Calculation Method for State of Charge of Battery

Abstract

The present disclosure relates to a method for calculating the state of charge of a battery. The method for calculating the state of charge of a battery according to the present disclosure includes: estimating a first state of charge of the battery using a first state-of-charge estimation method; estimating a second state of charge of the battery using a second state-of-charge estimation method; determining a first weight corresponding to the first state of charge and a second weight corresponding to the second state of charge according to the state data of the battery; and calculating the state of charge of the battery based on the first state of charge and the first weight and the second state of charge and the second weight. The method for calculating the state of charge of a battery according to the present disclosure can improve the calculation accuracy of the state of charge of the battery at a relatively low calculation cost.

Description

Technical Field

[0001] The present disclosure generally relates to the technical field of batteries, and more specifically, to a method for calculating the state of charge of a battery with higher accuracy at a lower computational cost by combining different state of charge estimation methods. Background Art

[0002] In the management system of a battery as an energy storage device, the state of charge (SOC) of the battery is a core state, which affects the state of health (SOH), state of energy (SOE), state of power (SOP) of the battery, and even affects battery safety. However, due to the complex environment where the battery is located and too many influencing parameters, it is difficult to accurately predict the state of charge of the battery.

[0003] During the charge and discharge process of, for example, a lithium iron phosphate battery, when the charge and discharge stop instantaneously and the current direction changes, the internal balance of the battery changes, and at the same time, the ohmic internal resistance, electrochemical polarization state, and concentration polarization state of the battery all change. This will cause the battery voltage to change rapidly at the instant of charge and discharge and take a long time to return to the equilibrium state again. During this process, the voltage change will cause a large error in the state of charge of the battery calculated based on battery parameters such as voltage and current. In addition, since the process of concentration polarization is relatively long and the concentration polarization parameters are also different under different state of charge conditions, this process will cause the calculated state of charge to fluctuate for a long time. Therefore, during the period from when the charge and discharge of the battery stops until the battery reaches a new equilibrium state, the measured terminal voltage of the battery cannot be considered as the open-circuit voltage of the battery.

[0004] The above changes mainly occur when the battery current suddenly changes, that is, the four cases where the current direction suddenly changes from positive to negative or from negative to positive, or the current changes from zero to non-zero or from non-zero to zero. When charging the battery with a constant current, this situation occurs less frequently and mainly occurs at the beginning and end of charging; when charging the battery with a frequency-modulated current, this situation occurs frequently and has a great impact.

[0005] Due to the above reasons, it is difficult to accurately estimate the state of charge of the battery when the battery current suddenly changes. Summary of the Invention

[0006] In order to solve the above problems existing in the prior art, the present disclosure proposes a method for calculating the state of charge of a battery.

[0007] The method for calculating the state of charge of a battery according to the present disclosure corrects the state of charge of the battery after the internal balance is broken based on the state data of the battery measured during the internal change process of the battery, and uses a mathematical method combined with different state of charge estimation methods of the battery to calculate the state of charge of the battery during the period when the internal balance of the battery is broken and returns to balance again.

[0008] A brief overview of the present disclosure will be given below in order to provide a basic understanding of certain aspects of the present disclosure. It should be understood that this overview is not an exhaustive overview of the present disclosure, nor is it intended to identify the key or important parts of the present disclosure or to limit the scope of the present disclosure. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description to be discussed later.

[0009] To achieve the object of the present disclosure, according to one aspect of the present disclosure, there is provided a method for calculating the state of charge of a battery, which includes: estimating a first state of charge of the battery using a first state of charge estimation method; estimating a second state of charge of the battery using a second state of charge estimation method; determining a first weight corresponding to the first state of charge and a second weight corresponding to the second state of charge according to the state data of the battery; and calculating the state of charge of the battery based on the first state of charge and the first weight and the second state of charge and the second weight.

[0010] According to an embodiment of the present disclosure, the first state of charge estimation method is an open circuit voltage method, and the second state of charge estimation method is an ampere-hour integration method.

[0011] According to an embodiment of the present disclosure, the first state of charge estimation method is a method based on a battery equivalent circuit model based on at least one of an R-int equivalent circuit model of the battery, a first-order RC equivalent circuit model, and a second-order RC equivalent circuit model.

[0012] According to an embodiment of the present disclosure, estimating a first state of charge of the battery using the first state of charge estimation method includes: establishing a state of charge model of the battery according to the historical charge and discharge data of the battery; sensing the current charge and discharge data of the battery; and estimating the first state of charge using the state of charge model based on the current charge and discharge data.

