Internal resistance evaluation device and battery system

Abstract

A battery system can include a plurality of battery packs, each of the plurality of battery packs including a plurality of battery banks, and a battery management system that calculates a plurality of internal resistance (DCIR) values for the plurality of battery banks in each of the plurality of battery packs, performs a correction on a first internal resistance value related to a battery bank at a predetermined first location in each battery pack, and diagnoses whether the battery bank at the first location is abnormal based on the corrected first internal resistance value. Each of the plurality of battery banks can include a plurality of battery cells connected in parallel, and the first location is a same location in each of the plurality of battery packs.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2022-0057069, filed with the Korean Intellectual Property Office on May 10, 2022, the entire contents of which are incorporated herein by reference.

[0003] This disclosure relates to an internal resistance evaluation device and a battery system that uses information derived from the internal resistance evaluation device. Background Technology

[0004] A battery pack consists of multiple battery cells connected in series, parallel, or a series-parallel combination. In this case, due to the multiple contact resistances and coupling resistances within the battery cells, a voltage higher than the cell voltage of each individual battery cell is measured as the cell voltage of that cell when current flows through the battery pack. In other words, the measurement of the cell voltage of each battery cell is affected not only by the internal resistance of the corresponding cell but also by the mechanical resistance of the coupling components used to connect the multiple battery cells.

[0005] This presents a problem of difficulty in accurately measuring cell voltage. Cell voltage is crucial data for monitoring the state of battery cells, such as charging, overvoltage, and undervoltage. Summary of the Invention

[0006] Technical issues

[0007] In order to solve the above-mentioned problems in the related technologies, this disclosure attempts to provide an internal resistance evaluation device and a battery system using information derived from the internal resistance evaluation device, the internal resistance evaluation device being implemented to accurately measure the internal resistance values ​​of multiple battery cells.

[0008] Technical solution

[0009] A battery system according to the features of the present invention may include: a plurality of battery packs, each of the plurality of battery packs including a plurality of battery cells; and a battery management system that calculates a plurality of internal resistance (DCIR) values ​​for the plurality of battery cells in each of the plurality of battery packs, performs correction on a first internal resistance value associated with a battery cell at a predetermined first location in each of the plurality of battery packs, and diagnoses whether the battery cell at the first location is abnormal based on the corrected first internal resistance value. Each of the plurality of battery cells may include a plurality of battery cells connected in parallel, and the first location is the same location in each of the plurality of battery packs.

[0010] The battery management system can correct the first internal resistance value by multiplying the first internal resistance value by a predetermined ratio less than 1.

[0011] The predetermined ratio can be determined based on the result obtained by dividing the internal resistance of the battery cell at the first position in each battery pack by the median of the internal resistance of the multiple battery cells constituting the corresponding battery pack.

[0012] The battery system may further include: multiple monitoring ICs connected to multiple battery packs and measuring multiple battery cell voltages of multiple battery cells; and a main control IC that, for each of the multiple battery packs, calculates multiple internal resistance values ​​of multiple battery cells of each battery pack based on multiple battery cell voltages and current flowing in each battery cell, and corrects the internal resistance value of the battery cell at a first location based on a predetermined ratio.

[0013] The main control IC can correct the internal resistance value of the battery bank at the first position by multiplying the internal resistance value of the battery bank at the first position by a predetermined ratio, and the predetermined ratio can be less than 1.

[0014] The predetermined ratio can be determined based on the result obtained by dividing the internal resistance of the battery cell at the first position in each battery pack by the median of the internal resistance of the multiple battery cells constituting the corresponding battery pack.

[0015] Within each battery pack, the internal resistance of the battery cell at the first location may be more affected by mechanical resistance compared to the battery cells at other locations within the same battery pack.

[0016] For all battery packs in multiple battery packs, multiple internal resistance values ​​can be classified according to multiple battery cell locations, and the location of the battery cell corresponding to the multiple internal resistance values ​​that are determined to be outside the normal range can be determined as the first location.

[0017] An internal resistance assessment apparatus according to another feature of the present invention may include: a regularity verification unit that verifies the regularity of multiple internal resistance values ​​of multiple battery banks constituting each battery pack for multiple battery packs; a control chart analysis unit that determines a first position of a battery bank corresponding to multiple internal resistance values ​​determined to be out of normal range for each of multiple battery bank positions in all battery packs of the multiple battery packs; and an internal resistance analysis unit that determines the degree of correction based on the internal resistance value of the battery bank at the first position and the internal resistance values ​​of the multiple battery banks constituting each battery pack.

