Battery diagnostic device and method

Abstract

A battery diagnostic method according to an embodiment of the present invention is to diagnose a battery assembly including a battery bank provided by connecting a plurality of battery cells in parallel to each other, the battery diagnostic method comprising: a secondary differential profile generation step for generating a secondary differential profile indicating the relationship between a secondary differential capacity and the voltage of the battery bank, the secondary differential capacity being obtained by secondarily differentiating the capacity of the battery bank with respect to the voltage of the battery bank; and a diagnosis step for detecting a target peak located in a predetermined voltage section from among a plurality of peaks of the secondary differential profile so as to diagnose the state of the battery bank on the basis of a secondary differential capacity value of the target peak.

Description

Battery diagnostic device and method

[0001] This application claims priority from Korean Patent Application No. 10-2024-0019807, filed February 8, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a battery diagnostic device and method, and more particularly, to a battery diagnostic device and method for non-destructively diagnosing a rechargeable battery.

[0003] Recently, as the demand for portable electronic products such as laptops, digital cameras, and mobile phones has rapidly increased, and the development of electric vehicles, energy storage systems, robots, and satellites has been in full swing, research on high-performance, rechargeable, and high-energy-density batteries is actively being conducted.

[0004] Rechargeable batteries include lithium batteries that utilize lithium ions, such as lithium-ion batteries and lithium-ion polymer batteries, as well as nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries. Among these, lithium batteries offer a relatively long lifespan due to minimal memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density. Consequently, their application scope is gradually expanding.

[0005] The positive and negative electrodes of these batteries gradually deteriorate as they undergo repeated charge and discharge cycles, losing their original electrical capacity. Therefore, accurate diagnosis of battery condition is essential to accurately predict the battery's usable lifespan, remaining service life, and replacement timing.

[0006] However, existing technologies diagnose battery assemblies (e.g., battery modules or battery packs) that include multiple battery cells, which are the basic units of charge and discharge, based on the SOH (State of Health) of the battery assembly. Therefore, when a battery assembly includes multiple battery banks, each of which is formed by connecting multiple battery cells in parallel, existing technologies have the problem of not being able to diagnose the state of the battery assembly for each battery bank, and not being able to diagnose whether the battery cells of each battery bank are deteriorating unevenly.

[0007] The technical problem to be solved by the present invention is to provide a battery diagnosis device and method capable of diagnosing the state of a battery assembly including a plurality of battery banks formed by connecting a plurality of battery cells in parallel, for each battery bank, and diagnosing whether the battery cells of each battery bank are deteriorating unevenly.

[0008] Another technical problem to be solved by the present invention is to provide a battery diagnostic device and method capable of extending the life of a battery assembly and improving safety.

[0009] A battery diagnosis method according to one aspect of the present invention is a method for diagnosing a battery assembly including a battery bank formed by connecting a plurality of battery cells in parallel, the method comprising: a second differential profile generation step of generating a second differential profile indicating a relationship between a second differential capacity obtained by second differentiating a capacity of the battery bank with respect to a voltage of the battery bank and a voltage of the battery bank; and a diagnosis step of detecting a target peak located in a predetermined voltage range among a plurality of peaks of the second differential profile, and diagnosing a state of the battery bank based on a second differential capacity value of the target peak.

[0010] In one embodiment, the second differential profile generation step may include the steps of repeatedly measuring a voltage value and a current value of the battery bank using at least one electrical sensor while the battery bank is being charged or discharged; and the steps of generating the second differential profile using the voltage values ​​and current values ​​measured while the battery bank is being charged or discharged.

[0011] In one embodiment, the second differential profile generation step may include: generating a profile representing a relationship between a voltage and a capacity of the battery bank; differentiating the profile with respect to the voltage of the battery bank to generate a first differential profile; and differentiating the first differential profile with respect to the voltage of the battery bank to generate the second differential profile.

[0012] In one embodiment, the diagnosis step may include a step of comparing the second differential capacity value of the target peak with a predetermined threshold value, and diagnosing the state of the battery bank as abnormal if the second differential capacity value is less than the threshold value.

[0013] In one embodiment, the diagnosis step may include a step of diagnosing the state of the battery bank as an abnormal state in which the plurality of battery cells are unevenly deteriorated, when the second differential capacity value of the target peak is less than a predetermined threshold value and the number of target peaks located in the predetermined voltage section exceeds a predetermined reference number.

[0014] In one embodiment, the battery assembly may include a plurality of battery banks, and the second differential profile generation step may include a step of generating a plurality of second differential profiles each corresponding to a plurality of battery banks included in the battery assembly, and the diagnosis step may include a step of diagnosing a state of each of the plurality of battery banks as a normal state or an abnormal state based on the plurality of second differential profiles.

[0015] In one embodiment, the diagnosis step includes a step of diagnosing the state of the battery bank as abnormal when the second differential capacity value of the target peak is smaller than a predetermined threshold value, and the battery diagnosis method may further include a step of controlling a charger that charges the battery bank to reduce a voltage when charging of the battery bank is completed or reduce a current rate of a current that charges the battery bank when the state of the battery bank is diagnosed as abnormal.

