Method and device for monitoring health state of battery on line

Abstract

The invention discloses a method and device for monitoring the health state of a battery on line, and the method comprises the steps: determining the current load transfer resistance of a to-be-monitored battery according to the Nyquist curve data of the to-be-monitored battery at the current temperature; converting the current charge transfer resistance of the to-be-monitored battery at the current temperature to the charge transfer resistance at the preset temperature; and determining the current health state of the to-be-monitored battery according to the charge transfer resistance of the to-be-monitored battery at the preset temperature and a second preset corresponding relation. Determining the health state of the to-be-monitored battery according to the corresponding relation between the charge transfer resistance and the health state and the charge transfer resistance of the to-be-monitored battery, and after the charge transfer resistance of the to-be-monitored battery at the current temperature is obtained, converting the charge transfer resistance at the current temperature to the charge transfer resistance at the preset temperature through a certain mapping relation, the influence of the temperature on the charge transfer resistance is eliminated, and the accuracy of monitoring the health state of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a method and device for online monitoring of the health status of a battery. Background Art

[0002] With the continuous advancement of battery technology, lithium-ion batteries have become the main choice in electric vehicles, energy storage systems and other fields due to their high energy density, long cycle health status and low self-discharge rate. However, as the battery is used for a longer time, its performance will gradually decline, such as capacity decay, increased charge transfer resistance, etc. These problems directly affect the health status and overall performance of the battery. Therefore, accurately measuring the battery's state of health (SOH) is crucial to evaluating battery performance and ensuring the normal operation of equipment.

[0003] The health status of a battery is not only related to aging, but also affected by the battery's usage status. In the prior art, the error in estimating the health status of a battery using the number of charge and discharge cycles is relatively large. Summary of the invention

[0004] The present invention provides a method and device for online monitoring of the health status of a battery, so as to improve the accuracy of determining the health status of the battery.

[0005] According to one aspect of the present invention, a method for online monitoring of a battery health state is provided, comprising:

[0006] When it is determined that the battery to be monitored meets the preset condition, the current charge transfer resistance of the battery to be monitored is determined according to the Nyquist curve data of the battery to be monitored at the current temperature;

[0007] Converting the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at a preset temperature;

[0008] The current health status of the battery to be monitored is determined based on the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset correspondence; wherein the second preset correspondence includes, at a preset temperature, multiple charge transfer resistors and the health status corresponding to each of the charge transfer resistors.

[0009] Optionally, converting the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at a preset temperature includes:

[0010] Determining the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature;

[0011] The first preset corresponding relationship is the corresponding relationship between the charge transfer resistance and the temperature of the battery to be monitored, and the first preset corresponding relationship satisfies:

[0012] Rct=x*T*exp(a / T), wherein Rct is the charge transfer resistance, x is the first parameter related to the health status, T is the temperature, and a is the set constant.

[0013] Optionally, before determining the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature, the method further includes:

[0014] Generate charge transfer resistances corresponding to the test battery at different temperatures according to Nyquist curve data at at least two different temperatures when the test battery is at a preset remaining power;

[0015] The set constant is calculated based on the charge transfer resistance corresponding to the test battery at at least two different temperatures.

[0016] Optionally, before determining the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature, the method further includes:

[0017] Obtaining correction coefficients of at least two test batteries, and determining the set constant according to the correction coefficients of each of the test batteries;

[0018] For any of the test batteries, obtaining a correction factor of the test battery includes:

[0019] Generate charge transfer resistances corresponding to the test battery at different temperatures according to Nyquist curve data at at least two different temperatures when the test battery is at a preset remaining power;

[0020] According to the charge transfer resistance corresponding to the test battery at at least two different temperatures, a set constant corresponding to the test battery is calculated and used as a correction coefficient of the test battery.

