Method for correcting available capacity of battery, battery management system and vehicle

Abstract

The invention relates to a method for correcting the available capacity of a battery, and the method comprises the steps: in the charging process of the battery, determining a characteristic collection moment t0 related to a capacity characteristic point of the battery based on the ratio dU / dQ of a collected battery voltage U to a collected battery capacity Q, the characteristic capacity Q0 corresponding to the capacity characteristic point of the battery is a fixed value irrelevant to the aging degree of the battery (S1); and calculating an accumulated charge amount [delta] Qc of the battery from the characteristic acquisition time t0, and correcting the available capacity Qk of the battery to the sum of the characteristic capacity Q0 and the accumulated charge amount [delta] Qc (S2). According to the method, the characteristic that the characteristic capacity Q0, corresponding to the capacity characteristic point, of the battery in each charging period is a fixed value irrelevant to the aging degree of the battery is fully utilized, the available capacity of the battery is corrected in a low-technical-cost and relatively-accurate mode, and a foundation is laid for accurately estimating the remaining endurance mileage of the vehicle.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for correcting the available capacity of a battery, a battery management system, a vehicle including a battery management system according to the present application, and a computer program product for at least assisting in implementing the steps of the method according to the present application. Background Art

[0002] During battery use, battery capacity estimation is a key function of the battery management system. It is of great significance for monitoring battery status, especially battery life. Common battery capacity estimation methods currently used include: the ampere-hour integration method, which has low estimation accuracy and is affected by battery aging; the open-circuit voltage method, which has strict requirements for test conditions, such as requiring the battery to be fully charged and left for a sufficient period of time before testing, and estimation accuracy is affected by battery aging; the neural network method, which requires a large amount of experimental data to train the neural network model and has high computing power requirements; the Kalman filter method, which also requires a high-performance processor to establish an accurate battery model, and the cell parameters on which the battery model is based are affected by numerous influencing factors.

[0003] Therefore, there is room for improvement in the current battery capacity estimation method. Summary of the Invention

[0004] The object of the present application is to provide a method for correcting the available capacity of a battery, a battery management system, a vehicle including the battery management system according to the present application, and a computer program product, so as to at least partially solve the problems in the prior art.

[0005] According to a first aspect of the present application, there is provided a method for correcting the available capacity of a battery, the method comprising:

[0006] - During the battery charging process, a characteristic collection time t0 associated with a capacity characteristic point of the battery can be determined based on a ratio dU / dQ of the collected battery voltage U to the battery capacity Q, wherein the characteristic capacity Q0 of the battery corresponding to the capacity characteristic point is a fixed value that is independent of the degree of battery aging; and

[0007] - The cumulative charge amount ΔQ of the battery from the feature collection time t0 can be calculated c and the available capacity of the battery Q k Corrected to the characteristic capacity Q0 and the cumulative charge amount ΔQ c sum.

[0008] The core concept of this application is to quickly determine the capacity characteristic point of the battery and its characteristic acquisition time by utilizing the characteristic that the ratio dU / dQ of the battery voltage U to the battery capacity Q reaches a local maximum at the characteristic capacity point, and to make full use of the characteristic that the characteristic capacity Q0 corresponding to the capacity characteristic point in each charging cycle is a fixed value that is independent of the degree of battery aging. c The available capacity of the battery Q k The correction is made, thereby correcting the battery's available capacity in a relatively low-tech and accurate manner, laying the foundation for accurately estimating the vehicle's remaining range.

[0009] According to an optional embodiment of the present application, during the charging process of the battery, when the battery state of charge is within a predetermined state of charge range of, for example, 30% to 90%, the collection time corresponding to the maximum ratio dU / dQ can be determined based on the time variation process of the ratio dU / dQ of the collected battery voltage U to the battery capacity Q as the characteristic collection time t0 related to the capacity characteristic point of the battery.

[0010] According to another optional embodiment of the present application, during the battery charging process, when the battery state of charge is within a predetermined state of charge range, the ratio dU / dQ of the collected battery voltage U to the battery capacity Q can be calculated at predetermined time intervals. If the calculated ratio dU / dQ is greater than a predetermined ratio threshold, the maximum ratio dU / dQ and the corresponding collection time are updated and recorded over time. If the recorded maximum ratio dU / dQ does not change after a predetermined number of calculations, the first collection time corresponding to the recorded maximum ratio dU / dQ is determined as the characteristic collection time t0 associated with the battery's capacity characteristic point.

