Apparatus and method for diagnosing battery, and battery pack

Abstract

The present disclosure relates to an apparatus and a method for diagnosing a battery, and a battery pack. The technical problem is to be solved by providing a method in which an internal short circuit of a battery cell can be accurately detected without being affected by individual battery cell voltage deviation that may be caused by the SOH of each battery cell during a charging process. To this end, the present disclosure provides a configuration in which a diagnosis voltage is determined by compensating for a cell voltage of a target battery cell through a compensation voltage for compensating for a low voltage increase rate of the target battery cell having a high SOH, and then an internal short circuit of the target battery cell is diagnosed through the determined diagnosis voltage.

Description

Battery diagnostic device and method, battery pack

[0001] The present disclosure relates to a battery diagnostic device and method, and a battery pack.

[0002]

[0003] Unlike primary batteries, which cannot be recharged, secondary batteries are batteries capable of both charging and discharging. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptop computers, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for motor drive systems and for power storage in hybrid and electric vehicles. Such secondary batteries (i.e., battery cells) include an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes; a case housing the electrode assembly; and electrode terminals electrically connected to the electrode assembly. Charging and discharging of the battery cell are performed by injecting an electrolyte into the battery cell case and allowing an electrochemical reaction to occur between the positive electrode, the negative electrode, and the electrolyte solution. The battery cell case can be implemented in various shapes, such as cylindrical or rectangular, depending on the application of the battery cell.

[0004] In battery cells, an internal short circuit can occur due to the loss of function of the separator, causing the positive and negative electrodes inside the cell to short-circuit. Internal short circuits in battery cells can be caused by deformation due to external impact, metallic foreign substances introduced during the manufacturing process, or the formation of lithium or copper dendrites due to electrochemical reactions. Such internal short circuits in battery cells can lead to safety issues, such as thermal runaway.

[0005] Furthermore, in the case of secondary batteries applied to large-capacity systems such as electric vehicles or Energy Storage Systems (ESS), long lifespan, high output characteristics, and safety are required due to the characteristics of large-capacity systems. In particular, in the case of batteries in which abnormal metallic foreign matter or scrap-type foreign matter containing substrates has entered, lithium salts may grow around the area of ​​foreign matter entry and penetrate the separator under pressurized conditions where cell swelling is restricted by an external barrier, and consequently, there is a risk of thermal runaway caused by an internal short circuit of the battery cell.

[0006] The information described above disclosed in the background technology of this invention is intended only to enhance understanding of the background of the present invention and may therefore include information that does not constitute prior art.

[0007]

[0008] The present invention aims to provide a battery diagnostic device, a method, and a battery pack capable of detecting an internal short circuit in a battery cell caused by lithium salt precipitation that may occur in a lithium-ion battery during the charging process, while accurately detecting the internal short circuit without being affected by cell voltage deviations of each battery cell that may be caused by the SOH of each battery cell during the charging process.

[0009] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems can be clearly understood by those skilled in the art from the description of the invention below.

[0010]

[0011] A battery diagnostic device according to an embodiment of the present invention for solving the above technical problem comprises: a memory storing the State of Health (SOH) of each of a plurality of battery cells; and a processor diagnosing an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells obtained during the charging process of the plurality of battery cells. The processor is characterized by determining, based on the SOH stored in the memory, a target battery cell having a lower voltage rise rate compared to other battery cells during the charging of the plurality of battery cells, determining a compensation voltage to compensate for the lower voltage rise rate of the target battery cell, determining a diagnostic voltage by compensating the target cell voltage of the target battery cell through the determined compensation voltage, and then diagnosing an internal short circuit of the target battery cell through the determined diagnostic voltage.

[0012] The above processor can diagnose an internal short circuit of any one battery cell by determining whether the cell voltage of any one battery cell is lower than a preset threshold compared to a reference voltage determined based on the cell voltages of each of the plurality of battery cells.

[0013] The processor may determine as the target battery cell one battery cell having the maximum SOH among the plurality of SOHs, or the first to Nth battery cells each having the first to Nth SOHs based on the order of increasing SOH.

[0014] The above processor can determine the compensation voltage based on the product of the representative cell voltage of a representative battery cell having a representative SOH corresponding to a statistical representative value among the plurality of SOHs, and the SOH ratio factor based on the ratio of the target SOH of the target battery cell to the representative SOH of the representative battery cell.

[0015] The above statistical representative value may be the median or the mean.

[0016] The above SOH ratio factor may be a value obtained by subtracting 1 from the ratio of the target SOH to the representative SOH.

[0017] The processor determines the compensation voltage based on the product of the representative cell voltage, the SOH ratio factor, and the deviation compensation factor, wherein the deviation compensation factor may be a factor for actively compensating for the deviation between the representative cell voltage and the target cell voltage that increases as charging proceeds due to the low voltage rise rate of the target battery cell, depending on the time when the target cell voltage is compensated.

[0018] The above deviation compensation factor may be the State of Charge (SOC) of the target battery cell at the time when the target cell voltage is compensated.

[0019] The above processor can determine the diagnostic voltage as the sum of the target cell voltage and the compensation voltage.

[0020] A battery diagnostic method according to an embodiment of the present invention comprises: a step in which a processor initiates charging of a plurality of battery cells; a step in which the processor determines a target battery cell having a lower voltage rise rate compared to other battery cells based on the SOH of each of the plurality of battery cells; a step in which the processor determines a compensation voltage to compensate for the lower voltage rise rate of the target battery cell; a step in which the processor determines a diagnostic voltage by compensating the target cell voltage of the target battery cell through the determined compensation voltage; and a step in which the processor diagnoses an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells, wherein for the target battery cell, the internal short circuit of the target battery cell is diagnosed using the determined diagnostic voltage.

[0021] In the step of diagnosing the internal short circuit, the processor can diagnose the internal short circuit of any one battery cell by determining whether the cell voltage of any one battery cell is lower than a preset threshold value relative to a reference voltage determined based on the cell voltages of each of the plurality of battery cells.

