A battery status online evaluation method and system

Abstract

The present invention provides a method for online evaluation of battery status. The present invention realizes online evaluation of the battery system status by monitoring the voltage of each single cell in the battery system, accurately predicts the location of the faulty single cell in the battery system, and determines the type of battery fault, whether it is a problem with the external connection of the battery or a problem with the battery itself, thereby assisting maintenance personnel in making decisions; if it is an external connection problem, there is no need to replace the battery, only the battery connection needs to be reinforced or repaired, which can greatly reduce maintenance time and maintenance costs; if it is a battery single cell fault, the faulty battery can be directly replaced, thereby reducing maintenance time.

Description

Technical Field

[0001] The invention relates to the field of battery detection calculation, and in particular to a battery status online evaluation method and system. Background Art

[0002] Battery safety has always been the most concerned issue for users. The reliability of the battery itself is important, but the battery system's ability to predict battery safety in advance is also indispensable. There are many signs of battery failure in the early stages, such as increased internal resistance, reduced capacity, and increased ambient temperature. However, in most cases, the initial reaction to battery failure is a decrease in voltage.

[0003] Patent application number CN201810278942.4 discloses a method for diagnosing battery faults in a battery pack, which can achieve reliable diagnosis of power battery pack faults, reduce misjudgment of battery pack faults, avoid unnecessary repeated maintenance of battery packs, and save maintenance costs. The battery pack is diagnosed as a whole through the highest voltage value Vmax and the lowest voltage value Vmin of the battery pack series module, which is beneficial to improving the diagnostic efficiency of the battery pack and screening faulty battery packs for accurate diagnosis. In addition, the present invention is beneficial to ensure that the fault detection of the battery pack conforms to the actual application environment through the operation of the whole vehicle, and through remote monitoring data, it is beneficial to provide a reference basis for parameter setting in fault detection.

[0004] However, the above method still has many shortcomings: 1) Faulty batteries can only be screened out after the battery has been left stationary for several hours, while battery failures mostly occur when the battery is running, which makes it difficult to leave it stationary; 2) The overall diagnosis of the battery pack through the maximum voltage value Vmax and the minimum voltage value Vmin is not accurate enough. Due to the differences in the production of battery cells and the external circuits and detection circuits after the batteries are grouped, there is an inherent consistency problem, that is, there is a certain difference between the maximum voltage value Vmax and the minimum voltage value Vmin in the initial state, and there is a situation where the internal cell is damaged but the difference between the maximum voltage value Vmax and the minimum voltage value Vmin is still within the permitted range; 3) The position of the faulty battery cannot be accurately located by the difference between the maximum voltage value Vmax and the minimum voltage value Vmin; 4) The fault type of the faulty battery cannot be accurately located by the difference between the maximum voltage value Vmax and the minimum voltage value Vmin, whether it needs to be replaced or repaired. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a device capable of monitoring the voltage of each single battery in a battery system and realizing online evaluation of the battery system status.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A method for online evaluation of battery status comprises the following steps:

[0008] Step 1: Count the voltage information of each battery string in a battery system in good health to form a standard voltage curve A, and set a battery voltage change safety threshold β;

[0009] Step 2, obtaining a voltage distribution curve a of the battery system to be tested at the end of discharge;

[0010] Step 3, comparing curve a with the curve A, that is, curve A-curve a to obtain a comparison curve B consisting of ΔV1, ΔV2, ΔV3---ΔVn; wherein n represents the nth string of batteries in the battery system to be tested;

[0011] Step 4, calculating the voltage fluctuation value b of the nth battery string = ΔVn-ΔVave;

[0012] Step 5: If ±b<β, it is determined to be safe, otherwise the nth battery string is determined to be faulty;

[0013] Step 6: If the nth string of batteries is found to be faulty, compare the voltage fluctuation values ​​b collected several times before and after the nth string of batteries. If b shows an increasing or decreasing trend, the nth string of batteries is determined to be poorly soldered and the welding strength of the nth string of batteries needs to be increased; otherwise, the nth string of batteries is determined to be damaged and needs to be replaced.

[0014] The present invention monitors the voltage of each cell in the battery system to achieve online evaluation of the battery system status, accurately predict the location of the faulty cell in the battery system, and determine the type of battery failure, whether it is a problem with the battery's external connection or the battery itself, thereby assisting maintenance personnel in making decisions; if it is an external connection problem, there is no need to replace the battery, only the battery connection needs to be reinforced or repaired, which can greatly reduce maintenance time and maintenance costs; if it is a battery cell failure, the faulty battery can be directly replaced, thereby reducing maintenance time.

