Method, system and device for monitoring battery short circuit

Abstract

The present invention provides a method, system and device for monitoring battery short circuits. The method comprises: receiving collected electrical signal information of all cells in each power battery; observing self-discharge and calculating the self-discharge rate based on the cell voltage in the electrical signal information of each cell after depolarization is completed, so as to determine whether the power battery containing the cell corresponding to the self-discharge rate has an internal short circuit; and providing feedback based on the result of determining that the power battery has an internal short circuit, so as to trigger an alarm process for the internal short circuit of the power battery. This solves the problem of how to accurately and efficiently monitor whether a power battery has a slight internal short circuit in a good static environment while taking into account operations. It provides static battery data collection and large data recording operations, improves the calculation method, thereby improving the accuracy and efficiency of power battery internal short circuit monitoring, and can take into account operations.

Description

Technical Field

[0001] The present invention relates to the technical field of battery short circuit monitoring, and in particular to a method, system and device for monitoring battery short circuit. Background Art

[0002] Internal short circuits in electric vehicle power batteries are a major cause of thermal runaway. A local short circuit within the battery can cause a rapid temperature increase, which in turn can lead to thermal runaway in more areas, ultimately causing failure of the entire cell or even the entire battery pack. When a battery experiences a severe internal short circuit, the local short circuit consumes power, causing a rapid drop in voltage, a rapid increase in temperature, and a rapid decrease in insulation resistance. Existing monitoring technology monitors the thermal runaway process in power batteries, with the battery management system (BMS) issuing an alarm when thermal runaway occurs. However, by this point, the situation has already seriously threatened the safety of the vehicle and its passengers.

[0003] Before a serious internal short circuit occurs in a power battery, a slight internal short circuit has already occurred, which will consume additional power from the power battery and cause the voltage to drop slowly. By monitoring the changes in the power battery voltage under long-term quasi-static conditions, a slight internal short circuit of the power battery can be detected. However, usually, the power battery is on the vehicle side. When the power battery is in use, a large number of electrical appliances will be running to generate power interference, or the data collected and uploaded to the power battery during parking is relatively small. It is difficult to monitor the changes in the long-term static power battery, and it is also impossible to obtain accurate monitoring results through the extremely limited computing and analysis capabilities of the BMS on a limited amount of data.

[0004] Therefore, it makes sense to choose an environment where power batteries are often placed and can provide continuous and stable battery testing under static conditions for a long time. Summary of the Invention

[0005] In order to overcome the above-mentioned defects, the present invention is proposed to provide a method, system and device for monitoring battery short circuits, which solve or at least partially solve the problem of how to accurately and efficiently monitor slight internal short circuits of power batteries.

[0006] In a first aspect, a method for monitoring battery short circuits is provided, comprising: receiving collected electrical signal information of all cells in each power battery; observing self-discharge and calculating a self-discharge rate based on the cell voltage in the electrical signal information of each cell after depolarization is completed, so as to determine whether the power battery containing the cell corresponding to the self-discharge rate has an internal short circuit; and triggering an alarm process for the existence of an internal short circuit in the power battery based on feedback of the result of determining that the power battery has an internal short circuit.

[0007] Among them, the "receiving and collecting electrical signal information of all battery cells in each power battery" specifically includes: the power battery is placed at a battery swap station for a long time, and the battery swap station end collects the electrical signal information of all battery cells in each power battery stored in the battery swap station in real time; the real-time collection includes: collecting the electrical signal information of all battery cells of each power battery during the charging process at the battery swap station and after charging is completed while it is stationary at the battery swap station; wherein the electrical signal information of each battery cell includes at least: single cell voltage, current, temperature, and state of charge soc; the battery swap station end uploads the collected electrical signal information of all battery cells of each power battery to the cloud or the local control device of the battery swap station for synchronization; the cloud or the local control device of the battery swap station receives the electrical signal information and stores it corresponding to the collection time of real-time collection.

[0008] Among them, the "self-discharge observation and calculation of the self-discharge rate according to the cell voltage in the electrical signal information of each cell after depolarization is completed, so as to determine whether there is an internal short circuit in the power battery where the cell corresponding to the self-discharge rate is located" specifically includes: determining the time when the power battery where the cell is located stops charging according to the acquisition time of the electrical signal information corresponding to each cell; selecting the starting time for the first stage of self-discharge observation and calculation of the cell voltage of each cell in the power battery according to the time when the power battery stops charging and the depolarization time corresponding to the type of the power battery; starting from the starting time, observing and calculating the self-discharge rate of each cell in the power battery The cell voltage of the battery cell is subjected to first-stage self-discharge observation and calculation to obtain the first-stage self-discharge rate of each battery cell; based on the first-stage self-discharge rate of each battery cell, it is judged whether the power battery where the battery cell is located is subjected to second-stage self-discharge observation and calculation; if the judgment is yes, after the first-stage self-discharge observation and calculation is completed, the cell voltage of each battery cell of the power battery is subjected to second-stage self-discharge observation and calculation for a time length greater than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each battery cell; based on the second-stage self-discharge rate of each battery cell, it is judged whether the power battery where the battery cell is located has an internal short circuit.

[0009] Among them, the "determining the time to stop charging the power battery in which the power battery is located based on the acquisition time of the electrical signal information corresponding to each battery cell" specifically includes: finding the time when the current of all battery cells in the power battery is 0 from the electrical signal information in the order of the corresponding acquisition times as the time to stop charging; the "selecting the starting time for starting the first stage of self-discharge observation and calculation of the battery voltage of each battery cell in the power battery based on the time when the power battery stops charging and the depolarization time corresponding to the type of the power battery" specifically includes: each type of the power battery corresponds to a depolarization time determined after the test; selecting a time point greater than the time to stop charging plus the length of the depolarization time as the starting time for completing depolarization and conducting the first stage of self-discharge observation and calculation of the battery voltage of each battery cell in the power battery.

[0010] The “starting from the starting time, performing first-stage self-discharge observation and calculation on the cell voltage of each cell in the power battery to obtain the first-stage self-discharge rate of each cell” specifically includes: calculating the first-stage self-discharge rate p1Sdr1 of the observed j-th cell within the time length P1_time of the first-stage self-discharge observation and calculation:

[0011]

[0012] Among them, v i,j is the cell voltage of the jth cell at time ti, v 1,j is the cell voltage of the jth cell at time t1, t i,j Indicates the j-th cell ti moment, t 1,j Indicates t i,j The j-th battery cell before the moment t1.

[0013] The first-stage self-discharge rate p1Sdr1 of the observed j-th battery cell is calculated within the time length P1_time of the first-stage self-discharge observation and calculation, specifically including: if the observation end time point ti is less than the observation start time point t1+P1_time, then the battery cell voltage of the j-th battery cell from t1 to t1+P1_time is selected for observation, and the first-stage self-discharge rate p1Sdr of the j-th battery cell is calculated:

[0014]

[0015] in, It represents the time ti selected from the period from t1 to t1+P1_time for observing the cell voltage of the j-th cell. At this time, the corresponding cell voltage of the j-th cell is It represents the time selected from t1 to t1+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time t1, the corresponding cell voltage of the j-th cell is

[0016] If the observation end time point ti> the observation start time point t1+P1_time, then the cell voltage of the j-th cell from ti to ti+P1_time is selected for observation, and the first-stage self-discharge rate p1Sdr of the j-th cell is calculated:

[0017]

[0018] in, It represents the time ti selected during the period from ti to ti+P1_time for observing the cell voltage of the j-th cell. At this time, the cell voltage of the j-th cell is It represents the time selected from ti to ti+P1_time during which the cell voltage of the j-th cell is observed earlier than t as the beginning i -P1time, the corresponding cell voltage of the j-th cell is

[0019] The “starting from the starting time, performing a first-stage self-discharge observation and calculation on the cell voltage of each cell in the power battery to obtain a first-stage self-discharge rate of each cell” specifically includes: performing a linear fitting calculation on all cell voltages of the j-th cell within the time length P1_time of the first-stage self-discharge observation and calculation:

[0020] v^=v0+kt i Formula 5

[0021] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr1.

[0022] Among them, the "determining whether the power battery where the battery cell is located is to perform second-stage self-discharge observation and calculation based on the first-stage self-discharge rate of each battery cell" specifically includes: comparing the first-stage self-discharge rate p1Sdr or sdr1 of each battery cell with the first threshold value s1; when the first-stage self-discharge rate p1Sdr of the battery cell is greater than the first threshold value s1 or sdr1 is greater than the first threshold value s1, it is determined that the power battery where the battery cell is located is to perform second-stage self-discharge observation and calculation; when the first-stage self-discharge rate p1Sdr of the battery cell is less than or equal to the first threshold value s1 or sdr1 is less than or equal to the first threshold value s1, it is determined that there is no internal short circuit risk in the power battery where the battery cell is located and it is flowing normally.

[0023] Among them, the "if the judgment is yes, then after the first stage self-discharge observation and calculation is completed, the second stage self-discharge observation and calculation of the cell voltage of each cell of the power battery is started for a time length greater than the first stage self-discharge observation and calculation, to obtain the second stage self-discharge rate of each cell" specifically includes: after the first stage self-discharge observation and calculation is completed, the second stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second stage self-discharge observation and calculation, wherein the self-discharge rate p2Sdr of the jth cell is calculated within the time length P2_time of the second stage self-discharge observation and calculation:

[0024]

[0025] Among them, t i+P2_time,j It represents the time period from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed. i+P2_time At this moment, the cell voltage of the jth cell is v i+P2_time,j ;t i,j It represents the time from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed earlier than t i+P2_time t i At this moment, the cell voltage of the jth cell is v i,j ; wherein, the time length P2_time of the second stage self-discharge observation and calculation is n times the time length P1_time of the first stage self-discharge observation and calculation, n∈[2,10].

[0026] Among them, the "if the judgment is yes, then after the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation of the cell voltage of each cell of the power battery is started for a time length greater than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each cell" specifically includes: after the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation, and within the time length P2_time of the second-stage self-discharge observation and calculation, all cell voltages of the j-th cell are linearly fitted and calculated:

[0027] v^=v0+kt i Formula 5

[0028] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr2.

[0029] Among them, the "determining whether the power battery where the battery cell is located has an internal short circuit based on the second-stage self-discharge rate of each battery cell" specifically includes: comparing the second-stage self-discharge rate p2Sdr or sdr2 of each battery cell with the second threshold value s2; when the second-stage self-discharge rate p2Sdr of the battery cell is greater than the second threshold value s2 or sdr2 is greater than the second threshold value s2, it is determined that the power battery where the battery cell is located has an internal short circuit; when the second-stage self-discharge rate p2Sdr of the battery cell is less than or equal to the second threshold value s2 or sdr2 is less than or equal to s2, it is determined that the power battery where the battery cell is located has no internal short circuit risk and is flowing normally; wherein, the pre-set first threshold value s1>the second threshold value s2>the battery cell self-discharge specification, and the value range of s1 and s2 is 0.1~100.

[0030] Among them, the "feedback based on the result of determining that the power battery has an internal short circuit to trigger an alarm processing for the existence of an internal short circuit in the power battery" specifically includes: after the cloud or the local control equipment of the battery swap station completes the observation and calculation of each stage, the result of whether the power battery has an internal short circuit is fed back to the corresponding battery swap station; when the result received by the battery swap station is that the power battery has an internal short circuit, the battery swap station triggers an alarm processing for the existence of an internal short circuit in the power battery, including: alarm, stop using and start the return and repair process.

[0031] In a second aspect, a system for monitoring battery short circuits is provided, comprising: a receiving storage device for receiving collected electrical signal information of all cells in each power battery; a staged calculation device for observing self-discharge and calculating a self-discharge rate based on the cell voltage in the electrical signal information of each cell after depolarization is completed, so as to determine whether the power battery in which the cell corresponding to the self-discharge rate is located has an internal short circuit; and an alarm device for triggering an alarm processing for the existence of an internal short circuit in the power battery based on feedback of a result of determining that the power battery has an internal short circuit.

[0032] Among them, the receiving and storage device specifically includes: the power battery is placed at a battery swap station for a long time, and the battery swap station end collects the electrical signal information of all battery cells in each power battery stored in the battery swap station in real time; the real-time collection includes: collecting the electrical signal information of all battery cells of each power battery during the charging process at the battery swap station and after charging is completed while the battery is placed at the battery swap station; wherein the electrical signal information of each battery cell includes at least: single cell voltage, current, temperature, and state of charge soc; the battery swap station end uploads the collected electrical signal information of all battery cells of each power battery to the cloud or the local control device of the battery swap station for synchronization; the cloud or the local control device of the battery swap station receives the electrical signal information and stores it corresponding to the collection time of real-time collection.

[0033] The staged calculation device specifically includes: a charging stop time device for determining the time when the power battery in which the battery cell is located stops charging according to the acquisition time of the electrical signal information corresponding to each battery cell; a first stage start selection device for selecting the start time for starting the first stage self-discharge observation and calculation of the battery cell voltage of each battery cell in the power battery according to the time when the power battery stops charging and the depolarization time corresponding to the type of the power battery; a first stage calculation device for performing the first stage self-discharge observation and calculation of the battery cell voltage of each battery cell in the power battery starting from the start time. , obtaining the first-stage self-discharge rate of each battery cell; judging whether the power battery where the battery cell is located is to perform second-stage self-discharge observation and calculation according to the first-stage self-discharge rate of each battery cell; the second-stage calculation device is used for, if the judgment is yes, starting the second-stage self-discharge observation and calculation of the battery cell voltage of each battery cell of the power battery for a time length greater than the first-stage self-discharge observation and calculation after the first-stage self-discharge observation and calculation is completed, to obtain the second-stage self-discharge rate of each battery cell; judging whether the power battery where the battery cell is located has an internal short circuit according to the second-stage self-discharge rate of each battery cell.

[0034] Among them, the charging stop time device specifically includes: finding the time when the current of all cells in the power battery is zero from the electrical signal information in the order of the corresponding collection time as the charging stop time; the first stage start selection device specifically includes: each type of the power battery corresponds to a depolarization time determined after the test; and selecting a time point greater than the charging stop time plus the length of the depolarization time as the starting time for completing depolarization and performing the first stage self-discharge observation and calculation of the cell voltage of each cell in the power battery.

[0035] The first-stage calculation device specifically includes: calculating the first-stage self-discharge rate p1Sdr1 of the observed j-th battery cell within the first-stage self-discharge observation and calculation time length P1_time:

[0036]

[0037] Among them, v i,j is the cell voltage of the jth cell at time ti, v 1,j is the cell voltage of the jth cell at time t1, t i,j Indicates the j-th cell ti moment, t 1,j Indicates t i,j The j-th battery cell before the moment t1.

