Battery management device, battery pack, and battery management method

Abstract

A battery management device according to one embodiment of the present disclosure includes: an EIS unit configured to output an alternating current to a battery at a plurality of time points, and generate, at each of the plurality of time points, an EIS curve showing an electrical resistance of the battery as a correspondence between a real part and an imaginary part; and a control unit that obtains a plurality of EIS curves with respect to the battery generated by the EIS unit, determines a plurality of arcs at each of the plurality of EIS curves, calculates an arc resistance value with respect to each of the determined plurality of arcs, calculates a resistance change rate with respect to arc resistance values between corresponding arcs of the plurality of arcs, and determines each of the plurality of arcs as a negative electrode arc initiation or a positive electrode arc initiation based on the calculated plurality of resistance change rates and a preset standard change rate.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application 10-2020-0184946, filed in Korea on December 28, 2020, the disclosure of which is incorporated herein by reference.

[0002] This disclosure relates to a battery management device and a battery management method, and more specifically to a battery management device and a battery management method capable of distinguishing multiple arcs included in the EIS (electrochemical impedance spectroscopy) curve of a battery into negative electrode arcing and positive electrode arcing. Background Technology

[0003] Recently, demand for portable electronic products such as laptops, cameras, and mobile phones has increased dramatically, and electric vehicles, energy storage batteries, robots, and satellites have also seen significant development. Therefore, high-performance batteries that allow for repeated charging and discharging are being actively researched.

[0004] Currently available commercial batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Among them, lithium batteries have attracted much attention because they have almost no memory effect compared to nickel-based batteries, and also have a very low self-discharge rate and high energy density.

[0005] Traditionally, the state of a battery is estimated using electrochemical impedance spectroscopy (EIS). However, as the battery degrades, the Nyquist plot represented by EIS may include multiple arcs. Since these multiple arcs are influenced to some extent by both the negative and positive electrodes, it is difficult in the prior art to distinguish between negative electrode arcing and positive electrode arcing. Summary of the Invention

[0006] Technical issues

[0007] This disclosure aims to address the problems of the prior art, and therefore aims to provide a battery management device and battery management method that can distinguish between arcs related to the increase in negative electrode resistance and arcs related to the increase in positive electrode resistance in the EIS curve.

[0008] These and other objects and advantages of this disclosure will become apparent from the following detailed description and will become more apparent from exemplary embodiments thereof. Furthermore, it will be readily understood that the objects and advantages of this disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

[0009] Technical solution

[0010] A battery management device according to one aspect of this disclosure may include: an EIS unit configured to output AC current to a battery at multiple time points and generate multiple EIS curves representing the resistance of the battery as a correspondence between the real and imaginary parts at each of the multiple time points; and a control unit configured to obtain the multiple EIS curves of the battery generated by the EIS unit, determine multiple arcs in each of the multiple EIS curves, calculate the arc resistance value of each of the determined multiple arcs, calculate the resistance change rate of the arc resistance values ​​between corresponding arcs in the multiple arcs, and determine each of the multiple arcs as either a negative arc or a positive arc based on the calculated multiple resistance change rates and a preset standard change rate.

[0011] The control unit can be configured to set the resistance change rate that is equal to or less than the standard change rate among the plurality of resistance change rates as the first resistance change rate, and set the remaining resistance change rates as the second resistance change rate.

[0012] The control unit can be configured to identify multiple arcs in the plurality of EIS curves corresponding to the first resistance change rate as the negative electrode arc initiation, and to identify multiple arcs in the plurality of EIS curves corresponding to the second resistance change rate as the positive electrode arc initiation.

[0013] The control unit can be configured to obtain at least one of a battery curve representing the correspondence between the SOC and voltage of the battery and a differential curve representing the correspondence between the SOC and the differential voltage relative to the SOC, and to set a standard SOC range based on the battery curve and the at least one of the differential curves.

[0014] The control unit can be configured to select a first SOC and a second SOC within a set standard SOC range.

[0015] The EIS unit can be configured to generate an EIS curve for a battery in a first state corresponding to the first SOC, and to generate an EIS curve for a battery in a second state corresponding to the second SOC.

[0016] The control unit can be configured to select a first SOC and a second SOC within the set standard SOC range, determine a first voltage corresponding to the first SOC, and determine a second voltage corresponding to the second SOC.

[0017] The EIS unit can be configured to generate an EIS curve for a battery in a first state corresponding to the first SOC, and to generate an EIS curve for a battery in a second state corresponding to the second SOC.

[0018] The control unit can be configured to select the negative electrode flat range of the battery in the battery curve and set the selected negative electrode flat range as the standard SOC range.

[0019] The control unit can be configured to determine a target peak in the differential curve and set the SOC interval that is equal to or greater than the SOC corresponding to the determined target peak as the standard SOC interval.

[0020] The control unit can be configured to determine the peak value with the maximum differential voltage in the SOC range of 40% to 100% of the differential curve as the target peak value.

