Battery diagnosis apparatus and battery diagnosis method

Abstract

The battery diagnosis apparatus includes: an information acquisition unit for receiving an output signal from each of a plurality of battery cells of a battery pack to which an AC input signal is applied; and a controller that compares each output signal with a reference signal to determine whether correction is required, corrects the output signals if correction is required to generate a correction signal, and determines a state of each of the plurality of battery cells based on a characteristic of the correction signal.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0009736 filed in the Korean Intellectual Property Office on January 25, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0004] Embodiments disclosed herein relate to a battery diagnosis device and a battery diagnosis method. Background Art

[0005] Recently, devices for stably supplying and managing electric power, such as portable devices like smartphones or laptop computers, electric vehicles or electric skateboards, transportation vehicles like electric two-wheeled vehicles, and energy storage systems (ESS) have been widely used, interest in batteries is increasing and battery development is becoming more active.

[0006] As devices using batteries become more common, the size of the battery recycling market, as well as the general battery market, is increasing. To recycle batteries, it is necessary to accurately diagnose the battery's condition to determine whether it can be recycled.

[0007] As one of representative techniques for diagnosing a battery, there is a scheme using electrochemical impedance spectroscopy (EIS), in which a Nyquist plot with EIS measurement data is used to diagnose a battery. Summary of the Invention

[0008] Technical issues

[0009] The embodiments disclosed herein are directed to providing an apparatus and method for diagnosing the status of each battery cell.

[0010] Technical problems of the embodiments disclosed herein are not limited to the above-mentioned technical problems, and other unmentioned technical problems will be clearly understood by those skilled in the art in the technical field to which the present disclosure pertains based on the following description.

[0011] Technical Solution

[0012] According to an embodiment disclosed herein, a battery diagnostic device includes: an information acquisition unit configured to receive an output signal from each of a plurality of battery cells in a battery pack to which an AC input signal is applied; and a controller configured to compare the output signal with a reference signal to determine whether correction is required, generate a corrected signal by correcting the output signal when correction is required, and determine a state of each of the plurality of battery cells based on characteristics of the corrected signal.

[0013] According to one embodiment, the controller can also be configured to: compare the amplitude and phase of the output signal with the amplitude and phase of the reference signal to determine whether correction is required, and when correction is required, generate a corrected signal by correcting the amplitude or phase of the output signal.

[0014] According to one embodiment, the plurality of battery cells may include n battery cells, and the amplitude of the reference signal may correspond to a value obtained by dividing the amplitude of the AC input signal by n, and the phase of the reference signal may correspond to the phase of the AC input signal.

[0015] According to one embodiment, the controller may be further configured to correct the amplitude or phase of the output signal so that the amplitude or phase of the output signal corresponds to the amplitude or phase of the reference signal.

[0016] According to one embodiment, the controller may be further configured to calculate a frequency-specific impedance response of each of the plurality of battery cells based on the corrected signal.

[0017] According to one embodiment, the controller may be further configured to determine a state of each of the plurality of battery cells based on the specific frequency impedance response.

[0018] According to one embodiment, the controller may be further configured to generate a Nyquist plot based on a frequency-specific impedance response of each of the plurality of battery cells.

[0019] According to one embodiment, the controller may be further configured to determine the state of each of the plurality of battery cells by comparing the Nyquist plot with a reference plot.

[0020] According to one embodiment, the controller may be further configured to compare slopes, X-intercepts, or inflection points of the Nyquist plot and the reference plot with each other.

[0021] According to one embodiment, a sum of the amplitudes of the output signals obtained from each of the plurality of battery cells may correspond to the amplitude of the AC input signal applied to a battery pack including the plurality of battery cells.

[0022] According to one embodiment, the information acquiring unit may be connected to each of the battery cells included in the plurality of battery cells.

[0023] According to a battery diagnostic method according to an embodiment disclosed herein, the battery diagnostic method may include the following steps: applying an AC input signal to a plurality of battery cells; receiving an output signal from each of the plurality of battery cells and generating a corrected signal by correcting the output signal; and determining a state of each of the plurality of battery cells based on characteristics of the corrected signal.

[0024] According to one embodiment, the step of generating the corrected signal may include: comparing the amplitude and phase of the output signal with the amplitude and phase of the reference signal to determine whether correction is required, and when correction is required, generating the corrected signal by correcting the amplitude or phase of the output signal.

[0025] According to one embodiment, the plurality of battery cells may include n battery cells, and the amplitude of the reference signal may correspond to a value obtained by dividing the amplitude of the AC input signal by n, and the phase of the reference signal corresponds to the phase of the AC input signal.

[0026] According to one embodiment, the step of generating the corrected signal may comprise correcting the amplitude or phase of the output signal such that the amplitude or phase of the output signal corresponds to the amplitude or phase of the reference signal.

[0027] According to one embodiment, the step of determining the state may include: calculating a frequency-specific impedance response of each of the plurality of battery cells based on the corrected signal; and determining the state of each of the plurality of battery cells based on the frequency-specific impedance response.

[0028] According to one embodiment, a sum of the amplitudes of the output signals obtained from each of the plurality of battery cells may correspond to an amplitude of the AC input signal applied to a battery pack including the plurality of battery cells.

[0029] Beneficial effects

[0030] A battery diagnostic apparatus and a battery diagnostic method according to embodiments disclosed herein may diagnose a state of each of a plurality of battery cells included in a battery pack.