[0038] The first-stage calculation device further includes: if the observation end time point ti is less than the observation start time point t1+P1_time, then selecting the cell voltage of the j-th cell from t1 to t1+P1_time for observation, and calculating the first-stage self-discharge rate p1Sdr of the j-th cell:

[0039]

[0040] in, It represents the time ti selected from the period from t1 to t1+P1_time for observing the cell voltage of the j-th cell. At this time, the corresponding cell voltage of the j-th cell is It represents the time selected from t1 to t1+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time t1, the corresponding cell voltage of the j-th cell is

[0041] If the observation end time point ti> the observation start time point t1+P1_time, then the cell voltage of the j-th cell from ti to ti+P1_time is selected for observation, and the first-stage self-discharge rate p1Sdr of the j-th cell is calculated:

[0042]

[0043] in, It represents the time ti selected during the period from ti to ti+P1_time for observing the cell voltage of the j-th cell. At this time, the cell voltage of the j-th cell is It represents the time selected from ti to ti+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time ti-P1_time, the corresponding cell voltage of the j-th cell is

[0044] The first-stage calculation device specifically includes: performing linear fitting calculation on all cell voltages of the j-th cell within the time length P1_time of the first-stage self-discharge observation and calculation:

[0045] v^=v0+kt i Formula 5

[0046] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, ti is the end time point of this period, and the slope k = self-discharge rate sdr1.

[0047] Among them, the first-stage calculation device specifically includes: comparing the first-stage self-discharge rate p1Sdr or sdr1 of each battery cell with the first threshold value s1; when the first-stage self-discharge rate p1Sdr of the battery cell is greater than the first threshold value s1 or sdr1 is greater than the first threshold value s1, it is judged that the power battery where the battery cell is located is to perform second-stage self-discharge observation and calculation; when the first-stage self-discharge rate p1Sdr of the battery cell is less than or equal to the first threshold value s1 or sdr1 is less than or equal to the first threshold value s1, it is judged that the power battery where the battery cell is located does not have an internal short circuit risk and is flowing normally.

[0048] The second-stage calculation device specifically includes: after the first-stage self-discharge observation and calculation are completed, performing the second-stage self-discharge observation and calculation on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation, wherein the self-discharge rate p2Sdr of the j-th cell is calculated within the time length P2_time of the second-stage self-discharge observation and calculation:

[0049]

[0050] Among them, t i+P2_time,j It represents the time period from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed. i+P2_time At this moment, the cell voltage of the jth cell is v i+P2_time,j ;t i,j It represents the time from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed earlier than t i+P2_time t i At this moment, the cell voltage of the jth cell is v i,j ; wherein, the time length P2_time of the second stage self-discharge observation and calculation is n times the time length P1_time of the first stage self-discharge observation and calculation, n∈[2,10].

[0051] The second-stage calculation device specifically includes: after the first-stage self-discharge observation and calculation is completed, performing the second-stage self-discharge observation and calculation on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation, and performing a linear fitting calculation on all cell voltages of the j-th cell within the time length P2_time of the second-stage self-discharge observation and calculation:

[0052] v^=v0+kt i Formula 5

[0053] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr2.

[0054] Among them, the second-stage calculation device also includes: comparing the second-stage self-discharge rate p2Sdr or sdr2 of each battery cell with the second threshold s2; when the second-stage self-discharge rate p2Sdr of the battery cell is greater than the second threshold s2 or sdr2 is greater than the second threshold s2, it is judged that the power battery where the battery cell is located has an internal short circuit; when the second-stage self-discharge rate p2Sdr of the battery cell is less than or equal to the second threshold s2 or sdr2 is less than or equal to s2, it is judged that the power battery where the battery cell is located does not have an internal short circuit risk and is flowing normally; wherein, the pre-set first threshold s1>the second threshold s2>the battery cell self-discharge specification, and the value range of s1 and s2 is 0.1~100.

[0055] Among them, the alarm device specifically includes: after the cloud or the local control equipment of the battery swap station completes the observation and calculation of each stage, the result of whether the power battery has an internal short circuit is fed back to the corresponding battery swap station. When the result received by the battery swap station is that the power battery has an internal short circuit, the battery swap station triggers the alarm processing of the internal short circuit of the power battery, including: alarm, stop using and start the return and repair process.

[0056] According to a third aspect, a storage device is provided, wherein a plurality of program codes are stored therein, wherein the program codes are suitable for being loaded and run by a processor to execute any one of the above methods for monitoring battery short circuits.

[0057] In a fourth aspect, a control device is provided, comprising a processor and a storage device, wherein the storage device is suitable for storing a plurality of program codes, and the program codes are suitable for being loaded and run by the processor to execute any one of the above-mentioned methods for monitoring battery short circuits.

[0058] Solution 1: A method for monitoring battery short circuit, comprising:

[0059] Receive and collect electrical signal information from all cells in each power battery;

[0060] Observe the self-discharge and calculate the self-discharge rate based on the cell voltage in the electrical signal information of each cell after depolarization is completed, so as to determine whether the power battery in which the cell corresponding to the self-discharge rate is located has an internal short circuit;

[0061] According to the result of determining that the power battery has an internal short circuit, an alarm process for the internal short circuit of the power battery is triggered.

[0062] Solution 2: The method according to Solution 1, characterized in that the step of "receiving and collecting electrical signal information of all cells in each power battery" specifically includes:

[0063] The power battery is kept at a battery swap station for a long time, and the battery swap station collects the electrical signal information of all cells in each power battery stored at the battery swap station in real time;

[0064] The real-time collection includes: collecting electrical signal information of all cells of each power battery during the charging process at the battery swap station and during the static process at the battery swap station after charging is completed;

[0065] The electrical signal information of each battery cell includes at least: single cell voltage, current, temperature, and state of charge (SOC);

[0066] The battery swap station uploads and synchronizes the collected electrical signal information of all cells of each power battery to the cloud or the local control device of the battery swap station;

[0067] The cloud or local control equipment of the battery swap station receives the electrical signal information and stores it corresponding to the collection time of real-time collection.

[0068] Solution 3. The method according to Solution 2 is characterized in that the step of "observing self-discharge and calculating the self-discharge rate based on the cell voltage in the electrical signal information of each cell after depolarization to determine whether the power battery containing the cell corresponding to the self-discharge rate has an internal short circuit" specifically includes:

[0069] Determining, based on the acquisition time of the electrical signal information corresponding to each battery cell, a time at which the power battery in which the battery cell is located stops charging;

[0070] Selecting a starting time for starting the first stage of self-discharge observation and calculation of the cell voltage of each cell in the power battery according to the time when the power battery stops charging and the depolarization time corresponding to the type of the power battery;

[0071] Starting from the starting time, observing and calculating the cell voltage of each cell in the power battery during the first stage of self-discharge to obtain a first stage self-discharge rate of each cell;

[0072] Determining, based on the first-stage self-discharge rate of each battery cell, whether the power battery in which the battery cell is located should perform second-stage self-discharge observation and calculation;

[0073] If the answer is yes, after the first-stage self-discharge observation and calculation is completed, a second-stage self-discharge observation and calculation is started for the cell voltage of each cell of the power battery for a time period longer than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each cell;

[0074] According to the second-stage self-discharge rate of each battery cell, it is determined whether the power battery in which the battery cell is located has an internal short circuit.

[0075] Solution 4: The method according to Solution 3, characterized in that:

[0076] The “determining the time to stop charging the power battery in which the battery cell is located based on the acquisition time of the electrical signal information corresponding to each battery cell” specifically includes:

[0077] For all cells in the power battery, according to the order of the corresponding collection times, finding the time when the current of all cells is zero from the electrical signal information as the time to stop charging;

[0078] The step of “selecting a starting time for observing and calculating the first stage of self-discharge of the cell voltage of each cell in the power battery based on the time when charging of the power battery is stopped and the depolarization time corresponding to the type of the power battery” specifically includes:

[0079] Each type of power battery has a corresponding depolarization time determined after testing;

[0080] A time point that is longer than the charging stop time plus the depolarization time is selected as the starting time for completing depolarization and performing the first stage self-discharge observation and calculation of the cell voltage of each cell in the power battery.

[0081] Solution 5. The method according to Solution 4 is characterized in that the step of "observing and calculating the first-stage self-discharge of the cell voltage of each cell in the power battery from the start time to obtain the first-stage self-discharge rate of each cell" specifically includes:

[0082] During the first stage of self-discharge observation and calculation time length P1_time, calculate the first stage self-discharge rate p1Sdr1 of the observed j-th battery cell:

[0083]

[0084] Among them, v i,j is the cell voltage of the jth cell at time ti, v 1,j is the cell voltage of the jth cell at time t1, t i,j Indicates the j-th cell ti moment, t 1,j Indicates t i,j The j-th battery cell before the moment t1.

[0085] Solution 6: The method according to Solution 5 is characterized in that the calculation of the observed first-stage self-discharge rate p1Sdr1 of the j-th battery cell within the time length P1_time of the first-stage self-discharge observation and calculation specifically includes:

[0086] If the observation end time point ti is less than the observation start time point t1+P1_time, the cell voltage of the j-th cell from t1 to t1+P1_time is selected for observation, and the self-discharge rate p1Sdr of the j-th cell in the first stage is calculated:

[0087]

[0088] in, It represents the time ti selected from the period from t1 to t1+P1_time for observing the cell voltage of the j-th cell. At this time, the corresponding cell voltage of the j-th cell is It represents the time selected from t1 to t1+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time t1, the corresponding cell voltage of the j-th cell is

[0089] If the observation end time point ti> the observation start time point t1+P1_time, then the cell voltage of the j-th cell from ti to ti+P1_time is selected for observation, and the first-stage self-discharge rate p1Sdr of the j-th cell is calculated:

[0090]

[0091] in, It represents the time ti selected during the period from ti to ti+P1_time for observing the cell voltage of the j-th cell. At this time, the cell voltage of the j-th cell is It represents the time selected from ti to ti+P1_time during which the cell voltage of the j-th cell is observed earlier than t as the beginning i -P1_time, the corresponding cell voltage of the j-th cell is

[0092] Solution 7: The method according to Solution 4 is characterized in that the step of "observing and calculating the first-stage self-discharge of the cell voltage of each cell in the power battery from the start time to obtain the first-stage self-discharge rate of each cell" specifically includes:

[0093] During the first stage of self-discharge observation and calculation, P1_time, all cell voltages of the j-th cell are linearly fitted and calculated:

[0094] v^=v0+kt i Formula 5

[0095] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr1.

[0096] Solution 8. According to the method of Solution 5, 6, or 7, “determining whether the power battery in which the battery cell is located should perform second-stage self-discharge observation and calculation based on the first-stage self-discharge rate of each battery cell” specifically includes:

[0097] Compare the first-stage self-discharge rate p1Sdr or sdr1 of each battery cell with a first threshold s1;

[0098] When the first-stage self-discharge rate p1Sdr of the battery cell is greater than the first threshold s1 or sdr1 is greater than the first threshold s1, it is determined that the power battery in which the battery cell is located is to perform the second-stage self-discharge observation and calculation;

[0099] When the first-stage self-discharge rate p1Sdr of the battery cell is less than or equal to the first threshold s1 or sdr1 is less than or equal to the first threshold s1, it is determined that the power battery in which the battery cell is located has no internal short circuit risk and operates normally.

[0100] Solution 9. The method according to Solution 8 is characterized in that the step of "if the judgment is yes, then after the first-stage self-discharge observation and calculation is completed, starting the second-stage self-discharge observation and calculation of the cell voltage of each cell of the power battery for a time length greater than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each cell" specifically includes:

[0101] After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation, wherein the self-discharge rate p2Sdr of the j-th cell is calculated within the time length P2_time of the second-stage self-discharge observation and calculation:

[0102]

[0103] Among them, t i+P2_time,j It represents the time period from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed. i+P2_time At this moment, the cell voltage of the jth cell is v i+P2_time,j ;t i,j It represents the time from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed earlier than t i+P2_time t i At this moment, the cell voltage of the jth cell is v i,j ;

[0104] The time length P2_time of the second stage self-discharge observation and calculation is n times the time length P1_time of the first stage self-discharge observation and calculation, where n∈[2,10].

[0105] Solution 10: The method according to Solution 8, characterized in that the step of "if the judgment is yes, then after the first-stage self-discharge observation and calculation is completed, starting the second-stage self-discharge observation and calculation of the cell voltage of each cell of the power battery for a time period longer than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each cell" specifically includes:

[0106] After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation. Within the time length P2_time of the second-stage self-discharge observation and calculation, all cell voltages of the j-th cell are linearly fitted and calculated:

[0107] v^=v0+kt i Formula 5

[0108] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr2.

[0109] Solution 11: The method according to Solution 9 or 10, characterized in that the step of “determining whether the power battery in which the battery cell is located has an internal short circuit based on the second-stage self-discharge rate of each battery cell” specifically includes:

[0110] Comparing the second-stage self-discharge rate p2Sdr or sdr2 of each battery cell with a second threshold s2;

[0111] When the second-stage self-discharge rate p2Sdr of the battery cell is greater than the second threshold s2 or sdr2 is greater than the second threshold s2, it is determined that the power battery in which the battery cell is located has an internal short circuit;

[0112] When the second-stage self-discharge rate p2Sdr of the battery cell is less than or equal to the second threshold s2 or sdr2 is less than or equal to s2, it is determined that the power battery in which the battery cell is located does not have an internal short circuit risk and is in normal operation;

[0113] The preset first threshold s1>the second threshold s2>the cell self-discharge specification, and the value range of s1 and s2 is 0.1-100.

[0114] Solution 12: The method according to Solution 11, characterized in that the step of "feeding back the result of determining that the power battery has an internal short circuit to trigger an alarm process for the power battery having an internal short circuit" specifically includes:

[0115] After the cloud or local control equipment at the battery swap station completes the observation and calculation at each stage, it will feedback the result of whether the power battery has an internal short circuit to the corresponding battery swap station.

[0116] When the result received by the battery swap station is that the power battery has an internal short circuit, the battery swap station triggers an alarm process for the internal short circuit of the power battery, including: alarming, stopping use and initiating a return and repair process.

[0117] Solution 13: A system for monitoring battery short circuits, comprising:

[0118] A receiving storage device, used to receive the collected electrical signal information of all cells in each power battery;

[0119] A staged calculation device is used to observe the self-discharge and calculate the self-discharge rate based on the cell voltage in the electrical signal information of each cell after depolarization is completed, so as to determine whether the power battery in which the cell corresponding to the self-discharge rate is located has an internal short circuit;

[0120] The alarm device triggers an alarm process for the internal short circuit of the power battery based on feedback of a result of determining that the power battery has an internal short circuit.

[0121] Solution 14: The system according to Solution 13, wherein the receiving and storing device specifically includes:

[0122] The power battery is kept at a battery swap station for a long time, and the battery swap station collects the electrical signal information of all cells in each power battery stored at the battery swap station in real time;

[0123] The real-time collection includes: collecting electrical signal information of all cells of each power battery during the charging process at the battery swap station and during the static process at the battery swap station after charging is completed;

[0124] The electrical signal information of each battery cell includes at least: single cell voltage, current, temperature, and state of charge (SOC);

[0125] The battery swap station uploads and synchronizes the collected electrical signal information of all cells of each power battery to the cloud or the local control device of the battery swap station;

[0126] The cloud or local control equipment of the battery swap station receives the electrical signal information and stores it corresponding to the collection time of real-time collection.