[0011] According to another optional embodiment of the present application, the method may further include:

[0012] -During the battery discharge process, the battery can be discharged based on the accumulated ΔQ d and the corrected available capacity Q of the battery k Calculate the remaining capacity Q of the battery r , and at least based on the remaining capacity Q r The remaining range of vehicle 1 is estimated.

[0013] According to another optional embodiment of the present application, the battery capacity Q can be obtained by the ampere-hour integration method based on the change process of the battery current I collected over time starting from the charging time of the battery.

[0014] According to another optional embodiment of the present application, the cumulative charge capacity ΔQ of the battery from the characteristic acquisition time t0 can be obtained by the ampere-hour integration method based on the change process of the collected battery current I over time. c .

[0015] According to another optional embodiment of the present application, the cumulative discharge capacity ΔQ of the battery can be calculated based on the change of the collected battery current I over time from the discharge moment of the battery by the ampere-hour integration method. d and the remaining capacity of the battery Q r Calculated as the corrected available capacity Q of the battery k and the battery's cumulative discharge ΔQ d difference.

[0016] According to another optional embodiment of the present application, the battery may include, for example, a lithium iron phosphate battery.

[0017] According to another optional embodiment of the present application, the capacity characteristic point includes, for example, an intermediate capacity characteristic point.

[0018] According to another optional embodiment of the present application, the remaining capacity Q of the battery can be r , vehicle operating parameters, road condition information and battery status parameters, for example, estimate the remaining cruising range of the vehicle through a deep learning model, wherein the battery status parameters, for example, include the collected battery voltage U, battery current I, open circuit voltage V and / or internal resistance R, etc., the vehicle operating parameters, for example, include the collected data and / or historical data of vehicle speed, and / or the collected data and / or historical data of vehicle acceleration, etc., and the road condition information, for example, includes the road type of the planned driving route, road congestion conditions and / or road slope information, etc.

[0019] According to a second aspect of the present application, a battery management system is provided, wherein the battery management system may include the following components:

[0020] - a data acquisition unit configured to acquire battery status parameters; and

[0021] - A control unit configured to carry out the method according to the present application.

[0022] According to another optional embodiment of the present application, the data acquisition unit may also be configured to collect vehicle operating parameters and / or road condition information.

[0023] According to a third aspect of the present application, a vehicle is provided, comprising a battery management system according to the present application.

[0024] According to a fourth aspect of the present application, a computer program product, such as a computer-readable program carrier, is provided, which contains or stores computer program instructions, and when the computer program instructions are executed by a processor, at least assists in implementing the steps of the method described in the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The principles, features and advantages of the present invention will be better understood by describing the present invention in more detail below with reference to the accompanying drawings.

[0026] Figure 1 A flowchart showing a method for correcting the available capacity of a battery according to an exemplary embodiment of the present application;

[0027] Figure 2 A graph showing battery open circuit voltage versus battery capacity at different battery aging levels according to an exemplary embodiment of the present application is shown;

[0028] Figure 3 A graph showing a change process of the recorded ratio dU / dQ with respect to the battery state of charge according to an exemplary embodiment of the present application;

[0029] Figure 4 A flowchart showing a method for correcting the available capacity of a battery according to another exemplary embodiment of the present application is shown;

[0030] Figure 5 A schematic block diagram showing a battery management system according to an exemplary embodiment of the present application; and

[0031] Figure 6 A schematic diagram of a vehicle according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by this application more clearly understood, this application will be further described in detail below with reference to the accompanying drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the scope of protection of this application.

[0033] Figure 1 A flowchart of a method for correcting the available capacity of a battery according to an exemplary embodiment of the present application is shown. The following exemplary embodiments describe the method according to the present application in more detail.

[0034] like Figure 1As shown, the method may include steps S1 and S2. In step S1, during the charging process of the battery, the characteristic acquisition time t0 related to the capacity characteristic point of the battery can be determined based on the ratio dU / dQ of the collected battery voltage U to the battery capacity Q, wherein the characteristic capacity Q0 of the battery corresponding to the capacity characteristic point is a fixed value that is independent of the degree of aging of the battery. In the current embodiment of the present application, the battery is particularly a lithium iron phosphate battery. According to the unique aging mechanism of the lithium iron phosphate battery, the characteristic capacity Q0 of the battery corresponding to the capacity characteristic point remains almost unchanged during the battery aging process and is a fixed value that is independent of the degree of aging of the battery.