[0013] According to an embodiment of the present disclosure, the state of charge model is a charge and discharge curve fitted using historical charge and discharge data or a look-up table formed using historical charge and discharge data.

[0014] According to an embodiment of the present disclosure, the historical charge and discharge data and the current charge and discharge data include the current and / or voltage of the battery.

[0015] According to an embodiment of the present disclosure, determining a first weight corresponding to a first state of charge and a second weight corresponding to a second state of charge based on the state data of the battery includes: determining the current state of the battery according to historical charge and discharge data and current charge and discharge data; and determining the first weight and the second weight according to the current state.

[0016] According to an embodiment of the present disclosure, determining the current state includes: determining whether the battery enters a hysteresis state; and when it is determined that the battery enters the hysteresis state, determining the time when the battery is in the hysteresis state.

[0017] According to an embodiment of the present disclosure, determining the first weight and the second weight according to the current state includes: when it is determined that the battery enters the hysteresis state, reducing the first weight and / or increasing the second weight, and gradually reducing the first weight and / or increasing the second weight according to the time when the battery is in the hysteresis state.

[0018] According to an embodiment of the present disclosure, the battery is a lithium-ion battery or a sodium-ion battery.

[0019] According to the method for calculating the state of charge of the battery of the present disclosure, the calculation accuracy of the state of charge of the battery can be improved at a relatively small calculation cost. Description of the Drawings

[0020] Referring to the following description of the embodiments of the present disclosure in conjunction with the drawings, the above and other objects, features and advantages of the present disclosure will be more easily understood.

[0021] Figure 1 A flowchart showing a method for calculating the state of charge of a battery according to an embodiment of the present disclosure is shown.

[0022] Figure 2 A circuit diagram showing an R-int equivalent circuit model of the battery is shown.

[0023] Figure 3 A circuit diagram showing a first-order RC equivalent circuit model of the battery is shown.

[0024] Figure 4 A circuit diagram showing a second-order RC equivalent circuit model of the battery is shown.

[0025] Figure 5 A flowchart showing an example of a method for calculating the state of charge of a battery according to an embodiment of the present disclosure is shown. Detailed Embodiments

[0026] In the following, some embodiments of the present disclosure will be described in detail with reference to the accompanying illustrative drawings. When referring to the elements of the drawings by reference numerals, although the same elements are shown in different drawings, the same elements will be denoted by the same reference numerals. In addition, in the following description of the present disclosure, detailed descriptions of known functions and configurations incorporated herein will be omitted where possible so as not to obscure the subject matter of the present disclosure.

[0027] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. As used herein, unless the context otherwise indicates, the singular forms are also intended to include the plural forms. It will also be understood that the terms "comprises," "comprising," and "has" used in the specification are intended to specify the presence of the stated features, entities, operations, and / or components, but do not preclude the presence or addition of one or more other features, entities, operations, and / or components.

[0028] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0029] In the following description, numerous specific details are set forth to provide a thorough understanding of the present disclosure. The present disclosure may be practiced without some or all of these specific details. In other instances, in order to avoid obscuring the present disclosure with unnecessary details, only components closely related to the solution according to the present disclosure are shown in the drawings, while other details less related to the present disclosure are omitted.

[0030] In the following, a method for calculating the state of charge of a battery according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0031] Figure 1 is a flowchart showing a method 100 for calculating the state of charge of a battery according to an embodiment of the present disclosure. According to an embodiment of the present disclosure, the battery may be a lithium-ion battery or a sodium-ion battery. In particular, according to an embodiment of the present disclosure, the battery may be a lithium iron phosphate battery.

[0032] As Figure 1 shown, according to an embodiment of the present disclosure, the calculation method 100 may include:

[0033] Step 101, where a first state of charge SOC1 of the battery is estimated using a first state of charge estimation method;

[0034] Step 102, wherein a second state of charge SOC2 of the battery is estimated using a second state of charge estimation method;

[0035] Step 103, wherein a first weight α corresponding to a first state of charge SOC1 and a second weight β corresponding to a second state of charge SOC2 are determined according to the state data of the battery; and

[0036] Step 104 , wherein the state of charge of the battery is calculated based on the first state of charge SOC1 and the first weight α and the second state of charge SOC2 and the second weight β.

