Battery detection method, energy storage system and electrification equipment

Abstract

The embodiment of the invention provides a battery detection method, an energy storage system and electrified equipment, and the method comprises the steps: obtaining a first impedance spectrum of a battery at a first frequency band; determining a characteristic frequency according to the first impedance spectrum, wherein the characteristic frequency changes along with the SOC of the battery; when the deviation condition of the characteristic frequency relative to the reference characteristic frequency meets a preset condition, acquiring a second impedance spectrum of the battery in a second frequency band; wherein the first frequency band is a subset of the second frequency band, and the reference characteristic frequency is the characteristic frequency of the impedance spectrum when the SOC of the battery is a preset value. The deviation condition of the characteristic frequency of the battery relative to the reference characteristic frequency is determined through small-frequency-band scanning, and large-frequency-band scanning is performed when the deviation condition meets the preset condition, so that the scanning frequency can be reduced, the scanning time is shortened, the detection efficiency and accuracy are improved, and the monitoring power consumption is reduced.

Description

Technical Field

[0001] This application relates to the technical field of energy storage, and particularly to a battery detection method and an energy storage system. Background Art

[0002] The electrochemical impedance spectroscopy (EIS) of a battery is a spectrum used to characterize the impedance of the battery. Estimating the state of charge (SOC) of a battery based on the impedance spectrum (EIS) is a non-destructive and high-precision technical means, which analyzes the dynamic impedance response of the battery at different frequencies and extracts characteristic parameters related to the SOC. In related technologies, each time the SOC of the battery is estimated, a full-frequency electrochemical impedance scan is required to generate a Nyquist plot of the electrochemical impedance. The full-frequency scan takes a long time and consumes high power, and there will be fluctuation errors when the scan time is long. Summary of the Invention

[0003] In view of the above problems, embodiments of this application provide a battery detection method, an energy storage system, and an electrified device to solve the above technical problems and achieve the purpose of improving the detection efficiency and reducing the detection power consumption.

[0004] In a first aspect, an embodiment of this application provides a battery detection method, including: obtaining a first impedance spectrum of a battery in a first frequency band; determining a characteristic frequency according to the first impedance spectrum, where the characteristic frequency changes with the SOC of the battery; when the deviation of the characteristic frequency from a reference characteristic frequency meets a preset condition, obtaining a second impedance spectrum of the battery in a second frequency band; where the first frequency band is a subset of the second frequency band, and the reference characteristic frequency is the characteristic frequency of the impedance spectrum when the SOC of the battery is a preset value. This embodiment determines the deviation of the characteristic frequency of the battery from the reference characteristic frequency through a small-frequency band scan, and performs a large-frequency band scan when the deviation meets the preset condition, which can reduce the scan frequency, thereby reducing the scan time, improving the detection efficiency and accuracy, and reducing the monitoring power consumption.

[0005] Second aspect, an embodiment of the present application provides a battery detection method, including: scanning the battery in a medium and low frequency band to obtain a first impedance spectrum; determining a characteristic frequency according to the first impedance spectrum, where the characteristic frequency varies with the state of charge (SOC) of the battery; when the deviation of the characteristic frequency relative to a reference characteristic frequency meets a preset condition, scanning the battery in a full frequency band to obtain a second impedance spectrum; the reference characteristic frequency is the characteristic frequency of the impedance spectrum when the SOC of the battery is a preset value; determining the SOC of the battery according to the second impedance spectrum; and generating an alarm signal when the SOC of the battery meets an alarm condition. By performing a small frequency band scan to determine the deviation of the characteristic frequency of the battery relative to the reference characteristic frequency, and performing a large frequency band scan when the deviation meets the preset condition, this embodiment can reduce the scanning frequency, thereby reducing the scanning time, improving the alarm detection efficiency and accuracy, and reducing the monitoring power consumption.

[0006] Third aspect, an embodiment of the present application provides an energy storage system, including a battery and a battery management system (BMS); the battery management system is configured to execute the battery detection method of the above embodiment.

[0007] Fourth aspect, an embodiment of the present application provides an electrified device, including a device main body and the energy storage system as described above provided on the device main body.