[0021] Optionally, determining the current health state of the battery to be monitored according to the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset corresponding relationship includes:

[0022] When there is a reference charge transfer resistor among the multiple charge transfer resistors included in the second preset corresponding relationship, the health state corresponding to the reference charge transfer resistor is used as the current health state of the battery to be monitored; the reference charge transfer resistor is equal to the charge transfer resistance of the battery to be monitored at a preset temperature;

[0023] When there is no reference charge transfer resistor among the multiple charge transfer resistors included in the second preset corresponding relationship, the current health state of the battery to be monitored is determined by interpolation calculation.

[0024] Optionally, the health state included in the second preset corresponding relationship is recorded as the binding point health state, and before determining the current health state of the battery to be monitored according to the charge transfer resistance of the battery to be monitored at a preset temperature and the second preset corresponding relationship, the method further includes:

[0025] Determine the charge transfer resistance corresponding to the health state of each binding point according to the Nyquist curve data corresponding to the health state of each binding point at the preset remaining power and the preset temperature of the test battery;

[0026] The health status of each of the binding points and its corresponding load transfer resistance constitute the second preset corresponding relationship.

[0027] Optionally, for the test battery, determining the health status of any of the binding points includes:

[0028] Completely charging and discharging the test battery to obtain the current remaining power of the test battery;

[0029] The binding point health status of the test battery is determined according to the current remaining power of the test battery and the initial remaining power of the test battery.

[0030] The preset conditions include:

[0031] The battery to be monitored is in a static state within a preset time, and the remaining power of the battery to be monitored is between 20% and 80%; wherein, in the static state, the current value of the battery to be monitored is less than or equal to the current setting value.

[0032] According to another aspect of the present invention, there is provided a device for online monitoring of battery health status, comprising:

[0033] A current charge transfer resistance determination module, used to determine the current charge transfer resistance of the battery to be monitored according to the Nyquist curve data of the battery to be monitored at the current temperature when it is determined that the battery to be monitored meets the preset conditions;

[0034] A preset charge transfer resistance determination module, used to convert the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at a preset temperature;

[0035] A health status determination module is used to determine the current health status of the battery to be monitored based on the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset correspondence; wherein the second preset correspondence includes, at a preset temperature, multiple charge transfer resistors and the health status corresponding to each of the charge transfer resistors.

[0036] Optionally, the preset charge transfer resistance determination module includes:

[0037] a preset charge transfer resistance determining unit, configured to determine the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature;

[0038] The first preset corresponding relationship is the corresponding relationship between the charge transfer resistance and the temperature of the battery to be monitored, and the first preset corresponding relationship satisfies:

[0039] Rct=x*T*exp(a / T), wherein Rct is the charge transfer resistance, x is the first parameter related to the health status, T is the temperature, and a is the set constant.

[0040] The technical solution of the embodiment of the present invention, after obtaining the charge transfer resistance of the battery to be monitored at the current temperature, converts the charge transfer resistance at the current temperature to the charge transfer resistance at the preset temperature through a certain mapping relationship, eliminates the influence of temperature on the charge transfer resistance, and then obtains the current health state of the battery according to the charge transfer resistance at the preset temperature and the corresponding relationship based on the multiple groups of charge transfer resistances and the health state. The charge transfer resistance is related to battery aging, and as the battery ages, the charge transfer resistance of the battery changes significantly. Therefore, in this embodiment, the health state of the battery to be monitored is determined by the charge transfer resistance of the battery to be monitored through the corresponding relationship between the charge transfer resistance and the health state. At the same time, after obtaining the charge transfer resistance of the battery to be monitored at the current temperature, converts the charge transfer resistance at the current temperature to the charge transfer resistance at the preset temperature through a certain mapping relationship, eliminates the influence of temperature on the charge transfer resistance, and improves the accuracy of monitoring the health state of the battery.