[0021] The EIS unit can be configured to generate the plurality of EIS curves within one charge-discharge cycle of the battery.

[0022] A battery pack according to another aspect of this disclosure may include a battery management device according to another aspect of this disclosure.

[0023] A battery management method according to another aspect of this disclosure may include: an EIS curve generation step, which outputs AC current to the battery at multiple time points and generates multiple EIS curves representing the resistance of the battery as a correspondence between the real and imaginary parts at each of the multiple time points; an arc resistance value calculation step, which determines multiple arcs in each of the multiple EIS curves generated in the EIS curve generation step and calculates the arc resistance value of each of the determined multiple arcs; a resistance change rate calculation step, which calculates the resistance change rate between corresponding arcs in the multiple arcs; and an arc analysis step, which determines each of the multiple arcs as either a negative electrode arc or a positive electrode arc based on the calculated multiple resistance change rates and a preset standard change rate.

[0024] Beneficial effects

[0025] According to one aspect of this disclosure, an advantage is that the multiple arcs included in the EIS curve can be specifically distinguished and diagnosed as negative electrode arcing and positive electrode arcing. Therefore, in the process of diagnosing the battery state based on the EIS curve, the negative electrode degradation state of the battery can be diagnosed more specifically based on negative electrode arcing, and the positive electrode degradation state of the battery can be diagnosed more specifically based on positive electrode arcing.

[0026] The effects of this disclosure are not limited to those described above; other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. Attached Figure Description

[0027] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide a further understanding of the technical features of the present disclosure; therefore, the present disclosure is not to be construed as being limited to the illustrations.

[0028] Figure 1 This is a schematic diagram illustrating a battery management device according to one embodiment of the present disclosure.

[0029] Figure 2 This is a diagram schematically illustrating a first EIS curve according to one embodiment of the present disclosure.

[0030] Figure 3 This is a diagram schematically illustrating a second EIS curve according to one embodiment of the present disclosure.

[0031] Figure 4 This is a schematic diagram illustrating a battery curve according to one embodiment of the present disclosure.

[0032] Figure 5 This is a schematic diagram illustrating a differential curve according to one embodiment of the present disclosure.

[0033] Figure 6 This is a diagram schematically illustrating an exemplary configuration of a battery pack according to another embodiment of the present disclosure.

[0034] Figure 7 This is a schematic diagram illustrating a battery management method according to another embodiment of the present disclosure. Detailed Implementation

[0035] It should be understood that the terms used in the specification and appended claims should not be construed as limited to their general and dictionary meanings, but rather are interpreted according to their meanings and concepts corresponding to the technical aspects of this disclosure, based on the principle that inventors are allowed to make appropriate definitions of the terms to obtain the best interpretation.

[0036] Therefore, the description presented herein is merely a preferred embodiment for illustrative purposes and is not intended to limit the scope of the disclosure. It should be understood that other equivalents and modifications may be made to this disclosure without departing from its scope.

[0037] Furthermore, in the description of this disclosure, detailed descriptions of relevant known elements or functions are omitted where such detailed descriptions would obscure the key subject matter of this disclosure.

[0038] Ordinal terms such as “first” and “second” can be used to distinguish one element from another among various elements, but are not intended to limit elements by means of terms.

[0039] Throughout this specification, when a section is referred to as “containing” or “including” any element, it means that the section may additionally include other elements, without excluding other elements, unless otherwise specifically stated.

[0040] Furthermore, throughout the specification, when one part is referred to as being "connected" to another part, it is not limited to the case where they are "directly connected," but also includes the case where they are "indirectly connected" by inserting another element between them.

[0041] The preferred embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.

[0042] Figure 1 This is a schematic diagram illustrating a battery management device 100 according to one embodiment of the present disclosure.

[0043] refer to Figure 1 According to one embodiment of the present disclosure, the battery management device 100 may include an EIS unit 110 and a control unit 120.

[0044] Here, a battery can refer to a physically separable, individual cell comprising a negative terminal and a positive terminal. For example, a pouch-type lithium polymer cell can be considered a battery. Furthermore, a battery can refer to a battery module in which multiple battery cells are connected in series and / or parallel. However, for ease of explanation, in the following text, a battery will be described as referring to a single battery cell.

[0045] EIS unit 110 can measure the resistance of a battery using electrochemical impedance spectroscopy (EIS).

[0046] Specifically, the EIS unit 110 can be configured to output AC current to the battery at multiple points in time.

[0047] The multiple time points at which the EIS unit 110 outputs AC current to the battery can refer to different time points within a charge-discharge cycle of the battery.

[0048] For example, at the first time point of the 100th charge-discharge cycle of the battery, the EIS unit 110 can output AC current to the battery. Additionally, at the second time point of the 100th charge-discharge cycle of the battery, the EIS unit 110 can output AC current to the battery. Here, the first time point and the second time point can be different time points, and the first time point can be an earlier time point than the second time point.

[0049] EIS unit 110 can be configured to generate an EIS curve representing the battery resistance as a correspondence between the real and imaginary parts at each time point.

