A battery impedance spectroscopy online measurement system and method

Abstract

This invention provides an online battery impedance spectrum measurement system, belonging to the technical field of online measurement systems. The system includes: an excitation source for injecting an AC excitation signal into a battery string under test; a switch array composed of multiple controllable switches for selectively connecting the excitation signal to different battery combinations within the battery string; and a measurement unit for acquiring AC voltage signals across the terminals of the battery under test. Specifically, when measuring the nth and (n+1)th batteries, the corresponding switches are closed, causing the current to be shunt through the upper and lower bridge arms, then flowing through the switch array, injected into the corresponding two batteries, and finally returning to the excitation source. By changing the combination of the switch array, impedance measurements of different batteries can be achieved. This invention's system and method realize online real-time measurement of battery impedance spectra, significantly improving the timeliness of battery status monitoring.

Description

Technical Field

[0001] This invention relates to the technical field of online measurement systems, and more particularly to an online measurement system and method for battery impedance spectra. Background Technology

[0002] With the establishment of dual-carbon goals, electrochemical energy storage technology is being applied more and more widely in power systems, especially in new energy power plants in conjunction with clean energy generation, peak shaving, and frequency regulation. However, batteries, as the core component of electrochemical energy storage, lack effective means for detection. Electrochemical impedance spectroscopy is considered a method with high information density and strong mechanistic correlation in battery estimation, and is therefore widely used in battery estimation and other fields. Its basic principle is: to give the battery a small-amplitude sinusoidal excitation signal. Measure the response signal under the corresponding excitation. .in , and impedance The expression is as follows:

[0003] ; By changing the frequency of the excitation signal, the excitation and response signals at different frequencies are measured. The impedance information at the corresponding frequency can be obtained according to the above formula.

[0004] However, traditional impedance spectroscopy measurement techniques are widely used offline, mainly because the test conditions are harsh, the test time is long, the parameters such as SOC are sensitive, and expensive instruments are required. Summary of the Invention

[0005] In response to the technical problems mentioned in the background section, this invention provides an online battery impedance spectrum measurement system and method. This invention provides a low-cost, high-precision system and method capable of online measurement of the impedance spectra of multiple batteries.

[0006] The technical means employed in this invention are as follows: An online battery impedance spectrum measurement system, comprising: Excitation source, used to inject AC excitation signal into the battery string under test; A switch array, consisting of multiple controllable switches, is used to selectively connect the excitation signal to different battery combinations in the battery string under test. The measurement unit is used to acquire the AC voltage signal across the two ends of the battery under test; Specifically, when measuring the nth and n+1th batteries, the corresponding switches are closed to allow the current to be shunt through the upper and lower bridge arms, then flow through the switch array, injected into the corresponding two batteries, and then flow back to the excitation source; by changing the combination of the switch array, impedance measurement of different batteries can be achieved.

[0007] Furthermore, it also includes: a data compensation module, used to remeasure the battery by changing the combination of the switch array when the battery internal resistance difference is too large, causing the bridge to be unbalanced, and to correct the error based on the data from multiple measurements; The remeasurement combinations include: single battery measurement, changing the measurement order of multiple batteries, and multiple battery combination measurement, so that each battery is measured multiple times.

[0008] Furthermore, the data compensation module employs a data compensation method based on a reconstructed circuit, including the following steps: By comparing the impedance of the two cells under test during measurement, the weighting factor is adaptively adjusted to achieve self-calibration of the measured impedance. The corrective compensation formula is: ; ; .

[0009] Furthermore, the data compensation module is also used to: simultaneously measure the disturbance voltage of other unmeasured batteries when measuring batteries n+1 and n+2, and perform self-correction on the impedance measurement results based on the disturbance voltage.

[0010] Furthermore, it also includes: an error assessment unit, used to assess the load current. The size measures the measurement error; Among them, load current The expression is: ; in Indicates the load resistance; Indicates the impedance of the upper and lower bridge arms; Indicates battery impedance; when Simplified to: ; The greater the impedance difference between the two batteries under test, the greater the load current. The larger the value, the greater the measurement error.

[0011] The present invention also includes a method for measuring battery impedance, characterized by comprising the following steps: S1: Close the corresponding switch in the switch array to connect the excitation signal to the nth battery and the (n+1)th battery for the first impedance measurement; S2: Determine if the difference in battery internal resistance is too large. If so, proceed to step S3. S3: Change the combination of the switch array and remeasure the battery so that each battery is measured multiple times; S4: Based on data from multiple measurements, the error data is corrected through adaptive weight adjustment to obtain the corrected battery impedance value.

[0012] Furthermore, the adaptive weight adjustment described in S4 includes: The weighting factor is determined based on the impedance difference between the two battery pairs measured. The greater the impedance difference, the lower the weight of the corresponding measurement result.

[0013] Compared with the prior art, the present invention has the following advantages: The system and method of this invention realize the online real-time measurement function of battery impedance spectrum, which greatly improves the timeliness of battery status monitoring. The full coverage measurement of the entire battery cluster can be completed with a single set of equipment, which significantly reduces the system hardware cost and deployment complexity. At the same time, in order to address the bridge imbalance error caused by the difference in battery internal resistance during the measurement process, an adaptive data compensation method based on circuit reconstruction is proposed. By changing the combination of switch arrays to achieve multiple measurements and weight optimization, the measurement deviation introduced by load current is effectively eliminated, ensuring the accuracy and reliability of impedance spectrum data. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0017] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0018] like Figure 1 As shown, this invention provides an online battery impedance spectrum measurement system, comprising: an excitation source for injecting an AC excitation signal into a battery string under test; a switch array composed of multiple controllable switches for selectively connecting the excitation signal to different battery combinations in the battery string under test; and a measurement unit for acquiring AC voltage signals across the terminals of the battery under test. Specifically, when measuring the nth battery and the (n+1)th battery, the corresponding switch is closed to shunt the current through the upper and lower bridge arms, then through the switch array, injecting it into the corresponding two batteries before returning to the excitation source. By changing the combination of the switch array, impedance measurement of different batteries can be achieved.