[0022] In the step of determining the target battery cell, the processor may determine as the target battery cell one battery cell having the maximum SOH among the plurality of SOHs, or first to Nth battery cells each having a first to Nth SOH based on the order of increasing SOH.

[0023] In the step of determining the compensation voltage, the processor may determine the compensation voltage based on the product of the representative cell voltage of a representative battery cell having a representative SOH corresponding to a statistical representative value among the plurality of SOHs, and the SOH ratio factor based on the ratio of the target SOH of the target battery cell to the representative SOH of the representative battery cell.

[0024] The above statistical representative value may be the median or the mean.

[0025] The above SOH ratio factor may be a value obtained by subtracting 1 from the ratio of the target SOH to the representative SOH.

[0026] In the step of determining the compensation voltage, the processor determines the compensation voltage based on the product of the representative cell voltage, the SOH ratio factor, and the deviation compensation factor, wherein the deviation compensation factor may be a factor for actively compensating for the deviation between the representative cell voltage and the target cell voltage that increases as charging proceeds due to the low voltage rise rate of the target battery cell, depending on the time when the target cell voltage is compensated.

[0027] The above deviation compensation factor may be the State of Charge (SOC) of the target battery cell at the time when the target cell voltage is compensated.

[0028] In the step of determining the above diagnostic voltage, the processor may determine the diagnostic voltage as the sum of the target cell voltage and the compensation voltage.

[0029] A battery pack according to one embodiment of the present invention comprises: a plurality of battery cells; a memory storing the Stage Of Health (SOH) of each of the plurality of battery cells; and a processor diagnosing an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells obtained during the charging process of the plurality of battery cells. The processor is characterized by determining, during the charging of the plurality of battery cells, a target battery cell having a lower voltage rise rate compared to other battery cells based on the SOH stored in the memory, determining a compensation voltage to compensate for the lower voltage rise rate of the target battery cell, determining a diagnosis voltage by compensating the target cell voltage of the target battery cell through the determined compensation voltage, and then diagnosing an internal short circuit of the target battery cell through the determined diagnosis voltage.

[0030]

[0031] According to the present invention, when diagnosing an internal short circuit in a target battery cell having a higher SOH compared to other battery cells during the charging process, the internal short circuit in the target battery cell is diagnosed using a voltage (i.e., a diagnostic voltage) in which the measured cell voltage is compensated by a compensation voltage for a low voltage rise rate compensation, rather than the cell voltage measured for the target battery cell. This prevents misdiagnosis that an internal short circuit has occurred in the target battery cell, as the cell voltage of the target battery cell is formed lower than the cell voltage of other battery cells due to the low voltage rise rate caused by the high SOH.

[0032] However, the effects obtainable through the present invention are not limited to those described above, and other unmentioned technical effects will be clearly understood by those skilled in the art from the description of the invention below.

[0033]

[0034] 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.

[0035] FIG. 1 is an exemplary diagram illustrating a rectangular battery according to one embodiment of the present invention.

[0036] FIG. 2 is a cross-sectional view of a rectangular battery according to one embodiment of the present invention.

[0037] FIG. 3 is a perspective view of a battery module according to one embodiment of the present invention.

[0038] FIGS. 4a and 4b are perspective views of a battery pack according to one embodiment of the present invention.

[0039] FIG. 5 is a block diagram showing a battery management system and a battery pack according to one embodiment of the present invention.

[0040] FIG. 6 is a block diagram showing a battery diagnostic device according to one embodiment of the present invention.

[0041] FIG. 7 is an exemplary diagram showing the cell voltage change of a representative battery cell and the cell voltage change of a target battery cell according to one embodiment of the present invention.

[0042] FIG. 8 is a flowchart showing a battery diagnostic method according to one embodiment of the present invention.

[0043]

[0044] Preferred embodiments of the present invention will be described in detail below 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. Instead, based on the principle that the inventor may appropriately define the concepts of terms to best describe his invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention. Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention; thus, various equivalents and modifications that can replace them may exist at the time of filing this application. Furthermore, as used in this specification, "comprise" or "include" and / or "comprising" or "including" specify the presence of the mentioned features, numbers, steps, actions, parts, elements, and / or groups thereof, and do not exclude the presence or addition of one or more other features, numbers, actions, parts, elements, and / or groups. In addition, when describing embodiments of the present invention, "may" and "may be" may include "one or more embodiments of the present invention."

[0045] Additionally, to aid in understanding the invention, the attached drawings are not drawn to actual scale, and the dimensions of some components may be exaggerated. Furthermore, the same reference numerals may be assigned to identical components in different embodiments.

[0046] The statement that two subjects of comparison are 'identical' means that they are 'substantially identical.' Therefore, substantial identity may include deviations considered low in the industry, for example, deviations within 5%. Additionally, the statement that a parameter is uniform in a given area may mean that it is uniform from an average perspective.

[0047] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0048] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0049] The fact that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0050] Furthermore, where it is stated that one component is "connected," "coupled," or "connected" to another component, it should be understood that while said components may be directly connected or connected to each other, another component may be "interposed" between each component, or that each component may be "connected," "coupled," or "connected" through another component. Additionally, when it is stated that a part is electrically coupled with another part, this includes not only cases where they are directly connected but also cases where they are connected with another component in between.

[0051] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise. That is, "and / or" includes any combination or any combination of the enumerated items. "C to D" means C or more and D or less, unless specifically stated otherwise.

[0052]

[0053] 1. Battery Structure

[0054] Before providing a detailed description of the present embodiment, the structure of the battery subject to diagnosis in this embodiment will be described in general terms. Although a prismatic battery is described below as an example, various types of batteries, such as coin batteries, cylindrical batteries, or pouch batteries, may be employed as the battery subject to diagnosis in this embodiment.

[0055]

[0056] [Primary Battery]

[0057] FIG. 1 is a perspective view illustrating a secondary battery applied to the present embodiment, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1.