[0018] The internal resistance analysis unit can calculate a first value for each of the multiple battery packs by dividing the internal resistance of the battery pack at the first location by the median of the internal resistances of the multiple battery packs that make up each battery pack, and determine the degree of correction based on the average of the multiple first values ​​for all battery packs in the multiple battery packs.

[0019] The internal resistance analysis unit can determine the correction level by subtracting 1 from the average of multiple first values.

[0020] The regularity verification unit can verify the regularity of multiple internal resistances at each battery bank location for all battery banks in multiple battery packs.

[0021] Beneficial effects

[0022] The present invention provides an internal resistance evaluation device and a battery system using information derived from the internal resistance evaluation device, the internal resistance evaluation device being implemented to accurately measure the internal resistance values ​​of multiple battery cells. Attached Figure Description

[0023] Figure 1 This is a diagram illustrating an internal resistance evaluation apparatus according to an exemplary embodiment.

[0024] Figure 2 It is a probability plot showing the reference value distribution of the internal resistance of multiple battery cells in multiple battery packs.

[0025] Figure 3 This is a circuit diagram illustrating a battery pack according to an exemplary embodiment.

[0026] Figure 4 It is a graph showing the Xbar-S control plot related to the average value of the internal resistance.

[0027] Figure 5 The standard deviations associated with multiple battery libraries of 207 battery packs are shown, along with the results obtained by dividing the standard deviations by the median (the ratio of standard deviation to median).

[0028] Figure 6 The standard deviations associated with multiple battery banks in a 207-cell battery pack are shown when the internal resistance of the battery bank located at the eighth position with a large internal resistance value is corrected, along with the results obtained by dividing the standard deviations by the median.

[0029] Figure 7 It shows the basis Figure 5 The results of the handling power analysis are shown as the ratio of standard deviation to median.

[0030] Figure 8 It shows the basis Figure 6 The results of the handling power analysis are shown as the ratio of standard deviation to median.

[0031] Figure 9 This is a diagram illustrating a battery system according to an exemplary embodiment.

[0032] Figure 10 This is a diagram illustrating a battery pack according to an exemplary embodiment. Detailed Implementation

[0033] This invention can relate to a battery system comprising multiple battery packs, each battery pack including multiple battery cells electrically connected. Each battery pack may include multiple battery cells connected in series, or may include multiple battery banks, each battery bank consisting of at least two battery cells connected in parallel.

[0034] In the following description, exemplary embodiments disclosed herein will be described in detail with reference to the accompanying drawings; however, identical or similar components are indicated by identical or similar reference numerals and will not be described again. As used herein, the suffixes “module” and / or “unit” for constituent elements are given only for ease of preparation of this specification and are used interchangeably, and the suffixes themselves do not have a distinguishing meaning or function from one another. Furthermore, when describing exemplary embodiments disclosed herein, detailed descriptions of well-known technologies will be omitted if it is determined that such detailed descriptions may obscure the essential points of the exemplary embodiments disclosed herein. Moreover, the accompanying drawings are provided to aid in the easy understanding of the exemplary embodiments disclosed herein, and the technical spirit disclosed herein is not limited to the drawings; it should be understood that the invention includes all modifications, equivalents, and substitutions included within the spirit and scope of the invention.

[0035] Terms including ordinal numbers such as first and second are used to describe various constituent elements, but constituent elements are not limited by these terms. These terms are only used to distinguish one constituent element from another.

[0036] In this application, it should be understood that the terms "comprising" and "having" are intended to specify the presence of the features, numbers, steps, operations, constituent elements and components or combinations thereof described in the specification, without excluding the possibility of the presence or addition of one or more other features, numbers, steps, operations, constituent elements and components or combinations thereof.

[0037] In the component for controlling other components under specific control conditions according to the exemplary embodiment, a program implemented as a set of commands specifying the control algorithm required to control the other components may be installed. The control component can generate output data by processing input data and stored data according to the installed program. The control component may include non-volatile memory for storing the program and memory for storing the data.

[0038] In multiple battery packs with identical structures, the internal resistance of a particular cell or battery bank may be higher than that of other cells or batteries. Depending on the location of individual cells or batteries within each battery pack, the type, number, and shape of the coupling components (e.g., busbars, wiring, etc.) connected to each cell or battery bank may differ. Contact resistance, coupling resistance, etc., may arise due to these coupling components, and will be referred to hereinafter as mechanical resistance. Among the multiple internal resistances of multiple batteries, the resistance value of the internal resistance most significantly affected by mechanical resistance may be greater than that of the internal resistance least significantly affected.