[0035] like Figure 2 A graph showing battery open circuit voltage (V) versus battery capacity (Q) at different battery aging levels according to an exemplary embodiment of the present application is shown. The first intersection of the first VQ curve (marked by a dashed line) and the vertical dotted line for a battery with a state of health (SOH) of 100%, the second intersection of the second VQ curve (marked by a solid line) and the vertical dotted line for a battery with a state of health (SOH) of 90%, and the third intersection of the third VQ curve (marked by a dashed line) and the vertical dotted line for a battery with a state of health (SOH) of 80% are all capacity characteristic points. The characteristic capacities (Q0) corresponding to these capacity characteristic points are all equal (e.g., 50 Ah), roughly equal to half of the total rated capacity of the battery, and are therefore referred to as "intermediate capacity characteristic points." Furthermore, a corresponding "low capacity characteristic point" may exist when the battery is at a lower state of charge (e.g., below 30%), and a corresponding "high capacity characteristic point" may exist when the battery is at a higher state of charge (e.g., above 90%).

[0036] In particular, a constant current charging method (i.e., the charging current remains substantially constant) can be used to charge the battery. During the charging process, the battery voltage U and battery capacity Q are acquired by the data acquisition unit 11. The battery capacity Q is determined based on the acquired temporal variation of the battery current I from the time of charging the battery using the ampere-hour integration method. To eliminate interference from "low-capacity characteristic points" and "high-capacity characteristic points," the ratio dU / dQ of the acquired battery voltage U to the battery capacity Q is calculated at predetermined time intervals only when the battery state of charge is within a predetermined state of charge range, e.g., 30% to 90%. The temporal variation of the ratio dU / dQ is recorded. For example, if a battery voltage of 3.2V and a battery capacity of 5Ah are acquired at time t1, and a battery voltage of 3.3V and a battery capacity of 5.1Ah are acquired at time t2, the ratio dU / dQ at time t2 can be calculated as follows:

[0037] dU / dQ=(3.3V–3.2V) / (5.1Ah–5Ah)=1V / Ah.

[0038] Considering that the charging current I remains basically unchanged, the battery internal resistance R can also be considered constant during a charging cycle. The battery voltage U is equal to the battery open circuit voltage V minus the voltage drop across the internal resistance. Therefore, during a charging cycle, the difference between the battery voltage U and the battery open circuit voltage V is always a fixed value I*R. Figure 3 A curve diagram showing the change process of the recorded ratio dU / dQ with respect to the battery state of charge SOC according to an exemplary embodiment of the present application is shown. When the battery state of charge is within a predetermined state of charge range of, for example, 30% to 90%, the ratio dU / dQ reaches a local maximum at the intermediate capacity characteristic point, which corresponds to the characteristic capacity Q0. Based on the change process of the recorded ratio dU / dQ with respect to time, the acquisition time corresponding to the maximum ratio dU / dQ can be determined as the characteristic acquisition time t0 related to the capacity characteristic point of the battery.

[0039] In order to improve data processing efficiency, when the calculated ratio dU / dQ is greater than a predetermined ratio threshold (for example, 6mV / Ah), the maximum ratio dU / dQ and the corresponding collection time can be updated and recorded over time. When the recorded maximum ratio dU / dQ does not change after exceeding a predetermined number of calculations, the first collection time corresponding to the recorded maximum ratio dU / dQ is determined as the characteristic collection time t0 related to the capacity characteristic point of the battery, thereby greatly reducing the amount of data to be recorded.

[0040] In step S2, the cumulative charge capacity ΔQ of the battery from the feature collection time t0 can be obtained. c and the available capacity of the battery Q k Corrected to the characteristic capacity Q0 and the cumulative charge amount ΔQ c Here, the cumulative charge amount ΔQ of the battery from the characteristic acquisition time t0 to the end of charging can be obtained based on the change process of the acquired battery current I over time, for example, by the ampere-hour integration method. c ——For example, 10Ah, so at the end of charging the battery’s available capacity Q k Corrected to the characteristic capacity Q0 and the cumulative charge amount ΔQ c The sum of

[0041] Q k =Q0+ΔQ c =50Ah+10Ah=60Ah.