[0058] Referring to FIGS. 1 and 2, the secondary battery (C) (secondary battery cell) according to the present embodiment may include at least one electrode assembly (10) wound with an insulator separator (13) interposed between a positive electrode (11) and a negative electrode (12), a case (20) in which the electrode assembly (10) is housed, and a cap assembly (30) coupled to an opening of the case (20).

[0059] The positive electrode (11) and the negative electrode (12) may include a coated portion, which is an area where an active material is applied to a current collector formed of a thin metal foil, and an uncoated portion (11a, 12a), which is an area where an active material is not coated.

[0060] The positive electrode (11) and the negative electrode (12) are wound after interposing an insulating separator (13) between them. However, this embodiment is not limited thereto, and the electrode assembly (10) described above may be structured such that positive and negative electrodes, each consisting of a plurality of sheets, are alternately stacked with a separator between them.

[0061] The case (20) forms the overall exterior of the secondary battery (C) and may be formed of a conductive metal such as aluminum, aluminum alloy, or nickel-plated steel. Additionally, the case (20) may provide a space for accommodating the electrode assembly (10).

[0062] The cap assembly (30) may include a cap plate (31) covering the opening of the case (20), and the case (20) and the cap plate (31) may be made of a conductive material. Here, positive and negative terminals (21, 22) electrically connected to the positive electrode (11) or negative electrode (12) may be installed so as to protrude outward through the cap plate (31).

[0063] Additionally, the outer surface of the upper column of the positive and negative terminals (21, 22) protruding outward from the cap plate (31) can be screwed and secured to the cap plate (31) with a nut.

[0064] However, the present embodiment is not limited thereto, and the positive and negative terminals (21, 22) may be formed with a rivet structure and joined by riveting, or may be joined by welding to the cap plate (31).

[0065] Additionally, the cap plate (31) may be made of a thin plate and may be coupled to the opening of the case (20), and the cap plate (31) may have an electrolyte injection port (32) formed therein where a sealing plug (33) may be installed, and a vent portion (34) with a notch (34a) may be installed.

[0066] The positive and negative terminals (21, 22) can be electrically connected to a current collector comprising first and second current collectors (40, 50) (hereinafter referred to as positive and negative current collectors) that are welded to the positive non-positive portion (11a) or the negative non-positive portion (12a).

[0067] For example, the positive and negative terminals (21, 22) may be joined to the positive and negative current collectors (40, 50) by welding. However, the present embodiment is not limited thereto, and the positive and negative terminals (21, 22) and the positive and negative current collectors (40, 50) may be formed by being joined integrally.

[0068] Additionally, an insulating member may be installed between the electrode assembly (10) and the cap plate (31). Here, the insulating member may include first and second lower insulating members (60, 70), and each of the first and second lower insulating members (60, 70) may be installed between the electrode assembly (10) and the cap plate (31).

[0069] In addition, according to the present embodiment, one end of a separating member that can be installed opposite one side of the electrode assembly (10) may be installed between the insulating member and the positive or negative terminals (21, 22).

[0070] Here, the separating member may include first and second separating members (80, 90).

[0071] Accordingly, one end of the first and second separating members (80, 90), which can be installed opposite to one side of the electrode assembly (10), may be installed between the first and second lower insulating members (60, 70) and the positive and negative terminals (21, 22).

[0072] Ultimately, the positive and negative terminals (21, 22) welded to the positive and negative current collectors (40, 50) can be coupled to one end of the first and second lower insulating members (60, 70) and the first and second separating members (80, 90).

[0073]

[0074] [Battery Module]

[0075] FIG. 3 is a perspective view showing a battery module according to one embodiment of the present invention.

[0076] Referring to FIG. 3, the battery module (M) according to the present embodiment comprises electrode portions (110, 120), a plurality of battery cells (C) arranged in one direction, a connection tab (200) connecting a battery cell (10a) to an adjacent battery cell (10b), and a protection circuit module (300) having one end connected to the connection tab (200). The protection circuit module (300) may be a Battery Management System (BMS). The connection tab (200) includes a body portion that contacts the electrode portions (110, 120) between adjacent battery cells (10a, 10b) and an extension portion that extends from the body portion and is connected to the protection circuit module (300). The connection tab (200) may be a busbar.

[0077] First, the battery cell (C) may consist of a battery case, an electrode assembly housed within the battery case, and an electrolyte. The electrode assembly and the electrolyte react electrochemically to generate energy. On one side of the battery cell (C), an electrode portion (or terminal portion) (110, 120) electrically connected to a connection tab (200) and a vent (130) serving as a passage for discharging gas generated internally may be provided. The electrode portion (110, 120) of the battery cell (C) may be a positive terminal (110) and a negative terminal (120) having different polarities, and the electrode portions (110, 120) of adjacent battery cells (10a, 10b) may be electrically connected in series or in parallel by the connection tab (200) described below. Meanwhile, although a series connection has been described as an example above, the structure is not limited to this structure, and various connection structures may be adopted as needed. In addition, the number and arrangement of battery cells are not limited to the structure shown in FIG. 3 and can be changed as needed.

[0078] A plurality of battery cells (C) may be arranged in one direction such that the wide surfaces of the battery cells (C) face each other, and the arranged plurality of battery cells (C) may be fixed by a housing (61, 62, 63, 64). The housing (61, 62, 63, 64) may include a pair of end plates (61, 62) facing the wide surfaces of the battery cells (C), and a side plate (63) and a bottom plate (64) connecting the pair of end plates (61, 62). The side plate (63) may support the side of the battery cell (C), and the bottom plate (64) may support the bottom surface of the battery cell (C). Additionally, the pair of end plates (61, 62), the side plate (63), and the bottom plate (64) may be connected by a member such as a bolt (65).