[0039] A regularity verification method according to an exemplary embodiment may include: the steps of obtaining the internal resistance distribution of multiple battery cells or multiple battery banks at each location in a plurality of battery packs; the steps of comparing the internal resistance distributions associated with all locations with each other; and the steps of determining, based on the comparison results, locations that are outside the normal range defined by internal resistance distributions that are different from the internal resistance distributions at all locations.

[0040] A battery system according to an exemplary embodiment can use the battery cell voltage and current or the battery bank voltage and current to compensate for the calculated internal resistance when determining the internal resistance associated with a battery cell or battery bank at a location obtained through a regularity verification method.

[0041] The following description will provide an internal resistance correction method and a battery system using the internal resistance correction method, which can reduce the effects of mechanical resistance by analyzing the internal resistance values ​​of multiple battery cells in a structure comprising multiple battery cells connected in series in each battery pack.

[0042] Figure 1 This is a diagram illustrating an internal resistance evaluation apparatus according to an exemplary embodiment.

[0043] like Figure 1 As shown, the internal resistance assessment device 500 includes a regularity verification unit 510, a control chart analysis unit 520, and an internal resistance analysis unit 530.

[0044] Figure 2 It is a probability graph showing the distribution of internal resistance values ​​of multiple battery cells in multiple battery packs.

[0045] Figure 3 This is a circuit diagram illustrating a battery pack according to an exemplary embodiment.

[0046] like Figure 3As shown, battery pack 1 may include fourteen battery cells 1_1 to 1_14 connected in series. Each of the fourteen battery cells 1_1 to 1_14 includes two battery cells, cell 1 and cell 2, connected in parallel. The fourteen battery cells 1_1 to 1_14 are connected in series between the anode terminal BP+ and the cathode terminal BP- of battery pack 1. Although in Figure 3 The diagram shows that battery pack 1 includes fourteen battery cells and each battery cell includes two battery cells, but the number of battery cells constituting the battery pack may be different from 14, and each battery cell may include three or more battery cells connected in parallel.

[0047] exist Figure 2 The probability diagram uses data on the internal resistance values ​​DCIR1 to DCIR14 of fourteen cell banks in each of the 207 battery packs (hereinafter referred to as input data). The input data can be measured directly or calculated by dividing the voltage change of each cell bank by the current flowing in the corresponding cell bank. Each of the fourteen cell banks can be distinguished by its corresponding position. The position of each cell bank in the multiple cell banks connected in series between the anode and cathode terminals in the battery pack refers to its relative position. For example, in battery pack 1, positions one through fourteen can be defined along the direction from anode terminal BP+ to cathode terminal BP-, or conversely, positions one through fourteen can be defined along the direction from cathode terminal BP- to anode terminal BP+.

[0048] Figure 2 The horizontal axis represents the internal resistance value, and the vertical axis represents the probability of the number of battery banks with internal resistance values ​​at the same location in the 207 battery packs. For example, if the probability is PA% when the DCIR1 of the battery bank at the first location (e.g., reference numeral "1_1") is a specific value RA (Ω), then the probability of the battery bank at the first location in the total 207 battery packs ( Figure 3 The number of battery banks with an internal resistance value of RA (Ω) in the attached figure (labeled "1_1") can be 207. PA / 100.

[0049] like Figure 2 As shown, the internal resistances DCIR1 to DCIR7 and DCIR9 to DCIR14 of thirteen of the fourteen battery cells in each of the 207 battery packs are distributed in region 1. However, the internal resistance DCIR8 of the eighth battery cell is distributed in region 2, which is different from region 1.

[0050] The regularity verification unit 510 can verify the regularity of the input data. Specifically, the regularity verification unit 510 can calculate P-values ​​related to the internal resistance values ​​DCIR1 to DCIR14, and verify regularity based on determining whether each calculated P-value is equal to or less than a predetermined reference value. Figure 3 All P-values ​​related to the internal resistance values ​​DCIR1 to DCIR14 of the fourteen battery banks in the 207 battery packs shown are equal to or less than 0.05. Therefore, it can be seen that the internal resistance values ​​of the fourteen battery banks in the 207 battery packs are normal. If the normality verification is complete, the control chart of the internal resistance values ​​of the fourteen battery banks in the 207 battery packs can be analyzed. When the normality verification of the input data is completed, the normality verification unit 510 can send it to the control chart analysis unit 520.

