A method to improve battery SOC detection accuracy

Abstract

A method for improving battery SOC detection accuracy includes the following steps: Step 1: Calculating the battery's state, including a fully charged state, a fully discharged state, and an intermediate state; Step 2: Calculating the SOC value based on the battery's state; and Step 3: Performing a weighted calculation on the SOC value based on the rest time. Based on experiments, the present invention divides the battery's charge and discharge process into a fully charged state, an intermediate state, and a fully discharged state. Open-circuit voltage correction is performed by consulting different OCV tables based on the battery's charge and discharge state to improve correction accuracy. Furthermore, a method of current integration and weighted calculation of the open-circuit voltage correction value is employed to improve the real-time nature of the correction.

Description

Technical Field

[0001] The present invention relates to the technical field of battery capacity measurement, and in particular to a method for improving battery SOC detection accuracy. Background Art

[0002] With the development of intelligent automobiles, the application of automobile battery management functions is becoming more and more extensive. The remaining capacity of the battery, namely SOC, is

[0003] This is the core function of the battery management system, and also the difficulty and key point. The battery's SOC cannot be measured directly and can only be estimated by measuring current, voltage, and temperature. This requires consideration of the battery's operating environment, charge and discharge rates, aging, battery type, and measurement errors.

[0004] The basic algorithm for SOC estimation is ampere-hour integration, with open-circuit voltage correction applied when certain conditions are met. Experiments have shown that batteries exhibit hysteresis, where the charge and discharge state before rest affects the open-circuit voltage, leading to deviations in the SOC value corresponding to OCV. Traditional open-circuit voltage correction requires stringent activation conditions, requiring the battery to rest for four hours after a charge or discharge cycle. At this point, the open-circuit voltage conforms to the OCV table. However, under certain operating conditions, correction may not be possible within a single charge and discharge cycle, leading to increasing cumulative errors when relying solely on ampere-hour integration. Summary of the Invention

[0005] In order to solve the above problems, a method for improving the detection accuracy of battery SOC is provided.

[0006] The object of the present invention is achieved in the following manner:

[0007] A method for improving battery SOC detection accuracy, the method comprising the following steps:

[0008] Step 1: Calculate the state of the battery, which includes fully charged state, fully discharged state, and intermediate state:

[0009] Step 2: Calculate the SOC value according to the battery status;

[0010] Step 3: Perform weighted calculation on the SOC value based on the stationary time.

[0011] The step 1 specifically includes: using the formula Calculate, where alpha is the hysteresis factor, ranging from [-10000, +10000], Current is the charge and discharge current, in A, and 1S is the current detection period;

[0012] BAT_AH is the battery capacity, i.e., in hours;

[0013] When alpha ≤ -10000, it means the battery is in a fully charged state;

[0014] When alpha ≥ 10000, it means the battery is in a fully discharged state;

[0015] When -10000 < alpha < 10000, it represents an intermediate state.

[0016] The specific steps of step two include: before standing still, the battery state is fully discharged. Check the discharge OCV table, and SOC = SOCdischarg;

[0017] When the battery is in a fully charged state, check the charge OCV table, and SOC = SOCcharg;

[0018] When the battery is in an intermediate state, check the charge OCV table and the discharge OCV table respectively, and then calculate by weighting. The formula for the intermediate state is as follows:

[0019]

[0020] Where SOCdischarg is the discharge OCV table and SOCcharg is the charge OCV table.

[0021] The specific steps of step three include: when the standing still time is greater than 120 minutes, the SOC value completely depends on the value checked from the OCV table; when the standing still time is less than 1 minute, the SOC value completely depends on the current integral value; when the standing still time T is between 1 minute and 120 minutes, take the weighted calculated value of the value checked from the table and the current integral value. The formula is as follows: [[ID=2,6]]

[0022] Integral,

[0023] Where T is the standing still time and SOC integral is the integral value of the current over time.

[0024] The beneficial effects of the present invention: Through the SOC correction algorithm and the SOC weighting algorithm with hysteresis effect, the present invention can perform OCV correction when the standing still time does not reach the requirement of the battery standing still time, eliminate the error of the ampere-hour integration of the battery during operation, and improve the accuracy of the battery SOC. Description of the Drawings

[0025] Figure 1 It is the flowchart of the hysteresis effect correction algorithm of the present invention.