[0037] Each step 101 to step 104 is described in more detail below.

[0038] According to an embodiment of the present disclosure, in step 101, the first state of charge estimation method may be, for example, an open circuit voltage method or a method based on a battery equivalent circuit model.

[0039] The open circuit voltage method determines the state of charge based on the open circuit voltage (OCV) of the battery. Taking a lithium-ion single cell as an example, the open circuit voltage of the battery is generally about 4.2V when fully charged, and about 2.6V when fully discharged. During the charging and discharging process of the battery, the open circuit voltage of the battery changes continuously. Studies have found that there is a certain control relationship between the open circuit voltage of the battery and the state of charge of the battery. By fitting the data of the control relationship, the state of charge of the battery can be calculated based on the open circuit voltage of the battery. The advantage of using the open circuit voltage method as the first state of charge estimation method is that the amount of calculation used to estimate the state of charge can be reduced, and the calculation speed can be improved within a certain accuracy range. However, as mentioned above, due to the polarization effect in lithium-ion batteries, for example, the open circuit voltage of the battery is not constant for a period of time after charging and discharging stops, but changes slowly. Usually, the voltage measured after the battery has been left to stand for a period of time is the true open circuit voltage at the current state of charge. In addition, for example, the relationship between the open circuit voltage and the state of charge of a lithium-ion battery is greatly affected by the ambient temperature, so the first state of charge of the battery estimated by the open circuit voltage method still needs to be corrected. Since the open circuit voltage method is known to those skilled in the art, for the sake of brevity, the details of the open circuit voltage method are not described in more detail herein.

[0040] In addition, the method based on the battery equivalent circuit model uses circuit elements to physically model the battery to simulate the electrical characteristics of the battery. According to an embodiment of the present disclosure, the first state of charge estimation method is a method based on a battery equivalent circuit model based on at least one of the R-int equivalent circuit model, the first-order RC equivalent circuit model (Thevenin model) and the second-order RC equivalent circuit model of the battery. Figures 2 to 4, where Figure 2 is a circuit diagram showing the R-int equivalent circuit model of the battery, Figure 3 is a circuit diagram showing the first-order RC equivalent circuit model of the battery, and Figure 4 is a circuit diagram showing the second-order RC equivalent circuit model of the battery. In Figures 2 to 4 , UOC is a voltage source representing the open-circuit voltage of the battery; R0, R1, and R2 are resistors; C1 and C2 are capacitors; and U and I are the voltage and current of the battery, respectively. Since the above battery equivalent circuit models are known to those skilled in the art, for the sake of brevity, the details of these battery equivalent circuit models will not be described in more detail herein.

[0041] By adopting the equivalent circuit model, the state of charge of the battery can be calculated. In particular, compared with the R-int equivalent circuit model, the first-order RC equivalent circuit model and the second-order RC equivalent circuit model have more parameters, making the solution difficult. However, although the R-int equivalent circuit model is relatively simple, it considers too few situations, and when changes occur inside the battery, the calculation accuracy of the state of charge of the battery is insufficient, so further correction is still required.

[0042] According to an embodiment of the present disclosure, in step S101, a state-of-charge model of the battery can be established based on the historical charge and discharge data of the battery, the current charge and discharge data of the battery can be sensed, and the first state of charge SOC1 can be estimated using the state-of-charge model based on the current charge and discharge data.

[0043] Specifically, according to an embodiment of the present disclosure, in step S101, based on the historical charge and discharge data of the battery, the charge and discharge curve with the best operating conditions can be automatically selected. Subsequently, appropriate state data such as the charge and discharge voltage, equivalent internal resistance, and estimated open-circuit voltage can be extracted according to the corresponding historical charge and discharge data and the rated charge and discharge cut-off voltage, and based on this, a state-of-charge model of the battery can be established. According to an embodiment of the present disclosure, the state-of-charge model can be a charge and discharge curve fitted using historical charge and discharge data or a look-up table formed using historical charge and discharge data. More specifically, according to an embodiment of the present disclosure, the state-of-charge model can be a correspondence relationship between the historical charge and discharge data of the battery and the state of charge of the battery established using the first state-of-charge estimation method, such as the open-circuit voltage method or the method based on the battery equivalent circuit model. In addition, according to an embodiment of the present disclosure, the historical charge and discharge data can include the current and / or voltage of the battery.