[0016] According to another aspect of the present invention, a battery diagnosis device is a device for diagnosing a battery assembly including a battery bank formed by connecting a plurality of battery cells in parallel, the device including a second differential profile generation unit for generating a second differential profile indicating a relationship between a second differential capacity obtained by second differentiating a capacity of the battery bank with respect to a voltage of the battery bank and a voltage of the battery bank; and a diagnosis unit for detecting a target peak located in a predetermined voltage range among a plurality of peaks of the second differential profile and diagnosing a state of the battery bank based on a second differential capacity value of the target peak.

[0017] In one embodiment, the diagnostic unit may be configured to compare the second differential capacity value of the target peak with a predetermined threshold value, and diagnose the state of the battery bank as abnormal if the second differential capacity value is less than the threshold value.

[0018] In one embodiment, the diagnostic unit may be configured to diagnose the state of the battery bank as an abnormal state in which the plurality of battery cells are unevenly deteriorated, when the second differential capacity value of the target peak is less than a predetermined threshold value and the number of target peaks located in the predetermined voltage section exceeds a predetermined reference number.

[0019] In one embodiment, the battery assembly includes a plurality of battery banks, the second differential profile generation unit is configured to generate a plurality of second differential profiles corresponding to each of the plurality of battery banks included in the battery assembly, and the diagnosis unit may be configured to diagnose the state of each of the plurality of battery banks as a normal state or an abnormal state based on the plurality of second differential profiles.

[0020] In one embodiment, the diagnostic unit is configured to diagnose the state of the battery bank as abnormal when the second differential capacity value of the target peak is smaller than a predetermined threshold value, and the battery diagnostic device may further include a battery management unit configured to control a charger that charges the battery bank to reduce a voltage upon completion of charging of the battery bank or reduce a current rate of a current that charges the battery bank when the state of the battery bank is diagnosed as abnormal.

[0021] A battery pack according to another aspect of the present invention includes the battery diagnostic device described above.

[0022] A vehicle according to another aspect of the present invention includes the battery diagnostic device described above.

[0023] The present invention diagnoses the state of a battery bank by using a second derivative profile representing the relationship between the second derivative capacity obtained by second-differentiating the capacity of a battery bank included in a battery assembly with respect to the voltage of the battery bank and the voltage of the battery bank, thereby enabling the state of a battery assembly including a plurality of battery banks to be diagnosed for each battery bank, and improving the accuracy and reliability of the diagnosis result.

[0024] In addition, the present invention diagnoses the state of the battery bank based on the second differential capacity value of a target peak located in a predetermined voltage range among a plurality of peaks of the second differential profile, thereby accurately diagnosing whether battery cells in a battery bank prepared by connecting battery cells in parallel are deteriorated unevenly.

[0025] In addition, the present invention can manage a battery assembly including multiple battery banks by controlling the charging and / or discharging conditions of the battery bank according to the diagnosis results of the battery bank, thereby extending the lifespan of the entire battery assembly and improving safety.

[0026] Furthermore, those skilled in the art will readily understand from the following description that various embodiments of the present invention can solve various technical problems not mentioned above.

[0027] FIG. 1 is a block diagram showing a battery diagnostic device according to one embodiment of the present invention.

[0028] Figure 2 is a drawing showing an example of a battery assembly that is a diagnostic target of the present invention.

[0029] Figure 3 is a drawing showing an example of a profile showing the relationship between the capacity and voltage of a battery bank.

[0030] Figure 4 is a diagram showing the first-order differential profile of a normal battery bank.

[0031] Figure 5 is a diagram showing the second-order differential profile of a normal battery bank.

[0032] Figure 6 is a diagram showing the first-order differential profile of an abnormal battery bank.

[0033] Figure 7 is a diagram showing the second-order differential profile of an abnormal battery bank.

[0034] Figure 8 is a graph showing the change in the second differential capacity value of the first target peak due to uneven deterioration of the battery bank.

[0035] Figure 9 is a graph showing the change in the second differential capacity value of the second target peak due to uneven deterioration of the battery bank.

[0036] Fig. 10 is a flowchart illustrating a battery diagnosis method according to one embodiment of the present invention.

[0037] FIG. 11 is a drawing showing a battery pack according to one embodiment of the present invention.

[0038] Fig. 12 is a drawing showing a vehicle according to one embodiment of the present invention.

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings to clarify solutions corresponding to the technical challenges of the present invention. However, when describing the present invention, descriptions of related known technologies may be omitted if they obscure the gist of the present invention. Furthermore, the terms used in this specification are defined in consideration of their functions in the present invention, and these may vary depending on the intentions or practices of designers, manufacturers, etc. Therefore, the definitions of terms described below should be based on the contents throughout this specification.

[0040] FIG. 1 is a block diagram showing a battery diagnostic device (100) according to one embodiment of the present invention.

[0041] As illustrated in FIG. 1, a battery diagnostic device (100) according to one embodiment of the present invention includes a control unit (110). The control unit (110) is configured to non-destructively diagnose a battery assembly including one or more battery banks formed by connecting a plurality of rechargeable battery cells in parallel.

