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

Abstract

A battery management system according to the present invention includes: a sensing circuit for detecting the cell voltage of each of a plurality of battery cells connected in series; and a control circuit for updating first time series data of voltage detection values ​​representing the cell voltage for each battery cell. The control circuit applies a first signal processing algorithm to each battery cell to identify a feature point in the first time series data. The control circuit updates second time series data of cumulative counts representing the total number of times the feature point was identified for each battery cell. The control circuit applies a second signal processing algorithm to each battery cell to determine a trend value of the second time series data. The control circuit detects a local open circuit fault in each battery cell by comparing the trend value with a reference value for each battery cell.

Description

Technology Field

[0001] The present invention relates to a technology for detecting a short circuit in a battery cell. Background Technology

[0003] Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, research on high-performance batteries capable of repeated charging and discharging is actively underway. Currently commercialized batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium batteries.

[0004] A battery pack for applications requiring high capacity and high voltage, such as electric vehicles or energy storage systems, comprises at least one cell group, and each cell group comprises a plurality of battery cells connected in series.

[0005] A battery cell is manufactured by enclosing an electrode assembly together with an electrolyte within an outer casing. The electrode assembly has a structure in which a plurality of positive plates and a plurality of negative plates are stacked and mutually insulated through at least one separator. The battery cell comprises a positive lead and a negative lead. One end of the positive lead is connected to a plurality of positive tabs extending from a plurality of positive plates within the outer casing, and the other end of the positive lead is exposed to the outside of the outer casing as a positive terminal. Similarly, one end of the negative lead is connected to a plurality of negative tabs extending from a plurality of negative plates within the outer casing, and the other end of the negative lead is exposed to the outside of the outer casing as a negative terminal.

[0006] Battery cells gradually age due to various internal and external factors, and open circuit failures can occur due to damage accumulated over a long period or strong impacts occurring in a short period. Open circuit failures can be classified into complete open circuit failures and localized open circuit failures.

[0007] A complete open circuit failure refers to a state in which the current path between the positive and negative terminals of a battery cell is eliminated. For example, this may include cases where the positive lead is broken, the negative lead is broken, all positive tabs are broken, or all negative tabs are broken. In contrast, a local open circuit failure refers to a state in which a current path exists between the positive and negative terminals of a battery cell, but due to microscopic damage to components located inside the casing, the resistance value of the current path may fluctuate irregularly depending on the internal and external conditions of the battery cell. In the case of a complete disconnection failure, the battery cell cannot flow charging and discharging current, whereas in the case of a local disconnection failure, the charging and discharging current can flow. Prior art documents for the present invention include Japanese Published Patent No. 2014-016254 (January 30, 2014), Korean Published Patent No. 10-2021-0054930 (May 14, 2021), and U.S. Published Patent No. 2016-0356856 (December 8, 2016).

[0008] delete Prior art literature

[65535] Japanese Patent Publication No. 2014-016254 (Jan. 30, 2014) Korean Patent Publication No. 10-2021-0054930 (May 14, 2021) U.S. Patent Publication No. 2016-0356856 (Dec. 8, 2016) The problem to be solved

[0009] When at least one battery cell included in the cell group has a complete open circuit failure, the charging and discharging current is cut off, so it is possible to immediately detect that at least one of the battery cells included in the cell group has a complete simple failure.

[0010] However, if a specific battery cell has a local open circuit failure, it is difficult to detect the failure because charge and discharge current can still flow through the cell group.

[0011] The present invention is devised to solve the above-mentioned problems and aims to provide a battery management system, a battery pack, an electric vehicle, and a battery management method that detects a local open circuit fault in each battery cell based on the history of changes over time of the cell voltage of each of a plurality of battery cells detected during charging, discharging, or idle of a cell group.

[0012] Other objects and advantages of the present invention may be understood from the following description and will become more clearly apparent from the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0014] A battery management system according to one aspect of the present invention includes: a sensing circuit configured to detect the cell voltage of each of a plurality of serially connected battery cells; and a control circuit configured to update first time series data of voltage detection values ​​representing the cell voltage for each battery cell. The control circuit is configured to identify a feature point in the first time series data by applying a first signal processing algorithm to each battery cell. The control circuit is configured to update second time series data of cumulative counts representing the total number of times the feature point was identified for each battery cell. The control circuit is configured to determine a trend value of the second time series data by applying a second signal processing algorithm to each battery cell. The control circuit is configured to detect a local open circuit fault of each battery cell by comparing the trend value with a reference value for each battery cell.

