Storage battery inspection device and storage battery inspection method

Abstract

A storage battery inspection device (10) comprises: a power storage control circuit (11) for applying an alternating current to a storage battery (31); a magnetic sensor (12) for sensing a magnetic field outside the storage battery (31); a calculation unit (76) for calculating an alternating current flowing through the storage battery (31) on the basis of the sensing result from the magnetic sensor (12); and a correction unit (77) for calculating one or more vectors (Iabnormal, Inormal) on a complex plane representing the alternating current flowing through the storage battery (31) on the basis of the calculation result from the calculation unit (76), calculating one or more projection vectors (I'abnormal, I'normal) obtained by projecting the calculated one or more vectors (Iabnormal, Inormal) onto a predetermined straight line on the complex plane, and outputting a correction signal indicating the magnitude of the calculated one or more projection vectors (I'abnormal, I'normal).

Description

Battery inspection device and battery inspection method

[0001] The present disclosure relates to a storage battery inspection device that inspects a storage battery.

[0002] Patent Document 1 discloses a technology related to an evaluation device for inspecting secondary batteries. In the technology described in Patent Document 1, a controller calculates the magnitude of each of multiple currents flowing through multiple parts of the secondary battery from a magnetic field detected by a magnetic sensor, and extracts the magnitude of multiple currents in an electrolyte region located between the electrodes. The controller then creates a graph showing the distribution of the magnitude of the multiple currents and displays it on a display device. Note that secondary batteries are also called storage batteries.

[0003] JP 2013-32985 A

[0004] Here, when an initial abnormality that occurs inside the storage battery is detected using a magnetic sensor outside the battery, the magnetic sensor and the abnormal location are separated by a certain distance, so magnetic field lines resulting from the current flowing through various parts of the storage battery are applied to the sensing surface of the magnetic sensor, making it difficult to accurately visualize which part of the storage battery is abnormal.

[0005] Therefore, it is difficult to identify an abnormality by the magnitude of the current calculated by a method other than analytical methods based on the magnetic field outside the storage battery. In addition, even if an image is created by analytical methods, it is essential to properly process the data used as boundary conditions before calculation. For example, the evaluation device in Patent Document 1 is not based on a solution to an analytical inverse problem and cannot properly inspect a storage battery.

[0006] Therefore, the present disclosure provides a storage battery inspection device and the like that can more appropriately inspect storage batteries.

[0007] A battery inspection device according to one aspect of the present disclosure includes an application unit that applies an AC current to a battery; a sensing unit that senses a magnetic field external to the battery; a calculation unit that calculates the AC current flowing through the battery based on the sensing result of the sensing unit; and a correction unit that calculates one or more vectors on a complex plane that represent the AC current flowing through the battery based on the calculation result of the calculation unit, calculates one or more projection vectors by projecting the calculated one or more vectors onto a predetermined straight line on the complex plane, and outputs a correction signal that indicates the magnitude of the calculated one or more projection vectors.

[0008] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0009] According to one aspect of the present disclosure, a storage battery can be inspected more appropriately.

[0010] FIG. 1 is a block diagram showing the configuration of a storage battery inspection device according to an embodiment. FIG. 2 is a flowchart showing the operation of the storage battery inspection device according to an embodiment. FIG. 3 is a conceptual diagram showing a specific configuration of the storage battery inspection device according to an embodiment. FIG. 4 is a conceptual diagram showing a specific structure of a magnetic sensor according to an embodiment. FIG. 5 is a conceptual diagram showing a storage battery being inspected according to an embodiment. FIG. 6 is a conceptual diagram showing a circuit for applying an AC voltage according to an embodiment. FIG. 7 is a conceptual diagram showing the overall configuration of a storage battery inspection device according to an embodiment. FIG. 8 is a block diagram showing the configuration of a detection circuit according to an embodiment. FIG. 9 is a conceptual diagram showing AC current flowing through a storage battery according to an embodiment. FIG. 10 is a diagram showing complex numbers on a complex plane representing AC current flowing through a storage battery according to an embodiment, projected onto the vertical axis. FIG. 11 is a diagram showing an image generated based on the projected complex numbers shown in FIG. 10. FIG. 12 is a diagram showing complex numbers on a complex plane representing AC current flowing through a storage battery according to an embodiment, projected onto a predetermined line. FIG. 13 is a diagram showing an image generated based on the projected complex numbers shown in FIG. 12.

