Method and apparatus for estimating battery charge state in a battery system

Abstract

The present invention provides a method and apparatus for estimating the charge state of a battery in a battery system, wherein the charge state of a replacement module is obtained, and the charge state of a main circuit battery is obtained through the charge state of the replacement module; the replacement module is used to replace the original battery, the capacity of the replacement module is greater than the capacity of the original battery, and the original battery is connected in series with the main circuit battery in the lithium iron phosphate battery branch circuit of the battery system; self-discharge detection is performed on the replacement module and the main circuit battery, and if the self-discharge is large in the self-discharge detection result, balance control is performed; after balance control, the updated charge state of the replacement module is determined, and the charge state of the main circuit battery is updated based on the updated charge state of the replacement module. The present invention improves the accuracy of estimating the charge state of the main circuit battery and expands the estimation range of the SOC of the main circuit battery, thereby improving the stability of the battery system.

Description

Technology Field

[0001] The present invention relates to battery technology, and more specifically, to a method and apparatus for estimating the battery charge state in a battery system. Background Technology

[0002] Chinese invention patent document Publication No. CN114545256A discloses a method and system for estimating the charge state of a lithium iron phosphate battery. This involves replacing one of the original batteries in the main circuit with a replacement module having a larger capacity than the main circuit battery, and designating the charge state of the replacement module as X. First, the charge states of the replacement module and the main circuit battery are adjusted so that both match at the SOC 0% state. As can be seen from the series connection relationship, during the subsequent charge-discharge process, the estimated charge state of the main circuit is X*A / B, where A is the capacity of the replacement module and B is the battery capacity of the main circuit. According to the charge-discharge voltage curve characteristics of the lithium iron battery, the battery voltage changes relatively distinctly depending on the charge state in the SOC 0%~30% and SOC 90%~100% ranges, so this can be used for estimating the charge state.

[0003] Even though the aforementioned technical solution has expanded the estimation range of the main circuit's charge state, if there is a large self-discharge between the replacement module or the main circuit battery, it can cause a significant error in the estimation of the charge state and make the estimation results of the lithium iron phosphate battery charge state inaccurate.

[0004] Taking into account the disadvantages of the aforementioned prior art, the objective of the present invention is to provide a method and apparatus for estimating the battery charge state in a battery system, thereby resolving the problem of inaccuracy in the estimation results of the lithium iron phosphate battery charge state in the prior art.

[0005] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for estimating the battery charge state in a battery system, comprising at least the following steps:

[0006] The lithium iron phosphate battery branch circuit of the battery system includes a primary battery and a main circuit battery connected in series, and a step of replacing the primary battery with a replacement module having a larger capacity than the primary battery;

[0007] A step of obtaining the charge state of the replacement module described above, and obtaining the charge state of the main circuit battery through the charge state of the replacement module;

[0008] A step of performing self-discharge detection for the aforementioned replacement module and the aforementioned main circuit battery, respectively, according to the charge state and battery health state of the aforementioned replacement module and the aforementioned main circuit battery, and, if there is a large self-discharge in the aforementioned replacement module or the aforementioned main circuit battery, performing balance control for the aforementioned replacement module and the aforementioned main circuit battery;

[0009] A step of determining the updated charging state of the replacement module after balance control, and updating the charging state of the main circuit battery described above based on the updated charging state of the replacement module described above.

[0010] Preferably, the step of performing self-discharge detection for the replacement module and the main circuit battery, respectively, based on the charge state of the replacement module and the main circuit battery described above, is

[0011] It includes performing self-discharge detection when the charge state of both the replacement module and the main circuit battery is in a low charge state range or when the charge state of the main circuit battery is in a high charge state range.

[0012] Preferably, the low charge state range is 0% to 30%, and the high charge state range is 90% to 100%.

[0013] Preferably, the step of performing balance control for the replacement module and the main circuit battery described above includes transferring a portion of the energy from the battery with a small self-discharge among the replacement module or the main circuit battery described above to the battery with a large self-discharge.

[0014] Preferably, the step of performing balance control for the replacement module and the main circuit battery described above includes discharging the energy of the battery with the smaller self-discharge among the replacement module or the main circuit battery described above through a resistor.

[0015] Preferably, a proportional conversion method is adopted to estimate and obtain the charge state of the main circuit battery based on the charge state of the replacement module or the updated charge state.