[0015] The control circuit above may be configured to identify whether the second voltage detection value is the characteristic point by comparing the first to third voltage detection values, which were most recently added to the first time series data in chronological order for each battery cell.

[0016] The control circuit may be configured to identify, for each battery cell, the second voltage detection value as the characteristic point when, among the first to third voltage detection values ​​recently added to the first time series data in chronological order, the second voltage detection value is greater than the first voltage detection value and the third voltage detection value by a margin value or less than the first voltage detection value and the third voltage detection value by a margin value or less.

[0017] The above trend value may be a scatter plot of the above second time series data.

[0018] The above control circuit may be configured to determine the reference value by adding a threshold value to the average value of the plurality of dispersions of the plurality of battery cells.

[0019] The above trend value may be the slope of the regression line of the above second time series data.

[0020] The above control circuit may be configured to determine the reference value by adding a threshold value to the average value of the plurality of slopes of the plurality of battery cells.

[0021] A battery pack according to another aspect of the present invention includes the battery management system.

[0022] An electric vehicle according to another aspect of the present invention includes the battery pack.

[0023] A battery management method according to another aspect of the present invention comprises: a step of detecting the cell voltage of each of a plurality of battery cells connected in series; a step of updating a first time series data of voltage detection values ​​representing the cell voltage for each battery cell; and a step of detecting a local open circuit fault of each battery cell. The step of detecting a local open circuit fault of each battery cell comprises: a step of identifying a feature point in the first time series data by applying a first signal processing algorithm; a step of updating a second time series data of cumulative counts representing the total number of times the feature point was identified; a step of determining a trend value of the second time series data by applying a second signal processing algorithm; and a step of detecting the local open circuit fault by comparing the trend value with a reference value. Effects of the invention

[0025] According to at least one embodiment of the present invention, a local open circuit failure of each battery cell can be detected based on the history of changes over time of the cell voltage of each of a plurality of battery cells detected during charging, discharging, or resting of a cell group.

[0026] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a diagram illustrating the configuration of an electric vehicle according to the present invention in an exemplary manner. Figure 2 is a diagram exemplarily showing the structure of a battery cell illustrated in Figure 1. Figure 3 is a diagram referenced to explain a local open circuit failure of a battery cell illustrated in Figure 2. Figure 4 is a diagram representing the electrode assembly of the battery cell of Figure 2 as an equivalent circuit in which a plurality of unit cells are connected in parallel. Figure 5 is a graph exemplifying the change in cell voltage over time of a faulty battery cell. Figure 6 is a figure referenced to explain the time series of accumulated counts used to detect local open circuit failures in battery cells. FIG. 7 is a flowchart illustrating an exemplary battery management method according to a first embodiment of the present invention. FIG. 8 is a flowchart exemplarily illustrating a battery management method according to a second embodiment of the present invention. Specific details for implementing the invention

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0030] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0031] Terms including ordinal numbers, such as first, second, etc., are used for the purpose of distinguishing one of the various components from the rest, and are not used to limit the components by such terms.

[0032] Throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "<unit>" as used in the specification refer to a unit that performs at least one function or operation and may be implemented in hardware, software, or a combination of hardware and software.

[0033] Additionally, throughout the specification, when it is said that a part is "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other components in between.

[0034] FIG. 1 is a diagram illustrating the configuration of an electric vehicle according to the present invention in an exemplary manner.

[0035] Referring to FIG. 1, the electric vehicle (1) includes a vehicle controller (2), a battery pack (10), and an electric load (30). The charging and discharging terminals (P+, P-) of the battery pack (10) can be electrically connected to a charger (3) via a charging cable or the like. The charger (3) may be included in the electric vehicle (1) or provided at a charging station.

[0036] A vehicle controller (2) (e.g., ECU: Electronic Control Unit) is configured to transmit a key-on signal to a battery management system (100) in response to a user switching a start button (not shown) provided in an electric vehicle (1) to the ON position. The vehicle controller (2) is configured to transmit a key-off signal to a battery management system (100) in response to a user switching the start button to the OFF position. A charger (3) can communicate with the vehicle controller (2) to supply charging power of a constant current or constant voltage through the charging / discharging terminals (P+, P-) of the battery pack (10).

[0037] The battery pack (10) includes a cell group (CG), a relay (20), and a battery management system (100).

