Battery internal resistance measuring method and device

Abstract

According to the battery internal resistance measurement method and device, high-frequency oscillation signals are generated based on the temperature and current state of a target battery measured in real time and injected to the two ends of the target battery, and the influence of the temperature and current state on the battery internal resistance measurement result is fully considered; performing multi-band analysis on the AC voltage signals at the two ends of the target battery and the AC current signal in the target battery to obtain response characteristics of the target battery under different frequencies; and after the internal resistance value of the target battery in the preset frequency band range is calculated from the corresponding response characteristics by using a ratio method, the measured internal resistance value is corrected according to the real-time temperature and the current state, and finally the internal resistance measurement value of the target battery is obtained. The internal resistance measurement deviation possibly occurring in different environments can be effectively eliminated, and the problem that internal resistance measurement is inaccurate due to the fact that it is difficult to distinguish the internal electrochemical impedance and temperature of the battery and the influence of the current state on the battery performance is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery detection, and in particular relates to a method and device for measuring the internal resistance of a battery. Background Art

[0002] Existing battery internal resistance measurement methods are mostly based on traditional AC superposition or DC load methods, which usually require the injection of an AC signal or pulse signal of a certain amplitude, sampling of current and voltage, and calculation of the internal resistance based on the sampled values. However, in practical applications, due to the complexity of battery types and working environments, traditional methods are difficult to accurately distinguish the impact of the battery's internal electrochemical impedance and other internal environmental factors (such as temperature, current state, etc.) on battery performance, resulting in inaccurate battery internal resistance measurement. Summary of the invention

[0003] In view of this, an embodiment of the present invention provides a battery internal resistance measurement method and device, aiming to solve the problem of inaccurate battery internal resistance measurement caused by the difficulty in accurately distinguishing the influence of internal electrochemical impedance of the battery and temperature and current state on battery performance in traditional technical solutions.

[0004] A first aspect of an embodiment of the present invention provides a battery internal resistance measurement method, including: measuring the temperature and current state of a target battery in real time; generating a high-frequency oscillation signal based on the temperature and current state, and injecting the high-frequency oscillation signal into both ends of the target battery; respectively obtaining an AC voltage signal at both ends of the target battery and an AC current signal inside the target battery; performing multi-band analysis on the AC voltage signal and the AC current signal to obtain response characteristics of the AC voltage signal and the AC current signal at different frequencies; using a ratio method to calculate the internal resistance value of the target battery within a preset frequency band from the response characteristics; and correcting the internal resistance value within the preset frequency band according to the temperature and current state to obtain the internal resistance measurement value of the target battery.

[0005] In one embodiment, the current state includes a charging state or a discharging state of a target battery; generating a high-frequency oscillation signal based on the temperature and the current state includes: determining a frequency range of the high-frequency oscillation signal based on the temperature; adjusting the frequency range according to the charging state or the discharging state and generating a high-frequency oscillation signal within the corresponding frequency range.

[0006] In one embodiment, determining the frequency range of the high-frequency oscillation signal according to the temperature includes: in, It is the frequency value measured under standard conditions and is used as the reference frequency. and are the temperature adjustment coefficients, is the minimum value of the measurement frequency range adjusted according to temperature, is the maximum value of the measurement frequency range adjusted according to temperature.

[0007] In one embodiment, adjusting the frequency range according to the charging state or the discharging state includes: if the current state is the charging state, adjusting the frequency range to shift toward a high frequency band based on a preset first adjustment coefficient; If the current state is the discharge state, the frequency range is adjusted to shift toward the low frequency band based on a preset second adjustment coefficient.

[0008] In one embodiment, the internal resistance of the target battery within a preset frequency range is calculated from the response characteristics using a ratio method and expressed as: in, For the i Frequency points The internal resistance of the target battery, is the weight set according to the importance of the frequency point, N is the total number of frequency points within the frequency range, For the i Frequency points The amplitude of the AC voltage signal across the target battery, For the i The amplitude of the AC current signal inside the target battery at each frequency point.

[0009] In one embodiment, the internal resistance value within a preset frequency band is corrected according to the temperature and current state to obtain the internal resistance measurement value of the target battery, including: in, is the measured internal resistance of the target battery, The internal resistance calculation result of the target battery within the preset frequency range. To correct the temperature, is the temperature of the target battery at the current moment, The temperature of the target battery at the start of measurement, and are the temperature adjustment coefficients, is the correction factor for the charging or discharging state, is the frequency correction factor.