[0042] To this end, the control unit (110) may include one or more general-purpose processors or application-specific integrated circuits (ASICs) for executing battery diagnosis logic, and may optionally further include hardware such as registers and memories depending on the embodiment. The control unit (110) may be configured with a combination of hardware such as a processor and software such as a computer program. That is, the battery diagnosis logic of the control unit (110) may be configured as a computer program and stored in the control unit's (110) own memory or the storage unit (140) described below, and the stored computer program may be configured to be executed through the hardware of the control unit (110).

[0043] Meanwhile, the control unit (110) includes a second differential profile generation unit (112) and a diagnosis unit (114) as detailed components for diagnosing the battery assembly.

[0044] The above second differential profile generation unit (112) is configured to generate a second differential profile representing the relationship between the second differential capacity obtained by second differentiating the capacity of a battery bank included in a battery assembly with respect to the voltage of the battery bank, and the voltage of the battery bank.

[0045] In one embodiment, the second differential profile generation unit (112) may include a measurement module (112a), a first generation module (112b), and a second generation module (112c).

[0046] In this case, the measurement module (112a) may be configured to repeatedly measure the voltage value and current value of the battery bank using at least one electrical sensor while the battery bank is being charged or discharged.

[0047] The first generation module (112b) and the second generation module (112c) can generate the second differential profile using voltage values ​​and current values ​​measured by the measurement module (112a) while the battery bank is being charged or discharged.

[0048] For example, the first generation module (112b) may be configured to generate a profile representing the relationship between the voltage and capacity of the battery bank using voltage values ​​and current values ​​measured while the battery bank is being charged or discharged.

[0049] The second generation module (112c) may be configured to generate a first differential profile by differentiating the generated profile with respect to the voltage of the battery bank, and to generate the second differential profile by differentiating the first differential profile again with respect to the voltage of the battery bank.

[0050] The above diagnostic unit (114) is configured to detect a target peak located in a predetermined voltage range among a plurality of peaks of the second differential profile, and to diagnose the state of the battery bank based on the second differential capacity value of the target peak.

[0051] The voltage interval where the target peak is located can be experimentally determined. That is, the voltage interval where splitting occurs due to uneven discharge of the battery bank among the peaks of the second-order differential profile can be experimentally confirmed, and the confirmed voltage interval can be determined as the voltage interval where the target peak is located.

[0052] In one embodiment, the diagnostic unit (114) may be configured to compare the second differential capacity value of the target peak with a predetermined threshold value, and diagnose the state of the battery bank as abnormal if the second differential capacity value is less than the threshold value. In this case, the abnormal state may mean a state in which a plurality of battery cells constituting the battery bank are unevenly deteriorated.

[0053] The above threshold value may be the minimum value among the second-order differential capacity values ​​that the target peak of the normal battery bank may have, or a value determined during the design of the battery assembly.

[0054] In another embodiment, the diagnostic unit (114) may be configured to diagnose the state of the battery bank as abnormal if the second differential capacity value of the target peak is less than a predetermined threshold value and the number of target peaks located in the predetermined voltage range exceeds a predetermined reference number. In this case, the abnormal state may mean a state in which a plurality of battery cells constituting the battery bank are unevenly deteriorated.

[0055] In another embodiment, the diagnostic unit (114) may be configured to determine the status of the battery bank based on a plurality of target peaks.

[0056] In this case, the diagnostic unit (114) may be configured to detect a first target peak located in a first voltage section and a second target peak located in a second voltage section among predetermined voltage sections.

[0057] In addition, the diagnostic unit (114) may be configured to determine the state of the battery bank as abnormal when the second differential capacity value of the first target peak is less than a first predetermined threshold value and the second differential capacity value of the second target peak is less than a second predetermined threshold value. In this case, the abnormal state may mean a state in which a plurality of battery cells included in the battery bank are unevenly deteriorated.

[0058] In one embodiment, when the battery assembly to be diagnosed includes a plurality of battery banks, the second differential profile generation unit (112) may be configured to generate a plurality of second differential profiles corresponding to each of the plurality of battery banks.

[0059] In this case, the diagnostic unit (114) may be configured to diagnose the state of each of the plurality of battery banks as a normal state or an abnormal state based on the plurality of second-order differential profiles.

[0060] In one embodiment, the control unit (110) may further include a diagnosis result notification unit (116). In this case, the diagnosis result notification unit (116) may be configured to output a visual, auditory, or audiovisual notification signal corresponding to the diagnosis result of the battery bank using a predetermined output device.

[0061] In one embodiment, the control unit (110) may further include a battery management unit (118). In this case, the battery management unit (118) may be configured to adjust charging conditions and / or discharging conditions of the battery bank based on a diagnosis result for the battery bank.

[0062] For example, when an abnormal battery bank diagnosed as abnormal by the diagnostic unit (114) among a plurality of battery banks included in the battery assembly is detected, the battery management unit (118) may be configured to control a charger that charges the abnormal battery bank to reduce the voltage upon completion of charging of the abnormal battery bank or reduce the current rate of the current that charges the abnormal battery bank.

[0063] Meanwhile, the battery management unit (118b) may be configured to control the cooling device (18) described later to lower the temperature of the abnormal battery bank.

[0064] The second derivative profile generation unit (112), diagnosis unit (114), diagnosis result notification unit (116), and battery management unit (118) of the above-described control unit (110) may be implemented as a combination of a processor and a program executed by the processor. In this case, the control unit (110) may be implemented as a single processor or as two or more processors that are interconnected.