[0038] The cell group (CG) comprises a plurality of battery cells (BC1~BC N , N It includes (a natural number greater than or equal to 2) and may also be referred to as a 'battery module'. Multiple battery cells (BC1~BC N ) are connected in series with each other. Multiple battery cells (BC1~BC N , where N is a natural number greater than or equal to 2, may be manufactured to have identical electrochemical specifications. In the following description, a plurality of battery cells (BC1~BC N In explaining the common content of ), the code 'BC' was assigned to the battery cell.

[0039] The battery cell (BC) is not particularly limited in type as long as it is capable of repeated charging and discharging, such as a lithium-ion cell.

[0040] The relay (20) is electrically connected in series to the cell group (CG) through a power path connecting the cell group (CG) and the inverter (31). In FIG. 1, the relay (20) is illustrated as being connected between the positive terminal and the charge / discharge terminal (P+) of the cell group (CG). The relay (20) is turned on / 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 / off by the magnetic force of a coil, or a semiconductor switch such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0041] The electric load (30) includes an inverter (31) and an electric motor (32). The inverter (31) is provided to convert direct current from a group of cells (CG) included in a battery pack (10) into alternating current in response to a command from a battery management system (100) or a vehicle controller (2). The electric motor (32) is driven using alternating power from the inverter (31). For example, a three-phase alternating motor may be used as the electric motor (32).

[0042] The battery management system (100) includes a sensing circuit (110) and a control circuit (160). The battery management system (100) may further include a communication circuit (170).

[0043] The sensing circuit (110) is configured to acquire state parameters of the battery cell (BC). The state parameters of the battery cell (BC) include the voltage, current, and / or temperature of the battery cell (BC). The sensing circuit (110) includes a voltage detector (120). The sensing circuit (110) may further include at least one of a current detector (130), a temperature detector (140), and a motion detector (150).

[0044] The voltage detector (120) comprises a plurality of battery cells (BC1~BC) included in the cell group (CG). N ) connected to the respective positive and negative terminals, the cell voltage (V1~V) which is the voltage across both ends of the battery cell (BC). N Detects ) and the detected cell voltage (V1~V N It is configured to generate a voltage signal representing ).

[0045] A current detector (130) is connected in series to a cell group (CG) through a current path between the cell group (CG) and the inverter (31). The current detector (130) is configured to detect the charge / discharge current flowing through the cell group (CG) and to generate a current signal indicating the detected charge / discharge current. A plurality of battery cells (BC1~BC NSince ) are connected in series, multiple battery cells (BC1~BC N A common charge / discharge current flows through it. The current detector (130) can be implemented with one or more combinations of known current detection elements, such as a shunt resistor, a Hall effect element, etc.

[0046] A temperature detector (140) is configured to detect the battery temperature, which is the temperature of a cell group (CG), and to generate a temperature signal indicating the detected battery temperature. The temperature detector (140) may be positioned within a predetermined distance from the cell group (CG) so as to detect a temperature close to the actual temperature of the cell group (CG). For example, the temperature detector (140) may be attached to the surface of at least one battery cell (BC) included in the cell group (CG) and may detect the surface temperature of the battery cell (BC) as the battery temperature. The temperature detector (140) may be implemented as one or more combinations of known temperature detection elements, such as a thermocouple, a thermistor, a bimetal, etc.

[0047] The motion detector (150) is configured to detect movement (e.g., shaking, displacement) of a cell group (CG) and to generate a motion signal indicating the intensity of the detected movement. The motion signal depends on both internal conditions of the cell group (CG) (e.g., swelling of battery cells) and external conditions (e.g., driving conditions of the electric vehicle). The motion detector (150) may be implemented with one or more combinations of known motion detection elements, such as an acceleration sensor, a displacement sensor, a pressure sensor, etc.

[0048] The communication circuit (170) is configured to support wired or wireless communication between the control circuit (160) and the vehicle controller (2). Wired communication may be, for example, CAN (controller area network) communication, and wireless communication may be, for example, Zigbee or Bluetooth communication. Of course, as long as it supports wired or wireless communication between the control circuit (160) and the vehicle controller (2), the type of communication protocol is not particularly limited. The communication circuit (170) may include an output device (e.g., display, speaker) that provides information received from the control circuit (160) and / or the vehicle controller (2) in a form recognizable by the user (driver).

[0049] The control circuit (160) is operably coupled to the relay (20), the sensing circuit (110), and the communication circuit (170). Being operably coupled means that the two components are directly or indirectly connected so that signals can be transmitted and received in either a unidirectional or bidirectional manner.

