Battery management system, battery pack, electric vehicle and battery management method

Abstract

A battery management system according to the present invention includes a swelling detector including at least one sensor configured to detect a swelling state of a battery cell, and a control circuit configured to generate first time-series data of the swelling state repeatedly detected during a charging process included in a charge / discharge cycle of the battery cell. The control circuit is configured to determine a first amount of change in the swelling state during the charging process from the first time-series data. The control circuit is configured to determine whether the battery cell has an internal short circuit fault based on the first amount of change.

Description

[Technical field]

[0001] The present invention relates to a technique for detecting an internal short circuit fault in a battery cell.

[0002] This application claims priority to Korean Patent Application No. 10-2021-0089983, filed on July 8, 2021, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings. [Background technology]

[0003] Recently, as the demand for portable electronic products such as notebook PCs, video cameras, and mobile phones has increased sharply and the development of electric vehicles, energy storage batteries, robots, satellites, etc. has progressed in earnest, research into high-performance batteries that can be repeatedly charged and discharged is progressing actively.

[0004] Currently, commercial batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are in the spotlight due to their advantages over nickel-based batteries, such as almost no memory effect, freedom to charge and discharge, a very low self-discharge rate, and high energy density.

[0005] 2. Description of the Related Art In order to meet the high voltage and large capacity requirements of applications such as electric vehicles, battery modules including a plurality of battery cells connected in series have become widespread.

[0006] In a battery module, failure of some battery cells is likely to adversely affect the overall performance and safety of the battery system, so it is important to properly detect failures of individual battery cells when operating the battery system.

[0007] Among the various types of battery cell failures, an internal short circuit failure is the main failure that directly or indirectly affects fires. An internal short circuit failure is also called a "micro short circuit" and occurs due to side reactions within the battery cell (e.g., the formation of deposits on the negative electrode surface) and / or the penetration of foreign matter.

[0008] Conventionally, an internal short circuit fault in each battery cell is detected by comparing the drop in the open circuit voltage (OCV) of the battery cell during rest with a predetermined value or the average drop in the voltage of other battery cells. However, since the OCV of a battery cell during rest drops very slowly, it takes a long time to detect an internal short circuit fault from the drop in the OCV. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above problems, and aims to provide a battery management system, a battery pack, an electric vehicle, and a battery management method that detect an internal short circuit failure of a battery cell by analyzing time series data on a swelling status of a battery cell detected during a charge / discharge cycle based on a correlation between the swelling status of the battery cell and an internal short circuit failure.

[0010] Other objects and advantages of the present invention will become apparent from the following description and the embodiments of the present invention, and can be realized by the means and combinations thereof as claimed in the appended claims. [Means for solving the problem]

[0011] According to an aspect of the present invention, a battery management system includes a swelling detector including at least one sensor configured to detect a swelling state of a battery cell, and a control circuit configured to generate first time series data of the swelling state repeatedly detected during a charging process included in a charge / discharge cycle for the battery cell, the control circuit configured to determine a first amount of change in the swelling state due to the charging process from the first time series data, and determine whether the battery cell has an internal short circuit fault based on the first amount of change.

[0012] The swelling state is a thickness of the battery cell or a load acting on the battery cell.

[0013] The control circuit may be configured to determine, as the first amount of change, a difference between a minimum swelling state and a maximum swelling state of the first time series data, or a difference between a swelling state detected at a predetermined time after a start of the charging process and a maximum swelling state of the first time series data.

[0014] The control circuit may be configured to determine that the battery cell has an internal short circuit fault when the first change amount is equal to or greater than a first critical change amount.

[0015] The control circuit may be configured to generate second time series data of the swelling state detected repeatedly during a discharging process included in the charge / discharge cycle to be performed after the charging process. The control circuit may be configured to determine a second amount of change in the swelling state from the first time series data and the second time series data. The second amount of change may be a difference between a minimum swelling state of the first time series data and a minimum swelling state of the second time series data. The control circuit may be configured to determine whether the battery cell has an internal short circuit fault based on the first amount of change and the second amount of change.

[0016] The control circuit may be configured to determine that the battery cell has an internal short circuit fault when the first change amount is a first critical change amount and the second change amount is equal to or greater than a second critical change amount.

[0017] The battery management system may further include a current detector configured to detect a battery current flowing through the battery cell. The control circuit may be configured to generate third time series data of the battery current repeatedly detected during the charging process. The control circuit may be configured to generate fourth time series data of the battery current repeatedly detected during the discharging process. The control circuit may be configured to determine a first integrated amount of the battery current during the charging process from the third time series data and a second integrated amount of the battery current during the discharging process from the fourth time series data. The control circuit may be configured to determine that the battery cell has an internal short circuit fault when (i) the first change amount is equal to or greater than a first critical change amount, (ii) the second change amount is equal to or greater than a second critical change amount, and (iii) a ratio of the second integrated amount to the first integrated amount is less than a critical ratio.