[0065] In one embodiment, the battery diagnostic device (100) may further include a communication unit (120). The communication unit (120) may be configured to receive data transmitted from a remotely located server or communication terminal via a wired and / or wireless communication network and transmit the data to the control unit (110), or transmit control signals, diagnostic data, etc. processed by the control unit (110) to the remotely located server or communication terminal. To this end, the communication unit (120) may include a communication modem that performs wired communication and / or wireless communication.

[0066] In one embodiment, the battery diagnostic device (100) may further include an input unit (130). The input unit (130) may be configured to receive commands or data from a user or administrator. To this end, the input unit (130) may include an input device such as a keyboard, operation buttons, or a touch panel.

[0067] In one embodiment, the battery diagnostic device (100) may further include a storage unit (140). The storage unit (140) may be configured to store and manage data necessary for the operation of the battery diagnostic device (100). To this end, the storage unit (140) may include one or two or more of a ROM, a RAM, an EEPROM, a register, a flash memory, a CD-ROM, a magnetic tape, a hard disk, a floppy disk, and an optical data recording device.

[0068] In one embodiment, the battery diagnostic device (100) may further include an output unit (150). The output unit (150) may be configured to visually, audibly, or audiovisually output a notification signal of the diagnostic result notification unit (116). To this end, the output unit (150) may include a visual output device such as a light-emitting diode, a monitor, a display panel, or a touch screen. In addition, the output unit (150) may further include a sound generating device such as a speaker.

[0069] In one embodiment, the battery diagnostic device (100) may be configured to be linked to a measuring device (12) that measures the voltage and / or current of a battery assembly to be diagnosed, a communication device (14) that communicates with another device, a charging / discharging device (16) that charges / discharges battery banks included in the battery assembly, and a cooling device (18) that cools battery banks included in the battery assembly.

[0070] In another embodiment, the battery diagnostic device (100) according to the present invention may include one or two or more of the above-described measuring device (12), communication device (14), charging / discharging device (16), and cooling device (18).

[0071] FIG. 2 is a drawing showing an example of a battery assembly (BA) that is a diagnostic target of the present invention.

[0072] As illustrated in FIG. 2, the battery assembly (BA) to be diagnosed according to the present invention may include a plurality of battery banks (BB1 to BBn). In this case, the plurality of battery banks (BB1 to BBn) may be connected in series with each other or in a hybrid of series and parallel connections. Furthermore, each battery bank may include a plurality of battery cells (BC) connected in parallel with each other.

[0073] Such a battery assembly (BA) may be implemented as a battery module or battery pack including battery banks and a case that accommodates the battery banks.

[0074] As such, since the multiple battery cells (BCs) included in each battery bank are connected in parallel, it is difficult to measure the voltage of each battery cell. Therefore, existing technologies that estimate the SOC or SOH of a battery assembly using parameters such as voltage, current, and temperature of the entire battery assembly as parameters cannot diagnose the condition of the battery assembly for each battery bank, nor can they determine whether the battery cells of the aforementioned battery banks are deteriorating unevenly.

[0075] On the other hand, the battery diagnosis device (100) according to the present invention measures the voltage (V1) and current (I1) of the battery bank (BB1) while the battery bank (BB1) is being charged or discharged, generates a profile indicating the relationship between the voltage and capacity of the battery bank (BB1), and diagnoses the state of the battery bank using the second differential profile obtained by second differentiating this profile, thereby diagnosing the state of the battery assembly for each battery bank and accurately determining whether the battery cells of the battery bank are deteriorating unevenly.

[0076] Figure 3 is a drawing showing an example of a profile showing the relationship between the capacity and voltage of a battery bank.

[0077] As illustrated in FIG. 3, the second differential profile generation unit (112) can generate a profile (BP) representing the relationship between the capacity and voltage of the battery bank (BB1) by measuring the electrical values ​​(V1, I1) of the battery bank (BB1) while the battery bank (BB1) of FIG. 2 is being charged or discharged. In this case, the capacity of the battery bank can be expressed as a State of Charge (SOC) value using a percentage (%) as a unit. For reference, the electric capacity of the battery bank (BB1) can be calculated by applying a current integration method to the current (I1) that charges the battery bank (BB1).

[0078] Meanwhile, the second differential profile generation unit (112) can find a positive profile (PP) and a negative profile (NP) that generate a curve similar to the profile (BP) through mutual combination, and provide the starting point (pi) and the ending point (pf) of the positive profile (PP), the shrinkage rate (ps) of the positive profile (PP) compared with the reference positive profile, the starting point (ni) and the ending point (nf) of the negative profile (NP), the shrinkage rate (ns) of the negative profile (NP) compared with the reference negative profile, etc. to the diagnosis unit (114). The diagnosis unit (114) can use the starting point (pi), the ending point (pf) and the shrinkage rate (ps) of the positive profile (PP), and the starting point (ni), the ending point (nf) and the shrinkage rate (ns) of the negative profile (NP) as diagnosis factors indicating the state of the battery bank (BB1).

[0079] In addition, the second differential profile generation unit (112) can generate the second differential profile by second differentiating the profile (BP) with respect to the voltage of the battery.