[0050] Specifically, when the real part is set to X and the imaginary part is set to Y, the EIS curve can be represented as an XY plot and / or an XY table. The unit of the real part can be represented as Zre [ohms, Ω], and the unit of the imaginary part can be represented as -Zim [ohms, Ω]. For example, the EIS curve can be represented as a Nyquist plot.

[0051] Figure 2 This is a diagram schematically illustrating a first EIS curve according to one embodiment of the present disclosure. Figure 3 This is a diagram schematically illustrating a second EIS curve according to one embodiment of the present disclosure.

[0052] Specifically, the first EIS curve is generated after the EIS unit 110 outputs AC current to the battery at the first time point. Furthermore, the second EIS curve is generated after the EIS unit outputs AC current to the battery at the second time point.

[0053] The control unit 120 can be configured to obtain multiple EIS curves of the battery generated by the EIS unit 110.

[0054] For example, the control unit 120 can be connected to communicate with the EIS unit 110. The EIS unit 110 can output multiple generated EIS curves, and the control unit 120 can receive multiple EIS curves output from the EIS unit 110.

[0055] The control unit 120 can be configured to determine multiple arcs for each of a plurality of EIS curves. Specifically, the control unit 120 can be configured to determine the number of multiple arcs for each of the plurality of EIS curves.

[0056] exist Figure 2 In one implementation, the control unit 120 can determine that the first EIS curve includes two arcs based on the rate of change of the imaginary part (-Zim) with respect to the real part (Zre).

[0057] In addition, Figure 3 In one implementation, the control unit 120 can determine that the second EIS curve includes two arcs based on the rate of change of the imaginary part (-Zim) with respect to the real part (Zre).

[0058] For example, in the first and second EIS curves, the increasing / decreasing trend of the rate of change of the imaginary part (-Zim) relative to the real part (Zre) can vary based on R1. Specifically, in the interval before R1, the rate of change of the imaginary part (-Zim) with respect to the real part (Zre) tends to decrease, but starting from R1, the rate of change of the imaginary part (-Zim) with respect to the real part (Zre) can increase. Therefore, the control unit 120 can determine, based on R1, that each of the first and second EIS curves includes two arcs.

[0059] As another embodiment, the control unit 120 can determine, based on the change in curvature of each of the first and second EIS curves, that each of the first and second EIS curves includes two arcs. For example, in Figure 2 and Figure 3 In this implementation, based on point R1, the curvature in the interval before R1 and the curvature in the interval after R1 may be significantly different from each other. Therefore, the control unit 120 can determine, based on R1, that each of the first and second EIS curves includes two arcs.

[0060] The control unit 120 can be configured to calculate the rate of change of resistance between corresponding arc resistance values ​​among multiple arcs.

[0061] First, the control unit 120 can determine the equivalent circuit model (ECM) corresponding to each of the multiple EIS curves.

[0062] For example, in Figure 2 and Figure 3 In the implementation of the method, since the control unit 120 determines that each of the first EIS curve and the second EIS curve includes two arcs, the equivalent circuit model including two RC parallel circuits can be determined as the equivalent circuit model corresponding to the first EIS curve and the second EIS curve.

[0063] In addition, the control unit 120 can calculate the first arc resistance value of the first arc and the second arc resistance value of the second arc by applying curve fitting algorithms to the EIS curve and the equivalent circuit model respectively.

[0064] For example, in Figure 2 In the first EIS curve, the resistance of the first arc can be calculated as 3 mΩ, and the resistance of the second arc can be calculated as 21 mΩ. Furthermore, in Figure 3 In the second EIS curve, the resistance value of the first arc can be calculated as 4mΩ, and the resistance value of the second arc can be calculated as 122mΩ.

[0065] The control unit 120 can calculate the rate of change of resistance of the arc resistance value between the first arcs and the rate of change of resistance of the arc resistance value between the second arcs.

[0066] For example, the control unit 120 can calculate the resistance change rate of the first arc by calculating the ratio of the resistance value of the first arc of the second EIS curve to the resistance value of the first arc of the first EIS curve. Specifically, the control unit 120 can calculate the resistance change rate of the first arc as 1.3 by calculating the formula "4mΩ ÷ 3mΩ".

[0067] Furthermore, the control unit 120 can calculate the resistance change rate of the second arc by calculating the ratio of the second arc resistance value of the second EIS curve to the second arc resistance value of the first EIS curve. Specifically, the control unit 120 can calculate the resistance change rate of the second arc to be 5.9 by calculating the formula "122mΩ ÷ 21mΩ".

[0068] Furthermore, the control unit 120 can be configured to determine each of the multiple arcs as either negative or positive arc initiation based on a calculated multiple resistance change rate and a preset standard change rate.

[0069] Specifically, the control unit 120 can be configured to set the resistance change rate that is equal to or less than the standard change rate among a plurality of resistance change rates as the first resistance change rate, and set the remaining resistance change rates as the second resistance change rate.

