Battery management device, battery pack, battery system and battery management method

Abstract

A battery management device according to the present disclosure includes: a voltage measurement circuit that measures a cell voltage of each of a plurality of battery cells; and a control unit that determines the cell voltage of each of the plurality of battery cells and a reference voltage of the plurality of battery cells at preset time intervals during a rest period. The control unit determines a first cumulative change in the cell voltage of each battery cell during the rest period. The control unit determines a second cumulative change in the reference voltage during the rest period. The control unit determines whether each battery cell is defective by comparing the first cumulative change with the second cumulative change.

Description

Technical Field

[0001] The present disclosure relates to abnormality detection for battery cells.

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0096289 filed on July 31, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Background Art

[0003] Recently, the demand for portable electronic products such as laptop computers, camcorders, and mobile phones has rapidly increased, and with the widespread development of electric vehicles, energy storage batteries, robots, and satellites, much research has been conducted on rechargeable high-performance batteries.

[0004] Currently, commercial batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc., and among them, lithium batteries have almost no or no memory effect, so they are more popular than nickel-based batteries because they have the advantages of being able to be charged at any time when convenient, having a very low self-discharge rate and a high energy density.

[0005] Recently, with the widespread use of battery systems requiring high voltage (eg, energy storage systems, electric vehicles), there is an increasing need for diagnostic technology to accurately detect abnormalities in each of a plurality of battery cells connected in series in a battery pack.

[0006] When a battery cell instantaneously exhibits a large voltage drop exceeding a threshold, a defective battery cell is detected. However, when the voltage of a battery cell changes slowly, the abnormality of the battery cell cannot be accurately detected.

[0007] Meanwhile, polarization that occurs during battery charge / discharge gradually decreases during the rest period. Therefore, as polarization gradually decreases from the point in time when battery charge / discharge stops, the voltage of the resting battery gradually changes toward the open circuit voltage (OCV) corresponding to the battery's state of charge (SOC). However, depending on the cause of the abnormality, a voltage change much greater than the common voltage change due to reduced polarization may occur during the rest period. Summary of the Invention

[0008] Technical issues

[0009] The present disclosure is designed to solve the above-mentioned problems, and thus the present disclosure aims to provide a battery management device, a battery pack, a battery system, and a battery management method for detecting abnormality of each battery cell based on a voltage history of each battery cell of a plurality of battery cells.

[0010] These and other purposes and advantages of the present disclosure can be understood through the following description and become apparent according to the embodiments of the present disclosure.In addition, it is easy to understand that the purposes and advantages of the present disclosure can be achieved by the means given in the appended claims and their combinations.

[0011] Technical Solution

[0012] A battery management device according to the disclosed embodiment includes: a voltage measurement circuit configured to measure a cell voltage of each of a plurality of battery cells; and a control unit configured to determine the cell voltage of each of the plurality of battery cells and a reference voltage of the plurality of battery cells at preset time intervals during a rest period. The control unit is configured to determine a first cumulative change in the cell voltage of each of the battery cells during the rest period. The control unit is configured to determine a second cumulative change in the reference voltage during the rest period. The control unit is configured to determine whether each of the plurality of battery cells is defective by comparing the first cumulative change with the second cumulative change.

[0013] The control unit may be configured to determine the reference voltage to be equal to an average value or a median value of cell voltages of the plurality of battery cells.

[0014] The control unit may be configured to determine the first accumulated variation of each battery cell by accumulating a variation of the cell voltage of each battery cell at preset time intervals during the rest period.

[0015] The control unit may be configured to determine the second accumulated variation of the reference voltage by accumulating variations of the reference voltage at preset time intervals during the rest period.

[0016] The control unit may be configured to determine an abnormality history at preset time intervals during the rest period, the abnormality history indicating a temporal change in a difference between a first cumulative change and a second cumulative change for each battery cell. The control unit may be configured to determine whether each battery cell is defective based on a maximum value and a minimum value of the abnormality history associated with each battery cell.

[0017] The control unit may be configured to determine that each battery cell associated with an abnormality history in which a maximum value is greater than a first threshold value and a minimum value is less than a second threshold value, among the plurality of battery cells, is defective.