[0011] A battery inspection device according to one aspect of the present disclosure includes an application unit that applies an AC current to a battery; a sensing unit that senses a magnetic field external to the battery; a calculation unit that calculates the AC current flowing through the battery based on the sensing result of the sensing unit; and a correction unit that calculates one or more vectors on a complex plane that represent the AC current flowing through the battery based on the calculation result of the calculation unit, calculates one or more projection vectors by projecting the calculated one or more vectors onto a predetermined straight line on the complex plane, and outputs a correction signal that indicates the magnitude of the calculated one or more projection vectors.

[0012] This allows for the calculation of one or more vectors on a complex plane representing the AC current flowing through the storage battery, the calculation of one or more projection vectors by projecting the one or more vectors onto a predetermined line on the complex plane, and the output of a correction signal indicating the magnitude of the one or more projection vectors. Therefore, when an abnormality occurs in the storage battery, a vector representing the AC current flowing through the abnormal location and a vector representing the AC current flowing through a normal location near the abnormal location can be calculated. Furthermore, while it is difficult to distinguish between abnormal and normal locations simply by outputting the magnitudes of these vectors, as described above, by calculating the projection vectors and outputting their magnitudes, it becomes easier to differentiate between output values ​​indicating the magnitude of the AC current at the abnormal location and output values ​​indicating the magnitude of the AC current at the normal location. This makes it easier to distinguish between abnormal and normal locations, allowing for more appropriate battery inspection.

[0013] For example, the storage battery has a body and electrode terminals connected to the body, and the predetermined straight line is perpendicular to a vector on the complex plane that represents an alternating current flowing throughout the body.

[0014] This allows the output of the magnitude of one or more projected vectors projected onto a line perpendicular to a vector on a complex plane representing the AC current flowing throughout the entire battery. For example, the phase of the AC current flowing through an abnormal location in the battery lags behind the phase of the AC current flowing throughout the entire battery, and accordingly, the phase of the AC current flowing through a normal location in the battery advances relative to the phase of the AC current flowing throughout the entire battery. In other words, the direction of the vector representing the AC current flowing through an abnormal location in the battery is opposite to the direction of the vector representing the AC current flowing through a normal location in the battery. Therefore, by calculating the projected vectors as described above, the difference between the output value indicating the magnitude of the AC current flowing through an abnormal location in the battery and the output value indicating the magnitude of the AC current flowing through a normal location in the battery can be increased, making it easier to distinguish between abnormal and normal locations. This further enables more accurate battery testing.

[0015] Also, for example, the battery inspection device further includes a generation unit that generates an image showing the distribution of AC current flowing through the battery based on the correction signal output by the correction unit, and a display unit that displays the image generated by the generation unit.

[0016] This allows an image showing the distribution of alternating current flowing through the storage battery to be displayed, making it easier to see where in the storage battery an abnormality has occurred and allowing the storage battery to be inspected more appropriately.

[0017] Also, for example, a storage battery inspection method according to one aspect of the present disclosure includes an application unit that applies an AC current to a storage battery, a sensing unit that senses a magnetic field external to the storage battery, a calculation unit that calculates the AC current flowing through the storage battery based on the sensing result of the sensing unit, a correction unit that calculates one or more vectors on a complex plane that represent the AC current flowing through the storage battery based on the calculation result of the calculation unit, calculates one or more projection vectors by projecting the one or more calculated vectors onto a predetermined straight line on the complex plane, and outputs a correction signal that indicates the magnitude of the one or more calculated projection vectors.

[0018] This allows for the calculation of one or more vectors on a complex plane representing the AC current flowing through the storage battery, the calculation of one or more projection vectors by projecting the one or more vectors onto a predetermined line on the complex plane, and the output of a correction signal indicating the magnitude of the one or more projection vectors. Therefore, when an abnormality occurs in the storage battery, a vector representing the AC current flowing through the abnormal location and a vector representing the AC current flowing through a normal location near the abnormal location can be calculated. Furthermore, while it is difficult to distinguish between abnormal and normal locations simply by outputting the magnitudes of these vectors, as described above, by calculating the projection vectors and outputting their magnitudes, it becomes easier to differentiate between output values ​​indicating the magnitude of the AC current at the abnormal location and output values ​​indicating the magnitude of the AC current at the normal location. This makes it easier to distinguish between abnormal and normal locations, allowing for more appropriate battery inspection.