[0044] According to an embodiment of the present disclosure, in step S101, after establishing the state-of-charge model of the battery, the battery can be powered on to sense the current charge and discharge data of the battery. Specifically, according to an embodiment of the present disclosure, sensors can be used to sense the current charge and discharge data of the battery, such as the current and / or voltage of the battery.

[0045] According to an embodiment of the present disclosure, in step S101, the first state of charge SOC1 can be estimated using a previously established state of charge model based on the sensed current charge and discharge data. For example, in the case where the state of charge model of the battery is established as a look-up table, the corresponding first state of charge SOC1 can be obtained by querying the look-up table based on the sensed current charge and discharge data.

[0046] For example, according to an embodiment of the present disclosure, the first state of charge SOC1 obtained in step S101 can be represented by the following formula (1).

[0047] SOC1 = f(U, I) (1)

[0048] Where f represents the state of charge model established in step S101.

[0049] Subsequently, according to an embodiment of the present disclosure, in step S102 of the calculation method 100, a second state of charge estimation method is used to estimate the second state of charge SOC2 of the battery. According to an embodiment of the present disclosure, the second state of charge estimation method can be, for example, the ampere-hour integration method.

[0050] The ampere-hour integration method integrates the charge and discharge current of the battery over time and calculates the state of charge of the battery at a certain moment thereafter based on the initial state of charge of the battery. Since the ampere-hour integration method is known to those skilled in the art, for the sake of brevity, the details of the ampere-hour integration method are not described in more detail herein.

[0051] For example, according to an embodiment of the present disclosure, the second state of charge SOC2 obtained in step S102 can be represented by the following formula (2).

[0052] SOC2 = SOC0 + (I × Δt) / C × 100% (2)

[0053] Where SOC0 represents the initial state of charge of the battery, Δt represents the time interval for integrating the battery current I over time, and C represents the battery capacity according to the degree of battery aging.

[0054] Subsequently, according to an embodiment of the present disclosure, in step 103 of the calculation method 100, a first weight α corresponding to the first state of charge SOC1 and a second weight β corresponding to the second state of charge SOC2 are determined based on the state data of the battery. According to an embodiment of the present disclosure, the first weight α corresponding to the first state of charge SOC1 may be used as the main weight, and the second weight β corresponding to the second state of charge SOC2 may be used as the secondary weight. When the battery is in certain specific states, the first state of charge SOC1 is corrected using the second state of charge SOC2 by adjusting the first weight α and the second weight β.

[0055] According to an embodiment of the present disclosure, in step S103, the current state of the battery may be determined based on the historical charge and discharge data and the current charge and discharge data of the battery, and then the first weight α and the second weight β may be determined based on the current state of the battery.

[0056] Specifically, according to an embodiment of the present disclosure, in step S103, when the current state of the battery determined based on the historical charge and discharge data and the current charge and discharge data of the battery is the static state, the state of charge of the battery may be kept unchanged.

[0057] In addition, according to an embodiment of the present disclosure, in step S103, determining the current state of the battery may include determining whether the battery enters the hysteresis state, and when it is determined that the battery enters the hysteresis state, the time when the battery is in the hysteresis state may be further determined.

[0058] In a battery such as a lithium iron phosphate battery, there is a hysteresis characteristic, that is, between the charging process and the discharging process of the battery, the correspondence between the state of charge of the battery and the open-circuit voltage is inconsistent. Therefore, when using the ampere-hour integration method as an example of the second state of charge estimation method to estimate the second state of charge SOC2 of the battery, due to the hysteresis characteristic of the battery, there may be a large error in the estimated second state of charge SOC2. Therefore, the error may be corrected by adjusting the first weight α corresponding to the first state of charge SOC1 and the second weight β corresponding to the second state of charge SOC2 in step S103. Specifically, according to an embodiment of the present disclosure, the state of charge model of the battery established in step S101 itself can reflect the influence of the hysteresis characteristic of the battery on the state of charge of the battery to a certain extent. Therefore, combining with the second state of charge SOC2, the first state of charge SOC1 determined in step S101 can have a certain correction ability.

[0059] Specifically, according to an embodiment of the present disclosure, in step S103, when it is determined that the current state of the battery is the working state based on the historical charge-discharge data and the current charge-discharge data of the battery, it can be determined whether the battery enters the hysteresis state. According to an embodiment of the present disclosure, when it is determined that the battery does not enter the hysteresis state, the first weight α and the second weight β can be maintained unchanged.