[0016] Preferably, before the step of performing self-discharge detection for the replacement module and the main circuit battery respectively, depending on the charge state and battery health state of the replacement module and the main circuit battery described above:

[0017] A step of determining the battery health status of the replacement module described above and the battery health status of the main circuit battery described above;

[0018] The method further includes the step of determining the current capacity of the replacement module described above using the battery health status of the replacement module described above, and determining the current capacity of the main circuit battery using the battery health status of the main circuit battery described above.

[0019] Preferably, when self-discharge is detected, if the charge state of the main circuit battery is not equal to the charge state of the replacement module n times, it is determined that a significant self-discharge has occurred in the replacement module or the main circuit battery; where n is the ratio of the current capacity of the replacement module to the current capacity C2 of the main circuit battery, the aforementioned current capacity of the replacement module is the product of the initial capacity of the replacement module and the battery health state of the replacement module, and the aforementioned current capacity of the main circuit battery is the product of the initial capacity of the main circuit battery and the battery health state of the main circuit battery.

[0020] Preferably, the balance control result ensures that the charge state of the main circuit battery is equal to the charge state of n times the replacement module.

[0021] To achieve the aforementioned purpose and other related purposes, the present invention further provides an apparatus for estimating the battery charge state in a battery system, wherein the apparatus comprises a memory, a processor, and a program stored in the aforementioned memory and operable on the aforementioned processor, and when the aforementioned processor executes the aforementioned program, the steps of the method for estimating the battery charge state in the aforementioned battery system are implemented.

[0022] As described above, the method and device for estimating the battery charge state in the battery system of the present invention have the following beneficial effects:

[0023] The method for estimating the battery charge state in the battery system of the present invention performs self-discharge detection and balance control on the existing estimated charge state. The charge state of the main circuit battery obtained by estimating through the updated charge state after balance control prevents interference caused by large self-discharges of the replacement module or the main circuit battery, improves the accuracy of the main circuit battery charge state estimation, and further enhances the stability of the battery system by expanding the estimation range of the main circuit battery's SOC. Brief explanation of the drawing

[0024] The features and performance of the present invention are further explained through the following examples and accompanying drawings. Figure 1 is a schematic diagram of the change in the charging voltage curve of the lithium iron phosphate battery of the present invention. Figure 2 is a schematic flowchart of a method for estimating the battery charge state in a battery system of the present invention. FIG. 3 is a schematic diagram of the structure of a battery charge state estimation device in a battery system of the present invention. Specific details for implementing the invention

[0025] The following describes the method of implementing the present invention through specific embodiments. Those skilled in the art can easily understand the other advantages and benefits of the present invention through the contents disclosed in this specification. The present invention may be implemented or applied in other different specific embodiments, and each detail in this specification may be subject to various modifications or changes according to different perspectives and applications, provided that such modifications do not contradict the spirit of the present invention.

[0026] Refer to FIGS. 1 to 3. It should be noted that the drawings provided in this embodiment are merely intended to explain the basic concept of the present invention in a schematic manner, that is, only components related to the present invention are shown in the drawings and are not drawn according to the number, shape, and size of the components in actual implementation, and that the shape, quantity, and ratio of each component in actual implementation may be changed at will, and the arrangement of the components may also become more complex.

[0027] As shown in Fig. 1, the change in the 0.1C charging voltage curve of a lithium iron phosphate battery at 25°C is schematic. According to Fig. 1, within the range of SOC 30% to 90%, the change in voltage according to SOC is not distinct, which increases the difficulty of SOC estimation; on the other hand, within the detection ranges of SOC 0% to 30% and SOC 90% to 100%, the change in voltage according to the charging state is relatively distinct, so in both of these ranges, the charging state can be estimated through voltage characteristics, and the estimation is relatively accurate.

[0028] In order to resolve the technical defect in the prior art where a relatively large error occurs in the estimation of the charge state when there is a large self-discharge between the replacement module or the main circuit battery, and consequently the estimation result of the lithium iron phosphate battery charge state becomes inaccurate, the present invention provides means to increase self-discharge detection and balance control in the case of a low charge state (where the charge state of both the replacement module and the main circuit battery is less than 30%) and the case of a high charge state (where the charge state of the main circuit battery is more than 90%), thereby improving the accuracy of the charge state estimation of the lithium iron phosphate battery and expanding the range of the charge state estimation of the lithium iron phosphate battery, and further improving the stability of the battery system.

[0029] Method Example:

[0030] The method for estimating the battery charge state in a battery system presented in the present invention includes at least the following contents, as illustrated in FIG. 2.

[0031] In an embodiment of the present invention, the initial capacity of the replacement module is C1', the initial capacity of the main circuit battery is C2', and C1' / C2'>1.