[0070] Furthermore, the control unit 120 can be configured to identify multiple arcs in multiple EIS curves corresponding to the first rate of change of resistance as negative arcs, and to identify multiple arcs in multiple EIS curves corresponding to the second rate of change of resistance as positive arcs.

[0071] Here, arcing at the negative terminal is likely more affected by the increased resistance caused by negative terminal degradation than by positive terminal degradation. Conversely, arcing at the positive terminal is likely more affected by the increased resistance caused by positive terminal degradation than by negative terminal degradation.

[0072] As in the previous implementation, it is assumed that the resistance change rate of the first arc is calculated to be 1.3, and the resistance change rate of the second arc is calculated to be 5.9. Furthermore, it is assumed that the standard change rate is preset to 2. The control unit 120 can set the resistance change rate (1.3) of the first arc, which is less than the standard change rate (2), as the first resistance change rate, and set the resistance change rate (5.9) of the second arc as the second resistance change rate. Furthermore, the control unit 120 can determine the first arc of the first EIS curve and the first arc of the second EIS curve corresponding to the first resistance change rate (1.3) as the negative arc initiation. Furthermore, the control unit 120 can determine the second arc of the first EIS curve and the second arc of the second EIS curve corresponding to the second resistance change rate (5.9) as the positive arc initiation.

[0073] The battery management device 100 according to one embodiment of the present disclosure does not simply analyze arcs based on the size of the arc (e.g., arc resistance value) or the order in which the arcs appear in the EIS curve, but can specifically analyze arcs based on the resistance change rate between corresponding arcs in multiple EIS curves.

[0074] That is, since the battery management device 100 does not simply distinguish between negative and positive arcing based on the form of the EIS curve, it can specifically distinguish and diagnose multiple arcs included in the EIS curve as negative or positive arcing.

[0075] Therefore, in the process of diagnosing battery status based on EIS curves, the negative electrode degradation state of the battery can be diagnosed more specifically based on the arcing of the negative electrode, and the positive electrode degradation state can be diagnosed more specifically based on the arcing of the positive electrode.

[0076] Meanwhile, the control unit 120 disposed in the battery management device 100 may optionally include processors known in the art, as well as application-specific integrated circuits (ASICs), other chipsets, logic circuits, registers, communication modems, data processing devices, etc., to execute the various control logics disclosed herein. Furthermore, when the control logic is implemented in software, the control unit 120 can be implemented as a set of program modules. In this case, the program modules can be stored in memory and executed by the control unit 120. The memory can be located internally or externally to the control unit 120 and can be connected to the control unit 120 by known means.

[0077] Furthermore, the battery management device 100 may further include a storage unit 130. The storage unit 130 may store data required for the operation and function of each component of the battery management device 100, data generated during the execution of operations or functions, etc. The type of storage unit 130 is not particularly limited, as long as it is a known information storage means capable of recording, erasing, updating, and retrieving data. As an embodiment, the information storage means may include RAM, flash memory, ROM, EEPROM, registers, etc. In addition, the storage unit 130 may store program code that defines processes executable by the control unit 120.

[0078] For example, multiple EIS curves generated by EIS unit 110 can be stored in storage unit 130. Furthermore, control unit 120 can access storage unit 130 to obtain multiple stored EIS curves.

[0079] The following text will describe in detail the multiple time points at which the EIS curves are generated by EIS unit 110.

[0080] The control unit 120 can be configured to obtain at least one of a battery curve representing the correspondence between the SOC and the battery voltage, and a differential curve representing the correspondence between the SOC and the differential voltage (dV / dSOC) for the SOC.

[0081] The control unit 120 can receive at least one of the battery curve and the differential curve from an external source. Alternatively, at least one of the battery curve and the differential curve can be stored in a storage unit 130, and the control unit 120 can access the storage unit 130 to obtain at least one of the battery curve and the differential curve.

[0082] The control unit 120 can be configured to set a standard SOC range based on at least one of a battery curve and a differential curve. Here, SOC represents the state of charge (SOC) of the battery and can be expressed as "0 to 1" or "0% to 100%". Specific implementation methods for setting the standard SOC range by the control unit 120 will be referenced later. Figure 4 and Figure 5 Describe it.

[0083] For example, the control unit 120 can be configured to select a first SOC and a second SOC within a set standard SOC range. The EIS unit 110 can be configured to generate an EIS curve for the battery corresponding to a first state of the first SOC and an EIS curve for the battery corresponding to a second state of the second SOC.

[0084] That is, when the control unit 120 selects the first SOC and the second SOC, the EIS unit 110 can generate the first EIS curve when the battery is at the first SOC in a charge-discharge cycle, and generate the second EIS curve when the battery's SOC is the second SOC.

[0085] Preferably, the EIS unit 110 can first generate a first EIS curve of the battery, and then generate a second EIS curve. That is, the first time point for generating the first EIS curve can be earlier than the second time point for generating the second EIS curve.