[0127] Solution 15: The system according to Solution 14, wherein the phased calculation device specifically includes:

[0128] A charging stop time device, used to determine the time to stop charging the power battery in which the battery cell is located according to the acquisition time of the electrical signal information corresponding to each battery cell;

[0129] a first-stage starting device for selecting, based on the time when charging of the power battery is stopped and the depolarization time corresponding to the type of the power battery, a starting time for observing and calculating the first-stage self-discharge of the cell voltage of each cell in the power battery;

[0130] a first-stage calculation device for performing a first-stage self-discharge observation and calculation on the cell voltage of each cell in the power battery starting from the start time to obtain a first-stage self-discharge rate of each cell; and determining, based on the first-stage self-discharge rate of each cell, whether the power battery in which the cell is located should perform a second-stage self-discharge observation and calculation;

[0131] The second-stage calculation device is used to, if the judgment is yes, start the second-stage self-discharge observation and calculation of the cell voltage of each battery cell of the power battery for a time length greater than the first-stage self-discharge observation and calculation after the first-stage self-discharge observation and calculation is completed, to obtain the second-stage self-discharge rate of each battery cell; and judge whether the power battery in which the battery cell is located has an internal short circuit based on the second-stage self-discharge rate of each battery cell.

[0132] Solution 16: The system according to Solution 15, characterized in that:

[0133] The device for stopping charging specifically comprises: finding the time when the current of all cells in the power battery is 0 from the electrical signal information in the order of the corresponding collection time as the time to stop charging;

[0134] The device for selecting the start of the first stage specifically includes: a depolarization time determined after testing corresponding to each type of the power battery; selecting a time point greater than the time of stopping charging plus the length of the depolarization time as the starting time for completing depolarization and performing the first stage self-discharge observation and calculation of the cell voltage of each cell in the power battery.

[0135] Solution 17: The system according to Solution 16, wherein the first-stage computing device specifically includes:

[0136] During the first stage of self-discharge observation and calculation time length P1_time, calculate the first stage self-discharge rate p1Sdr1 of the observed j-th battery cell:

[0137]

[0138] Among them, v i,j is the cell voltage of the jth cell at time ti, v 1,j is the cell voltage of the jth cell at time t1, t i,j Indicates the j-th cell ti moment, t 1,j Indicates t i,j The j-th battery cell before the moment t1.

[0139] Solution 18. The system according to Solution 17, wherein the first-stage computing device further comprises:

[0140] If the observation end time point ti is less than the observation start time point t1+P1_time, the cell voltage of the j-th cell from t1 to t1+P1_time is selected for observation, and the self-discharge rate p1Sdr of the j-th cell in the first stage is calculated:

[0141]

[0142] in, It represents the time ti selected from the period from t1 to t1+P1_time for observing the cell voltage of the j-th cell. At this time, the corresponding cell voltage of the j-th cell is It represents the time selected from t1 to t1+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time t1, the corresponding cell voltage of the j-th cell is

[0143] If the observation end time point ti> the observation start time point t1+P1_time, then the cell voltage of the j-th cell from ti to ti+P1_time is selected for observation, and the first-stage self-discharge rate p1Sdr of the j-th cell is calculated:

[0144]

[0145] in, It represents the time ti selected during the period from ti to ti+P1_time for observing the cell voltage of the j-th cell. At this time, the cell voltage of the j-th cell is It represents the time selected from ti to ti+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time ti-P1_time, the corresponding cell voltage of the j-th cell is

[0146] Solution 19: The system according to Solution 16, wherein the first-stage computing device specifically includes:

[0147] During the first stage of self-discharge observation and calculation, P1_time, all cell voltages of the j-th cell are linearly fitted and calculated:

[0148] v^=v0+kt i Formula 5

[0149] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, ti is the end time point of this period, and the slope k = self-discharge rate sdr1.

[0150] Solution 20: The system according to Solution 17, 18, or 19, wherein the first-stage computing device specifically includes:

[0151] Compare the first-stage self-discharge rate p1Sdr or sdr1 of each battery cell with a first threshold s1;

[0152] When the first-stage self-discharge rate p1Sdr of the battery cell is greater than the first threshold s1 or sdr1 is greater than the first threshold s1, it is determined that the power battery in which the battery cell is located is to perform the second-stage self-discharge observation and calculation;

[0153] When the first-stage self-discharge rate p1Sdr of the battery cell is less than or equal to the first threshold s1 or sdr1 is less than or equal to the first threshold s1, it is determined that the power battery in which the battery cell is located has no internal short circuit risk and operates normally.

[0154] Solution 21. The system according to Solution 20, wherein the second-stage computing device specifically includes:

[0155] After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation, wherein the self-discharge rate p2Sdr of the j-th cell is calculated within the time length P2_time of the second-stage self-discharge observation and calculation:

[0156]

[0157] Among them, t i+P2_time,jIt represents the time period from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed. i+P2_time At this moment, the cell voltage of the jth cell is v i+P2_time,j ;t i,j It represents the time from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed earlier than t i+P2_time t i At this moment, the cell voltage of the jth cell is v i,j ;

[0158] The time length P2_time of the second stage self-discharge observation and calculation is n times the time length P1_time of the first stage self-discharge observation and calculation, where n∈[2,10].

[0159] Solution 22: According to the system of Solution 20, the second-stage computing device specifically includes:

[0160] After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation. Within the time length P2_time of the second-stage self-discharge observation and calculation, all cell voltages of the j-th cell are linearly fitted and calculated:

[0161] v^=v0+kt i Formula 5

[0162] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr2.

[0163] Solution 23. The system according to Solution 20 or 21, wherein the second-stage computing device further includes:

[0164] Comparing the second-stage self-discharge rate p2Sdr or sdr2 of each battery cell with a second threshold s2;

[0165] When the second-stage self-discharge rate p2Sdr of the battery cell is greater than the second threshold s2 or sdr2 is greater than the second threshold s2, it is determined that the power battery in which the battery cell is located has an internal short circuit;

[0166] When the second-stage self-discharge rate p2Sdr of the battery cell is less than or equal to the second threshold s2 or sdr2 is less than or equal to s2, it is determined that the power battery in which the battery cell is located does not have an internal short circuit risk and is in normal operation;

[0167] The preset first threshold s1>the second threshold s2>the cell self-discharge specification, and the value range of s1 and s2 is 0.1-100.

[0168] Solution 24: The system according to Solution 23, wherein the alarm device specifically comprises:

[0169] After the cloud or local control equipment at the battery swap station completes the observation and calculation at each stage, it will feedback the result of whether the power battery has an internal short circuit to the corresponding battery swap station.

[0170] When the result received by the battery swap station is that the power battery has an internal short circuit, the battery swap station triggers an alarm process for the internal short circuit of the power battery, including: alarming, stopping use and initiating a return and repair process.

[0171] Solution 25. A storage device storing a plurality of program codes, wherein the program codes are suitable for being loaded and executed by a processor to execute the method for monitoring battery short circuit according to any one of Solutions 1 to 12.

[0172] Option 26. A control device comprising a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, characterized in that the program codes are suitable for being loaded and run by the processor to execute the method for monitoring battery short circuits according to any one of Options 1 to 12.

[0173] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0174] The present invention's battery short-circuit monitoring solution monitors and determines minor internal short circuits within a power battery. Specifically, the power battery is in a stable environment with few influencing factors, such as a battery swap station. The system collects electrical signal information from all of the power battery's cells and stores this large amount of data in chronological order. Using a large amount of stable and accurate long-term historical data under static conditions, the self-discharge of the power battery cells is observed and calculated in stages and steps. By comparing the self-discharge rate with a threshold, the system determines whether the power battery containing the cell has an internal short circuit. This allows for more accurate calculation results and a higher success rate in judgment.

[0175] Furthermore, the phased and step-by-step observation and calculation process is primarily divided into a first and second phase, with some steps incorporating a sliding window calculation approach. If the self-discharge rate calculated in the first phase of a power battery cell exceeds a threshold, the observation and calculation process is intercepted and entered into the second phase. The second phase of observation and calculation is then completed, and a determination is made as to whether the self-discharge rate calculated in the second phase exceeds the second threshold. If both exceed, a significant internal short circuit risk is considered, and an alarm is issued to initiate safety measures for the power battery. Otherwise, if the calculated self-discharge rate does not exceed either the first or second threshold at any phase, the power battery is deemed to have no internal short circuit risk and can be used normally. This balances calculation accuracy with the operational efficiency of the battery swap station. Furthermore, the sliding window approach can more accurately calculate the trend of monotonically changing curves, thereby saving computing resources and improving efficiency. This effectively and accurately implements real-time monitoring of power battery internal short circuits in a battery swap station-based environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0176] The specific embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0177] Figure 1 This is a schematic diagram of an application scenario of an embodiment of the technical solution for monitoring battery short circuits according to the present invention;

[0178] Figure 2 2 is a schematic diagram of voltage change curves of different power batteries after charging according to an embodiment of the solution of the present invention;

[0179] Figure 3 This is a flow chart of the main steps of an embodiment of a method for monitoring battery short circuit according to the present invention;

[0180] Figure 4 1 is a flow chart showing the main steps of a process for calculating the self-discharge rate according to an embodiment of the present invention;

[0181] Figure 5 This is a flow chart of the main steps of an application example of the method according to the present invention;

[0182] Figure 6 FIG. 4 is a structural block diagram of a system for monitoring battery short circuit according to the present invention. DETAILED DESCRIPTION

[0183] Some embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0184] In the description of the present invention, "module" and "processor" may include hardware, software, or a combination of both. A module may include hardware circuitry, various suitable sensors, communication ports, and memory. It may also include software components, such as program code, or a combination of software and hardware. A processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. A processor has data and / or signal processing capabilities. A processor may be implemented in software, hardware, or a combination of both. Non-transitory computer-readable storage media include any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, and the like. The term "A and / or B" refers to all possible combinations of A and B, such as only A, only B, or both A and B. The terms "at least one of A or B" or "at least one of A and B" have similar meanings to "A and / or B" and may include only A, only B, or both A and B. The singular forms "a," "the," and "an" may also include the plural forms.

[0185] Here we first explain some terms involved in the present invention.

[0186] Standing: After charging, the battery is placed still so that the internal electrode of the battery is in full contact with the electrolyte and the electrode is completely soaked. In this way, during the polarization process of the battery, a complete SEI film can be formed on the surface of the electrode. Only then will the battery have good electrical performance in the later stage, and the consistency of the single cells in the battery pack will also be improved (that is, the polarization voltage can be reduced and the battery voltage can be balanced).

[0187] Working condition: The working state of the equipment under conditions directly related to its operation.

[0188] Single cell is also known as battery cell: it is the basic battery unit that constitutes the power battery. Multiple single cells are connected in series and parallel to form a power battery.

[0189] Single cell voltage: the voltage of a single cell.

[0190] Ohmic polarization: also known as resistance polarization, refers to the polarization established by the ohmic voltage drop caused by the ohmic resistance of the electrode system when current flows through it. Ohmic polarization is mainly determined by the solution resistance and is related to the solution resistivity. The higher the resistivity, the higher the ohmic polarization. At the same time, ohmic polarization is related to the distance between the electrodes. When there is a diaphragm, it is also related to the thickness, number of layers, porosity, and tortuosity of the pores of the diaphragm. That is, ohmic polarization is related to the power battery system or structure. Ohmic polarization is proportional to the current.

[0191] Concentration polarization / electrochemical polarization: The polarization established by the change in interfacial potential difference caused by the change in interfacial charge distribution state due to the slow charge transfer process; its magnitude is determined by the electrochemical reaction rate and is related to the nature of the electrochemical reaction.

[0192] Self-discharge: The automatic discharge phenomenon of power batteries when they are left at rest or in an open circuit.

[0193] Self-discharge rate / self-discharge rate: The rate at which the power battery discharges automatically, indicating the speed of self-discharge.

[0194] In the existing technology, the power battery is usually placed on the end of the electric vehicle. During the parking process (the vehicle is stationary), the power battery is stationary. However, only a small amount of power battery data can be obtained by monitoring with the battery management system (BMS). In addition, the data storage capacity and computing power on the vehicle side are weak, and only a small amount of battery data in a short period of time can be judged. Therefore, the accuracy of the monitoring results is very low. If the power battery is in use, there will be interference caused by the use of a large number of electrical appliances, and it will be impossible to monitor and judge whether there is a short circuit in the power battery itself.

[0195] In one embodiment of the solution of the present invention, the environment of the battery swap station where the power battery is located is utilized. When the power battery is in a static working condition after charging, the battery swap station collects the self-discharge signal information of each power battery in real time, such as: collecting the self-discharge signal information of all single cells (battery cells) in each power battery and uploading it to the cloud; after depolarization is completed, the cloud performs the first stage of self-discharge observation and calculation by uploading the stored self-discharge signal information to determine whether the first self-discharge rate of the power battery exceeds the first threshold; if the first self-discharge rate exceeds the first threshold, the power battery will continue the second stage of self-discharge observation and calculation to determine whether the second self-discharge rate exceeds the second threshold. If it exceeds, it is determined that the power battery has a high risk of internal short circuit, thereby triggering subsequent processing.

[0196] See attached Figure 1 , Figure 1 The figure is a schematic diagram of an application scenario for an embodiment of the technical solution of the present invention. Before a power battery experiences a severe partial internal short circuit, it may already have experienced a minor internal short circuit, which consumes additional power and causes the voltage to slowly drop. By monitoring changes in the power battery voltage under long-term quasi-stationary operating conditions, a minor internal short circuit can be detected. Therefore, it is necessary to find an operating condition that can eliminate interference from additional electrical appliances, allow for long-term storage, and provide continuous real-time monitoring, in order to accurately obtain the required power battery internal short circuit condition (self-discharge rate / self-discharge ratio) required for calculation.

[0197] After determining multiple battery swap stations (such as Figure 1As shown in Figures 1, 2, ...v battery swap stations), each has the working conditions of long-term real-time monitoring of power batteries, long-term stationary power batteries, and no interference from other electrical appliances. Therefore, the self-discharge rate of the power batteries can be detected during the period when each power battery is not replaced and used in the electric vehicle and is left at the battery swap station to achieve real-time monitoring of whether the power battery has a high-risk internal short circuit. In other words, the power batteries stored in the battery swap station can be left at rest in the battery swap station environment to realize the solution of monitoring internal short circuits of the batteries. The battery swap station provides an environment where the power batteries can be kept at rest for a long time and their electrical signal information can be continuously collected.