[0079] The protection circuit module (300) is equipped with electronic components and protection circuits, and can be electrically connected to a connection tab (200) to be described later. The protection circuit module (300) includes a first protection circuit module (300a) and a second protection circuit module (300b) extending at different locations along the direction in which a plurality of battery cells (C) are arranged. At this time, the first protection circuit module (300a) and the second protection circuit module (300b) are spaced apart at a certain distance but positioned parallel to each other and can be electrically connected to an adjacent connection tab (200). For example, the first protection circuit module (300a) is formed extending to one side of the upper portion of the plurality of battery cells (C) along the direction in which the plurality of battery cells (C) are arranged, and the second protection circuit module (300b) is formed extending to the other side of the upper portion of the plurality of battery cells (C) along the direction in which the plurality of battery cells (C) are arranged, wherein the second protection circuit module (300b) is positioned at a certain distance from the first protection circuit module (300a) with the vent (130) in between, but can be arranged parallel to the first protection circuit module (300a). In this way, the two protection circuit modules are arranged parallel to each other and spaced apart along the direction in which the plurality of battery cells are arranged, thereby minimizing the area of ​​the PCB (Printed Circuit Board) constituting the protection circuit module. By configuring the protection circuit module separately into two protection circuit modules, the unnecessary PCM area is minimized. Additionally, the first protection circuit module (300a) and the second protection circuit module (300b) can be connected to each other by a conductive connecting member (500). At this time, one side of the connecting member (500) is connected to the first protection circuit module (300a), and the other side is connected to the second protection circuit module (300b), thereby enabling an electrical connection between the two protection circuit modules.

[0080] The above connection can be made by any one of the following methods: soldering, resistance welding, laser welding, or projection welding.

[0081] In addition, the connecting member (500) may be, for example, an electric wire. Furthermore, the connecting member (500) may be made of a material having elasticity or flexibility. Through this connecting member (500), the voltage, temperature, and current of a plurality of battery cells (C) can be checked and managed to ensure they are normal. That is, information such as voltage, current, and temperature received by the first protection circuit module from adjacent connection tabs and information such as voltage, current, and temperature received by the second protection circuit module from adjacent connection tabs can be integrated and managed by the protection circuit module through the connecting member.

[0082] In addition, when the battery cell (C) swells, the shock is absorbed by the elasticity or flexibility of the connecting member (500), thereby preventing damage to the first and second protection circuit modules (300a, 300b).

[0083] In addition, the shape and structure of the connecting member (500) are not limited to the shape shown in FIG. 3.

[0084] In this way, by providing the protection circuit module (300) as a first and second protection circuit module (300a, 300b), the area of ​​the PCB constituting the protection circuit module can be minimized, thereby enabling space to be secured inside the battery module. This improves work efficiency by making it easier to perform the fastening work connecting the connection tab (200) and the protection circuit module (300), as well as repairs when an abnormality is detected in the battery module.

[0085]

[0086] [Battery Pack]

[0087] FIGS. 4a and FIGS. 4b are exemplary drawings illustrating a battery pack according to a preferred embodiment of the present invention.

[0088] A battery pack (P) may include a plurality of battery modules (M) and a housing (H) for accommodating the plurality of battery modules (M). For example, the housing (H) may include first and second housings (H1, H2) that are coupled in a direction facing each other with the plurality of battery modules (M) interposed therebetween. The plurality of battery modules (M) may be electrically connected to each other using a busbar (51), and the plurality of battery modules (M) may be electrically connected to each other in a series / parallel or mixed series / parallel manner to obtain the required electrical output.

[0089]

[0090] 2. BMS Circuit Structure

[0091] FIG. 5 is a block diagram showing a battery management system and a battery pack according to one embodiment of the present invention.

[0092] Referring to FIG. 5, the battery management system (BMS) of the present embodiment may include a first processor (PROC1), a second processor (PROC2), a shunt resistor (SR), a charge / discharge switch (SW), a switch driver (SDRV), a regulator (REG), and a fuse device (F), and may form a battery pack (P) together with a battery (BAT). The battery pack (P) of the present embodiment may be used as a power supply for small electronic devices such as mobile phones, laptop computers, or camcorders, or as a power supply for industrial devices such as electric vehicles (EV), hybrid vehicles (HV), or energy storage systems (ESS).

[0093] The battery (BAT) may correspond to a battery module in which a plurality of battery cells (C) are connected in series or in parallel (including a structure in which a plurality of battery modules are connected in series or in parallel). When the battery pack (P) is applied to an electric vehicle, the battery (BAT) may be implemented as a high-voltage battery (e.g., 400V or 800V) that supplies high voltage (e.g., 400V or 800V) (e.g., lithium-ion battery, lithium-polymer battery, nickel-cadmium battery, nickel-hydrogen battery, nickel-zinc battery, etc.). The battery (BAT) may be configured to drive a load (e.g., a driving system of an electric vehicle (e.g., a drive motor and an inverter)) by supplying power to the load, or to be charged by a charging current supplied from an external charging device.

[0094] The first processor (PROC1) may correspond to an Analog Front End (AFE) IC that monitors the status of each battery cell (C) and performs battery cell control operations based on the monitoring results. For example, the first processor (PROC1) may be configured to monitor the voltage, current, temperature, and SOC of the battery cell (C), and, based on the monitoring results, perform control operations such as balancing control, temperature control, and charge / discharge control of the battery cell (C), or perform protection operations such as charge / discharge switch (SW) control to prevent over-discharge or over-charge. The status data of the battery cell (C) obtained by the first processor (PROC1) (i.e., the voltage, current, temperature, and SOC of the battery cell (C)) may be transmitted to the second processor (PROC2) via ISOSPI communication.

[0095] The second processor (PROC2) can generate a control operation command or a protection operation command according to the state data of the battery cell (C) transmitted from the first processor (PROC1) and feed it back to the first processor (PROC1), thereby enabling the first processor (PROC1) to perform the aforementioned control operation and protection operation. The second processor (PROC2) performing this function may correspond to the MCU (Micro Controller Unit) of the BMS. The second processor (PROC2) can communicate with a higher-level controller (CTRLER) (e.g., the ECU of a vehicle equipped with a battery pack (P)) through a communication protocol such as CAN, RTC, or UART.