[0031] The battery diagnostic apparatus and the battery diagnostic method according to the embodiments disclosed herein can diagnose the status of a single cell within a battery pack without disassembling the battery pack. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A battery pack according to embodiments disclosed herein is shown.

[0033] Figure 2 is a diagram of a battery diagnostic device according to an embodiment disclosed herein.

[0034] Figure 3 A battery diagnostic device according to another embodiment disclosed herein is shown.

[0035] Figure 4 A correction process is shown when an output signal of a battery cell has a normal waveform according to an embodiment disclosed herein.

[0036] Figure 5 A process of correcting an amplitude error of an output signal of a battery cell according to an embodiment disclosed herein is shown.

[0037] Figure 6 A process of correcting a phase error of an output signal of a battery cell according to an embodiment disclosed herein is shown.

[0038] Figure 7 is a diagram illustrating an operating method of a battery diagnostic device according to an embodiment disclosed herein.

[0039] Figure 8 is a flow chart of a battery diagnosis method according to an embodiment disclosed herein.

[0040] Figure 9 A computing system for executing a battery diagnosis method according to embodiments disclosed herein is shown. DETAILED DESCRIPTION

[0041] Hereinafter, the embodiments disclosed in this document will be described in detail with reference to the exemplary drawings. When adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals even if they are indicated in different drawings. In addition, when describing the embodiments disclosed in this document, if it is determined that a detailed description of a related known configuration or function obstructs understanding of the embodiments disclosed in this document, the detailed description will be omitted.

[0042] In order to describe the components of the embodiments disclosed herein, terms such as first, second, etc. may be used. These terms are only used to distinguish one component from another component and do not limit the component to the nature, order, sequence, etc. of the component. The terms used herein (including technical and scientific terms) have the same meanings as those commonly understood by those skilled in the art, as long as these terms are not defined differently. Generally, terms defined in commonly used dictionaries should be interpreted as having the same meanings as in the context of the relevant technology, and should not be interpreted as having ideal or exaggerated meanings unless they are clearly defined in this application.

[0043] Figure 1 A battery pack according to embodiments disclosed herein is shown.

[0044] refer to Figure 1 , schematically shows a battery control system according to an embodiment disclosed herein, which includes a battery pack 1 and a higher-level controller 2 included in a higher-level system.

[0045] like Figure 1 As shown, the battery pack 1 may include one or more battery cells 11, a switch unit 14 and a battery management system 20, wherein the switch unit 14 is connected in series to the first terminal side and / or the second terminal side of the battery cell 11 to control the flow of charging / discharging current of the battery cell 11, and the battery management system 20 is used to manage to prevent overcharging and overdischarging by monitoring the voltage, current, temperature, etc. of the battery pack 1.

[0046] In this case, the battery pack 1 may include a plurality of battery cells 11, a sensor 12, a switch unit 14, and a battery management system 20. For example, the first terminal may be a positive (+) terminal of the battery cell 11, and the second terminal may be a negative (-) terminal.

[0047] The battery cell 11 may include a plurality of battery cells. The plurality of battery cells may form a battery pack 1, but the present disclosure is not limited thereto. According to one embodiment, the battery cell 11 may be substantially a battery pack 1. According to another embodiment, the battery cell 11 may be a group of a plurality of battery cells, rather than forming a battery pack. The plurality of battery cells included in the battery cell 11 may be connected to each other so as to be driven as a single unit.

[0048] Here, the switch unit 14 as an element for controlling the flow of current for charging or discharging the plurality of battery cells 11 may use, for example, at least one relay, magnetic contactor, or the like according to the specifications of the battery pack 1 .

[0049] The battery management system 20 may include a plurality of terminals as an interface for receiving the measurement values ​​of the various parameters described above, circuits connected to the terminals to process the received values, etc. The battery management system 20 may control the on / off switching of the switching unit 14 (e.g., a relay, a contactor, etc.), and may be connected to the battery cells 11 to monitor the status of each battery cell 11.

[0050] The higher-level controller 2 can send control signals regarding the battery cells 11 to the battery management system 20. Therefore, the battery management system 20 can also be controlled in terms of its operation based on the signals applied from the higher-level controller 2.

[0051] According to an embodiment, the battery management system 20 may include Figure 2 According to another embodiment, the battery management system 20 may be different from Figure 2 The battery diagnostic device 100. That is, Figure 2 The battery diagnostic apparatus 100 may be included in the battery pack 1 and may be configured as another device outside the battery pack 1. Hereinafter, for convenience of description, it is assumed that the battery diagnostic apparatus 100 includes another device outside the battery pack 1.

[0052] The battery diagnostic device 100 may diagnose the status of the plurality of battery cells 11. The battery diagnostic device 100 may be connected to each of the plurality of battery cells 11. That is, the battery diagnostic device 100 may be directly or indirectly connected to a terminal of each of the plurality of battery cells 11.

[0053] Figure 2 is a diagram of a battery diagnostic device according to an embodiment disclosed herein. Figure 3 A battery diagnostic device according to another embodiment disclosed herein is shown. Figure 4 A correction process is shown when an output signal of a battery cell has a normal waveform according to an embodiment disclosed herein. Figure 5 A process of correcting an amplitude error of an output signal of a battery cell according to an embodiment disclosed herein is shown. Figure 6 A process of correcting a phase error of an output signal of a battery cell according to an embodiment disclosed herein is shown. Figure 7 is a diagram illustrating an operating method of a battery diagnostic device according to an embodiment disclosed herein.