[0008] The battery detection method, energy storage system, and electrified device provided by the embodiments of the present application can determine the deviation of the characteristic frequency of the battery relative to the reference characteristic frequency through a small frequency band scan, and perform a large frequency band scan when the deviation meets the preset condition, which can reduce the scanning frequency, thereby reducing the scanning time, improving the detection efficiency and accuracy, and reducing the monitoring power consumption.

[0009] These aspects or other aspects of the present application will be more clearly understood in the following description of the embodiments. Description of the Drawings

[0010] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0011] Figure 1 A schematic diagram showing the application scenario of the embodiment of the present application is shown.

[0012] Figure 2 A flowchart showing the battery detection method provided by the embodiment of the present application is shown.

[0013] Figure 3The flowchart of another battery detection method provided by the embodiments of the present application is shown. Detailed implementation manners

[0014] The following details the implementation manners of the present application. The examples of the implementation manners are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The implementation manners described below with reference to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application.

[0015] To enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0016] In the embodiments of the present application, it should be noted that in this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0017] Moreover, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0018] In the description of the embodiments of the present application, words such as "example" or "for example" are used to indicate examples, explanations or descriptions. Any embodiment or design solution described as "for example" or "example" in the embodiments of the present application is not construed as being more preferred or having more advantages than another embodiment or design solution. The use of words such as "example" or "for example" is intended to present relative concepts in a clear manner.

[0019] In addition, "a plurality of" in the embodiments of the present application means two or more. In view of this, "a plurality of" in the embodiments of the present application can also be understood as "at least two". "At least one" can be understood as one or more, for example, it can be understood as one, two or more. For example, including at least one means including one, two or more, and it does not limit which ones are included. For example, including at least one of A, B, and C, then what can be included is A, B, C, A and B, A and C, B and C, or A, B, and C.

[0020] It should be noted that in the embodiments of the present application, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / ", unless otherwise specified, generally represents an "or" relationship between the front and rear associated objects.

[0021] It should be pointed out that "connection" in the embodiments of the present application can be understood as electrical connection, and the connection of two electrical components can be a direct or indirect connection between the two electrical components. For example, when A is connected to B, it can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0022] Please refer to Figure 1 , which shows a schematic diagram of an application scenario provided by the embodiments of the present application. This application scenario includes an electrified device 10. The electrified device 10 can be an energy storage device or an electrical device. For example, the electrified device 10 is a device such as an electric vehicle, an electric ship, or an electric aircraft. The electrified device 10 includes a battery management system (BMS) 101 and a battery module. For example Figure 1 As shown, the electrified device 10 includes an energy storage system, and this energy storage system includes a BMS 101 and this battery module. This battery module includes one or more batteries.

[0023] The BMS 101 is used to obtain the impedance spectrum of the battery and estimate the SOC of the battery based on the impedance spectrum of the battery. In an alternative embodiment, during the process of the BMS 101 obtaining the impedance spectrum of the target battery through impedance detection, the BMS 101 obtains the voltage across the target battery under the action of an excitation signal through a voltage detection device, the BMS 101 obtains the current passing through the target battery under the action of this excitation signal through a current detection device, the BMS 101 determines the impedance of the target battery according to the voltage across the target battery and the current passing through the target battery, and the BMS 101 determines the impedance spectrum of the target battery according to the impedance of the target battery determined under the action of excitation signals of different frequencies.

[0024] In the related art, each time the State of Charge (SOC) of a battery is estimated, an electrochemical impedance scan needs to be performed in the full frequency band to generate a Nyquist plot of the electrochemical impedance. The full frequency band scan has a long time and high power consumption, and there is a problem that the impedance has changed due to the long time period during the full frequency band scan, resulting in inaccurate results. Therefore, the embodiments of the present application provide a battery detection method, an energy storage system, and an electrified device to achieve the purpose of improving the detection efficiency and accuracy and reducing the detection power consumption. This battery detection method can be executed by Figure 1 the BMS 101 shown in

[0025] The battery detection method provided by the embodiments of the present application determines the deviation of the characteristic frequency of the battery relative to the reference characteristic frequency through a small frequency band scan. When the deviation satisfies a preset condition, a large frequency band scan is performed, which can reduce the scan frequency, thereby reducing the scan time, improving the detection efficiency and accuracy, and reducing the monitoring power consumption. Referring to Figure 2 shown, the battery detection method includes the following steps.