[0080] Figure 4 is a diagram showing the first-order differential profile (BP'1) of a normal battery bank.

[0081] As illustrated in FIG. 4, the second differential profile generation unit (112) can generate a first differential profile (BP'1) by differentiating a profile representing the relationship between the voltage and capacity of a battery bank charged at a current rate of 0.33 [C] with respect to the voltage of the battery bank.

[0082] In addition, the second differential profile generation unit (112) can generate a second differential profile by differentiating the first differential profile (BP'1) again with respect to the voltage of the battery bank.

[0083] Figure 5 is a diagram showing the second derivative profile (BP"1) of a normal battery bank.

[0084] As shown in Fig. 5, the second differential profile generation unit (112) generates a second differential capacity (d) by second differentiating the capacity of the battery bank with respect to the voltage of the battery bank. 2 Q / dV 2 ) and a second derivative profile (BP"1) representing the relationship between the voltage of the corresponding battery bank can be generated for each battery bank at a predetermined diagnostic cycle.

[0085] Then, the diagnostic unit (114) can diagnose the status of the corresponding battery bank based on the second differential capacity value of the target peak (Pa1) located in a predetermined voltage range (S1) among the multiple peaks of the second differential profile (DP1). For example, the voltage range (S1) may be a range from 3.45 [V] to 3.55 [V].

[0086] For example, if the second differential capacity value of the target peak (Pa1) is less than a predetermined threshold value, the diagnostic unit (114) can diagnose the state of the battery bank as abnormal. In this case, the abnormal state may mean a state in which a plurality of battery cells forming the battery bank are unevenly deteriorated.

[0087] The above threshold value may be the minimum value among the second-order differential capacity values ​​that the target peak of the normal battery bank may have, or a value determined during the design of the battery assembly.

[0088] In one embodiment, the diagnostic unit (114) may be configured to determine the status of the battery bank based on a plurality of target peaks.

[0089] In this case, the diagnostic unit (114) can detect a first target peak (Pa1) located in a first voltage section (S1) among predetermined voltage sections, and a second target peak (Pb1) located in a second voltage section (S2). For example, the first voltage section (S1) may be a section from 3.45 [V] to 3.55 [V], and the second voltage section (S2) may be a section from 3.60 [V] to 3.70 [V].

[0090] Next, the diagnostic unit (114) can determine the state of the battery bank as abnormal if the second differential capacity value of the first target peak (Pa1) is less than a first predetermined threshold value and the second differential capacity value of the second target peak (Pb1) is less than a second predetermined threshold value. The abnormal state may mean a state in which a plurality of battery cells of the battery bank are unevenly deteriorated.

[0091] Figure 6 is a diagram showing the first-order differential profile (BP'2) of an abnormal battery bank.

[0092] As illustrated in Fig. 6, the first differential profile (BP'2) of the abnormal battery bank in which battery cells are unevenly deteriorated exhibits a different pattern from the first differential profile (BP'1) of the normal battery bank illustrated in Fig. 4. That is, the first differential profile (BP'2) of the abnormal battery bank has a reduced slope change compared to the first differential profile (BP'1) of the normal battery bank.

[0093] Figure 7 is a diagram showing the second derivative profile (BP"2) of an abnormal battery bank.

[0094] As illustrated in FIG. 7, the second differential capacity value of the first target peak (Pa2) shown in the second differential profile (BP"2) of the abnormal battery bank in which the battery cells are unevenly deteriorated is reduced compared to the second differential capacity value of the first target peak (Pa1) shown in the second differential profile (BP"1) of the normal battery bank.

[0095] Similarly, the second differential capacity value of the second target peak (Pb2) appearing in the second differential profile (BP"2) of the abnormal battery bank is reduced compared to the second differential capacity value of the second target peak (Pb1) appearing in the second differential profile (BP"1) of the normal battery bank.

[0096] Accordingly, the diagnostic unit (114) can determine that the state of the corresponding battery bank is abnormal when the second differential capacity value of the first target peak (Pa2) is smaller than a predetermined first threshold value.

[0097] In another embodiment, the diagnostic unit (114) may determine the state of the battery bank as abnormal if the second differential capacity value of the first target peak (Pa2) is less than the first threshold value and the second differential capacity value of the second target peak (Pb2) is less than a predetermined second threshold value. In this case, the abnormal state may mean a state in which a plurality of battery cells of the battery bank are unevenly deteriorated.

[0098] Meanwhile, additional peaks (SPa, SPb) may occur around the first target peak (Pa2) and the second target peak (Pb2) of the second differential profile (BP"2) of the abnormal battery bank due to peak splitting caused by uneven deterioration of the battery bank.

[0099] Accordingly, the diagnostic unit (114) can diagnose the state of the battery bank as abnormal if at least one of the second differential capacity value of the first target peak (Pa2) and the second differential capacity value of the second target peak (Pb2) is smaller than a predetermined threshold value and the number of target peaks located in a predetermined voltage section (S1, S2) exceeds a predetermined reference number. In this case, the abnormal state may mean a state in which a plurality of battery cells of the battery bank are unevenly deteriorated.