[0086] As another embodiment, the control unit 120 can be configured to select a first SOC and a second SOC within a set standard SOC range, determine a first voltage corresponding to the first SOC, and determine a second voltage corresponding to the second SOC. Furthermore, the EIS unit 110 can be configured to generate an EIS curve for the battery corresponding to a first state of the first voltage, and to generate an EIS curve for the battery corresponding to a second state of the second voltage.

[0087] For example, the first voltage determined by the control unit 120 can be 3.9V, and the second voltage can be 4.2V. Figure 2 In this implementation, when the battery voltage is 3.9V, the EIS unit 110 can generate the battery's first EIS curve. Figure 4In this implementation, when the battery voltage is 4.2V, the EIS unit 110 can generate a second EIS curve for the battery. Similar to the implementation of generating an EIS curve based on SOC, the EIS unit 110 can first generate a first EIS curve when the battery voltage is a first voltage, and then generate a second EIS curve when the battery voltage is a second voltage. That is, the first time point for generating the first EIS curve can be earlier than the second time point for generating the second EIS curve.

[0088] Furthermore, preferably, to prevent the rate of change of resistance calculated by the control unit 120 from being affected by the battery temperature, the battery temperature can be the same when generating the EIS curve. For example, when the battery voltage is 3.9V and the battery temperature is 25°C, the EIS unit 110 can generate a first EIS curve. Additionally, when the battery voltage is 4.2V and the battery temperature is 25°C, the EIS unit 110 can generate a second EIS curve.

[0089] According to one embodiment of this disclosure, a battery management device can generate multiple EIS curves of a battery under identical conditions except for SOC and voltage. That is, the generated multiple EIS curves may be affected only by the battery's SOC and voltage, and may be unaffected by, or minimally affected by, the degree of battery degradation based on charge / discharge cycles and battery temperature. Therefore, the advantage of this battery management device is that, taking into account the battery's current state, it can more accurately distinguish between negative and positive electrode arcing in the generated multiple EIS curves.

[0090] The following describes a specific implementation of the control unit 120 setting the standard SOC range.

[0091] Here, the standard SOC range is such that the first SOC and the second SOC can be selected by the control unit 120, and it can be such that the multiple arcs included in the multiple EIS curves can be distinguished as negative arcing and positive arcing.

[0092] That is, the standard SOC range can be such that it is induced such that multiple arcs included in the corresponding EIS curve can be distinguished as negative arcing and positive arcing.

[0093] In one embodiment, the control unit 120 may be configured to select a negative electrode flat zone of the battery in the battery curve and set the selected negative electrode flat zone as the standard SOC zone.

[0094] Figure 4 This is a schematic diagram illustrating the battery curve BP according to one embodiment of the present disclosure.

[0095] Specifically, the battery curve BP can be a curve configured to represent the relationship between the battery's state of charge (SOC) and voltage. Specifically, the battery curve BP can include the battery's positive electrode curve PP, negative electrode curve NP, and full-cell curve FP.

[0096] Furthermore, the control unit 120 can determine the negative electrode flattening range in the negative electrode curve NP of the battery curve BP. Here, the negative electrode flattening range can refer to a range in which, even if the battery's SOC increases, the negative electrode voltage of the battery remains the same or varies within a predetermined range. That is, the negative electrode flattening range refers to the range in which the negative electrode voltage does not change or hardly changes even if the battery's SOC increases.

[0097] Generally speaking, the negative electrode flat zone may appear at approximately 50% SOC or above.

[0098] For example, in Figure 4 In this implementation, referring to the negative electrode curve NP, the negative electrode flat range can be the TSOC% to 100% range based on SOC. Therefore, the control unit 120 can be configured to set the TSOC% to 100% SOC range as the standard SOC range F.

[0099] Furthermore, when the control unit 120 selects multiple SOCs included in the standard SOC range F, the EIS unit 110 can generate multiple EIS curves based on the multiple SOCs (or their corresponding voltages) selected by the control unit 120.

[0100] Therefore, since multiple EIS curves are generated taking into account the flat region of the negative electrode, the multiple arcs included in the multiple EIS curves can be specifically distinguished as negative electrode arcs where the resistance change rate is equal to or less than the standard change rate and positive electrode arcs where the resistance change rate exceeds the standard change rate.

[0101] That is, since the battery management device according to one embodiment of the present disclosure generates multiple EIS curves taking into account the flat region of the negative electrode which is less affected by the negative electrode, the advantage is that the multiple arcs included in the multiple EIS curves can be specifically distinguished as negative electrode arcing and positive electrode arcing.

[0102] In another embodiment, the control unit 120 may be configured to determine a target peak in the differential curve and set the SOC range that is equal to or greater than the SOC corresponding to the determined target peak as the standard SOC range.

[0103] Figure 5 This is a schematic diagram illustrating a differential curve DP according to one embodiment of the present disclosure. The differential curve DP may be a curve representing the relationship between the state of charge (SOC) of the battery and the differential voltage (dV / dSOC) of the SOC.