[0050] The control circuit (160) can collect a voltage signal from the voltage detector (120), a current signal from the current detector (130), a temperature signal from the temperature detector (140), and / or a motion signal from the motion detector (150) at regular intervals during charging, discharging, and / or resting of the cell group (CG). That is, the control circuit (160) can acquire a voltage detection value, a current detection value, a temperature detection value, and a motion detection value from the analog signals collected from the detectors (120, 130, 140, 150) using an internally provided ADC (Analog to Digital Converter) and record them in the memory (161).

[0051] The control circuit (160) can be referred to as a ‘battery controller’ and can be implemented in hardware using at least one of ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), microprocessors, and other electrical units for performing functions.

[0052] The memory (161) may include at least one type of storage medium among, for example, a flash memory type, a hard disk type, an SSD type (Solid State Disk type), an SSD type (Silicon Disk Drive type), a multimedia card micro type, RAM (random access memory; RAM), SRAM (static random access memory), ROM (read-only memory; ROM), EEPROM (electrically erasable programmable read-only memory), and PROM (programmable read-only memory). The memory (161) may store data and programs required for computational operations by the control circuit (160). The memory (161) may store data representing the results of computational operations by the control circuit (160). The memory (161) may store various algorithms applied to the detection of local open circuit failures of the battery cell (BC). The memory (161) may be integrated within the control circuit (160).

[0053] When the relay (20) is turned on during the operation of the electric load (30) and / or charger (3), the cell group (CG) becomes a charging mode or a discharging mode. When the relay (20) is turned off while the cell group (CG) is in use in the charging mode or the discharging mode, the cell group (CG) switches to a resting mode.

[0054] The control circuit (160) can turn on the relay (20) in response to a key-on signal. The control circuit (160) can turn off the relay (20) in response to a key-off signal. The key-on signal is a signal requesting a transition from idle to charging or discharging. The key-off signal is a signal requesting a transition from charging or discharging to idle. Alternatively, the on / off control of the relay (20) can be handled by the vehicle controller (2) instead of the control circuit (160).

[0055] The control circuit (160) is configured such that, during the charging of the battery pack (10), a plurality of battery cells (BC1~BC N By monitoring the voltage of each individual, multiple battery cells (BC1~BC N The maximum voltage of ) can be identified. The maximum voltage is a plurality of battery cells (BC1~BC N It is the maximum among the voltages of ).

[0056] The control circuit (160) is configured such that, during the discharge of the battery pack (10), a plurality of battery cells (BC1~BC N By monitoring the voltage of each, the minimum voltage can be identified. The minimum voltage is the voltage of multiple battery cells (BC1~BC N It is the minimum among the voltages of ).

[0057] The control circuit (160) is configured such that, during the charging of the battery pack (10), a plurality of battery cells (BC1~BC N When the maximum voltage of ) reaches a predetermined upper limit voltage (e.g., 4.25 V[volt]), charging of the battery pack (10) can be stopped.

[0058] The control circuit (160) is a plurality of battery cells (BC1~BC) during the discharge of the battery pack (10). N When the minimum voltage of ) reaches a predetermined lower limit voltage (e.g., 3.20 V), the discharge of the battery pack (10) can be stopped.

[0059] FIG. 2 is a diagram exemplarily showing the structure of a battery cell illustrated in FIG. 1, FIG. 3 is a diagram referenced to explain a local open circuit failure of the battery cell illustrated in FIG. 2, and FIG. 4 is a diagram representing the electrode assembly of the battery cell of FIG. 2 as an equivalent circuit in which a plurality of unit cells are connected in parallel. The structure of the battery cell illustrated in FIG. 2 is merely an example, and it should be understood that various other structures may be applied.

[0060] Referring to FIG. 2, the battery cell (BC) includes an electrode assembly (200), a positive lead (210), a negative lead (220), and an outer casing (230).

[0061] The electrode assembly (200) includes a plurality of positive plates (201), a plurality of negative plates (202), and at least one separator (203). Within the electrode assembly, the plurality of positive plates and the plurality of negative plates may be arranged to be mutually insulated by at least one separator (203).

[0062] Each of the plurality of positive plates (201) has a positive tab (205) which is a portion formed protruding therefrom, and each of the plurality of negative plates (202) has a negative tab (206) which is a portion formed protruding therefrom. The positive tabs (205) are coupled to one end of the positive lead (210), and the negative tabs (206) are coupled to one end of the negative lead (210).