[0019] Hereinafter, embodiments will be described with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, the arrangement and connection of the components, steps, the order of steps, and the like shown in the following embodiments are merely examples and are not intended to limit the scope of the claims.

[0020] A storage battery is a battery that can be charged and discharged, and is also called a secondary battery. A magnetic field component is a component that constitutes a magnetic field. A magnetic field component may be a component corresponding to a spatial position, a component corresponding to a frequency, a component corresponding to a specific direction, or a component corresponding to any combination of these. For ease of explanation, a magnetic field component may be simply referred to as a magnetic field.

[0021] Furthermore, here, canceling out the magnetic field component is not limited to completely canceling out the magnetic field component, but may also mean almost canceling out the magnetic field component, or partially canceling out the magnetic field component, and may also mean suppressing the magnetic field component.

[0022] (Embodiment) First, an overview of a storage battery inspection device according to this embodiment will be described. The storage battery inspection device according to this embodiment inspects a storage battery without destroying the storage battery. X-rays, visible light, microwaves, and the like are sometimes used as technical elements for such non-destructive inspection. However, it is difficult to inspect the electrical state inside a storage battery using any of X-rays, visible light, and microwaves. Therefore, the storage battery inspection device according to this embodiment uses magnetic field information.

[0023] Specifically, the current flowing inside the storage battery generates a magnetic field around the storage battery (outside the storage battery). The relationship between the current (J) and the magnetic field (H) in a steady state is expressed as ΔH = -(∇ × J) based on Maxwell's equations. Based on this relationship, it is possible to estimate the current flowing inside the storage battery from the magnetic field outside the storage battery. The battery inspection device in this embodiment inspects the electrical state of the storage battery by measuring the magnetic field.

[0024] Meanwhile, the electrical state inside a battery changes during the charging and discharging process. Observing the changing state during the charging and discharging process is useful for testing the reliability of the battery. However, since measuring a magnetic field takes a considerable amount of time, the electrical state inside the battery may change while the magnetic field is being measured during the charging and discharging process. When the electrical state inside the battery changes, the magnetic field also changes, making it difficult to measure the magnetic field properly.

[0025] In such a situation, it is possible to stop the change in the electrical state of the battery by stopping the charging and discharging of the battery. However, when charging and discharging are simply stopped, no current flows in the battery and no magnetic field components corresponding to the electrical state of the battery are generated. Therefore, it is not appropriate to measure the magnetic field when charging and discharging are simply stopped.

[0026] Magnetic materials may also be used in the electrodes of storage batteries. Magnetic field components are also generated by the magnetization of the magnetic materials in such storage batteries. The strength of the magnetic field components generated by the magnetization of the magnetic materials in storage batteries may be much greater than the strength of the magnetic field components generated by the current flowing through the storage batteries. For example, the strength of the magnetic field components generated by the magnetization of the magnetic materials in storage batteries is expected to be on the order of several milliteslas, while the strength of the magnetic field components generated by the current flowing through the storage batteries is expected to be several microteslas or less.

[0027] In the above case, the magnetic sensor for measuring the magnetic field strongly reacts to the magnetic field components generated by the magnetization of the magnetic material in the storage battery, making it difficult to accurately detect the fine magnetic field components generated by the current flowing inside the storage battery.

[0028] Therefore, the battery inspection device in this embodiment first applies an AC current to the battery. This allows the battery inspection device to pass an AC current through the battery while pausing (suppressing) charging and discharging during the charging and discharging process of the battery. The AC current flowing through the battery also generates a magnetic field component outside the battery.

[0029] Furthermore, the battery inspection device in this embodiment uses a cancel coil to cancel magnetic field components with frequencies lower than the frequency of the AC current, thereby enabling the battery inspection device to cancel magnetic field components generated by magnetization of the magnetic body of the battery while maintaining magnetic field components generated by the AC current applied to the battery.