[0100] Figure 8 is a graph showing the change in the second differential capacity value of the first target peak (Pa2) due to uneven deterioration of the battery bank.

[0101] As illustrated in FIG. 8, when the battery cells of the battery bank deteriorate unevenly, the second differential capacity value of the first target peak (Pa2) located in the first voltage section (S1) of the second differential profile (BP"2) gradually decreases over time.

[0102] In addition, when the second differential capacity value of the first target peak (Pa2) becomes smaller than the first threshold value (Qr"1) at a point (t1), a peak splitting phenomenon occurs in the first target peak (Pa2).

[0103] Figure 9 is a graph showing the change in the second differential capacity value of the second target peak (Pb2) due to uneven deterioration of the battery bank.

[0104] As illustrated in FIG. 9, when the battery cells of the battery bank deteriorate unevenly, the second differential capacity value of the second target peak (Pb2) located in the second voltage section (S2) of the second differential profile (BP"2) gradually decreases over time.

[0105] In addition, when the second differential capacity value of the second target peak (Pb2) becomes smaller than the second threshold value (Qr"2) at a point (t2), a peak splitting phenomenon occurs in the second target peak (Pb2).

[0106] Fig. 10 is a flowchart illustrating a battery diagnosis method according to one embodiment of the present invention.

[0107] As illustrated in FIG. 10, a battery diagnosis method according to the present invention is a method for non-destructively diagnosing a battery assembly including a battery bank prepared by connecting a plurality of battery cells in parallel, and can be performed by a processor.

[0108] First, the processor generates a second derivative profile representing the relationship between the second derivative capacity obtained by second differentiating the capacity of a battery bank included in a battery assembly with respect to the voltage of the battery bank and the voltage of the battery bank (S10).

[0109] In this case, the processor can repeatedly measure the voltage value and current value of the battery bank using at least one electrical sensor while the battery bank is being charged or discharged.

[0110] Next, the processor can generate the second derivative profile using the voltage values ​​and current values ​​measured while the battery bank is being charged or discharged.

[0111] For example, the processor may generate a profile representing the relationship between the voltage and capacity of the battery bank using voltage values ​​and current values ​​measured while the battery bank is being charged or discharged.

[0112] Next, the processor can differentiate the generated profile with respect to the voltage of the battery bank to generate a first differential profile, and can differentiate the first differential profile again with respect to the voltage of the battery bank to generate the second differential profile.

[0113] Next, the processor diagnoses the state of the battery bank based on the second differential capacity value of a target peak located in a predetermined voltage range among the plurality of peaks of the second differential profile.

[0114] That is, the processor detects a target peak located in the predetermined voltage range among the plurality of peaks of the second differential profile (S20).

[0115] The voltage interval where the target peak is located can be experimentally determined. That is, the voltage interval where splitting occurs due to uneven discharge of the battery bank among the peaks of the second-order differential profile can be experimentally confirmed, and the confirmed voltage interval can be determined as the voltage interval where the target peak is located.

[0116] Next, the processor can diagnose the state of the battery bank by comparing the second differential capacity value (Qp") of the target peak with a predetermined threshold value (Qr") (S30).

[0117] For example, the processor can diagnose the state of the battery bank as abnormal when the second differential capacity value (Qp") of the target peak is less than the threshold value (Qr") (S40). In this case, the abnormal state may mean a state in which a plurality of battery cells forming the battery bank are unevenly deteriorated.

[0118] The above threshold value may be the minimum value among the second-order differential capacity values ​​that the target peak of the normal battery bank may have, or a value determined during the design of the battery assembly.

[0119] In another embodiment, the processor may be configured to diagnose the state of the battery bank as abnormal if the second differential capacity value of the target peak is less than a predetermined threshold value and the number of target peaks located in the predetermined voltage range exceeds a predetermined reference number. In this case, the abnormal state may mean a state in which a plurality of battery cells constituting the battery bank are unevenly deteriorated.

[0120] In another embodiment, the processor may be configured to determine the state of the battery bank based on a plurality of target peaks.

[0121] In this case, the processor can detect a first target peak located in a first voltage section and a second target peak located in a second voltage section among predetermined voltage sections.

[0122] In addition, the processor may determine the state of the battery bank as abnormal when the second differential capacity value of the first target peak is less than a first predetermined threshold value and the second differential capacity value of the second target peak is less than a second predetermined threshold value. In this case, the abnormal state may mean a state in which a plurality of battery cells included in the battery bank are unevenly deteriorated.

[0123] Additionally, in one embodiment, when the battery assembly to be diagnosed includes a plurality of battery banks, the processor can generate a plurality of second-order differential profiles, each corresponding to a plurality of battery banks.

[0124] In this case, the processor can diagnose the status of each of the plurality of battery banks as normal or abnormal based on the plurality of second-order differential profiles.

[0125] Next, the processor can adjust the charging conditions and / or discharging conditions of the battery bank based on the diagnosis results for the battery bank (S50).

[0126] For example, when an abnormal battery bank diagnosed as abnormal is detected among a plurality of battery banks included in a battery assembly, the processor may control a charger that charges the abnormal battery bank to reduce a voltage upon completion of charging of the abnormal battery bank or reduce a current rate of a current that charges the abnormal battery bank.

