Battery inspection apparatus and battery inspection method

Abstract

The battery diagnostic device includes: an information acquisition unit that receives output signals 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 the output signals with a reference signal to determine whether correction is necessary, corrects the output signals to generate a correction signal if correction is necessary, and determines the state of each of the plurality of battery cells based on the characteristics of the correction signal.

Description

Technology Field

[0001] The embodiments disclosed in this document relate to a battery diagnostic device and a battery diagnostic method. Background Technology

[0002] Recently, as portable devices such as smartphones and laptop computers, means of transportation such as electric vehicles, electric scooters, and electric motorcycles, and devices for stably supplying and managing power such as Energy Storage Systems (ESS) are widely used, interest in batteries is increasing and development is becoming more active.

[0003] With the proliferation of battery-powered devices, the market size for battery recycling and related sectors is growing, in addition to the general battery market. For battery recycling, it is necessary to accurately diagnose the condition of the battery to determine if it is recyclable.

[0004] One of the representative technologies for diagnosing batteries is the method using Electrochemical Impedance Spectroscopy (EIS), which diagnoses batteries using Nyquist plots of EIS measurement data. The problem to be solved

[0005] One objective of the embodiments disclosed in this document is to provide an apparatus and a diagnostic method for diagnosing the condition of each battery cell.

[0006] The technical problems of the embodiments described in this document are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by a person skilled in the art to which the present invention pertains from the description below. means of solving the problem

[0007] A battery diagnostic device according to one embodiment disclosed in this document includes: an information acquisition unit that receives output signals from each of a plurality of battery cells of a battery pack to which an AC input signal is applied; and a controller that determines whether correction is necessary by comparing the output signals with a reference signal, and if correction is necessary, corrects the output signals to generate a correction signal, and determines the state of each of the plurality of battery cells based on the characteristics of the correction signal.

[0008] According to one embodiment, the controller can determine whether correction is necessary by comparing the amplitude and phase of the output signal with the amplitude and phase of a reference signal, respectively, and if correction is necessary, it can generate a correction signal by correcting the amplitude or phase of the output signal.

[0009] According to one embodiment, the plurality of battery cells includes n battery cells, the amplitude of the reference signal corresponds 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.

[0010] According to one embodiment, the controller can correct the amplitude or phase of the output signal to correspond to the amplitude or phase of the reference signal.

[0011] According to one embodiment, the controller can calculate the frequency-dependent impedance response of each of the plurality of battery cells based on the correction signal.

[0012] According to one embodiment, the controller can determine the state of each of the plurality of battery cells based on the frequency-dependent impedance response.

[0013] According to one embodiment, the controller can generate a Nyquist plot based on the frequency-dependent impedance response of each of the plurality of battery cells.

[0014] According to one embodiment, the controller can determine the state of each of the plurality of battery cells by comparing the Nyquist plot and the reference plot.

[0015] According to one embodiment, the controller can compare the slope, X-intercept, or inflection point of the Nyquist plot and the reference plot, respectively.

[0016] According to one embodiment, the sum of the amplitudes of the output signals obtained from each of the plurality of battery cells may correspond to the amplitude of the alternating current input signal applied to a battery pack including the plurality of battery cells.

[0017] According to one embodiment, the information acquisition unit may be connected to each of the battery cells included in the plurality of battery cells.

[0018] A battery diagnostic method according to one embodiment disclosed in this document includes the steps of: applying an AC input signal to a plurality of battery cells; receiving an output signal from each of the plurality of battery cells and correcting the output signal to generate a correction signal; and determining the state of each of the plurality of battery cells based on the characteristics of the correction signal.

[0019] According to one embodiment, the step of generating the correction signal may determine whether correction is necessary by comparing the amplitude and phase of the output signal with the amplitude and phase of the reference signal, respectively, and generate the correction signal if correction is necessary.

[0020] According to one embodiment, the plurality of battery cells includes n battery cells, the amplitude of the reference signal corresponds 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.

[0021] According to one embodiment, the step of generating the correction signal may include the step of correcting the amplitude or phase of the output signal to correspond to the amplitude or phase of the reference signal.

[0022] According to one embodiment, the step of determining the state may be to calculate the frequency-dependent impedance response of each of the plurality of battery cells based on the correction signal, and to determine the state of each of the plurality of battery cells based on the frequency-dependent impedance response.

[0023] According to one embodiment, the sum of the amplitudes of the output signals obtained from each of the plurality of battery cells may correspond to the amplitude of the alternating current input signal applied to a battery pack including the plurality of battery cells. Effects of the invention

[0024] According to the battery diagnostic device and battery diagnostic method according to the embodiments disclosed in this document, the state of each of the plurality of battery cells included in a battery pack can be diagnosed.

