A battery soc estimation method, estimation system, and power battery system

Abstract

The application relates to the field of batteries, in particular to a battery SOC estimation method, an estimation system and a power battery system. The battery SOC estimation method comprises the following steps: A, obtaining a display SOC value by using an ampere-hour integration method; B, detecting a dynamic voltage of a battery charging system, and obtaining a corrected SOC value in a dynamic voltage / SOC matrix table according to the dynamic voltage; and C, comparing the display SOC value with the corrected SOC value, and determining a display mode of the display SOC value according to a comparison result. Compared with the prior art, the battery SOC estimation method provided by the application can obtain a corrected SOC value in a dynamic voltage / SOC table according to a dynamic voltage of a battery system during charging, compare the corrected SOC value with a display SOC value obtained by using an ampere-hour integration method, determine a final display SOC value according to a comparison result, and thus can ensure that the residual capacity of the battery can be accurately fed back before the vehicle starts discharging after being charged, which is a great progress in the field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery, in particular to a battery SOC estimation method, estimation system and power battery system. BACKGROUND

[0002] At present, the environment of human society is seriously damaged, and fossil energy is increasingly exhausted. In order to improve the current situation, various countries have begun to limit the manufacture and use of fuel vehicles and vigorously develop new energy vehicles.

[0003] In new energy vehicles, the main direction is pure electric vehicles. As a key component of pure electric new energy vehicles, the design of power batteries is particularly important. The SOC estimation of battery system has always been a focus. Unlike gasoline in fuel vehicles, which can intuitively understand the remaining oil quantity and remind users to reasonably use and add fuel to the vehicle, the capacity of lithium batteries can only be indirectly obtained by comparing the voltage and the total capacity of the battery recorded in the test. It is indirectly calculated.

[0004] The commonly used estimation method is ampere-hour integration method. If the current measurement is not accurate in the application of ampere-hour integration method, the SOC calculation error will be caused, and the error will become larger and larger with long-term accumulation; the battery charge and discharge efficiency needs to be considered; in the case of high temperature and severe current fluctuation, the error is larger; this method has become an important link in battery management in the estimation of SOC, but the battery capacity will also be affected by aging and temperature changes, so it is difficult to accurately obtain the remaining capacity of the battery system. However, if the user cannot accurately obtain the power information, the user is easy to make a wrong judgment on the vehicle condition, which may cause the vehicle to be stranded on the road due to lack of power.

[0005] The patent document with application number 201810664200.5 discloses a SOC estimation algorithm for a battery. The purpose is to prevent the SOC value of the battery from jumping in the case of static equipment, and does not disclose how to ensure that the displayed SOC value is the actual SOC value during charging.

[0006] Therefore, the prior art still has deficiencies, and the inventors need to develop it. SUMMARY

[0007] In view of the deficiencies of the prior art described above, the purpose of the present application is to provide a battery SOC estimation method, system and device, which can improve the SOC estimation accuracy during charging, so as to accurately feedback the remaining battery capacity before the vehicle starts discharging after charging.

[0008] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0009] A battery SOC estimation method, comprising steps of:

[0010] A, obtaining a display SOC value by ampere-hour integration method;

[0011] B, detecting a dynamic voltage of a battery charging system, and obtaining a corrected SOC value according to the dynamic voltage in a dynamic voltage / SOC matrix table;

[0012] C, comparing the display SOC value with the corrected SOC value, and determining a display mode of the display SOC value according to a comparison result.

[0013] Preferably, the battery SOC estimation method further comprises:

[0014] B1, detecting a SOH value and a temperature value of a current battery, and obtaining a matching DCR value of the battery according to a DCR / SOH matrix table;

[0015] B2, detecting a current charging current, and reading an initial DCR value of the battery;

[0016] B3, calculating a corrected voltage value according to the dynamic voltage, the current charging current, the matching DCR value and the initial DCR value;

[0017] B4, obtaining the corrected SOC value according to the corrected voltage value in the dynamic voltage / SOC matrix table.