[0096] The shunt resistor (SR) is connected on a path (corresponding to a charging / discharging path) leading to the positive terminal (P+) of the battery pack (P), the uppermost node (B+) of the plurality of battery cells (C), the lowermost node (B-) of the plurality of battery cells (C), and the negative terminal (P-) of the battery pack (P), and can function as a resistor element for detecting overcurrent flowing through the battery cell (C).

[0097] The charge / discharge switch (SW) may correspond to a MOSFET that interrupts the flow of current in the charge / discharge path described above, and the switch driver (SDRV) may correspond to a gate driver that controls the on / off operation of the charge / discharge switch (SW) under the control of the second processor (PROC2).

[0098] The entity performing the operation of detecting overcurrent through a shunt resistor (SR) and the operation of controlling the on / off of a charge / discharge switch (SW) by controlling a switch driver (SDRV) when an overcurrent is detected may correspond to a first processor (PROC1) or a second processor (PROC2). FIG. 1 shows an example in which the entity performing the above operation corresponds to the second processor (PROC2). In this case, the second processor (PROC2) can detect the state in which an overcurrent flows to the battery cell (C) through a shunt resistor (SR) and control a switch driver (SDRV) to turn off the charge / discharge switch (SW), thereby preventing damage to the battery cell (C) caused by the overcurrent.

[0099] The regulator (REG) can regulate the voltage level at the uppermost node (B+) of the plurality of battery cells (C) to a level corresponding to the operating voltage of the second processor (PROC2), and the operating voltage (VCC) of the second processor (PROC2) can be generated by the regulator (REG). The regulator (REG) can be implemented as a DC / DC converter that converts the voltage at the uppermost node (B+) of the plurality of battery cells (C) into the operating voltage of the second processor (PROC2).

[0100] The fuse device (F) may be configured to interrupt the current path (i.e., the aforementioned charge / discharge path) connected to the battery (BAT) (interruption of the current path may mean interruption of current flow through physical cutting of the current path). A pyrofuse may be employed as the fuse device (F).

[0101]

[0102] 3. Battery Diagnostic Device

[0103] FIG. 6 is a block diagram showing a battery diagnostic device according to an embodiment of the present invention, and FIG. 7 is an example diagram showing the cell voltage change of a representative battery cell and the cell voltage change of a target battery cell according to an embodiment of the present invention. The following embodiments are based on the circuit structure of the battery management system (BMS) of FIG. 5.

[0104] Referring to FIG. 6, the battery diagnostic device of the present embodiment may include a memory (1000) and a processor (2000). The processor (2000) may be configured to include a first processor (PROC1) and a second processor (PROC2) of the aforementioned battery management system (BMS), that is, the battery diagnostic device including the memory (1000) and the processor (2000) may be implemented by being integrated into the battery management system (BMS) or the battery pack (P).

[0105] At least one instruction to be executed by a processor (2000) described later may be stored in the memory (1000). The memory (1000) may be implemented as a volatile storage medium and / or a non-volatile storage medium, for example, as a read-only memory (ROM) and / or random access memory (RAM).

[0106] The memory (1000) may store the State of Health (SOH, %) of each of the multiple battery cells. That is, the SOH of each of the multiple battery cells may be measured in advance and stored in the memory (1000). To explain as an example where a battery management system (BMS) and a battery pack (P) are applied to an electric vehicle, the processor (2000) may measure the SOH of each of the multiple battery cells during a rest period (i.e., a period when the electric vehicle is not operating) under the control of the upper controller (CTRLER) of the electric vehicle and store it in the memory (1000). A known Full Charge-Discharge Test may be applied as a method for measuring SOH, and accordingly, the processor (2000) can measure the SOH of each battery cell by dividing the discharge capacity (i.e., the product of the discharge current and the discharge time) measured during the process of fully discharging the multiple battery cells by the initial nominal capacity of each battery cell (the SOH applied in this embodiment may be SOHc (i.e., SOH related to the battery cell capacity)).

[0107] The processor (2000) acts as a diagnosing entity for internal short circuits of a battery cell (e.g., internal short circuits of a cell caused by lithium salt precipitation occurring on the negative electrode surface of a battery cell), and can be implemented as a Central Processing Unit (CPU) or a System on Chip (SoC). It can control multiple hardware or software components connected to the processor (2000) by running an operating system or application, and can perform various data processing and calculations. The processor (2000) can be configured to execute at least one instruction stored in memory (1000) and store the execution result data in memory (1000).

[0108] In this embodiment, the processor (2000) may be configured to diagnose an internal short circuit of each battery cell during the charging process of a plurality of battery cells, and may diagnose an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells obtained during the charging process of the plurality of battery cells. In this case, the processor (2000) may diagnose an internal short circuit of any one battery cell (i.e., the battery cell subject to internal short circuit diagnosis) during the charging process of the plurality of battery cells by determining whether the cell voltage of any one battery cell (i.e., the battery cell subject to internal short circuit diagnosis) is lower than or equal to a preset threshold value compared to a reference voltage determined based on the cell voltages of each of the plurality of battery cells. The reference voltage may correspond to the mean of the cell voltages of the plurality of battery cells or the median of the cell voltages.

[0109] That is, if the cell voltage of any one battery cell is lower than the threshold value above the average or median value, it can be considered that the cell voltage is lower compared to other battery cells due to an internal short circuit in the battery cell; therefore, in this case, the processor (2000) can determine that an internal short circuit has occurred in the battery cell. The threshold value above may be designed as a specific value according to the specifications of the battery cell and the designer's intention.