[0025] According to the battery diagnostic device and battery diagnostic method according to the embodiments disclosed in this document, the condition of individual cells inside a battery pack can be diagnosed without disassembling the battery pack. Brief explanation of the drawing

[0026] FIG. 1 is a drawing showing a battery pack according to one embodiment disclosed in this document. FIG. 2 is a drawing showing a battery diagnostic device according to one embodiment disclosed in this document. FIG. 3 is a drawing showing a battery diagnostic device according to another embodiment disclosed in this document. FIG. 4 is a diagram showing a correction process when the output signal of a battery cell according to one embodiment disclosed in this document is a normal waveform. FIG. 5 is a diagram showing the process of correcting the amplitude error of the output signal of a battery cell according to one embodiment disclosed in this document. FIG. 6 is a diagram showing the process of correcting the phase error of an output signal of a battery cell according to one embodiment disclosed in this document. FIG. 7 is a drawing showing a diagnostic method of a battery diagnostic device according to one embodiment disclosed in this document. FIG. 8 is a flowchart showing a battery diagnostic method according to one embodiment disclosed in this document. FIG. 9 shows a computing system that executes a battery diagnostic method according to one embodiment disclosed in this document. Specific details for implementing the invention

[0027] The embodiments disclosed in this document are described in detail below with reference to exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the embodiments disclosed in this document, detailed descriptions of related known configurations or functions are omitted if it is determined that such detailed descriptions would hinder understanding of the embodiments disclosed in this document.

[0028] In describing the components of the embodiments disclosed in this document, terms such as "first," "second," etc., may be used. These terms are intended merely to distinguish the components from other components and do not limit the essence, order, or sequence of the components. Furthermore, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the embodiments disclosed in this document pertain. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0029] FIG. 1 is a drawing showing a battery pack according to one embodiment disclosed in this document.

[0030] Referring to FIG. 1, a battery control system including a battery pack (1) and a higher controller (2) included in a higher system according to one embodiment disclosed in this document is schematically shown.

[0031] As illustrated in FIG. 1, the battery pack (1) may include one or more battery cells (11), a switching unit (14) connected in series to the first terminal side and / or second terminal side of the battery cells (11) to control the flow of charging and discharging current of the battery cells (11), and a battery management system (20) that monitors the voltage, current, temperature, etc. of the battery pack (1) to prevent overcharging and over-discharging.

[0032] In this case, the battery pack (1) may be equipped with a plurality of battery cells (11), a sensor (12), a switching unit (14), and a battery management system (20). For example, the first terminal may be the (+) terminal of the battery cells (11), and the second terminal may be the (-) terminal.

[0033] The battery cells (11) may include a plurality of battery cells. The plurality of battery cells may form a single battery pack (1), but are not limited thereto. According to an embodiment, the battery cells (11) may be a single battery pack (1). According to another embodiment, the battery cells (11) may not form a pack and may be a collection of a plurality of battery cells. The plurality of battery cells included in the battery cells (11) may be connected to each other and operated as a single unit.

[0034] Here, the switching unit (14) is a device for controlling the current flow for charging or discharging a plurality of battery cells (11), and, for example, depending on the specifications of the battery pack (1), at least one relay, magnetic contactor, etc. may be used.

[0035] The battery management system (20) is an interface that receives values ​​of various parameters measured above, and may include a plurality of terminals and a circuit connected to these terminals to perform processing of the received values. Additionally, the battery management system (20) may control the ON / OFF of a switching unit (14), such as a relay or contactor, and may be connected to battery cells (11) to monitor the status of each of the battery cells (11).

[0036] The upper controller (2) can transmit control signals for the battery cells (11) to the battery management system (20). Accordingly, the operation of the battery management system (20) can be controlled based on the signals applied from the upper controller (2).

[0037] According to an embodiment, the battery management system (20) may include the battery diagnostic device (100) of FIG. 2. According to another embodiment, the battery management system (20) may be a different system from the battery diagnostic device (100) of FIG. 2. That is, the battery diagnostic device (100) of FIG. 2 may be included in the battery pack (1) or may be composed of another device outside the battery pack (1). For convenience of explanation, the following description assumes that the battery diagnostic device (100) is composed of another device outside the battery pack (1).

[0038] The battery diagnostic device (100) can diagnose the condition of a plurality of battery cells (11). Additionally, the battery diagnostic device (100) can be connected to each of the battery cells included in the plurality of battery cells (11). That is, the battery diagnostic device (100) can be connected directly or indirectly to each of the terminals of the battery cells included in the plurality of battery cells (11).

[0039] FIG. 2 is a drawing showing a battery diagnostic device according to one embodiment disclosed in this document. FIG. 3 is a drawing showing a battery diagnostic device according to another embodiment disclosed in this document. FIG. 4 is a drawing showing a correction process when the output signal of a battery cell is a normal waveform according to one embodiment disclosed in this document. FIG. 5 is a drawing showing a correction process for an amplitude error of the output signal of a battery cell according to one embodiment disclosed in this document. FIG. 6 is a drawing showing a correction process for a phase error of the output signal of a battery cell according to one embodiment disclosed in this document. FIG. 7 is a drawing showing a diagnostic method of a battery diagnostic device according to one embodiment disclosed in this document.

[0040] First, referring to FIG. 2, the battery diagnostic device (100) may include an information acquisition unit (110), a storage unit (120), and a controller (130).