[0104] The differential curve DP can include multiple peaks. Here, a peak is a point in the differential curve DP where the instantaneous rate of change of the differential voltage relative to the state of charge (SOC) is 0, and can be a point where the instantaneous rate of change changes from positive to negative based on the peak value. That is, the peak can be a point in the differential curve DP with an upward convex shape.

[0105] The control unit 120 can determine the target peak TP as the peak value that falls within a specific SOC range among the multiple peak values ​​included in the differential curve DP. If, among the multiple peak values ​​included in the differential curve DP, a peak value falls within a specific SOC range, the control unit 120 can determine the peak value with the largest corresponding differential voltage as the target peak TP.

[0106] Specifically, the specific SOC range can be preset to include the SOC at the beginning of the flat region of the negative electrode in the negative electrode curve NP of the battery. Preferably, the control unit 120 can be configured to determine the peak value with the maximum differential voltage in the SOC range of 40% to 100% of the differential curve as the target peak value TP. More preferably, the control unit 120 can be configured to determine the target peak value TP in the SOC range of 40% to 70%.

[0107] For example, in Figure 5 In this implementation, the target peak value TP can be determined from the SOC of TSOC% in the differential curve DP. Furthermore, the control unit 120 can set the SOC range from TSOC% to 100% as the standard SOC range F.

[0108] Specifically, the SOC corresponding to the target peak TP of the differential curve DP can correspond to the SOC at the beginning of the negative electrode flat section of the negative electrode curve NP. Therefore, when the control unit 120 cannot obtain the negative electrode curve NP of the battery, it can set the standard SOC range F by determining the target peak TP in the differential curve DP of the battery.

[0109] For example, when a battery is installed in an electric vehicle or energy storage system (ESS), it may not be possible to obtain the battery's negative electrode profile (NP) in a non-destructive manner. Therefore, the control unit 120 can set a standard state of charge (SOC) range (F) by determining the target peak value (TP) in the battery's differential profile (DP).

[0110] That is, since the standard SOC range F is set even in the differential curve DP, taking into account the flat range of the negative electrode of the battery, the multiple arcs included in multiple EIS curves can be specifically distinguished as negative electrode arcs with a resistance change rate less than or equal to the standard change rate and positive electrode arcs with a resistance change rate exceeding the standard change rate.

[0111] More preferably, the control unit 120 can set a standard SOC taking into account both the battery curve BP and the differential curve DP.

[0112] For example, the control unit 120 can select a first SOC range based on the flat region of the negative electrode in the negative electrode curve NP of the battery. Furthermore, the control unit 120 can select a second SOC range based on the target peak value TP in the differential curve DP.

[0113] Furthermore, when the first SOC range and the second SOC range are the same, the control unit 120 can set the first SOC range (or the second SOC range) as the standard SOC range F.

[0114] If the first SOC range and the second SOC range are not the same, the control unit 120 can set the second SOC range as the standard SOC range F.

[0115] For example, in Figure 5 In this implementation, since the target peak TP is the point where the instantaneous rate of change of the differential voltage relative to the SOC is 0, the error in calculating the SOC (TSOC) corresponding to the target peak TP can be very small. On the other hand, in Figure 4 In the implementation of this method, the error in determining the initial SOC of the negative electrode flat region in the negative electrode curve NP may be greater than the error in determining the SOC (TSOC) corresponding to the target peak value TP.

[0116] Therefore, when the first SOC interval based on the negative electrode curve NP and the second SOC interval based on the differential curve DP are different from each other, the control unit 120 can more accurately set the standard SOC interval F based on the target peak value TP included in the differential curve DP.

[0117] The battery management device 100 according to this disclosure can be applied to a BMS (Battery Management System). That is, the BMS according to this disclosure may include the battery management device 100 described above. In this configuration, at least some components of the battery management device 100 can be implemented by supplementing or adding functions included in the configuration of a conventional BMS. For example, the EIS unit 110, the control unit 120, and the storage unit 130 can be implemented as components of the BMS.

[0118] Furthermore, the battery management device 100 according to this disclosure can be disposed in a battery pack. That is, the battery pack according to this disclosure may include the aforementioned battery management device 100 and one or more battery cells. In addition, the battery pack may further include electrical devices (relays, fuses, etc.) and a housing.

[0119] Figure 6This is a diagram schematically illustrating an exemplary configuration of a battery pack 10 according to another embodiment of the present disclosure.

[0120] refer to Figure 6 The battery pack 10 may include a battery management device 100, a charging and discharging unit 200, a measurement unit 300, and a curve generation unit 400.

[0121] The charge / discharge unit 200 can be configured to connect to the high-current path of the battery pack 10 to charge and / or discharge the battery B.

[0122] For example, in Figure 6 In one embodiment, the charging and discharging unit 200 can be connected at one end between the positive terminal of battery B and the positive terminal P+ of battery pack 10, and at the other end between the negative terminal of battery B and the negative terminal P- of battery pack 10.