[0127] Additionally, the processor may control a cooling device (18) described below to lower the temperature of the abnormal battery bank.

[0128] Meanwhile, the processor may output a visual, auditory or audiovisual notification signal corresponding to the diagnostic result regarding the battery bank using a predetermined output device.

[0129] Next, the processor may repeat the above-described steps (S10 to S50) until the use of the battery assembly is stopped (S60).

[0130] FIG. 11 is a drawing showing a battery pack (10) according to one embodiment of the present invention.

[0131] As illustrated in FIG. 11, the battery pack (10) includes a battery bank (BB) in which a plurality of battery cells are connected in parallel with each other, and a battery diagnostic device (100) according to the present invention. In one embodiment, the battery pack (10) may optionally further include a measuring device (12), a communication device (14), a charging / discharging device (16), and a cooling device (18).

[0132] The above measuring device (12) may be configured to measure the voltage and / or current of the battery bank (BB). To this end, the measuring device (12) may include at least one voltage sensor for sensing the voltage of the battery bank (BB) and / or at least one current sensor for sensing the current of the battery bank (BB).

[0133] This measuring device (12) can measure the voltage of the battery bank (BB) through the first sensing line (SL1) and the second sensing line (SL2). In addition, the measuring device (12) can measure the current of the battery bank (BB) through the third sensing line (SL3) connected to the current measuring circuit (A). The current measuring circuit (A) can include a shunt resistor.

[0134] A battery diagnostic device (100) according to one embodiment of the present invention can obtain voltage values ​​of a battery bank (BB) through the measuring device (12). For reference, the capacity of the battery bank (BB) can be calculated by applying a current integration method to the current charging the battery bank (BB).

[0135] The above communication unit (14) may be configured to perform communication with another device located remotely. For example, the communication unit (14) may be configured to receive data transmitted from a remote server or communication terminal via a wired and / or wireless communication network and transmit the data to the battery diagnosis device (100), or to transmit data generated in the battery diagnosis device (100) to another server or communication terminal. To this end, the communication unit (14) may include a communication modem that performs wired and / or wireless communication.

[0136] The above charging / discharging device (16) may be configured to charge and / or discharge the battery bank (BB). To this end, the charging / discharging device (16) may include a charger for charging the battery bank (BB), a discharger for discharging the battery bank (BB), at least one switch for electrically connecting the battery bank (BB) to terminals (T1, T2) of the battery pack (10), etc.

[0137] A battery diagnostic device (100) according to one embodiment of the present invention can control the charging / discharging device (16) to proceed with or stop charging or discharging of a battery bank (BB), set charging / discharging conditions, or change set charging / discharging conditions.

[0138] The cooling device (18) may be configured to cool the battery bank (BB). To this end, the cooling device (18) may include a heat sink that absorbs heat from the battery bank (BB) and releases it to the outside.

[0139] Fig. 11 is a drawing showing a vehicle according to one embodiment of the present invention.

[0140] As illustrated in FIG. 11, a vehicle (2) according to one embodiment of the present invention may include a battery pack (10) that provides electric energy required for the operation of the vehicle, and a battery diagnostic device (100) according to the present invention.

[0141] In this case, the battery diagnostic device (100) may be configured to be linked with an ECU (Electronic Control Unit) that controls the operation of the vehicle (2) or a BMS (Battery Management System) of the battery pack (10).

[0142] Additionally, the battery diagnostic device (100) may be configured to receive data transmitted from a remote server (4) via a wired and / or wireless communication network, or to transmit data generated in the battery diagnostic device (100) to the server (4).

[0143] For reference, the battery diagnostic device (100) according to the present invention can be applied to various electrical devices or electrical systems other than vehicles, and can also be applied to ESS (Energy Storage System).

[0144] As described above, the present invention diagnoses the state of a battery bank by using a second derivative profile representing the relationship between the second derivative capacity obtained by second-differentiating the capacity of a battery bank included in a battery assembly with respect to the voltage of the battery bank and the voltage of the battery bank, thereby enabling the state of a battery assembly including a plurality of battery banks to be diagnosed for each battery bank, and improving the accuracy and reliability of the diagnosis result.

[0145] In addition, the present invention diagnoses the state of the battery bank based on the second differential capacity value of a target peak located in a predetermined voltage range among a plurality of peaks of the second differential profile, thereby accurately diagnosing whether battery cells in a battery bank prepared by connecting battery cells in parallel are deteriorated unevenly.

[0146] In addition, the present invention can manage a battery assembly including multiple battery banks by controlling the charging and / or discharging conditions of the battery bank according to the diagnosis results of the battery bank, thereby extending the lifespan of the entire battery assembly and improving safety.

[0147] Furthermore, it goes without saying that embodiments according to the present invention can solve various technical problems other than those mentioned in the present specification, not only in the relevant technical field but also in related technical fields.