[0054] First, refer to Figure 2 The battery diagnosis device 100 may include an information acquisition unit 110 , a storage unit 120 , and a controller 130 .

[0055] The information acquisition unit 110 can measure the voltage of each battery cell 11. To this end, the information acquisition unit 110 can be connected to each individual battery cell included in the plurality of battery cells 11. Specifically, the information acquisition unit 110 can be connected to the first terminal and the second terminal of each battery cell included in the plurality of battery cells 11 to obtain the voltage between the first terminal and the second terminal. Here, the first terminal can be a (+) terminal and the second terminal can be a (-) terminal, but is not limited thereto. The voltage of each battery cell 11 obtained by the information acquisition unit 110 can be defined as an output signal 210.

[0056] The storage unit 120 may store the voltage of each battery cell 11 obtained by the information acquisition unit 110. That is, the storage unit 120 may receive the output signal 210 from the information acquisition unit 110 and store the output signal 210. According to one embodiment, the storage unit 120 may store not only the output signal 210 but also a reference signal 220 used to determine whether to correct the output signal 210 and a correction signal 230 generated by the controller 130. The storage unit 120 may transmit the output signal 210 to the controller 130.

[0057] The controller 130 may control the waveform generator 30. The controller 130 may control the waveform generator 30 to apply an AC input signal to the plurality of battery cells 11. That is, the controller 130 may transmit a command for generating an AC input signal to the waveform generator 30, which may then apply the AC input signal to the plurality of battery cells 11 based on the command received from the controller 130. According to an embodiment, the waveform generator 30 may be configured as a device separate from the battery diagnostic apparatus 100, rather than being included in the battery diagnostic apparatus 100. Therefore, the controller 130 may be connected to the waveform generator 30 to wirelessly transmit a command for generating an AC input signal to the waveform generator 30, or transmit a command for generating an AC input signal by using wireless communication without a separate connection.

[0058] The controller 130 may control the waveform generator 30 to control the frequency of the AC input signal applied to the plurality of battery cells 11. According to one embodiment, the controller 130 may control the waveform generator 30 to gradually increase the frequency of the AC input signal applied to the plurality of battery cells 11. When the controller 130 controls the frequency of the AC input signal, the controller 130 may control the frequency of the output signal 210 obtained by the information acquisition unit 110 from the plurality of battery cells 11.

[0059] The controller 130 may receive the output signal 210 from the information acquisition unit 110. Here, the output signal 210 may be the voltage of each of the plurality of battery cells 11, so that the controller 130 may receive the voltage of each of the plurality of battery cells 11. According to one embodiment, the controller 130 may receive the output signal 210 from the storage unit 120.

[0060] Controller 130 may determine whether correction of output signal 210 is necessary. Specifically, controller 130 may compare output signal 210 with reference signal 220 to determine whether correction of output signal 210 is necessary. Here, controller 130 may determine that correction is not necessary when output signal 210 corresponds to reference signal 220, and may determine that correction of output signal 210 is necessary when output signal 210 does not correspond to reference signal 220. Therefore, when correction of output signal 210 is necessary, controller 130 may correct output signal 210 to generate corrected signal 230. Therefore, when correction of output signal 210 is not necessary, controller 130 may treat output signal 210 as corrected signal 230.

[0061] Reference Figure 3 The battery diagnostic device 100_1 may include an information acquisition unit 110_1, a storage unit 120_1, a controller 130_1, and a waveform generator 140_1. Specifically, according to various embodiments, the battery diagnostic device 100_1 may include the waveform generator 140_1. In this case, the controller 130_1 included in the battery diagnostic device 100_1 may send a command to generate an AC input signal to the waveform generator 140_1 in the same device. To this end, the controller 130_1 may control the waveform generator 140_1.

[0062] The controller 130_1 may control the waveform generator 140_1 to control the frequency of the AC input signal applied to the plurality of battery cells 11. According to an embodiment, the controller 130_1 may control the waveform generator 140_1 to gradually increase the frequency of the AC input signal applied to the plurality of battery cells 11. When the controller 130_1 controls the frequency of the AC input signal, the controller 130_1 may control the frequency of the output signal 210 obtained by the information acquisition unit 110_1 from the plurality of battery cells 11.

[0063] That is, in addition to including the waveform generator 140_1, according to Figure 3 The battery diagnostic device 100_1 of the embodiment can be used with Figure 2 The battery diagnosis device 100 of the embodiment of the present invention is substantially the same. In the following, for the convenience of description, it will be assumed that the battery diagnosis device 100 and the waveform generator 30 are configured as follows Figure 2 The description will be made with reference to the separated devices shown.

[0064] refer to Figure 4 , the controller 130 may receive the output signal 210 from the information acquiring unit 110 .

[0065] The controller 130 may compare the output signal 210 with a reference signal 220. Here, the reference signal 220 may be defined as a preset signal for checking an error in the amplitude or phase of the output signal 210.