[0015] Furthermore, the step 1 is specifically as follows:

[0016] Step 11, select a battery system in good health, and arrange voltage sampling lines at both ends of each battery string 1, 2, 3-n in the battery system to collect potential signals at both ends of the battery;

[0017] Step 12, discharge the battery system in good health, and record the potentials vn+1 and vn on both sides of each battery string at the characteristic time point at the end of the discharge, and collect data once every set time period;

[0018] Step 13, calculate the voltage of each battery string: Vn=vn+1-vn, forming a standard voltage curve A of each battery string in the battery system at the end of discharge;

[0019] Step 14: Set the battery voltage change safety threshold β.

[0020] Furthermore, the step 1 specifically includes: entering the standard voltage curve A and the battery voltage change safety threshold β into the battery management system BMS.

[0021] Furthermore, the battery system to be tested is connected to a battery management system BMS via a voltage sampling line.

[0022] Corresponding to the above method, the present invention also provides a battery status online evaluation system, comprising the following steps:

[0023] The comparison data building module is used to collect the voltage information of each battery string in a battery system in good health, form a standard voltage curve A, and set a battery voltage change safety threshold β;

[0024] The data acquisition module of the battery system to be tested is used to obtain the voltage distribution curve a of the battery system to be tested at the end of discharge;

[0025] A comparison module is used to compare curve a with the curve A, that is, curve A-curve a to obtain a comparison curve B composed of ΔV1, ΔV2, ΔV3---ΔVn; wherein n represents the nth string of batteries in the battery system to be tested;

[0026] A calculation module, used to calculate the voltage fluctuation value b=ΔVn-ΔVave of the nth battery string;

[0027] The judgment module determines that if ±b<β, it is safe, otherwise it is determined that the nth string of batteries is faulty; if the nth string of batteries is found to be faulty, the voltage fluctuation values ​​b collected several times before and after the nth string of batteries are compared, and if b shows an increasing or decreasing trend, it is determined that the nth string of batteries is poorly soldered, and the welding strength of the nth string of batteries needs to be increased; otherwise, it is determined that the nth string of batteries is damaged and needs to be replaced.

[0028] Furthermore, the specific execution process of the comparison data construction module is as follows:

[0029] Step 11, select a battery system in good health, and arrange voltage sampling lines at both ends of each battery string 1, 2, 3-n in the battery system to collect potential signals at both ends of the battery;

[0030] Step 12, discharge the battery system in good health, and record the potentials vn+1 and vn on both sides of each battery string at the characteristic time point at the end of the discharge, and collect data every set time;

[0031] Step 13, calculate the voltage of each battery string: Vn=vn+1-vn, forming a standard voltage curve A of each battery string in the battery system at the end of discharge;

[0032] Step 14: Set the battery voltage change safety threshold β.

[0033] Furthermore, in the comparison data construction module, the standard voltage curve A and the battery voltage change safety threshold β are entered into the battery management system BMS.

[0034] Furthermore, the battery system to be tested is connected to a battery management system BMS via a voltage sampling line.

[0035] The advantages of the present invention are:

[0036] 1) Realize online evaluation of battery system faults. The status of each battery string can be evaluated while the battery system is charging or discharging, without the need to leave it idle or power off. This improves the online evaluation capability of the battery system and the ability to predict faulty batteries.

[0037] 2) The status of each battery string in the battery system can be accurately predicted to avoid the battery being affected by internal and external differences such as battery production, battery group external circuit and temperature;

[0038] 3) It can accurately locate the specific location of the faulty battery, helping maintenance personnel to find the faulty battery in time, reducing battery maintenance time and improving battery maintenance efficiency;

[0039] 4) It can determine the specific fault type of the faulty battery, whether it is a problem with the battery's external connection or a battery failure, to avoid wasting useful batteries and unnecessary removal and replacement of batteries by maintenance personnel, thereby reducing maintenance time and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a judgment flow chart of a battery status online evaluation method in an embodiment of the present invention;

[0041] Figure 2 Schematic diagram of a standard voltage curve A of the online battery status evaluation method according to an embodiment of the present invention;

[0042] Figure 3 Schematic diagram of a test battery voltage distribution curve a of the battery status online evaluation method in an embodiment of the present invention;

[0043] Figure 4 Schematic diagram of a voltage fluctuation value b curve of the battery status online evaluation method in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Corresponding to the above method, this embodiment also discloses a battery status online evaluation system, which specifically includes:

[0046] The comparison data building module is used to collect the comparison data, including the following steps:

[0047] S1: Select a battery system in good health, and arrange voltage sampling lines at both ends of each battery string 1, 2, 3-n in the battery system to collect potential signals at both ends of the battery;

[0048] S2: Discharge the battery system and record the potentials vn+1 and vn on both sides of each battery string at a characteristic time point at the end of the discharge, and collect data every few minutes;

[0049] S3: Calculate the voltage of each battery string: Vn = vn + 1 - vn, and form a standard voltage curve A of each battery string in the battery system at the end of discharge, such as Figure 2 As shown, it is used for data comparison;