[0018] The control unit may be configured to determine that each battery cell among the plurality of battery cells associated with an abnormality history in which a maximum value is greater than a first threshold, a minimum value is less than a second threshold, and an absolute value of a slope between the maximum value and the minimum value is greater than a third threshold is defective.

[0019] A battery pack according to another aspect of the present disclosure includes a battery management device.

[0020] A battery system according to another aspect of the present disclosure includes a battery pack.

[0021] A battery management method according to another aspect of the present disclosure is performed at preset time intervals during a rest period of a plurality of battery cells. The battery management method includes: determining a cell voltage of each of the plurality of battery cells and a reference voltage of the plurality of battery cells; determining a first cumulative change in the cell voltage of each battery cell during the rest period; determining a second cumulative change in the reference voltage during the rest period; and determining whether each of the plurality of battery cells is defective by comparing the first cumulative change and the second cumulative change of each battery cell.

[0022] Determining whether each of a plurality of battery cells is defective may include determining an abnormality history at preset time intervals during a rest period, the abnormality history indicating a timing change in a difference between a first cumulative change and a second cumulative change of each battery cell, and determining whether each battery cell is defective based on a maximum value and a minimum value of the abnormality history associated with each battery cell.

[0023] Determining whether each of the plurality of battery cells is defective may include determining that each of the plurality of battery cells associated with an abnormality history in which a maximum value is greater than a first threshold and a minimum value is less than a second threshold is defective.

[0024] Determining whether each of the plurality of battery cells is defective may include determining that each of the plurality of battery cells that is associated with an abnormal history in which a maximum value is greater than a first threshold, a minimum value is less than a second threshold, and an absolute value of a slope between the maximum value and the minimum value is greater than a third threshold is defective.

[0025] Beneficial effects

[0026] According to at least one embodiment of the present disclosure, abnormality of each battery cell among a plurality of battery cells may be detected based on the voltage history of each battery cell.

[0027] Specifically, during a rest period, by periodically comparing the total change in cell voltage of each battery cell with the total change in reference voltage of multiple battery cells, a battery cell among multiple battery cells that exhibits voltage behavior that is significantly different from other battery cells can be determined to be defective.

[0028] The effects of the present disclosure are not limited to the above-described effects, and those skilled in the art can clearly understand these and other effects from the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the present disclosure set forth below, are used to provide a further understanding of the technical solutions of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the accompanying drawings.

[0030] Figure 1 is a schematic diagram exemplarily showing the configuration of a battery system according to the present disclosure.

[0031] Figure 2 is a graph referred to in describing a voltage history associated with each of a normal battery cell and a defective battery cell.

[0032] Figure 3 is a graph referred to when setting the cumulative change associated with each of the normal battery cells and the defective battery cells.

[0033] Figure 4 is a graph referred to when describing the abnormal history associated with a battery cell.

[0034] Figure 5 is a flowchart exemplarily illustrating a battery management method according to the first embodiment of the present disclosure.

[0035] Figure 6 is a flowchart exemplarily illustrating a battery management method according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted based on the meaning and concept corresponding to the technical solution of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms to obtain the best interpretation.

[0037] Therefore, the embodiments described herein and the descriptions shown in the accompanying drawings are only the most preferred embodiments of the present disclosure, but are not intended to fully describe the technical solutions of the present disclosure. Therefore, it should be understood that various other equivalents and modifications may be made thereto when submitting this application.

[0038] Terms including ordinal numbers such as first, second, etc. are used to distinguish one element from another among various elements, but are not intended to limit the elements by the terms.

[0039] Unless the context clearly indicates otherwise, it should be understood that the term "comprising" used in this specification specifies the presence of the elements described, but does not exclude the presence or addition of one or more other elements. In addition, the term "control unit" used herein refers to a processing unit having at least one function or operation, and this can be implemented by hardware and software alone or in combination.

[0040] Furthermore, throughout this specification, it will be further understood that when an element is referred to as being “connected to” another element, it can be directly connected to the other element or intervening elements may be present.

[0041] The preferred embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted based on the meaning and concept corresponding to the technical solution of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms to obtain the best interpretation.

[0042] Therefore, the embodiments described herein and the descriptions shown in the accompanying drawings are only the most preferred embodiments of the present disclosure, but are not intended to fully describe the technical solutions of the present disclosure. Therefore, it should be understood that various other equivalents and modifications may be made thereto when submitting this application.