[0032] In step S1, the charge state of the replacement module is obtained, and the charge state of the main circuit battery is obtained through the charge state of the replacement module described above. The replacement module described above is intended to replace the original battery, and the capacity of the replacement module described above is greater than the capacity of the original battery described above. The original battery described above is connected in series with the main circuit battery described above in the lithium iron phosphate battery branch circuit of the battery system.

[0033] In the lithium iron phosphate battery branch circuit of the battery system of the present invention, the original battery and the main circuit battery are identical.

[0034] In the present invention, the replacement module is a replacement battery, and the replacement battery may adopt a lithium iron phosphate battery that has a relatively large difference from the original battery capacity and has a larger capacity than the original battery.

[0035] The present invention obtains the charge state of the main circuit battery by adopting a proportional conversion method based on the charge state of the replacement battery. Specifically, the charge state of the replacement battery is converted to the charge state of the main circuit battery using a proportional conversion method. Here, the greater the difference in capacity between the replacement battery and the main circuit battery, the wider the range of the estimated charge state becomes. Therefore, while the estimation becomes more accurate as the difference in capacity between the replacement battery and the main circuit battery increases, it cannot be practically applied if the difference is excessively large, as this leads to wasted costs.

[0036] In an embodiment of the present invention, the number of replacement batteries in the original battery and the replacement module is not limited, and the number of replacement batteries in the original battery and the replacement module may be the same or different; the number may be one or multiple, but if the number is multiple, multiple original batteries may be connected in series or parallel, and replacement batteries in the replacement module may also be connected in series or parallel, and it is sufficient to satisfy the requirement that the battery capacity of the replacement module is greater than the capacity of the original battery.

[0037] The present invention estimates and obtains the charge state of the main circuit battery by adopting a proportional conversion method based on the charge state of the replacement battery. Therefore, the charge state of the replacement module must first be obtained, and the proportional conversion method must be determined.

[0038] In the present invention, the charge state of the replacement module and the main circuit battery coincides at SOC 0%, and as can be seen based on the series connection relationship, the relationship between the charge state SOC_X of the main circuit battery and the charge state SOC_T of the replacement module during the subsequent charge / discharge process is as follows:

[0039] SOC_X=n×SOC_T

[0040] Here, the coefficient n' is the ratio of the initial capacity C1' of the replacement module to the initial capacity C2' of the main circuit battery, i.e., n' = C1' / C2'.

[0041] In an embodiment of the present invention, the method for obtaining the charge state of the replacement module is to estimate the charge state based on the voltage, the charge state of the replacement module is SOC_T, and the charge state of the main circuit battery is SOC_X = SOC_T × (C1' / C2').

[0042] In an embodiment of the present invention, as an example where n'=2, the replacement module is a lithium iron phosphate battery, and the initial capacity C1' of the replacement battery is twice the initial capacity C2' of the main circuit battery. As other embodiments, n' may also be a value of 1.5, 3, 4, etc.

[0043] In the initial state, both the replacement battery and the main circuit battery are in a state of 0% SOC, and since they are connected in series, the current passing through them during the subsequent charging and discharging process is the same. Therefore, when the charge state of the main circuit battery changes between 0% and 100%, the charge state of the replacement battery is exactly half of the charge state of the main circuit battery, which is 0% to 50%. When the replacement battery's SOC is within a more accurate detection range, for example, the detection range of the lithium iron phosphate battery's charge state from 0% to 30%, the SOC of the replacement battery can be estimated relatively accurately through the voltage, and the SOC of the main circuit battery (SOC 0% to 60%) can be obtained; in other ranges, the estimated SOC of the main circuit battery (for example, the SOC range of the lithium iron phosphate battery from 90% to 100%) is still used.

[0044] Therefore, when the charge state SOC_T of the replacement battery is SOC 0% to 30%, the charge state SOC_X of the main circuit battery is 2×SOC_T, and the estimation is relatively accurate. At this time, the charge state of the main circuit battery SOC 0% to 60% can be accurately estimated, and in the SOC 90% to 100% range, the SOC is still estimated using the voltage of the main circuit. Accordingly, the embodiments of the present application can extend the range where the charge state estimated according to voltage is accurate from SOC 0% to 30% and SOC 90% to 100% to SOC 0% to 60% and SOC 90% to 100%. The embodiments of the present application are merely examples and are not limited thereto.