[0041] The information acquisition unit (110) can measure the voltage of each of the battery cells (11). To this end, the information acquisition unit (110) can be connected to each individual battery cell included in each of the plurality of battery cells (11). That is, the information acquisition unit (110) can be connected to the first terminal and the second terminal of each of the battery cells included in the plurality of battery cells (11) to acquire the 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 of the battery cells (11) acquired by the information acquisition unit (110) can be defined as an output signal (210).

[0042] The storage unit (120) can store the voltage of each of the battery cells (11) acquired by the information acquisition unit (110). That is, the storage unit (120) can receive the output signal (210) from the information acquisition unit (110) and store the output signal (210). According to an embodiment, the storage unit (120) may store not only the output signal (210), but also a reference signal (220) for determining whether the output signal (210) needs correction, and a correction signal (230) generated by the controller (130). Meanwhile, the storage unit (120) can transmit the output signal (210) to the controller (130).

[0043] The controller (130) can control the waveform generator (30). The controller (130) can control the waveform generator (30) to apply an AC input signal to a plurality of battery cells (11). That is, the controller (130) can transmit a command to the waveform generator (30) to generate an AC input signal, and the waveform generator (30) can apply an AC input signal to a plurality of battery cells (11) based on the command received from the controller (130). According to an embodiment, the waveform generator (30) may not be included in the battery diagnostic device (100) and may be configured as a separate device from the battery diagnostic device (100). Accordingly, the controller (130) may be connected to the waveform generator (30) and transmit a command to generate an AC input signal to the waveform generator (30) via a wired connection, or it may transmit a command to generate an AC input signal using wireless communication without a separate connection.

[0044] The controller (130) can control the frequency of the AC input signal applied to the plurality of battery cells (11) by controlling the waveform generator (30). According to an embodiment, the controller (130) can gradually increase the frequency of the AC input signal applied to the plurality of battery cells (11) by controlling the waveform generator (30). By controlling the frequency of the AC input signal, the controller (130) can control the frequency of the output signal (210) obtained by the information acquisition unit (110) from the plurality of battery cells (11).

[0045] The controller (130) can receive an output signal (210) from the information acquisition unit (110). Here, the output signal (210) may be the voltage of each battery cell included in the plurality of battery cells (11), and accordingly, the controller (130) can receive the voltage of each battery cell included in the plurality of battery cells (11). According to an embodiment, the controller (130) may also receive an output signal (210) from the storage unit (120).

[0046] The controller (130) can determine whether the output signal (210) requires correction. That is, the controller (130) can determine whether the output signal (210) requires correction by comparing the output signal (210) with the reference signal (220). Here, the controller (130) can determine that no correction is required if the output signal (210) corresponds to the reference signal (220), and determine that the output signal (210) requires correction if the output signal (210) does not correspond to the reference signal (220). Accordingly, if the output signal (210) requires correction, the controller (130) can correct the output signal (210) to generate a correction signal (230). Additionally, if the output signal (210) does not require correction, the controller (130) can consider the output signal (210) as a correction signal (230).

[0047] Referring to FIG. 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). That is, according to various embodiments, the battery diagnostic device (100_1) may include a waveform generator (140_1). In this case, the controller (130_1) included in the battery diagnostic device (100_1) may transmit a command to the waveform generator (140_1) to generate an AC input signal within the same device. Through this, the controller (130_1) can control the waveform generator (140_1).

[0048] The controller (130_1) can control the frequency of the AC input signal applied to the plurality of battery cells (11) by controlling the waveform generator (140_1). According to an embodiment, the controller (130_1) can gradually increase the frequency of the AC input signal applied to the plurality of battery cells (11) by controlling the waveform generator (140_1). By controlling the frequency of the AC input signal, the controller (130_1) can control the frequency of the output signal (210) obtained by the information acquisition unit (110_1) from the plurality of battery cells (11).

[0049] That is, the battery diagnostic device (100_1) according to the embodiment of FIG. 3 may be substantially identical to the battery diagnostic device (100) according to the embodiment of FIG. 2, except that it includes a waveform generator (140_1). For convenience of explanation, the following description assumes that the battery diagnostic device (100) and the waveform generator (30) are configured as separate devices as in FIG. 2.

[0050] Referring to FIG. 4, the controller (130) can receive an output signal (210) from the information acquisition unit (110).

[0051] The controller (130) can compare the output signal (210) with the reference signal (220). Here, the reference signal (220) may be defined as a pre-set signal to check the amplitude or phase error of the output signal (210).

[0052] According to an embodiment, the reference signal (220) may be a signal arbitrarily set by the user to check for an error in the amplitude or phase of the output signal (210). For example, the user may define the reference signal (220) as a signal in which the amplitude is the 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 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) corresponds to the value obtained by dividing the amplitude of the AC input signal by n, and the phase of the reference signal (220) corresponds to the phase of the AC input signal. In this case, the sum of the amplitudes of the output signals (210) obtained by the information acquisition unit (110) from each of the plurality of battery cells (11) may correspond to the amplitude of the AC input signal applied to the battery pack including the plurality of battery cells (11).

[0053] For the sake of understanding, it is assumed that the amplitude of the AC input signal is 100 and that the plurality of battery cells (11) includes 100 battery cells. In this case, the amplitude of the reference signal (220) is 1, which is the amplitude of the AC input signal 100 divided by the number of battery cells included in the plurality of battery cells (11), which is 100, and the phase of the reference signal (220) may be the same as the phase of the AC input signal.