[0030] Therefore, the battery inspection device in this embodiment can appropriately sense the magnetic field component generated by the AC current applied to the battery.

[0031] Furthermore, the battery inspection device of this embodiment calculates one or more vectors on a complex plane representing the AC current flowing through the battery based on the sensed magnetic field components, calculates one or more projected vectors by projecting the calculated one or more vectors onto a predetermined line, and outputs the magnitudes of the calculated one or more projected vectors. This may make it possible to make the output value indicating the magnitude of the AC current flowing through an abnormal location in the battery different from the output value indicating the magnitude of the AC current flowing through a normal location nearby the abnormal location. In this case, it becomes easier to distinguish between abnormal locations and normal locations, allowing the electrical condition of the battery to be appropriately inspected. The specific configuration of the battery inspection device of this embodiment is described below.

[0032] Fig. 1 is a block diagram showing the configuration of a storage battery inspection device according to the present embodiment. The storage battery inspection device 10 shown in Fig. 1 includes a power storage control circuit 11, a magnetic sensor 12, a preamplifier 18, a cancel coil 13, a feedback circuit 14, a high-pass filter (HPF) 19, a detection circuit 15, an imaging circuit 16, and a display 17.

[0033] The power storage control circuit 11 is a circuit that applies voltage and current to the storage battery. Specifically, the power storage control circuit 11 applies an external voltage to the storage battery, in which an AC voltage is superimposed on a DC voltage to balance the output voltage of the storage battery, thereby applying an AC current to the storage battery. In this embodiment, the power storage control circuit 11 corresponds to the application unit.

[0034] The magnetic sensor 12 is a sensor that senses magnetic field components. Specifically, the magnetic sensor 12 senses magnetic field components outside the storage battery and outputs a magnetic sensor signal indicating the sensed magnetic field components. For example, the strength of the magnetic sensor signal output from the magnetic sensor 12 is proportional to the strength of the magnetic field components sensed by the magnetic sensor 12. In this embodiment, the magnetic sensor 12 corresponds to a sensing unit.

[0035] The preamplifier 18 is a circuit that amplifies a small signal, thereby obtaining a signal that can be used by subsequent circuits (such as the feedback circuit 14 and the high-pass filter 19). For example, the preamplifier 18 amplifies the magnetic sensor signal output from the magnetic sensor 12 and outputs the amplified magnetic sensor signal. In the present disclosure, the magnetic sensor signal output from the magnetic sensor 12 may be the magnetic sensor signal output from the magnetic sensor 12 and amplified by the preamplifier 18.

[0036] The canceling coil 13 is a circuit that generates a magnetic field component based on the input current. Specifically, the canceling coil 13 generates a magnetic field component based on the input current to cancel out the magnetic field component generated by the magnetization of the magnetic material in the storage battery.

[0037] Feedback circuit 14 is a circuit that applies a current as an input current to cancel coil 13 based on the magnetic sensor signal output from magnetic sensor 12. Specifically, feedback circuit 14 acquires a low-frequency signal that indicates a magnetic field component with a frequency lower than the frequency of the AC current from the magnetic sensor signal output from magnetic sensor 12 when AC current is applied to the storage battery.

[0038] For example, the strength of the low-frequency signal is proportional to the strength of magnetic field components at frequencies lower than the frequency of the alternating current. The low-frequency signal may represent magnetic field components at all frequencies lower than the frequency of the alternating current, or may represent magnetic field components at some frequencies lower than the frequency of the alternating current. Specifically, the low-frequency signal may represent magnetic field components at frequencies lower than a reference frequency lower than the frequency of the alternating current. Alternatively, the low-frequency signal may represent magnetic field components corresponding to a direct current component.

[0039] Then, based on the low-frequency signal, feedback circuit 14 applies a current as an input current to canceling coil 13. More specifically, the larger the low-frequency signal acquired from the magnetic sensor signal, that is, the larger the magnetic field component of a frequency lower than the frequency of the AC current, the larger the current that feedback circuit 14 applies to canceling coil 13 as an input current.