[0019] In a preferred embodiment, the system further includes a data compensation module, used to remeasure the battery by changing the combination of the switch array when the battery internal resistance difference is too large, causing the bridge to be unbalanced, and to correct the error based on the data from multiple measurements; wherein the remeasurement combination includes: single battery measurement, changing the measurement order of multiple batteries, and multiple battery combination measurement, so that each battery is measured multiple times.

[0020] Preferably, the data compensation module in this application adopts a data compensation method based on reconstructed circuits, including the following steps: by comparing the impedance of the two batteries under test during measurement, the weighting factor is adaptively adjusted to achieve self-correction of the measured impedance; The corrective compensation formula is: ; ; .

[0021] The data compensation module is also used to: simultaneously measure the disturbance voltage of other unmeasured batteries when measuring batteries n+1 and n+2, and perform self-correction on the impedance measurement results based on the disturbance voltage.

[0022] In a preferred embodiment, the system further includes an error assessment unit, configured to assess the load current. The size measures the measurement error; Among them, load current The expression is: ; in Indicates the load resistance; Indicates the impedance of the upper and lower bridge arms; Indicates battery impedance; when Simplified to: ; The greater the impedance difference between the two batteries under test, the greater the load current. The larger the value, the greater the measurement error.

[0023] Preferably, the present invention also includes a battery impedance measurement method, comprising the following steps: S1: Close the corresponding switch in the switch array to connect the excitation signal to the nth battery and the (n+1)th battery for the first impedance measurement; S2: Determine if the difference in battery internal resistance is too large. If so, proceed to step S3. S3: Change the combination of the switch array and remeasure the battery so that each battery is measured multiple times; S4: Based on data from multiple measurements, the error data is corrected through adaptive weight adjustment to obtain the corrected battery impedance value. The adaptive weight adjustment in S4 includes: The weighting factor is determined based on the impedance difference between the two battery pairs measured. The greater the impedance difference, the lower the weight of the corresponding measurement result.

[0024] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the above embodiments of the present invention, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. It should be understood that the disclosed technical content in the several embodiments provided in this application can be implemented in other ways.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An online battery impedance spectrum measurement system, characterized in that, include: Excitation source, used to inject AC excitation signal into the battery string under test; A switch array, consisting of multiple controllable switches, is used to selectively connect the excitation signal to different battery combinations in the battery string under test. The measurement unit is used to acquire the AC voltage signal across the two ends of the battery under test; When measuring the nth battery and the (n+1)th battery, the corresponding switch is closed to allow the current to be shunt through the upper and lower bridge arms, then flow through the switch array, injected into the corresponding two batteries, and then flow back to the excitation source. By changing the combination of the switch array, impedance measurement of different batteries can be achieved.

2. The online battery impedance spectrum measurement system according to claim 1, characterized in that, Also includes: The data compensation module is used to remeasure the battery by changing the combination of the switch array when the battery internal resistance difference is too large, causing the bridge to be unbalanced, and to correct the error based on the data from multiple measurements. The remeasurement combinations include: single battery measurement, changing the measurement order of multiple batteries, and multiple battery combination measurement, so that each battery is measured multiple times.

3. The online battery impedance spectrum measurement system according to claim 2, characterized in that, The data compensation module employs a data compensation method based on reconstructed circuits, including the following steps: By comparing the impedance of the two cells under test during measurement, the weighting factor is adaptively adjusted to achieve self-calibration of the measured impedance. The corrective compensation formula is: ； ； 。 4. The online battery impedance spectrum measurement system according to claim 2, characterized in that, The data compensation module is also used to: simultaneously measure the disturbance voltage of other unmeasured batteries when measuring batteries n+1 and n+2, and perform self-correction on the impedance measurement results based on the disturbance voltage.

5. A battery impedance spectrum online measurement system according to any one of claims 1-4, characterized in that, It also includes: an error evaluation unit, used to evaluate based on load current. The size measures the measurement error; Among them, load current The expression is: ； in Indicates the load resistance; Indicates the impedance of the upper and lower bridge arms; Indicates battery impedance; when Simplified to: ； The greater the impedance difference between the two batteries under test, the greater the load current. The larger the value, the greater the measurement error.

6. A method for measuring battery impedance based on the online measurement system according to any one of claims 1-5, characterized in that, Includes the following steps: S1: Close the corresponding switch in the switch array to connect the excitation signal to the nth battery and the (n+1)th battery for the first impedance measurement; S2: Determine if the difference in battery internal resistance is too large. If so, proceed to step S3. S3: Change the combination of the switch array and remeasure the battery so that each battery is measured multiple times; S4: Based on data from multiple measurements, the error data is corrected through adaptive weight adjustment to obtain the corrected battery impedance value.

7. The battery impedance measurement method according to claim 6, characterized in that, The adaptive weight adjustment described in S4 includes: The weighting factor is determined based on the impedance difference between the two battery pairs measured. The greater the impedance difference, the lower the weight of the corresponding measurement result.

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