[0066] According to one embodiment, the reference signal 220 can be a signal arbitrarily set by the user to check for errors in the amplitude or phase of the output signal 210. For example, the user can define a signal as the reference signal 220, the amplitude of which is a value obtained by dividing the amplitude of the AC input signal by the number of battery cells included in the plurality of battery cells, and the phase of which is the same as the phase of the AC input signal. That is, when the plurality of battery cells 11 include n battery cells, the amplitude of the reference signal 220 can correspond to the value obtained by dividing the amplitude of the AC input signal by n, and the phase of the reference signal 220 can correspond to the phase of the AC input signal. In this case, the sum of the amplitudes of the output signal 210 obtained by the information acquisition unit 110 from each of the plurality of battery cells 11 can correspond to the amplitude of the AC input signal applied to the battery pack including the plurality of battery cells 11.

[0067] To facilitate understanding, it is assumed that the amplitude of the AC input signal is 100, and the plurality of battery cells 11 includes 100 battery cells. In this case, the amplitude of the reference signal 220 may be 1 obtained by dividing the amplitude of the AC input signal 100 by the number of battery cells 100 included in the plurality of battery cells 11, and the phase of the reference signal 220 may be the same as the phase of the AC input signal.

[0068] Furthermore, the controller 130 has been described as configuring the reference signal 220 based on the AC input signal, but is not limited thereto. According to another embodiment, the amplitude and phase of the reference signal 220 may be the amplitude and phase of a preset random signal independent of the amplitude and phase of the AC input signal.

[0069] The controller 130 may compare the amplitude and phase of the output signal 210 with the amplitude and phase of the reference signal 220. For example, when the amplitude of the output signal 210 is the same as that of the reference signal 220 and the phase of the output signal 210 is the same as that of the reference signal 220, the controller 130 may determine that the output signal 210 has a normal waveform. In this case, the controller 130 may determine that there is no need to correct the output signal 210. Therefore, the controller 130 may regard the output signal 210 as a corrected signal 230.

[0070] According to various embodiments, the controller 130 may determine that the output signal 210 has a normal waveform not only when the amplitude and phase of the output signal 210 are identical to those of the reference signal 220, but also when the amplitude and phase of the output signal 210 do not deviate from a preset range of the amplitude and phase of the reference signal 220. In this regard, the controller 130 may set a range for determining that the output signal 210 has a normal waveform in terms of amplitude and phase. That is, the controller 130 may set a range for determining that the output signal 210 has a normal waveform, taking into account the type of battery pack and battery cells, the number of battery cells included in the battery pack, the use of the battery pack, and the like.

[0071] refer to Figure 5 , the controller 130 can correct the amplitude of the output signal 210.

[0072] The controller 130 may receive the output signal 210 from the information acquisition unit 110 and compare the output signal 210 with the reference signal 220. In this case, the controller 130 may compare the amplitude of the output signal 210 with the amplitude of the reference signal 220. According to one embodiment, the controller 130 may calculate the ratio of the amplitude of the output signal 210 to the amplitude of the reference signal 220. When the ratio of the amplitude of the output signal 210 to the amplitude of the reference signal 220 exceeds a preset ratio, the controller 130 may determine that the amplitude of the output signal 210 is abnormal.

[0073] When the amplitude of the output signal 210 is abnormal, the controller 130 may correct the amplitude of the output signal 210. According to one embodiment, the controller 130 may correct the amplitude of the output signal 210 by multiplying the output signal 210 by the inverse of the ratio of the output signal 210 to the reference signal 220, thereby generating a corrected signal 230. Therefore, the amplitude of the corrected signal 230 generated based on the output signal 210 of each battery cell included in the plurality of battery cells 11 may be corrected to be the same as the amplitude of the reference signal 220.

[0074] For ease of description, assume that the amplitude of the reference signal 220 is 1 and the amplitude of the output signal 210 is 0.8. The controller 130 can calculate the ratio of the output signal 210 to the reference signal 220 to obtain 0.8 / 1. In this case, the controller 130 can determine that 0.8 / 1 exceeds the preset ratio and correct the amplitude of the output signal 210 to 1 by multiplying the amplitude of the output signal 210 by 1 / 0.8, thereby generating a corrected signal 230. In this way, the controller 130 can correct the amplitude of the corrected signal 230 of each battery cell included in the plurality of battery cells 11 to 1.

[0075] According to various embodiments, the controller 130 may determine whether the output signal 210 has an amplitude abnormality based on a difference between the amplitude of the output signal 210 and the amplitude of the reference signal 220 .

[0076] refer to Figure 6 , the controller 130 can correct the phase of the output signal 210.

[0077] The controller 130 may receive the output signal 210 from the information acquiring unit 110 and compare the output signal 210 with the reference signal 220. In this case, the controller 130 may compare the phase of the output signal 210 with the phase of the reference signal 220.

[0078] According to an embodiment, when the difference between the phase of the output signal 210 and the phase of the reference signal 220 is outside a preset range, the controller 130 may determine that the phase of the output signal 210 is abnormal.

[0079] When the phase of the output signal 210 is determined to be abnormal, the controller 130 may correct the phase of the output signal 210. According to an embodiment, the controller 130 may generate a corrected signal 230 by correcting the phase of the output signal 210 so that the phase of the output signal 210 corresponds to the phase of the reference signal 220. Therefore, the phase of the corrected signal 230 generated based on the output signal 210 of each battery cell included in the plurality of battery cells 11 may be corrected to be the same as the phase of the reference signal 220.