[0110] Meanwhile, in the case of a battery pack (P) with multiple battery cells, the usage of each battery cell may have unbalanced characteristics due to the usage environment of the battery pack (P) or the balancing operation of each battery cell, and thus a deviation in SOH between multiple battery cells may occur. As shown in FIG. 7, in the case of a battery cell with a relatively small SOH (i.e., a battery cell with significant degradation due to use), the voltage rise rate (i.e., voltage rise speed) during the charging process is large, and in the case of a battery cell with a relatively large SOH (i.e., a battery cell with minimal degradation due to use), the voltage rise rate during the charging process is small. Based on a specific point in time during the charging process (T1 or T2 in FIG. 7), the cell voltage of the battery cell with a large SOH appears smaller than the cell voltage of the battery cell with a small SOH, and the voltage deviation (DEV1, DEV2) is proportional to the SOH deviation between the two battery cells. Therefore, the higher the SOH of a specific battery cell, the lower its cell voltage is measured during the charging process. This creates the possibility that the specific battery cell may be misdiagnosed as an abnormal battery cell with an internal short circuit even though it is in a normal state (in the above case, if the cell voltage of the specific battery cell is lower than the threshold value relative to the aforementioned reference voltage, the specific battery cell is misdiagnosed as having an internal short circuit even though it is in a normal state). To prevent such misdiagnosis of an internal short circuit, the present embodiment adopts a configuration in which, when diagnosing an internal short circuit during the charging process of a battery (BAT), for a battery cell with a high SOH, the internal short circuit is diagnosed not by the 'measured cell voltage' but by the 'diagnostic voltage' in which the measured cell voltage is compensated by a compensation voltage (described later).

[0111] Specifically, when charging multiple battery cells, the processor (2000) determines a target battery cell having a lower voltage rise rate compared to other battery cells based on the SOH stored in the memory (1000), determines a compensation voltage to compensate for the lower voltage rise rate of the target battery cell, compensates the cell voltage of the target battery cell through the determined compensation voltage to determine a diagnostic voltage, and then diagnoses an internal short circuit of the target battery cell through the determined diagnostic voltage.

[0112] When determining the target battery cells to be subject to cell voltage compensation, the processor (2000) may determine only the battery cells that are likely to be misdiagnosed as having an internal short circuit even in a normal state, due to having a relatively high SOH compared to other battery cells, as target battery cells, rather than determining all battery cells as target battery cells. One or multiple battery cells among a plurality of battery cells may be determined as target battery cells. In an embodiment where a single battery cell is determined as the target battery cell, the processor (2000) may determine the battery cell having the maximum SOH among a plurality of SOHs stored in memory (1000) as the target battery cell. In an embodiment where a plurality of battery cells are determined as target battery cells, the processor (2000) may determine the first to Nth battery cells, each having a first to Nth SOH based on the order of increasing SOH, as target battery cells (N is a natural number greater than or equal to 2) (i.e., the top N battery cells with the largest SOH may be determined as target battery cells).

[0113] When a target battery cell is determined, the processor (2000) can determine a compensation voltage to compensate for the low voltage rise rate of the target battery cell. In this case, the processor (2000) can determine the compensation voltage based on the cell voltage (hereinafter, representative cell voltage) of a representative battery cell having a SOH (hereinafter, representative SOH) corresponding to a statistical representative value among a plurality of SOHs, and the value of a SOH ratio factor based on the ratio of the SOH of the target battery cell (hereinafter, target SOH) to the representative SOH. Here, the SOH ratio factor can be defined as a value obtained by subtracting 1 from the ratio of the target SOH to the representative SOH.

[0114] The compensation voltage can be expressed according to the following mathematical formula 1.

[0115]

[0116] V in mathematical equation 1 comp is the compensation voltage, and V cell_rep is the representative cell voltage, and Factor SOHRatio is the SOH ratio factor, and SOH cell_rep is the representative SOH, and SOH cell_target is the target SOH.

[0117] The statistical representative value mentioned above may be a median. Accordingly, the processor (2000) may determine a representative battery cell having a representative SOH corresponding to the median among a plurality of SOHs, and may determine a compensation voltage based on the product of the representative cell voltage of the representative battery cell and the SOH ratio factor based on the ratio of the target SOH to the representative SOH. In another embodiment, the statistical representative value may be a mean. Accordingly, the processor (2000) may determine a representative battery cell having a representative SOH corresponding to the mean among a plurality of SOHs (a battery cell having the SOH closest to the representative SOH may be determined as the representative battery cell), and may determine a compensation voltage based on the product of the representative cell voltage of the representative battery cell and the SOH ratio factor based on the ratio of the target SOH to the representative SOH.

[0118] Meanwhile, referring to FIG. 7, since the voltage rise rate of a battery cell with a small SOH is large during the charging process and the voltage rise rate of a battery cell with a large SOH is small during the charging process, the difference between the cell voltage of the battery cell with a small SOH and the cell voltage of the battery cell with a large SOH increases as charging progresses. That is, even if the battery cell with a large SOH is diagnosed as normal because the voltage deviation (DEV1) is small at time T1 in FIG. 7, the voltage deviation (DEV2) at time T2 after T1 is formed as a value larger than the voltage deviation (DEV1) at time T1, so there is a possibility of misdiagnosing that an internal short circuit has occurred in the battery cell with a large SOH. Therefore, it is necessary to actively compensate for the voltage deviation with other battery cells that increases as charging progresses due to the low voltage rise rate of the battery cell with a large SOH, depending on the time of charging, and for this purpose, a deviation compensation factor may be introduced in this embodiment.

[0119] Specifically, the processor (2000) may determine the compensation voltage by further considering a deviation compensation factor along with the aforementioned representative cell voltage and SOH ratio factors, and specifically, may determine the compensation voltage based on the product of the representative cell voltage, the SOH ratio factor, and the deviation compensation factor. Here, the deviation compensation factor may be defined as a factor that actively compensates for the deviation between the representative cell voltage and the target cell voltage, which increases as charging proceeds due to the low voltage rise rate of the target battery cell, according to the point in time when the target cell voltage is compensated (or a specific point in time during the charging process).

[0120] In order to compensate for the deviation between the representative cell voltage and the target cell voltage that increases as charging progresses, it is necessary to adopt a parameter whose value increases as charging progresses as a deviation compensation factor. To this end, the State of Charge (SOC, %) of the target battery cell at the point when the target cell voltage is compensated (hereinafter, target SOC) can be adopted as a deviation compensation factor. That is, since the target SOC also increases as charging progresses, the deviation between the representative cell voltage and the target cell voltage that increases as charging progresses can be compensated through the target SOC.

