A battery module early warning control method and device

Abstract

The present invention provides a battery module early warning control method and device, which relate to the field of battery technology. The method is applied to a battery module including at least two groups of parallel units, including: obtaining the current change of the target parallel unit of the battery module and the normal parallel unit adjacent to the target parallel unit; determining the sensitivity of the target battery cell of the target parallel unit according to the current change; if the sensitivity is in a first preset range, sending a fault degree signal to the battery system. The method and device provided by the present invention can timely detect abnormalities of the battery system based on the current change of the target battery cell determined by the current, advance the early warning time to the greatest extent, and improve the safety of the battery module. In addition, the present invention has good early warning signal sensitivity, and can be applied to battery structures with different numbers of battery cells in parallel. At the same time, the sensitivity can be further optimized by optimizing the number of battery cells in the target parallel unit.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a battery module early warning control method and device. Background Art

[0002] Lithium-ion batteries have been widely used in new energy vehicles due to their high energy density, long service life and no memory effect. As the number of lithium batteries increases and their energy density improves, safety issues are becoming more and more prominent. The causes of thermal runaway in lithium-ion batteries are very complex and can be mainly divided into two aspects: inherent defects and abuse. These two causes, when developed to a certain extent, will lead to severe thermal runaway of the battery, endangering the safety of passengers' lives and property.

[0003] At present, from battery cells to module systems to vehicle manufacturers, work is being done to improve battery safety. Battery cell companies mainly improve the safety performance of battery cells by selecting the main materials and optimizing the design of battery cell structures; module and system companies mainly improve battery safety characteristics by structural design, thermal management, heat spread suppression and fire extinguishing of modules. In recent years, with the emergence of new energy vehicle safety issues, vehicle manufacturers have also rapidly invested in the safety development of new energy vehicles. It mainly collects various indicators such as the voltage and temperature of the battery cells by building sensors into the battery system, and performs alarms and early warnings. As the last line of defense for the safety of new energy vehicles. The timeliness and accuracy of early warnings and alarms are very important. At present, the early warning and alarm methods used in existing technologies are only achieved by monitoring the voltage and temperature rise of the battery. There are still a large number of accidents that cannot be timely, or even cannot be warned and alarmed at all, and the purpose of 100% thermal runaway monitoring cannot be achieved. Therefore, the current research and development of early warnings and alarms for battery modules needs to be improved.

[0004] According to the battery parallel unit structure and the reasonable abnormal factor of the internal resistance of the battery cell used, the method of the present invention is used to determine the early warning device and method for the battery and structure, as well as the preset range of alarm sensitivity. Summary of the invention

[0005] The embodiments of the present invention provide a battery module early warning control method and device to solve the problem that the prior art method for monitoring battery thermal runaway is still incomplete and has safety risks.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] An embodiment of the present invention provides a battery module early warning control method, which is applied to a battery module including at least two groups of parallel units, including:

[0008] Acquire current changes of a target parallel unit of the battery module and normal parallel units adjacent to the target parallel unit;

[0009] Determining the sensitivity of the target battery cell of the target parallel unit according to the current change;

[0010] If the sensitivity is within a first preset range, a fault degree signal is sent to the battery system.

[0011] Optionally, the battery module early warning control method further includes:

[0012] Obtaining the target total current of the normal parallel unit and the number of cells of the normal parallel unit;

[0013] The ratio of the target total current to the number of second battery cells of the normal parallel unit is calculated, and the current of each normal battery cell of the normal parallel unit is determined.

[0014] Optionally, the obtaining of current changes of a target parallel unit of the battery module and a normal parallel unit adjacent to the target parallel unit includes:

[0015] Obtaining the total current of the target parallel unit and the number of cells of the target parallel unit;

[0016] Determining the current of the target battery cell according to the total current of the target parallel unit and the number of battery cells;

[0017] Obtaining the current of the normal battery cell of the normal parallel unit;

[0018] Calculating a difference between the current of the target battery cell and the current of the normal battery cell, and determining the difference as the current variation;

[0019] Wherein, the position of the normal battery cell corresponds to the position of the target battery cell.

[0020] Optionally, determining the sensitivity of the target battery cell according to the current change includes:

[0021] The ratio of the current change to the normal current of the target battery cell is calculated and determined as the sensitivity of the target battery cell.

[0022] Optionally, the current change is expressed as:

[0023]

[0024] Wherein, ΔI represents the current change, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of battery cells, and I represents the total current of the target parallel unit.