[0018] The control circuit may be configured to determine a first average rate of change of the swelling condition at an early stage of the charging process and a second average rate of change of the swelling condition at a later stage of the charging process from the first time-series data. The control circuit may be configured to determine that the battery cell has an internal short circuit fault when (i) the first amount of change is equal to or greater than a first critical amount of change, and (ii) a ratio of the second average rate of change to the first average rate of change is equal to or greater than a critical ratio.

[0019] A battery pack according to another aspect of the present invention includes the battery management system.

[0020] According to yet another aspect of the present invention, an electric vehicle includes the battery pack described above.

[0021] According to another aspect of the present invention, a battery management method includes generating first time series data of a swelling state of a battery cell repeatedly detected during a charging process included in a charge / discharge cycle of the battery cell, determining a first change amount of the swelling state from the first time series data, and determining whether the battery cell has an internal short circuit failure based on the first change amount.

[0022] The step of determining a first amount of change in the swelling state may determine, as the first amount of change, a difference between a minimum swelling state and a maximum swelling state of the first time series data, or a difference between a swelling state detected at a predetermined time point after a start of the charging process and a maximum swelling state of the first time series data.

[0023] The determining whether the battery cell has an internal short circuit failure may determine that the battery cell has an internal short circuit failure when the first change amount is equal to or greater than a first critical change amount.

[0024] The battery management method may further include generating second time series data of the swelling state repeatedly detected during a discharging process included in the charge / discharge cycle to be performed after the charging process, and determining a second amount of change in the swelling state from the first time series data and the second time series data, the second amount of change being a difference between a minimum swelling state of the first time series data and a minimum swelling state of the second time series data. The determining whether the battery cell has an internal short circuit failure may determine whether the battery cell has an internal short circuit failure based on the first amount of change and the second amount of change.

[0025] The battery management method may further include generating third time series data of the battery current flowing through the battery cell repeatedly detected during the charging process, generating fourth time series data of the battery current repeatedly detected during the discharging process, and determining a first accumulated amount of the battery current during the charging process and a second accumulated amount of the battery current during the discharging process from the third time series data and the fourth time series data.

[0026] The step of determining whether the battery cell has an internal short circuit fault may determine that the battery cell has an internal short circuit fault if (i) the first change amount is equal to or greater than a first critical change amount, (ii) the second change amount is equal to or greater than a second critical change amount, and (iii) a ratio of the second integrated amount to the first integrated amount is less than a critical ratio. Effect of the Invention

[0027] According to at least one embodiment of the present invention, based on a correlation between the swelling state of a battery cell and an internal short circuit failure, it is possible to detect an internal short circuit failure of a battery cell by analyzing time series data on the swelling state of the battery cell detected during a charge / discharge cycle.

[0028] In addition, according to at least one embodiment of the present invention, by additionally utilizing time series data on the battery current detected in synchronization with the swelling state of the battery cell, it is possible to more accurately detect an internal short circuit fault in the battery cell.

[0029] The effects of the present invention are not limited to the effects described above, and other effects of the present invention not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0030] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief description of the drawings]

[0031] [Figure 1] 1 is a diagram showing the configuration of an electric vehicle according to the present invention;

[0032] [Diagram 2] 1 is a reference diagram for explaining an exemplary equivalent circuit of a battery cell;

[0033] [Diagram 3] 1 is a graph showing changes over time in the swelling state of a battery cell during charge / discharge cycles.

[0034] [Figure 4] 2 is a flowchart showing a battery management method according to a first embodiment of the present invention.

[0035] [Diagram 5] 5 is a flowchart illustrating a battery management method according to a second embodiment of the present invention.

[0036] [Figure 6] 10 is a flowchart illustrating a battery management method according to a third embodiment of the present invention.

[0037] [Figure 7] 10 is a flowchart illustrating a battery management method according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as having meanings and concepts according to the technical ideas of the present invention, in accordance with the principle that the inventor himself can appropriately define the concepts of terms in order to best describe the invention.

[0039] Therefore, it should be understood that the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted for them at the time of this application.

[0040] Terms including ordinal numbers such as "first", "second", etc. are used for the purpose of distinguishing one of various components from the rest, and are not intended to limit the components.

[0041] In addition, throughout the specification, when a part "includes" a certain element, this does not mean excluding other elements, but means that the part may further include other elements, unless otherwise specified. Furthermore, terms such as "control unit" in the specification refer to a unit that processes at least one function or operation, which may be realized by hardware, software, or a combination of hardware and software.

[0042] Furthermore, throughout this specification, when a part is said to be "connected" to another part, this includes not only when it is "directly connected" to another part, but also when it is "indirectly connected" through another element in between.

[0043] FIG. 1 is a diagram showing the configuration of an electric vehicle according to the present invention.

[0044] 1, an electric vehicle 1 includes a vehicle controller 2, a battery pack 10, and an electric load 30. Charging and discharging terminals P+, P- of the battery pack 10 may be electrically coupled to the electric load 30 and a charger 40. The charger 40 may be included in the electric vehicle 1 or may be provided in a charging station.