[0063] The electrode assembly (200) is housed within an outer casing (230) together with an electrolyte, with positive tabs (205) and negative tabs (206) coupled to one end of each positive lead (210) and negative lead (220). Accordingly, the other end of each positive lead (210) and negative lead (220) exposed to the outside of the outer casing (230) is provided as the positive terminal and negative terminal of the battery cell (BC).

[0064] FIG. 3 is an enlarged view of area (A) of FIG. 2, where area (A) illustrates damaged areas (401, 402, 403) on the positive lead (210) caused by tearing or the like. Since the damaged areas (401, 402, 403) obstruct the flow of charging and discharging current, the resistance value of the positive lead (210) increases compared to the normal state without damaged areas. When the battery cell (BC) is being charged or discharged, or when an external force is applied to the battery cell (BC), irregular deformation is induced in the damaged areas (401, 402, 403). Consequently, the resistance value of the positive lead (210), which depends on the size and location of the damaged areas (401, 402, 403) of the positive lead (210), also fluctuates irregularly. Although FIG. 3 describes an example in which the positive lead (210) is damaged, the same description applies to the negative lead (220), positive tabs (205) and / or negative tabs (206).

[0065] Referring to FIG. 4, if a pair of one positive plate (201) and one negative plate (202) insulated by a separator (230) is defined as a 'unit cell (UC)', then the battery cell (BC) comprises a plurality of unit cells (UC1~UC) between the positive lead (210) and the negative lead (220). M , M) can be equivalent to a circuit in which 2 or more natural numbers are connected in parallel.

[0066] In FIG. 4, assuming j is a natural number from 1 to M, the resistance (RT j ) is a unit cell (UC jThe total resistance value of the positive tab (205) and negative tab (206) included in ) is represented by resistance (RL), which represents the total resistance value of the positive lead (210) and negative lead (220). Resistance (RT j The resistance value of ) is the unit cell (UC j It depends on the degree of local open circuit failure present in the positive tab (205) and / or negative tab (206) included in ). The resistance value of resistor (RL) depends on the degree of local open circuit failure present in the positive lead (210) and / or negative lead (220). Resistance (RT j Each of the ) and the resistor (RL) can be described as an uncontrollable variable resistor in that its resistance value fluctuates irregularly depending on the internal and external environment of the battery cell (BC).

[0067] FIG. 5 is a graph exemplifying the change in cell voltage of a faulty battery cell over time, and FIG. 6 is a diagram referenced to explain the time series of accumulated counts used to detect a local open circuit fault in a battery cell. For convenience of explanation, FIG. 5 assumes that the battery cell (BC1) has a local open circuit fault.

[0068] The control circuit (160) can acquire the cell voltage of a battery cell (BC) at a predetermined detection cycle (e.g., 0.1 seconds) using a voltage detector (120) during the charging, discharging, and / or resting of the cell group (CG). Additionally, the control circuit (160) can acquire the charge / discharge current of the cell group (CG) at the same timing as the cell voltage detection timing using a current detector (130) during the charging, discharging, and / or resting of the cell group (CG). The control circuit (160) can record the voltage detection value of the cell voltage of the battery cell (BC) and the current detection value of the charge / discharge current of the cell group (CG) acquired at each detection timing in a memory (161). Additionally, the control circuit (160) can update the voltage time series data (which may be referred to as the 'first time series data') of the cell voltage of the battery cell (BC) using the newly acquired voltage detection value and current detection value at each detection timing of the sensing circuit (110). Along with this, reference time series data of motion detection values ​​representing the movement history of the cell group (CG) can be additionally updated. The time series data of motion detection values ​​may include motion detection values ​​sequentially acquired by the motion detector (150) over a period common to the voltage time series data. Time series data of other parameters of the cell group (CG) (e.g., charge / discharge current, temperature) can also be updated in synchronization with other time series data.

[0069] In FIG. 5, curve (510) illustrates the change in charge / discharge current of a cell group (CG) over time, and curve (520) illustrates the change in cell voltage of a faulty battery cell (BC1) over time. The period from time tA to tB is the charging period, and the period from time tB to tC is the discharging period. Hereinafter, it is assumed that time tC is the current time and time tA is before time tC.