[0054] Meanwhile, although the description is based on the premise that the controller (130) sets the reference signal (220) based on the AC input signal, it is not limited thereto. According to another embodiment, the amplitude and phase of the reference signal (220) may be the amplitude and phase of any signal that is pre-set independently of the amplitude and phase of the AC input signal.

[0055] The controller (130) can compare the amplitude and phase of the output signal (210) with the amplitude and phase of the reference signal (220), respectively. For example, the controller (130) can determine that the output signal (210) is a normal waveform if the amplitude of the output signal (210) and the amplitude of the reference signal (220) are the same, and the phase of the output signal (210) and the phase of the reference signal (220) are the same. In this case, the controller (130) can determine that no correction is required for the output signal (210). Accordingly, the controller (130) can regard the output signal (210) itself as a correction signal (230).

[0056] According to various embodiments, the controller (130) may determine that the output signal (210) is a normal waveform not only when the amplitude and phase of the output signal (210) are the same as the amplitude and phase of the reference signal (220), but also when the amplitude and phase of the output signal (210) do not exceed a preset range when compared to the amplitude and phase of the reference signal (220). In this regard, the controller (130) may set a range for determining the output signal (210) as a normal waveform in relation to the amplitude and phase. That is, the controller (130) may set a range for determining the output signal (210) as a normal waveform by considering the type of battery pack and battery cell, the number of battery cells included in the battery pack, and the intended use of the battery pack.

[0057] Referring to FIG. 5, the controller (130) can correct the amplitude of the output signal (210).

[0058] The controller (130) receives an output signal (210) from the information acquisition unit (110) and can compare the output signal (210) with a reference signal (220). At this time, the controller (130) can compare the amplitude of the output signal (210) with the amplitude of the reference signal (220). According to an embodiment, the controller (130) can calculate the ratio of the amplitude of the output signal (210) to the amplitude of the reference signal (220). If the ratio of the amplitude of the output signal (210) to the amplitude of the reference signal (220) calculated by the controller (130) exceeds a preset ratio, the controller (130) can determine that the output signal (210) is above the amplitude.

[0059] If the output signal (210) is determined to be above a certain amplitude, the controller (130) can correct the amplitude of the output signal (210). According to an embodiment, the controller (130) can generate a corrected signal (230) by correcting the amplitude of the output signal (210) by multiplying the output signal (210) by the reciprocal of the ratio of the output signal (210) to the reference signal (220). Accordingly, the amplitude of the corrected signal (230) generated by the controller (130) based on the output signal (210) of each battery cell included in the plurality of battery cells (11) can all be corrected to be equal to the amplitude of the reference signal (220).

[0060] For convenience of explanation, it is assumed 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) and derive 0.8 / 1. In this case, the controller (130) determines that 0.8 / 1 exceeds a preset ratio and can generate a correction signal (230) by multiplying the amplitude of the output signal (210) by 1 / 0.8 to correct the amplitude of the output signal (210) to 1. Through this, the controller (130) can correct the amplitude of each correction signal (230) of the battery cells included in the plurality of battery cells (11) to 1.

[0061] Meanwhile, according to various embodiments, the controller (130) may determine whether the amplitude of the output signal (210) is abnormal based on the difference between the amplitude of the output signal (210) and the amplitude of the reference signal (220).

[0062] Referring to FIG. 6, the controller (130) can correct the phase of the output signal (210).

[0063] The controller (130) receives an output signal (210) from the information acquisition unit (110) and can compare the output signal (210) with the reference signal (220). At this time, the controller (130) can compare the phase of the output signal (210) with the phase of the reference signal (220).

[0064] 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 when the controller (130) compares the phase of the output signal (210) with the phase of the reference signal (220), the controller (130) can determine that the output signal (210) is out of phase.

[0065] If the output signal (210) is determined to be out of phase, the controller (130) can correct the phase of the output signal (210). According to an embodiment, the controller (130) can generate a correction 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). Accordingly, the phase of the correction signal (230) generated by the controller (130) based on the output signal (210) of each battery cell included in the plurality of battery cells (11) can all be corrected to be the same as the phase of the reference signal (220).

[0066] The controller (130) can adjust the frequency of the AC input signal and repeatedly perform correction of the output signal (210) described above. Through this, the controller (130) can obtain correction signals (230) of various frequencies.

[0067] The controller (130) can calculate a frequency-dependent impedance response based on a correction signal (230) of each battery cell included in a plurality of battery cells (11). According to an embodiment, the controller (130) can calculate the impedance response using electrochemical impedance spectroscopy (EIS). According to an embodiment, electrochemical impedance spectroscopy can be understood as a method of generating and interpreting a Nyquist diagram (320) based on the result of applying an AC power source to the battery.

[0068] Specifically, the controller (130) calculates the impedance response based on the correction signal (230) of each battery cell included in the plurality of battery cells (11), and the real part (Z real ) and imaginary part (Z imag It can be distinguished as ). And, the controller (130) can generate an impedance profile based on the real and imaginary parts of each impedance response. Accordingly, one impedance profile may include impedance information generated based on the correction signal (230) of the battery cell according to various frequencies.