[0010] In one embodiment, before starting the target battery internal resistance measurement, it also includes: measuring the DC voltage and open circuit voltage at both ends of the target battery, determining that the fluctuations of the DC voltage and the open circuit voltage are both smaller than a preset fluctuation range, and that the voltage difference between the DC voltage and the open circuit voltage is within a preset voltage difference range.

[0011] In one embodiment, after the high-frequency oscillation signal is generated based on the temperature and current state, the method further includes: adjusting the frequency range of the high-frequency oscillation signal according to changes in the temperature and current state.

[0012] A second aspect of an embodiment of the present application provides a battery internal resistance measuring device, comprising: A detection module, used to measure the temperature and current status of the target battery in real time; A high-frequency oscillation signal generation module is used to generate a high-frequency oscillation signal based on temperature and current state, and inject the high-frequency oscillation signal into both ends of the target battery; A signal sampling module, used to obtain the AC voltage signal at both ends of the target battery and the AC current signal inside the target battery respectively; An analysis module, used for performing multi-band analysis on the AC voltage signal and the AC current signal to obtain the response characteristics of the AC voltage signal and the AC current signal at different frequencies; A calculation module, used to calculate the internal resistance value of the target battery within a preset frequency band from the response characteristics by using a ratio method; The correction module is used to correct the internal resistance value within a preset frequency band according to the temperature and current state to obtain the internal resistance measurement value of the target battery.

[0013] The beneficial effects of the embodiments of the present application are as follows: by generating a high-frequency oscillation signal based on the temperature and current state of the target battery measured in real time, and injecting it into both ends of the target battery, the influence of the temperature and current state on the battery internal resistance measurement result is fully considered; then, by performing multi-band analysis on the AC voltage signal at both ends of the target battery and the AC current signal inside the target battery, the response characteristics of the target battery at different frequencies are obtained; then, the internal resistance value of the target battery within the preset frequency band is calculated from the corresponding response characteristics using the ratio method, and the measured internal resistance value is corrected according to the real-time temperature and current state, and finally the internal resistance measurement value of the target battery is obtained. It can effectively eliminate the internal resistance measurement deviation that may occur in different environments, so as to solve the problem of inaccurate internal resistance measurement caused by the difficulty in distinguishing the internal electrochemical impedance of the battery and the influence of temperature and current state on battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 A schematic diagram of a flow chart of a battery internal resistance measurement method provided in an embodiment of the present application; Figure 2 A schematic diagram of the structure of a battery internal resistance measuring device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0016] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0018] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0019] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0020] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0021] In the description of the embodiments of the present application, the term "multi-frame" refers to more than two (including two).

[0022] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0023] The embodiment of the present invention provides a battery internal resistance measurement method, and the battery internal resistance measurement method is applied to a battery internal resistance measurement device. Figure 1 As shown, Figure 1 A schematic diagram of a flow chart of a battery internal resistance measurement method provided in an embodiment of the present application. Figure 1 It can be seen that the battery internal resistance measurement method provided in the embodiment of the present application includes: S101: Measure the temperature and current state of the target battery in real time.

[0024] The temperature of the target battery is a key factor affecting its internal resistance. The internal resistance of the battery usually changes with temperature. In this application, the temperature of the target battery can be monitored in real time by a temperature sensor (such as a thermocouple, thermistor, etc.).

[0025] The current state of the target battery includes a charging state or a discharging state. The current state also has a significant effect on its internal resistance. In the charging state, the battery's chemical reaction rate, ion migration, and the response of the electrolyte and electrode materials inside the battery will be different from those during discharge. This usually causes the battery's internal resistance to behave differently during charging than during discharge. During the discharge process, the battery's internal resistance is often affected by changes in the battery's internal charge consumption, the reduction in reactant concentration, and the reaction characteristics of the battery electrodes. In the present application, the charging current can be obtained by a current sensor, and the discharge current value can also be obtained by a current sensor.

[0026] By acquiring the temperature and current status of the target battery in real time, the precision and accuracy of the battery internal resistance measurement can be ensured.