[0198] like Figure 1 As shown, there are multiple battery swap stations 1, 2, ... v, and each battery swap station will store multiple power batteries to be replaced for electric vehicles for a long time. For example, battery swap station 1 stores multiple power batteries 1, 2, ... n, battery swap station 2 stores multiple power batteries 1, 2, ... m, ... battery swap station v stores multiple power batteries 1, 2, ... x, and so on. Among them, n, m, v, and x all represent numbers, which are natural numbers greater than 0. In one embodiment of the present invention, each battery swap station, taking one of the battery swap stations 1 as an example, can collect electrical signal information of each power battery 1, 2, ... n stored in the battery swap station 1 through a data acquisition device at the battery swap station end, such as a battery management system, a sensor with electrical signal acquisition, or other computer / electronic device / digital device with electrical signal acquisition function, etc. Specifically, since each power battery contains at least one or more cells, while the power battery is charging at the battery swap station, and while it is stationary after charging, the data acquisition device at the battery swap station can collect real-time electrical signal information for all cells in each power battery, including single-cell voltage, current, temperature, and state of charge (SOC), and upload it to the cloud for synchronous storage. Similarly, each battery swap station 1, 2, ..., v will each collect real-time electrical signal information for all cells in all stored power batteries, and synchronously upload it to the cloud for corresponding storage.

[0199] Furthermore, the cloud can store large amounts of data for a long time, and the cloud can also have multiple servers, server groups, etc., which can use these large amounts of stored data to perform accurate calculations to determine the self-discharge rate / self-discharge rate of each power battery stored in the corresponding battery swap station, and then determine whether the state of a power battery with the calculated corresponding self-discharge rate is in a situation with a large internal short circuit risk. Specifically, at the battery swap station, each power battery replaced from an electric vehicle will be charged; during the charging process, the battery swap station can collect electrical signal information such as the single cell voltage, current, temperature, state of charge (SOC) of all cells in each power battery, among which the power battery voltage (the single cell voltage of all cells) collected during the charging process includes at least terminal voltage, ohmic polarization, concentration polarization / electrochemical polarization, etc. When charging is completed and the current is removed, the power battery needs a certain amount of time to remove the polarization effect (i.e. depolarization) and then restore to the terminal voltage corresponding to the corresponding state of charge (SOC). The length of this process, i.e. the certain depolarization time (hereinafter referred to as: depolarization time t_polarization), is related to different battery design, structure, charging current and other factors. Figure 2 The following is a schematic diagram of voltage change curves for different power batteries after charging, according to one embodiment of a solution of the present invention: the vertical axis represents the single cell voltage of the power battery (hereinafter referred to as the cell voltage), and the horizontal axis represents the self-discharge monitoring time of an unused power battery. Time t0 is assumed to be the initial time, at which charging stops. After a period of time, time t1 is assumed to be the start time of the first stage, at which the depolarization process is completed. That is, depolarization is completed after the time t1-t0. It is possible to set t1>t0+t_polarization. For example, charging tests are first conducted on batteries of various types / specifications. Based on the test results, the depolarization time "t_polarization" corresponding to each type / specification of battery is accumulated. Then, in actual application, the corresponding t_polarization is directly retrieved based on the battery type / specification, and t1 is set according to the principle of "t1>t0+t_polarization". Since these self-discharge electrical signal information of the power battery have been collected in real time and uploaded synchronously to the cloud for storage, the cloud server can perform multi-stage and step-by-step observation and calculation on each corresponding power battery to ensure accurate calculation while taking into account the operating efficiency of the battery swap station (that is, power batteries without a high risk of internal short circuit can be directly provided to electric vehicles).

[0200] First, perform the first stage of self-discharge observation and calculation. After the power battery completes depolarization, the voltage of the power battery is basically stable, and there is basically no change in a short period of time, such as 7 days. Figure 2Type 1 shown; once a serious internal short circuit occurs, the voltage will drop rapidly, see Figure 2 Type 3 shown. Calculating the self-discharge rate of the power battery can be determined by observing the self-discharge of any cell in the power battery, that is, the change of the cell voltage over time.

[0201] In one embodiment, the principle of observation and calculation is as follows: the short circuit situation in the power battery can be evaluated by calculating the voltage change process after time t1; assuming that the voltage of cell j of power battery 1 is v_1j at time t1, and after a period of time after time t1, for example, at time ti, the power battery is in the first stage of self-discharge observation for a period of time P1_time, and the voltage of cell j at time ti is vi_ij; to calculate the self-discharge rate of the power battery, it can be observed that a certain cell, for example, cell j, reaches time ti after a period of time from time t1, and the cell t If i-t1 is within the time length P1_time of the first stage observation and calculation of self-discharge, calculation and observation are performed based on the voltage change of the j battery cell; wherein, i represents the i-th cell and is a natural number greater than 1; j represents the j-th cell and is a natural number greater than or equal to 1, and the value range of P1_time can be 1 to 24 hours, for example, it can be set to P1_time = 2 hours, P1_time = 1 hour, and so on as needed; specifically, the first stage self-discharge rate p1Sdr is calculated according to the above observation and calculation principles, as shown in Formula 1:

[0202]

[0203] Among them, v i,j is the cell voltage of cell j at time ti, v 1,j is the cell voltage of cell j at time t1, t i,j is the time of cell j, t 1,j is the time t1 of cell j. Here, the time length of ti-t1 is within P1_time, ti<t1+P1_time. Furthermore, the result of formula 1 of this observation and calculation principle needs to be taken in absolute value, such as Figure 2 As shown, the observed voltage change curve is decreasing, and the voltage at the next moment is often lower than that at the previous moment. Therefore, the calculated self-discharge rate p1Sdr can be analyzed and observed. More specifically, the staged and step-by-step observation and calculation of the battery self-discharge rate p1Sdr can be carried out in the following specific ways:

[0204] a) If ti < t1 + P1_time, then the first stage can be observed and calculated from t1 to ti. The self-discharge rate p1Sdr of the first stage can be obtained by formula 2:

[0205]

[0206] Here, ti < t1 + P1_time, where ti represents the time point at which the voltage self-discharge was observed in the first phase, and the time period from t1 to ti falls within the first phase self-discharge observation and calculation time P1_time, that is, is shorter than the duration of the first phase. Thus, the voltage from t1 to t1 + P1_time can be selected for analysis.

[0207] in, It is expressed as a time point t_i (moment) selected during the period from t1 to t1+P1_time, at which the voltage of cell j is observed. The corresponding voltage of cell j at this time is Indicates that the voltage of cell j is observed earlier than the selected time between t1 and t1+P1_time. As the starting time point t1 (moment), the corresponding cell voltage of j cell is

[0208] Furthermore, if the calculated p1Sdr>s1 (first threshold), it is judged that there is a relatively serious slight internal short circuit in the j cell, and thus the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, which triggers the interception of the power battery and continues to enter the second stage of self-discharge observation and calculation. If the calculated p1Sdr is not greater than the first threshold s1, for example: p1Sdr≤s1, it is judged that there is no slight internal short circuit in the j cell, and the internal short circuit risk of the power battery where the j cell is located is low, which is within the normal range and can be circulated normally. If an electric vehicle needs it, it can be replaced and used. Among them, the value range of s1 can be 0.1~100.

[0209] Furthermore, the cloud can complete the observation and calculation and then feed back the results (including normal situations and situations left for further observation in the next stage) to each battery swap station.

[0210] b) If ti>t1+P1_time, the self-discharge rate p1Sdr within the time length P1_time is calculated using a sliding window. For example, the cell voltage from ti to ti+P1_time is extracted for observation and calculation. The self-discharge rate p1Sdr in the first stage is calculated as shown in Formula 3:

[0211]

[0212] Here, ti>t1+P1_time, ti represents the time point when the voltage self-discharge is observed in the first stage, and the time period from t1 observation to ti exceeds the first stage self-discharge observation and calculation time P1_time, that is, it is longer than the time of the first stage. In this way, we can skip the moment t1 and select the voltage from the moment ti to the period of ti+P1_time for analysis.

[0213] in, It represents a time point ti (moment) selected during the period from ti to ti+P1_time when the voltage of cell j is observed. The corresponding voltage of cell j at this time is Indicates that the voltage of cell j is observed earlier than the selected time from ti to ti+P1_time A certain time point t as the starting point i -P1_time (time), the corresponding cell voltage of cell j is

[0214] Furthermore, if the calculated p1Sdr>s1 (first threshold), it is judged that there is a relatively serious slight internal short circuit in the j cell, and thus the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, which triggers the interception of the power battery and continues to enter the second stage of self-discharge observation and calculation. If the calculated p1Sdr is not greater than the first threshold s1, for example: p1Sdr≤s1, it is judged that there is no slight internal short circuit in the j cell, and the internal short circuit risk of the power battery where the j cell is located is low and falls within the normal range. It can be circulated normally and replaced for use when an electric vehicle needs it. Among them, the value range of s1 can be 0.1~100.

[0215] Furthermore, the cloud can complete the observation and calculation and then feed back the results (including normal situations and situations left for further observation in the next stage) to each battery swap station.

[0216] In b), the sliding window calculation method can accurately calculate the trend change of the monotonically changing curve, save cloud computing resources, and improve computing efficiency.

[0217] Second, the second phase of self-discharge observation and calculation is performed. This second phase, with a longer observation and calculation period (P2_time), focuses on power batteries identified in the first phase as having a high risk of internal short circuits. The self-discharge rate (p2Sdr) is observed and calculated similarly to the first phase.

[0218] For example, the time length P2_time can be set to n times of P1_time, and the value of the multiple n is between 2 and 10. During this stage, the second stage self-discharge rate p2Sdr can be observed and calculated, as shown in Formula 4:

[0219]

[0220] Among them, t i+P2_time,j It is expressed as a time point t selected from the moment ti when the second stage starts to ti+P2_time, at which the voltage of cell j is observed. i+P2_time At this moment, the corresponding voltage of cell j is v i+P2_time,j ;t i,j Indicates that the voltage of cell j is observed earlier than t during the period from ti to ti+P2_time. i+P2_time A certain time point t as the starting point i At this moment, the cell voltage of the corresponding j cell is v i,j .

[0221] Furthermore, if the calculated p2Sdr>s2 (second threshold), it is judged that there is a relatively serious slight internal short circuit in the j cell, and thus the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, and it is determined to trigger an alarm for the power battery, stop using it, and start the return repair process and other subsequent processing. If the calculated p2Sdr is not greater than the second threshold s2, for example: p2Sdr≤s2, it is judged that there is no slight internal short circuit in the j cell, and the internal short circuit risk of the power battery where the j cell is located is low, which is within the normal range and can be circulated normally. If an electric vehicle needs it, it can be replaced and used. Among them, the value range of s2 can be 0.1~100.

[0222] Among them, it can be preset that s1>s2>battery cell self-discharge specification.

[0223] Furthermore, a linear fitting method can be used to calculate the self-discharge rate (SDR) of a power battery to replace the calculation method in each stage. That is, the linear fitting method is used for both the first and second stage calculations. For example, the linear fitting method performs a linear fitting calculation on the voltage of all j cells within a certain time range of a power battery, and uses the slope as the self-discharge rate (SDR), that is, SDR = k. The linear fitting formula is as shown in Formula 5:

[0224] v^=v0+kt i Formula 5

[0225] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t iThe end time of this period.

[0226] Similarly, the result of k, that is, the self-discharge rate sdr, can be compared with s1 and s2 (sdr1 and sdr2). For example: in the first stage, if the calculated self-discharge rate sdr1>s1, the observation will be continued in the second stage; if the calculated sdr2>s2 in the second stage, an alarm and other subsequent processing will be triggered, otherwise it means that the power battery is normal; and if sdr1 is not greater than s1 in the first stage, it means that the power battery is normal, that is, the method of comparison, judgment, observation and analysis is the same as that described in the first and second stages above, except that the calculation method of the self-discharge rates sdr1 and sdr2 in each stage is relatively simple and the accuracy is relatively low.

[0227] Furthermore, the cloud can complete the observation and calculation and then feed back the results to each battery swap station. Figure 1 As shown, after the cloud server completes the calculation, it feeds back the results to each battery swap station, triggering subsequent processing of one or more power batteries in the corresponding battery swap station: alarm, stop using and start the return and repair process, etc.

[0228] See attached Figure 3 , Figure 3 1 is a flow chart of the main steps of an embodiment of a method for monitoring battery short circuit according to the present invention. This embodiment includes at least the following steps:

[0229] Step S310: receiving collected electrical signal information of all cells in each power battery.

[0230] In one embodiment, the power battery is stationary in the battery swap station, and the battery swap station charges each power battery stored in the battery swap station, and after charging is completed, the power batteries are stationary in the battery swap station before being provided to the electric vehicle. During the charging process and after the charging is ended / after the charging is completed, the battery swap station can collect electrical signal information of each power battery stationary in the battery swap station through a data collection device. Specifically, in the battery swap station, a computer with a sensor for collecting data can monitor the status of each power battery; during the charging process and in the stationary state after charging is completed, the electrical signal information such as the single cell voltage, current, temperature, state of charge (SOC) of all the cells of each power battery are collected in real time, and then uploaded in real time to synchronize with the cloud connected to the battery swap station, and received and stored by the storage device on the cloud. As an example, the storage of electrical signal information can be stored corresponding to the collection time of each cell in each power battery.

[0231] In this way, the monitoring of slight internal short circuits in power batteries requires the most accurate data acquisition, and the most accurate data acquisition can be determined by monitoring the rate of battery voltage reduction when the power battery is stationary for a period of time, thereby determining the situation of internal short circuits in the battery. Based on the stationary scenario of the battery swap station, the power battery has no additional electrical interference, can be stored for a long time, and can provide continuous real-time monitoring conditions. Then, the electrical signal information of the power battery can be accurately obtained, which will help the subsequent staged algorithm design of self-discharge observation and self-discharge rate calculation data to be more sufficient and accurate, improve the accuracy of self-discharge rate calculation, and then accurately determine the situation of internal short circuits in the power battery. In addition, in the past, calculating the self-discharge rate of the power battery required removing the battery from the vehicle, which was costly. For the circulating battery system using the battery swap station system, the cost is greatly reduced by monitoring the data of the battery during the battery swap and storage, and then performing the calculation.

[0232] Step S320 , performing self-discharge observation and calculating the self-discharge rate based on the cell voltage in the electrical signal information of each cell in the power battery after depolarization is completed, to determine whether the power battery corresponding to the cell has an internal short circuit.

[0233] In one implementation, a phased calculation approach is designed, leveraging the cloud to store massive amounts of long-term data on power batteries. This data can be used to accurately calculate the battery's self-discharge rate, enabling subsequent battery status assessments, such as whether it is short-circuited. Furthermore, during the calculation process, an improved algorithm is employed. Using a multi-stage, step-by-step approach, such as the two described above, this approach balances calculation accuracy with station operational efficiency. Batteries that do not exceed the threshold in the first stage can be directly put into operation and supplied to electric vehicles in need.

[0234] In one embodiment, see Figure 4 FIG. 1 is a flow chart showing the main steps of an embodiment of a process for calculating the self-discharge rate according to a method of the present invention.

[0235] Step S3201 : determining the time for stopping charging of the power battery in which the battery cell is located based on the acquisition time of the electrical signal information corresponding to each battery cell.

[0236] In one example, the electrical signal information of each battery cell is uploaded and synchronized to the cloud for corresponding storage according to the real-time collection time. That is, finding the electrical signal information of each battery cell can also find the corresponding collection time. Furthermore, in another example, the time point when the current of all battery cells (i.e., corresponding power batteries) is zero can be found from the electrical signal information in the order of collection time, which is used as the time t0 when the battery stops charging.