[0060] In addition, according to an embodiment of the present disclosure, when it is determined that the battery enters the hysteresis state, the first weight α is decreased and / or the second weight β is increased. In addition, according to an embodiment of the present disclosure, when it is determined that the battery enters the hysteresis state, the time for which the battery is in the hysteresis state can be further determined based on the historical charge-discharge data and the current charge-discharge data of the battery, and the first weight α and / or the second weight β can be gradually adjusted according to the time for which the battery is in the hysteresis state. For example, according to an embodiment of the present disclosure, when it is determined that the battery gradually changes from the working state (hysteresis state) to the stationary state, the first weight α can be gradually increased and / or the second weight β can be decreased until the hysteresis state ends and the battery enters the stationary state.

[0061] Subsequently, according to an embodiment of the present disclosure, in step 104 of the calculation method 100, the state of charge of the battery can be calculated based on the first state of charge SOC1, the first weight α, the second state of charge SOC2, and the second weight β. Specifically, according to an embodiment of the present disclosure, the state of charge of the battery can be calculated according to the following formula (3).

[0062] (α×SOC1 + β×SOC2) / (α + β) (3)

[0063] According to an embodiment of the present disclosure, the calculation method 100 may further include determining whether the battery is in a dangerous stage based on the calculated state of charge of the battery and the current charge-discharge data (such as voltage and / or current, etc.) of the battery, and issuing a safety or warning report accordingly.

[0064] The following Figure 5 shows an example for an exemplary description of the calculation method 100 described above with reference to Figure 1 the above. Figure 5 is a flowchart showing an example of a method for calculating the state of charge of a battery according to an embodiment of the present disclosure.

[0065] As Figure 5 shown, in step S101 of the calculation method 100 described above with reference to Figure 1 the above, first, a parameter set of the battery is obtained based on the historical charge-discharge data of the battery. The parameter set can be a state of charge model of the battery, such as a charge-discharge curve fitted using historical charge-discharge data or a look-up table formed using historical charge-discharge data. Subsequently, as Figure 5As shown, the battery is powered on to obtain the initial state of charge, the battery capacity, and the current charge and discharge data of the battery, such as the current current and voltage of the battery.

[0066] Next, as Figure 5 shown, as described in step S103 of calculation method 100 with reference to the above, determine the current state of the battery. When it is determined that the current state of the battery is the stationary state, that is, when it is determined that the battery has been stationary for a long time, the state of charge of the battery is maintained unchanged. Figure 1

[0067] Figure 5 In addition, as shown, when it is determined that the current state of the battery is the working state, determine whether the battery enters the hysteresis state according to the current current and voltage state of the battery, that is, the current charge and discharge data of the battery and the current and voltage state of the battery at the previous moment, that is, the historical charge and discharge data of the battery.

[0068] Figure 5 Next, as Figure 1 shown, as described in step S103 of calculation method 100 with reference to the above, when it is determined that the battery does not enter the hysteresis state, the current weights, that is, the first weight α and the second weight β, can be maintained, and the state of charge of the battery can be calculated accordingly.

[0069] Figure 5 In addition, as shown, when it is determined that the battery enters the hysteresis state, the weight coefficients, that is, the first weight α and the second weight β, can be adjusted according to the previous state, that is, the current and voltage state of the battery at the previous moment. In addition, as Figure 5 shown, when it is determined that the battery enters the hysteresis state, the time for the battery to be in the hysteresis state can be further determined according to the historical charge and discharge data and the current charge and discharge data of the battery, and the first weight α and / or the second weight β can be gradually adjusted according to the time for the battery to be in the hysteresis state. For example, when it is determined that the battery gradually changes from the working state (hysteresis state) to the stationary state, the first weight α can be gradually increased and / or the second weight β can be decreased.

[0070] Figure 5 Figure 1 Next, as shown, as described in step S102 of calculation method 100 with reference to the above, calculate the second state of charge of the battery using a second state-of-charge estimation method such as the ampere-hour integration method. At the same time, obtain the first state of charge of the battery using the previously established state-of-charge model of the battery.

[0071] Figure 5 Figure 1 ​​​​​In step S104 of the described calculation method 100, the state of charge of the battery is calculated using the first state of charge of the battery and its first weight, and the second state of charge of the battery and its second weight. Subsequently, the calculated state of charge of the battery can be output.