[0148] The present invention has been described with reference to specific embodiments. However, those skilled in the art will clearly understand that various modifications can be implemented within the technical scope of the present invention. Therefore, the embodiments disclosed above should be considered illustrative rather than limiting. In other words, the true scope of the present invention is set forth in the claims, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

[0149] [Explanation of symbols]

[0150] 2: Vehicle

[0151] 10: Battery pack

[0152] 100: Battery Diagnostic Device

[0153] 110: Control unit

[0154] 112: Second-order differential profile generation section

[0155] 112: Diagnostic Department

[0156] 116: Diagnosis result notification section

[0157] 118: Battery Management Unit

[0158] 120: Communications Department

[0159] 130: Input section

[0160] 140: Storage

[0161] 150: Output section

Claims

1. A battery diagnosis method for diagnosing a battery assembly including a battery bank formed by connecting a plurality of battery cells in parallel with each other, A second differentiation profile generation step for generating a second differentiation profile representing the relationship between the second differentiation capacity obtained by second differentiating the capacity of the battery bank with respect to the voltage of the battery bank and the voltage of the battery bank; and A battery diagnosis method comprising a diagnosis step of detecting a target peak located in a predetermined voltage range among a plurality of peaks of the second differential profile and diagnosing the state of the battery bank based on the second differential capacity value of the target peak.

2. In paragraph 1, The above second-order differential profile generation step is: A step of repeatedly measuring the voltage value and current value of the battery bank using at least one electrical sensor while the battery bank is being charged or discharged; and A battery diagnosis method, characterized by comprising a step of generating the second differential profile using voltage values and current values measured while the battery bank is being charged or discharged.

3. In paragraph 1, The above second-order differential profile generation step is: A step of generating a profile showing the relationship between the voltage and capacity of the battery bank; A step of generating a first derivative profile by differentiating the above profile with respect to the voltage of the battery bank; and A battery diagnosis method, characterized by comprising a step of generating the second differential profile by differentiating the first differential profile with respect to the voltage of the battery bank.

4. In paragraph 1, The above diagnostic steps are: A battery diagnosis method characterized by comprising a step of comparing the second differential capacity value of the target peak with a predetermined threshold value, and diagnosing the state of the battery bank as abnormal if the second differential capacity value is less than the threshold value.

5. In paragraph 1, The above diagnostic steps are: A battery diagnosis method characterized by including a step of diagnosing the state of the battery bank as an abnormal state in which the plurality of battery cells are unevenly deteriorated when the second differential capacity value of the target peak is smaller than a predetermined threshold value and the number of target peaks located in the predetermined voltage section exceeds a predetermined reference number.

6. In paragraph 1, The above battery assembly, Including multiple battery banks, The above second-order differential profile generation step is: A step of generating a plurality of secondary differential profiles each corresponding to a plurality of battery banks included in the battery assembly, The above diagnostic steps are: A battery diagnosis method, characterized in that it includes a step of diagnosing the state of each of the plurality of battery banks as a normal state or an abnormal state based on the plurality of second-order differential profiles.

7. In paragraph 1, The above diagnostic steps are: Including a step of diagnosing the state of the battery bank as abnormal when the second differential capacity value of the target peak is less than a predetermined threshold value, The above battery diagnosis method is, A battery diagnosis method characterized in that, when the state of the battery bank is diagnosed as abnormal, the method further includes a step of controlling a charger that charges the battery bank to reduce the voltage at the time of completion of charging of the battery bank or reduce the current rate of the current that charges the battery bank.

8. A battery diagnostic device for diagnosing a battery assembly including a battery bank formed by connecting a plurality of battery cells in parallel with each other, A second derivative profile generation unit that generates a second derivative profile representing the relationship between the second derivative capacity obtained by second differentiating the capacity of the battery bank with respect to the voltage of the battery bank and the voltage of the battery bank; and A battery diagnostic device including a diagnostic unit that detects a target peak located in a predetermined voltage range among a plurality of peaks of the second differential profile and diagnoses the state of the battery bank based on the second differential capacity value of the target peak.

9. In paragraph 8, The above diagnostic section, A battery diagnosis device characterized in that it is configured to compare the second differential capacity value of the target peak with a predetermined threshold value, and to diagnose the state of the battery bank as abnormal if the second differential capacity value is less than the threshold value.

10. In paragraph 8, The above diagnostic section, A battery diagnosis device characterized in that, when the second differential capacity value of the target peak is smaller than a predetermined threshold value and the number of target peaks located in the predetermined voltage section exceeds a predetermined reference number, the status of the battery bank is diagnosed as an abnormal state in which the plurality of battery cells are unevenly deteriorated.

11. In paragraph 8, The above battery assembly comprises a plurality of battery banks, The second differential profile generation unit is configured to generate a plurality of second differential profiles each corresponding to a plurality of battery banks included in the battery assembly, A battery diagnostic device characterized in that the diagnostic unit is configured to diagnose the state of each of the plurality of battery banks as a normal state or an abnormal state based on the plurality of second-order differential profiles.

12. In paragraph 8, The above diagnostic unit is configured to diagnose the state of the battery bank as abnormal when the second differential capacity value of the target peak is less than a predetermined threshold value, The battery diagnosis device further comprises a battery management unit configured to control a charger that charges the battery bank to reduce the voltage upon completion of charging of the battery bank or reduce the current rate of the current that charges the battery bank when the state of the battery bank is diagnosed as abnormal.

13. A battery pack comprising a battery diagnostic device according to any one of claims 8 to 12.

14. A vehicle including a battery diagnostic device according to any one of paragraphs 8 to 12.

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