[0041] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0043] Figure 1 A flowchart of a method for online monitoring of the health status of a battery provided by an embodiment of the present invention;

[0044] Figure 2A Nyquist curve diagram of a battery to be monitored provided by an embodiment of the present invention;

[0045] Figure 3 An equivalent circuit model diagram of a battery to be monitored provided by an embodiment of the present invention;

[0046] Figure 4 A flowchart of another method for online monitoring of the health status of a battery provided by an embodiment of the present invention;

[0047] Figure 5 A schematic diagram of the structure of another device for online monitoring of battery health status provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0049] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] Figure 1 This is a flowchart of a method for online monitoring of the health status of a battery provided by an embodiment of the present invention. This embodiment is applicable to the case of real-time monitoring of the health status of a battery. The method can be performed by an online monitoring device for the health status of a battery. The online monitoring device for the health status of a battery can be implemented in the form of hardware and / or software. The online monitoring device for the health status of a battery can be configured in an electric vehicle. Figure 1 As shown, the method includes:

[0051] S110: When it is determined that the battery to be monitored meets the preset condition, the current charge transfer resistance of the battery to be monitored is determined according to the Nyquist curve data of the battery to be monitored at the current temperature.

[0052] The Nyquist curve is a curve obtained by drawing the data obtained after the battery is swept and measured, representing the impedance performance of the battery at different frequencies. At the current moment, the electrochemical impedance spectroscopy (EIS) measurement is performed on the monitored battery to obtain the Nyquist curve data of the monitored battery at the current temperature. The Nyquist curve data refers to a set of data, specifically impedance data at multiple different frequencies. EIS measurement is to study the electrical properties of the material by applying an AC signal with a frequency range change and measuring the response of the system. The EIS technology is based on the parallel current field perturbation model. By establishing a uniform current field between parallel conductive surfaces, when the impedance of a certain area in the current field changes, the current distribution will be disturbed. By detecting these disturbances, the impedance distribution inside the material can be inferred. It should be noted that the Nyquist curve data does not specifically refer to the frequency data of the battery. The electrochemical impedance spectrum (EIS) specifically refers to the battery data. The Nyquist curve data in this article is actually the electrochemical impedance spectrum (EIS) data. The data is plotted into a curve graph. We call this graph the electrochemical impedance spectrum or Nyquist curve graph. The current temperature is the temperature obtained by a temperature sensor set within a preset distance of the battery to be monitored at the current moment. Specifically, the electrochemical impedance spectroscopy (EIS) measurement of the battery to be monitored is a process of discharging the battery with a small current at different frequencies and obtaining the battery impedance according to the voltage and current of the battery. Figure 2 A Nyquist curve diagram of a battery to be monitored provided by an embodiment of the present invention, Figure 2 The horizontal axis is the real part of the impedance Re, and the vertical axis is the imaginary part of the impedance Zi. By analyzing and calculating the curve graph, the equivalent circuit model diagram of the battery to be monitored can be obtained, such as Figure 3 As shown, Figure 3 An equivalent circuit model diagram of a battery to be monitored provided in an embodiment of the present invention includes an ohmic resistor Rb, a solid electrolyte resistor Rsei, a solid electrolyte capacitor Csei, a charge transfer resistor, a double-layer capacitor Cd1, and a diffusion resistor W. The specific connection relationship is as follows: Figure 3 As shown, no further details will be given here. According to the Nyquist curve data and Figure 3 The equivalent circuit model diagram shown is used to obtain the charge transfer resistance of the battery to be monitored through certain calculations.