[0051] The control chart analysis unit 520 can calculate statistical values ​​related to the internal resistance values ​​of multiple battery banks for multiple battery packs, as shown in Table 1. The statistical values ​​include the mean (Avg), median (med), minimum (min), maximum (max), standard deviation (std), and the ratio of standard deviation to median (std / med).

[0052] [Table 1]

[0053]

[0054] The control chart analysis unit 520 can deduce that among the internal resistance values ​​DCIR1 to DCIR14, resistance value DCIR8 is greater than other resistance values ​​DCIR, as shown in Table 1. For example, in a battery pack of 207 cells, the battery cell at the eighth position (e.g., Figure 3 The average (Avg), median (med), minimum (min), and maximum (max) internal resistance values ​​of DCIR8 (as shown in Figures 1-8) are greater than those of the battery bank at other locations (e.g., Figure 3 The control chart analysis unit 520 can notify the internal resistance analysis unit 530 that the internal resistance values ​​DCIR1 to DCIR7 and DCIR9 to DCIR14 (labeled "1_1" to "1_7" and "1_9" to "1_14") are average (Avg), median (med), minimum (min), and maximum (max).

[0055] Figure 4 It is a graph showing the Xbar-S control plot related to the average value of the internal resistance.

[0056] exist Figure 4 The figure shows the average values ​​related to the internal resistance of 14 battery banks for 207 battery packs. Figure 4In the diagram, the x-axis represents the positions of the 14 battery cells, with values ​​ranging from the first to the fourteenth position. The y-axis represents the average value associated with the internal resistance values ​​DCIR1 to DCIR14 of the 14 battery cells, with values ​​representing the resistance values ​​of the internal resistance. The control chart analysis unit 520 can infer that the average value of DCIR8 is larger than the other DCIR values ​​and exceeds the upper limit UCL of the control chart. Figure 4 As shown.

[0057] The internal resistance analysis unit 530 can calculate the average (Avg), median (med), minimum (min), maximum (max), standard deviation (std), and the ratio of standard deviation to median (std / med) of the internal resistance values ​​for all battery banks in the 207 battery packs, as shown in Table 2.

[0058] [Table 2]

[0059]

[0060] The internal resistance analysis unit 530 can calculate the average (Avg), median (med), minimum (min), and maximum (max) values ​​related to the internal resistance values ​​of the fourteen battery banks in each of the 207 battery banks, as shown in Table 3.

[0061] [Table 3]

[0062]

[0063] The internal resistance analysis unit 530 can perform the operation of calculating the average internal resistance value of the fourteen battery banks constituting a battery bank for all 207 battery banks (hereinafter referred to as the average internal resistance of the battery bank). Then, the average internal resistance of the 207 battery banks is calculated, and in Table 3 above, the row defined by "Avg" on the vertical axis represents the statistical value related to the average internal resistance of the 207 battery banks. In other words, "3.856" is the average (Avg) of the average internal resistance of the 207 group units, "3.842" is the median (med) of the average internal resistance of the 207 group units, "3.798" is the minimum (min) of the average internal resistance of the 207 group units, "4.078" is the maximum (max) of the average internal resistance of the 207 group units, "0.066" is the standard deviation (std) of the average internal resistance of the 207 group units, and "0.017" is the ratio (std / med) of the standard deviation (std) to the median (med) of the average internal resistance of the 207 group units.

[0064] The internal resistance analysis unit 530 can perform the operation of calculating the median internal resistance value of the fourteen battery banks constituting a battery bank (hereinafter referred to as the median internal resistance of the battery bank) for all 207 battery banks. Then, the median internal resistance of the 207 battery banks is calculated, and in Table 3 above, the row on the vertical axis defined by "med" represents the statistical values ​​related to the median internal resistance of the 207 battery banks. In other words, "3.859" is the average (Avg) of the median internal resistance of the 207 group units, "3.840" is the median (med) of the median internal resistance of the 207 group units, "3.805" is the minimum (min) of the median internal resistance of the 207 group units, "4.081" is the maximum (max) of the median internal resistance of the 207 group units, "0.066" is the standard deviation (std) of the median internal resistance of the 207 group units, and "0.017" is the ratio (std / med) of the standard deviation (std) of the median internal resistance of the 207 group units.