[0018] Preferably, the battery SOC estimation method further comprises:

[0019] Preferably, the battery SOC estimation method further comprises:

[0020] C1, determining whether a difference between the display SOC value and the corrected SOC value is greater than a first predetermined value, if yes, executing a corrected display SOC value, and if no, executing step C2;

[0021] C2, determining whether the display SOC value is 100%, if yes, ending charging, and if no, executing step A.

[0022] Preferably, the battery SOC estimation method further comprises:

[0023] C11, determining whether the display SOC value is greater than the corrected SOC value, if yes, executing step C12, and if no, executing step C14;

[0024] C12, stopping increasing the display SOC value;

[0025] C13, whether the display SOC value is equal to the corrected SOC value, if yes, executing step C2, if no, executing step B;

[0026] C14, increasing the coefficient of ampere-hour integration by a second predetermined value, to increase the increasing rate of the display SOC value;

[0027] C15, whether the display SOC value is equal to the corrected SOC value, if yes, executing step C2; if no, executing step C14.

[0028] Preferably, the battery SOC estimation method, the dynamic voltage / SOC matrix table is a dynamic voltage value table recorded from 0% to 100% of SOC value by using the same battery cell to perform full process charging according to the current standard of the battery cell's drop charging standard table;

[0029] The dynamic voltage / SOC matrix table curve is a curve formed according to the dynamic voltage / SOC matrix table.

[0030] Preferably, the battery SOC estimation method, the drop charging standard table is a standard current value matrix table charged at different temperatures and different voltages, which is divided into a fast charging standard table and a slow charging standard table.

[0031] An SOC estimation system applying the method, comprising:

[0032] A storage module for storing the dynamic voltage / SOC matrix table, the drop charging standard table, and the DCR / SOH matrix table;

[0033] A detection module for detecting the dynamic voltage of the charging system and the current charging current;

[0034] A comparison module for obtaining a corrected SOC value in the dynamic voltage / SOC matrix table according to the dynamic voltage value, and comparing the display SOC value with the corrected SOC value.

[0035] Preferably, the SOC estimation system, the comparison module is further used for calculating a corrected voltage value according to the dynamic voltage, the current charging current, the matched DCR value and the initial DCR value, and obtaining the corrected SOC value in the dynamic voltage / SOC table according to the corrected voltage value.

[0036] A power battery system comprising the SOC estimation system.

[0037] Compared with the prior art, the battery SOC estimation method provided by the application can obtain a corrected SOC value in a dynamic voltage / SOC table according to the dynamic voltage of the battery system during charging, compare the corrected SOC value with a display SOC value obtained by using the ampere-hour integral method, and determine a final display SOC value according to the comparison result, so that the remaining battery capacity can be accurately fed back before the vehicle starts discharging after charging, which is a great progress in the field. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a flowchart of the battery SOC estimation method provided by the application;

[0039] Figure 2 is a structural block diagram of the SOC estimation system provided by the application;

[0040] Figure 3 is a fast-charging dynamic voltage / SOC matrix table provided by the application;

[0041] Figure 4 is a slow-charging dynamic voltage / SOC matrix table provided by the application;

[0042] Figure 5 is a curve diagram of the fast-charging dynamic voltage / SOC matrix table provided by the application;

[0043] Figure 6 is a curve diagram of the slow-charging dynamic voltage / SOC matrix table provided by the application;

[0044] Figure 7 is a flowchart of an embodiment of the estimation method provided by the application.

[0045] SOC (State of Charge, battery state of charge)

[0046] SOH (State Of Health, battery capacity, health, performance state)

[0047] DCR (DC Resistance, DC resistance) DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions and effects of the application clearer and more explicit, the application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and do not limit the application.

[0049] Embodiment 1

[0050] Please refer to Figures 1-7 The application provides a battery SOC estimation method, which comprises the following steps:

[0051] S100, obtaining a display SOC value by using an ampere-hour integration method; the ampere-hour integration method is a traditional SOC estimation algorithm of a battery;

[0052] S200, detecting a dynamic voltage of a battery charging system, and obtaining a corrected SOC value according to the dynamic voltage in a dynamic voltage / SOC matrix table;

[0053] S300, comparing the display SOC value with the corrected SOC value, and determining a display mode of the display SOC value according to a comparison result.