[0053] The ohmic resistance Rb, the solid electrolyte resistance Rsei, and the charge transfer resistance will gradually increase with the aging of the battery. Among them, the change of the charge transfer resistance is significant, so the charge transfer resistance is selected to characterize the health status of the battery. The charge transfer resistance is affected by many factors such as temperature, the remaining capacity of the battery (State of Charge, also called the remaining capacity), the health status and the use status (charging and discharging current). If you want to characterize the health status of the battery with the charge transfer resistance, you must exclude the influence of its temperature, remaining capacity and use status. However, the charge transfer resistance does not show a monotonic change trend with the decrease of the remaining capacity of the battery, and the relationship is complicated. When the remaining capacity of the battery is high (such as greater than 90%) and the remaining capacity of the battery is low (such as less than 19%), the charge transfer resistance has a larger value, and the battery with a remaining capacity between 19%-90% has a smaller charge transfer resistance and the charge transfer resistance of the battery is similar at different remaining capacities. Therefore, when determining the health status of the battery based on the charge transfer resistance, the preset conditions must be met, and the preset conditions include: the battery to be monitored is in a static state within a preset time, and the remaining power of the battery to be monitored is between 20%-80%; wherein, in the static state, the current value of the battery to be monitored is less than or equal to the current setting value. In the static state, the battery to be monitored is neither charged nor discharged, and its current value is less than or equal to the current setting value, such as 200mA. Among them, the preset time length can be one hour, which can be set according to needs and is not specifically limited. At the same time, in this embodiment, the online monitoring method in this embodiment is used to monitor the health status of the battery for batteries with a capacity of 20%-80%, thereby eliminating the influence of the remaining power and usage status of the battery. At the same time, the health status of the battery generally does not undergo a sudden change in a short period of time, so it is reasonable to measure when the battery is not working, that is, in a static state. Specifically, before step S110, it also includes: monitoring the current value of the battery to be monitored; starting the timer when the current value of the battery to be monitored is less than or equal to the current setting value, until the timer counts to a preset time length, and determining that the battery to be monitored is in a static state; when the current value of the battery to be monitored is greater than the current setting value, the timer stops timing and is reset.

[0054] At the same time, the remaining power of the battery to be monitored is monitored. When the battery to be monitored satisfies both the conditions of being in a static state and the remaining power of the battery to be monitored is between 20% and 80%, step S110 is executed.

[0055] S120: Converting the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at a preset temperature.

[0056] There is a corresponding relationship between the charge transfer resistance and temperature of the battery to be monitored. One temperature can correspond to one charge transfer resistance. The corresponding charge transfer resistance at different temperatures can be obtained by conducting a large number of experiments on the test battery in the early stage, and then the mapping relationship between temperature and charge transfer resistance can be obtained, and the mapping relationship between the temperature and charge transfer resistance of the test battery is used as the mapping relationship between the temperature and charge transfer resistance of the battery to be monitored. The current charge transfer resistance of the battery to be monitored is the charge transfer resistance of the battery to be monitored at the current moment. The charge transfer resistance of the battery to be monitored at the current temperature is converted to the preset temperature through a certain mapping relationship to obtain the charge transfer resistance of the battery to be monitored at the preset temperature, thereby eliminating the influence of the battery's charge transfer resistance gradually increasing with the decrease in temperature. By converting the charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at the preset temperature, so that the health status of the battery to be monitored can be determined based on the charge transfer resistance at the preset temperature, the influence of temperature on the charge transfer resistance is eliminated, making it possible to determine the health status of the battery based on the charge transfer resistance. Optionally, the preset temperature is 25°C, which is closer to room temperature and reduces errors.

[0057] S130: Determine the current health status of the battery to be monitored based on the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset corresponding relationship; wherein the second preset corresponding relationship includes multiple charge transfer resistors and the health status corresponding to each charge transfer resistor at the preset temperature.

[0058] The state of health (SOH) of a battery is used to describe the performance and remaining life of the battery. The second preset correspondence may be in the form of a table, which includes multiple groups of data, each group of data including a charge transfer resistor and a health state corresponding to the charge transfer resistor. After determining the charge transfer resistor of the battery to be monitored at a preset temperature, the health state of the battery to be monitored is determined by looking up a table or interpolating.

[0059] The technical solution of the embodiment of the present invention, after obtaining the charge transfer resistance of the battery to be monitored at the current temperature, converts the charge transfer resistance at the current temperature to the charge transfer resistance at the preset temperature through a certain mapping relationship, eliminates the influence of temperature on the charge transfer resistance, and then obtains the current health state of the battery according to the charge transfer resistance at the preset temperature and the corresponding relationship based on the multiple groups of charge transfer resistances and the health state. The charge transfer resistance is related to battery aging, and as the battery ages, the charge transfer resistance of the battery changes significantly. Therefore, in this embodiment, the health state of the battery to be monitored is determined by the charge transfer resistance of the battery to be monitored through the corresponding relationship between the charge transfer resistance and the health state. At the same time, after obtaining the charge transfer resistance of the battery to be monitored at the current temperature, converts the charge transfer resistance at the current temperature to the charge transfer resistance at the preset temperature through a certain mapping relationship, eliminates the influence of temperature on the charge transfer resistance, and improves the accuracy of monitoring the health state of the battery.