[0121] In this case, the compensation voltage can be expressed according to the following mathematical formula 2.

[0122]

[0123] Factor in mathematical equation 2 comp_dev is the deviation compensation factor, and SOC cell_target is the target SOC.

[0124] When the compensation voltage is determined, the processor (2000) can determine the diagnostic voltage by compensating the target cell voltage of the target battery cell through the compensation voltage. In this case, the processor (2000) can determine the diagnostic voltage as the sum of the target cell voltage and the compensation voltage.

[0125] When applying the compensation voltage according to Equation 2, the diagnostic voltage can be expressed according to Equation 3 below.

[0126]

[0127] V in mathematical equation 3 diag is the diagnostic voltage, and V cell_target is the target cell voltage.

[0128] When the diagnostic voltage is determined, the processor (2000) diagnoses an internal short circuit in each battery cell based on the cell voltage of each of the plurality of battery cells, and for the target battery cell, it can diagnose the internal short circuit using the diagnostic voltage determined according to Equation 3 above. As the diagnosis of the internal short circuit of the target battery cell is performed based on the diagnostic voltage in which a compensation voltage is added to the target cell voltage, the possibility of a misdiagnosis of an internal short circuit can be eliminated. If an internal short circuit actually occurs in the target battery cell, the target cell voltage (i.e., V in Equation 3) cell_target Since the ) itself decreases, the internal short circuit can be diagnosed normally.

[0129] Table 1 below shows an example where the target cell voltage is compensated through the compensation voltage to generate the diagnostic voltage.

[0130] Target SOH Target Cell Voltage Target SOC Representative SOH Representative Cell Voltage 90% 3.6V 60% 85% 3.8V Diagnostic Voltage 3.6 + [3.8V x (0.90 / 0.85 - 1) x 0.6 = 3.73 [V]

[0131] According to Table 1, the diagnosis of an internal short circuit of the target battery cell is performed using the diagnostic voltage of 3.73V rather than the target cell voltage (i.e., the actual cell voltage of the target battery cell) of 3.6V, thereby preventing a false diagnosis of an internal short circuit caused by the low cell voltage of the target battery cell.

[0132]

[0133] 4. Battery Diagnostic Methods

[0134] FIG. 8 is a flowchart illustrating a battery diagnostic method according to an embodiment of the present invention. The battery diagnostic method of the present embodiment is described with reference to FIG. 8; specific descriptions of components that overlap with the foregoing are omitted, and the description focuses on the chronological configuration.

[0135] First, the processor (2000) initiates charging of a plurality of battery cells (S100). In step S100, the processor (2000) recognizes that an external charging device is connected to the positive terminal (P+) and negative terminal (P-) of the battery pack (P) and can initiate charging of the plurality of battery cells by closing the charge / discharge switch (SW) through the switch driver (SDRV).

[0136] Next, the processor (2000) determines a target battery cell having a lower voltage rise rate compared to other battery cells based on the SOH of each of the plurality of battery cells (S200). In step S200, the processor (2000) may determine a target battery cell that has the maximum SOH among the plurality of SOHs, or a first to Nth battery cell that has the first to Nth SOHs respectively based on the order of the largest SOHs.

[0137] Next, the processor (2000) determines a compensation voltage to compensate for the low voltage rise rate of the target battery cell (S300).

[0138] In step S300, the processor (2000) can determine a compensation voltage based on the product of the representative cell voltage of a representative battery cell having a representative SOH corresponding to a statistical representative value among a plurality of SOHs, and the SOH ratio factor based on the ratio of the target SOH of the target battery cell to the representative SOH of the representative battery cell. Here, the statistical representative value may be a median or an average value, and the SOH ratio factor may be a value obtained by subtracting 1 from the ratio of the target SOH to the representative SOH.

[0139] In step S300, the processor (2000) may determine a compensation voltage based on the product of a representative cell voltage, an SOH ratio factor, and a deviation compensation factor. Here, the deviation compensation factor may be a factor for actively compensating for the deviation between the representative cell voltage and the target cell voltage that increases as charging proceeds due to the low voltage rise rate of the target battery cell, depending on the time at which the target cell voltage is compensated. For example, the deviation compensation factor may be the SOC of the target battery cell at the time at which the target cell voltage is compensated.

[0140] Subsequently, the processor (2000) determines the diagnostic voltage by compensating the target cell voltage of the target battery cell through the compensation voltage determined in step S300 (S400). In step S400, the processor (2000) can determine the diagnostic voltage as the sum of the target cell voltage and the compensation voltage.

[0141] Next, the processor (2000) diagnoses an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells (S500). In step S500, the processor (2000) can diagnose an internal short circuit of one of the battery cells by determining whether the cell voltage of one of the battery cells is lower than a preset threshold value relative to a reference voltage determined based on the cell voltages of each of the plurality of battery cells. At this time, the processor (2000) can diagnose an internal short circuit of the target battery cell using the diagnosis voltage determined in step S400 for the target battery cell.

[0142]

[0143] As such, according to the present invention, when diagnosing an internal short circuit in a target battery cell having a higher SOH compared to other battery cells during the charging process, the internal short circuit in the target battery cell is diagnosed through a voltage (i.e., a diagnostic voltage) in which the measured cell voltage is compensated by a compensation voltage for a low voltage rise rate compensation, rather than the cell voltage measured for the target battery cell. This prevents misdiagnosis that an internal short circuit has occurred in the target battery cell, as the cell voltage of the target battery cell is formed lower than the cell voltage of other battery cells due to the low voltage rise rate caused by the high SOH.

[0144] The implementations described herein may be implemented, for example, as methods or processes, devices, software programs, data streams, or signals. Even if discussed only in the context of a single form of implementation (e.g., discussed only as a method), the implementation of the discussed features may also be implemented in other forms (e.g., devices or programs). Devices may be implemented in appropriate hardware, software, and firmware, etc. Methods may be implemented in devices such as processors, which generally refer to processing devices including, for example, computers, microprocessors, integrated circuits, or programmable logic devices. Processors also include communication devices such as computers, cell phones, portable / personal digital assistants ("PDAs"), and other devices that facilitate the communication of information between end-users.