[0040] The high-pass filter 19 is a filter that blocks frequency components lower than the cutoff frequency and passes frequency components higher than the cutoff frequency. The cutoff frequency of the high-pass filter 19 is set to a frequency lower than the frequency of the AC current applied to the storage battery 31. This removes frequency components from the magnetic sensor signal that are lower than the frequency of the AC current applied to the storage battery 31 and lower than the cutoff frequency.

[0041] Here, blocking frequency components lower than the cutoff frequency means suppressing passage of frequency components lower than the cutoff frequency, and is not limited to completely blocking frequency components lower than the cutoff frequency. Similarly, passing frequency components higher than the cutoff frequency means suppressing blocking of frequency components higher than the cutoff frequency, and is not limited to completely passing frequency components higher than the cutoff frequency. The degree of blocking and passing depends on the quality of the high-pass filter 19.

[0042] Moreover, the high-pass filter 19 may block or pass components having the same frequency as the cutoff frequency, or may block part of the components having the same frequency as the cutoff frequency and pass the other part.

[0043] In the present disclosure, the magnetic sensor signal output from the magnetic sensor 12 may be a magnetic sensor signal output from the magnetic sensor 12 and having low-frequency components removed by a high-pass filter 19. This magnetic sensor signal is input to the detection circuit 15.

[0044] The detection circuit 15 is a circuit that performs detection, such as phase detection. Specifically, the detection circuit 15 obtains, as a detection signal, a signal that indicates a magnetic field component having the same frequency as the frequency of the AC current applied to the storage battery. More specifically, when an AC current is applied to the storage battery and an input current is applied to the cancel coil 13, the detection circuit 15 obtains, from the magnetic sensor signal output from the magnetic sensor 12, a detection signal that indicates a magnetic field component having the same frequency as the AC current.

[0045] For example, the strength of the detection signal is proportional to the strength of the magnetic field component of the same frequency as the frequency of the alternating current.

[0046] The imaging circuit 16 is a circuit that generates an image and has a calculation unit 76, a correction unit 77, and a generation unit 78. Specifically, the imaging circuit 16 generates an image that indicates the state of the storage battery based on the detection signal from the detection circuit 15. Here, the image can also be expressed as a video.

[0047] The calculation unit 76 calculates the AC current flowing through the storage battery based on the detection result of the magnetic sensor 12. Specifically, the magnetic sensor 12 senses magnetic field components at each of a plurality of positions outside the storage battery, and the calculation unit 76 calculates the AC current flowing through each of a plurality of positions inside the storage battery by calculating the AC current based on the magnetic field components at each of the plurality of positions. The calculation unit 76 acquires the detection result of the magnetic sensor 12 via the detection circuit 15, etc.

[0048] The correction unit 77 calculates one or more vectors on a complex plane that represent the AC current flowing through the storage battery, based on the calculation result of the calculation unit 76. The correction unit 77 also calculates one or more projected vectors by projecting the one or more calculated vectors onto a predetermined straight line on the complex plane, and outputs a correction signal that indicates the magnitude of the one or more calculated projected vectors.

[0049] The generation unit 78 generates an image showing the distribution of the AC current flowing through the storage battery based on the correction signal output by the correction unit 77 .

[0050] Display 17 is a device (information display circuit) that displays the image generated by generation unit 78. Specifically, display 17 has a screen, and displays the image generated by imaging circuit 16 on the screen. In this embodiment, display 17 corresponds to the display unit.

[0051] The battery inspection device 10 may include only some of the storage control circuit 11, magnetic sensor 12, cancel coil 13, feedback circuit 14, detection circuit 15, imaging circuit 16, and display 17. In other words, the battery inspection device 10 does not need to include all of these. For example, the display 17 may be included in a device different from the battery inspection device 10, or the imaging circuit 16 and the display 17 may be included in a device different from the battery inspection device 10.

[0052] Furthermore, the battery inspection device 10 does not necessarily have to include the preamplifier 18, the high-pass filter 19, or both. For example, the magnetic sensor signal output from the magnetic sensor 12 may be input to the feedback circuit 14 and the detection circuit 15 without passing through the preamplifier 18 or the high-pass filter 19.

