check at least one predefined first condition, said predefined first condition representing the use of the electric energy storage unit and / or the accuracy of the mathematical model of the electric energy storage unit, wherein, A current parameter is determined, representing the current flowing into or out of the energy storage unit. A first voltage parameter is determined, representing the voltage between the two terminals of the energy storage unit. A second voltage parameter is determined, representing the voltage and derived from a mathematical model of the energy storage unit. The determined current parameter is applied to the mathematical model, which includes a resistance parameter representing the resistance of the energy storage unit and assigned a predetermined value. The accuracy of the mathematical model is determined and / or the use of the energy storage unit is checked by comparing the first voltage parameter with the second voltage parameter. b) Determine the value of the resistance parameter of the mathematical model and modify the value of the resistance parameter in the mathematical model only if the at least one predefined first condition is met, wherein the determination is achieved by means of an observer, a structure known from control techniques, a Kalman filter, or the least squares method; c) The energy storage unit is operated using a modified mathematical model, wherein the modified values ​​of the resistance parameters are used to operate the energy storage unit. Wherein, when the use is represented by the state of charge, the predefined first condition includes a state of charge value in the range of 30% to 80%; and / or where, when the use is represented by the temperature of the energy storage unit, the predefined first condition includes a temperature value exceeding 20°C; and / or where, when the use is represented by the age of the energy storage unit, the predefined first condition includes an age value of less than 180 days; and / or where, when representing the accuracy of the mathematical model of the energy storage unit, the predefined first condition includes a numerical deviation of less than 20mV between the mathematical model and the measured value.

2. The method according to claim 1, wherein, When the use is indicated by the state of charge, the predefined first condition includes a state of charge value in the range of 40% to 70%.

3. The method according to claim 1, wherein, When the use is represented by the temperature of the energy storage unit, the predefined first condition includes a temperature value exceeding 30°C.

4. The method according to claim 1, wherein, When the use is represented by the age of the energy storage unit, the predefined first condition includes an age value of less than 90 days.

5. The method according to claim 1, wherein, In representing the accuracy of the mathematical model of the energy storage unit, the predefined first condition includes a numerical deviation of less than 10mV between the mathematical model and the measured value.

6. The method according to any one of claims 1 to 5, further comprising: g) Filter the first voltage parameter and / or the second voltage parameter.

7. The method according to claim 6, wherein, The first voltage parameter and / or the second voltage parameter are filtered by means of a bandpass filter.

8. The method according to any one of claims 1 to 5, further comprising: h) Determine the charging state of the energy storage unit, wherein the charging state indicates the use of the energy storage unit; And / or determine the temperature of the energy storage unit, wherein the temperature represents the use of the energy storage unit; and / or determine the age of the energy storage unit, wherein the age represents the use of the energy storage unit; and / or determine the accuracy of the mathematical model of the energy storage unit.

9. The method according to any one of claims 1 to 5, wherein, in order to determine the current parameter, current measurement data of the energy storage unit is detected by means of a current sensor; and / or, in order to determine the first voltage parameter, voltage measurement data of the energy storage unit is detected by means of a voltage sensor.

10. An apparatus (32) for operating an electric energy storage unit, the apparatus comprising at least one means configured to perform all the steps of the method according to any one of claims 1 to 9.

11. The apparatus (32) for operating an electric energy storage unit according to claim 10, wherein, The device is an electronic control unit.

12. A computer program product comprising a computer program including instructions that cause: the device (32) for operating an electric energy storage unit according to claim 10 or 11 to perform all the steps of the method according to any one of claims 1 to 9.

13. A machine-readable storage medium having a computer program stored thereon, the computer program comprising instructions that cause: the apparatus (32) for operating an electric energy storage unit according to claim 10 or 11 to perform all the steps of the method according to any one of claims 1 to 9.

14. An electric energy storage system (30) comprising at least one electric energy storage unit and a device (32) for operating the electric energy storage unit according to claim 10 or 11.

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