[0145] 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.

Claims

1. A memory storing the State of Health (SOH) of each of multiple battery cells; and A processor that diagnoses an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells obtained during the charging process of the plurality of battery cells; A battery diagnostic device characterized by the processor determining, based on the SOH stored in the memory, a target battery cell having a lower voltage rise rate compared to other battery cells when charging the plurality of battery cells, determining a compensation voltage to compensate for the lower voltage rise rate of the target battery cell, determining a diagnostic voltage by compensating the target cell voltage of the target battery cell through the determined compensation voltage, and then diagnosing an internal short circuit of the target battery cell through the determined diagnostic voltage.

2. In Paragraph 1, A battery diagnostic device characterized by the above processor diagnosing an internal short circuit of any one battery cell by determining whether the cell voltage of any one battery cell is lower than a preset threshold value relative to a reference voltage determined based on the cell voltage of each of the plurality of battery cells.

3. In Paragraph 1, A battery diagnostic device (N is a natural number greater than or equal to 2) characterized in that the processor determines as the target battery cell one battery cell having the maximum SOH among the plurality of SOHs, or first to N battery cells each having a first to N SOH based on the order of largest SOH.

4. In Paragraph 1, A battery diagnostic device characterized by the processor determining the compensation voltage based on the product value of a representative cell voltage of a representative battery cell having a representative SOH corresponding to a statistical representative value among the plurality of SOHs, and a SOH ratio factor based on the ratio of the target SOH of the target battery cell to the representative SOH of the representative battery cell.

5. In Paragraph 4, A battery diagnostic device characterized in that the above statistical representative value is the median or mean.

6. In Paragraph 4, A battery diagnostic device characterized in that the above SOH ratio factor is a value obtained by subtracting 1 from the ratio of the above target SOH to the above representative SOH.

7. In Paragraph 4, The processor determines the compensation voltage based on the product of the representative cell voltage, the SOH ratio factor, and the deviation compensation factor, A battery diagnostic device characterized in that the deviation compensation factor is a factor for actively compensating for the deviation between the representative cell voltage and the target cell voltage, which increases as charging proceeds due to the low voltage rise rate of the target battery cell, according to the time when the target cell voltage is compensated.

8. In Paragraph 7, A battery diagnostic device characterized in that the above deviation compensation factor is the State of Charge (SOC) of the target battery cell at the time when the target cell voltage is compensated.

9. In Paragraph 1, A battery diagnostic device characterized by the above processor determining the diagnostic voltage as the sum of the target cell voltage and the compensation voltage.

10. A step in which the processor initiates charging of a plurality of battery cells; The above processor determines a target battery cell having a lower voltage rise rate compared to other battery cells based on the SOH of each of the plurality of battery cells; The above processor determines a compensation voltage to compensate for the low voltage rise rate of the target battery cell; The above processor determines a diagnostic voltage by compensating the target cell voltage of the target battery cell through the determined compensation voltage; and The above processor diagnoses an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells, and for the target battery cell, diagnoses an internal short circuit of the target battery cell using the determined diagnosis voltage; A battery diagnostic method characterized by including 11. In Paragraph 10, In the step of diagnosing the internal short circuit mentioned above, the processor, A battery diagnosis method characterized by diagnosing an internal short circuit of any one battery cell by determining whether the cell voltage of any one battery cell is lower than a preset threshold value relative to a reference voltage determined based on the cell voltage of each of the plurality of battery cells.

12. In Paragraph 10, In the step of determining the above target battery cell, the processor, A battery diagnostic method characterized by determining, as the target battery cell, one battery cell having the maximum SOH among the plurality of SOHs, or the first to Nth battery cells each having the first to Nth SOHs based on the order of increasing SOH (N is a natural number greater than or equal to 2).

13. In Paragraph 10, In the step of determining the compensation voltage, the processor, A battery diagnostic method characterized by determining the compensation voltage based on the product of a representative cell voltage of a representative battery cell having a representative SOH corresponding to a statistical representative value among the plurality of SOHs, and a SOH ratio factor based on the ratio of the target SOH of the target battery cell to the representative SOH of the representative battery cell.

14. In Paragraph 13, A battery diagnostic method characterized in that the above statistical representative value is the median or mean.

15. In Paragraph 13, A battery diagnostic method characterized in that the above SOH ratio factor is a value obtained by subtracting 1 from the ratio of the above target SOH to the above representative SOH.

16. In Paragraph 13, In the step of determining the compensation voltage, the processor, The compensation voltage is determined based on the product of the above representative cell voltage, the above SOH ratio factor, and the deviation compensation factor, wherein A battery diagnostic method characterized in that the deviation compensation factor is a factor for actively compensating for the deviation between the representative cell voltage and the target cell voltage, which increases as charging proceeds due to the low voltage rise rate of the target battery cell, according to the time when the target cell voltage is compensated.

17. In Paragraph 16, A battery diagnostic method characterized in that the deviation compensation factor is the State of Charge (SOC) of the target battery cell at the time when the target cell voltage is compensated.

18. In Paragraph 10, In the step of determining the above diagnostic voltage, the processor, A battery diagnosis method characterized by determining the diagnosis voltage as the sum of the target cell voltage and the compensation voltage.

19. Multiple battery cells; A memory storing the State of Health (SOH) of each of the plurality of battery cells; and A processor that diagnoses an internal short circuit of each battery cell based on the cell voltage of each of the plurality of battery cells obtained during the charging process of the plurality of battery cells; A battery pack characterized by the processor determining, based on the SOH stored in the memory, a target battery cell having a lower voltage rise rate compared to other battery cells when charging the plurality of battery cells, determining a compensation voltage to compensate for the lower voltage rise rate of the target battery cell, determining a diagnostic voltage by compensating the target cell voltage of the target battery cell through the determined compensation voltage, and then diagnosing an internal short circuit of the target battery cell through the determined diagnostic voltage.

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