[0043] Terms including ordinal numbers such as first, second, etc. are used to distinguish one element from another among various elements, but are not intended to limit the elements by the terms.

[0044] Unless the context clearly indicates otherwise, it should be understood that the term "comprising" used in this specification specifies the presence of the elements described, but does not exclude the presence or addition of one or more other elements. In addition, the term "control unit" used herein refers to a processing unit having at least one function or operation, and this can be implemented by hardware and software alone or in combination.

[0045] Furthermore, throughout this specification, it will be further understood that when an element is referred to as being “connected to” another element, it can be directly connected to the other element or intervening elements may be present.

[0046] Figure 1 is a schematic diagram exemplarily showing the configuration of a battery system according to the present disclosure.

[0047] Figure 1 An energy storage system is shown as an example of the battery system 1. Figure 1 The battery system 1 includes a battery pack 10, a switch 20, and a power conversion system 30. The battery system 1 is not limited to an energy storage system and may include any battery system having a charging function and / or a discharging function of the battery pack 10 provided therein, such as an electric vehicle or a battery tester.

[0048] The battery pack 10 includes a positive terminal P+, a negative terminal P-, a cell group 11, and a battery management device 100. The cell group 11 includes a plurality of battery cells BC_1 to BC_m (m is a natural number greater than or equal to 2) electrically connected between the positive terminal P+ and the negative terminal P-. Figure 1 The plurality of battery cells BC_1 to BC_m are shown connected in series, but the plurality of battery cells BC_1 to BC_m may also be connected in parallel, or in series and in parallel. When providing a general description of the plurality of battery cells BC_1 to BC_m below, the reference numeral "BC" is used to refer to a battery cell.

[0049] The battery cell BC may include a positive lead, a negative lead, at least one positive plate, and at least one negative plate. The positive tab of each positive plate may be coupled to the positive lead, and the negative tab of each negative plate may be coupled to the negative lead.

[0050] The positive and negative leads of a battery cell BC are electrically coupled to another battery cell BC via a conductor such as a current guide plate. The battery cell BC may be a lithium-ion battery cell. The battery cell BC is not limited to a specific type and may include any type of battery cell that can be repeatedly recharged.

[0051] The switch 20 is mounted on the power line PL for the battery pack 10. When the switch 20 is turned on, power can be transferred from either the battery pack 10 or the power conversion system 30 to the other. The switch 20 can be implemented as at least one of a known switching device such as a relay and a field effect transistor (FET). The control unit 140 can control the on / off state of the switch 20 according to the state of the cell pack 11.

[0052] The power conversion system 30 is operably coupled to the battery management device 100 via the upper controller 2. Operable coupling refers to a direct or indirect connection for transmitting and receiving signals in one or both directions. The power conversion system 30 can generate DC power for charging the cell stack 11 from the AC power supplied by the power grid 40. The power conversion system 30 can also generate AC power from the DC power supplied by the battery stack 10.

[0053] The battery management device 100 includes a voltage measurement circuit 110 and a control unit 140. The battery management device 100 may further include at least one of a current sensor 120, a temperature sensor 130, or an interface unit 150.

[0054] The voltage measurement circuit 110 is configured to be electrically connected to the positive and negative leads of the battery cells BC via voltage sensing channels. The voltage measurement circuit 110 is configured to measure the cell voltage, or the voltage across the battery cells BC, and output a signal indicating the measured cell voltage to the control unit 140. Based on the signal from the voltage measurement circuit 110, the control unit 140 can determine the cell voltage of each of the plurality of battery cells BC_1 to BC_m at preset time intervals.

[0055] The current sensor 120 is electrically connected in series with the cell stack 11 via the power line PL. For example, a shunt resistor or a Hall effect device can be used as the current sensor 120. The current sensor 120 is configured to measure the current flowing through the cell stack 11 and output a signal indicating the measured current to the control unit 140.

[0056] The temperature sensor 130 is arranged within a predetermined distance range from the cell stack 11. For example, a thermocouple may be used as the temperature sensor 130. The temperature sensor 130 is configured to measure the temperature of the cell stack 11 and output a signal indicating the measured temperature to the control unit 140.

[0057] The control unit 140 is operatively coupled to the switch 20 , the voltage measurement circuit 110 , the current sensor 120 , the temperature sensor 130 , and / or the interface unit 150 .