[0060] Figure 4 A flowchart of another method for online monitoring of the health status of a battery provided by an embodiment of the present invention, referring to Figure 4 , optionally, the method includes:

[0061] S111: When it is determined that the battery to be monitored meets the preset condition, the current charge transfer resistance of the battery to be monitored is determined according to the Nyquist curve data of the battery to be monitored at the current temperature.

[0062] S121: Determine the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature.

[0063] The first preset corresponding relationship is the corresponding relationship between the charge transfer resistance and the temperature of the battery to be monitored, and the first preset corresponding relationship satisfies:

[0064] Rct=x*T*exp(a / T), wherein Rct is the charge transfer resistance, x is the first parameter related to the health status, T is the temperature, and a is the set constant.

[0065] By conducting multiple experiments on the test battery, the size of the battery's charge transfer resistance is tested at different temperatures and in different battery health states, and then a first preset corresponding relationship is obtained through a large amount of experimental data. Among them, the test battery and the battery to be monitored are from the same batch of batteries, and the parameters are the same, so the performance is the same. Therefore, the first preset corresponding relationship obtained based on the test battery is also applicable to the battery to be monitored.

[0066] When determining the charge transfer resistance of the battery to be monitored at a preset temperature, specifically: determine the size of the current first parameter of the battery to be monitored based on the current charge transfer resistance of the battery to be monitored, the current temperature and the first preset corresponding relationship; determine the charge transfer resistance of the battery to be monitored at the preset temperature based on the size of the current first parameter of the battery to be monitored and the preset temperature.

[0067] The current charge transfer resistance Rct0 and the current temperature T0 of the battery to be monitored are brought into the first preset corresponding relationship, and the size x0 of the first parameter corresponding to the battery to be monitored at the current moment is calculated, where x0=Rct0 / (T0*exp(a / T0)). Since this embodiment is equivalent to mapping the charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at the preset temperature T1, the size of the first parameter remains unchanged. Therefore, the charge transfer resistance Rct1=x0*T1*exp(a / T1) of the battery to be monitored at the preset temperature is obtained.

[0068] a is a setting constant, which can be obtained through a large number of experiments in the early stage. Specifically, the setting constant can be obtained by two methods, method 1 and method 2, as follows:

[0069] Method 1: Generate the charge transfer resistance corresponding to the test battery at different temperatures based on the Nyquist curve data at at least two different temperatures when the test battery is at a preset remaining power; calculate the set constant based on the charge transfer resistance corresponding to the test battery at at least two different temperatures.

[0070] Exemplarily, the preset remaining capacity can be SOC=75%, and the Nyquist curve data of the remaining capacity SOC=75% of the test battery at temperatures of 0°C, 25°C, and 50°C can be obtained, and the corresponding charge transfer resistance is calculated according to the corresponding Nyquist curve data at the above temperatures. Substitute the charge transfer resistance corresponding to 0°C into the first preset corresponding relationship to obtain the first equation: Rct3=x1*T2*exp(a / T2), where T2 is 0°C and Rct3 is the charge transfer resistance corresponding to the test battery at 0°C. Substitute 25°C into the first preset corresponding relationship to obtain the second equation: Rct4=x1*T3*exp(a / T3), where T3 is 25°C and Rct4 is the charge transfer resistance corresponding to the test battery at 25°C. Compare the first equation with the second equation to obtain the size of the set constant a. Among them, the health state of the battery will not change in a short time, so when the Nyquist curve data of the battery to be tested is obtained at the above-mentioned different temperatures, the health state of the battery to be tested is fixed, and the first parameter is a parameter related to the health state. When the health state does not change, the size of the first parameter does not change, which provides a premise for the above-mentioned calculation process of setting the constant a.