[0027] S102: Generate a high-frequency oscillation signal based on the temperature and current state, and inject the high-frequency oscillation signal into two ends of the target battery.

[0028] Generate a high-frequency oscillation signal based on temperature and current state, including: determining the frequency range of the high-frequency oscillation signal based on temperature; adjusting the frequency range according to the charging state or the discharging state and generating a high-frequency oscillation signal within the corresponding frequency range.

[0029] In one embodiment, determining the frequency range of the high-frequency oscillation signal according to the temperature includes: in, It is the frequency value measured under standard conditions and is used as the reference frequency. and are the temperature adjustment coefficients, is the minimum value of the measurement frequency range adjusted according to temperature, is the maximum value of the measurement frequency range adjusted according to temperature.

[0030] In one embodiment, adjusting the frequency range according to the charging state or the discharging state includes: if the current state is the charging state, adjusting the frequency range to shift toward a high frequency band based on a preset first adjustment coefficient; If the current state is the discharge state, the frequency range is adjusted to shift toward the low frequency band based on a preset second adjustment coefficient.

[0031] Among them, the value of the first adjustment coefficient is greater than 1, and the value of the second adjustment coefficient is greater than 0 and less than 1.

[0032] S103: Acquire the AC voltage signal at both ends of the target battery and the AC current signal inside the target battery respectively.

[0033] A high-precision AC voltage sensor is used to collect the AC voltage signal at both ends of the target battery, and a current sensor is used to monitor the changes in battery current to capture the AC current signal inside the battery. Specifically, a high-frequency oscillation signal within a certain frequency range is injected at both ends of the target battery. The high-frequency oscillation signal is affected by the internal impedance of the target battery, and finally an AC voltage signal is generated at both ends of the target battery. The AC current signal of the target battery is the current fluctuation generated by the injected AC signal and the reaction inside the battery. The AC current signal reflects the current distribution, reaction and impedance characteristics inside the target battery.

[0034] S104: Perform multi-frequency analysis on the AC voltage signal and the AC current signal to obtain response characteristics of the AC voltage signal and the AC current signal at different frequencies.

[0035] The internal resistance and other electrochemical parameters of the target battery usually show different characteristics at different frequencies. Therefore, by performing multi-frequency analysis on the AC voltage signal and AC current signal at both ends of the target battery, we can have a more comprehensive understanding of the electrochemical response of the target battery at different frequencies, thereby estimating its internal resistance more accurately.

[0036] In this application, the fast Fourier transform is used to perform frequency domain analysis on the AC voltage signal and the AC current signal, decompose the time domain signal into multiple frequency components, and calculate the amplitude of each frequency component. Through this analysis process, the amplitude of the voltage signal and the amplitude of the current signal corresponding to each frequency point are obtained, thereby forming the voltage and current response characteristics at different frequencies. These response characteristics can accurately reflect the law of the change of the internal resistance of the target battery with frequency, and provide more accurate data support for the internal resistance measurement.

[0037] S105: Calculate the internal resistance of the target battery within a preset frequency band from the response characteristics using a ratio method.

[0038] Exemplarily, the internal resistance of the target battery within a preset frequency range is calculated from the response characteristics using the ratio method and expressed as: in, For the i Frequency points The internal resistance of the target battery, is the weight set according to the importance of the frequency point, N is the total number of frequency points within the frequency range, For the i Frequency points The amplitude of the AC voltage signal across the target battery, For the i Frequency points The amplitude of the AC current signal inside the target battery.

[0039] By combining the ratio method with multi-band analysis and considering the weight of each frequency point, the internal resistance of the target battery can be calculated more accurately.

[0040] S106: Correcting the internal resistance value within the preset frequency band according to the temperature and current state to obtain the internal resistance measurement value of the target battery.

[0041] In one embodiment, the internal resistance value within a preset frequency band is corrected according to the temperature and current state to obtain the internal resistance measurement value of the target battery, including: in, is the measured internal resistance of the target battery, The internal resistance calculation result of the target battery within the preset frequency range. To correct the temperature, is the temperature of the target battery at the current moment, The temperature of the target battery at the start of measurement, and are the temperature adjustment coefficients, is the correction factor for the charging or discharging state, is the frequency correction factor.

[0042] By introducing comprehensive corrections of temperature, charge and discharge state and frequency correction factor into the internal resistance measurement, the internal resistance value of the target battery can be calculated more accurately.