[0069] Referring to FIG. 7, the controller (130) can generate a Nyquist plot (320) based on an impedance profile. That is, the controller (130) has the X-axis as the real part (Z) of the impedance response. real ), the Y-axis is the imaginary part of the impedance response (Z imagBased on the impedance profile on a coordinate plane, the frequency of the AC input signal, the real part of the impedance, and the imaginary part of the impedance can be represented as a single point. Here, the impedance response at a specific frequency can be plotted as a single point on the Nyquist plot (320). In this way, the controller (130) can repeat the same operation for multiple frequencies and plot a single graph by connecting multiple points formed through this.

[0070] The controller (130) can determine the state of each of the multiple battery cells (11) by comparing the Nyquist plot (320) with the reference plot (420). The Nyquist plot (320) generated by the controller (130) can be divided into a second line (321) and a third line (322) based on a first line (310). Here, the first line (310) can be defined as a line drawn perpendicular to the X-axis at the inflection point of the Nyquist plot (320). The second line (321) can be defined as a Nyquist plot (320) located in a direction opposite to the X-axis direction based on the first line (310). The third line (322) can be defined as a Nyquist plot (320) located in the X-axis direction based on the first line (310).

[0071] The reference line (420) set by the controller (130) can be divided into a fifth line (421) and a sixth line (422) based on the fourth line (410). Here, the fourth line (410) can be defined as a line drawn perpendicular to the X-axis at the inflection point of the reference line (420). The fifth line (421) can be defined as a reference line (420) located in a direction opposite to the X-axis direction based on the fourth line (410). The sixth line (422) can be defined as a reference line (420) located in the X-axis direction based on the fourth line (410).

[0072] In the following cases, the pre-set range for each case may be set by considering the type of battery pack and battery cell, the number of battery cells included in the battery pack, and the intended use of the battery pack.

[0073] The controller (130) can compare the X-intercept of the Nyquist plot (320) with the X-intercept of the reference plot (420). The X-intercept of the Nyquist plot (320) can be defined as the first X-intercept (330). The reference plot (420) can be defined as the second X-intercept (430). The controller (130) can compare the position of the first X-intercept (330) with the position of the second X-intercept (430). The controller (130) can determine that the battery cell is defective if the position of the first X-intercept (330) deviates by more than a preset range from the position of the second X-intercept (430). Since the first X-intercept (330) and the second X-intercept (430) each represent cases where the impedance is purely real, in this case, the controller (130) can determine that the battery cell has a problem with its internal resistance.

[0074] The controller (130) can compare the slope of the third line (322) with the slope of the fifth line (421). The controller (130) can determine that the battery cell is defective if the slope of the third line (322) deviates from a preset range in the slope of the fifth line (421). In this case, the controller (130) can determine that there is a problem with the diffusion effect inside the battery cell.

[0075] Meanwhile, the inflection point of the Nyquist plot (320) can be defined as the first inflection point (340). The inflection point of the reference plot (420) can be defined as the second inflection point (440). The controller (130) can compare the radius of curvature and the first inflection point (340) of the second line (321) with the radius of curvature and the second inflection point of the fifth line (421). The controller (130) can determine that the battery cell is defective if the location of the radius of curvature of the second line (321) or the first inflection point deviates by more than a preset range from the radius of curvature of the fifth line (421) or the second inflection point. In this case, the controller (130) can determine that the battery cell has a problem with charge transfer.

[0076] The controller (130) can determine that the battery cell is normal if the Nyquist plot (320) corresponds to the reference plot (420). Specifically, the controller (130) can determine that the battery cell is normal if the position of the first X-intercept (330) does not exceed a preset range from the position of the second X-intercept (430), the slope of the third line (322) does not exceed a preset range from the slope of the fifth line (421), and the radius of curvature of the second line (321) and the position of the first inflection point (340) do not exceed a preset range from the radius of curvature of the fifth line (421) and the position of the second inflection point (440).

[0077] FIG. 8 is a flowchart showing a battery diagnostic method according to one embodiment disclosed in this document.

[0078] The embodiment illustrated in FIG. 8 is merely one embodiment, and the order of operations according to various embodiments of the present invention may differ from that illustrated in FIG. 8, and some steps illustrated in FIG. 8 may be omitted, the order of steps may be changed, or steps may be merged.

[0079] Referring to FIG. 8, the battery diagnostic method may include an operation of applying an AC input signal to battery cells (11) (S110), an operation of obtaining an output signal (210) from battery cells (11) (S120), an operation of determining whether correction of the output signal (210) is required (S130), an operation of considering the output signal (210) as a correction signal (230) (S140), an operation of generating a correction signal (230) (S150), and an operation of determining the state of the battery cells (11) based on the characteristics of the correction signal (230) (S160).

[0080] The above operations S110 to S160 will be explained in detail below with reference to FIGS. 1 to 7.