[0080] The controller 130 can repeat the above correction of the output signal 210 by adjusting the frequency of the AC input signal. In this way, the controller 130 can obtain the corrected signal 230 of various frequencies.

[0081] The controller 130 may calculate a frequency-specific impedance response based on the corrected signal 230 of each of the plurality of battery cells 11. According to one embodiment, the controller 130 may calculate the impedance response using EIS. According to one embodiment, EIS can be understood as a method for generating and interpreting a Nyquist plot 320 based on the result of applying alternating current to a battery.

[0082] More specifically, the controller 130 may identify the impedance response calculated based on the corrected signal 230 of each battery cell included in the plurality of battery cells 11 as the real part Z real and the imaginary part Z imag The controller 130 may generate an impedance profile based on the real and imaginary parts of each impedance response. Thus, an impedance profile may include impedance information generated based on the corrected signal 230 of the battery cell at various frequencies.

[0083] refer to Figure 7 , the controller 130 may generate the Nyquist diagram 320 based on the impedance diagram. That is, the controller 130 may represent the frequency of the AC input signal, the real part of the impedance, and the imaginary part of the impedance as a point based on the impedance diagram on the coordinate plane, wherein the coordinate plane represents the real part Z of the impedance response. real as the X-axis and the imaginary part Z of the impedance response imag Here, the impedance response at a specific frequency can be displayed as a point on the Nyquist diagram 320. In this way, the controller 130 can repeat the same operation at multiple frequencies and connect the multiple points formed in this way to show a graph.

[0084] The controller 130 can determine the state of each of the plurality of battery cells 11 by comparing the Nyquist plot 320 with the reference graph 420. The Nyquist plot 320 generated by the controller 130 can be divided into a second line 321 and a third line 322 relative to the first line 310. Here, the first line 310 can be defined as a line drawn perpendicular to the X-axis from the inflection point of the Nyquist plot 320. The second line 321 can be defined as the Nyquist plot 320 located opposite to the X-axis direction relative to the first line 310. The third line 322 can be defined as the Nyquist plot 320 located in the X-axis direction relative to the first line 310.

[0085] The reference graph 420 configured by the controller 130 may be divided into a fifth line 421 and a sixth line 422 relative to the fourth line 410. Here, the fourth line 410 may be defined as a line drawn perpendicular to the X-axis from the inflection point of the reference graph 420. The fifth line 421 may be defined as the reference graph 420 located in a position opposite to the X-axis direction relative to the fourth line 410. The sixth line 422 may be defined as the reference graph 420 located in the X-axis direction relative to the fourth line 410.

[0086] Hereinafter, the preset range in each case may be set based on the types of the battery pack and the battery cells, the number of battery cells included in the battery pack, the use of the battery pack, and the like.

[0087] Controller 130 may compare the X-intercept of Nyquist plot 320 with the X-intercept of reference plot 420. The X-intercept of Nyquist plot 320 may be defined as first X-intercept 330. Reference plot 420 may be defined as second X-intercept 430. Controller 130 may compare the position of first X-intercept 330 with the position of second X-intercept 430. When the position of first X-intercept 330 deviates from the position of second X-intercept 430 by more than a preset range, controller 130 may determine that the battery cell is defective. First X-intercept 330 and second X-intercept 430 each represent a net real impedance, so in this case, controller 130 may determine that the battery cell has an internal resistance problem.

[0088] The controller 130 may compare the slope of the third line 322 with the slope of the fifth line 421. When the slope of the third line 322 deviates from the slope of the fifth line 421 by more than a preset range, the controller 130 may determine that the battery cell is defective. In this case, the controller 130 may determine that there is a problem with the diffusion effect inside the battery cell.

[0089] In addition, the inflection point of the Nyquist plot 320 may be defined as a first inflection point 340. The inflection point of the reference plot 420 may be defined as a second inflection point 440. The controller 130 may compare the radius of curvature of the second line 321 and the first inflection point 340 with the radius of curvature of the fifth line 421 and the second inflection point 440. When the radius of curvature of the second line 321 or the position of the first inflection point deviates from the radius of curvature of the fifth line 421 or the position of the second inflection point by more than a preset range, the controller 130 may determine that the battery cell is defective. In this case, the controller 130 may determine that there is a problem with charge transfer in the battery cell.

[0090] When Nyquist plot 320 corresponds to reference plot 420, controller 130 may determine that the battery cell is normal. More specifically, when the position of first X-intercept 330 deviates from the position of second intercept 430 within a preset range, the slope of third line 322 deviates from the slope of fifth line 421 within a preset range, and the radius of curvature of second line 321 and the position of first inflection point 340 deviate from the radius of curvature of fifth line 421 and the position of second inflection point 440 within a preset range, controller 130 may determine that the battery cell is normal.

[0091] Figure 8 is a flow chart of a battery diagnosis method according to an embodiment disclosed herein.

[0092] Figure 8 The embodiments shown in the drawings may be examples, and the order of operations according to various embodiments of the present disclosure may be different from Figure 8 The order shown in the Figure 8For some of the operations shown in , the order of the operations may be changed, or the operations may be combined.