[0065] The internal resistance analysis unit 530 can perform the operation of calculating the minimum internal resistance value (hereinafter referred to as the minimum internal resistance of the cell bank) of the fourteen cell banks constituting a cell bank for all 207 cell banks. Then, the minimum internal resistance of the 207 cell banks is calculated, and in Table 3 above, the row on the vertical axis defined by "min" represents the statistical values ​​related to the minimum internal resistance of the 207 cell banks. In other words, "3.590" is the average (Avg) of the minimum internal resistance of the 207 group units, "3.580" is the median (med) of the minimum internal resistance of the 207 group units, "3.540" is the minimum (min) of the minimum internal resistance of the 207 group units, "3.793" is the maximum (max) of the minimum internal resistance of the 207 group units, "0.042" is the standard deviation (std) of the minimum internal resistance of the 207 group units, and "0.011" is the ratio (std / med) of the standard deviation (std) of the minimum internal resistance of the 207 group units to the median (med).

[0066] The internal resistance analysis unit 530 can perform the operation of calculating the maximum internal resistance value (hereinafter referred to as the maximum internal resistance value of the fourteen battery cells constituting a battery cell) for all 207 battery cells. Then, the maximum internal resistance value of the 207 battery cells is calculated, and in Table 3 above, the row defined by "max" on the vertical axis represents the statistical values ​​related to the maximum internal resistance value of the 207 battery cells. In other words, "4.122" is the average (Avg) of the maximum internal resistance of the 207 group units, "4.115" is the median (med) of the maximum internal resistance of the 207 group units, "4.023" is the minimum (min) of the maximum internal resistance of the 207 group units, "4.334" is the maximum (max) of the maximum internal resistance of the 207 group units, "0.089" is the standard deviation (std) of the maximum internal resistance of the 207 group units, and "0.024" is the ratio (std / med) of the standard deviation (std) to the median (med) of the maximum internal resistance of the 207 group units.

[0067] The internal resistance analysis unit 530 can perform the following operation: divide the internal resistance value of the battery cell at the eighth position in a battery pack by the median of the internal resistance values ​​of the fourteen battery cells constituting the corresponding battery pack, to calculate the ratio of the internal resistance value of the battery cell at the eighth position to the median of the internal resistance of the cell cells in the pack for all 207 battery packs (hereinafter referred to as the resistance ratio value). Then, 207 resistance ratio values ​​are calculated, and Table 4 is a table showing the average, median, minimum, maximum, standard deviation, and the ratio of the standard deviation to the median value associated with the 207 resistance ratio values.

[0068] [Table 4]

[0069]

[0070] As shown in Table 4, the average resistance ratio of the battery cell at position 8 out of 207 battery packs was measured to be 1.062, which is 6.2% higher than the median. In Table 3, since the ratio of the standard deviation of the average internal resistance of the battery cells in the group to the median (std / med) is 1.7%, it can be interpreted that the average standard dispersion of the battery cells in the 207 battery packs is 1.7%. Therefore, it can be seen that the internal resistance of the battery cell at position 8 is greater than that of the battery cells at other positions. This can be interpreted as the internal resistance of the battery cell at position 8 being more affected by mechanical resistance compared to the battery cells at other positions. In this case, the internal resistance analysis unit 530 can determine 6.2% as the correction level for the internal resistance value of the battery cell at position 8. Then, to correct the internal resistance value of the battery cell at position 8, the internal resistance value can be multiplied by 93.8% (100% - 6.2%).

[0071] Figure 5The standard deviations associated with multiple battery libraries of 207 battery packs are shown, along with the results obtained by dividing the standard deviations by the median (the ratio of standard deviation to median).

[0072] Figure 6 The standard deviations associated with multiple battery banks in a 207-cell battery pack are shown when the internal resistance of the battery bank located at the eighth position with a large internal resistance value is corrected, along with the results obtained by dividing the standard deviations by the median.

[0073] As from Figure 5 and Figure 6 The comparison shows that the standard deviation and scattering mean of multiple battery libraries of 207 battery packs have decreased by 65% ​​compared to the previous data.

[0074] Figure 7 It shows the basis Figure 5 The results of the handling power analysis are shown as the ratio of standard deviation to median.

[0075] Figure 8 It shows the basis Figure 6 The results of the handling power analysis are shown as the ratio of standard deviation to median.