[0053] Furthermore, two or more of the components constituting the battery inspection device 10 may be configured as a single circuit. Furthermore, these circuits are not limited to dedicated circuits and may be general-purpose circuits. In particular, the circuit that performs information processing may be a general-purpose circuit such as a processor that executes a program corresponding to the above processing.

[0054] Fig. 2 is a flowchart showing the operation of the storage battery inspection device 10 shown in Fig. 1. Specifically, a plurality of components of the storage battery inspection device 10 shown in Fig. 1 perform the operations shown in Fig. 2.

[0055] First, the storage control circuit 11 detects a frequency f ０ To the storage battery (S11), the power storage control circuit 11 applies an AC current to the storage battery by applying to the storage battery an external voltage in which an AC voltage is superimposed on a DC voltage for balancing the output voltage of the storage battery.

[0056] The magnetic sensor 12 senses a magnetic field component while an AC current is applied to the storage battery, and outputs a magnetic sensor signal indicating the sensed magnetic field component (S12).

[0057] The feedback circuit 14 derives the frequency f ０ Specifically, the feedback circuit 14 obtains a low-frequency signal lower than the frequency f of the AC current from the magnetic sensor signal output from the magnetic sensor 12 (S13). ０ A low frequency signal indicative of magnetic field components at frequencies lower than

[0058] The feedback circuit 14 then outputs a frequency f ０ A current is applied as an input current to the cancel coil 13 based on a low frequency signal lower than the reference frequency (S14).

[0059] The canceling coil 13 generates a magnetic field component based on the input current. Specifically, the canceling coil 13 generates a magnetic field component at a frequency f ０ and generates a low-frequency magnetic field component lower than frequency f ０ The low frequency components lower than the reference frequency are cancelled (S15).

[0060] The detection circuit 15 detects a frequency f ０ Specifically, the detection circuit 15 obtains the frequency f of the AC current from the magnetic sensor signal output from the magnetic sensor 12 (S16). ０ A detection signal indicating a magnetic field component of the same frequency as

[0061] The storage control circuit 11, magnetic sensor 12, canceling coil 13, feedback circuit 14, and detection circuit 15 continuously perform the above processing in parallel. Then, with AC current applied to the storage battery and input current applied to the canceling coil 13, magnetic sensor 12 senses magnetic field components at multiple positions around the storage battery and outputs magnetic sensor signals indicating the sensed magnetic field components.

[0062] The detection circuit 15 acquires the magnetic sensor signal output from the magnetic sensor 12 at each of a plurality of positions around the storage battery when an AC current is applied to the storage battery and an input current is applied to the cancel coil 13, and acquires a detection signal from the magnetic sensor signal.

[0063] The calculation unit 76 of the imaging circuit 16 calculates the AC current flowing through the storage battery based on the detection result of the magnetic sensor 12 and the like (S17).

[0064] The correction unit 77 of the imaging circuit 16 calculates one or more vectors on a complex plane that represent the AC current calculated by the calculation unit 76 (S18), calculates one or more projection vectors by projecting the calculated one or more vectors onto a predetermined straight line on the complex plane (S19), and outputs a correction signal that indicates the magnitude of the calculated one or more projection vectors (S20).

[0065] The generating unit 78 of the imaging circuit 16 generates an image based on the output correction signal (S21).

[0066] Then, the display 17 displays the generated image (S22).

[0067] Fig. 3 is a conceptual diagram showing a specific configuration of the battery inspection device 10 shown in Fig. 1. Fig. 3 shows the battery inspection device 10 and a battery 31. The battery inspection device 10 shown in Fig. 3 corresponds to the specific example of the battery inspection device 10 shown in Fig. 1, and includes a measurement unit 21, a power supply unit 23, a display 17, and an information processing unit 24.

[0068] For example, the power storage control circuit 11 is included in the power supply unit 23, and the imaging circuit 16 is included in the information processing unit 24. The feedback circuit 14 and the detection circuit 15 may each be included in the measurement unit 21, the information processing unit 24, or may be distributed and arranged in the measurement unit 21 and the information processing unit 24.

[0069] Measurement unit 21 includes magnetic sensor 12 as a probe, and includes cancel coil 13 near magnetic sensor 12. Measurement unit 21 measures the magnetic field via magnetic sensor 12. Measurement unit 21 also includes a slidable mechanism configured with an actuator or the like. This allows measurement unit 21 to scan the vicinity of storage battery 31 using magnetic sensor 12.