[0045] The vehicle controller 2 (e.g., ECU: Electronic Control Unit) is configured to transmit a key-on signal to the battery management system 100 in response to a start button (not shown) provided on the electric vehicle 1 being switched to an on position by a user. The vehicle controller 2 is configured to transmit a key-off signal to the battery management system 100 in response to a start button being switched to an off position by a user. The charger 40 can communicate with the vehicle controller 2 to supply constant current or constant voltage charging power via the charging / discharging terminals P+, P- of the battery pack 10.

[0046] The battery pack 10 includes a battery module BM, a relay 20, and a battery management system 100. Although the battery pack 10 includes a single battery module BM in FIG. 1, two or more battery modules BM may be included in the battery pack 10 in series, parallel, or a combination of series and parallel.

[0047] The battery module BM is made up of multiple battery cells BC 1 ~BC N (N is a natural number equal to or greater than 2). 1 ~BC N are connected in series with each other. 1 ~BC N In FIG. 1, a plurality of battery cells BC 1 ~BC N B.C. 1 From B.C. N The battery cells (e.g., BC 1 ) is connected to other adjacent battery cells (e.g., BC) by spacers (not shown) of the battery module BM. 2 ) at a predetermined distance from each other. 1 ) due to swelling of other battery cells (e.g., BC 2) can be eliminated.

[0048] In the following, multiple battery cells BC 1 ~BC N In describing the contents common to the above, the battery cell is denoted by the symbol "BC." The type of the battery cell BC is not particularly limited as long as it is capable of repeated charging and discharging, such as a lithium ion cell.

[0049] The relay 20 is electrically connected in series to the battery module BM through a power path connecting the battery module BM and the inverter 31. In FIG. 1, the relay 20 is shown connected between the positive terminal of the battery module BM and the charge / discharge terminal P+. The relay 20 is controlled to be turned on and off in response to a switching signal from the battery management system 100. The relay 20 may be a mechanical contactor that is turned on and off by the magnetic force of a coil, or a semiconductor switch such as a metal oxide semiconductor field effect transistor (MOSFET).

[0050] The electric load 30 includes an inverter 31 and an electric motor 32. The inverter 31 is provided to convert a direct current from the battery module BM included in the battery pack 10 into an alternating current in response to a command from the battery management system 100 or the vehicle controller 2. The electric motor 32 is driven using the AC power from the inverter 31. As the electric motor 32, for example, a three-phase AC motor may be used.

[0051] The battery management system 100 includes a swelling detector 110 and a control circuit 150. The battery management system 100 may further include at least one of a voltage detector 120, a current detector 130, and a communication circuit 160.

[0052] The swelling detector 110 detects the swelling of a plurality of battery cells BC 1 ~BC Nand generating a swelling signal indicative of the detected swelling state.

[0053] The swelling detector 110 includes a plurality of swelling sensors W 1 ~W N , or W 1 ~W N+1 In the following, a plurality of swelling sensors W 1 ~W N In describing the contents common to the above, the symbol "W" is given to the swelling sensor. The swelling state may be the thickness of the battery cell BC or the load acting on the battery cell BC detected by the swelling sensor W in a state of contacting or not contacting the battery cell BC. The swelling state may also be referred to as a swelling amount or a swelling value. The swelling sensor W may be implemented by any one or a combination of two or more of known swelling detection elements such as an infrared sensor, a strain gauge, a piezoelectric sensor, an image sensor, etc.

[0054] Assume that i is a natural number less than or equal to N. Figure 1 shows a battery cell BC 1 ~BC N Based on the alignment direction of battery cell BC i Two swelling sensors on both sides of the i , W i+1 It shows that the position of

[0055] For example, battery cell BC i The swelling state of the swelling sensor W i Or Swelling Sensor W i+1 In another example, the battery cell BC i The swelling state of the battery cell BC i Two swelling sensors are located on either side of the i , W i+1 can be detected by

[0056] The voltage detector 120 detects a plurality of battery cells BC 1 ~BC N The cell voltages are connected to the positive and negative terminals of each of the battery cells BC and configured to detect the voltage across the battery cell BC and generate a voltage signal indicative of the detected cell voltage.

[0057] The current detector 130 is connected in series to the battery module BM through a current path between the battery module BM and the inverter 31. The current detector 130 is configured to detect a battery current flowing through the battery module BM and generate a current signal indicative of the detected battery current. 1 ~BC N are connected in series, so multiple battery cells BC 1 ~BC N A common battery current flows through the current detector 130. The current detector 130 may be implemented by any one or a combination of two or more known current detection elements such as a shunt resistor, a Hall element, etc.