[0026] Step S201, obtain a first impedance spectrum of the battery in a first frequency band.

[0027] In the embodiments of the present application, the first frequency band includes characteristic frequencies that change with the SOC. In some embodiments, the first frequency band is located in the medium and low frequency bands. Among them, the typical frequency range of the medium frequency band (MF) is 10 Hz to 1 kHz. The typical frequency range of the low frequency band (LF) is 0.1 Hz to 10 Hz. The typical frequency range of the high frequency band (HF) is 1 kHz to 100 kHz.

[0028] Step S202, determine a characteristic frequency according to the first impedance spectrum, and this characteristic frequency changes with the SOC of the battery.

[0029] As an implementation manner, determining the characteristic frequency according to the first impedance spectrum includes: extracting the extreme value of the first impedance spectrum; determining the characteristic frequency based on the frequency corresponding to the extreme value. This characteristic frequency increases as the SOC decreases.

[0030] Step S203, when the deviation of the characteristic frequency relative to the reference characteristic frequency satisfies a preset condition, obtain a second impedance spectrum of the battery in a second frequency band.

[0031] Among them, the first frequency band is a subset of the second frequency band. The change in SOC will cause a change in the impedance spectrum. Especially in the middle and low frequency bands, the impedance performance and the change rate will change significantly. As an implementation, the first frequency band is located in the middle and low frequency bands. The low frequency band, middle frequency band, and high frequency band of the electrochemical impedance spectrum (EIS) respectively correspond to different physical and chemical processes inside the battery, and their response characteristics can reflect the kinetic behavior, interface characteristics, and material properties of the battery. As an implementation, the second frequency band is the full frequency band to obtain different physical and chemical processes inside the battery. The typical frequency range of the full frequency band is 0.1 Hz to 100 kHz.

[0032] The reference characteristic frequency is the characteristic frequency of the impedance spectrum when the SOC of the battery is a preset value. The reference characteristic frequency can be determined in advance. Specifically, it can be scanned when the SOC of the battery is a preset value to obtain the impedance spectrum, and the characteristic frequency is determined based on this impedance spectrum as the reference frequency. As an implementation, the extreme value of the impedance spectrum is extracted, and the characteristic frequency is determined based on the frequency corresponding to this extreme value. As an example, the frequency corresponding to the extreme value is used as the characteristic frequency.

[0033] In some implementations, the preset condition in step S203 is that the change in the characteristic frequency relative to the reference characteristic frequency is greater than a preset ratio. This preset ratio can be obtained based on statistics. Specifically, the characteristic frequencies under different SOCs can be statistically analyzed in advance, and the deviation of the characteristic frequencies under different SOCs relative to the reference characteristic frequency can be determined, and then this preset ratio can be set according to actual needs.

[0034] There is an inflection point in the variation of the above-mentioned characteristic frequency of the battery with the SOC. When the SOC is greater than this inflection point, the change of the characteristic frequency of the battery with the SOC is small, that is, the change of the characteristic frequency caused by the unit change of the SOC is small; when the SOC of the battery is less than this inflection point, the change of the characteristic frequency of the battery with the SOC is large, that is, the change of the characteristic frequency caused by the unit change of the SOC is large. This inflection point is usually a relatively small SOC. Exemplarily, in some batteries, the inflection point of the SOC of the battery is 25%. It should be understood that the aforementioned inflection point may vary in different batteries. In some embodiments, this preset value is determined based on the maximum value of the SOC. For example, it can be set near the maximum value of the SOC. The above preset ratio can be determined based on the deviation ratio of the reference characteristic frequency relative to the characteristic frequency at the inflection point. For example, the preset ratio is set to this deviation ratio. At this time, when the SOC is greater than this inflection point, the deviation of the characteristic frequency determined in step S202 relative to the reference characteristic frequency is less than this preset ratio; when the SOC is less than this inflection point, the deviation of the characteristic frequency determined in step S202 relative to the reference characteristic frequency is greater than this preset ratio. Since when the SOC is less than this inflection point, the change of the characteristic frequency caused by the unit change of the SOC is large, that is, once the SOC is less than this inflection point, a slight change in the SOC will cause the deviation of the characteristic frequency determined in step S202 relative to the reference characteristic frequency to be greater than this preset ratio. Thus, it can sensitively detect whether the SOC is less than this inflection point, that is, sensitively detect whether the SOC of the battery is a relatively small value, and realize the scanning of the second frequency band when the SOC is small.