[0025] Optionally, the method further includes:

[0026] In the case where the target cell is a cell monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell tends to increase; if the target cell has an internal resistance increase fault, the current of the target cell tends to decrease; or,

[0027] In the case where the target cell is a cell not monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell tends to decrease, and if the target cell has an internal resistance increase fault, the current of the target cell tends to increase.

[0028] Optionally, the method further includes:

[0029] Acquire the monitoring quantity of the monitoring cells of the target parallel unit through a sensor;

[0030] Determining a monitoring current percentage according to a ratio of the monitoring quantity to the number of battery cells;

[0031] The sensitivity of the target battery cell is determined according to the monitored current percentage and the current change.

[0032] Optionally, when the monitoring cell includes the target cell, the formula for determining the sensitivity of the target cell is expressed as:

[0033]

[0034] Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of the battery cells, and y represents the percentage of the monitored current.

[0035] Optionally, when the monitoring cell does not include the target cell, the formula for determining the sensitivity of the target cell is expressed as:

[0036]

[0037] Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, and n represents the number of the battery cells.

[0038] Optionally, the method further includes:

[0039] When the target battery cell of the target parallel unit of the battery module is not faulty, monitoring the charge state of the target battery cell;

[0040] If the charge state of the target battery cell is inconsistent with self-discharge, a thermal runaway warning signal is sent to the battery system.

[0041] The embodiment of the present invention further provides a battery module early warning control device, which is applied to a battery module including at least two groups of parallel units, including:

[0042] An acquisition module, used for acquiring current changes of a target parallel unit of the battery module and normal parallel units adjacent to the target parallel unit;

[0043] A first determination module, configured to determine the sensitivity of a target cell of the target parallel unit according to the current variation;

[0044] The sending module is used to send a fault degree signal to the battery system if the sensitivity is within a first preset range.

[0045] An embodiment of the present invention further provides a readable storage medium, on which a program is stored, and when the program is executed by a processor, the steps of the battery module early warning control method as described above are implemented.

[0046] The beneficial effects of the present invention are:

[0047] In the above technical solution, the sensitivity of the target battery cell is determined by determining the current change of the target parallel unit with fault and the normal parallel unit adjacent to the target parallel unit. If the sensitivity is within the first preset range, a fault degree signal is sent to the battery system. On the one hand, the present invention determines thermal runaway based on current information, and can give an early warning when the current is abnormal and thermal runaway just begins; on the other hand, the technical solution of the present invention does not require modification of the battery pack or battery module of the prior art, and the method of the present invention can be used for early warning monitoring, which improves practicality and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram showing a flow chart of a battery module early warning control method provided by an embodiment of the present invention;

[0049] Figure 2 One of the circuit schematic diagrams of the target parallel unit provided by the embodiment of the present invention is shown;

[0050] Figure 3 One of the corresponding graphs of the curves showing the abnormal internal resistance factor-sensitivity of the abnormal battery cell provided by the embodiment of the present invention;

[0051] Figure 4 A second corresponding graph showing the abnormal internal resistance factor-sensitivity curve of an abnormal battery cell provided by an embodiment of the present invention;

[0052] Figure 5 A second circuit diagram showing a target parallel unit provided by an embodiment of the present invention;

[0053] Figure 6One of the corresponding graphs of the monitoring current percentage-sensitivity curve provided by the embodiment of the present invention;

[0054] Figure 7 A second corresponding graph showing a curve of monitoring current percentage-sensitivity provided in an embodiment of the present invention;

[0055] Figure 8 A third graph showing a curve of monitoring current percentage-sensitivity provided in an embodiment of the present invention;

[0056] Fig. 9 A fourth corresponding graph showing a curve of monitoring current percentage-sensitivity provided in an embodiment of the present invention;

[0057] Fig.10 A module schematic diagram showing a battery module early warning control device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail in conjunction with the accompanying drawings and specific embodiments. In the following description, specific details such as specific configurations and components are provided only to help fully understand the embodiments of the present invention. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. In addition, for clarity and brevity, the description of known functions and structures is omitted.