[0070] The control circuit (160) includes voltage detection values ​​of the cell voltage acquired over a target period with the current time point tC as the end point, such that the voltage time series data of the battery cell (BC) is the target period. The target period may have a start point that is a predetermined time (e.g., 1 day) earlier than the end point. Alternatively, the start point of the target period may be the manufacturing time of the battery pack (10). Alternatively, the start point of the target period may be the most recent time when the cell group (CG) is switched to charging or discharging while remaining in a resting state for a predetermined time or longer. The control circuit (160) may remove voltage detection values ​​acquired before the start point of the target period from the memory (161).

[0071] The control circuit (160) can identify feature points in the voltage time series data by applying a first signal processing algorithm to the voltage time series data whenever the voltage time series data of the battery cell (BC) is updated. The first signal processing algorithm may include a peak detection algorithm. The peak detection algorithm detects local maximum and / or local minimum values ​​appearing on the curve (520) as feature points.

[0072] The control circuit (160) can identify whether the second voltage detection value is a feature point by comparing the first to third voltage detection values, which were recently added to the voltage time series data in chronological order. When the detection period of the cell voltage and charge / discharge current is Δt and the third voltage detection value is the cell voltage acquired at time point t, the second voltage detection value represents the cell voltage acquired at time point t-Δt, and the first voltage detection value represents the cell voltage acquired at time point t-2Δt. The control circuit (160) can identify the second voltage detection value as a feature point for the battery cell (BC) if (i) the second voltage detection value is greater than the first voltage detection value and the third voltage detection value by a margin value or (ii) the second voltage detection value is smaller than the first voltage detection value and the third voltage detection value by a margin value. The margin value can be predetermined by considering the precision of the voltage detection (e.g., the resolution of the ADC), noise, etc.

[0073] The cell voltage of a normal battery cell (BC) continuously increases during charging and continuously decreases during discharging. On the other hand, the cell voltage of a faulty battery cell (BC1) may temporarily decrease during charging and may temporarily increase during discharging. Accordingly, the control circuit (160) can identify whether the voltage detection value obtained during charging is a local minimum value and whether the voltage detection value obtained during discharging is a local maximum value.

[0074] In FIG. 5, the points marked 'X' are local maximum values ​​identified from the curve (520), and the points marked 'Y' are local minimum values ​​identified from the curve (520). The control circuit (160) comprises a plurality of battery cells (BC1~BC N For each of the above, whenever the voltage time series data is updated, a time series data (which may be referred to as 'second time series data') is updated, which includes cumulative counts representing the total number of times feature points are identified from the voltage time series data.

[0075] FIG. 6 is an example of second time series data of a faulty battery cell (BC1) associated with the curve (520) of FIG. 5. Time point t0 is the start time of the target period, and the cumulative count at time point t0 is exemplified as 0. Time point tA is the time during charging, and since no feature point was identified at time point tA, the cumulative count at time point tA is K, which is the same as the previous timing (tA-Δt). For reference, K represents the number of times a feature point was identified between time point t0 and time point tA-Δt.

[0076] Time points t1, t2, and t3 are times when a local minimum (Y) is identified during charging, respectively, and the cumulative counts at time points t1, t2, and t3 are K+1, K+2, and K+3, respectively, which are increased by 1 compared to the previous timing. Time points t4 and t5 are times when a local maximum (X) is identified during discharging, and the cumulative counts at time points t4 and t5 are K+4 and K+5, respectively, which are recorded as values ​​increased by 1 compared to the previous timing.

[0077] Compared to a normal battery cell, the faulty battery cell (BC1) has a larger number of voltage detection values ​​identified as local minimums and / or local maximums during charging, discharging, or resting. Therefore, over a common target period, the dispersion and / or slope (rate of increase) of the cumulative counts included in the second time series data of the faulty battery cell (BC1) is greater than that of the normal battery cell.

[0078] The control circuit (160) comprises a plurality of battery cells (BC1~BC N For each of the above, the second time series data is updated whenever the first time series data is updated. Then, the control circuit (160) updates the second time series data whenever the first time series data is updated. NA second signal processing algorithm can be applied to each second time series data to determine a trend value, which is information related to a local open-circuit fault, from each second time series data. The second signal processing algorithm may include at least one algorithm for extracting trend information of data points included therein from the second time series data, such as a scatter plot calculation algorithm, a linear regression algorithm, a weighted average algorithm, and / or a double exponential smoothing algorithm. The trend value may be the scatter plot (e.g., variance, standard deviation) of the cumulative counts included in the second time series data. Alternatively, the trend value may be the slope of the regression line of the second time series data. The regression line of the second time series data is the result of applying linear regression processing (e.g., least squares method) to the cumulative counts included in the second time series data.