[0054] In actual operation, the battery charging system first charges according to a matching instantaneous charging current of a drop current charging standard table during the charging process. The drop current charging standard is a charging standard table under different temperatures and different system voltages, and is divided into two state standard tables of fast charging and slow charging. The fast charging standard table is shown as follows:

[0055]

[0056] The slow charging standard table is shown as follows:

[0057]

[0058] The dynamic voltage / SOC matrix table is established by charging the same battery cell according to the drop current charging standard table, and recording the corresponding relationship between the dynamic voltage and the SOC value under different temperatures, respectively. As shown in Figure 3 、 Figure 4 , and a dynamic voltage / SOC value matrix curve is established according to the corresponding data, as shown in Figure 5 、 Figure 6 .

[0059] In the implementation process, the battery system charges first, and the ampere-hour integration method is used to calculate the electric quantity. The calculated SOC value is directly reported to the whole vehicle as the display SOC value. The dynamic voltage detected is used to assist in real-time SOC correction in cooperation with the dynamic voltage / SOC matrix table to obtain the corrected SOC value, which is saved in the BMS. The calculated SOC value is compared with the corrected SOC value, and a corresponding display mode is selected.

[0060] As a preferred solution, the step S200 specifically includes:

[0061] S210, detecting a SOH value and a temperature value of a current battery, and obtaining a matching DCR value of the battery in cooperation with a DCR / SOH matrix table;

[0062] S220, detecting a current charging current, and reading an initial DCR value of the battery;

[0063] S230, calculating a corrected voltage value according to the dynamic voltage, the current charging current, the matching DCR value and the initial DCR value;

[0064] S240, obtaining the corrected SOC value in the dynamic voltage / SOC matrix table according to the corrected voltage value.

[0065] In a specific implementation, the battery may be caused to deviate from the dynamic voltage due to an increase in internal resistance caused by aging and the like, and before the corrected SOC value is obtained, the same battery cell needs to be cycled throughout the life cycle, and the direct current internal resistance DCR of the battery cell at different temperatures and different SOHs is recorded respectively to obtain the DCR / SOH matrix table (unit: mΩ). Since the DCR of different types of battery cells is different, the DCR / SOH matrix table (unit: mΩ) is as shown in the following table:

[0066] T / S OH t1 t2 t3 t4 …… tm h1 DCR1 1 DCR2 1 DCR3 1 DCR4 1 …… DCRm 1 h2 DCR1 2 DCR2 2 DCR3 2 DCR4 2 …… DCRm 2 h3 DCR1 3 DCR2 3 DCR3 3 DCR4 3 …… DCRm 3 h4 DCR1 4 DCR2 4 DCR3 4 DCR4 4 …… DCRm 4 …… …… …… …… …… …… …… hn DCR1 n DCR2 n DCR3 n DCR4 n …… DCRm n

[0067] Specifically, the DCR values at different SOHs and different temperatures are recorded, and there is a DCR recording point every 2% between 84% and 100%, and a DCR recording point every 1% between 80% and 84%, as shown in the following table (unit: mΩ):

[0068]

[0069] Specifically, the SOH value and the current temperature value of the battery in the current system are read, and the matching DCR value and the initial DCR value of the battery at this time are obtained in cooperation with the DCR / SOH matrix table, which are denoted as DCR X and DCR 初始 , respectively. The DCR 初始 is the DCR internal resistance value when the SOH of the battery is 100%.

[0070] Meanwhile, the current charging current is detected, and the initial DCR value of the battery is read; a corrected voltage value is calculated according to the dynamic voltage, the current charging current, the matching DCR value and the initial DCR value; and the corrected voltage value calculation formula is:

[0071] U 修正 = U 动态 -(I 充 *DCR X -I 充 *DCR 初始 ,

[0072] wherein U 修正 is the corrected voltage value, U 动态 is the detected dynamic voltage, I 充for the detected current charging current; DCR X for the matched DCR value, DCR 初始 for the initial DCR value.

[0073] The modified SOC value is obtained by using the modified voltage value and the dynamic voltage / SOC matrix table.

[0074] As a preferred solution, the modified SOC value is matched on the dynamic voltage / SOC value matrix curve.