[0059] It should be understood that the references to "one embodiment" or "an embodiment" throughout the specification mean that the specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present invention. Therefore, the references to "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0060] In various embodiments of the present invention, it should be understood that the size of the serial numbers of the following processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0061] It should be known that, currently, lithium-ion battery modules generally adopt a structure in which multiple battery cells are first connected in parallel and then in series. A battery module or system with this structure can only detect the total current in the total positive circuit during use, and cannot monitor the current of each parallel battery cell. When a battery cell in a parallel unit fails, the abnormal voltage signal of the parallel unit will be largely masked due to the presence of other normal parallel batteries, resulting in increased timeliness and difficulty of early warning. When the voltage signal of the parallel unit is obviously abnormal, the abnormal battery cell is already on the verge of being out of control, and it is impossible to reserve sufficient alarm and disposal time, resulting in the occurrence of thermal runaway. In view of the problem that the prior art method of monitoring battery thermal runaway is still incomplete and has safety risks, the present invention provides a battery module early warning control method and device.

[0062] It should be known that the amount of heat generated by thermal runaway in the battery module is determined by the current and the ohmic internal resistance. The current is an indicator that directly reflects the heat generation, so it is more direct and accurate to use it as an early warning.

[0063] like Figure 1 As shown, an embodiment of the present invention provides a battery module early warning control method, which is applied to a battery module including at least two groups of parallel units, including:

[0064] Step 100, obtaining current changes of a target parallel unit of the battery module and normal parallel units adjacent to the target parallel unit;

[0065] Here, the target parallel unit is a parallel unit when a fault occurs in the battery module.

[0066] Step 200, determining the sensitivity of the target cell of the target parallel unit according to the current variation;

[0067] Step 300: If the sensitivity is within a first preset range, a fault degree signal is sent to the battery system.

[0068] In this embodiment, since the current is an indicator that directly reflects the heat generation, the sensitivity between the target battery cell of the target parallel unit with a fault and the normal battery cell of the normal parallel unit adjacent to the target parallel unit can be determined through steps 100 to 200, so that the degree of deviation or discreteness can be analyzed. In step 300, the abnormal range of the sensitivity is increased, that is, the first preset range. When the sensitivity is in the first preset range, a fault degree signal is sent to the battery system. The fault degree signal has multiple dimensional information, including but not limited to sensitivity, abnormal internal resistance factor of abnormal battery cell, number of battery cells of target parallel unit, etc., which can determine the specific risk of thermal runaway of the target parallel unit of the battery module. Here, the first preset range changes according to different actual situations.

[0069] like Figure 2 As shown, the method also includes:

[0070] Step 410, obtaining the target total current of the normal parallel unit and the number of cells of the normal parallel unit;

[0071] Step 420 , calculating a ratio of the target total current to the number of second battery cells in the normal parallel unit, and determining the ratio as the current of each normal battery cell in the normal parallel unit.

[0072] It should be noted that, in the present invention, before obtaining the target total current of the normal parallel unit, at least one current sensor has been added to each parallel unit of the battery module. The current sensor, such as a shunt or a Hall current sensor, but not limited to these two devices, is used to collect the current of one or several battery cells in each parallel unit, and realize safety alarm and early warning by monitoring the current.

[0073] like Figure 2 The figure is a circuit diagram of a normal parallel unit. In this embodiment, the target total current I of the normal parallel unit and the number of cells n of the normal parallel unit are obtained, that is, a normal parallel unit is composed of n cells in parallel, wherein the voltage of the normal parallel unit is U; the target total current I and the second number of cells I of the normal parallel unit are calculated. n The current of each normal parallel unit can be expressed by formula 1: I n =I / n, the I n It can represent the current of the nth battery cell detected by the current sensor.

[0074] This embodiment adds a current sensor inside the module to collect the current of different branches inside the parallel unit to perform thermal runaway warning and alarm. According to Ohm's law, the current value of the normal battery cell of any parallel unit in each battery module can be calculated, and more direct safety warning and alarm can be achieved by detecting the change in the current value of each normal battery cell in the branch, thereby improving the timeliness and accuracy of the warning, increasing safety, and reducing the number of thermal runaways in electric vehicles.

[0075] Optionally, the step 100 includes:

[0076] Step 110, obtaining the total current of the target parallel unit and the number of cells of the target parallel unit;

[0077] Step 120, determining the current of the target battery cell according to the total current of the target parallel unit and the number of battery cells;

[0078] Step 130, obtaining the current of the normal battery cell of the normal parallel unit;

[0079] Step 140, calculating a difference between the current of the target battery cell and the current of the normal battery cell, and determining the difference as the current variation;

[0080] Wherein, the position of the normal battery cell corresponds to the position of the target battery cell.