[0237] Step S3202 : selecting a starting time for starting first-stage self-discharge observation and calculation of the cell voltage in the electrical signal information corresponding to each cell in the power battery according to the time when the power battery stops charging and the depolarization time corresponding to the type of the power battery.

[0238] Specifically, the time for the power battery to be depolarized can be set based on the time when the power battery stops charging and the depolarization time (t_polarization) corresponding to the type of the power battery. In one embodiment, during the charging process of the power battery, in addition to the terminal voltage, the voltage of the battery cell may also have ohmic polarization, concentration polarization / electrochemical polarization, etc. Once the charging is completed and the current is removed, the battery needs a certain amount of time to remove the polarization effect. Therefore, the power battery needs depolarization time after charging is completed. The length of this time t_polarization is related to different battery designs, structures, charging currents and other factors, see Figure 2 In the voltage curve shown, charging stops at t0 and the depolarization process is complete at t1. Generally, t1 > t0 + t_polarization, indicating complete depolarization. For example, for power batteries of different types or specifications, charging tests can be performed on various types / specifications of power batteries. Based on the test results, the corresponding depolarization time, or depolarization duration t_polarization, can be accumulated for each type / specification of power battery. This can be recorded as a fixed parameter for the corresponding type / specification of power battery. In other words, knowing the type / specification of the power battery (such as the model code) can determine the corresponding depolarization time t_polarization. Then, based on the principle of t1 > t0 + t_polarization and actual requirements, combined with the already determined t0, the minimum depolarization time after complete depolarization is determined to be t0 + t_polarization. This allows selection of the appropriate acquisition time for each cell's electrical signal information as the start time t1 for the first stage of self-discharge observation and calculation. For example: the depolarization time t_polarization of a power battery i of model R at battery swap station 1 is 2 hours, and t0 is 14:00 on January 2, 2020. Then a time after 16:00 can be determined, for example, t1 is 16:30 on January 2, 2020. This time point can be used as the time for starting the first stage of self-discharge observation and calculation after the depolarization of the power battery i is completed, which means that at 4:30 in the afternoon of that day, the depolarization of the power battery i of model R at the battery swap station has been completed. This time is the starting time for starting the first stage of self-discharge observation and calculation of the power battery i.

[0239] Step S3203: Starting from the selected start time of the first-stage self-discharge observation and calculation, the first-stage self-discharge observation and calculation are performed on the cell voltage in the electrical signal information of each cell in each power battery to obtain the first-stage self-discharge rate (p1Sdr) of each cell to determine whether the power battery where the cell is located performs the second-stage self-discharge observation and calculation.

[0240] In one embodiment, the cloud stores a large amount of electrical signal information of all cells of a power battery uploaded from a certain battery swap station. The electrical signal information of each cell at least includes the corresponding cell voltage of the cell at a certain time point / moment. After the depolarization of the power battery is completed, the voltage of the power battery is in a basically stable state and will not change in a short period of time, such as 7 days. Figure 2 As shown in Type 1, if an internal short circuit occurs, the voltage will drop rapidly, as shown in Figure 2 As shown in Type 3, the short circuit situation in the battery can be evaluated by calculating the voltage change process after the first stage self-discharge observation selected after the polarization is completed and the calculated starting time t1.

[0241] The principle of observation and calculation is as follows: the short circuit situation in the power battery can be evaluated by calculating the voltage change process after time t1; assuming that the voltage of cell j of power battery 1 is v_1j at time t1, and after a period of time after time t1, for example, at time ti, the power battery is in the first stage of self-discharge observation, the time length P1_time, and the voltage of cell j at time ti is vi_ij; to calculate the self-discharge rate of the power battery, it can be done by observing a cell, for example, cell j, after a period of time from time t1 to time ti, and the ti- If t1 is within the first stage observation and calculation time length P1_time, calculation and observation are performed based on the voltage change of the j battery cell; wherein, i represents the i-th cell and is a natural number greater than 1; j represents the j-th cell and is a natural number greater than or equal to 1, and the value range of P1_time can be 1 to 24 hours, for example, it can be set to P1_time = 2 hours, P1_time = 1 hour, and so on as needed; specifically, the first stage self-discharge rate p1Sdr is calculated according to the above observation and calculation principles, as shown in Formula 1:

[0242]

[0243] Among them, v i,j is the cell voltage of cell j at time ti, v 1,j is the cell voltage of cell j at time t1, t i,j is the time of cell j, t 1,jis the time t1 of cell j. Here, the time length of ti-t1 is within P1_time, ti<t1+P1_time. Furthermore, the result of formula 1 of this observation and calculation principle is the result of taking the absolute value, such as Figure 2 As shown in the figure, the observed voltage change curve is decreasing, and the voltage at the next moment is often lower than that at the previous moment. Therefore, the calculated self-discharge rate p1Sdr can be analyzed and observed.

[0244] Based on the above principle, in one embodiment: from t1 to ti, the calculation is performed according to the following situations

[0245] a) If ti < t1 + P1_time, then the first stage can be observed and calculated from t1 to ti. The self-discharge rate p1Sdr of the first stage can be obtained by formula 2:

[0246]

[0247] Here, ti < t1 + P1_time, where ti represents the time point at which the voltage self-discharge was observed in the first phase, and the time period from t1 to ti is within the self-discharge observation and calculation time length P1_time in the first phase, that is, shorter than the duration of the first phase. In this way, the voltage from t1 to t1 + P1_time can be selected for analysis.

[0248] in, It is expressed as a time point ti (moment) selected during the period from t1 to t1+P1_time when the voltage of cell j is observed. The corresponding voltage of cell j at this time is Indicates that the voltage of cell j is observed earlier than the selected time from t1 to t1+P1time As the starting time point t_1 (moment), the corresponding cell voltage of j cell is

[0249] Example 1: P1_time = 1 hour, t_polarization = 2 hours, the charging end time of a power battery is t0 = 13:00, the start time of the first stage t1 (cycle 1) is selected, t1 = 16:00, t1-t0>2, which means that the selected t1 is after the depolarization is completed. If ti < t1+1, such as ti = 16:30, the cell voltage of each cell of the power battery during the period from t1 to t1+1 can be extracted for analysis. For example, the cell voltage corresponding to each time point of any cell j during the period from 16:00 to 17:00 can be analyzed. For example: t t_i,j =16:50, tt_1,j =16:00, and the cell voltage v corresponding to 16:50 t_i,j =1, cell voltage v at 16:00 t_1,j =1.01, p1Sdr=0.012.

[0250] Furthermore, if the calculated p1Sdr>s1 (first threshold), it is judged that there is a relatively serious slight internal short circuit in the j cell, and thus the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, which triggers the interception of the power battery and continues to enter the second stage of self-discharge observation and calculation. If the calculated p1Sdr is not greater than the first threshold s1, for example: p1Sdr≤s1, it is judged that there is no slight internal short circuit in the j cell, and the internal short circuit risk of the power battery where the j cell is located is low, which is within the normal range and can be circulated normally. If an electric vehicle needs it, it can be replaced and used. Among them, the value range of s1 can be 0.1~100. Continuing with Example 1: if p1Sdr is 0.012 and s1 is 0.2, then 0.012 < s1, and the battery will flow normally. If p1Sdr is 0.3, then 0.3 > s1, and cycle 2 will be triggered. That is to say, if the cell voltages of all the cells in a certain power battery do not have the situation of p1Sdr > s1 in the first stage of self-discharge observation and calculation (cycle 1), the second stage of self-discharge observation and calculation will not be triggered. Otherwise, if the cell voltage of any cell in a certain power battery has the situation of p1Sdr > s1 in cycle 1, it is considered that the power battery may have a slight internal short circuit, which is a greater risk, and the second stage of self-discharge observation and calculation (cycle 2) will be triggered.

[0251] Furthermore, the cloud can complete the observation and calculation and then feed back the results (including normal situations and situations left for further observation in the next stage) to each battery swap station.

[0252] b) If ti>t1+P1_time, the self-discharge rate p1Sdr within the time length P1_time is calculated using a sliding window. For example, the cell voltage from ti to ti+P1_time is extracted for observation and calculation. The self-discharge rate p1Sdr in the first stage is calculated as shown in Formula 3:

[0253]

[0254] Here, ti>t1+P1_time, ti represents the time point when the voltage self-discharge is observed in the first stage, and the time period from t1 observation to ti exceeds the first stage self-discharge observation and calculation time P1_time, that is, it is longer than the time of the first stage. In this way, we can skip the moment t1 and select the voltage from the moment ti to the period of ti+P1_time for analysis.

[0255] in, It represents a time point t_i (moment) selected during the period from ti to ti+P1_time when the voltage of cell j is observed. The corresponding voltage of cell j at this time is Indicates that the voltage of cell j is observed earlier than the selected time from ti to ti+P1_time A certain time point t as the starting point i -P1_time (time), the corresponding cell voltage of cell j is

[0256] Example 2: P1_time = 1 hour, t_polarization = 2 hours, the charging end time of a power battery is t0 = 13:00, the start time of the first stage t1 (cycle 1) is selected, t1 = 16:00, t1-t0>2, which means that the selected t1 is after the depolarization is completed. If ti> t1+1, such as ti = 17:10, the cell voltage of each cell of the power battery corresponding to the period from ti to ti+1 can be extracted for analysis. For example, the cell voltage corresponding to each time point of any cell j of the power battery during the period from 17:30 to 18:30 can be analyzed. For example: t t_i,j =18:30, And the cell voltage v corresponding to 18:30 t_i,j =1, cell voltage at 17:40 p1Sdr=0.36.

[0257] Furthermore, if the calculated p1Sdr>s1 (first threshold), it is judged that there is a relatively serious slight internal short circuit in the j cell, and thus the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, which triggers the interception of the power battery and continues to enter the second stage of self-discharge observation and calculation. If the calculated p1Sdr is not greater than the first threshold s1, for example: p1Sdr≤s1, it is judged that there is no slight internal short circuit in the j cell, and the internal short circuit risk of the power battery where the j cell is located is low and falls within the normal range. It can be circulated normally and replaced for use when an electric vehicle needs it. Among them, the value range of s1 can be 0.1~100. Continuing with Example 2: if p1Sdr is 0.36 and s1 is 0.2, then 0.36>s1, and cycle 2 is triggered. If p1Sdr is 0.1, then 0.1<s1, and the process flows normally. That is to say, if the cell voltages of all cells in a certain power battery do not have the situation of p1Sdr>s1 in the first stage of self-discharge observation and calculation (cycle 1), the second stage of self-discharge observation and calculation will not be triggered. Otherwise, if the cell voltage of any cell in a certain power battery has the situation of p1Sdr>s1 in cycle 1, it is considered that the power battery may have a slight internal short circuit, which is a greater risk, and the second stage of self-discharge observation and calculation (cycle 2) is triggered.

[0258] Furthermore, the cloud can complete the observation and calculation and then feed back the results (including normal situations and situations left for further observation in the next stage) to each battery swap station.

[0259] In b), the sliding window calculation method can accurately calculate the trend change of the monotonically changing curve, save cloud computing resources, and improve computing efficiency.

[0260] Furthermore, a linear fitting method can be used to calculate the self-discharge rate (SDR) of a power battery to replace the calculation method in each stage. That is, the calculation of cycle 1 uses this linear fitting method. For example: using the linear fitting method, a linear fitting calculation is performed on the cell voltage of any j cell among all the cells of a power battery within a certain time range, and the slope is used as the self-discharge rate (SDR1), that is, SDR = k. The linear fitting formula is as shown in Formula 5:

[0261] v^=v0+kt i Formula 5

[0262] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i The end time of this period.

[0263] Similarly, the result of k, that is, the self-discharge rate sdr1, can be compared with s1. For example: in cycle 1, if the self-discharge rate sdr1 is calculated to be greater than s1, then the observation is continued in the second stage, that is, cycle 2. Otherwise, if there is no voltage change of the battery cell, that is, the self-discharge rate sdr1 is greater than s1, then the power battery is operating normally.

[0264] Step S3204: When it is determined that the power battery where the battery cell is located is performing the second stage self-discharge observation and calculation, the second stage self-discharge observation and calculation of the cell voltage of each battery cell of the power battery is performed for a time length (P2_time) greater than the first stage self-discharge observation and calculation, and the time after the end of the first stage self-discharge observation and calculation is selected to obtain the second stage self-discharge rate (p2Sdr) of each battery cell to determine whether the power battery where the battery cell is located has an internal short circuit.

[0265] Specifically, the second phase of self-discharge observation and calculation (cycle 2) is for the power battery that is judged to have a high risk of internal short circuit in cycle 1. The start time of the second phase is after the first phase of the power battery in which the battery cell is located is completed, and a certain time is selected as the starting time point, such as Figure 2 As shown, t2, t3, etc., and the way of observing and calculating the self-discharge in the second stage to obtain the self-discharge rate p2Sdr is similar to that in the first stage.

[0266] For example, the time length P2_time can be set to n times of P1_time, and the value of the multiple n is between 2 and 10. During this stage, the second stage self-discharge rate p2Sdr can be observed and calculated, as shown in Formula 4:

[0267]

[0268] Among them, t i+P2_time,j It is expressed as a time point t selected from a certain moment ti after the start of the second stage to ti+P2_time during which the voltage of cell j is observed. i+P2_time At this moment, the corresponding voltage of cell j is v i+P2_time,j ;t i,j It is expressed as the time from a certain moment ti after the start of the second stage to ti+P2_time during which the voltage of cell j is observed earlier than t i+P2_time A certain time point t as the starting point i At this moment, the cell voltage of the corresponding j cell is v i,j For examples, see the calculations in Examples 1 and 2 in a) and b) above.

[0269] Furthermore, if the calculated p2Sdr>s2 (second threshold), it is judged that the j cell has a relatively serious slight internal short circuit, so that the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, and the alarm for the power battery is triggered, the use is stopped, and the return repair process and other subsequent processing are initiated. If the calculated p2Sdr is not greater than the second threshold s2, for example: p2Sdr≤s2, it is judged that the j cell does not have a slight internal short circuit. When all the cells of the power battery where the j cell is located do not have the situation of p2Sdr>s2, it indicates that the internal short circuit risk of the power battery is low and belongs to the normal range. It can be circulated normally and can be replaced and used when an electric vehicle needs it. Among them, the value range of s2 can be 0.1~100.

[0270] Among them, it can be preset that s1>s2>battery cell self-discharge specification.

[0271] Furthermore, the self-discharge rate in the second stage can also be calculated using a linear fitting method to calculate the self-discharge rate sdr2 of a power battery, replacing the calculation method in each stage. That is, the calculation in the second stage uses this linear fitting method. For example: the linear fitting method performs a linear fitting calculation on the voltage of all j cells in a certain time range of a power battery, and uses the slope as the self-discharge rate sdr2, that is, sdr2 = k. The linear fitting formula is as shown in Formula 5:

[0272] v^=v0+kt i Formula 5

[0273] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i The end time of this period.

[0274] Similarly, the result of k, that is, the self-discharge rate sdr2, can be compared with s2. For example, if sdr2>s2 is calculated in the second stage, an alarm and other subsequent processing are triggered. Otherwise, it indicates that the power battery is normal.