[0042] According to the embodiment of the present application, the battery capacity characteristic point and its characteristic collection time can be quickly determined by utilizing the characteristic that the ratio dU / dQ of the battery voltage U to the battery capacity Q reaches a local maximum at the characteristic capacity point, and making full use of the characteristic that the characteristic capacity Q0 corresponding to the capacity characteristic point in each charging cycle is a fixed value that is independent of the degree of battery aging. With the help of the characteristic capacity Q0 and the cumulative charge amount ΔQ from the characteristic collection time t0, the battery capacity characteristic point and its characteristic collection time can be quickly determined. c The available capacity of the battery Q k The correction is made, thereby correcting the battery's available capacity in a relatively low-tech and accurate manner, laying the foundation for accurately estimating the vehicle's remaining range.

[0043] Figure 4 FIG1 shows a flowchart of a method for correcting the available capacity of a battery according to another exemplary embodiment of the present application. Figure 1 The differences between the embodiments shown in FIG and FIG are omitted, and the same steps are not described again for the sake of brevity.

[0044] like Figure 4 As shown, the method may further include step S3. In step S3, during the battery discharge process, the battery may be discharged based on the accumulated discharge ΔQ d and the corrected available capacity Q of the battery k Calculate the remaining capacity Q of the battery r , and at least based on the remaining capacity Q r Estimate the remaining cruising range of the vehicle 1. From the moment of battery discharge, the cumulative discharge capacity ΔQ of the battery can be calculated based on the collected battery current I over time using the ampere-hour integration method. d and the remaining capacity of the battery Q r Calculated as the corrected available capacity Q of the battery k and the battery's cumulative discharge ΔQ d difference.

[0045] Next, the remaining capacity Q of the battery can be r , vehicle operating parameters, road condition information and battery status parameters, etc. The battery status parameters may include, for example, the collected battery voltage U, battery current I, open circuit voltage V and / or internal resistance R, etc. In particular, the remaining capacity Q of the battery can be determined based on the open circuit voltage V and internal resistance R of the battery. rConvertible residual energy. The vehicle operating parameters may include, for example, collected data and / or historical data of vehicle speed, and / or collected data and / or historical data of vehicle acceleration, etc., which can reflect the user's driving habits and current driving status; the road condition information may include, for example, the type of road (highway, expressway, rural road, etc.) of the planned driving route, road congestion conditions, road slope information, etc., which may be obtained, for example, from an on-board navigation device. Based on the vehicle operating parameters and road condition information, the energy consumption of vehicle 1 in the future journey can be predicted, and thus the remaining cruising range of vehicle 1 can be predicted based on the estimated residual energy and the predicted energy consumption conditions.

[0046] Considering that there are many factors affecting the remaining cruising range and the relationship is complex, it can be based on the remaining capacity Q of the battery. r , vehicle operating parameters, road condition information and battery status parameters are used to estimate the remaining range of vehicle 1 through a deep learning model, wherein the deep learning model includes, for example, a feedforward neural network, a convolutional neural network, a recurrent neural network and / or a large language model based on Transformer.

[0047] According to the current embodiment of the present application, the characteristics of the battery capacity feature points can be used to estimate the remaining cruising range of the vehicle in a relatively accurate manner with low technical overhead when the specific capacity of the battery is unknown.

[0048] In addition, it should be noted that the step numbers described herein do not necessarily represent a chronological order, but are merely a reference mark. The order can be changed according to specific circumstances as long as the technical purpose of this application can be achieved.

[0049] Figure 5 A schematic block diagram of a battery management system according to an exemplary embodiment of the present application is shown.

[0050] like Figure 5 As shown, the battery management system 10 may include the following components:

[0051] - a data acquisition unit 11, which is configured to acquire battery status parameters, such as the acquired battery voltage U, battery current I, open circuit voltage V and / or internal resistance R; and

[0052] A control unit 12 configured to carry out the method according to the present application.

[0053] Optionally, the data acquisition unit 11 may also be configured to acquire vehicle operating parameters, which may include, for example, acquired data and / or historical data of vehicle speed, and / or acquired data and / or historical data of vehicle acceleration.

[0054] Optionally, the data collection unit 11 may be further configured to collect road condition information, for example, from a vehicle-mounted navigation device. The road condition information may include, for example, the road type of the planned driving route, road congestion conditions, and / or road slope information.

[0055] Figure 6 A schematic diagram of a vehicle 1 according to an exemplary embodiment of the present application is shown. The vehicle 1 may include a battery management system 10 according to the present application.

[0056] It should be understood that, in this document, the expressions "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance, nor should they be understood as implicitly indicating the quantity of the indicated technical features.