[0075] As a preferred solution, the step S300 comprises:

[0076] S310, whether the difference between the display SOC value and the modified SOC value is greater than a first predetermined value, if yes, then execute the modified display SOC value, if no, then execute step S320;

[0077] S320, whether the display SOC value is 100%, if yes, then end the charging, if no, then execute step S100.

[0078] The specific modified display SOC value specifically comprises the steps of:

[0079] S311, whether the display SOC value is greater than the modified SOC value, if yes, then execute step S312, if no, then execute step S314;

[0080] S312, stop the numerical value increase of the display SOC value;

[0081] S313, whether the display SOC value is equal to the modified SOC value, if yes, then execute step S320, if no, then execute step S200;

[0082] S314, increase the coefficient of the ampere-hour integral method by a second predetermined value, to increase the increase rate of the display SOC value;

[0083] S315, whether the display SOC value is equal to the modified SOC value, if yes, then execute step S320, if no, then execute step S314.

[0084] Specifically, when the difference between the display SOC value and the modified SOC value exceeds the first predetermined value, which can be set to 1%, the modified display SOC step is started.

[0085] Specifically, if the display SOC value is too large, for example, greater than the corrected SOC value by 2%, the display SOC value is stopped from increasing, and when the corrected SOC value is equal to the display SOC value, the display SOC value is accumulated by the ampere-hour integration method; if the display SOC value is too small, for example, less than the corrected SOC value by 2%, the coefficient of the ampere-hour integration method is increased by a second predetermined value, for example, the coefficient of the ampere-hour integration method is multiplied by 2 to accelerate the accumulation speed of the display SOC value, and when the display SOC value is equal to the corrected SOC value, the coefficient of the ampere-hour integration method is adjusted back to the normal 1 times coefficient.

[0086] Embodiment 2

[0087] Please refer to Figure 2 The SOC estimation system provided by the application comprises:

[0088] The storage module is used for storing the dynamic voltage / SOC matrix table, the current reduction charging standard table, and the DCR / SOH matrix table.

[0089] The detection module is used for detecting the dynamic voltage of the charging system and the current charging current.

[0090] The comparison module is used for obtaining a corrected SOC value according to the dynamic voltage value in the dynamic voltage / SOC matrix table, and comparing the display SOC value with the corrected SOC value.

[0091] As a preferred solution, the comparison module is further used for calculating a corrected voltage value according to the dynamic voltage, the current charging current, the matched DCR value, and the initial DCR value, and obtaining the corrected SOC value according to the matched corrected voltage value in the dynamic voltage / SOC table.

[0092] Embodiment 3

[0093] The application further provides a power battery system comprising the estimation system of embodiment 2.

[0094] In the implementation process, the following is specifically implemented:

[0095] In actual application, when preparing to charge, the battery system charges according to the current standard of the current reduction charging standard table, first uses the ampere-hour integration method to calculate the power of the battery, the calculated SOC is directly reported to the vehicle instrument panel as the SOC display, then reads the current SOH value and temperature value of the battery system through the BMS, collects the dynamic voltage U 动态 of the current state, searches the DCR / SOH matrix table to obtain the DCR internal resistance value at this time, and defines the DCR internal resistance value as DCR X , and calculates the current reduction charging standard table according to the formula U 修正 = U 动态 -(I充 DCR X I 充 DCR 初始 ), the dynamic voltage is corrected, the corrected dynamic voltage is obtained, the corrected dynamic voltage is used to obtain the corrected SOC value according to the dynamic voltage / SOC matrix table, when the difference between the calculated SOC value and the corrected SOC value exceeds 1%, the corrected display SOC value is started to be displayed; if the calculated SOC value is greater than the corrected SOC value, the increase of the calculated SOC value is stopped until the calculated SOC value = the corrected SOC value, and the SOC accumulation calculation by the ampere-hour integration method is continued; if the calculated SOC display is less than the corrected SOC value, the coefficient of the ampere-hour integration method is multiplied by 2 to accelerate the accumulation speed of the calculated SOC value, when the SOC display = the real SOC, the coefficient of the ampere-hour integration method is adjusted back to the normal 1 times coefficient, the corrected display SOC is completed, the accuracy of the SOC display value is ensured, and accurate power reminding is given to the user.