[0058] The control unit 140 may be implemented in hardware using at least one of an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions.

[0059] The control unit 140 may have a memory embedded therein. The memory may pre-store programs and data required to execute the battery management method according to the embodiments described below. The memory may include, for example, at least one type of storage medium selected from the group consisting of a flash memory type, a hard disk type, a solid-state disk (SSD) type, a silicon disk drive (SDD) type, a multimedia card micro, a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), and a programmable read-only memory (PROM).

[0060] The interface unit 150 can be coupled to the superior controller 2 of the battery system 1 to achieve communication. The interface unit 150 can transmit messages from the superior controller 2 to the control unit 140 and transmit messages from the control unit 140 to the superior controller 2. Messages from the control unit 140 may include information for notifying abnormalities of the battery cells BC. Communication between the interface unit 150 and the superior controller 2 can use, for example, wired networks such as local area network (LAN), controller area network (CAN), and daisy chain, and / or short-range wireless networks such as Bluetooth, Zigbee, and Wi-Fi. The interface unit 150 may include output devices (such as a display, a speaker) to provide the information received from the control unit 140 and / or the superior controller 2 in a recognizable format. The superior controller 2 can control the power conversion system 30 based on the cell information (such as voltage, current, temperature, SOC, abnormality of the battery cells) collected through communication with the battery management device 100.

[0061] The control unit 140 can operate in a diagnostic mode, in which, during at least some of the rest periods, a battery management method for detecting abnormalities of the battery cells BC as described below is executed. The start time of the rest period is the time point when the cell group 11 switches from the usage state (also referred to as the "cycle state") to the rest state (also referred to as the "rest mode" or "calendar state"). The end time of the rest period is the time point when the cell group 11 switches from the rest state to the usage state. The rest state refers to the state where the switch 20 is off and no current flows through the cell group 11, and the usage state refers to a state other than the rest state. That is, in the rest state, both charging and discharging of the battery cells BC are interrupted. [[ID=)]]

[0062] Figure 2 is a graph referred to when describing the voltage history associated with each of the normal battery cells and the defective battery cells, Figure 3 is a graph referred to when setting the cumulative change associated with each of the normal battery cells and the defective battery cells, Figure 4 is a graph referred to when describing the abnormality history associated with the battery cells. In Figure 2 the time point t0 refers to the time point when the cell group 11 switches from the discharge mode (or charge mode) to the rest state, that is, the start time of the rest period. The following description is provided assuming Figure 1 that the battery cells BC_x (1 < x < y) are normal and the battery cells BC_y (x < y < m) are defective.

[0063] Refer to Figure 2Curve 201 indicates the voltage history of a normal battery cell BC_x, curve 202 indicates the voltage history of a defective battery cell BC_y, and curve 203 indicates the reference voltage history. The voltage history of a battery cell BC refers to the change in the cell voltage of the battery cell BC over time, that is, a set of measured cell voltages (in time sequence).

[0064] In this specification, the "abnormality" to be diagnosed refers to an abnormal increase (or decrease) in the cell voltage of a battery cell BC compared to other battery cells BC during a rest period. The abnormality may be due to a defect in the terminal tab of the battery cell BC. Specifically, the inventors found that as a result of analysis after disassembling the battery cell BC that was found to be defective, damage (e.g., short circuit, rupture, tearing) was found in some positive terminal tabs and / or negative terminal tabs included in the battery cell BC. When a defect occurs in the terminal tab, the resistance between the terminal tab and the lead may change due to physical changes (e.g., expansion pressure) and / or changes in electrical and chemical properties of the battery cell BC. The resistance change affects the process of measuring the cell voltage by the voltage measurement circuit 110 and may be one of the causes of the above-mentioned abnormality.