[0050] S4: Setting the battery voltage change safety threshold β;

[0051] S5: Enter the collected standard voltage curve A and the set battery voltage change safety threshold β into the battery system as a reference;

[0052] The test battery system data acquisition module is used to obtain the voltage distribution curve a of the test battery system at the end of discharge; refer to steps S2-S3 in the comparison data construction module to obtain the voltage distribution curve a of the test battery system at the end of discharge, such as Figure 3 As shown,

[0053] The comparison module is used to compare the curve a with the curve A, that is, the curve A-curve a obtains the comparison curve B composed of ΔV1, ΔV2, ΔV3---ΔVn, such as Figure 4 As shown;

[0054] A calculation module is used to calculate the average value of the comparison curve B ΔVave=(ΔV1+ΔV2+ΔV3+---ΔVn) / n; S5: Calculate the voltage fluctuation value b of battery n=ΔVn-ΔVave;

[0055] The evaluation module determines that if ±b < β, it is safe, otherwise it determines that the nth string of batteries is faulty. If the nth string of batteries is found to be faulty, the voltage fluctuation values ​​b collected several times before and after the nth string of batteries are compared. If b shows an increasing or decreasing trend, it is determined that the nth string of batteries is poorly soldered and the welding strength of the nth string of batteries needs to be increased; otherwise, the nth string of batteries is determined to be damaged and needs to be replaced.

[0056] In this embodiment, the standard voltage curve A is obtained under the test environment where the battery works normally; the standard voltage curve A is stored in the battery management system BMS for data comparison; the battery system to be tested is connected to the BMS through a voltage sampling line, and the BMS processes, analyzes and judges the voltage data potential signal.

[0057] By monitoring the voltage of each cell in the battery system, the online evaluation of the battery system status can be achieved, and the location of the faulty cell in the battery system can be accurately predicted. The type of battery failure can be determined, whether it is a problem with the external connection of the battery or a problem with the battery itself, thereby assisting maintenance personnel in making decisions; if it is an external connection problem, there is no need to replace the battery, only the battery connection needs to be reinforced or re-welded, which can greatly reduce maintenance time and maintenance costs; if it is a battery cell failure, the faulty battery can be directly replaced, thereby reducing maintenance time.

[0058] This embodiment discloses a method for online evaluation of battery status. Figure 1 As shown, the specific steps include:

[0059] Step 1: Collect comparison data

[0060] S1: Select a battery system in good health, and arrange voltage sampling lines at both ends of each battery string 1, 2, 3-n in the battery system to collect potential signals at both ends of the battery;

[0061] S2: Discharge the battery system and record the potentials vn+1 and vn on both sides of each battery string at a characteristic time point at the end of the discharge, and collect data every few minutes;

[0062] S3: Calculate the voltage of each battery string: Vn = vn + 1 - vn, and form a standard voltage curve A of each battery string in the battery system at the end of discharge, such as Figure 2 As shown, it is used for data comparison;

[0063] S4: Setting the battery voltage change safety threshold β;

[0064] Step 2: Battery System Status Assessment

[0065] S1: Enter the standard voltage distribution curve collected in step 1 into the battery system as a reference;

[0066] S2: Referring to S2-S3 of step 1, obtain the voltage distribution curve a of the test battery system at the end of discharge, such as Figure 3 As shown;

[0067] S3: Compare the curve a with the curve A, that is, curve A-curve a to obtain a comparison curve B consisting of ΔV1, ΔV2, ΔV3---ΔVn, such as Figure 4 As shown;

[0068] S4: Calculate the average value of comparison curve B ΔVave = (ΔV1 + ΔV2 + ΔV3 + --- ΔVn) / n

[0069] S5: Calculate the voltage fluctuation value b of battery n = ΔVn-ΔVave;

[0070] S6: If ±b<β, it is determined to be safe, otherwise it is determined that the nth string of batteries is faulty. If a fault is found in the nth string of batteries, the voltage fluctuation values ​​b collected several times before and after the nth string of batteries are compared. If b shows an increasing or decreasing trend, it is determined that the nth string of batteries is poorly soldered and the welding strength of the nth string of batteries needs to be increased; otherwise, it is determined that the nth string of batteries is damaged and needs to be replaced.

[0071] In this embodiment, the standard voltage curve A is obtained under the test environment where the battery works normally; the standard voltage curve A is stored in the battery management system BMS for data comparison; the battery system to be tested is connected to the BMS through a voltage sampling line, and the BMS processes, analyzes and judges the voltage data potential signal.