[0045] In step S2, depending on the charge state of the replacement module and the main circuit battery described above, self-discharge detection is performed for the replacement module and the main circuit battery described above, respectively, and if there is a large self-discharge in the replacement module or the main circuit battery described above, balance control is performed for the replacement module and the main circuit battery described above.

[0046] Theoretically, since the charge states of the replacement module and the main circuit battery coincide at SOC 0%, the health state of the replacement module is assumed to be SOH1 and the health state of the main circuit battery is SOH2, with SOH1 / SOH2=1. As can be seen from the series connection relationship, the relationship between the charge state of the main circuit battery SOC_X and the charge state of the replacement module SOC_T during the subsequent charge-discharge process is as follows:

[0047] SOC_X=n×SOC_T

[0048] However, in reality, significant self-discharge occurs due to the influence of certain losses or other factors, which may prevent the relationship SOC_X = n × SOC_T from being maintained during subsequent charge-discharge processes. If the relationship of the charge state is not maintained, a very large error may occur in the charge state results estimated using this method; therefore, self-discharge detection and balance control must be performed on the replacement module and the main circuit battery to ensure the accuracy of the main circuit battery charge state SOC estimation.

[0049] In addition, since changes in the battery health status may cause a change in the coefficient n', the relationship between the main circuit battery's charge state SOC_X and the replacement module's charge state SOC_T must be re-established as follows:

[0050] SOC_X=n×SOC_T

[0051] Here, n is the ratio of the current capacity C1 of the replacement module to the current capacity of the main circuit battery, i.e., n = C1 / C2, where the current capacity of the replacement module is the product of the replacement module's initial capacity C1' and the replacement module's battery health state SOH1, and the current capacity of the main circuit battery is the product of the main circuit battery's initial capacity C2' and the main circuit battery's battery health state SOH2, and C1' > C2'.

[0052] It should be noted that when the initial time SOH1 / SOH2=1, n is the same as n' at the initial time.

[0053] The present invention updates the current capacity of the replacement module and the main circuit battery through the battery health status, reconfirms a new balance relationship between the charge state of the main circuit battery and the charge state of the replacement module, and finally performs a judgment based on the new balance relationship to improve the accuracy of the judgment regarding cases of large self-discharge.

[0054] Since self-discharge detection is performed for the replacement module and the main circuit battery respectively according to the charge state and battery health state of the replacement module and the main circuit battery described above, before performing self-discharge detection:

[0055] A step of determining the battery health status of the replacement module described above and the battery health status of the main circuit battery described above;

[0056] The method further includes the step of determining the current capacity of the replacement module described above using the battery health status of the replacement module described above, and determining the current capacity of the main circuit battery described above using the battery health status of the main circuit battery described above.

[0057] Here, the method for determining and obtaining the battery health status is a conventional technology, and is not described in detail in the embodiments of the present invention.

[0058] In one possible embodiment, when the charge state of both the replacement module and the main circuit battery is in a low charge state range or the charge state of the main circuit battery is in a high charge state range, self-discharge detection is performed, and balance control is performed when the self-discharge is large.

[0059] In an embodiment of the present invention, the low charge state range is 0% to 30%, and the high charge state range is 90% to 100%.

[0060] In the self-discharge detection process, the charge state of the replacement module is estimated and obtained based on the voltage of the replacement module or the ampere-hour integration method, and the charge state of the main circuit battery is estimated and obtained based on the voltage of the main circuit battery;

[0061] When the charge state of both the replacement module and the main circuit battery is in the low charge state range (0%~30%), self-discharge detection is performed, and it is determined whether there is a large self-discharge in the replacement module or the main circuit battery;

[0062] Specifically, the voltage-based estimated charge state SOC_X of the main circuit battery is less than 30%, and the voltage-based estimated charge state SOC_T of the replacement module is less than 30%, and:

[0063] If SOC_X > n×SOC_T, it is determined that a large self-discharge has occurred in the replacement module; if SOC_X < n×SOC_T, it is determined that a large self-discharge has occurred in the main circuit battery;

[0064] If SOC_X = n × SOC_T, it is determined that no significant self-discharge phenomenon occurred in either the replacement module or the main circuit battery.

[0065] When the charge state of the main circuit battery is in the high charge state range (90%~100%), self-discharge detection is performed, and the replacement module or main circuit battery determines whether there is a large self-discharge;

[0066] Specifically, the voltage-based estimated main circuit battery charge state SOC_X is greater than 90%, and the replacement module charge state is less than 50%, and:

[0067] If SOC_X > n×SOC_T, it is determined that a large self-discharge has occurred in the replacement module; if SOC_X < n×SOC_T, it is determined that a large self-discharge has occurred in the main circuit battery;

[0068] When SOC_X = n × SOC_T, no significant self-discharge occurred in either the replacement module or the main circuit battery.