[0065] The control unit 140 may determine the cell voltage of the battery cell BC at preset time intervals (eg, 0.01 seconds) from the start time t0 of the rest period. Figure 2 In, V X [0]、V Y [0] and V ref [0] Indicates the cell voltage of the battery cell BC_x, the cell voltage of the battery cell BC_y, and the reference voltage at the start time t0. The control unit 140 may generate (update) cell voltage data based on the cell voltage of the battery cell BC. The cell voltage data may include information indicating the cell voltage, the first voltage change, and the first cumulative change of the battery cell BC. That is, the control unit 140 may determine the cell voltage, the first voltage change, and the first cumulative change of the battery cell BC at preset time intervals. The first voltage change indicates the change in the cell voltage of the battery cell BC at preset time intervals. For example, the first voltage change in the current cycle corresponds to (e.g., is equal to) the difference between the cell voltage in the previous cycle and the cell voltage in the current cycle. The first cumulative change indicates the total change in the cell voltage of the battery cell BC from the start time t0 of the rest period to the current time. For example, the first cumulative change in the current cycle is the result of accumulating the first voltage changes at preset time intervals during the rest period, and may correspond to (e.g., is equal to) the difference between the cell voltage at the start time t0 and the cell voltage in the current cycle.

[0066] A first cumulative change in the cell voltage of the battery cell BC may be expressed as Equation 1 below.

[0067] <Equation 1>

[0068]

[0069] In Equation 1, n indicates the number of times a preset time has elapsed from the start time t0, V cell [i-1] indicates the (i-1)th measurement cell voltage, V cell [i] indicates the voltage of the i-th measurement cell, ΔV cell [i] indicates the first voltage change determined in the i-th order, ΔV cell_acc [n] indicates the first cumulative change. V cell [0] may be the cell voltage at the start time t0. In addition, n is a time index corresponding to the length of time from the start time t0 to the current time, and is increased by 1 each time the preset time elapses. For example, where the preset time = Δt, the total time period from the time point t0 to the current time = Δt×n, and the current time = t0+(Δt×n). In addition, V cell [i] indicates the cell voltage of the battery cell BC measured at the time point t0 + (Δt×i).

[0070] As described above, cell voltage data may be generated for each of the plurality of battery cells BC_1 to BC_m at preset time intervals. The control unit 140 may generate reference voltage data for the plurality of battery cells BC_1 to BC_m based on the cell voltage data generated for each of the plurality of battery cells BC_1 to BC_m. The reference voltage data may include information indicating the reference voltage, the second voltage change, and the second cumulative change.

[0071] The reference voltage may be determined to be equal to an average or median value of the cell voltages of the plurality of battery cells BC_1 to BC_m at preset time intervals. The second voltage change indicates a change in the reference voltage at preset time intervals. For example, the second voltage change in the current cycle corresponds to (e.g., is equal to) the difference between the reference voltage in the previous cycle and the reference voltage in the current cycle. Figure 2 The curve 203 indicates the timing change of the reference voltage. Figure 2 As shown, the voltage history 201 of the normal battery cell BC_x substantially matches the curve 203. The second cumulative change indicates the total change in the reference voltage from the start time t0 of the rest period to the current time. For example, the second cumulative change in the current cycle is the result of accumulating the second voltage change at preset time intervals during the rest period, and may correspond to (e.g., be equal to) the difference between the reference voltage at the start time t0 and the reference voltage in the current cycle.

[0072] The second cumulative variation of the reference voltages of the plurality of battery cells BC_1 ˜BC_m may be expressed as Equation 2 below.

[0073] <Equation 2>

[0074]

[0075] In Equation 2, n is the same as in Equation 1, and V ref [i-1] indicates the (i-1)th reference voltage, V ref [i] indicates the i-th determined reference voltage, ΔV ref [i] indicates the second voltage change determined by the i-th step, ΔV ref_acc [n] indicates the second cumulative change.

[0076] Reference Figure 3 , curve 301 indicates Figure 2 The curve 201 corresponds to the timing change of the first cumulative change of the battery cell BC_x, and the curve 302 indicates the timing change of the first cumulative change of the battery cell BC_x. Figure 2 The curve 202 corresponds to the timing change of the first cumulative change of the battery cell BC_y, and the curve 303 indicates the timing change of the first cumulative change of the battery cell BC_y. Figure 2 The curve 203 corresponds to the timing change of the second cumulative change of the reference voltage.

[0077] The control unit 140 may determine whether each of the plurality of battery cells BC_1 ˜BC_m is defective by comparing each of the plurality of first cumulative changes with the second cumulative change. The plurality of first cumulative changes and the plurality of battery cells BC_1 ˜BC_m are associated in a one-to-one relationship.