[0076] exist Figure 7 The table shows that most of the ratios of the standard deviation to the median associated with the 207 battery packs are greater than the upper limit of the specification, which is 0.01.

[0077] On the other hand, Figure 8 The table shows that most of the ratios of the standard deviation to the median associated with the 207 battery packs are less than the upper limit of the specification, which is less than 0.01.

[0078] Additionally, as from Figure 7 and Figure 8 The analysis results of the processing capacity shown indicate that the processing capacity has also been improved.

[0079] As described above, an accurate internal resistance value can be determined by identifying a battery cell with a larger internal resistance value than other battery cells and correcting the internal resistance value of the corresponding battery cell. This is used in the battery system described below. According to an exemplary embodiment, the battery system can remove the influence of mechanical resistance from the calculated internal resistance value when using information about a specific battery cell with a large internal resistance value to determine the internal resistance of a battery cell at a particular location.

[0080] Figure 9 This is a diagram illustrating a battery system according to an exemplary embodiment.

[0081] exist Figure 9In this configuration, battery system 2 includes multiple battery packs 10_1 to 10_n (where n is a natural number of 2 or greater) and battery management system 20. Battery management system 20 may include multiple monitoring ICs 30_1 to 30_n respectively connected to the multiple battery packs 10_1 to 10_n, and a main control IC 40. Battery system 2 may also include a first main relay 51 connected between output terminal P+ and the anode of battery pack 10_1, and a second main relay 52 connected between output terminal P- and the cathode of battery pack 10_n.

[0082] The first main relay 51 and the second main relay 52 can be switched under the control of the battery management system 20. For example, the main control IC 40 can generate switching signals SC1 and SC2 for controlling the switching operation of the first main relay 51 and the second main relay 52, and supply them to the first main relay 51 and the second main relay 52. ​​Although in Figure 9 Two main relays are shown, but the invention is not limited thereto. For example, in battery system 2, a pre-charge relay and a pre-charge resistor may be connected in parallel with one of the two main relays. Alternatively, battery system 2 may include only one of the two main relays.

[0083] An external device 3 can be connected between the output terminal P+ and the output terminal P-. The external device 3 can be a charger for supplying power from the multiple battery packs 10_1 to 10_n through the discharge of the multiple battery packs 10_1 to 10_n to an external load (e.g., a motor for supplying driving force to an electric vehicle) or for supplying power from an external commercial power source for charging the multiple battery packs 10_1 to 10_n.

[0084] Figure 10 This is a diagram illustrating a battery pack according to an exemplary embodiment.

[0085] exist Figure 10 The diagram shows battery pack 10_i as one of a plurality of battery packs 10_1 to 10_n. 'i' can be one of the natural numbers from 1 to n.

[0086] Each of the plurality of battery packs 10_1 to 10_n comprises a plurality of battery libraries 100_1 to 100_m connected in series (where m is a natural number of 2 or greater). Each of the plurality of battery libraries 100_1 to 100_m comprises two battery cells connected in parallel (e.g., reference numerals 101 and 102). Although in Figure 10The diagram shows that each of the plurality of battery cells 100_1 to 100_m consists of two cells, but the invention is not limited thereto. Each of the plurality of battery cells 100_1 to 100_m may include three or more battery cells connected in parallel. In the plurality of battery packs 10_1 to 10_n, other battery packs may also be configured similarly. Figure 10 It is implemented as shown in battery pack 10_i.

[0087] The battery management system 20 can be connected to multiple battery packs 10_1 to 10_n and measures the cell voltage at predetermined monitoring cycles. The cell voltage is the voltage of multiple cell banks in each of the multiple battery packs 10_1 to 10_n.

[0088] Each of the multiple monitoring ICs 30_1 to 30_n can be connected to two terminals of each battery cell in a corresponding battery pack and measures the cell voltage of each battery cell. Each of the multiple monitoring ICs 30_1 to 30_n can send multiple measured cell voltages to the main control IC 40. For example, as Figure 10 As shown, monitoring IC 30_i is connected to two terminals of each of the multiple battery banks 100_1 to 100_m in battery pack 10_i. Each of the multiple monitoring ICs 30_1 to 30_n can receive the voltage of each of the anode and cathode of each of the multiple battery banks in the corresponding battery pack, and measure the bank voltage of each battery bank based on the difference between the anode voltage and the cathode voltage. For example, monitoring IC 30_i can send the multiple bank voltages BV1 to BVm of the multiple battery banks 100_1 to 100_m to the main control IC 40.