[0058] The communication circuit 160 is configured to support wired or wireless communication between the control circuit 150 and the vehicle controller 2. The wired communication may be, for example, CAN (controller area network) communication, and the wireless communication may be, for example, ZigBee (registered trademark) or Bluetooth (registered trademark) communication. Of course, the type of communication protocol is not particularly limited as long as it supports wired or wireless communication between the control circuit 150 and the vehicle controller 2. The communication circuit 160 may include an output device (for example, a display, a speaker) that provides information received from the control circuit 150 and / or the vehicle controller 2 in a form that can be recognized by a user (driver).

[0059] The control circuit 150 may be referred to as a "battery controller" and may be implemented in hardware using at least one of an ASIC (application specific integrated circuit), a DSP (digital signal processor), a DSPD (digital signal processing device), a PLD (programmable logic device), an FPGA (field programmable gate array), a microprocessor, or other electrical unit for performing a function.

[0060] The control circuit 150 is operatively coupled to the relay 20, the detectors 110, 120, 130 and / or the communication circuit 160. When two components are operatively coupled, it means that the two components are directly or indirectly connected to each other so that signals can be sent and received unidirectionally or bidirectionally.

[0061] The control circuit 150 may collect the voltage signal from the voltage detector 120 and / or the current signal from the current detector 130 at regular time intervals during charging, discharging, and / or resting of the battery module BM. That is, the control circuit 150 may obtain the swelling detection value, the voltage detection value, and / or the current detection value from the analog signals collected from the detectors 110, 120, and 130 using an ADC (Analog to Digital Converter) provided inside, and record the obtained values ​​in the memory 151. In this way, time series data of the swelling state, voltage, and / or battery current of the battery cell BC is generated. For reference, time series data refers to a set (sequence) of values ​​obtained in chronological order over an arbitrary period of time.

[0062] The memory 151 may include at least one type of storage medium, for example, a flash memory type, a hard disk type, a solid state disk type (SSD type), a silicon disk drive type (SDD type), a multimedia card micro type, 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). The memory 151 may store data and programs required for the arithmetic operation by the control circuit 150. The memory 151 may store data indicating the result of the arithmetic operation by the control circuit 150. The memory 151 may store various algorithms applied to the detection of an internal short circuit fault of the battery cell BC. The memory 151 may be integrated within the control circuitry 150 .

[0063] When the relay 20 is turned on during operation of the electrical load 30 and / or the charger 40, the battery module BM is in a charging mode or a discharging mode. When the relay 20 is turned off while the battery module BM is in use in a charging mode or a discharging mode, the battery module BM is switched to a rest state.

[0064] The control circuit 150 may turn on the relay 20 in response to a key-on signal. The control circuit 150 may turn off the relay 20 in response to a key-off signal. The key-on signal is a signal requesting switching from a pause state to charging or discharging. The key-off signal is a signal requesting switching from charging or discharging to a pause state. Alternatively, the on / off control of the relay 20 may be handled by the vehicle controller 2 instead of the control circuit 150.

[0065] During charging of the battery pack 10, the control circuit 150 controls the multiple battery cells BC 1 ~BC N The voltage of each of the battery cells BC is monitored. 1 ~BC N The maximum voltage may be determined by the number of battery cells BC. 1 ~BC N It is the largest of the voltages.

[0066] The control circuit 150 may control the electric load 30 and the charger 40 to perform a charge / discharge cycle in order to detect an internal short circuit fault in the battery cell BC. The charge / discharge cycle may be (i) a continuous charging process and a continuous discharging process, or (iii) a continuous charging process, a continuous resting process, and a continuous discharging process. The charging process may be started on the condition that the OCV of the battery cell BC is equal to or lower than a predetermined voltage level (e.g., 3.1 V). The charging process may be performed according to a known constant current (CC)-constant voltage (CV) profile. The current rate of the CC and the charging voltage of the CV may be predetermined according to the electrochemical specifications of the battery cell BC. The charging process may be ended on the condition that the battery current of the CV reaches a predetermined cutoff current (e.g., 0.05 A). The resting process is started at the end of the charging process. The resting process is for stabilizing electrochemical instability of the battery cell BC caused by the charging process. The discharging process is started at the end of the resting process. The current level of the CC charging (e.g., 0.65A), the voltage level of the CV charging (e.g., 4.25V), and the duration of the resting process (e.g., 30 minutes) are each appropriately predetermined in consideration of the specifications and characteristics of the battery cell BC. The current level of the discharging process (e.g., -1.0A) is each appropriately predetermined in consideration of the specifications and characteristics of the battery cell BC.

[0067] Of course, the charge / discharge cycle is not limited to the above, and may be modified in any manner so long as it is possible to observe the swelling state that reflects a clear correlation with the internal short circuit failure.

[0068] Fig. 2 is a diagram referred to for explaining an exemplary equivalent circuit of a battery cell, and Fig. 3 is a graph showing a change over time in the swelling state of a battery cell during a charge / discharge cycle. In this specification, a faulty battery cell refers to a battery cell that has an internal short circuit fault, unlike a normal battery cell.