[0057] If an embodiment includes an "and / or" relationship between a first feature and a second feature, it should be interpreted as follows: according to one embodiment, the embodiment has both the first feature and the second feature, and according to another embodiment, the embodiment has either only the first feature or only the second feature.

[0058] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when only a single embodiment is described with respect to specific features. The feature examples provided in the present disclosure are intended to be illustrative and not limiting, unless otherwise stated. In specific implementations, multiple features may be combined with each other, depending on actual needs, where technically feasible. Various substitutions, changes, and modifications may be contemplated without departing from the spirit and scope of the present application.

Claims

1. A method for correcting the available capacity of a battery, the method comprising: During the charging process of the battery, a characteristic collection time t0 associated with a capacity characteristic point of the battery is determined based on a ratio dU / dQ of the collected battery voltage U to the battery capacity Q, wherein the characteristic capacity Q0 of the battery corresponding to the capacity characteristic point is a fixed value that is independent of the degree of aging of the battery; and Calculate the cumulative charge capacity ΔQ of the battery from the feature acquisition time t0 c and the available capacity of the battery Q k Corrected to the characteristic capacity Q0 and the cumulative charge amount ΔQ c sum.

2. The method according to claim 1, wherein During the charging process of the battery, when the battery state of charge is within a predetermined state of charge range, for example, 30% to 90%, the acquisition time corresponding to the maximum ratio dU / dQ is determined based on the time variation of the ratio dU / dQ of the acquired battery voltage U to the battery capacity Q as the characteristic acquisition time t0 related to the capacity characteristic point of the battery.

3. A method according to any one of the preceding claims, wherein During the battery charging process, when the battery state of charge is within a predetermined state of charge range, the ratio dU / dQ of the collected battery voltage U to the battery capacity Q is calculated at predetermined time intervals, and when the calculated ratio dU / dQ is greater than a predetermined ratio threshold, the maximum ratio dU / dQ and the corresponding collection time are updated and recorded over time. If the recorded maximum ratio dU / dQ does not change for more than a predetermined number of calculations, the first collection time corresponding to the recorded maximum ratio dU / dQ is determined as the characteristic collection time t0 related to the capacity characteristic point of the battery.

4. A method according to any one of the preceding claims, wherein: The method further comprises: During the battery discharge process, based on the battery cumulative discharge ΔQ d and the corrected available capacity Q of the battery k Calculate the remaining capacity Q of the battery r , and at least based on the remaining capacity Q r Estimate the remaining range of the vehicle (1).

5. A method according to any one of the preceding claims, wherein: From the moment of battery charging, the battery capacity Q is calculated based on the acquired battery current I’s change over time using the ampere-hour integration method. and / or Based on the change of the collected battery current I over time, the cumulative charge capacity ΔQ of the battery from the characteristic collection time t0 is calculated by the ampere-hour integration method. c ; From the moment of battery discharge, the cumulative discharge capacity ΔQ of the battery is calculated based on the change of the collected battery current I over time using the ampere-hour integration method d and the remaining capacity of the battery Q r Calculated as the corrected available capacity Q of the battery k and the battery's cumulative discharge ΔQ d and / or The battery comprises a lithium iron phosphate battery; and / or The capacity characteristic points include intermediate capacity characteristic points.

6. A method according to any one of the preceding claims, wherein: Based on the remaining capacity Q of the battery r , vehicle operating parameters, road condition information and battery status parameters, for example, estimating the remaining cruising range of the vehicle (1) through a deep learning model, wherein the battery status parameters include, for example, the collected battery voltage U, battery current I, open circuit voltage V and / or internal resistance R, the vehicle operating parameters include, for example, collected data and / or historical data of vehicle speed, and / or collected data and / or historical data of vehicle acceleration, and the road condition information includes, for example, the road type of the planned driving route, road congestion conditions and / or road slope information.

7. A battery management system (10), wherein: The battery management system (10) comprises the following components: A data acquisition unit (11) configured to acquire battery status parameters; and A control unit (12) configured to execute the method according to any one of claims 1 to 6.

8. The battery management system (10) according to claim 7, wherein: The data acquisition unit (11) is also configured to acquire vehicle operating parameters and / or road condition information.

9. A vehicle (1), comprising a battery management system (10) according to claim 7 or 8. 10 . A computer program product, such as a computer-readable program carrier, comprising or storing computer program instructions, which, when executed by a processor, at least assist in implementing the steps of the method according to claim 1 .

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