[0089] The battery management system 20 can obtain information about the current and temperature of multiple battery packs 10_1 to 10_n (hereinafter referred to as battery pack current and battery pack temperature).

[0090] The current sensor 60 measures the battery pack current IB and sends information about the measured battery pack current IS to the main control IC 40. The main control IC 40 can determine the temperature of each cell based on the temperature of the battery pack, which includes each cell.

[0091] Multiple temperature sensors 70_1 to 70_n can measure the temperature of the battery pack where the temperature sensor is located, and send information items TS_1 to TS_n about the temperature of each battery pack to the main control IC 40.

[0092] The battery management system 20 can control multiple battery banks in each of the multiple battery packs 10_1 to 10_n and perform cell balancing on them based on multiple bank voltages. The battery management system 20 can estimate the SOC (State of Charge), SOH (State of Health), SOP (State of Power), etc., of each of the multiple battery packs 10_1 to 10_n based on the multiple bank voltages and measurement information about each battery pack (e.g., battery pack current, battery pack temperature, etc.).

[0093] The battery management system 20 can calculate the internal resistance (DCIR) values ​​of multiple battery cells in each of the multiple battery packs 10_1 to 10_n, and perform corrections on the internal resistance values ​​of specific battery cells.

[0094] For example, the main control IC 40 can be used Figure 10 The internal resistance of each battery bank is calculated by measuring the voltage change of the bank voltage and the current flowing in each bank among the multiple battery banks 100_1 to 100_m shown. In an exemplary embodiment, since the multiple battery packs 10_1 to 10_n are connected in series, the current flowing in each bank can be the same as the battery pack current IB. The voltage change of each bank voltage can be due to the voltage change caused by charging or discharging of battery pack 10_i. The main control IC 40 can measure the voltage of the battery bank (hereinafter referred to as the post-charging battery bank voltage) after a predetermined time has elapsed from the start of charging, and calculate the internal resistance based on the result obtained by dividing the voltage difference between the pre-charging and post-charging battery bank voltages by the battery bank current during the charging period. Alternatively, the main control IC 40 can measure the battery bank voltage (hereinafter referred to as the post-discharge battery bank voltage) after a predetermined time has elapsed since the end of discharge, and calculate the internal resistance value based on the result obtained by dividing the voltage difference between the lowest battery bank voltage during discharge and the post-discharge battery bank voltage by the battery bank current during the discharge period. In this case, charging and discharging can be performed with constant charging and discharging currents. Furthermore, when determining the internal resistance value of each battery bank, the main control IC 40 can take into account the effects of the temperature or charge rate (C-rate) of each bank during charging and discharging.

[0095] The method for calculating the internal resistance of each of the multiple battery banks 100_1 to 100_m is not limited to the method described above, and can be derived from known methods for calculating the internal resistance of battery cells. For example, the main control IC 40 can calculate the internal resistance value of each battery cell (e.g., reference numerals 101 and 102) constituting each of the multiple battery banks 100_1 to 100_m using known methods, and calculate the parallel resistance associated with the two calculated internal resistances, thereby calculating the internal resistance of each battery bank.

[0096] The main control IC 40 calibrates the internal resistance of battery cells at specific locations within a plurality of battery packs 10_1 to 10_n. A battery cell at a specific location (hereinafter referred to as a high-resistance battery cell) is a battery cell within the plurality of battery packs 10_1 to 10_n that has a higher internal resistance value than other battery cells due to the mechanical resistance as described above. The number of high-resistance battery cells in each of the plurality of battery packs 10_1 to 10_n can be one or more. The term "high-resistance battery cell" does not necessarily mean that the actual internal resistance of the corresponding battery cell is high, but may mean that the internal resistance value of the corresponding battery cell is measured to be higher than the actual internal resistance value due to the mechanical resistance.

[0097] The main control IC 40 can calculate multiple internal resistance values ​​associated with multiple battery banks 100_1 to 100_m, and perform correction on the internal resistance values ​​of the high-resistance battery banks. The main control IC 40 can store data required for correcting the internal resistance values ​​of the high-resistance battery banks, calculate the internal resistance values ​​of the high-resistance battery banks for multiple battery banks 10_1 to 10_n, and perform correction on the calculated internal resistance values. The data required for correcting the internal resistance values ​​of the high-resistance battery banks may include data about a correction function used to receive the calculated internal resistance values ​​and correct the internal resistance values, as well as parameters constituting the correction function. These parameters can be determined based on the ratio of the internal resistance value of the high-resistance battery bank to its median value.