[0071] Method 2: Obtain correction coefficients of at least two test batteries, and determine a set constant based on the correction coefficients of each test battery; for any test battery, obtaining the correction coefficient of the test battery includes: generating a charge transfer resistance corresponding to the test battery at different temperatures based on Nyquist curve data at at least two different temperatures when the test battery is at a preset remaining power; and calculating a set constant corresponding to the test battery based on the charge transfer resistance corresponding to the test battery at at least two different temperatures as the correction coefficient of the test battery.

[0072] Optionally, the average value of the correction coefficients of each test battery is used as the set constant. For any test battery, its correction coefficient is the set constant calculated by the test battery in method 1, and the average value of the set constants obtained by each test battery is used as the set constant of the battery to be monitored, that is, the set constant in the first preset corresponding relationship.

[0073] As described above, a test battery can be selected and the set constants obtained from the Nyquist curve data of the test battery at different temperatures can be used as the set constants of the battery to be monitored to reduce the amount of calculation; the average value of the set constants of multiple test batteries can also be used as the set constants of the battery to be monitored to improve the accuracy of determining the set constants of the battery to be monitored, thereby improving the accuracy of subsequent determination of the health status of the battery to be monitored.

[0074] S131: When there is a reference charge transfer resistor among the multiple charge transfer resistors included in the second preset corresponding relationship, the health state corresponding to the reference charge transfer resistor is used as the current health state of the battery to be monitored; the reference charge transfer resistor is equal to the charge transfer resistance of the battery to be monitored at a preset temperature; when there is no reference charge transfer resistor among the multiple charge transfer resistors included in the second preset corresponding relationship, the current health state of the battery to be monitored is determined by interpolation calculation.

[0075] The second preset correspondence may be a preset correspondence table, the rows in the table may be charge transfer resistors, and the columns in the table may be health states corresponding to the charge transfer resistors. Exemplarily, the second preset correspondence includes multiple groups of binding point data groups, each binding point data group includes a binding point charge transfer resistor and a binding point health state corresponding to the charge transfer resistor, wherein different binding point data groups correspond to different binding point charge transfer resistors. Exemplarily, the second preset correspondence includes a first binding point data group, a second binding point data group, and a third binding point data group, the first binding point data group includes a first binding point charge transfer resistor and a first binding point health state, the second binding point data group includes a second binding point charge transfer resistor and a second binding point health state, the third binding point data group includes a third binding point charge transfer resistor and a third binding point health state, and the first binding point charge transfer resistor, the second binding point charge transfer resistor, and the third binding point charge transfer resistor increase in sequence.

[0076] If the charge transfer resistance of the battery to be monitored at the preset temperature is equal to the second binding point charge transfer resistance, the second binding point health state corresponding to the second binding point charge transfer resistance is used as the health state of the battery to be monitored. If the charge transfer resistance of the battery to be monitored at the preset temperature is not equal to any binding point charge transfer resistance, the health state corresponding to the charge transfer resistance of the battery to be monitored at the preset temperature is calculated by linear interpolation based on the two binding point charge transfer resistances adjacent to the charge transfer resistance at the preset temperature. If the charge transfer resistance of the battery to be monitored at the preset temperature is between the first binding point charge transfer resistance and the second binding point charge transfer resistance, the current health state of the battery to be monitored is determined by linear interpolation based on the first binding point data group and the second binding point data group.

[0077] The health status included in the second preset corresponding relationship is recorded as the binding point health status, and before S130 or S131, the following is further included:

[0078] According to the Nyquist curve data corresponding to the health status of each binding point when the test battery is at a preset remaining power, a preset temperature and in a static state, the charge transfer resistance corresponding to each binding point health state is determined; the health status of each binding point and its corresponding charge transfer resistance constitute a second preset corresponding relationship.