[0069] Referring to FIG. 2, a normal battery cell is connected to a DC voltage source V DC , internal resistance component R 0and RC pair R 1 , C. In contrast, the faulty battery cell can be equivalent to an additional resistance component R between both ends of the series circuit corresponding to the normal battery cell. ISC can be equivalent to the additional resistance R ISC is the leakage current I ISC The internal short circuit R acts as a path for the ISC The decrease in the resistance value of means that the internal short circuit fault becomes severe, and the more severe the internal short circuit fault becomes, the greater the leakage current I ISC As a result, the amount of power consumed may increase.

[0070] 3 shows the change over time of the swelling state due to a charge / discharge cycle including a charging process, a resting process, and a constant current discharge process according to a predetermined CC-CV profile. In FIG. 3, curve 310 shows the swelling state of a normal battery cell, and curve 320 shows the swelling state of a faulty battery cell. For ease of understanding, the start time of the charging process related to the two curves 410 and 420 is set to the same time t0, and it is assumed that the swelling states of the normal battery cell and the faulty battery cell at time t0 are the same as S0.

[0071] In the curve 310, t1, t2, and t3 are the end of the charging process (= the start of the resting process), the end of the resting process (= the start of the discharging process), and the end of the discharging process (= the completion of the charge / discharge cycle) for a normal battery cell, respectively. In the curve 310, the swelling state continues to increase from time t0 to time t1. That is, in the curve 310, the swelling state of the charging process is maximum at time t1.

[0072] In the curve 320, t11, t12, and t13 are the end points of the charging process, the end point of the resting process, and the end point of the discharging process for the faulty battery cell, respectively. In the curve 320, the peak P of the maximum swelling state SP is located at a time tP before the time t11, and the maximum swelling state SP is greater than the swelling state SB at the end of the charging process. That is, in the curve 320, the swelling state continues to increase from the time t0, reaches the maximum value SP at the time tP, and then continues to decrease from the time tP to the time t11. It is presumed that the reason why the peak P appears before the end of the charging process is that the charging current continues to decrease during the constant voltage charging due to the switching from the constant current charging to the constant voltage charging around the time tP, and such a change in the charging current has a relatively larger effect on the swelling state of the faulty battery cell than that of the normal battery cell.

[0073] During the charging process, in contrast to the normal battery cells, a part of the charging power remains unstored in the faulty battery cell, resulting in a leakage current I ISC As a result, in the faulty battery cell, the temperature rise, gas generation, expansion of the electrode material, and growth of deposits (e.g., lithium metal) accelerate, resulting in more severe swelling. Also, the time required for the charging process for the faulty battery cell (t11-t0) is longer than the time required for the charging process for the normal battery cell (t1-t0).

[0074] The inventors of the present invention have confirmed that the swelling state of a faulty battery cell increases faster in the later period tB-t1 of the charging process than in the early period t0-tA. This phenomenon is mainly due to two reasons: (i) the leakage current I ISC This may be the result of a combination of (i) the internal instability of the faulty battery cell accumulating during the charging process, and (ii) the gradual increase in the voltage of the faulty battery cell during the charging process. The cause (ii) is the increase in the voltage of the faulty battery cell, which leads to a leakage current I ISC is based on Ohm's law, where increases.

[0075] Next, the duration of the resting process for the normal battery cells (t2-t1) and the duration of the resting process for the faulty battery cells (t12-t11) may be the same.

[0076] Subsequently, in the discharge process, in contrast to the normal battery cells, a part of the discharge power of the faulty battery cell remains unsupplied to the electrical load, resulting in a leakage current I ISC This causes a leakage current I from the faulty battery cell during the discharge process. ISC Since additional discharge power is consumed, the time required for the discharge process t13-t12 for the faulty battery cell is shorter than the time required for the discharge process t3-t2 for the normal battery cell. Also, the difference ΔS2 between the minimum swelling state in the charge process and the minimum swelling state in the discharge process for the faulty battery cell BC is several times to several tens of times larger than the difference ΔS1 between the minimum swelling state in the charge process and the minimum swelling state in the discharge process for the normal battery cell. This is presumably due to the fact that the gas and precipitates generated in the faulty battery cell remain as they are after the discharge process and the exterior material of the faulty battery cell expands due to a temperature rise larger than that of the normal battery cell.

[0077] FIG. 4 is a flowchart illustrating a battery management method according to a first embodiment of the present invention.

[0078] 1 to 4, in step S410, the control circuit 150 generates first time series data of a swelling state of the battery cell BC repeatedly detected during a charging process included in a charge / discharge cycle. In the curve 310, the range of a period t0 to t1 corresponds to the first time series data generated when the battery cell BC is normal. In the curve 320, the range of a period t0 to t11 corresponds to the first time series data generated when the battery cell BC has an internal short circuit failure.