[0081] In operation S110, the battery diagnostic device (100) can control a waveform generator to apply an AC input signal to a plurality of battery cells (11). That is, the battery diagnostic device (100) can transmit a command to the waveform generator to generate an AC input signal, and the waveform generator can apply an AC input signal to a plurality of battery cells (11) based on the command received from the battery diagnostic device (100).

[0082] The battery diagnostic device (100) can control the frequency of an AC input signal applied to a plurality of battery cells (11) by controlling a waveform generator. According to an embodiment, the battery diagnostic device (100) can gradually increase the frequency of an AC input signal applied to a plurality of battery cells (11) by controlling a waveform generator.

[0083] After operation S110, operation S120 can be performed.

[0084] In operation S120, the battery diagnostic device (100) can obtain an output signal (210) from the battery cells (11). To do this, the battery diagnostic device (100) can be connected to each individual battery cell included in each of the plurality of battery cells (11). That is, the battery diagnostic device (100) can be connected to the first terminal and the second terminal of each of the battery cells included in the plurality of battery cells (11) to obtain the 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 of the battery cells (11) obtained by the battery diagnostic device (100) can be defined as the output signal (210).

[0085] After operation S120, operation S130 can be performed.

[0086] In operation S130, the battery diagnostic device (100) can determine whether correction of the output signal (210) is required. That is, the battery diagnostic device (100) can determine whether correction of the output signal (210) is required by comparing the output signal (210) with the reference signal (220). Here, the battery diagnostic device (100) can determine that correction is not required if the output signal (210) corresponds to the reference signal (220), and determine that correction of the output signal (210) is required if the output signal (210) does not correspond to the reference signal (220). More specifically, the battery diagnostic device (100) can compare the amplitude and phase of the output signal (210) with the amplitude and phase of the reference signal (220). The battery diagnostic device (100) may determine that the output signal (210) is a normal waveform if the amplitude of the output signal (210) and the amplitude of the reference signal (220) are the same, and the phase of the output signal (210) and the phase of the reference signal (220) are the same. In this case, the battery diagnostic device (100) may determine that no correction is required for the output signal (210). Additionally, the battery diagnostic device (100) may determine that correction is required for the output signal (210) if the amplitude or phase of the output signal (210) and the amplitude or phase of the reference signal (220) do not correspond. If the battery diagnostic device (100) determines that no correction is required for the output signal (210), operation S140 may be performed. If the battery diagnostic device (100) determines that correction is required for the output signal (210), operation S150 may be performed.

[0087] In operation S140, the battery diagnostic device (100) may regard the output signal (210) as a correction signal (230). That is, the battery diagnostic device (100) regards the output signal (210) as a correction signal (230), and in the subsequent process of determining based on the correction signal (230), regards the output signal (210) itself as a correction signal (230) and can determine the state of the battery cell based on the output signal (210).

[0088] After operation S140, operation S160 can be performed.

[0089] In operation S150, the battery diagnostic device (100) can generate a correction signal (230). The battery diagnostic device (100) can generate the correction signal (230) by correcting the amplitude of the output signal (210). To do this, the battery diagnostic device (100) can 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) can calculate the ratio of the amplitude of the output signal (210) to the amplitude of the reference signal (220). If 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) can determine that the output signal (210) is above the amplitude. If the output signal (210) is determined to be above the amplitude, the battery diagnostic device (100) can correct the amplitude of the output signal (210). According to an embodiment, the battery diagnostic device (100) can generate a corrected signal (230) by correcting the amplitude of the output signal (210) by multiplying the output signal (210) by the reciprocal of the ratio of the output signal (210) to the reference signal (220). Accordingly, the amplitude of the corrected signal (230) generated by the battery diagnostic device (100) based on the output signal (210) of each battery cell included in the plurality of battery cells (11) can all be corrected to be equal to the amplitude of the reference signal (220).

[0090] Additionally, the battery diagnostic device (100) can generate a correction signal (230) by correcting the phase of the output signal (210). To this end, the battery diagnostic device (100) compares the phase of the output signal (210) with the phase of the reference signal (220). If the difference between the phase of the output signal (210) and the phase of the reference signal (220) exceeds a preset range, the battery diagnostic device (100) can determine that the output signal (210) is phase abnormal. If the output signal (210) is determined to be phase 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 a correction 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). Accordingly, the phase of the correction signal (230) generated by the battery diagnostic device (100) based on the output signal (210) of each battery cell included in the plurality of battery cells (11) can all be corrected to be the same as the phase of the reference signal (220).

[0091] After operation S150, operation S160 can be performed.

[0092] In operation S160, the battery diagnostic device (100) can determine the state of the battery cells (11) based on the characteristics of the correction signal (230). The battery diagnostic device (100) can calculate the frequency-dependent impedance response based on the correction signal (230) of each battery cell included in the plurality of battery cells (11). According to an embodiment, the battery diagnostic device (100) can calculate the impedance response using electrochemical impedance spectroscopy (EIS).

[0093] Specifically, the battery diagnostic device (100) calculates an impedance response based on a correction signal (230) of each battery cell included in a plurality of battery cells (11), and the real part (Z real ) and imaginary part (Z imag An impedance profile can be generated that represents the correspondence between the impedances. Accordingly, one impedance profile may include impedance information generated based on the correction signal (230) of the battery cell according to various frequencies. That is, the battery diagnostic device (100) can form pairs through the impedance profile, such that the frequency of the AC input signal, the real part of the impedance, and the imaginary part of the impedance correspond to each other.