[0078] Specifically, the control unit 140 can determine (update) the abnormality history associated with the battery cell BC at a preset time interval by calculating the difference between the first cumulative change and the second cumulative change associated with the battery cell BC, and store the determined abnormality history in the memory. Therefore, a plurality of abnormality histories associated with the plurality of battery cells BC_1 to BC_m in a one-to-one relationship can be updated at a preset time interval. The abnormality history associated with the battery cell BC indicates the difference between the first cumulative change of the cell voltage of the battery cell BC and the second cumulative change of the reference voltage, that is, (ΔV cell_acc [n]-ΔV ref_acc [n]) or (ΔV ref_acc [n]-ΔV cell_acc [n]) timing changes.

[0079] The control unit 140 may determine each of a maximum value and a minimum value of the abnormality history associated with the battery cell BC at preset time intervals, and determine whether the battery cell BC is defective based on the maximum value and the minimum value. Figure 4 The curve 401 indicates that Figure 3The abnormal history of the battery cell BC_x corresponding to the curve 301, the curve 402 indicates the abnormal history of the battery cell BC_x corresponding to the curve 301, and the curve 402 indicates the abnormal history of the battery cell BC_x corresponding to the curve 402. Figure 3 The abnormal history of the battery cell BC_y corresponding to the curve 302 is shown in FIG. 4 . Since the battery cell BC_x is normal, the cell voltage of the battery cell BC_x exhibits behavior that is almost similar to the reference voltage during the rest period. That is, the curve 401 indicates that during the entire rest period, the abnormal history associated with the battery cell BC_x is only limited by the first threshold V TH1 and the second threshold V TH2 Defines the voltage range to be processed. The first threshold V TH1 can be a positive value, and the second threshold V TH2 It can be a negative value. In contrast to the battery cell BC_x, since the battery cell BC_y is defective, the cell voltage of the battery cell BC_y is very inconsistent with the behavior of the reference voltage during the rest period. That is, the curve 402 indicates the maximum value V of the abnormal history associated with the battery cell BC_y. max and minimum value V min Each of the TH1 and is less than the second threshold V TH2 . Maximum value V max At time t A The difference between the first cumulative change of the cell voltage of the battery cell BC_y and the second cumulative change of the reference voltage, and the minimum value V min At time t B The difference between the first cumulative change in the cell voltage of the battery cell BC_y and the second cumulative change in the reference voltage.

[0080] The control unit 140 may determine that among the multiple abnormal histories, the maximum value is greater than the first threshold V TH1 And the minimum value is less than the second threshold V TH2 The battery cell (eg, BC_y) associated with the abnormal history is defective.

[0081] Alternatively, the control unit 140 may determine that among the plurality of abnormal histories, the maximum value is greater than the first threshold value V TH1 , the minimum value is less than the second threshold V TH2 And the battery cell BC associated with each abnormal history whose absolute value of the slope between the maximum value and the minimum value is greater than the third threshold value is defective. Here, the slope between the maximum value and the minimum value is a value obtained by dividing the difference between the maximum value and the minimum value by the time interval between the two time points at which the maximum value and the minimum value are detected. For example, in the curve 402, the maximum value V max With the minimum value V min The slope between them is equal to (V max -V min ) / (tA -t B ).

[0082] Each of the above-mentioned threshold values ​​may be preset according to the results of experiments and / or simulations performed based on the total number of battery cells BC included in the cell group 11 and the battery cell BC specifications.

[0083] Figure 5 is a flowchart exemplarily illustrating a battery management method according to the first embodiment of the present disclosure. Figure 5 The method may start from the start time t0 of the rest period and be repeated at preset time intervals.

[0084] Reference Figures 1 to 5 In step S510 , the control unit 140 determines (measures) the cell voltage of each of the plurality of battery cells BC_1 ˜BC_m included in the cell group 11 using the voltage measurement circuit 110 .

[0085] In step S520 , the control unit 140 determines a reference voltage of the plurality of battery cells BC_1 ˜BC_m based on the cell voltage of each of the plurality of battery cells BC_1 ˜BC_m. The reference voltage may be equal to an average value or a median value of the cell voltages of the plurality of battery cells BC_1 ˜BC_m.

[0086] In step S530 , the control unit 140 determines a first cumulative change ΔV in the cell voltage of each of the plurality of battery cells BC_1 ˜BC_m. cell_acc [n] (see Equation 1).