[0035] An embodiment of the present application provides a battery detection method, which can generate an alarm signal when the SOC of the battery meets the alarm condition, and determine the deviation of the characteristic frequency of the battery relative to the reference characteristic frequency through small frequency band scanning. When this deviation meets the preset condition, large frequency band scanning is performed, which can reduce the scanning frequency, thereby reducing the scanning time, improving the alarm detection efficiency and reducing the monitoring power consumption. At the same time, it avoids the problem that the impedance has changed due to the long time period of full frequency band scanning, resulting in inaccurate results, and improves the accuracy. Refer to Figure 3 As shown, the method includes the following steps.

[0036] Step S301, scan the battery in the medium and low frequency bands to obtain a first impedance spectrum.

[0037] Step S302, determine the characteristic frequency according to the first impedance spectrum, and this characteristic frequency changes with the SOC of the battery.

[0038] As an implementation manner, determining the characteristic frequency according to the first impedance spectrum includes: extracting the extreme value of the first impedance spectrum; determining the characteristic frequency based on the frequency corresponding to this extreme value.

[0039] Step S303: When the deviation of the characteristic frequency relative to the reference characteristic frequency meets a preset condition, scan the battery over the full frequency band to obtain a second impedance spectrum. The reference frequency refers to the foregoing description in this specification and will not be elaborated here.

[0040] As an implementation, the preset condition in step S303 is that the change in the characteristic frequency relative to the reference characteristic frequency is greater than a preset ratio. This preset ratio can be obtained based on statistics. Specifically, the characteristic frequencies under different SOCs can be pre-statistically obtained, and the deviation of the characteristic frequencies under different SOCs relative to the reference characteristic frequency can be determined. Then, the preset ratio can be set according to actual needs.

[0041] Step S304: Determine the SOC of the battery according to the second impedance spectrum.

[0042] Referring to the prior art for determining the SOC of the battery based on the impedance spectrum over the full frequency band, this will not be elaborated in the embodiments of the present application.

[0043] Step S305: When the SOC of the battery meets the alarm condition, generate an alarm signal.

[0044] In the embodiments of the present application, an alarm signal is generated when the SOC of the battery is small, and the alarm condition may be that the SOC is less than the alarm threshold. This alarm threshold may be less than the inflection point of the aforementioned SOC. Exemplarily, in some batteries, the inflection point of the SOC of the battery is 25%, and the alarm threshold may be set to 20%. It should be understood that the aforementioned inflection point may vary in different batteries. The SOC corresponding to the reference characteristic frequency is determined based on the maximum value of the SOC. The above preset ratio may be determined based on the deviation ratio of the reference characteristic frequency from the characteristic frequency of the inflection point. For example, the preset ratio is set to this deviation ratio. At this time, when the SOC is greater than the inflection point, the deviation of the characteristic frequency determined in step S302 from the reference characteristic frequency is less than the preset ratio; when the SOC is less than the inflection point, the deviation of the characteristic frequency determined in step S302 from the reference characteristic frequency is greater than the preset ratio. Since when the SOC is less than the inflection point, the change in the characteristic frequency caused by a unit change in the SOC is relatively large, once the SOC is less than the inflection point, a slight change in the SOC will cause the deviation of the characteristic frequency determined in step S302 from the reference characteristic frequency to be greater than the preset ratio. Thus, it is possible to sensitively detect whether the SOC is less than the inflection point, that is, to sensitively detect whether the SOC of the battery is a small value. Thus, by scanning in the medium and low frequency bands, it is possible to determine whether the SOC is less than the inflection point, that is, to preliminarily determine that the SOC is a small value. Further, it can be determined whether the SOC meets the alarm condition through steps S303 to S305. In the aforementioned battery, the inflection point of the SOC of the battery is 25%, and the alarm threshold may be set to 20%. By scanning in the medium and low frequency bands, it is possible to determine that the SOC is less than 25%. At this time, a full-band scan of the battery is triggered to determine whether the SOC is lower than 20%. If it is lower than 20%, an alarm signal is generated.