[0275] Through phased design and sliding window design and calculation, the consumption of computing and operating resources is reduced. At the same time, the self-discharge calculation is divided into a shorter observation cycle 1 and a longer observation cycle 2. The changes in the situation in cycle 1 trigger the observation of cycle 2, intercepting a small number of high-risk power batteries. This ensures calculation accuracy while not affecting the battery circulation operation of the entire battery swap station, thus achieving a balanced operation.

[0276] Step S330 : triggering safety processing of the power battery according to determining that the power battery where the battery cell is located has an internal short circuit.

[0277] For example, the cloud can complete observation and calculation and then feed back the results to each battery swap station. Figure 1 As shown, after the cloud server completes the calculation, it feeds back the results to each battery swap station, thereby triggering the subsequent processing of one or more power batteries in the corresponding battery swap station, that is, the safety processing of the power battery: alarm, suspension of use, and initiation of return and repair procedures, etc. The alarm can output an alarm message or provide various warning signals such as sound, light and / or electricity.

[0278] In another embodiment, the present invention can transplant the internal short-circuit monitoring calculation of the power battery in the cloud to the internal software of the local control device of each battery swap station for execution.

[0279] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not have to be performed in such an order. They can be performed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present invention.

[0280] The following combination Figure 5 The present invention is further described in detail with reference to a flowchart of an example of application software control of the method for monitoring battery short circuits according to the present invention.

[0281] Step 1: In a stationary power battery environment, such as a battery swap station, collect signal information such as single-cell voltage, current, temperature, and charge for all cells in each stored power battery, including information during charging and the rest period after charging. This information is then uploaded and synchronized in real time to the cloud or the local battery swap station control device for storage and subsequent calculations. The cloud or, in another embodiment, the battery swap station control software has computing and data storage capabilities.

[0282] Step 2: The cloud or local end performs monitoring calculations based on the real-time information uploaded synchronously. Specifically, the time t0 at which a certain power battery is charged (stopped charging) is determined. This can be determined by determining whether charging is completed at a certain time, that is, whether this time is set as t0.

[0283] In step 3, if the power battery is stationary at a battery swap station and unused, it undergoes depolarization after t0. The time after t0 is monitored. When time t1 is detected, a determination is made as to whether t1-t0 is greater than the depolarization duration, t_polarization. If so, the process proceeds to step 4, the first stage of self-discharge observation and calculation. Otherwise, the depolarization process is completed and the depolarization completion time, t1, is determined. Monitoring can be performed by the cloud or a local control device.

[0284] Step 4, enter the first stage of self-discharge observation and calculation (cycle 1), for example Figure 2 As shown, from t1 to t2, the change in cell voltage of one or more cells in a power battery during cycle 1 is calculated, i.e., the self-discharge rate p1Sdr. This is calculated by a cloud server or a local control device processing device.

[0285] Step 5: Determine whether p1Sdr / sdr1 is greater than the first threshold s1. If so, a slight internal short circuit may exist. Therefore, the power battery containing the cell with the corresponding self-discharge rate needs to be retained for the next stage of self-discharge observation and calculation, proceeding to step 6. If not, the cell with the corresponding self-discharge rate is considered to have no slight internal short circuit. Therefore, when all cells in a power battery have no slight internal short circuit, the power battery is normal and can be transferred. The cloud or local control device feeds back the calculation and judgment results to the battery swap station.

[0286] Step 6: After the first phase of observation and calculation, the power battery where the self-discharge rate is greater than s1 is determined to be located is subjected to the second phase of observation and calculation (cycle 2), for example Figure 2 As shown, from t2 to t3, cycle 2 is longer than cycle 1, for example, n times longer than cycle 1. Similarly, after completion, the change in cell voltage of one or more cells in the power battery during cycle 2, i.e., the self-discharge rate p2Sdr / sdr2, is calculated. This is monitored and calculated by a cloud server or a local control device processing unit.

[0287] Step 7: Determine whether p2Sdr is greater than a second threshold value s2. If it is greater, it is considered that there may be a slight internal short circuit. Therefore, the power battery containing the cell with the corresponding self-discharge rate needs to be alerted (such as step 8: providing alarm information) and other subsequent processing related to battery safety. If it is not greater, it is considered that the cell with the corresponding self-discharge rate has no slight internal short circuit. Therefore, when all cells in a power battery have no slight internal short circuit, it indicates that the power battery is normal and can be circulated. The cloud or local control device will feedback the calculation and judgment results to the battery swap station.

[0288] Step 8: Perform safety measures, such as issuing an alarm, on power batteries identified as having internal short circuits after real-time monitoring. After receiving feedback, the battery swap station triggers various measures, such as safety measures (alarms), on the corresponding power batteries. If the battery swap station receives feedback from steps 5 and 7 indicating no internal short circuits, the power battery can continue to operate normally.

[0289] Among them, s1>s2>battery cell self-discharge specification, and the first threshold s1 and the second threshold s2 are in the range of 0.1 to 100.

[0290] refer to Figure 6 , Figure 6 1 is a schematic diagram of the main structure of an embodiment of a system for monitoring battery short circuits according to the present invention. The system at least includes:

[0291] The receiving storage device 610 is used to receive the collected electrical signal information of all cells in each power battery. In one embodiment, the power battery is stationary at the battery swap station, and the battery swap station charges each power battery stored in the battery swap station, and after charging is completed, the power battery is stationary at the battery swap station before being provided to the electric vehicle. During the charging process and after the charging is ended / after the charging is completed, the battery swap station can collect electrical signal information of each power battery stationary in the battery swap station through a data collection device. Specifically, in the battery swap station, a computer with a sensor for collecting data can monitor the status of each power battery; during the charging process and in the stationary state after charging is completed, the electrical signal information such as the single cell voltage, current, temperature, state of charge (SOC) of all cells of each power battery is collected in real time, and then uploaded in real time to synchronize with the cloud connected to the battery swap station, and received and stored by the storage device on the cloud. As an example, the storage of electrical signal information can be stored corresponding to the collection time of each cell in each power battery. In this way, the monitoring of slight internal short circuits in power batteries requires the most accurate data acquisition, and the most accurate data acquisition can be determined by monitoring the rate of battery voltage reduction when the power battery is stationary for a period of time, thereby determining the situation of internal short circuits in the battery. Based on the stationary scenario of the battery swap station, the power battery has no additional electrical interference, can be stored for a long time, and can provide continuous real-time monitoring conditions. Then, the electrical signal information of the power battery can be accurately obtained, which will help the subsequent staged algorithm design of self-discharge observation and self-discharge rate calculation data to be more sufficient and accurate, improve the accuracy of self-discharge rate calculation, and then accurately determine the situation of internal short circuits in the power battery. In addition, in the past, calculating the self-discharge rate of the power battery required removing the battery from the vehicle, which was costly. For the circulating battery system using the battery swap station system, the cost is greatly reduced by monitoring the data of the battery during the battery swap and storage, and then performing the calculation.

[0292] The staged calculation device 620 is used to observe the self-discharge and calculate the self-discharge rate according to the cell voltage in the electrical signal information of each cell in the power battery after each depolarization is completed, so as to determine whether there is an internal short circuit in the power battery where the cell is located.

[0293] The device is designed with a phased calculation method. It uses the cloud to store large amounts of data on power batteries over long periods of time. This data can be used to accurately calculate the battery self-discharge rate, and then to determine the battery status, such as whether it is short-circuited. In addition, during the calculation process, the algorithm has been improved. Through a multi-stage and step-by-step approach, such as the two stages mentioned above, it can not only take into account the accuracy of the calculation, but also ensure the operational efficiency of the battery swap station. In other words, batteries that do not exceed the threshold in the first stage can directly enter operation and be provided to electric vehicles in need of batteries.

[0294] In one embodiment, the staged computing device 620 further includes:

[0295] The charging stop time device 6201 is used to determine the time when the power battery containing each cell stops charging based on the collection time of the electrical signal information corresponding to each cell. In one example, the electrical signal information of each cell is uploaded and synchronized to the cloud for corresponding storage according to the real-time collection time. That is, by finding the electrical signal information of each cell, the corresponding collection time can be found. Furthermore, in one example, the time point when the current of all cells (i.e., the corresponding power batteries) is zero can be found from the electrical signal information in the order of collection time, which is used as the time t0 when the battery stops charging.

[0296] The first stage starting device 6202 is selected to select the starting time for starting the first stage of self-discharge observation and calculation of the cell voltage in the corresponding electrical signal information of each cell in the power battery according to the time when the power battery stops charging and the depolarization time corresponding to the type of the power battery. Specifically, the time for the depolarization of the power battery to be completed can be set according to the time when the power battery stops charging and the depolarization time (t_polarization) corresponding to the type of the power battery. In one embodiment, since the voltage of the cell may have ohmic polarization, concentration polarization / electrochemical polarization in addition to the terminal voltage during the charging process of the power battery, once the charging is completed and the current is removed, the battery needs a certain amount of time to remove the polarization effect. Therefore, the power battery needs depolarization time after charging is completed. The length of this time t_polarization is related to different battery designs, structures, charging currents and other factors, see Figure 2In the voltage curve shown, charging stops at t0 and the depolarization process is complete at t1. Generally, t1 > t0 + t_polarization, indicating complete depolarization. For example, for power batteries of different types or specifications, charging tests can be performed on various types / specifications of power batteries. Based on the test results, the corresponding depolarization time, or depolarization duration t_polarization, can be accumulated for each type / specification of power battery. This can be recorded as a fixed parameter for the corresponding type / specification of power battery. In other words, knowing the type / specification of the power battery (such as the model code) can determine the corresponding depolarization time t_polarization. Then, based on the principle of t1 > t0 + t_polarization and actual requirements, combined with the already determined t0, the minimum depolarization time after complete depolarization is determined to be t0 + t_polarization. This allows selection of the appropriate acquisition time for each cell's electrical signal information as the start time t1 for the first stage of self-discharge observation and calculation. For example: the depolarization time t_polarization of a power battery i of model R at battery swap station 1 is 2 hours, and t0 is 14:00 on January 2, 2020. Then a time after 16:00 can be determined, for example, t1 is 16:30 on January 2, 2020. This time point can be used as the time for starting the first stage of self-discharge observation and calculation after the depolarization of the power battery i is completed, which means that at 4:30 in the afternoon of that day, the depolarization of the power battery i of model R at the battery swap station has been completed. This time is the starting time for starting the first stage of self-discharge observation and calculation of the power battery i.

[0297] The first stage calculation device 6203 is used to perform the first stage self-discharge observation and calculation on the cell voltage in the electrical signal information of each cell in each power battery from the selected starting time of the first stage self-discharge observation and calculation, and obtain the first stage self-discharge rate (p1Sdr) of each cell to determine whether the power battery where the cell is located performs the second stage self-discharge observation and calculation. In one embodiment, the cloud stores a large amount of electrical signal information of all cells of a power battery uploaded by a certain battery swap station. The electrical signal information of each cell includes at least the corresponding cell voltage of the cell at a certain time point / moment. After the depolarization of the power battery is completed, the voltage of the power battery is in a basically stable state, and there will be basically no change in a short period of time, such as 7 days. Figure 2 As shown in Type 1, if an internal short circuit occurs, the voltage will drop rapidly, as shown in Figure 2 As shown in Type 3, the short circuit situation in the battery can be evaluated by calculating the voltage change process after the first stage self-discharge observation selected after the polarization is completed and the calculated starting time t1.

[0298] The principle of observation and calculation is as follows: the short circuit situation in the power battery can be evaluated by calculating the voltage change process after time t1; assuming that the voltage of cell j of power battery 1 is v_1j at time t1, and after a period of time after time t1, for example, at time ti, the power battery is in the first stage of self-discharge observation, the time length P1_time, and the voltage of cell j at time ti is vi_ij; to calculate the self-discharge rate of the power battery, it can be done by observing a cell, for example, cell j, after a period of time from time t1 to time ti, and the ti- If t1 is within the first stage observation and calculation time length P1_time, calculation and observation are performed based on the voltage change of the j battery cell; wherein, i represents the i-th cell and is a natural number greater than 1; j represents the j-th cell and is a natural number greater than or equal to 1, and the value range of P1_time can be 1 to 24 hours, for example, it can be set to P1_time = 2 hours, P1_time = 1 hour, and so on as needed; specifically, the first stage self-discharge rate p1Sdr is calculated according to the above observation and calculation principles, as shown in Formula 1:

[0299]

[0300] Among them, v i,j is the cell voltage of cell j at time ti, v 1,j is the cell voltage of cell j at time t1, t i,j is the time of cell j, t 1,j is the time t1 of cell j. Here, the time length of ti-t1 is within P1_time, ti<t1+P1_time. Further, the result of formula 1 of this observation and calculation principle can be taken as absolute value, such as Figure 2 As shown in the figure, the observed voltage change curve is decreasing, and the voltage at the next moment is often lower than that at the previous moment. Therefore, the calculated self-discharge rate p1Sdr can be analyzed and observed.

[0301] Based on the above principle, in one embodiment: from t1 to ti, the calculation is performed according to the following situations

[0302] a) If ti < t1 + P1_time, then the first stage can be observed and calculated from t1 to ti. The self-discharge rate p1Sdr of the first stage can be obtained by formula 2:

[0303]

[0304] Here, ti < t1 + P1_time, where ti represents the time point at which the voltage self-discharge was observed in the first phase, and the time period from t1 to ti is within the self-discharge observation and calculation time length P1_time in the first phase, that is, shorter than the duration of the first phase. In this way, the voltage from t1 to t1 + P1_time can be selected for analysis.

[0305] in, It is expressed as a time point ti (moment) selected during the period from t1 to t1+P1_time when the voltage of cell j is observed. The corresponding voltage of cell j at this time is Indicates that the voltage of cell j is observed earlier than the selected time between t1 and t1+P1_time. As the starting time point t1 (moment), the corresponding cell voltage of j cell is

[0306] Example 1: P1_time = 1 hour, t_polarization = 2 hours, the charging end time of a power battery is t0 = 13:00, the start time of the first stage t1 (cycle 1) is selected, t1 = 16:00, t1-t0>2, which means that the selected t1 is after the depolarization is completed. If ti < t1+1, such as ti = 16:30, the cell voltage of each cell of the power battery during the period from t1 to t1+1 can be extracted for analysis. For example, the cell voltage corresponding to each time point of any cell j during the period from 16:00 to 17:00 can be analyzed. For example: t t_i,j =16:50, t t_1,j =16:00, and the cell voltage v corresponding to 16:50 t_i,j =1, cell voltage v at 16:00 t_1,j =1.01, p1Sdr=0.012.