[0072] By monitoring the voltage of each cell in the battery system, the online evaluation of the battery system status can be achieved, and the location of the faulty cell in the battery system can be accurately predicted. The type of battery failure can be determined, whether it is a problem with the external connection of the battery or a problem with the battery itself, thereby assisting maintenance personnel in making decisions; if it is an external connection problem, there is no need to replace the battery, only the battery connection needs to be reinforced or re-welded, which can greatly reduce maintenance time and maintenance costs; if it is a battery cell failure, the faulty battery can be directly replaced, thereby reducing maintenance time.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for online evaluation of battery status, It is characterized in that The following steps are involved: Step 1: Count the voltage information of each battery string in a battery system in good health to form a standard voltage curve A, and set a battery voltage change safety threshold β; Step 2, obtaining a voltage distribution curve a of the battery system to be tested at the end of discharge; Step 3, comparing curve a with the curve A, that is, curve A-curve a to obtain a comparison curve B consisting of ΔV1, ΔV2, ΔV3---ΔVn; wherein n represents the nth string of batteries in the battery system to be tested; Step 4, calculate the average value of the comparison curve B ΔVave = (ΔV1 + ΔV2 + ΔV3 + --- ΔVn) / n, and then calculate the voltage fluctuation value b = ΔVn-ΔVave of the nth string of batteries; Step 5: If ±b<β, it is determined to be safe, otherwise it is determined that the nth battery string is faulty; Step 6: If a fault is found in the nth string of batteries, compare the voltage fluctuation values ​​b collected several times before and after the nth string of batteries. If b shows an increasing or decreasing trend, the nth string of batteries is judged to be poorly soldered and the welding strength of the nth string of batteries needs to be increased; otherwise, the nth string of batteries is judged to be damaged and needs to be replaced.

2. The method for online evaluation of battery status according to claim 1, It is characterized in that The step 1 is specifically as follows: Step 11, select a battery system in good health, and arrange voltage sampling lines at both ends of each battery string 1, 2, 3-n in the battery system to collect potential signals at both ends of the battery; Step 12, discharge the battery system in good health, and record the potentials vn+1 and vn on both sides of each battery string at the characteristic time point at the end of the discharge, and collect data every set time; Step 13, calculate the voltage of each battery string: Vn=vn+1-vn, forming a standard voltage curve A of each battery string in the battery system at the end of discharge; Step 14: Set the battery voltage change safety threshold β.

3. The method for online battery status evaluation according to claim 1 or 2, It is characterized in that The step 1 specifically includes: entering the standard voltage curve A and the battery voltage change safety threshold β into the battery management system BMS.

4. The method for online battery status evaluation according to claim 3, It is characterized in that The battery system to be tested is connected to a battery management system BMS via a voltage sampling line.

5. A battery status online evaluation system, It is characterized in that The following steps are involved: The comparison data building module is used to collect the voltage information of each battery string in a battery system in good health, form a standard voltage curve A, and set a battery voltage change safety threshold β; The data acquisition module of the battery system to be tested is used to obtain the voltage distribution curve a of the battery system to be tested at the end of discharge; A comparison module is used to compare curve a with the curve A, that is, curve A-curve a to obtain a comparison curve B composed of ΔV1, ΔV2, ΔV3---ΔVn; wherein n represents the nth string of batteries in the battery system to be tested; A calculation module is used to calculate the average value of the comparison curve B, ΔVave = (ΔV1 + ΔV2 + ΔV3 + --- ΔVn) / n, and then calculate the voltage fluctuation value b of the nth string of batteries, b = ΔVn - ΔVave; An evaluation module, if ±b < β, it is determined to be safe, otherwise it is determined that the nth string of batteries is faulty; if it is found that the nth string of batteries is faulty, the voltage fluctuation values b collected in the previous and next times of the nth string of batteries are compared. If b shows an increasing or decreasing trend, it is determined that the nth string of batteries has a loose solder joint and the welding strength of the nth string of batteries needs to be increased; otherwise, it is determined that the nth string of batteries is damaged and needs to be replaced.

6. The battery state online evaluation system according to claim 5, characterized in that, The specific execution process of the comparison data construction module is as follows: Step 11: Select a battery system with good health status, and arrange voltage sampling lines at both ends of each string of batteries 1, 2, 3 ---- n in the battery system to collect the potential signals at both ends of the batteries; Step 12: Discharge the battery system with good health status and record the potentials vn+1 and vn on both sides of each string of batteries at specific time points at the end of the discharge. Data is collected every set time interval; Step 13: Calculate the voltage of each string of batteries: Vn = vn+1 - vn, and form the standard voltage curve A of each string of batteries in the battery system at the end of the discharge; Step 14: Set the battery voltage change safety threshold β.

7. The battery state online evaluation system according to claim 5 or 6, characterized in that, The standard voltage curve A and the battery voltage change safety threshold β are entered into the battery management system BMS in the comparison data construction module.

8. The battery state online evaluation system according to claim 7, characterized in that, The battery system to be tested is connected to the battery management system BMS through voltage sampling lines.

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