[0093] Reference Figure 8 The battery diagnosis method may include an operation S110 of applying an AC input signal to the battery cell 11, an operation S120 of obtaining an output signal 210 from the battery cell 11, an operation S130 of determining whether the output signal 210 needs to be corrected, an operation S140 of treating the output signal 210 as a corrected signal 230, an operation S150 of generating the corrected signal 230, and an operation S160 of determining a state of the battery cell 11 based on characteristics of the corrected signal 230.

[0094] In the following, reference will be made to Figures 1 to 7 Operations S110 to S160 are described in detail.

[0095] In operation S110, the battery diagnostic apparatus 100 may control the waveform generator to apply an AC input signal to the plurality of battery cells 11. That is, the battery diagnostic apparatus 100 may transmit a command for generating the AC input signal to the waveform generator, and the waveform generator may then apply the AC input signal to the plurality of battery cells 11 based on the command received from the battery diagnostic apparatus 100.

[0096] The battery diagnostic apparatus 100 may control the waveform generator 30 to control the frequency of the AC input signal applied to the plurality of battery cells 11. According to an embodiment, the battery diagnostic apparatus 100 may control the waveform generator 30 to gradually increase the frequency of the AC input signal applied to the plurality of battery cells 11.

[0097] After operation S110 , operation S120 may be performed.

[0098] In operation S120, the battery diagnostic device 100 may obtain an output signal 210 from the battery cell 11. To this end, the battery diagnostic device 100 may be connected to each individual battery cell included in the plurality of battery cells 11. Specifically, the battery diagnostic device 100 may be connected to a first terminal and a second terminal of each battery cell included in the plurality of battery cells 11 to obtain a voltage between the first terminal and the second terminal. Here, the first terminal may be a (+) terminal, and the second terminal may be a (-) terminal, but is not limited thereto. The voltage of each battery cell 11 obtained by the battery diagnostic device 100 may be defined as the output signal 210.

[0099] After operation S120 , operation S130 may be performed.

[0100] In operation S130, the battery diagnostic device 100 may determine whether the output signal 210 needs to be corrected. Specifically, the battery diagnostic device 100 may compare the output signal 210 with the reference signal 220 to determine whether the output signal 210 needs to be corrected. Here, the battery diagnostic device 100 may determine that correction is not necessary when the output signal 210 corresponds to the reference signal 220, and may determine that correction is necessary when the output signal 210 does not correspond to the reference signal 220. More specifically, the battery diagnostic device 100 may compare the amplitude and phase of the output signal 210 with those of the reference signal 220. When the amplitude of the output signal 210 is the same as that of the reference signal 220 and the phase of the output signal 210 is the same as that of the reference signal 220, the battery diagnostic device 100 may determine that the output signal 210 has a normal waveform. In this case, the battery diagnostic device 100 may determine that correction of the output signal 210 is not necessary. When the amplitude or phase of the output signal 210 does not correspond to the amplitude or phase of the reference signal 220, the battery diagnostic apparatus 100 may determine that the output signal 210 needs to be corrected. If it is determined that the output signal 210 does not need to be corrected, the battery diagnostic apparatus 100 may perform operation S140. If it is determined that the output signal 210 needs to be corrected, the battery diagnostic apparatus 100 may perform operation S150.

[0101] In operation S140, the battery diagnostic apparatus 100 may regard the output signal 210 as the corrected signal 230. That is, the battery diagnostic apparatus 100 may regard the output signal 210 as the corrected signal 230 in a determination process based on the corrected signal 230 in a subsequent process, and determine the state of the battery cell based on the output signal 210.

[0102] After operation S140 , operation S160 may be performed.

[0103] In operation 150, the battery diagnostic device 100 may generate a corrected signal 230. The battery diagnostic device 100 may correct the amplitude of the output signal 210 to generate the corrected signal 230. To this end, the battery diagnostic device 100 may compare the amplitude of the output signal 210 with the amplitude of the reference signal 220. According to an embodiment, the battery diagnostic device 100 may calculate the ratio of the amplitude of the output signal 210 to the amplitude of the reference signal 220. When the ratio of the amplitude of the output signal 210 to the amplitude of the reference signal 220 calculated by the battery diagnostic device 100 exceeds a preset ratio, the battery diagnostic device 100 may determine that the amplitude of the output signal 210 is abnormal. When the amplitude of the output signal 210 is determined to be abnormal, the battery diagnostic device 100 may correct the amplitude of the output signal 210. According to an embodiment, the battery diagnostic device 100 may correct the amplitude of the output signal 210 by multiplying the output signal 210 by the inverse of the ratio of the output signal 210 to the reference signal 220 to generate the corrected signal 230. Therefore, the amplitude of the corrected signal 230 generated based on the output signal 210 of each battery cell included in the plurality of battery cells 11 may be corrected to be the same as the amplitude of the reference signal 220 .

[0104] The battery diagnostic device 100 can correct the phase of the output signal 210 to generate a corrected signal 230. To this end, when the difference between the phase of the output signal 210 and the phase of the reference signal 220 is outside a preset range, the battery diagnostic device 100 can determine that the phase of the output signal 210 is abnormal. When the phase of the output signal 210 is determined to be abnormal, the battery diagnostic device 100 can correct the phase of the output signal 210. According to an embodiment, the battery diagnostic device 100 can generate the corrected signal 230 by correcting the phase of the output signal 210 so that the phase of the output signal 210 corresponds to the phase of the reference signal 220. Therefore, the phase of the corrected signal 230 generated based on the output signal 210 of each battery cell included in the plurality of battery cells 11 can be corrected to be the same as the phase of the reference signal 220.