[0087] In step S540, the control unit 140 determines a second cumulative variation ΔV of the reference voltage. ref_acc [n] (see Equation 2).

[0088] In step S550 , the control unit 140 determines a plurality of abnormal histories respectively associated with the plurality of battery cells BC_1 ˜BC_m, which indicate a time-series change in the difference between the first cumulative change and the second cumulative change of each of the plurality of battery cells BC_1 ˜BC_m.

[0089] In step S560 , the control unit 140 determines a maximum value and a minimum value of each of the plurality of abnormality histories.

[0090] In step S570, the control unit 140 determines a maximum value V for each of the plurality of abnormality histories. max Is it greater than the threshold V TH1 And the minimum value V min Is it less than the second threshold V TH2For battery cell BC_x, the value of step S570 is "No," while for battery cell BC_y, the value of step S570 may be "Yes." When the value of step S570 is "Yes," the method proceeds to step S580. That is, step S580 may be performed when at least one of the plurality of battery cells BC_1 to BC_m is determined to be defective. When the value of step S570 is "No," the method may end.

[0091] In step S580, the control unit 140 may execute a predetermined protection function. The protection function may include outputting a diagnostic message. The diagnostic message may include identification information of the battery cell BC determined to be defective. The interface unit 150 may transmit the diagnostic message to the superior controller 2 or output visual and / or audible information corresponding to the diagnostic message. The protection function may include inhibiting the switch 20 from being turned on, i.e., interrupting the switching of the cell pack 11 from the rest state to the active state.

[0092] Figure 6 is a flowchart exemplarily illustrating a battery management method according to a second embodiment of the present disclosure. Figure 6 The method may be repeated at preset time intervals during the rest period. Figure 6 Steps S610 to S660 and S680 are the same as Figure 5 Steps S510 to S560 and S580 are identical, and step S670 is a variant of step S570. Figure 6 The method can be omitted with Figure 5 The method is the same as described.

[0093] Reference Figures 1 to 4 and Figure 6 In step S610 , the control unit 140 determines (measures) a cell voltage of each of the plurality of battery cells BC_1 ˜BC_m.

[0094] In step S620 , the control unit 140 determines a reference voltage of the plurality of battery cells BC_1 ˜BC_m based on the cell voltage of each of the plurality of battery cells BC_1 ˜BC_m.

[0095] In step S630 , the control unit 140 determines a first cumulative change ΔV of the cell voltage of each of the plurality of battery cells BC_1 ˜BC_m. cell_acc [n] (see Equation 1).

[0096] In step S640, the control unit 140 determines a second cumulative variation ΔV of the reference voltage. ref_acc [n] (see Equation 2).

[0097] In step S650 , the control unit 140 determines a plurality of abnormality histories associated with each of the plurality of battery cells BC_1 ˜BC_m.

[0098] In step S660 , the control unit 140 determines the maximum value and the minimum value of each of the plurality of abnormality histories.

[0099] In step S670, the control unit 140 determines a maximum value V for each of the plurality of abnormality histories. max Is it greater than the threshold V TH1 , minimum value V min Is it less than the second threshold V TH2 , and whether the absolute value of the slope between the maximum value and the minimum value is greater than a third threshold value. When the value of step S670 is "yes", the method proceeds to step S680. When the value of step S670 is "no", the method can end.

[0100] In step S680 , the control unit 140 may perform a predetermined protection function.

[0101] Meanwhile, regarding the above-mentioned polarization, the polarization occurring in the normal battery cells tends to decrease rapidly in the early stage of the rest period. That is, in the rest period, the cell voltage change rate of the normal battery cells BC_x can be slowed down. Therefore, the control unit 140 can be configured to execute the above-mentioned diagnostic procedure from a reference time point at which a predetermined stabilization time (e.g., 5 minutes) has elapsed from the start time t0, rather than executing the above-mentioned diagnostic procedure immediately from the start time t0. In this case, the reference time point t0 is used to determine the time at which the predetermined stabilization time (e.g., 5 minutes) has elapsed. Figure 1 The start time t0 described up to FIG. 7 may be replaced with a reference time point.

[0102] The above-mentioned embodiments of the present disclosure are not only implemented by devices and methods, but also by programs that execute functions corresponding to the configurations of the embodiments of the present disclosure or recording media on which the programs are recorded, and those skilled in the art can easily implement these implementation methods through the disclosure of the above-mentioned embodiments.