[0081] In this embodiment, through step 110 and step 120, combined with formula 1, the current of the target battery cell can be obtained; combined with the number of batteries, the specific position of the target battery cell in the target parallel circuit can also be determined. Because the battery module used in this embodiment includes at least two groups of parallel units, the current of a normal parallel unit adjacent to the target parallel circuit can be obtained. According to the corresponding relationship between the position of the target battery cell and the position of the normal battery cell, the current of the normal battery cell of the normal parallel unit can be determined through step 130. Here, the current of the normal battery cell can also be calculated using formula 1; the difference between the two, that is, the difference between the current of the target battery cell and the current of the normal battery cell, can be calculated through step 140 to determine the current change. This embodiment can achieve the purpose of early warning and improve the accuracy of the data by comparing the deviation degree and change amount of the current of the target battery cell with the current of other normal batteries (the current of the normal battery cell of a normal parallel unit adjacent to the target parallel circuit).

[0082] Specifically, the formula for the current change is expressed as:

[0083]

[0084] Wherein, ΔI represents the current change, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of battery cells, and I represents the total current of the target parallel unit.

[0085] It should be noted that, since the target battery cell is the faulty battery cell of the target parallel unit of the battery module, the internal resistance of the target battery cell will change. Therefore, the change in internal resistance can be used to indicate the degree of battery cell failure. Assume that the internal resistance changes from the normal internal resistance R to the faulty internal resistance xR, where x represents the abnormal internal resistance factor of the abnormal battery cell. Formula 2 can be calculated using Formula 1 and step 100.

[0086] Optionally, the step 200 includes:

[0087] The ratio of the current change to the normal current of the target battery cell is calculated and determined as the sensitivity of the target battery cell.

[0088] Specifically, the sensitivity of the target cell is expressed as:

[0089]

[0090] Among them, ΔI represents the current change, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of battery cells, and I represents the total current of the target parallel unit.

[0091] In this embodiment, it can be determined that the number of cells in the target parallel unit has an impact on the sensitivity. It can be seen from the above formulas 2 and 3 that when the abnormal internal resistance factor x of the abnormal cell of the target cell is fixed, the larger the number n of cells in the target parallel unit, the smaller the value of ΔI, the lower the sensitivity, and the less obvious the warning signal; when the number n of cells is constant, the larger the abnormal internal resistance factor x of the abnormal cell of the target cell, the greater the impact on the current change ΔI, and the more obvious the warning signal. Therefore, the present invention should not have too many cells in the target parallel unit, and the preferred range is between 2 and 7, which is more applicable. The present invention can be combined with the number of cells in the target parallel unit to optimize the design of the current collection method and quantity to achieve the highest warning sensitivity, and the warning accuracy coverage is high.

[0092] Optionally, the method further includes:

[0093] In the case where the target cell is a cell monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell tends to increase; if the target cell has an internal resistance increase fault, the current of the target cell tends to decrease; or,

[0094] In the case where the target battery cell is a battery cell monitored by a sensor, if the target battery cell is a battery cell not monitored by a sensor, if the target battery cell has an internal resistance reduction fault, the current of the target battery cell shows a decreasing trend; if the target battery cell has an internal resistance increase fault, the current of the target battery cell shows an increasing trend.

[0095] In a specific embodiment, when the target cell is a cell monitored by a sensor, if the target cell has a fault such as an internal short circuit that reduces the internal resistance, the current of the target cell tends to increase; if the target cell has a fault such as accelerated aging that increases the internal resistance, the current of the target cell tends to decrease. According to Formula 3, the following formula can be constructed: Figure 3 One of the corresponding graphs of the abnormal internal resistance factor-sensitivity curve of the abnormal battery shown in FIG. Figure 3 It can be seen that when the abnormal internal resistance factor x of the abnormal battery cell is 1, the sensitivity does not change with the number of battery cells.

[0096] In another specific embodiment, when the target cell is a cell not monitored by a sensor, if the target cell has a fault such as an internal short circuit that reduces the internal resistance, the current of the target cell tends to decrease; if the target cell has a fault such as accelerated aging that increases the internal resistance, the current of the target cell tends to increase. According to Formula 3, the following formula can be constructed: Figure 4 The second corresponding graph of the abnormal internal resistance factor-sensitivity curve of the abnormal battery cell is shown in FIG. Figure 4 It can also be seen that when the abnormal internal resistance factor x of the abnormal battery cell is 1, the sensitivity does not change with the number of battery cells.