[0079] The preset temperature is set to room temperature 25°C, and the preset remaining power is set to SOC=75%. The Nyquist curve data of the health status of each binding point under the conditions of temperature 25°C and SOC=75% are obtained. For the Nyquist curve data corresponding to the health status of each binding point, the charge transfer resistance corresponding to the health status of the binding point is obtained according to the Nyquist curve data, and then the second preset corresponding relationship is obtained.

[0080] Among them, for the test battery, it is necessary to determine the health status of different binding points of the battery in advance. Determining the health status of any binding point includes:

[0081] The test battery is fully charged and discharged to obtain the current remaining capacity of the test battery; the health status of the binding point of the test battery is determined based on the current remaining capacity of the test battery and the initial remaining capacity, and the ratio of the current remaining capacity of the test battery to the initial remaining capacity can be further used as the size of the health status of the binding point of the test battery. The size of the health status of multiple test batteries at different stages is tested in advance through the ratio of the current remaining capacity and the initial remaining capacity, and it is used as the binding point health status. Among them, the initial remaining capacity can be understood as the remaining capacity of the test battery before leaving the factory, that is, the remaining capacity before it is put into use.

[0082] After determining the current health status of the battery to be monitored, the current health status can be converted into a score for the convenience of user observation, so that the user can more intuitively understand the current usage and life of the battery to be monitored. Before S11O or S111, the health status included in each second preset correspondence is scored to represent the different states of the battery, such as 100% for a health status of 100 points, 70% for a health status of 0 points, and the middle scores are evenly distributed. 60 points is a passing score, corresponding to a health status of 82%. Batteries with an average score of less than 60 points need to be replaced to remind the user in real time.

[0083] Figure 5 A schematic diagram of another device for online monitoring of battery health status provided by an embodiment of the present invention, referring to Figure 5 , the device comprises:

[0084] A current charge transfer resistance determination module 10, used to determine the current charge transfer resistance of the battery to be monitored according to multiple sets of Nyquist curve data at the current temperature of the battery to be monitored;

[0085] A preset charge transfer resistance determination module 20, used to convert the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at the preset temperature;

[0086] The health status determination module 30 is used to determine the current health status of the battery to be monitored based on the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset correspondence; wherein the second preset correspondence includes multiple charge transfer resistors and the health status corresponding to each charge transfer resistor at a preset temperature.

[0087] The beneficial effects of the device for online monitoring of the battery health status provided in this embodiment are the same as the beneficial effects of the method for online monitoring of the battery health status, which will not be repeated here.

[0088] Optionally, the preset charge transfer resistance determination module includes:

[0089] A preset charge transfer resistance determination unit, used to determine the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature;

[0090] The first preset corresponding relationship is the corresponding relationship between the charge transfer resistance and the temperature of the battery to be monitored, and the first preset corresponding relationship satisfies:

[0091] Rct=x*T*exp(a / T), wherein Rct is the charge transfer resistance, x is the first parameter related to the health status, T is the temperature, and a is the set constant.

[0092] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0093] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for online monitoring of the health status of a battery, characterized in that: include: When it is determined that the battery to be monitored meets the preset condition, the current charge transfer resistance of the battery to be monitored is determined according to the Nyquist curve data of the battery to be monitored at the current temperature; Converting the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at a preset temperature; The current health status of the battery to be monitored is determined based on the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset correspondence; wherein the second preset correspondence includes, at a preset temperature, multiple charge transfer resistors and the health status corresponding to each of the charge transfer resistors.

2. The method for online monitoring of battery health status according to claim 1, characterized in that: The step of converting the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at the preset temperature comprises: Determining the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature; The first preset corresponding relationship is the corresponding relationship between the charge transfer resistance and the temperature of the battery to be monitored, and the first preset corresponding relationship satisfies: Rct=x*T*exp(a / T), wherein Rct is the charge transfer resistance, x is the first parameter related to the health status, T is the temperature, and a is the set constant.