[0105] After operation S150 , operation S160 may be performed.

[0106] In operation S160, the battery diagnostic apparatus 100 may determine the state of the battery cell 11 based on the characteristics of the corrected signal 230. The battery diagnostic apparatus 100 may calculate a specific frequency impedance response based on the corrected signal 230 of each of the plurality of battery cells 11. According to an embodiment, the battery diagnostic apparatus 100 may calculate the impedance response by using EIS.

[0107] More specifically, the battery diagnostic apparatus 100 may generate an impedance diagram as the real part Z real and the imaginary part Z imagThe corresponding relationship between the impedance response calculated based on the corrected signal 230 of each battery cell included in the plurality of battery cells 11 indicates. Therefore, one impedance map can include impedance information generated based on the corrected signal 230 of the battery cell according to various frequencies. That is, the battery diagnostic apparatus 100 can form a pair through the correspondence between the frequency of the AC input signal, the real part of the impedance, and the imaginary part of the impedance via the impedance map.

[0108] Reference Figure 7 , the battery diagnostic apparatus 100 may generate a Nyquist diagram 320 based on the impedance diagram. That is, the battery diagnostic apparatus 100 may generate a Nyquist diagram 320 based on the real part Z of the impedance response. real is the X axis and the imaginary part Z of the impedance response imag The impedance diagram on the coordinate plane with the Y-axis represents the frequency of the AC input signal, the real part of the impedance, and the imaginary part of the impedance as a single point. Here, the impedance response at a specific frequency can be displayed as a single point on the Nyquist plot 320. In this way, the battery diagnostic device 100 can repeat the same operation at multiple frequencies and connect the multiple points formed in this manner to form a single graph.

[0109] The battery diagnostic apparatus 100 may determine the state of each of the plurality of battery cells 11 by comparing the Nyquist plot 320 with a reference plot. The Nyquist plot 320 generated by the battery diagnostic apparatus 100 may be divided into a second line 321 and a third line 322 with respect to the first line 310.

[0110] The battery diagnostic device 100 may compare the X-intercept of the second line 321 with the X-intercept of the reference graph. The battery diagnostic device 100 may compare the position of the X-intercept of the second line 321 with the position of the X-intercept of the reference graph. When the position of the X-intercept of the second line 321 deviates from the position of the X-intercept of the reference graph by more than a preset range, the battery diagnostic device 100 may determine that the battery cell is defective. The X-intercept of the Nyquist plot 320 indicates that the impedance is a net real number, so in this case, the battery diagnostic device 100 may determine that the battery cell has an internal resistance problem.

[0111] The battery diagnostic apparatus 100 may compare the slope of the third line 322 with the slope of the portion of the reference graph corresponding to the third line 322. When the slope of the third line 322 deviates from the slope of the portion of the reference graph corresponding to the third line 322 by more than a preset range, the battery diagnostic apparatus 100 may determine that the battery cell is defective. In this case, the battery diagnostic apparatus 100 may determine that there is a problem with the diffusion effect within the battery cell.

[0112] The battery diagnostic device 100 may compare the radius of curvature of the second line 321 and the inflection point of the Nyquist plot 320 with the radius of curvature and the inflection point of the portion corresponding to the second line 321 in the reference graph. When the radius of curvature of the second line 321 or the position of the inflection point of the Nyquist plot 320 deviates from the radius of curvature or the inflection point of the portion corresponding to the second line 321 in the reference graph by more than a preset range, the battery diagnostic device 100 may determine that the battery cell is defective. In this case, the battery diagnostic device 100 may determine that there is a problem with charge transfer within the battery cell.

[0113] When Nyquist plot 320 corresponds to reference plot 420, battery diagnostic apparatus 100 can determine that the battery cell is normal. More specifically, when the position of first X-intercept 330 deviates from the position of second intercept 430 within a preset range, the slope of third line 322 deviates from the slope of fifth line 421 within a preset range, and the radius of curvature of second line 321 and the position of first inflection point 340 deviate from the radius of curvature of fifth line 421 and the position of second inflection point 440 within a preset range, battery diagnostic apparatus 100 can determine that the battery cell is normal.

[0114] Figure 9 A computing system for executing a battery diagnosis method according to embodiments disclosed herein is shown.

[0115] Reference Figure 8 , a computing system 500 according to an embodiment disclosed herein may include an MCU 510 , a memory 520 , an input / output I / F 530 , and a communication I / F 540 .

[0116] The MCU 510 may be a processor that executes various programs (e.g., an SOH calculation program, a cell balance target determination program, etc.) stored in the memory 520, processes various data including the SOC and SOH of the plurality of battery cells 11 through these programs, and executes reference Figures 1 to 7 The above functions of the battery diagnostic device 100 are described.

[0117] The memory 520 may store various programs regarding SOH calculation of the battery cells 11 , cell balance target determination, etc. In addition, the memory 520 may store various data such as SOC data, SOH data, etc. of each battery cell 11 .