[0043] In one embodiment, before starting the target battery internal resistance measurement, the method further includes: measuring the DC voltage and open circuit voltage at both ends of the target battery, and determining that the fluctuations of the DC voltage and the open circuit voltage are both less than a preset fluctuation range, and the voltage difference between the DC voltage and the open circuit voltage is within a preset voltage difference range. By ensuring that the voltage of the target battery is stable, a stable measurement environment is provided for the internal resistance measurement.

[0044] In one embodiment, after the high-frequency oscillation signal is generated based on the temperature and current state, the method further includes: adjusting the frequency range of the high-frequency oscillation signal according to changes in the temperature and current state.

[0045] By adjusting the frequency range according to the temperature and current status, the process of measuring the internal resistance of the target battery is further optimized and the reliability of the measurement is improved.

[0046] Through the above analysis, it can be known that the battery internal resistance measurement method provided by the present application generates a high-frequency oscillation signal based on the temperature and current state of the target battery measured in real time, and injects it into both ends of the target battery, fully considering the influence of temperature and current state on the battery internal resistance measurement result; then, by performing multi-band analysis on the AC voltage signal at both ends of the target battery and the AC current signal inside the target battery, the response characteristics of the target battery at different frequencies are obtained; then, the internal resistance value of the target battery within the preset frequency band is calculated from the corresponding response characteristics using the ratio method, and the measured internal resistance value is corrected according to the real-time temperature and current state, and finally the internal resistance measurement value of the target battery is obtained. It can effectively eliminate the internal resistance measurement deviation that may occur in different environments, so as to solve the problem of inaccurate internal resistance measurement caused by the difficulty in distinguishing the internal electrochemical impedance of the battery and the influence of temperature and current state on battery performance.

[0047] See also Figure 2 As shown, Figure 2 A schematic diagram of the structure of a battery internal resistance measurement device provided in one embodiment of the present application. Figure 2 It can be seen that the battery internal resistance measurement device provided in the embodiment of the present application includes: The detection module 201 is used to measure the temperature and current state of the target battery in real time.

[0048] The high-frequency oscillation signal generating module 202 is used to generate a high-frequency oscillation signal based on the temperature and current state, and inject the high-frequency oscillation signal into both ends of the target battery.

[0049] The signal sampling module 203 is used to respectively obtain the AC voltage signal at both ends of the target battery and the AC current signal inside the target battery.

[0050] The analysis module 204 is used to perform multi-band analysis on the AC voltage signal and the AC current signal to obtain response characteristics of the AC voltage signal and the AC current signal at different frequencies.

[0051] The calculation module 205 is used to calculate the internal resistance value of the target battery within a preset frequency band from the response characteristics by using a ratio method.

[0052] The correction module 206 is used to correct the internal resistance value within a preset frequency band according to the temperature and current state to obtain the internal resistance measurement value of the target battery.

[0053] In the present application, the functions of the analysis module, the calculation module and the correction module can be completed by a programmable logic controller. Specifically, the present application does not impose any limitation on the programmable logic controller.

[0054] It should be noted that the specific implementation process of each module in the battery internal resistance measurement device provided in this application can refer to Figure 1 The specific implementation process of the battery internal resistance measurement method in the embodiment will not be repeated here.

[0055] The beneficial effects of the embodiments of the present application are as follows: by generating a high-frequency oscillation signal based on the temperature and current state of the target battery measured in real time, and injecting it into both ends of the target battery, the influence of the temperature and current state on the battery internal resistance measurement result is fully considered; then, by performing multi-band analysis on the AC voltage signal at both ends of the target battery and the AC current signal inside the target battery, the response characteristics of the target battery at different frequencies are obtained; then, the internal resistance value of the target battery within the preset frequency band is calculated from the corresponding response characteristics using the ratio method, and the measured internal resistance value is corrected according to the real-time temperature and current state, and finally the internal resistance measurement value of the target battery is obtained. It can effectively eliminate the internal resistance measurement deviation that may occur in different environments, so as to solve the problem of inaccurate internal resistance measurement caused by the difficulty in distinguishing the internal electrochemical impedance of the battery and the influence of temperature and current state on battery performance.