3. The method for online monitoring of battery health status according to claim 2, characterized in that: Before determining the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature, the method further includes: Generate charge transfer resistances corresponding to the test battery at different temperatures according to Nyquist curve data at at least two different temperatures when the test battery is at a preset remaining power; The set constant is calculated based on the charge transfer resistance corresponding to the test battery at at least two different temperatures.

4. The method for online monitoring of battery health status according to claim 2, characterized in that: Before determining the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature, the method further includes: Obtaining correction coefficients of at least two test batteries, and determining the set constant according to the correction coefficients of each of the test batteries; For any of the test batteries, obtaining a correction factor of the test battery includes: Generate charge transfer resistances corresponding to the test battery at different temperatures according to Nyquist curve data at at least two different temperatures when the test battery is at a preset remaining power; According to the charge transfer resistance corresponding to the test battery at at least two different temperatures, a set constant corresponding to the test battery is calculated and used as a correction coefficient of the test battery.

5. The method for online monitoring of battery health status according to claim 1, characterized in that: Determining the current health state of the battery to be monitored according to the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset corresponding relationship includes: When there is a reference charge transfer resistor among the multiple charge transfer resistors included in the second preset corresponding relationship, the health state corresponding to the reference charge transfer resistor is used as the current health state of the battery to be monitored; the reference charge transfer resistor is equal to the charge transfer resistance of the battery to be monitored at a preset temperature; When there is no reference charge transfer resistor among the multiple charge transfer resistors included in the second preset corresponding relationship, the current health state of the battery to be monitored is determined by interpolation calculation.

6. The method for online monitoring of battery health status according to claim 1, characterized in that: The health state included in the second preset corresponding relationship is recorded as the binding point health state, and before determining the current health state of the battery to be monitored according to the charge transfer resistance of the battery to be monitored at the preset temperature and the second preset corresponding relationship, the method further includes: Determine the charge transfer resistance corresponding to the health state of each binding point according to the Nyquist curve data corresponding to the health state of each binding point at the preset remaining power of the test battery and the preset temperature; The health status of each of the binding points and its corresponding load transfer resistance constitute the second preset corresponding relationship.

7. The method for online monitoring of battery health status according to claim 6, characterized in that: For the test battery, determining the health status of any of the binding points includes: Completely charging and discharging the test battery to obtain the current remaining power of the test battery; The binding point health status of the test battery is determined according to the current remaining power of the test battery and the initial remaining power of the test battery.

8. The method for online monitoring of battery health status according to claim 1, characterized in that: The preset conditions include: The battery to be monitored is in a static state within a preset time, and the remaining power of the battery to be monitored is between 20% and 80%; wherein, in the static state, the current value of the battery to be monitored is less than or equal to the current setting value.

9. A device for online monitoring of battery health status, characterized in that: include: A current charge transfer resistance determination module, used to determine the current charge transfer resistance of the battery to be monitored according to the Nyquist curve data of the battery to be monitored at the current temperature when it is determined that the battery to be monitored meets the preset conditions; A preset charge transfer resistance determination module, used to convert the current charge transfer resistance of the battery to be monitored at the current temperature to the charge transfer resistance at a preset temperature; A health status determination module is used to determine the current health status of the battery to be monitored based on the charge transfer resistance of the battery to be monitored at a preset temperature and a second preset correspondence; wherein the second preset correspondence includes, at a preset temperature, multiple charge transfer resistors and the health status corresponding to each of the charge transfer resistors.

10. The device for online monitoring of battery health status according to claim 9, characterized in that: The preset charge transfer resistance determination module includes: a preset charge transfer resistance determining unit, configured to determine the charge transfer resistance of the battery to be monitored at a preset temperature according to the first preset corresponding relationship, the current charge transfer resistance of the battery to be monitored, and the current temperature; The first preset corresponding relationship is the corresponding relationship between the charge transfer resistance and the temperature of the battery to be monitored, and the first preset corresponding relationship satisfies: Rct=x*T*exp(a / T), wherein Rct is the charge transfer resistance, x is the first parameter related to the health status, T is the temperature, and a is the set constant.

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