[0307] Furthermore, if the calculated p1Sdr>s1 (first threshold), it is judged that there is a relatively serious slight internal short circuit in the j cell, and thus the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, which triggers the interception of the power battery and continues to enter the second stage of self-discharge observation and calculation. If the calculated p1Sdr is not greater than the first threshold s1, for example: p1Sdr≤s1, it is judged that there is no slight internal short circuit in the j cell, and the internal short circuit risk of the power battery where the j cell is located is low, which is within the normal range and can be circulated normally. If an electric vehicle needs it, it can be replaced and used. Among them, the value range of s1 can be 0.1~100. Continuing with Example 1: if p1Sdr is 0.012 and s1 is 0.2, then 0.012 < s1, and the battery will flow normally. If p1Sdr is 0.3, then 0.3 > s1, and cycle 2 will be triggered. That is to say, if the cell voltages of all the cells in a certain power battery do not have the situation of p1Sdr > s1 in the first stage of self-discharge observation and calculation (cycle 1), the second stage of self-discharge observation and calculation will not be triggered. Otherwise, if the cell voltage of any cell in a certain power battery has the situation of p1Sdr > s1 in cycle 1, it is considered that the power battery may have a slight internal short circuit, which is a greater risk, and the second stage of self-discharge observation and calculation (cycle 2) will be triggered.

[0308] Furthermore, the cloud can complete the observation and calculation and then feed back the results (including normal situations and situations left for further observation in the next stage) to each battery swap station.

[0309] b) If ti>t1+P1_time, the self-discharge rate p1Sdr within the time length P1_time is calculated using a sliding window. For example, the cell voltage from ti to ti+P1_time is extracted for observation and calculation. The self-discharge rate p1Sdr in the first stage is calculated as shown in Formula 3:

[0310]

[0311] Here, ti>t1+P1_time, ti represents the time point when the voltage self-discharge is observed in the first stage, and the time period from t1 observation to ti exceeds the first stage self-discharge observation and calculation time P1_time, that is, it is longer than the time of the first stage. In this way, we can skip the moment t1 and select the voltage from the moment ti to the period of ti+P1_time for analysis.

[0312] in, It represents a time point ti (moment) selected during the period from ti to ti+P1_time when the voltage of cell j is observed. The corresponding voltage of cell j at this time is Indicates that the voltage of cell j is observed earlier than the selected time from ti to ti+P1_time A certain time point t as the starting point i -P1_time (time), the corresponding cell voltage of cell j is Example 2: P1_time = 1 hour, t_polarization = 2 hours, the charging end time of a power battery is t0 = 13:00, the start time of the first stage t1 (cycle 1) is selected, t1 = 16:00, t1-t0>2, which means that the selected t1 is after the depolarization is completed. If ti> t1+1, such as ti = 17:10, the cell voltage of each cell of the power battery corresponding to the period from ti to ti+1 can be extracted for analysis. For example, the cell voltage corresponding to each time point of any cell j of the power battery during the period from 17:30 to 18:30 can be analyzed. For example: t t_i,j =18:30, And the cell voltage v corresponding to 18:30 t_i,j =1, cell voltage at 17:40 p1Sdr=0.36.

[0313] Furthermore, if the calculated p1Sdr>s1 (first threshold), it is judged that there is a relatively serious slight internal short circuit in the j cell, and thus the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, which triggers the interception of the power battery and continues to enter the second stage of self-discharge observation and calculation. If the calculated p1Sdr is not greater than the first threshold s1, for example: p1Sdr≤s1, it is judged that there is no slight internal short circuit in the j cell, and the internal short circuit risk of the power battery where the j cell is located is low and falls within the normal range. It can be circulated normally and replaced for use when an electric vehicle needs it. Among them, the value range of s1 can be 0.1~100. Continuing with Example 2: if p1Sdr is 0.36 and s1 is 0.2, then 0.36>s1, and cycle 2 is triggered. If p1Sdr is 0.1, then 0.1<s1, and the process flows normally. That is to say, if the cell voltages of all cells in a certain power battery do not have the situation of p1Sdr>s1 in the first stage of self-discharge observation and calculation (cycle 1), the second stage of self-discharge observation and calculation will not be triggered. Otherwise, if the cell voltage of any cell in a certain power battery has the situation of p1Sdr>s1 in cycle 1, it is considered that the power battery may have a slight internal short circuit, which is a greater risk, and the second stage of self-discharge observation and calculation (cycle 2) is triggered.

[0314] Furthermore, the cloud can complete the observation and calculation and then feed back the results (including normal situations and situations left for further observation in the next stage) to each battery swap station.

[0315] In b), the sliding window calculation method can accurately calculate the trend change of the monotonically changing curve, save cloud computing resources, and improve computing efficiency.

[0316] Furthermore, a linear fitting method can be used to calculate the self-discharge rate (SDR) of a power battery to replace the calculation method in each stage. That is, the calculation of cycle 1 uses this linear fitting method. For example: using the linear fitting method, a linear fitting calculation is performed on the cell voltage of any j cells among all cells of a power battery within a certain time range, and the slope is used as the self-discharge rate (SDR1), that is, SDR1 = k. The linear fitting formula is as shown in Formula 5:

[0317] v^=v0+kt i Formula 5

[0318] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i The end time of this period. Similarly, the result of k, i.e., the self-discharge rate sdr1, can be compared with s1. For example, in cycle 1, if the calculated self-discharge rate sdr1>s1, then the second phase, cycle 2, is left for further observation. Otherwise, if there is no voltage change in the battery cell, i.e., if the self-discharge rate sdr1>s1, then the power battery is operating normally.

[0319] The second-stage calculation device 6204 is used to, when it is determined that the power battery where the battery cell is located is undergoing second-stage self-discharge observation and calculation, select a time after the end of the first-stage self-discharge observation and calculation to perform second-stage self-discharge observation and calculation on the cell voltage of each battery cell of the power battery, with a time length (P2_time) greater than that of the first-stage self-discharge observation and calculation, to obtain the second-stage self-discharge rate (p2Sdr) of each battery cell, so as to determine whether the power battery where the battery cell is located has an internal short circuit.

[0320] Specifically, the second phase of self-discharge observation and calculation (cycle 2) is for the power battery that is judged to have a high risk of internal short circuit in cycle 1. The start time of the second phase is after the first phase of the power battery in which the battery cell is located is completed, and a certain time is selected as the starting time point, such as Figure 2 t2, t3, etc. are shown. The second-stage self-discharge observation and calculation to obtain the self-discharge rate p2Sdr are similar to the first stage. For example, the time length P2_time can be set to n times P1_time, with the multiple n ranging from 2 to 10. During this stage, the second-stage self-discharge rate p2Sdr can be observed and calculated, as shown in Formula 4:

[0321]

[0322] Among them, t i+P2_time,j It is expressed as a time point t selected from a certain moment ti after the start of the second stage to ti+P2_time during which the voltage of cell j is observed. i+P2_time At this moment, the corresponding voltage of cell j is v i+P2_time,j ;t i,j It is expressed as the time from a certain moment ti after the start of the second stage to ti+P2_time during which the voltage of cell j is observed earlier than t i+P2_time A certain time point t as the starting point i At this moment, the cell voltage of the corresponding j cell is v i,j For examples, see the calculations in Examples 1 and 2 in a) and b) above.

[0323] Furthermore, if the calculated p2Sdr>s2 (second threshold), it is judged that the j cell has a relatively serious slight internal short circuit, so that the internal short circuit risk of the power battery where the j cell is located is also high. The power battery cannot be directly allocated to the electric vehicle for use, and the alarm for the power battery is triggered, the use is stopped, and the return repair process and other subsequent processing are initiated. If the calculated p2Sdr is not greater than the second threshold s2, for example: p2Sdr≤s2, it is judged that the j cell does not have a slight internal short circuit. When all the cells of the power battery where the j cell is located do not have the situation of p2Sdr>s2, it indicates that the internal short circuit risk of the power battery is low and belongs to the normal range. It can be circulated normally and can be replaced and used when an electric vehicle needs it. Among them, the value range of s2 can be 0.1~100.

[0324] Among them, it can be preset that s1>s2>battery cell self-discharge specification.

[0325] Furthermore, the self-discharge rate in the second stage can also be calculated using a linear fitting method to calculate the self-discharge rate sdr2 of a power battery, replacing the calculation method in each stage. That is, the calculation in the second stage uses this linear fitting method. For example: the linear fitting method performs a linear fitting calculation on the voltage of all j cells in a certain time range of a power battery, and uses the slope as the self-discharge rate sdr2, that is, sdr2 = k. The linear fitting formula is as shown in Formula 5:

[0326] v^=v0+kt i Formula 5

[0327] Where v^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t iSimilarly, the result of k, i.e., the self-discharge rate sdr2, can be compared with s2. For example, if sdr2>s2 is calculated in the second stage, an alarm and other subsequent processing are triggered. Otherwise, it indicates that the power battery is normal.

[0328] Through phased design and sliding window design and calculation, the consumption of computing and operating resources is reduced. At the same time, the self-discharge calculation is divided into a shorter observation cycle 1 and a longer observation cycle 2. The changes in the situation in cycle 1 trigger the observation of cycle 2, intercepting a small number of high-risk power batteries. This ensures calculation accuracy while not affecting the battery circulation operation of the entire battery swap station, thus achieving a balanced operation.

[0329] The alarm device 630 is used to trigger safety processing of the power battery according to determining that the power battery where the battery cell is located has an internal short circuit.

[0330] For example, the cloud can complete observation and calculation and then feed back the results to each battery swap station. Figure 1 As shown, after the cloud server completes the calculation, it feeds back the results to each battery swap station, thereby triggering the subsequent processing of one or more power batteries in the corresponding battery swap station, that is, the safety processing of the power battery: alarm, suspension of use, and initiation of return and repair procedures, etc. The alarm can output an alarm message or provide various warning signals such as sound, light and / or electricity.

[0331] In another embodiment, the present invention can implement the cloud-based internal short-circuit monitoring and calculation system for power batteries by setting it into the local control equipment of each battery swap station.

[0332] The present invention is based on the scenario of power batteries being stationary at a battery swap station, which is separated from the complex environment of the electric vehicle side. The scenario has changed, the environment is simpler, and data is easier to collect and accurate, long-lasting and stable. Based on a large amount of more accurate and large-scale data, the factors affecting the stationary working conditions of the battery swap station are simple. Through the ability of cloud computing and storing large amounts of historical data, more accurate results can be calculated, and the success rate of judgment is higher and more accurate. Using methods such as phased triggering interception and sliding windows in the calculation can significantly reduce computing resources and improve efficiency.

[0333] Based on the above method embodiment, the present invention further provides a storage device embodiment. In this storage device embodiment, the storage device stores multiple program codes, which are suitable for being loaded and executed by a processor to perform the above method. For ease of illustration, only the portions relevant to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method section of the embodiment of the present invention.

[0334] Based on the above method embodiment, the present invention further provides a control device embodiment. In this control device embodiment, the device includes a processor and a storage device, wherein the storage device stores multiple program codes, which are suitable for being loaded and executed by the processor to perform the above method. For ease of illustration, only the portions relevant to the embodiment of the present invention are shown. For specific technical details not disclosed, please refer to the method section of the embodiment of the present invention.

[0335] Various embodiments of the present invention monitor and determine minor internal short circuits within a power battery. Preferably, the power battery is located in a stable battery swap station environment with few influencing factors. The electrical signal information of all the power battery cells is collected and stored in chronological order. By using a large amount of stable and accurate long-term historical data under static conditions, the self-discharge of the power battery cells is observed and calculated in stages and steps. By comparing the data with a threshold, it is determined whether the power battery in which the cell is located has an internal short circuit. This allows for more accurate calculation results and a high success rate in judgment. Furthermore, the phased and step-by-step observation and calculation process is primarily divided into a first and second phase, with some steps incorporating a sliding window calculation approach. If the self-discharge rate calculated in the first phase of a power battery cell exceeds a threshold, the observation and calculation process is intercepted and entered into the second phase. The second phase of observation and calculation is then completed, and a determination is made as to whether the self-discharge rate calculated in the second phase exceeds the second threshold. If both exceed, a significant internal short circuit risk is considered, and an alarm is issued for power battery safety measures. Otherwise, if the calculated self-discharge rate does not exceed either the first or second threshold at any phase, the power battery is deemed to have no internal short circuit risk and can be used normally. This balances calculation accuracy with the operational efficiency of the battery swap station. Furthermore, the sliding window approach can more accurately calculate the trend of monotonically changing curves, thereby saving computing resources and improving efficiency. This effectively and accurately implements real-time power battery internal short circuit monitoring in a battery swap station-based environment.

[0336] It will be understood by those skilled in the art that all or part of the processes in the method for implementing the above embodiment of the present invention may also be completed by instructing the relevant hardware through a computer program. The computer program may be stored in a computer-readable storage medium. When the computer program is executed by a processor, it may implement the steps of each of the above method embodiments. The computer program includes computer program code, which may be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium may include: any entity or device, medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signal, telecommunication signal, and software distribution medium that can carry the computer program code. It should be noted that the content contained in the computer-readable medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0337] Furthermore, it should be understood that since the configuration of each module is merely to illustrate the functional units of the system of the present invention, the physical devices corresponding to these modules may be the processor itself, or a portion of the software in the processor, a portion of the hardware, or a combination of software and hardware. Therefore, the number of modules in the figure is merely illustrative.

[0338] Those skilled in the art will appreciate that the various modules in the system can be adaptively split or merged. Such splitting or merging of specific modules does not cause the technical solution to deviate from the principles of the present invention. Therefore, the technical solutions after splitting or merging will fall within the scope of protection of the present invention.

[0339] Thus far, the technical solution of the present invention has been described in conjunction with an embodiment shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for monitoring battery short circuit, applied to battery swap stations, characterized in that: include: Receive and collect electrical signal information from all cells in each power battery; Selecting a starting time for starting the first stage of self-discharge observation and calculation of the cell voltage of each cell in the power battery according to the charging stop time of the power battery and the depolarization time corresponding to the type of the power battery; Starting from the starting time, observing and calculating the cell voltage of each cell in the power battery during the first stage of self-discharge to obtain a first stage self-discharge rate of each cell; Determining whether the power battery in which the battery cell is located should perform second-stage self-discharge observation and calculation based on the first-stage self-discharge rate and the first threshold of each battery cell; If the judgment is no, the power battery operates normally; If the answer is yes, after the first-stage self-discharge observation and calculation is completed, a second-stage self-discharge observation and calculation is started for the cell voltage of each cell of the power battery for a time period longer than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each cell; Determining whether the power battery in which the battery cell is located has an internal short circuit based on the second-stage self-discharge rate and the second threshold of each battery cell, wherein the second threshold is less than the first threshold; According to the result of determining that the power battery has an internal short circuit, an alarm process for the internal short circuit of the power battery is triggered.

2. The method according to claim 1, characterized in that The "receiving and collecting electrical signal information of all cells in each power battery" specifically includes: The power battery is placed at a battery swap station for a long time, and the battery swap station collects the electrical signal information of all cells in each power battery stored at the battery swap station in real time; The real-time collection includes: collecting electrical signal information of all cells of each power battery during the charging process at the battery swap station and during the static process at the battery swap station after charging is completed; The electrical signal information of each battery cell includes at least: single cell voltage, current, temperature, and state of charge (SOC); The battery swap station uploads and synchronizes the collected electrical signal information of all cells of each power battery to the cloud or the local control device of the battery swap station; The cloud or local control equipment of the battery swap station receives the electrical signal information and stores it corresponding to the collection time of real-time collection.