[0079] In step S420, the control circuit 150 determines a first change amount of the swelling state during the charging process from the first time series data. The first change amount may be a difference between a minimum swelling state and a maximum swelling state of the first time series data. Alternatively, the first change amount may be a difference between a swelling state detected at a time when a predetermined time has elapsed from the start of the charging process and a maximum swelling state of the first time series data. In the following, it is assumed that the first change amount is a difference between a minimum swelling state and a maximum swelling state of the first time series data.

[0080] 3, when the battery cell BC is normal, the swelling state at the start time t0 of the charging process is minimum and the swelling state at the end time t1 is maximum, so the first change amount is SA-S0. In contrast, when the battery cell BC is faulty, the swelling state at the start time t0 of the charging process is minimum and the swelling state at the time tP before the end time t11 is maximum, so the first change amount is SP-S0.

[0081] In step S430, the control circuit 150 determines whether the battery cell BC has an internal short circuit failure based on the first change amount. In one example, if the first change amount is equal to or greater than the first critical change amount, the control circuit 150 determines that the battery cell BC has an internal short circuit failure. If the value of step S430 is "YES", the control circuit 150 proceeds to step S440.

[0082] In step S440, the control circuit 150 executes a predetermined protection function. In one example, the control circuit 150 may output an alarm message indicating that the battery cell BC has an internal short circuit fault to the vehicle controller 2 and / or a user (e.g., a driver) through the communication circuit 160. In another example, the control circuit 150 may limit the allowable values ​​of the charging voltage, the discharging voltage, the charging current, and / or the discharging current to a predetermined value.

[0083] The battery management methods according to the second to fourth embodiments described below are modified examples of the battery management method according to the first embodiment described above, and therefore, when describing the embodiments, repeated descriptions of contents common to each other may be omitted.

[0084] FIG. 5 is a flowchart illustrating a battery management method according to a second embodiment of the present invention.

[0085] 1 to 3 and 5, in step S510, the control circuit 150 generates first time-series data of a swelling state of the battery cell BC repeatedly detected during a charging process included in a charge / discharge cycle.

[0086] In step S512, the control circuit 150 generates second time series data of the swelling state of the battery cell BC repeatedly detected during the discharge process included in the charge / discharge cycle. In the curve 310, the range of the period t2 to t3 corresponds to the second time series data generated when the battery cell BC is normal. In the curve 320, the range of the period t12 to t13 corresponds to the first time series data generated when the battery cell BC has an internal short circuit failure.

[0087] In step S520, the control circuit 150 determines a first change amount of the swelling state during the charging process and a second change amount of the swelling state during the discharging process from the first time series data and the second time series data. The second change amount is a difference between the minimum swelling state during the discharging process and the minimum swelling state during the charging process. In FIG. 3, when the battery cell BC is normal, the second change amount is ΔS1. On the other hand, when the battery cell BC is faulty, the second change amount is ΔS2.

[0088] In step S530, the control circuit 150 determines whether the battery cell BC has an internal short circuit failure based on the first change amount and the second change amount.

[0089] In one example, if the first change amount is equal to or greater than the first critical change amount and the second change amount is equal to or greater than the second critical change amount, the battery cell BC is determined to have an internal short circuit failure. In another example, if the sum of the first change amount and the second change amount is equal to or greater than the third critical change amount, the battery cell BC is determined to have an internal short circuit failure. In yet another example, if the weighted sum (or weighted average) of the first change amount and the second change amount is equal to or greater than the fourth critical change amount, the battery cell BC is determined to have an internal short circuit failure. If the value of step S530 is "YES", proceed to step S540.

[0090] In step S540, the control circuit 150 performs a predetermined protection function.

[0091] FIG. 6 is a flowchart illustrating a battery management method according to a third embodiment of the present invention.

[0092] 1 to 3 and 6, in step S610, the control circuit 150 generates first time-series data of a swelling state of the battery cell BC repeatedly detected during a charging process included in a charge / discharge cycle.

[0093] In step S612, the control circuit 150 generates second time-series data of the swelling state of the battery cell BC repeatedly detected during the discharging process included in the charge / discharge cycle.

[0094] In step S620, the control circuit 150 generates third time series data of the battery current of the battery cell BC repeatedly detected during the charging process.

[0095] In step S622, the control circuit 150 generates a fourth time series data of the battery current of the battery cell BC repeatedly detected during the discharging process.

[0096] In step S630, the control circuit 150 determines a first change amount of the swelling state due to the charging process and a second change amount of the swelling state due to the discharging process from the first time series data and the second time series data.

[0097] In step S640, the control circuit 150 determines a first integrated amount of the battery current in the charging process and a second integrated amount of the battery current in the discharging process from the third time series data and the fourth time series data. The first integrated amount indicates an integrated value of the charging current flowing through the battery cell BC from the start to the end of the charging process. The second integrated amount indicates an integrated value of the discharging current flowing through the battery cell BC from the start to the end of the discharging process. The ratio of the second integrated amount to the first integrated amount, i.e., (second integrated amount) / (first integrated amount), indicates the coulombic efficiency of the battery cell BC.