[0118] The memory 520 may be provided in multiple forms as needed. The memory 520 may be a volatile memory or a non-volatile memory. For the volatile memory 520, a random access memory (RAM), a dynamic RAM (DRAM), a static RAM (SRAM), or the like may be used. For the non-volatile memory 520, a read-only memory (ROM), a programmable ROM (PROM), an electrically alterable ROM (EAROM), an erasable programm ...

[0119] The input / output I / F 530 may provide an interface for transmitting and receiving data by connecting an input device (not shown) such as a keyboard, a mouse, a touch panel, etc. and an output device such as a display (not shown) to the MCU 510 .

[0120] The communication I / F 540 is a component capable of transmitting and receiving various data to and from a server, and may be various devices capable of supporting wired or wireless communication. For example, a program or various data for calculating the state of health (SOH) or determining a balance target for the battery cells 11 may be transmitted to and received from a separately provided external server via the communication I / F 540.

[0121] In this way, the battery diagnosis method according to the embodiments disclosed herein may be recorded in the memory 520 and executed by the MCU 510 .

[0122] The above description is merely an illustration of the technical idea of ​​the present disclosure, and a person skilled in the art to which the embodiments disclosed herein pertain may make various modifications and changes without departing from the basic features of the embodiments of the present disclosure.

[0123] Therefore, the embodiments disclosed herein are intended to describe rather than limit the technical spirit of the embodiments disclosed herein, and the scope of the technical spirit of the present disclosure is not limited by these embodiments disclosed herein. The protection scope of the technical spirit disclosed herein should be interpreted by the appended claims, and all technical spirits within the same scope should be understood to be included within the scope of the present disclosure.

Claims

1. A battery diagnostic device, comprising: an information acquisition unit configured to receive an output signal from each of the plurality of battery cells of the battery pack to which an AC input signal is applied; as well as a controller configured to compare the output signal with a reference signal to determine whether correction is required, generate a corrected signal by correcting the output signal when correction is required, and determine a state of each of the plurality of battery cells based on characteristics of the corrected signal.

2. The battery diagnostic device according to claim 1, wherein: The controller is further configured to compare the amplitude and phase of the output signal with the amplitude and phase of the reference signal to determine whether correction is required, and when correction is required, generate the corrected signal by correcting the amplitude or phase of the output signal.

3. The battery diagnostic device according to claim 2, wherein: The plurality of battery cells includes n battery cells, and an amplitude of the reference signal corresponds to a value obtained by dividing an amplitude of the AC input signal by n, and a phase of the reference signal corresponds to a phase of the AC input signal.

4. The battery diagnostic device according to claim 3, wherein: The controller is further configured to correct the amplitude or phase of the output signal so that the amplitude or phase of the output signal corresponds to the amplitude or phase of the reference signal.

5. The battery diagnostic device according to claim 1, wherein The controller is further configured to calculate a frequency-specific impedance response for each of the plurality of battery cells based on the corrected signal.

6. The battery diagnostic device according to claim 5, wherein: The controller is further configured to determine a state of each of the plurality of battery cells based on the specific frequency impedance response.

7. The battery diagnostic device according to claim 5, wherein: The controller is further configured to generate a Nyquist plot based on a frequency-specific impedance response of each of the plurality of battery cells.

8. The battery diagnostic device according to claim 7, wherein: The controller is further configured to determine a state of each of the plurality of battery cells by comparing the Nyquist plot to a reference plot.

9. The battery diagnostic device according to claim 8, wherein: The controller is further configured to compare a slope, an X-intercept, or an inflection point of the Nyquist plot and a slope, an X-intercept, or an inflection point of the reference plot with each other.

10. The battery diagnostic device according to claim 1, wherein A sum of the amplitudes of the output signals obtained from each of the plurality of battery cells corresponds to an amplitude of the AC input signal applied to the battery pack including the plurality of battery cells.

11. The battery diagnostic device according to claim 1, wherein: The information acquiring unit is connected to each of the battery cells included in the plurality of battery cells.

12. A battery diagnosis method, comprising the following steps: applying an AC input signal to the plurality of battery cells; receiving an output signal from each of the plurality of battery cells and generating a corrected signal by correcting the output signal; as well as A state of each of the plurality of battery cells is determined based on characteristics of the corrected signal.

13. The battery diagnosis method according to claim 12, wherein: The step of generating the corrected signal includes comparing the amplitude and phase of the output signal with the amplitude and phase of the reference signal to determine whether correction is required, and when correction is required, generating the corrected signal by correcting the amplitude or phase of the output signal.

14. The battery diagnosis method according to claim 13, wherein: The plurality of battery cells includes n battery cells, and an amplitude of the reference signal corresponds to a value obtained by dividing an amplitude of the AC input signal by n, and a phase of the reference signal corresponds to a phase of the AC input signal.

15. The battery diagnosis method according to claim 14, wherein: The step of generating the corrected signal comprises correcting the amplitude or phase of the output signal so that the amplitude or phase of the output signal corresponds to the amplitude or phase of the reference signal.

16. The battery diagnosis method according to claim 12, wherein: The steps of determining the status include: calculating a frequency-specific impedance response for each of the plurality of battery cells based on the corrected signal; and A state of each of the plurality of battery cells is determined based on the frequency-specific impedance response.

17. The battery diagnosis method according to claim 12, wherein: A sum of the amplitudes of the output signals obtained from each of the plurality of battery cells corresponds to an amplitude of the AC input signal applied to a battery pack including the plurality of battery cells.

Images