[0070] The measurement unit 21 also includes a rotating table 22. The rotating table 22 is a table on which the storage battery 31, which is the object to be inspected, is placed, and has a rotatable mechanism formed by an actuator or the like. This allows the measurement unit 21 to scan the vicinity of the storage battery 31 at various rotation angles using the magnetic sensor 12.

[0071] For example, the magnetic sensor 12 is located inside the canceling coil 13, and as the magnetic sensor 12 moves, the canceling coil 13 also moves.

[0072] Here, the storage battery 31 is rotated by the turntable 22, but the measuring unit 21 may rotate around the storage battery 31 to scan the vicinity of the storage battery 31 at various rotation angles. The measuring unit 21 may also rotate the magnetic sensor 12.

[0073] The power supply unit 23 is a device that applies a voltage and a current to the storage battery 31. Specifically, the power supply unit 23 applies an AC current to the storage battery 31 by applying to the storage battery 31 an external voltage in which an AC voltage is superimposed on a DC voltage for balancing the output voltage of the storage battery 31. The power supply unit 23 may be a function generator. In the example of Fig. 3, the power supply unit 23 applies a voltage and a current to the storage battery 31 via conductors.

[0074] The information processing unit 24 is a device that performs information processing, for example, a computer.

[0075] Specifically, information processing unit 24 may apply a current as an input current to canceling coil 13 based on a magnetic sensor signal output from magnetic sensor 12 via measurement unit 21 or the like. In this case, information processing unit 24 may acquire a low-frequency signal indicating a magnetic field component with a frequency lower than the frequency of the AC current from the magnetic sensor signal output from magnetic sensor 12 in a state where AC current is applied to storage battery 31. Then, information processing unit 24 may apply a current as an input current to canceling coil 13 based on the low-frequency signal.

[0076] Furthermore, for example, the information processing unit 24 may perform detection processing. Specifically, the information processing unit 24 acquires a detection signal indicating a magnetic field component of the same frequency as the frequency of the AC current from the magnetic sensor signal output from the magnetic sensor 12 in a state in which an AC current is applied to the storage battery 31 and an input current is applied to the cancel coil 13.

[0077] Furthermore, for example, the information processing unit 24 may calculate the AC current flowing through the storage battery 31 based on a magnetic field external to the storage battery 31. Furthermore, for example, the information processing unit 24 may calculate one or more vectors on a complex plane that represent the calculated AC current, and calculate one or more projected vectors by projecting the one or more vectors onto a predetermined straight line on the complex plane.

[0078] Furthermore, for example, the information processing unit 24 may generate an image showing the state of the storage battery 31 based on the magnitudes of one or more projection vectors. Furthermore, the information processing unit 24 may display the generated image on the display 17.

[0079] The storage battery 31 inspected by the storage battery inspection device 10 is a lithium battery, a lithium ion battery, or the like. The storage battery 31 has a pair of electrode terminals 32 and 33. Each of the electrode terminals 32 and 33 is connected to the power supply unit 23 via a conductor. Then, while the power supply unit 23 applies an alternating current to the storage battery 31, the measurement unit 21 measures the magnetic field using the magnetic sensor 12.

[0080] Note that the specific example of the storage battery inspection device 10 shown in Fig. 1 is not limited to the example shown in Fig. 3. For example, some components may be omitted, or other components may be added. Furthermore, some or all of the measurement unit 21, power supply unit 23, display 17, and information processing unit 24 shown in Fig. 3 may have an integrated structure.

[0081] Fig. 4 is a conceptual diagram showing a specific structure of the magnetic sensor 12 shown in Fig. 3. The magnetic sensor 12 is composed of a TMR (Tunneling Magneto Resistive) element.

[0082] In a TMR element, an insulating film is sandwiched between magnetic films having a thickness of about 10 nm to 100 nm. More specifically, the TMR element is composed of multiple thin films: a soft layer 25, a tunnel layer 26, and a PIN layer (magnetization fixed layer) 27. The soft layer 25 is a magnetic film whose magnetization direction changes depending on the direction of magnetization in the external environment. The PIN layer 27 is a magnetic film whose magnetization direction does not change. The tunnel layer 26 is an insulating film.