[0094] Referring to FIG. 7, the battery diagnostic device (100) can generate a Nyquist plot (320) based on an impedance profile. That is, the battery diagnostic device (100) has the X-axis as the real part (Z) of the impedance response. real ), the Y-axis is the imaginary part of the impedance response (Z imag Based on the impedance profile on a coordinate plane, the frequency of the AC input signal, the real part of the impedance, and the imaginary part of the impedance can be represented as a single point. Here, the impedance response at a specific frequency can be plotted as a single point on the Nyquist plot (320). In this way, the battery diagnostic device (100) can repeat the same operation for multiple frequencies and plot a single graph by connecting multiple points formed through this.

[0095] The battery diagnostic device (100) can determine the status of each of the multiple battery cells (11) by comparing the Nyquist plot (320) with a reference plot. The Nyquist plot (320) generated by the battery diagnostic device (100) can be divided into a second line (321) and a third line (322) based on a first line (310).

[0096] The battery diagnostic device (100) can compare the X-intercept of the second line (321) with the X-intercept of the reference curve. The battery diagnostic device (100) can compare the position of the X-intercept of the second line (321) with the position of the X-intercept of the reference curve. The battery diagnostic device (100) can determine that the battery cell is defective if the position of the X-intercept of the second line (321) deviates by more than a preset range from the position of the X-intercept of the reference curve. Since the X-intercept of the Nyquist curve (320) signifies the case where the impedance is purely real, in this case, the battery diagnostic device (100) can determine that the battery cell has a problem with its internal resistance.

[0097] The battery diagnostic device (100) can compare the slope of the third line (322) with the slope of the portion of the reference line corresponding to the third line (322). The battery diagnostic device (100) can determine that the battery cell is defective if the slope of the third line (322) deviates from a preset range of the slope of the portion of the reference line corresponding to the third line (322). In this case, the battery diagnostic device (100) can determine that there is a problem with the diffusion effect inside the battery cell.

[0098] The battery diagnostic device (100) can 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 of the reference plot corresponding to the second line (321). The battery diagnostic device (100) can determine that the battery cell is defective if the location of the radius of curvature of the second line (321) or the inflection point of the Nyquist plot (320) deviates by more than a preset range from the radius of curvature or the inflection point of the portion of the reference plot corresponding to the second line (321). In this case, the battery diagnostic device (100) can determine that the battery cell has a problem with charge transfer.

[0099] The battery diagnostic device (100) can determine that the battery cell is normal if the Nyquist plot (320) corresponds to the reference plot (420). Specifically, the battery diagnostic device (100) can determine that the battery cell is normal if the position of the first X-intercept (330) does not exceed a preset range from the position of the second X-intercept (430), the slope of the third line (322) does not exceed a preset range from the slope of the fifth line (421), and the radius of curvature of the second line (321) and the position of the first inflection point (340) do not exceed a preset range from the radius of curvature of the fifth line (421) and the position of the second inflection point (440).

[0100] FIG. 9 shows a computing system that executes a battery diagnostic method according to one embodiment disclosed in this document.

[0101] Referring to FIG. 8, a computing system (500) according to one embodiment disclosed in this document may include an MCU (510), memory (520), input / output I / F (530) and communication I / F (540).

[0102] The MCU (510) may be a processor that executes various programs stored in memory (520) (e.g., SOH calculation program, cell balancing target determination program, etc.), processes various data including SOC, SOH, etc. of a plurality of battery cells (11) through these programs, and performs the functions of the battery diagnostic device (100) described with reference to FIGS. 1 to 7.

[0103] The memory (520) can store various programs regarding the calculation of the SOH of the battery cells (11) and the determination of the target for cell balancing. In addition, the memory (520) can store various data such as the SOC and SOH data of each of the battery cells (11).

[0104] These memories (520) may be provided in multiple quantities as needed. The memories (520) may be volatile memories or non-volatile memories. As volatile memories, the memory (520) may use RAM, DRAM, SRAM, etc. As non-volatile memories, the memory (520) may use ROM, PROM, EAROM, EPROM, EEPROM, flash memory, etc. The examples of the memories (520) listed above are merely examples and are not limited to these examples.

[0105] The input / output I / F (530) can provide an interface that enables data transmission and reception between an input device (not shown), such as a keyboard, mouse, or touch panel, and an output device (not shown), such as a display, and the MCU (510).

[0106] The communication I / F (540) is configured to transmit and receive various data to and from a server and may be various devices capable of supporting wired or wireless communication. For example, through the communication I / F (540), programs for calculating the SOH of battery cells (11) or determining the balancing target, or various data, can be transmitted and received from an external server provided separately.

[0107] As such, a battery diagnostic method according to one embodiment disclosed in this document can be recorded in memory (520) and executed by an MCU (510).

[0108] The above description is merely an illustrative explanation of the technical concept disclosed in this document, and a person skilled in the art to which the embodiments disclosed in this document belong may make various modifications and variations within the scope of the essential characteristics of the embodiments disclosed in this document.