[0123] The measuring unit 300 can be connected to both ends of the battery B and configured to measure the voltage of the battery B.

[0124] For example, the measurement unit 300 can be connected to the positive terminal of battery B via a first sensing line SL1 and to the negative terminal of battery B via a second sensing line SL2. The measurement unit 300 can measure the positive terminal voltage of battery B via the first sensing line SL1 and measure the negative terminal voltage of battery B via the second sensing line SL2. Furthermore, the measurement unit 300 can measure the voltage of battery B by calculating the difference between the measured positive terminal voltage and the measured negative terminal voltage.

[0125] Furthermore, the measuring unit 300 can be connected to the ampere measuring unit A via a third sensing line SL3 to measure the current of the battery B. For example, the ampere measuring unit A can be a shunt resistor or an ammeter.

[0126] The curve generation unit 400 can receive information about the voltage and current of battery B from the measurement unit 300, and generate a battery curve BP and a differential curve DP based on the received information about battery B. The battery curve BP and differential curve DP generated by the curve generation unit 400 can be transmitted to the control unit 120 or stored in the storage unit 130.

[0127] Figure 7 This is a schematic diagram illustrating a battery management method according to another embodiment of the present disclosure.

[0128] Preferably, each step of the battery management method can be performed by a battery management device. In the following text, content overlapping with the foregoing description will be omitted or briefly described.

[0129] refer to Figure 7The battery management method may include an EIS curve generation step (S100), an arc resistance value calculation step (S200), a resistance change rate calculation step (S300), and an arc analysis step (S400).

[0130] The EIS curve generation step (S100) is a step in which AC current is output to the battery at multiple time points and an EIS curve representing the battery resistance is generated as a correspondence between the real and imaginary parts at each of the multiple time points, and this step can be performed by the EIS unit 110.

[0131] For example, refer to Figure 2 The EIS unit 110 can generate the first EIS curve of the battery at the first time point. Additionally, refer to... Figure 3 The EIS unit 110 can generate a second EIS curve of the battery at a second time point later than the first time point.

[0132] The arc resistance value calculation step (S200) is a step that determines multiple arcs in each of the multiple EIS curves generated in the EIS curve generation step (S100) and calculates the arc resistance value of each of the determined multiple arcs, and this step can be performed by the control unit 120.

[0133] First, the control unit 120 can determine the number of arcs in each of the multiple EIS curves. Furthermore, the control unit 120 can calculate the arc resistance value of the arcs included in each of the multiple EIS curves by using the EIS curves, an equivalent circuit model corresponding to the number of arcs, and a curve fitting algorithm.

[0134] For example, in Figure 2 In this implementation, the first EIS curve may include a first arc and a second arc based on R1. Furthermore, the resistance value of the first arc can be calculated to be 3mΩ, and the resistance value of the second arc can be calculated to be 21mΩ.

[0135] In addition, Figure 3 In this implementation, the second EIS curve may also include a first arc and a second arc based on R1. Furthermore, the resistance value of the first arc can be calculated to be 4mΩ, and the resistance value of the second arc can be calculated to be 122mΩ.

[0136] The resistance change rate calculation step (S300) is a step of calculating the resistance change rate between corresponding arcs in multiple arcs, and can be performed by the control unit 120.

[0137] The control unit 120 can calculate the rate of change of resistance between the arc resistance values ​​of the first arc and the rate of change of resistance between the arc resistance values ​​of the second arc.

[0138] For example, the resistance change rate between the first arc resistance value (3mΩ) of the first EIS curve and the first arc resistance value (4mΩ) of the second EIS curve can be calculated to be 1.3. Furthermore, the resistance change rate between the second arc resistance value (21mΩ) of the first EIS curve and the second arc resistance value (122mΩ) of the second EIS curve can be calculated to be 5.9.

[0139] The arc analysis step (S400) is a step in which each of the multiple arcs is determined to be either a negative arc or a positive arc based on multiple calculated resistance change rates and a preset standard change rate, and this step can be performed by the control unit 120.

[0140] Specifically, the control unit 120 can compare the magnitudes of multiple calculated rates of resistance change with a standard rate of change. Furthermore, the control unit 120 can set the rate of resistance change that is equal to or less than the standard rate of change as a first rate of resistance change, and the rate of resistance change that is greater than the standard rate of change as a second rate of resistance change. Finally, the control unit 120 can determine the arc corresponding to the first rate of resistance change as the negative arc and the arc corresponding to the second rate of resistance change as the positive arc.

[0141] In the EIS curve generation step (S100) of the battery management method according to one embodiment of the present disclosure, the multiple time points for generating multiple EIS curves can be selected based on a standard SOC range F, in which the effect of negative electrode degradation is minimized. Therefore, this battery management method has the advantage of more accurately distinguishing between negative electrode arcing and positive electrode arcing in the EIS curves.

[0142] The embodiments described above can be implemented not only by devices and methods, but also by a program or a recording medium that implements functions corresponding to the construction of the embodiments of this disclosure. Such a program or recording medium can be readily implemented by those skilled in the art based on the description of the embodiments above.