[0045] An embodiment of the present application provides an energy storage system, including a battery and a battery management system (Battery Management System, BMS); the battery management system is used to execute the battery detection method of the above embodiment.

[0046] An embodiment of the present application provides an electrified device, including a device main body and the energy storage system as described above provided on the device main body.

[0047] The battery detection method, energy storage system and electrified device provided by the embodiments of the present application determine the deviation of the characteristic frequency of the battery from the reference characteristic frequency through small-band scanning. When the deviation meets the preset conditions, a large-band scan is performed, which can reduce the scanning frequency, thereby reducing the scanning time, improving the detection efficiency and accuracy, and reducing the monitoring power consumption.

[0048] The above are only the preferred embodiments of the present application and do not impose any formal restrictions on the present application. Although the present application has been disclosed above with the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present application. However, as long as it does not depart from the content of the technical solution of the present application, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A battery detection method, characterized in that, Including: Obtain a first impedance spectrum of the battery in a first frequency band; Determine a characteristic frequency according to the first impedance spectrum, where the characteristic frequency varies with the state of charge (SOC) of the battery; When the deviation of the characteristic frequency from a reference characteristic frequency satisfies a preset condition, obtain a second impedance spectrum of the battery in a second frequency band; Wherein, the first frequency band is a subset of the second frequency band, and the reference characteristic frequency is the characteristic frequency of the impedance spectrum when the SOC of the battery is a preset value.

2. The battery detection method according to claim 1, characterized in that After obtaining the second impedance spectrum of the battery in the second frequency band, it further includes: determining the SOC of the battery according to the second impedance spectrum.

3. The battery detection method according to claim 1, characterized in that The first frequency band is located in the medium and low frequency bands.

4. The battery detection method according to claim 1, wherein The second frequency band is the full frequency band.

5. The battery detection method according to claim 1, wherein Determining a characteristic frequency according to the first impedance spectrum includes: Extract the extreme values of the first impedance spectrum; Determine the characteristic frequency based on the frequencies corresponding to the extreme values.

6. The battery detection method according to any one of claims 1 to 5, characterized in that, The preset condition is that the change of the characteristic frequency relative to the reference characteristic frequency is greater than a preset ratio.

7. The battery detection method according to claim 6, wherein, The preset value is determined based on the maximum value of the SOC, and the preset ratio is determined based on the inflection point of the reference characteristic frequency with respect to the SOC of the battery. Wherein, when the SOC of the battery is greater than the inflection point, the characteristic frequency changes less with the SOC of the battery; when the SOC of the battery is less than the inflection point, the characteristic frequency changes more with the SOC of the battery.

8. A battery detection method, characterized in that, Including: Scan the battery in the medium and low frequency bands to obtain a first impedance spectrum; Determine a characteristic frequency according to the first impedance spectrum, where the characteristic frequency varies with the SOC of the battery; When the deviation of the characteristic frequency from a reference characteristic frequency satisfies a preset condition, scan the battery in the full frequency band to obtain a second impedance spectrum; the reference characteristic frequency is the characteristic frequency of the impedance spectrum when the SOC of the battery is a preset value; Determine the SOC of the battery according to the second impedance spectrum; When the SOC of the battery satisfies an alarm condition, generate an alarm signal.

9. A energy storage system, characterized in that, Including a battery and a battery management system; The battery management system is used to execute the battery detection method according to any one of claims 1 to 8.

10. An electrified device, characterized in that, Including a device main body and the energy storage system according to claim 9 above provided on the device main body.

Images