[0079] The reference value may be predetermined as a constant.

[0080] Alternatively, the control circuit (160) comprises a plurality of battery cells (BC1~BC N A reference value can be determined by adding a threshold value to the average value of multiple trend values ​​determined to be one-to-one associated with ). The threshold value may be a value predetermined as a constant.

[0081] Alternatively, the control circuit (160) may determine a reference value based on reference time series data. For example, the control circuit (160) may determine a reference value by multiplying the average of the motion detection values ​​included in the reference time series data by a predetermined weight. In this regard, the greater and more frequently the movement of the cell group (CG) fluctuates during the target period, the greater the total number of times a feature point is identified from the first time series data of the faulty battery cell (BC1). Therefore, by determining a reference value to have a positive correlation with the average of the motion detection values, local open circuit failures can be detected more precisely.

[0082] The control circuit (160) comprises a plurality of battery cells (BC1~BCN For each of the following, a local open circuit fault of a battery cell (BC) can be detected by comparing the trend value of the second time series data with a reference value. For example, a plurality of battery cells (BC1~BC N Among them, each battery cell (BC) associated with a trend value greater than the reference value is detected as having a local open circuit failure.

[0083] FIG. 7 is a flowchart illustrating an exemplary battery management method according to a first embodiment of the present invention.

[0084] Referring to FIGS. 1 to 7, in step S700, the control circuit (160) comprises a plurality of battery cells (BC1 to BC N ) Detects the voltage of each cell. That is, multiple battery cells (BC1~BC N ) The latest voltage detection values ​​representing each cell voltage are obtained. In step S700, in addition to the cell voltage, at least one detection value among the charge / discharge current, temperature, and movement of the cell group (CG) may be additionally obtained.

[0085] In step S710, the control circuit (160) updates the first time series data of voltage detection values ​​representing the cell voltage for each battery cell (BC). When i is a natural number from 1 to N, the battery cell (BC i The first time series data updated for ) is a battery cell (BC) at regular intervals (Δt) from the start to the end of the target period. i It is a set of voltage detection values ​​listed in the order obtained from ).

[0086] In step S720, the control circuit (160) detects a local open circuit fault in each battery cell (BC). Step S720 includes steps S722, S724, S726, and S728.

[0087] In step S722, the control circuit (160) applies a first signal processing algorithm to the first time series data of each battery cell (BC) to identify feature points (e.g., local maximums and / or local minimums) in the first time series data of each battery cell (BC).

[0088] In step S724, the control circuit (160) updates the second time series data of accumulated counts representing the total number of times feature points are identified from the first time series data of each battery cell (BC).

[0089] In step S726, the control circuit (160) applies a second signal processing algorithm to the second time series data of each battery cell (BC) to determine the trend value of the second time series data of each battery cell (BC).

[0090] In step S728, the control circuit (160) determines whether the trend value of each battery cell (BC) is greater than a reference value. If the value of step S728 is "Yes," it indicates that a local open circuit fault of the corresponding battery cell (BC) has been detected. If the value of step S728 is "Yes," the process proceeds to step S730.

[0091] In step S730, the control circuit (160) performs a predetermined protection function. For example, the control circuit (160) may output an alarm message containing identification information of each battery cell (BC) in which a local open circuit fault has been detected to the vehicle controller (2) and / or user (e.g., driver) via the communication circuit (160). For another example, the control circuit (160) may limit the allowable value of the charging voltage and / or charging current to a predetermined value, or limit the allowable value of the discharge voltage and / or discharge current to a predetermined value.

[0092] FIG. 8 is a flowchart illustrating an exemplary battery management method according to a second embodiment of the present invention. In describing the second embodiment, repetitive descriptions of contents common to the first embodiment will be omitted.

[0093] Referring to FIGS. 1 to 6 and FIG. 8, in step S800, the control circuit (160) comprises a plurality of battery cells (BC1 to BC N ) Detects the movement of each cell voltage and cell group (CG). In step S800, at least one detection value among the charge / discharge current and temperature of the cell group (CG) may be additionally acquired.

[0094] In step S810, the control circuit (160) updates the first time series data of voltage detection values ​​representing the cell voltage for each battery cell (BC).

[0095] In step S812, the control circuit (160) updates the reference time series data of motion detection values ​​representing the movement of the cell group (CG).