[0097] comprehensive Figure 3 and Figure 4 It can be seen that when the abnormal internal resistance factor x of the abnormal battery cell of the target battery cell is fixed, the larger the number n of the battery cells in the target parallel unit, the smaller the value of ΔI, the lower the sensitivity, and the less obvious the warning signal; when the number n of battery cells is constant, the larger the abnormal internal resistance factor x of the abnormal battery cell of the target battery cell, the greater the impact on the current change ΔI, and the more obvious the warning signal, which further verifies the accuracy of Formula 3.

[0098] from Figure 3 Hehe Figure 4 It can also be intuitively seen that the corresponding relationship between the abnormal internal resistance factor and the sensitivity of the abnormal battery cell when the target battery cell is monitored by a sensor and when the target battery cell is monitored by a non-sensor; the case where the abnormal internal resistance factor x of the abnormal battery cell is less than 1 and the case where the abnormal internal resistance factor x of the abnormal battery cell is greater than 1 can also be analyzed; the present invention can obtain different fault degree signals through the sensitivity.

[0099] In an alternative embodiment, if Figure 5 As shown, the method also includes:

[0100] Step 510, obtaining the monitoring quantity of the monitoring cells of the target parallel unit through a sensor;

[0101] Step 520, determining a monitoring current percentage according to a ratio of the monitoring quantity to the number of battery cells;

[0102] Step 530: Determine the sensitivity of the target battery cell according to the monitored current percentage and the current change.

[0103] It should be known that the number of branch currents monitored by the sensor in the target parallel unit also affects the sensitivity of the target battery cell.

[0104] In this embodiment, the sensor includes but is not limited to a shunt or a Hall current sensor. Before step 510, the sensor is set on one of the branches of the target parallel unit, such as Figure 5 As shown, the number of monitored cells of the target parallel unit is obtained by a sensor, which can be understood here as the sensor monitoring m branch currents, where m is less than the number of cells n; through step 520, the ratio of the monitored number m to the number of cells n is calculated to determine the percentage of monitored current, that is, y=m / n, wherein y represents the percentage of monitored current, representing the proportion of the detected current to the total current, and the value of y can only be a fixed percentage according to the size of the monitored number n, and cannot take any value; and the sensitivity of the target cell is determined through step 530, so as to achieve the purpose of adjusting the percentage of monitored current to adjust the sensitivity of the target cell, that is, the design of current warning should collect the number of branch currents according to the target number of cells in the target parallel unit to achieve maximum sensitivity.

[0105] Specifically, when the monitored battery cell includes the target battery cell, the formula of step 530 is expressed as:

[0106]

[0107] Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of the battery cells, and y represents the percentage of the monitored current.

[0108] It should be noted that the monitoring cell includes the target cell, that is, the location where the target cell of the target parallel unit of the battery module fails is on one of the branches of the monitoring cell.

[0109] For example, when the abnormal internal resistance factor of the abnormal cell is 0.5 (less than 1), the formula 4 is used to construct Figure 6 , Figure 6 One of the corresponding graphs of the monitoring current percentage-sensitivity curve constructed; when the abnormal internal resistance factor of the abnormal battery cell is 1.5 (greater than 1), according to the formula 4, Figure 7 , Figure 7 The second corresponding graph of the monitoring current percentage-sensitivity curve constructed; Figure 6 and Figure 7It can be seen that when the monitored cell includes the target cell, the sensitivity of the target cell increases rapidly as the number of cells in the target parallel unit decreases, and the lower the percentage of the monitored current, the higher the sensitivity. Therefore, to design a highly sensitive current warning structure, it is necessary to comprehensively consider the ratio of the number of monitored cells to the number of cells, that is, the size of the percentage of the monitored current, so that the size of the sensitivity can be adjusted.

[0110] Specifically, when the monitoring cell does not include the target cell, the formula for determining the sensitivity of the target cell is expressed as:

[0111]

[0112] Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, and n represents the number of the battery cells.

[0113] It should be noted that the monitoring cell does not include the target cell, that is, the location where the target cell of the target parallel unit of the battery module fails is not on one of the branches of the monitoring cell, but on the non-detection branch of the target parallel unit of the battery module.

[0114] For example, when the abnormal internal resistance factor of the abnormal cell is 0.5 (less than 1), the formula 5 is constructed as follows: Figure 8 , Figure 8 The third corresponding graph of the monitoring current percentage-sensitivity curve constructed; when the abnormal internal resistance factor of the abnormal cell is 1.5 (greater than 1), according to the formula five, Fig. 9 , Fig. 9 The fourth corresponding figure of the curve of monitoring current percentage-sensitivity constructed; from Figure 8 and Fig. 9 It can be seen that when the monitoring cell does not include the target cell, the sensitivity is not related to the percentage of the monitored current, but only to the number of the target cell, and the fewer the number of cells, the higher the sensitivity. Therefore, when designing a highly sensitive current warning structure, it is necessary to comprehensively consider the number of cells, so that the sensitivity can be adjusted. Preferably, the number of cells is within the range of 2 to 7.