[0069] As can be seen from the characteristic curves of voltage and charge state, between 30% and 60%, the change in voltage according to SOC is not distinct, so the estimation of SOC according to voltage can easily lead to a relatively large deviation. Therefore, according to other methods among the conventional technology, the charge state can be estimated and obtained by, for example, by the ampere-hour integration method.

[0070] Depending on the phenomenon of large self-discharge present in the self-discharge detection, balance control is performed to ensure that SOC_X = n × SOC_T is achieved again, thereby guaranteeing the estimation accuracy of the charge state of the subsequent main circuit battery.

[0071] In another preferred embodiment of the present invention, considering that absolute balance is difficult to maintain stably during the balance control process, in actual applications, it may be considered to determine whether the self-discharge is large by allowing a certain deviation based on the judgment conditions of the embodiments of the present invention. Here, the deviation may be a deviation magnitude (a single value or an interval) or a certain ratio value.

[0072] Specifically, for example, regardless of whether it is a low-charge state or a high-charge state, if SOC_X > n × SOC_T + δ, it is determined that a large self-discharge has occurred in the replacement module; if SOC_X < n × SOC_T - δ, it is determined that a large self-discharge has occurred in the main circuit battery; and if SOC_X = n × SOC_T ± δ, it is determined that no large self-discharge phenomenon has occurred in either the replacement module or the main circuit battery; δ indicates the magnitude of the deviation. In the embodiments of the present application, specific limitations are not placed on the specific numerical value or range of δ, and it can be specifically selected according to the actual situation.

[0073] In an embodiment of the present invention, if there is a case where the self-discharge of the replacement module or the main circuit battery described above is large, it means that the other self-discharge is small, and the balance control of the present invention is active balance or passive balance. Active balance refers to transferring the battery energy with small self-discharge from the replacement module or the main circuit battery described above to the battery with large self-discharge; passive balance refers to discharging the battery energy with small self-discharge among the replacement module or the main circuit battery described above through a resistor.

[0074] The present invention readjusts the relationship between the charge states of the replacement module and the main circuit battery through balance control, thereby ensuring the accuracy of the charge state of the main circuit battery obtained according to the updated charge state of the replacement module.

[0075] In step S3, the updated charging state of the replacement module is determined after balance control, and the charging state of the main circuit battery described above is updated according to the updated charging state of the replacement module described above.

[0076] After performing balance control on the battery of the lithium iron phosphate battery branch circuit of the battery system, the updated charge state of the replacement module is determined, and the method of the next step S1 is adopted, that is, by adopting a proportional conversion method based on the updated charge state of the replacement module, the updated charge state of the main circuit battery is estimated and obtained, and the charge state of the main circuit battery is updated through the updated charge state of the main circuit battery to obtain a main circuit charge state of higher accuracy.

[0077] Here, determining the updated charge state of the replacement module is as follows: if the charge state of the replacement module does not change during the balance control process, the updated charge state is the original charge state; if the charge state of the replacement module changes during the balance control process, the charge state of the replacement module must be re-acquired or calculated to determine the updated charge state. However, in actual applications, if the balance control time is prolonged, the charge state of the replacement module may change regardless of whether it is designated as a balance control target; in this case, the updated charge state of the replacement module must always be a newly acquired charge state.

[0078] Specifically, the updated charge state of the main circuit battery is estimated and obtained by adopting a proportional conversion method based on the updated charge state of the replacement module. The updated charge state of the main circuit battery, which is the charge state of the main circuit battery, and the charge state obtained by estimating it through the updated charge state after balance control, prevented interference caused by large self-discharge of the replacement module or the main circuit battery, improved the accuracy of the main circuit battery charge state estimation, expanded the estimation range of the main circuit battery's SOC, and further enhanced the stability of the battery system.

[0079] Device Example:

[0080] A schematic diagram of the structure of a battery charge state estimation device in a battery system provided by the present invention is as shown in FIG. 3, and the device includes a memory, a processor, and a program stored in the memory and operable on the processor, and when the processor executes the program, it implements the steps of a method for estimating the battery charge state in a battery system.

[0081] The detailed process of the steps of the method for estimating the battery charge state in a battery system has been introduced in detail in the method examples and is not described in detail here.