[0096] In step S820, the control circuit (160) detects a local open circuit fault in each battery cell (BC). Step S820 includes steps S822, S824, S826, and S828.

[0097] In step S822, the control circuit (160) applies a first signal processing algorithm to the first time series data of each battery cell (BC) to identify feature points in the first time series data of each battery cell (BC).

[0098] In step S824, the control circuit (160) updates the second time series data of accumulated counts representing the total number of times feature points are identified from the first time series data of each battery cell (BC).

[0099] In step S826, the control circuit (160) applies a second signal processing algorithm to the second time series data of each battery cell (BC) to determine the trend value of the second time series data.

[0100] In step S827, the control circuit (160) determines a reference value based on reference time series data.

[0101] In step S828, the control circuit (160) determines whether the trend value of each battery cell (BC) is greater than a reference value. If the value of step S828 is "Yes," it indicates that a local open circuit fault of the corresponding battery cell (BC) has been detected. If the value of step S828 is "Yes," the process proceeds to step S840.

[0102] In step S830, the control circuit (160) performs a predetermined protection function.

[0103] The embodiments of the present invention described above are not limited to implementation through devices and methods, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments of the present invention or a recording medium on which such a program is recorded. Such implementation can be easily achieved by a person skilled in the art to which the present invention pertains, based on the description of the embodiments described above.

[0104] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0105] Furthermore, since the present invention described above allows for various substitutions, modifications, and changes within the scope of the technical concept of the present invention to those skilled in the art without departing from the technical spirit of the present invention, it is not limited by the aforementioned embodiments and attached drawings, but rather all or part of each embodiment may be selectively combined to allow for various modifications. Explanation of the symbols

[0107] 1: Electric vehicle 10: Battery pack CG: Cell group BC: Battery cell 100: Battery Management System 110: Sensing circuit 160: Control circuit

Claims

Claim 1 A battery management system comprising: a sensing circuit configured to detect the cell voltage of each of a plurality of serially connected battery cells; and a control circuit configured to update first time series data of voltage detection values ​​representing the cell voltage for each battery cell, wherein the control circuit applies a first signal processing algorithm to each battery cell to identify a feature point representing a local maximum or local minimum value in the first time series data, updates second time series data of cumulative counts representing the total number of times the feature point is identified, applies a second signal processing algorithm to determine a trend value of the second time series data, and compares the trend value with a reference value to detect a local open circuit fault of each battery cell. Claim 2 A battery management system according to claim 1, wherein the control circuit is configured to identify whether the second voltage detection value is the characteristic point by comparing the first to third voltage detection values, which are most recently added to the first time series data in chronological order for each battery cell. Claim 3 A battery management system according to paragraph 2, wherein the control circuit is configured to identify, for each battery cell, the second voltage detection value as the characteristic point when, among the first to third voltage detection values ​​recently added in chronological order to the first time series data, the second voltage detection value is greater than the first voltage detection value and the third voltage detection value by a margin value or when the second voltage detection value is smaller than the first voltage detection value and the third voltage detection value by a margin value or more. Claim 4 In claim 1, the trend value is a scatter plot of the second time series data, a battery management system. Claim 5 In paragraph 4, the control circuit is configured to determine the reference value by adding a threshold value to the average value of the plurality of dispersions of the plurality of battery cells. Claim 6 A battery management system according to claim 1, wherein the trend value is the slope of the regression line of the second time series data. Claim 7 In claim 6, the control circuit is configured to determine the reference value by adding a threshold value to the average value of the slopes of the plurality of battery cells. Claim 8 A battery pack comprising the battery management system according to any one of claims 1 to 7. Claim 9 An electric vehicle comprising the above battery pack according to paragraph 8. Claim 10 A battery management method comprising: a sensing circuit detecting the cell voltage of each of a plurality of serially connected battery cells; a control circuit updating first time series data of voltage detection values ​​representing the cell voltage for each battery cell; and the control circuit detecting a local open circuit fault of each battery cell, wherein the step of detecting a local open circuit fault of each battery cell comprises: the control circuit applying a first signal processing algorithm to identify a feature point representing a local maximum value or a local minimum value in the first time series data; the control circuit updating second time series data of cumulative counts representing the total number of times the feature point was identified; the control circuit applying a second signal processing algorithm to determine a trend value of the second time series data; and the control circuit comparing the trend value with a reference value to detect the local open circuit fault. Claim 11 A computer-readable storage medium storing a program for executing the battery management method of paragraph 10 on a computer.

Images