[0103] Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it is obvious to those skilled in the art that various modifications and variations may be made thereto within the scope of equivalents of the technical solutions of the present disclosure and the appended claims.

[0104] In addition, because those skilled in the art can make various replacements, modifications and changes to the above-mentioned disclosure without departing from the technical solution of the present disclosure, the present disclosure is not limited to the above-mentioned embodiments and drawings, and some or all of the embodiments can be selectively combined to allow various modifications.

Claims

1. A battery management device, comprising: a voltage measurement circuit configured to measure a cell voltage of each of the plurality of battery cells; as well as a control unit configured to determine a cell voltage of each of the plurality of battery cells and a reference voltage of the plurality of battery cells at preset time intervals during a rest period, Wherein, the control unit is configured as follows: determining a first cumulative change in the cell voltage of each battery cell by accumulating changes in the cell voltage of each battery cell at the preset time intervals during the rest period, wherein the first cumulative change indicates a total change in the cell voltage of the corresponding battery cell since a start time of the rest period, determining a second cumulative change in the reference voltage by accumulating changes in the reference voltage at the preset time intervals during the rest period, wherein the second cumulative change indicates a total change in the reference voltage since a start time of the rest period, and Whether each battery cell is defective is determined by comparing the first cumulative change and the second cumulative change.

2. The battery management device according to claim 1, wherein: The control unit is configured to determine the reference voltage to be equal to an average value or a median value of cell voltages of the plurality of battery cells.

3. The battery management device according to claim 1, wherein: The control unit is configured to: determining an abnormality history at the preset time intervals during the rest period, the abnormality history indicating a time-series change in a difference between the first cumulative change and the second cumulative change of each battery cell, and It is determined whether each battery cell is defective based on a maximum value and a minimum value of the abnormality history associated with each battery cell.

4. The battery management device according to claim 3, wherein: The control unit is configured to determine that each battery cell among the plurality of battery cells associated with an abnormality history in which the maximum value is greater than a first threshold and the minimum value is less than a second threshold is defective.

5. The battery management device according to claim 3, wherein: The control unit is configured to determine that each battery cell among the plurality of battery cells that is associated with an abnormal history in which the maximum value is greater than a first threshold, the minimum value is less than a second threshold, and an absolute value of a slope between the maximum value and the minimum value is greater than a third threshold is defective. 6 . A battery pack comprising the battery management device according to claim 1 .

7. A battery system comprising the battery pack according to claim 6.

8. A battery management method performed at preset time intervals during a rest period of a plurality of battery cells, the battery management method comprising: determining a cell voltage of each of the plurality of battery cells and a reference voltage of the plurality of battery cells; determining a first cumulative change in the cell voltage of each battery cell by accumulating changes in the cell voltage of each battery cell at the preset time intervals during the rest period, wherein the first cumulative change indicates a total change in the cell voltage of the corresponding battery cell since a start time of the rest period; determining a second cumulative change in the reference voltage by accumulating changes in the reference voltage at the preset time intervals during the rest period, wherein the second cumulative change indicates a total change in the reference voltage since a start time of the rest period; as well as Whether each of the plurality of battery cells is defective is determined by comparing the first cumulative change and the second cumulative change.

9. The battery management method according to claim 8, wherein: Determining whether each of the plurality of battery cells is defective includes: determining an abnormality history at the preset time intervals during the rest period, the abnormality history indicating a time-series change in a difference between the first cumulative change and the second cumulative change of each battery cell, and It is determined whether each battery cell is defective based on a maximum value and a minimum value of the abnormality history associated with each battery cell.

10. The battery management method according to claim 9, wherein: Determining whether each of the plurality of battery cells is defective includes determining that each of the plurality of battery cells associated with an abnormality history in which the maximum value is greater than a first threshold and the minimum value is less than a second threshold is defective.

11. The battery management method according to claim 9, wherein: Determining whether each of the plurality of battery cells is defective includes determining that each of the plurality of battery cells that is associated with an abnormal history in which the maximum value is greater than a first threshold, the minimum value is less than a second threshold, and the absolute value of the slope between the maximum value and the minimum value is greater than a third threshold is defective.

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