[0098] In step S650, the control circuit 150 determines whether the battery cell BC has an internal short circuit failure based on the first change amount, the second change amount, the first integrated amount, and the second integrated amount.

[0099] In one example, if the first change amount is greater than or equal to the first critical change amount, the second change amount is greater than or equal to the second critical change amount, and the ratio of the second accumulated amount to the first accumulated amount is less than the critical ratio, the battery cell BC is determined to have an internal short circuit fault.

[0100] In another example, when the sum of the first change amount and the second change amount is equal to or greater than the third critical change amount and the ratio of the second accumulated amount to the first accumulated amount is less than the critical ratio, the battery cell BC is determined to have an internal short circuit failure.

[0101] In yet another example, if the weighted sum (or weighted average) of the first and second variations is equal to or greater than the fourth critical variation and the ratio of the second integrated amount to the first integrated amount is less than the critical ratio, the battery cell BC is determined to have an internal short circuit failure. If the value of step S650 is 'YES', proceed to step S660.

[0102] In step S660, the control circuit 150 performs a predetermined protection function.

[0103] FIG. 7 is a flowchart illustrating a battery management method according to a fourth embodiment of the present invention.

[0104] 1 to 3 and 7, in step S710, the control circuit 150 generates first time-series data of a swelling state of the battery cell BC repeatedly detected during a charging process included in a charge / discharge cycle.

[0105] In step S720, the control circuit 150 determines a first change in the swelling state due to the charging process from the first time-series data.

[0106] In step S722, the control circuit 150 determines a first average rate of change of the swelling condition at the beginning of the charging process and a second average rate of change of the swelling condition at the later stage of the charging process from the first time series data.

[0107] The initial stage of the charging process is a period from the start time t0 of the charging process to a time when the first time has elapsed. In the curve 320 of FIG. 3, the initial stage of the charging process is a period from the start time t0 of the charging process to a time tA. The first time may be equal to a product of a reference time of the charging process and a first coefficient (a positive number less than 1). The reference time is a time interval between a time when the minimum swelling state is detected and a time when the maximum swelling state is detected. In one example, when the reference time tP-t0=150 minutes and the first coefficient=0.2, the first time=30 minutes. Alternatively, the first time may be predetermined. The first average rate of change is a value obtained by dividing the amount of change in the initial swelling state (SX-S0) by the first time.

[0108] The later stage of the charging process is the period from the time when the maximum swelling state of the charging process is detected to the second time. In the curve 320 of FIG. 3, the later stage of the charging process is the period from time tB to time tP of the charging process. The second time may be equal to the product of the reference time and the second coefficient (a positive number less than 1). In one example, if the reference time tP-t0=150 minutes and the second coefficient=0.1, then the second time=15 minutes. Alternatively, the second time may be predetermined. The second average rate of change is the amount of change in the swelling state of the later stage (SP-SY) divided by the second time.

[0109] In step S730, the control circuit 150 determines whether the battery cell BC has an internal short circuit failure based on the first change amount, the first average change rate, and the second average change rate.

[0110] In one example, when the first change amount is equal to or greater than the first critical change amount and the ratio of the second average change rate to the first average change rate is less than the critical ratio, the battery cell BC is determined to have an internal short circuit failure.

[0111] In another example, if the first change amount is equal to or greater than the first critical change amount and the difference between the first average change rate and the second average change rate is equal to or greater than the critical change rate, the battery cell BC is determined to have an internal short circuit failure. If the value of step S730 is 'YES', proceed to step S740.

[0112] In step S740, the control circuit 150 performs a predetermined protection function.

[0113] The embodiments of the present invention described above may not necessarily be embodied through an apparatus and method, but may be embodied through a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such implementation should be easily embodied by a person skilled in the art to which the present invention pertains from the description of the above-mentioned embodiments.

[0114] Although the present invention has been described above with reference to limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and various modifications and variations can be made by those having ordinary skill in the art to which the present invention pertains within the scope of the technical spirit of the present invention and the equivalent scope of the claims.

[0115] Furthermore, since the above-mentioned invention can be variously replaced, modified, and altered by a person having ordinary knowledge in the technical field to which the invention belongs without departing from the technical concept of the invention, it is not limited to the above-mentioned embodiments and the attached drawings, and can be configured by selectively combining all or part of each embodiment to make various modifications. [Explanation of symbols]

[0116] 1 Electric vehicles 10 Battery Pack 100 Battery Management System 110 Swelling Detector 150 Control circuit BC Battery Cell BM Battery Module

Claims

1. a swelling detector including at least one sensor for detecting a swelling state of the battery cell; a control circuit for generating first time series data of the swelling state detected repeatedly during a charging process included in a charge / discharge cycle for the battery cell; The control circuit includes: determining a first amount of change in the swelling state due to the charging process from the first time series data; generating second time series data of the swelling state repeatedly detected during a discharging process included in the charge / discharge cycle so as to be performed after the charging process; determining a second amount of change in the swelling state from the first time series data and the second time series data; Determining whether the battery cell has an internal short circuit failure based on the first change amount and the second change amount. Battery management system.