[0026] Figure 2 It is the flowchart of the weighting algorithm of the present invention. Detailed Embodiments

[0027] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0028] It should be noted that the following detailed description is exemplary and aims to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same technical meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] The present invention provides a method for improving the detection accuracy of the SOC of a storage battery. The present invention needs to obtain the SOC-OCV table in the fully charged state, overstate, and fully discharged state through tests. The method includes the following steps:

[0031] Step 1: Calculate the state of the storage battery, and the state includes the fully charged state, the fully discharged state, and the intermediate state:

[0032] Step 2: Calculate the SOC value according to the state of the storage battery;

[0033] Step 3: Perform weighted calculation on the SOC value according to the stationary time.

[0034] The specific content of Step 1 includes: using formula ① for calculation, where alpha is the hysteresis factor, with a range of [-10000, +10000], Current is the charge and discharge current, with the unit A, 1S is the current detection period; BAT_AH is the capacity of the storage battery, that is, in ampere-hours;

[0035] If alpha ≤ -10000, it represents that the storage battery is in the fully charged state;

[0036] If alpha ≥ 10000, it represents that the storage battery is in the fully discharged state;

[0037] If -10000 < alpha < 10000, it represents the intermediate state.

[0038] The specific content of Step 2 includes: when the state of the storage battery before stationary is the fully discharged state, check the discharge OCV table, and SOC = SOCdischarg;

[0039] When the storage battery is in the fully charged state, check the charge OCV table, and SOC = SOCcharg;

[0040] When the battery is in the intermediate state, check the charging OCV table and the discharging OCV table respectively, and then perform weighted calculation. The intermediate state formula ② is as follows:

[0041]

[0042] SOCdischarg is the discharge OCV table, and SOCcharg is the charge OCV table. (The discharge OCV table is a table where each SOC of the battery corresponds to a voltage, so it is a table of the correspondence between SOC and voltage.)

[0043] The step 3 specifically includes: when the stationary time is greater than 120 minutes, the SOC value is completely determined by the value in the OCV table; when the stationary time is less than 1 minute, the SOC value is completely determined by the current integral value; when the stationary time T is between 1 minute and 120 minutes, a weighted calculation value is obtained by taking the table value and the current integral value, and formula ③ is as follows:

[0044] integral,

[0045] Where T is the stationary time, and SOC integral is the integral value of current over time.

[0046] The present invention is based on experiments and divides the battery charging and discharging process into a fully charged state, an intermediate state, and a fully discharged state. The open circuit voltage correction is performed by looking up different OCV tables according to the battery's charging and discharging state to improve the accuracy of the correction. At the same time, a method of current integration and weighted calculation of the open circuit voltage correction value is adopted to improve the real-time performance of the correction.

[0047] The present invention uses the SOC correction algorithm of the hysteresis effect and the SOC weighting algorithm to perform OCV (open circuit voltage) correction when the rest time does not meet the battery rest time requirement, eliminate the error of the battery ampere-hour integration during operation, and improve the battery SOC accuracy.

[0048] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

[0049] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A method for improving battery SOC detection accuracy, characterized by: The method comprises the following steps: Step 1: Calculate the state of the battery, which includes fully charged state, fully discharged state, and intermediate state: Step 2: Calculate the SOC value according to the battery status; The second step specifically includes: before the battery stops, the battery is in a fully discharged state, and the discharge OCV table is checked. SOC=SOCdischarg; When the battery is fully charged, check the charging OCV table, SOC = SOCcharg; When the battery is in the intermediate state, check the charging OCV table and the discharging OCV table respectively, and then perform weighted calculation. The intermediate state formula is as follows: Among them, SOCdischarg is the discharge OCV table, and SOCcharg is the charge OCV table; Step 3: Perform weighted calculation on the SOC value based on the stationary time.

2. The method for improving battery SOC detection accuracy according to claim 1, characterized in that: The step 1 specifically includes: using the formula Calculate, where alpha is the hysteresis factor, ranging from [-10000, +10000], Current is the charge and discharge current, in A, and 1S is the current detection period; BAT_AH is the battery capacity, i.e., in hours; If alpha ≤ -10000, it means the battery is fully charged; If alpha ≥ 10000, it means the battery is fully discharged; If -10000 <alpha Values ​​<10000 represent intermediate states.

3. The method for improving battery SOC detection accuracy according to claim 1, characterized in that: The step three specifically includes: when the stationary time is greater than 120 minutes, the SOC value is completely determined by the value in the OCV table; when the stationary time is less than 1 minute, the SOC value is completely determined by the current integral value; when the stationary time T is between 1 minute and 120 minutes, a weighted calculation value is obtained by taking the table value and the current integral value, and the formula is as follows: Where T is the stationary time, and SOC integral is the integral value of current over time.

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