[0109] Accordingly, the embodiments disclosed in this document are intended to illustrate, not limit, the technical concept disclosed in this document, and the scope of the technical concept disclosed in this document is not limited by these embodiments. The scope of protection of the technical concept disclosed in this document shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of this document. Explanation of the symbols

[0110] 11: Battery cells 100: Battery Diagnostic Device 110: Information Acquisition Department 120: Storage section 130: Controller

Claims

Claim 1 A battery diagnostic device comprising: an information acquisition unit that receives output signals 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 the output signals with a reference signal to determine whether correction is required, corrects the output signals to generate a correction signal if correction is required, and determines the state of each of the plurality of battery cells based on the characteristics of the correction signal, wherein the controller calculates the frequency-specific impedance response of each of the plurality of battery cells based on the correction signal. Claim 2 A battery diagnostic device according to claim 1, wherein the controller determines whether correction is necessary by comparing the amplitude and phase of the output signal with the amplitude and phase of a reference signal, respectively, and, if correction is necessary, corrects the amplitude or phase of the output signal to generate a correction signal. Claim 3 A battery diagnostic device comprising: an information acquisition unit receiving output signals from each of a plurality of battery cells of a battery pack to which an AC input signal is applied; and a controller that determines whether correction is required by comparing the output signals with a reference signal, and if correction is required, corrects the output signals to generate a correction signal, and determines the state of each of the plurality of battery cells based on the characteristics of the correction signal, wherein the controller determines whether correction is required by comparing the amplitude and phase of the output signals with the amplitude and phase of the reference signal, and if correction is required, corrects the amplitude or phase of the output signals to generate a correction signal, wherein the plurality of battery cells includes n battery cells, the amplitude of the reference signal corresponds 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. Claim 4 In claim 3, the controller is a battery diagnostic device that corrects the amplitude or phase of the output signal to correspond to the amplitude or phase of the reference signal. Claim 5 delete Claim 6 In claim 1, the controller is a battery diagnostic device that determines the state of each of the plurality of battery cells based on the frequency-specific impedance response. Claim 7 In claim 1, the controller is a battery diagnostic device that generates a Nyquist diagram based on the frequency-dependent impedance response of each of the plurality of battery cells. Claim 8 In claim 7, the controller is a battery diagnostic device that determines the state of each of the plurality of battery cells by comparing the Nyquist plot and the reference plot. Claim 9 In claim 8, the controller is a battery diagnostic device that compares the slope, X-intercept, or inflection point of the Nyquist plot and the reference plot, respectively. Claim 10 A battery diagnostic device comprising: an information acquisition unit that receives output signals 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 the output signals with a reference signal to determine whether correction is required, corrects the output signals to generate a correction signal if correction is required, and determines the state of each of the plurality of battery cells based on the characteristics of the correction signal, wherein the sum of the amplitudes of the output signals obtained from each of the plurality of battery cells corresponds to the amplitude of the AC input signal applied to the battery pack including the plurality of battery cells. Claim 11 In claim 1, the information acquisition unit is a battery diagnostic device connected to each of the battery cells included in the plurality of battery cells. Claim 12 A battery diagnostic method comprising: a step of applying an AC input signal to a plurality of battery cells; a step of receiving an output signal from each of the plurality of battery cells and correcting the output signal to generate a correction signal; and a step of determining the state of each of the plurality of battery cells based on the characteristics of the correction signal, wherein the step of determining the state includes a step of calculating a frequency-dependent impedance response of each of the plurality of battery cells based on the correction signal and a step of determining the state of each of the plurality of battery cells based on the frequency-dependent impedance response. Claim 13 A battery diagnostic method according to claim 12, wherein the step of generating the correction signal is to determine whether correction is necessary by comparing the amplitude and phase of the output signal with the amplitude and phase of a reference signal, respectively, and to generate the correction signal if correction is necessary. Claim 14 A battery diagnostic method comprising: a step of applying an AC input signal to a plurality of battery cells; a step of receiving an output signal from each of the plurality of battery cells and correcting the output signal to generate a correction signal; and a step of determining the state of each of the plurality of battery cells based on the characteristics of the correction signal, wherein the step of generating the correction signal includes comparing the amplitude and phase of the output signal with the amplitude and phase of a reference signal, respectively, to determine whether correction is necessary, and if correction is necessary, generating the correction signal, wherein the plurality of battery cells includes n battery cells, the amplitude of the reference signal corresponds 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. Claim 15 A battery diagnostic method according to claim 14, wherein the step of generating the correction signal comprises the step of correcting the amplitude or phase of the output signal to correspond to the amplitude or phase of the reference signal. Claim 16 delete Claim 17 A battery diagnostic method comprising: a step of applying an AC input signal to a plurality of battery cells; a step of receiving an output signal from each of the plurality of battery cells and correcting the output signal to generate a correction signal; and a step of determining the state of each of the plurality of battery cells based on the characteristics of the correction signal, wherein the sum of the amplitudes of the output signals obtained from each of the plurality of battery cells corresponds to the amplitude of the AC input signal applied to a battery pack including the plurality of battery cells.

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