[0096] It can be understood that, for those skilled in the art, equivalent replacements or changes can be made according to the technical solutions and the inventive concept of the present application, and all these changes or replacements shall belong to the protection scope of the claims attached to the present application.

Claims

1. A battery SOC estimation method characterized by, The method comprises the steps of: A. obtaining a display SOC value by using ampere-hour integration method; B. detecting a dynamic voltage of a battery charging system, and obtaining a corrected SOC value in a dynamic voltage / SOC matrix table, wherein the dynamic voltage / SOC matrix table is a dynamic voltage and SOC mapping table obtained by a same battery cell under a current reduction charging standard table experiment, a dynamic voltage value table from 0% to 100% of the SOC value is recorded, and the current reduction charging standard table is a standard current value matrix table under different temperatures and different voltages, which is divided into a fast charging standard table and a slow charging standard table; C. comparing the display SOC value with the corrected SOC value, and determining a display mode of the display SOC value according to a comparison result; The step B further comprises: B1. detecting a SOH value and a temperature value of a current battery, and obtaining a matching DCR value of the battery by using a DCR / SOH matrix table, wherein the DCR / SOH matrix table is a DCR of the battery cell under different temperatures and different SOHs in a full life cycle; B2. detecting a current charging current, and reading an initial DCR value of the battery, wherein the initial DCR value is a DCR value when the SOH of the battery is 100%; B3. calculating a corrected voltage value according to the dynamic voltage, the current charging current, the matching DCR value and the initial DCR value, wherein the corrected voltage value calculation formula is: U 修正 = U 动态 - (I 充 * DCR X - I 充 * DCR 初始 ) ， wherein, U 修正 is the correction voltage value, U 动态 is the detected dynamic voltage, I 充 is the detected current charging current; DCR X is the matching DCR value, DCR 初始 is the initial DCR value; B4. obtaining the corrected SOC value in the dynamic voltage / SOC matrix table according to the corrected voltage value.

2. The battery SOC estimation method according to claim 1, characterized by, The step C comprises: C1. whether a difference between the display SOC value and the corrected SOC value is greater than a first predetermined value, if yes, executing a corrected display SOC value, and if no, executing a step C2; C2. whether the display SOC value is 100%, if yes, ending charging, and if no, executing the step A.

3. The battery SOC estimation method according to claim 2, characterized by, The corrected display SOC value comprises the steps of: C11. whether the display SOC value is greater than the corrected SOC value, if yes, executing a step C12, and if no, executing a step C14; C12. stopping a value increase of the display SOC value; C13. whether the display SOC value is equal to the corrected SOC value, if yes, executing the step C2, and if no, executing the step B; C14. increasing a coefficient of the ampere-hour integration method by a second predetermined value, and increasing an increase rate of the display SOC value; C15. whether the display SOC value is equal to the corrected SOC value, if yes, executing the step C2, and if no, executing the step C14.

4. The battery SOC estimation method according to claim 1, characterized by, The method further comprises forming a dynamic voltage / SOC matrix table curve according to the dynamic voltage / SOC matrix table, and the dynamic voltage / SOC matrix table curve is used for matching the corrected SOC value.

5. A SOC estimation system applying the method according to any one of claims 1 to 4, characterized by The method comprises: a storage module for storing the dynamic voltage / SOC matrix table, the current reduction charging standard table and the DCR / SOH matrix table; a detection module for detecting a dynamic voltage of a charging system and a current charging current; The comparison module is configured to obtain a corrected SOC value from a dynamic voltage / SOC table according to the dynamic voltage value; and compare the display SOC value with the corrected SOC value.

6. The SOC estimation system according to claim 5, characterized by, The comparison module is further configured to calculate a corrected voltage value according to the dynamic voltage value, the current charging current, the matched DCR value and the initial DCR value; and obtain the corrected SOC value from the dynamic voltage / SOC table according to the corrected voltage value.

7. A power battery system, characterized in that, The SOC estimation system of claim 5 is included.

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