[0115] comprehensive Figures 6 to 9 As shown, the position where the sensor collects data and the number of battery cells in the target parallel unit have an obvious influence on determining the sensitivity. Therefore, the method of the present invention can comprehensively design the number of collected branch currents according to the number of battery cells in the target parallel unit in the battery module to achieve maximum warning sensitivity.

[0116] The present invention is to design a specific battery module early warning control method of the present invention in combination with the battery cell parameters (especially the specification of R) and the number of batteries in the parallel unit (n) during the design stage of the power battery system. In a specific embodiment, for example, the battery module uses a battery cell with a certain R specification of R±0.1R, which is a 4-parallel structure, and is designed based on the above method (using the above various formulas, assigning n to 4 and x to 0.9-1.1). When collecting a branch, the range of the sensitivity S is -4.8-5.3%, (for example, the range of the sensitivity S is based on Figure 3 The range is -4.8-5.3% and Figure 4 The range is -2.7-2.3%, take the maximum range value of the two), then when the actual abnormal factor of the resistance exceeds the range of 0.9-1.1, the value of the sensitivity S will also exceed the normal -4.8-5.3%, and the battery module is judged to be abnormal and an alarm is issued; similarly, if n=4 parallel units: when collecting 2 branch currents, the x value is 1.5, then the S is about -10% (such as Figure 7 As shown), it exceeds the normal S preset value of about -2% (x maximum value 1.1) (Formula 4) under this condition, and an alarm is issued.

[0117] Optionally, the method further includes:

[0118] Step 600, when the target battery cell of the target parallel unit of the battery module has not failed, monitoring the charge state of the target battery cell;

[0119] Step 700: If the state of charge of the target battery cell is inconsistent with self-discharge, a thermal runaway warning signal is sent to the battery system.

[0120] In this embodiment, when the target battery cell of the target parallel unit of the battery module has not failed, the internal current change of the target parallel unit when the vehicle is in a non-working (parked and stationary) state can also be monitored, that is, the charge state of the target battery cell is monitored, so as to issue an early warning for abnormal conditions such as over-discharge of the current in the target parallel unit due to internal short circuit and poor battery cell consistency of the target parallel unit. Specifically, in step 600, the state of charge (SOC) of the target battery cell is monitored. When the target parallel unit has not failed, it can be known from the SOC that the voltage and self-discharge degree of the target parallel unit are consistent. In step 700, if the state of charge of the target battery cell is inconsistent with the self-discharge, it may be caused by an internal battery cell short circuit of the target parallel unit, or a battery cell state failure of the target parallel unit, which will cause a complementary current to be generated inside the target parallel unit. This embodiment can realize the monitoring of the complementary current, and can warn of the abnormalities caused by the self-discharge abnormality and inconsistency of any target parallel unit of the battery module, thereby making up for the disadvantage that the prior art cannot warn in the parking state.

[0121] In summary, the present invention can significantly improve the advance warning and accurate coverage of the battery system. Based on the heat generation mechanism of thermal runaway, the use of current as a signal for early warning has the advantages of high sensitivity, strong reliability and high advance warning. As soon as an abnormality occurs in the battery cell in the target parallel unit, an early warning can be issued by identifying the change in current, which can provide early warning to the greatest extent, and gain as much time as possible for the control of thermal runaway and the safety of passengers' lives and property; at the same time, it can also monitor the internal self-discharge and micro-short circuit of the target parallel unit in the non-working state; the current-based early warning method of the present invention can detect battery module abnormalities in time, advance the warning time to the greatest extent, and can also collect the location of the target battery cell and set the number of batteries in the target parallel unit to improve the sensitivity of the current early warning.

[0122] like Fig.10 As shown, the embodiment of the present application also provides a battery module early warning control device, which is applied to a battery module including at least two groups of parallel units, including:

[0123] An acquisition module 10 is used to acquire current changes of a target parallel unit of the battery module and normal parallel units adjacent to the target parallel unit;

[0124] A first determination module 20, configured to determine the sensitivity of a target cell of the target parallel unit according to the current variation;

[0125] The sending module 30 is used to send a fault degree signal to the battery system if the sensitivity is within a first preset range.