[0056] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0057] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0058] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for measuring battery internal resistance, characterized in that: include: measuring the temperature and current state of the target battery in real time; generating a high-frequency oscillation signal based on the temperature and the current state, and injecting the high-frequency oscillation signal into two ends of the target battery; Respectively acquiring an AC voltage signal at both ends of the target battery and an AC current signal inside the target battery; Performing multi-band analysis on the AC voltage signal and the AC current signal to obtain response characteristics of the AC voltage signal and the AC current signal at different frequencies; Calculating the internal resistance of the target battery within a preset frequency range from the response characteristics using a ratio method; According to the temperature and the current state, the internal resistance value within the preset frequency band is corrected to obtain the internal resistance measurement value of the target battery.

2. The battery internal resistance measurement method according to claim 1, characterized in that: The current state includes a charging state or a discharging state of the target battery; and generating a high-frequency oscillation signal based on the temperature and the current state includes: determining a frequency range of the high-frequency oscillation signal based on the temperature; According to the charging state or the discharging state, the frequency range is adjusted and a high-frequency oscillation signal within the corresponding frequency range is generated.

3. The battery internal resistance measurement method according to claim 2, characterized in that: The step of determining the frequency range of the high-frequency oscillation signal according to the temperature includes: in, It is the frequency value measured under standard conditions and is used as the reference frequency. and are the temperature adjustment coefficients, is the minimum value of the measurement frequency range adjusted according to temperature, is the maximum value of the measurement frequency range adjusted according to temperature.

4. The battery internal resistance measurement method according to claim 2, characterized in that: The adjusting the frequency range according to the charging state or the discharging state includes: If the current state is a charging state, adjusting the frequency range to shift toward a high frequency band based on a preset first adjustment coefficient; If the current state is a discharge state, the frequency range is adjusted to shift toward a low frequency band based on a preset second adjustment coefficient.

5. The battery internal resistance measurement method according to claim 1, characterized in that: The internal resistance value of the target battery within the preset frequency range is calculated from the response characteristics using the ratio method and is expressed as: in, For the i Frequency points The internal resistance of the target battery, is the weight set according to the importance of the frequency point, N is the total number of frequency points within the frequency range, For the i At each frequency point, the amplitude of the AC voltage signal at both ends of the target battery is For the i The amplitude of the AC current signal inside the target battery at each frequency point.

6. The method for measuring the internal resistance of a battery as claimed in claim 5, characterized in that: The step of correcting the internal resistance value within the preset frequency band according to the temperature and the current state to obtain the internal resistance measurement value of the target battery includes: in, is the measured internal resistance of the target battery, The internal resistance calculation result of the target battery within the preset frequency range. To correct the temperature, is the temperature of the target battery at the current moment, The temperature of the target battery at the start of measurement, and are the temperature adjustment coefficients, is the correction factor for the charging or discharging state, is the frequency correction factor.

7. The battery internal resistance measurement method according to any one of claims 1 to 6, characterized in that: Before starting the target battery internal resistance measurement, it also includes: measuring the DC voltage and the open circuit voltage at both ends of the target battery, determining that the fluctuations of the DC voltage and the open circuit voltage are both less than a preset fluctuation range, and that the voltage difference between the DC voltage and the open circuit voltage is within a preset voltage difference range.

8. The method for measuring the internal resistance of a battery as claimed in claim 7, characterized in that: After generating the high-frequency oscillation signal based on the temperature and the current state, the method further includes: adjusting the frequency range of the high-frequency oscillation signal according to changes in the temperature and the current state.

9. A battery internal resistance measuring device, characterized in that: include: A detection module, used for measuring the temperature and current state of the target battery in real time; A high-frequency oscillation signal generating module, used to generate a high-frequency oscillation signal based on the temperature and the current state, and inject the high-frequency oscillation signal into both ends of the target battery; A signal sampling module, used to respectively obtain an AC voltage signal at both ends of the target battery and an AC current signal inside the target battery; An analysis module, used for performing multi-band analysis on the AC voltage signal and the AC current signal to obtain response characteristics of the AC voltage signal and the AC current signal at different frequencies; A calculation module, used to calculate the internal resistance value of the target battery within a preset frequency band from the response characteristics by using a ratio method; The correction module is used to correct the internal resistance value within the preset frequency band according to the temperature and the current state to obtain the internal resistance measurement value of the target battery.

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