3. The method according to claim 2, characterized in that Obtaining the time to stop charging includes: The charging stopping time of the power battery where the battery cell is located is determined according to the collection time of the electrical signal information corresponding to each battery cell.

4. The method according to claim 3, characterized in that The “determining the time to stop charging the power battery in which the battery cell is located based on the acquisition time of the electrical signal information corresponding to each battery cell” specifically includes: For all cells in the power battery, according to the order of the corresponding collection times, finding the time when the current of all cells is zero from the electrical signal information as the time to stop charging; The "selecting a starting time for starting the first-stage self-discharge observation and calculation of the cell voltage of each cell in the power battery based on the charging stop time of the power battery and the depolarization time corresponding to the type of the power battery" specifically includes: Each type of power battery has a corresponding depolarization time determined after testing; A time point that is longer than the charging stop time plus the depolarization time is selected as the starting time for completing depolarization and performing the first stage self-discharge observation and calculation of the cell voltage of each cell in the power battery.

5. The method according to claim 4, characterized in that The “starting from the starting time, observing and calculating the first-stage self-discharge of the cell voltage of each cell in the power battery to obtain the first-stage self-discharge rate of each cell” specifically includes: During the first stage of self-discharge observation and calculation time length P1_time, calculate the first stage self-discharge rate p1Sdr1 of the observed j-th battery cell: Among them, v i,j is the cell voltage of the jth cell at time ti, v 1,j is the cell voltage of the jth cell at time t1, t i,j Indicates the j-th cell ti moment, t 1,j Indicates t i,j The j-th battery cell before the moment t1.

6. The method according to claim 5, characterized in that The first-stage self-discharge rate p1Sdr1 of the observed j-th battery cell is calculated within the time length P1_time of the first-stage self-discharge observation and calculation, specifically including: If the observation end time point ti is less than the observation start time point t1+P1_time, the cell voltage of the j-th cell from t1 to t1+P1_time is selected for observation, and the self-discharge rate p1Sdr of the j-th cell in the first stage is calculated: in, It represents the time ti selected from the period from t1 to t1+P1_time for observing the cell voltage of the j-th cell. The corresponding cell voltage of the j-th cell is It represents the time selected from t1 to t1+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time t1, the corresponding cell voltage of the j-th cell is If the observation end time point ti> the observation start time point t1+P1_time, then the cell voltage of the j-th cell from ti to ti+P1_time is selected for observation, and the first-stage self-discharge rate p1Sdr of the j-th cell is calculated: in, It represents the time ti selected during the period from ti to ti+P1_time for observing the cell voltage of the j-th cell. At this time, the cell voltage of the j-th cell is It represents the time selected from ti to ti+P1_time during which the cell voltage of the j-th cell is observed earlier than t as the beginning i -P1_time, the corresponding cell voltage of the j-th cell is 7. The method according to claim 4, characterized in that The “starting from the starting time, observing and calculating the first-stage self-discharge of the cell voltage of each cell in the power battery to obtain the first-stage self-discharge rate of each cell” specifically includes: During the first stage of self-discharge observation and calculation, P1_time, all cell voltages of the j-th cell are linearly fitted and calculated: v ^ =v0+kt i Formula 5 Among them, v ^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr1.

8. The method according to claim 5, 6 or 7, wherein "determining whether the power battery in which the battery cell is located should perform second-stage self-discharge observation and calculation based on the first-stage self-discharge rate of each battery cell" specifically includes: Compare the first-stage self-discharge rate p1Sdr or sdr1 of each battery cell with a first threshold s1; When the first-stage self-discharge rate p1Sdr of the battery cell is greater than the first threshold s1 or sdr1 is greater than the first threshold s1, it is determined that the power battery in which the battery cell is located is to perform the second-stage self-discharge observation and calculation; When the first-stage self-discharge rate p1Sdr of the battery cell is less than or equal to the first threshold s1 or sdr1 is less than or equal to the first threshold s1, it is determined that the power battery in which the battery cell is located has no internal short circuit risk and operates normally.

9. The method according to claim 8, characterized in that The step of "if the judgment is yes, then after the first-stage self-discharge observation and calculation is completed, starting the second-stage self-discharge observation and calculation of the cell voltage of each cell of the power battery for a time period longer than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each cell" specifically includes: After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation, wherein the self-discharge rate p2Sdr of the j-th cell is calculated within the time length P2_time of the second-stage self-discharge observation and calculation: Among them, t i+P2_time,j It represents the time period from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed. i+P2_time At this moment, the cell voltage of the jth cell is v i+P2_time,j ;t i,j It represents the time from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed earlier than t i+P2_time t i At this moment, the cell voltage of the jth cell is v i,j ; The time length P2_time of the second stage self-discharge observation and calculation is n times the time length P1_time of the first stage self-discharge observation and calculation, where n∈[2,10].

10. The method according to claim 8, wherein The step of "if the judgment is yes, then after the first-stage self-discharge observation and calculation is completed, starting the second-stage self-discharge observation and calculation of the cell voltage of each cell of the power battery for a time period longer than the first-stage self-discharge observation and calculation to obtain the second-stage self-discharge rate of each cell" specifically includes: After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation. Within the time length P2_time of the second-stage self-discharge observation and calculation, all cell voltages of the j-th cell are linearly fitted and calculated: v ^ =v0+kt i Formula 5 Among them, v ^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr2.

11. The method according to claim 9 or 10, characterized in that The “determining whether the power battery in which the battery cell is located has an internal short circuit based on the second-stage self-discharge rate of each battery cell” specifically includes: Comparing the second-stage self-discharge rate p2Sdr or sdr2 of each battery cell with a second threshold s2; When the second-stage self-discharge rate p2Sdr of the battery cell is greater than the second threshold s2 or sdr2 is greater than the second threshold s2, it is determined that the power battery in which the battery cell is located has an internal short circuit; When the second-stage self-discharge rate p2Sdr of the battery cell is less than or equal to the second threshold s2 or sdr2 is less than or equal to s2, it is determined that the power battery in which the battery cell is located does not have an internal short circuit risk and is in normal operation; The preset first threshold s1>the second threshold s2>the cell self-discharge specification, and the value range of s1 and s2 is 0.1-100.

12. The method according to claim 11, characterized in that The "feedback based on the result of determining that the power battery has an internal short circuit, so as to trigger an alarm process for the existence of an internal short circuit in the power battery" specifically includes: After the cloud or local control equipment at the battery swap station completes the observation and calculation at each stage, it will feedback the result of whether the power battery has an internal short circuit to the corresponding battery swap station. When the result received by the battery swap station is that the power battery has an internal short circuit, the battery swap station triggers an alarm process for the internal short circuit of the power battery, including: alarming, stopping use and initiating a return and repair process.

13. A system for monitoring battery short circuits, used in battery swap stations, characterized in that: include: A receiving storage device, used to receive the collected electrical signal information of all cells in each power battery; The staged calculation device is used to observe the self-discharge and calculate the self-discharge rate based on the cell voltage in the electrical signal information of each cell after depolarization is completed, so as to determine whether the power battery where the cell corresponding to the self-discharge rate is located has an internal short circuit, specifically including: The first stage starting device is used to select a starting time for starting the first stage of self-discharge observation and calculation of the cell voltage of each cell in the power battery according to the time when the power battery stops charging and the depolarization time corresponding to the type of the power battery, The first-stage calculation device is used to perform a first-stage self-discharge observation and calculation on the cell voltage of each cell in the power battery from the starting time to obtain a first-stage self-discharge rate of each cell; based on the first-stage self-discharge rate of each cell and a first threshold, determine whether the power battery in which the cell is located should perform a second-stage self-discharge observation and calculation; if not, the power battery is operating normally. a second-stage calculation device configured to, if the judgment is yes, start, after the first-stage self-discharge observation and calculation, performing a second-stage self-discharge observation and calculation on the cell voltage of each cell of the power battery for a period longer than the first-stage self-discharge observation and calculation, to obtain a second-stage self-discharge rate of each cell; and determine whether the power battery in which the cell is located has an internal short circuit based on the second-stage self-discharge rate of each cell and a second threshold value, wherein the second threshold value is less than the first threshold value; The alarm device triggers an alarm process for the internal short circuit of the power battery based on feedback of a result of determining that the power battery has an internal short circuit.

14. The system according to claim 13, wherein: The receiving storage device specifically includes: The power battery is placed at a battery swap station for a long time, and the battery swap station collects the electrical signal information of all cells in each power battery stored at the battery swap station in real time; The real-time collection includes: collecting electrical signal information of all cells of each power battery during the charging process at the battery swap station and during the static process at the battery swap station after charging is completed; The electrical signal information of each battery cell includes at least: single cell voltage, current, temperature, and state of charge (SOC); The battery swap station uploads and synchronizes the collected electrical signal information of all cells of each power battery to the cloud or the local control device of the battery swap station; The cloud or local control equipment of the battery swap station receives the electrical signal information and stores it corresponding to the collection time of real-time collection.

15. The system according to claim 14, wherein: The staged calculation device specifically further includes: The charging stop time device is used to determine the charging stop time of the power battery where the battery cell is located according to the collection time of the electrical signal information corresponding to each battery cell.

16. The system according to claim 15, wherein: The device for stopping charging specifically comprises: finding the time when the current of all cells in the power battery is 0 from the electrical signal information in the order of the corresponding collection time as the time for stopping charging; The device for selecting the start of the first stage specifically includes: a depolarization time determined after testing corresponding to each type of the power battery; selecting a time point greater than the time of stopping charging plus the length of the depolarization time as the starting time for completing depolarization and performing the first stage self-discharge observation and calculation of the cell voltage of each cell in the power battery.

17. The system according to claim 16, wherein: The first-stage computing device specifically includes: During the first stage of self-discharge observation and calculation time length P1_time, calculate the first stage self-discharge rate p1Sdr1 of the observed j-th battery cell: Among them, v i,j is the cell voltage of the jth cell at time ti, v 1,j is the cell voltage of the jth cell at time t1, t i,j Indicates the j-th cell ti moment, t 1,j Indicates t i,j The j-th battery cell before the moment t1.

18. The system according to claim 17, wherein: The first-stage computing device further includes: If the observation end time point ti is less than the observation start time point t1+P1_time, the cell voltage of the j-th cell from t1 to t1+P1_time is selected for observation, and the self-discharge rate p1Sdr of the j-th cell in the first stage is calculated: in, It represents the time ti selected from the period from t1 to t1+P1_time for observing the cell voltage of the j-th cell. The corresponding cell voltage of the j-th cell is It represents the time selected from t1 to t1+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time t1, the corresponding cell voltage of the j-th cell is If the observation end time point ti> the observation start time point t1+P1_time, then the cell voltage of the j-th cell from ti to ti+P1_time is selected for observation, and the first-stage self-discharge rate p1Sdr of the j-th cell is calculated: in, It represents the time ti selected during the period from ti to ti+P1_time for observing the cell voltage of the j-th cell. At this time, the cell voltage of the j-th cell is It represents the time selected from ti to ti+P1_time during which the cell voltage of the j-th cell is observed earlier than As the starting time ti-P1_time, the corresponding cell voltage of the j-th cell is 19. The system according to claim 16, wherein: The first-stage computing device specifically includes: During the first stage of self-discharge observation and calculation, P1_time, all cell voltages of the j-th cell are linearly fitted and calculated: v ^ =v0+kt i Formula 5 Among them, v ^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, ti is the end time point of this period, and the slope k = self-discharge rate sdr1.

20. The system according to claim 17, 18 or 19, characterized in that The first-stage computing device specifically includes: Compare the first-stage self-discharge rate p1Sdr or sdr1 of each battery cell with a first threshold s1; When the first-stage self-discharge rate p1Sdr of the battery cell is greater than the first threshold s1 or sdr1 is greater than the first threshold s1, it is determined that the power battery in which the battery cell is located is to perform the second-stage self-discharge observation and calculation; When the first-stage self-discharge rate p1Sdr of the battery cell is less than or equal to the first threshold s1 or sdr1 is less than or equal to the first threshold s1, it is determined that the power battery in which the battery cell is located has no internal short circuit risk and operates normally.

21. The system according to claim 20, wherein: The second-stage computing device specifically includes: After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation, wherein the self-discharge rate p2Sdr of the j-th cell is calculated within the time length P2_time of the second-stage self-discharge observation and calculation: Among them, t i+P2_time,j It represents the time period from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed. i+P2_time At this moment, the cell voltage of the jth cell is v i+P2_time,j ;t i,j It represents the time from time ti to time ti+P2_time during the second stage of self-discharge observation and calculation, during which the cell voltage of the j-th cell is observed earlier than t i+P2_time t i At this moment, the cell voltage of the jth cell is v i,j ; The time length P2_time of the second stage self-discharge observation and calculation is n times the time length P1_time of the first stage self-discharge observation and calculation, where n∈[2,10].

22. The system according to claim 20, wherein the second-stage computing device comprises: After the first-stage self-discharge observation and calculation is completed, the second-stage self-discharge observation and calculation is performed on the cell voltage of each cell in the power battery to be subjected to the second-stage self-discharge observation and calculation. Within the time length P2_time of the second-stage self-discharge observation and calculation, all cell voltages of the j-th cell are linearly fitted and calculated: v ^ =v0+kt i Formula 5 Among them, v ^ is the voltage of all j cells within a certain period of time, v0 is the initial voltage at the beginning of this time range, t i is the end time point of this period, and the slope k = self-discharge rate sdr2.

23. The system according to claim 21 or 22, wherein the second stage computing device further comprises: Comparing the second-stage self-discharge rate p2Sdr or sdr2 of each battery cell with a second threshold s2; When the second-stage self-discharge rate p2Sdr of the battery cell is greater than the second threshold s2 or sdr2 is greater than the second threshold s2, it is determined that the power battery in which the battery cell is located has an internal short circuit; When the second-stage self-discharge rate p2Sdr of the battery cell is less than or equal to the second threshold s2 or sdr2 is less than or equal to s2, it is determined that the power battery in which the battery cell is located does not have an internal short circuit risk and is in normal operation; The preset first threshold s1>the second threshold s2>the cell self-discharge specification, and the value range of s1 and s2 is 0.1-100.

24. The system according to claim 23, wherein: The alarm device specifically includes: After the cloud or local control equipment at the battery swap station completes the observation and calculation at each stage, it will feedback the result of whether the power battery has an internal short circuit to the corresponding battery swap station. When the result received by the battery swap station is that the power battery has an internal short circuit, the battery swap station triggers an alarm process for the internal short circuit of the power battery, including: alarming, stopping use and initiating a return and repair process.

25. A storage device storing a plurality of program codes, characterized in that: The program code is suitable for being loaded and run by a processor to execute the method for monitoring battery short circuit according to any one of claims 1 to 12.

26. A control device comprising a processor and a storage device, wherein the storage device is adapted to store a plurality of program codes, wherein: The program code is suitable for being loaded and executed by the processor to execute the method for monitoring battery short circuit according to any one of claims 1 to 12.

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