[0126] Optionally, the device further comprises:

[0127] A second acquisition module is used to acquire the target total current of the normal parallel unit and the number of cells of the normal parallel unit;

[0128] The calculation module is used to calculate the ratio of the target total current to the number of second battery cells of the normal parallel unit, and determine the current of each normal battery cell of the normal parallel unit.

[0129] Optionally, the acquisition module 10 includes:

[0130] A first acquisition unit, used to acquire the total current of the target parallel unit and the number of cells of the target parallel unit;

[0131] A first calculation unit, configured to determine the current of the target battery cell according to the total current of the target parallel unit and the number of battery cells;

[0132] A second acquisition unit, used to acquire the current of the normal battery cell of the normal parallel unit;

[0133] A second calculation unit, used for calculating a difference between the current of the target battery cell and the current of the normal battery cell, and determining the difference as the current variation;

[0134] Wherein, the position of the normal battery cell corresponds to the position of the target battery cell.

[0135] Optionally, the first determining module 20 includes:

[0136] The third calculation unit is used to calculate the ratio of the current change to the normal current of the target battery cell, and determine it as the sensitivity of the target battery cell.

[0137] Specifically, the formula for the current change in the second calculation unit is expressed as:

[0138]

[0139] Wherein, ΔI represents the current change, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of battery cells, and I represents the total current of the target parallel unit.

[0140] It should be noted that, when the target cell is a cell monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell tends to increase; if the target cell has an internal resistance increase fault, the current of the target cell tends to decrease; or,

[0141] In the case where the target cell is a cell not monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell tends to decrease, and if the target cell has an internal resistance increase fault, the current of the target cell tends to increase.

[0142] Optionally, the device further comprises:

[0143] A third acquisition unit, configured to acquire the monitoring quantity of the monitoring cells of the target parallel unit through a sensor;

[0144] a fourth calculation unit, configured to determine a monitoring current percentage according to a ratio of the monitoring quantity to the number of battery cells;

[0145] A fifth calculation unit is used to determine the sensitivity of the target battery cell according to the monitored current percentage and the current change.

[0146] Specifically, the formula for determining the sensitivity of the target battery cell in the fifth calculation unit is expressed as:

[0147]

[0148] Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of the battery cells, and y represents the percentage of the monitored current.

[0149] Specifically, the formula for determining the sensitivity of the target battery cell in the fifth calculation unit is expressed as:

[0150]

[0151] Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, and n represents the number of the battery cells.

[0152] Optionally, the device further comprises:

[0153] A monitoring module, used for monitoring the charge state of the target battery cell when the target battery cell of the target parallel unit of the battery module is not faulty;

[0154] The second sending module is used to send a thermal runaway warning signal to the battery system if the charge state of the target battery cell is inconsistent with self-discharge.

[0155] The embodiment of the present application also provides a readable storage medium, on which a program is stored, and when the program is executed by a processor, each process of the battery module early warning control method embodiment described above is implemented, and the same technical effect can be achieved. To avoid repetition, it is not repeated here. Among them, the readable storage medium, such as a read-only memory (Read-Only Memory, referred to as ROM), a random access memory (Random Access Memory, referred to as RAM), a disk or an optical disk, etc.

[0156] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0157] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary personnel in this technical field, several improvements and modifications can be made without departing from the principles described in the present invention. These improvements and modifications are also within the scope of protection of the present invention.

Claims

1. A battery module early warning control method, characterized in that: Applicable to a battery module comprising at least two groups of parallel-connected cells, comprising: Obtaining the current change of the target parallel unit of the battery module and the normal parallel unit adjacent to the target parallel unit, including: obtaining the total current of the target parallel unit and the number of cells of the target parallel unit; determining the current of the target cell of the target parallel unit according to the total current of the target parallel unit and the number of cells; obtaining the current of the normal cell of the normal parallel unit; calculating the difference between the current of the target cell and the current of the normal cell, and determining it as the current change; wherein the position of the normal cell is in a corresponding relationship with the position of the target cell; before obtaining the target total current of the normal parallel unit, at least one current sensor has been added to each parallel unit of the battery module; According to the current change, the sensitivity of the target battery cell of the target parallel unit is determined, including: calculating the ratio of the current change to the normal current of the target battery cell of the target parallel unit, and determining it as the sensitivity of the target battery cell of the target parallel unit, and the formula of the current change is expressed as: ;in, is represented by the current change, x is represented by the abnormal internal resistance factor of the abnormal battery cell, n is represented by the number of battery cells, and I is represented by the total current of the target parallel unit; If the sensitivity is within a first preset range, sending a fault degree signal to the battery system; Wherein, the method further comprises: In the case where the target cell is a cell monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell tends to increase; if the target cell has an internal resistance increase fault, the current of the target cell tends to decrease; or, In the case where the target cell is a cell not monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell shows a decreasing trend; if the target cell has an internal resistance increase fault, the current of the target cell shows an increasing trend; When the abnormal internal resistance factor x of the abnormal battery cell is 1, the sensitivity does not change with the number of battery cells.