[0072] As Figure 5 shown, the steps after the step of determining the current state of the battery described above can be cyclically executed at a predetermined time interval. At this time, based on the charge and discharge data of the battery obtained at the next moment, such as the current and voltage of the battery, the above cycle is continued.

[0073] As an example, taking the historical data of a certain power station for a period of time as the parameter extraction set and the test set, using the calculation method of the battery state of charge according to the present disclosure as described above, after a period of adaptation, the error of the finally calculated battery state of charge can be less than 5%. Specifically, the average error of the battery state of charge is -2.265, and the mean square error is 9.673. As a comparison, if the ampere-hour integration method is used to calculate the battery state of charge, for the same parameter extraction set and test set, the average error of the calculated battery state of charge is -3.212, and the mean square error is 17.544. Obviously, the calculation accuracy of the calculation method of the battery state of charge according to the present disclosure is better than that of the ampere-hour integration method.

[0074] According to the calculation method of the battery state of charge according to the present disclosure, based on the change condition of the charge and discharge data such as current and voltage in the battery, a first state of charge estimation method, such as based on the R-int equivalent circuit model, can be used to establish a battery state of charge model, such as extracting a battery voltage-state of charge parameter curve. In addition, a second state of charge estimation method, such as the ampere-hour integration method, can be combined to correct the state of charge obtained by using the first state of charge estimation method when the internal state of the battery changes. Through an adaptive method, the weight ratio of the battery voltage-state of charge curve and the ampere-hour integration method can be adjusted, and the calculated state of charge can be corrected according to the current change in different situations, so as to obtain a more accurate battery state of charge.

[0075] Compared with the traditional open-circuit voltage method, the calculation method of the battery state of charge according to the present disclosure can omit the static experiment of measuring the relationship between the state of charge and the open-circuit voltage for a long time, and can solve the problem that the open-circuit voltage calculation is inaccurate when the battery current suddenly changes violently. In addition, compared with the ampere-hour integration method, the calculation method of the battery state of charge according to the present disclosure can eliminate the cumulative error of using the ampere-hour integration method for a long time.

[0076] In addition, compared with the Kalman filter, the calculation method of the battery state of charge according to the present disclosure can eliminate the lag of error prediction when mutations occur and disappear and the fluctuations in the stationary state.

[0077] Although the present disclosure has been disclosed above by the description of the specific embodiments of the present disclosure, it should be understood that those skilled in the art can design various modifications, improvements or equivalents to the present disclosure within the spirit and scope of the appended claims. These modifications, improvements or equivalents should also be considered to be included within the protection scope of the present disclosure.

Claims

1. A method for calculating the state of charge of a battery, comprising: estimating a first state of charge of the battery using a first state-of-charge estimation method; specifically including: establishing a state-of-charge model of the battery according to historical charge and discharge data of the battery; sensing current charge and discharge data of the battery; and estimating the first state of charge using the state-of-charge model based on the current charge and discharge data; wherein the state-of-charge model is a charge and discharge curve fitted using the historical charge and discharge data or a look-up table formed using the historical charge and discharge data; the historical charge and discharge data and the current charge and discharge data include the current and / or voltage of the battery; estimating a second state of charge of the battery using a second state-of-charge estimation method; determining a first weight corresponding to the first state of charge and a second weight corresponding to the second state of charge according to the state data of the battery; specifically including: determining the current state of the battery according to the historical charge and discharge data and the current charge and discharge data; and determining the first weight and the second weight according to the current state; wherein determining the current state of the battery specifically includes: determining whether the battery enters a hysteresis state; and when it is determined that the battery enters the hysteresis state, determining the time when the battery is in the hysteresis state; wherein when it is determined that the battery enters the hysteresis state, reducing the first weight and / or increasing the second weight, and gradually adjusting the first weight and / or the second weight according to the time when the battery is in the hysteresis state; and calculating the state of charge of the battery based on the first state of charge and the first weight and the second state of charge and the second weight.

2. The calculation method according to claim 1, wherein the first state-of-charge estimation method is the open-circuit voltage method, and the second state-of-charge estimation method is the ampere-hour integration method.

3. The calculation method according to claim 1, wherein the first state-of-charge estimation method is a method based on a battery equivalent circuit model based on at least one of an R-int equivalent circuit model, a first-order RC equivalent circuit model, and a second-order RC equivalent circuit model of the battery.

4. The calculation method according to claim 1, wherein the battery is a lithium-ion battery or a sodium-ion battery.

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