2. A swelling detector including at least one sensor for detecting a swelling state of a battery cell; a control circuit for generating first time series data of the swelling state detected repeatedly during a charging process included in a charge / discharge cycle for the battery cell; The control circuit includes: determining a first amount of change in the swelling state due to the charging process from the first time series data; determining a first average rate of change of the swelling state during an initial period of the charging process and a second average rate of change of the swelling state during a later period of the charging process from the first time series data; determining that the battery cell has an internal short circuit failure based on the first change amount and a ratio of the second average rate of change to the first average rate of change; Battery management system.

3. The swelling state is The battery management system according to claim 1 or 2, wherein the thickness of the battery cell or the load acting on the battery cell is a thickness of the battery cell or a load acting on the battery cell.

4. The control circuit includes:

3. The battery management system according to claim 1, wherein the first change amount is determined to be a difference between a minimum swelling state and a maximum swelling state of the first time series data, or a difference between a swelling state detected at a predetermined time after a start of the charging process and a maximum swelling state of the first time series data.

5. The control circuit includes: A difference between a minimum swelling state of the first time series data and a minimum swelling state of the second time series data is determined as the second amount of change. The battery management system of claim 1 .

6. The control circuit includes: The battery management system according to claim 1 , further comprising: determining that the battery cell has an internal short circuit failure when the first change amount is equal to or greater than a first critical change amount and the second change amount is equal to or greater than a second critical change amount.

7. a current detector configured to detect a battery current flowing through the battery cell; the control circuit generates third time series data of the battery current repeatedly detected during the charging process; generating fourth time series data of the battery current repeatedly detected during the discharging process; determining a first integrated amount of the battery current during the charging process from the third time series data and a second integrated amount of the battery current during the discharging process from the fourth time series data; 2. The battery management system of claim 1, further comprising: determining that the battery cell has an internal short circuit failure when: (i) the first change amount is equal to or greater than a first critical change amount; (ii) the second change amount is equal to or greater than a second critical change amount; and (iii) a ratio of the second integrated amount to the first integrated amount is less than a critical ratio.

8. The control circuit includes:

3. The battery management system of claim 2, further comprising: determining that the battery cell has an internal short circuit failure when (i) the first change amount is equal to or greater than a first critical change amount; and (ii) a ratio of the second average rate of change to the first average rate of change is equal to or greater than a critical ratio.

9. A battery pack comprising the battery management system according to claim 1 or 2.

10. An electric vehicle comprising the battery pack of claim 9.

11. generating first time series data of a swelling state of the battery cell repeatedly detected during a charging process included in a charge / discharge cycle for the battery cell; determining a first change in the swelling state from the first time series data; and generating second time series data of the swelling state repeatedly detected during a discharging process included in the charge / discharge cycle to be performed after the charging process. determining a second amount of change in the swelling state from the first time series data and the second time series data; determining whether the battery cell has an internal short circuit failure based on the first change amount and the second change amount.

12. A step of generating first time series data of a swelling state of a battery cell repeatedly detected during a charging process included in a charge / discharge cycle for the battery cell; determining a first amount of change in the swelling state from the first time series data; determining a first average rate of change of the swelling condition at an early stage of the charging process and a second average rate of change of the swelling condition at a later stage of the charging process from the first time series data; determining that the battery cell has an internal short circuit failure based on the first change amount and a ratio of the second average rate of change to the first average rate of change. Battery management methods.

13. The step of determining a first change in swelling condition comprises:

13. The battery management method according to claim 11, wherein the first change amount is determined to be a difference between a minimum swelling state and a maximum swelling state of the first time series data, or a difference between a swelling state detected at a time when a predetermined time has elapsed from a start point of the charging process and a maximum swelling state of the first time series data.

14. The second change amount is a difference between a minimum swelling state of the first time series data and a minimum swelling state of the second time series data. The battery management method of claim 11.

15. generating third time series data of battery current flowing through the battery cell, the third time series data being repeatedly detected during the charging process; generating fourth time series data of the battery current repeatedly detected during the discharging process; determining a first integrated amount of the battery current during the charging process and a second integrated amount of the battery current during the discharging process from the third time series data and the fourth time series data; The step of determining whether the battery cell has an internal short circuit fault includes:

12. The battery management method of claim 11, further comprising: determining that the battery cell has an internal short circuit failure when: (i) the first change amount is equal to or greater than a first critical change amount; (ii) the second change amount is equal to or greater than a second critical change amount; and (iii) a ratio of the second integrated amount to the first integrated amount is less than a critical ratio.

16. The step of determining whether the battery cell has an internal short circuit fault includes:

13. The battery management method of claim 12, further comprising: determining that the battery cell has an internal short circuit failure when (i) the first change amount is equal to or greater than a first critical change amount, and (ii) a ratio of the second average rate of change to the first average rate of change is equal to or greater than a critical ratio.

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