2. The battery module early warning control method according to claim 1, characterized in that: The method further comprises: Obtaining the target total current of the normal parallel unit and the number of cells of the normal parallel unit; The ratio of the target total current to the number of second battery cells of the normal parallel unit is calculated, and the current of each normal battery cell of the normal parallel unit is determined.

3. The battery module early warning control method according to claim 2, characterized in that: The method further comprises: Acquire the monitoring quantity of the monitoring cells of the target parallel unit through a sensor; Determining a monitoring current percentage according to a ratio of the monitoring quantity to the number of battery cells; The sensitivity of the target battery cell is determined according to the monitored current percentage and the current change.

4. The battery module early warning control method according to claim 3, characterized in that: When the monitoring cell includes the target cell, the formula for determining the sensitivity of the target cell is expressed as: -1)*100%； Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, n represents the number of the battery cells, and y represents the percentage of the monitored current.

5. The battery module early warning control method according to claim 3, characterized in that: When the monitoring cell does not include the target cell, the formula for determining the sensitivity of the target cell is expressed as: -1)*100%； Wherein, S represents the sensitivity of the target battery cell, x represents the abnormal internal resistance factor of the abnormal battery cell, and n represents the number of the battery cells.

6. The battery module early warning control method according to claim 1, characterized in that: The method further comprises: When the target battery cell of the target parallel unit of the battery module is not faulty, monitoring the charge state of the target battery cell; If the charge state of the target battery cell is inconsistent with self-discharge, a thermal runaway warning signal is sent to the battery system.

7. A battery module early warning control device, characterized in that: Applicable to a battery module comprising at least two groups of parallel-connected cells, comprising: An acquisition module, used for acquiring the current variation of the target parallel unit of the battery module and the normal parallel unit adjacent to the target parallel unit; the acquisition module includes: a first acquisition unit, used for acquiring the total current of the target parallel unit and the number of cells of the target parallel unit; a first calculation unit, used for determining the current of the target cell of the target parallel unit according to the total current of the target parallel unit and the number of cells; a second acquisition unit, used for acquiring the current of the normal cell of the normal parallel unit; a second calculation unit, used for calculating the difference between the current of the target cell and the current of the normal cell, and determining it as the current variation; wherein the position of the normal cell corresponds to the position of the target cell; before acquiring the target total current of the normal parallel unit, at least one current sensor has been added to each parallel unit of the battery module; A first determination module is used to determine the sensitivity of the target battery cell of the target parallel unit according to the current change; the first determination module includes: a third calculation unit, which is used to calculate the ratio of the current change to the normal current of the target battery cell of the target parallel unit, and determine it as the sensitivity of the target battery cell of the target parallel unit; the formula of the current change in the second calculation unit is expressed as: ;in, is represented by the current change, x is represented by the abnormal internal resistance factor of the abnormal battery cell, n is represented by the number of battery cells, and I is represented by the total current of the target parallel unit; a sending module, configured to send a fault degree signal to the battery system if the sensitivity is within a first preset range; Wherein, in the case where the target battery cell is a battery cell monitored by a sensor, if the target battery cell has an internal resistance reduction fault, the current of the target battery cell shows an increasing trend; if the target battery cell has an internal resistance increase fault, the current of the target battery cell shows a decreasing trend; or, In the case where the target cell is a cell not monitored by a sensor, if the target cell has an internal resistance reduction fault, the current of the target cell shows a decreasing trend; if the target cell has an internal resistance increase fault, the current of the target cell shows an increasing trend; When the abnormal internal resistance factor x of the abnormal battery cell is 1, the sensitivity does not change with the number of battery cells.

8. A readable storage medium, characterized in that: The readable storage medium stores a program, and when the program is executed by the processor, the steps of the battery module early warning control method according to any one of claims 1 to 6 are implemented.

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