[0082] In summary, regarding the method and apparatus for estimating the battery charge state in a battery system according to the present invention, the method for estimating the battery charge state in a battery system performs self-discharge detection and balance control on a previously estimated charge state. The charge state of the main circuit battery obtained by estimating through the updated charge state after balance control prevents interference caused by large self-discharges of the replacement module or the main circuit battery, improves the accuracy of estimating the main circuit battery charge state, and further enhances the stability of the battery system by expanding the estimation range of the main circuit battery's SOC. Therefore, the present invention effectively overcomes various drawbacks of the prior art and possesses high industrial application value.

[0083] The embodiments described above are intended only to illustratively explain the principles and efficacy of the present invention and are not intended to limit the invention. Any person skilled in the art may modify or change the embodiments described above, provided that such modifications do not contradict the spirit and scope of the present invention. Accordingly, modifications and changes made by a person of ordinary skill in the art, provided they do not contradict the disclosed spirit and technical spirit of the present invention, are still included within the claims of the present invention.

Claims

Claim 1 A method for estimating the battery charge state in a battery system comprises: a step of obtaining the charge state of a replacement module and obtaining the charge state of a main circuit battery through the charge state of the replacement module, wherein the replacement module is used to replace the original battery, the capacity of the replacement module is greater than the capacity of the original battery, and the original battery is connected in series with the main circuit battery in a lithium iron phosphate battery branch circuit of the battery system; a step of performing self-discharge detection on the replacement module and the main circuit battery, respectively, according to the charge state and battery health state of the replacement module and the main circuit battery, and, if there is a large self-discharge in the replacement module or the main circuit battery, performing balance control on the replacement module and the main circuit battery, wherein the result of the balance control is such that the charge state of the main circuit battery is equal to n times the charge state of the replacement module, where n is the ratio of the current capacity of the replacement module to the current capacity of the main circuit battery; and at least a step of determining the updated charge state of the replacement module after balance control and updating the charge state of the main circuit battery according to the updated charge state of the replacement module. A method for estimating the battery charge state in a battery system, characterized by the following. Claim 2 A method for estimating the battery charge state in a battery system, wherein, in claim 1, the step of performing self-discharge detection for the replacement module and the main circuit battery, respectively, according to the charge state of the replacement module and the main circuit battery, includes performing self-discharge detection when the charge state of both the replacement module and the main circuit battery is in a low charge state range or when the charge state of the main circuit battery is in a high charge state range. Claim 3 A method for estimating the battery charge state in a battery system, characterized in that, in paragraph 2, the low charge state range is 0% to 30% and the high charge state range is 90% to 100%. Claim 4 A method for estimating the battery charge state in a battery system, wherein, in claim 1, the step of performing balance control for the replacement module and the main circuit battery includes transferring a portion of the battery energy with a small self-discharge among the replacement module or the main circuit battery to the battery with a large self-discharge. Claim 5 A method for estimating the battery charge state in a battery system, wherein, in claim 1, the step of performing balance control for the replacement module and the main circuit battery includes consuming the battery energy of the replacement module or the main circuit battery with a small self-discharge through a resistor. Claim 6 A method for estimating the battery charge state in a battery system, characterized in that, in claim 1, a proportional conversion method is adopted to estimate and obtain the charge state of the main circuit battery according to the charge state of the replacement module or the updated charge state. Claim 7 A method for estimating a battery charge state in a battery system, characterized by further including, prior to the step of performing self-discharge detection for the replacement module and the main circuit battery respectively according to the charge state and battery health state of the replacement module and the main circuit battery, a step of determining the battery health state of the replacement module and the battery health state of the main circuit battery; a step of determining the current capacity of the replacement module using the battery health state of the replacement module and determining the current capacity of the main circuit battery using the battery health state of the main circuit battery. Claim 8 A method for estimating the battery charge state in a battery system, characterized in that, in claim 7, when self-discharge is detected, if the charge state of the main circuit battery is not equal to the charge state of the replacement module n times, it is determined that a large self-discharge has occurred in the replacement module or the main circuit battery; and the current capacity of the replacement module is the product of the initial capacity of the replacement module and the battery health state of the replacement module, and the current capacity of the main circuit battery is the product of the initial capacity of the main circuit battery and the battery health state of the main circuit battery. Claim 9 An estimation device for a battery charge state in a battery system, comprising a memory, a processor, and a program stored in the memory and operable on the processor, wherein when the processor executes the program, the step of the method for estimating a battery charge state in a battery system according to any one of claims 1 to 8 is implemented. Claim 10 delete

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