[0143] This disclosure has been described in detail. However, it should be understood that while the detailed description and specific embodiments illustrate preferred embodiments of this disclosure, they are given by way of illustration only, as various variations and modifications within the scope of this disclosure will become apparent to those skilled in the art from the detailed description.

[0144] Furthermore, those skilled in the art can make many substitutions, modifications and alterations to the present disclosure without departing from its technical aspects, and the present disclosure is not limited to the above-described embodiments and drawings. Each embodiment can be selectively combined in part or in whole to achieve various variations.

[0145] (See attached image labels)

[0146] 10: Battery Pack

[0147] 100: Battery Management Device

[0148] 110: EIS Unit

[0149] 120: Control Unit

[0150] 130: Storage unit

[0151] 200: Charge / Discharge Unit

[0152] 300: Measurement Unit

[0153] 400: Curve generation unit

Claims

1. A battery management device, the battery management device comprising: An EIS unit is configured to output AC current to the battery at multiple time points and generate multiple EIS curves representing the resistance of the battery as a correspondence between the real and imaginary parts at each of the multiple time points. as well as A control unit is configured to obtain the plurality of EIS curves of the battery generated by the EIS unit, determine a plurality of arcs in each of the plurality of EIS curves, calculate the arc resistance value of each of the determined plurality of arcs, calculate the resistance change rate of the arc resistance values ​​between corresponding arcs in the plurality of arcs, and, based on the calculated plurality of resistance change rates and a preset standard change rate, determine each of the plurality of arcs as either a negative electrode arc or a positive electrode arc. The multiple arcs are distinguished into negative arcs where the resistance change rate is equal to or less than the standard change rate, and positive arcs where the resistance change rate exceeds the standard change rate.

2. The battery management device according to claim 1, wherein The control unit is configured to set the resistance change rate that is equal to or less than the standard change rate among the plurality of resistance change rates as the first resistance change rate, and set the remaining resistance change rates as the second resistance change rate.

3. The battery management device according to claim 2, wherein The control unit is configured to identify multiple arcs in the plurality of EIS curves corresponding to the first resistance change rate as the negative electrode arc initiation, and to identify multiple arcs in the plurality of EIS curves corresponding to the second resistance change rate as the positive electrode arc initiation.

4. The battery management device according to claim 1, wherein, The control unit is configured to obtain at least one of a battery curve representing the correspondence between the SOC and voltage of the battery and a differential curve representing the correspondence between the SOC and the differential voltage relative to the SOC, and to set a standard SOC range based on the battery curve and the at least one of the differential curves.

5. The battery management device according to claim 4, wherein The control unit is configured to select a first SOC and a second SOC within a set standard SOC range, and The EIS unit is configured to generate an EIS curve for a battery in a first state corresponding to the first SOC, and to generate an EIS curve for a battery in a second state corresponding to the second SOC.

6. The battery management device according to claim 4, wherein The control unit is configured to select a first SOC and a second SOC within the set standard SOC range, determine a first voltage corresponding to the first SOC, and determine a second voltage corresponding to the second SOC. The EIS unit is configured to generate an EIS curve for a battery in a first state corresponding to the first SOC, and to generate an EIS curve for a battery in a second state corresponding to the second SOC.

7. The battery management device according to claim 4, wherein The control unit is configured to select the negative electrode flat range of the battery in the battery curve and set the selected negative electrode flat range as the standard SOC range.

8. The battery management device according to claim 4, wherein The control unit is configured to determine a target peak value in the differential curve and set the SOC interval that is equal to or greater than the SOC corresponding to the determined target peak value as the standard SOC interval.

9. The battery management device according to claim 8, in, The control unit is configured to determine the peak value with the maximum differential voltage in the SOC range of 40% to 100% of the differential curve as the target peak value.

10. The battery management device according to claim 1, in, The EIS unit is configured to generate the plurality of EIS curves within one charge-discharge cycle of the battery.

11. The battery management device according to claim 4, in, The multiple time points used to generate the multiple EIS curves are selected based on the standard SOC interval.

12. A battery pack comprising a battery management device according to any one of claims 1 to 11.

13. A battery management method, the battery management method comprising: The EIS curve generation step outputs AC current to the battery at multiple time points and generates multiple EIS curves representing the resistance of the battery as the correspondence between the real and imaginary parts at each of the multiple time points. The arc resistance value calculation step determines multiple arcs in each of the plurality of EIS curves generated in the EIS curve generation step, and calculates the arc resistance value of each of the determined plurality of arcs. The resistance change rate calculation step calculates the resistance change rate between corresponding arcs in the plurality of arcs; as well as The arc analysis step, based on calculated multiple resistance change rates and a preset standard change rate, determines each of the multiple arcs as either a negative or positive arc initiation. The multiple arcs are distinguished into negative arcs where the resistance change rate is equal to or less than the standard change rate, and positive arcs where the resistance change rate exceeds the standard change rate.

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