[0098] For example, the average resistance ratio of the battery bank at the eighth position among the aforementioned 207 battery packs was measured to be 1.062, which is 6.2% higher than the median. In this case, the correction function is a function that multiplies the calculated internal resistance value by a predetermined correction ratio, and the correction ratio, which is a parameter of the correction function, can be determined by subtracting 6.2% from 100%, i.e., 93.8%. The main control IC 40 can calculate the internal resistance value of the high-resistance battery bank and compensate for the internal resistance value by multiplying the calculated internal resistance value by 93.8%.

[0099] The main control IC 40 can diagnose whether each battery cell is abnormal based on the internal resistance values ​​of multiple battery cells in each of the multiple battery packs 10_1 to 10_n. For example, the main control IC 40 can diagnose that a battery cell with a resistance value greater than a predetermined threshold among the multiple battery cells is abnormal.

[0100] While the invention has been described in conjunction with exemplary embodiments now considered practical, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A battery system, comprising: Multiple battery packs, each of the multiple battery packs comprising multiple battery cells; as well as A battery management system calculates multiple internal resistance values ​​for multiple battery cells in each of the plurality of battery packs, performs correction on a first internal resistance value associated with a battery cell at a predetermined first location in each battery pack, and diagnoses whether the battery cell at the first location is abnormal based on the corrected first internal resistance value, wherein... Each of the plurality of battery modules includes a plurality of battery cells connected in parallel, and the first position is the same position in each of the plurality of battery packs; The battery management system corrects the first internal resistance value by multiplying it by a predetermined ratio. The predetermined ratio is determined based on the result obtained by dividing the internal resistance value of the battery cell at the first location in each battery pack by the median of the internal resistance values ​​of the plurality of battery cells constituting the corresponding battery pack.

2. The battery system according to claim 1, wherein, The predetermined ratio is less than 1.

3. The battery system according to claim 1, further comprising: Multiple monitoring ICs are connected to the multiple battery packs and measure the voltage of multiple battery cells in the multiple battery cells; as well as A main control IC, for each of the plurality of battery packs, calculates a plurality of internal resistance values ​​of the plurality of battery cells in each battery pack based on the voltage of the plurality of battery cells and the current flowing in each battery cell, and corrects the internal resistance value of the battery cell at the first location based on the predetermined ratio.

4. The battery system according to claim 3, wherein, The main control IC corrects the internal resistance of the battery bank at the first location by multiplying the internal resistance of the battery bank at the first location by the predetermined ratio, and The predetermined ratio is less than 1.

5. The battery system according to claim 1, wherein, In each battery pack, the internal resistance of the battery cell at the first location is more affected by mechanical resistance compared to the battery cells at other locations in the corresponding battery pack, wherein the mechanical resistance is the contact resistance or coupling resistance caused by the coupling members connected to each battery cell or battery cell.

6. The battery system according to claim 1, wherein, For all battery packs in the plurality of battery packs, multiple internal resistance values ​​are classified according to multiple battery cell locations, and the location of the battery cell corresponding to the multiple internal resistance values ​​that are determined to be outside the normal range is determined as the first location.

7. An internal resistance evaluation device, comprising: A regularity verification unit verifies the regularity of multiple internal resistance values ​​for multiple battery banks constituting each battery pack for multiple battery packs. The control chart analysis unit classifies the multiple internal resistance values ​​according to multiple battery cell locations for all battery packs in the multiple battery packs, and determines the first location of the battery cell corresponding to the multiple internal resistance values ​​that are determined to be out of the normal range. as well as An internal resistance analysis unit determines the degree of correction based on the internal resistance value of the battery bank at the first location and the internal resistance values ​​of the plurality of battery banks constituting each battery pack; wherein the internal resistance analysis unit calculates a first value for each of the plurality of battery packs by dividing the internal resistance of the battery bank at the first location by the median of the internal resistances of the plurality of battery banks constituting each battery pack, and determines the degree of correction based on the average of the plurality of first values ​​for all battery packs in the plurality of battery packs.

8. The internal resistance evaluation device according to claim 7, wherein, The internal resistance analysis unit determines the correction level by subtracting 1 from the average of the plurality of first values.

9. The internal resistance evaluation device according to claim 7, wherein, The regularity verification unit verifies the regularity of multiple internal resistances at each battery bank location for all of the multiple battery packs.

Images