[0083] The electrical resistance differs depending on whether the magnetization direction in the soft layer 25 and the magnetization direction in the PIN layer 27 are the same or different. The magnetic field component is sensed by utilizing this change in electrical resistance.

[0084] For example, the magnetic sensor 12 uses the above-described characteristics to sense and measure magnetic field components. Note that the magnetic sensor 12 is not limited to the above example configured with a TMR element, and may be configured with other elements such as a GMR (Giant Magneto Resistive) element or a SQUID (Superconducting Quantum Interference Device) element.

[0085] Fig. 5 is a conceptual diagram showing the storage battery 31 shown in Fig. 3 being tested. The storage battery 31 shown in Fig. 5 has a main body 79 and a pair of electrode terminals 32 and 33 connected to the main body 79. The main body 79 includes a pair of electrode plates 34 and 35, an electrolyte 37, and a metal package 38. The pair of electrode plates 34 and 35 and the electrolyte 37 are covered by the metal package 38.

[0086] For example, the magnetic sensor 12 senses magnetic field components at each of a plurality of positions on the surface 41 to be scanned above the storage battery 31 placed on the turntable 22. The surface 41 to be scanned is also referred to as a measurement surface. The magnetic sensor 12 may sequentially move to a plurality of positions on the surface 41 to sense the magnetic field components. This allows information on the magnetic field components of the surface 41 to be obtained.

[0087] Furthermore, for example, the magnetic sensor 12 may sense magnetic field components at each of a plurality of positions on each of a plurality of scan target surfaces 41. Specifically, the magnetic sensor 12 may sense magnetic field components at each of a plurality of positions on one scan target surface 41, and then the magnetic sensor 12 may sense magnetic field components at each of a plurality of positions on another scan target surface 41. In this way, information on the magnetic field of each scan target surface 41 can be obtained.

[0088] Furthermore, from information on the magnetic fields of the multiple scanned surfaces 41, information on the magnetic field of a reconstruction target surface 42 different from these scanned surfaces 41 may be calculated. For example, the reconstruction target surface 42 may be a surface corresponding to the upper surface of the electrode plate 34. Specifically, information on the magnetic field of the multiple scanned surfaces 41 and Maxwell's equations may be used to calculate information on the magnetic field of the reconstruction target surface 42. Furthermore, information on the magnetic field of the scanned surface 41 or the reconstruction target surface 42 and Maxwell's equations may be used to calculate the conductivity distribution in the storage battery 31, the AC current flowing through the storage battery 31, and the like.

[0089] The calculation process as described above may be performed by the information processing unit 24 in FIG. 3 or by other components.

[0090] The current flowing inside the storage battery 31 generates a magnetic field component outside the storage battery 31. The magnetic sensor 12 senses the magnetic field component generated outside the storage battery 31 by the current flowing inside the storage battery 31. If the current flowing inside the storage battery 31 changes, the magnetic field component outside the storage battery 31 also changes. In other words, the current flowing inside the storage battery 31 can be calculated using the magnetic field component outside the storage battery 31.

[0091] For example, in the charging and discharging process of the storage battery 31, metal may be deposited on the electrode plate 34 or the electrode plate 35, causing dendrites 36 to form and grow inside the storage battery 31.

[0092] The conductivity of the dendrites 36 is higher than that of the electrolyte 37. Therefore, if the dendrites 36 are generated inside the storage battery 31, the electrical state inside the storage battery 31 changes. This causes a change in the magnetic field component outside the storage battery 31. For example, the storage battery inspection device 10 can inspect the generation and growth state of the dendrites 36 by sensing the magnetic field component outside the storage battery 31.

[0093] Meanwhile, as the dendrites 36 emerge and grow, the electrical state inside the storage battery 31 changes, which in turn changes the magnetic field components outside the storage battery 31. It takes time to sense the magnetic field components at multiple positions outside the storage battery 31, and it is not easy to sense the magnetic field components that change over time over a wide range and with high resolution.

[0094] Furthermore, by stopping the charging and discharging of the storage battery 31, the generation and growth of dendrites 36 are suppressed, and changes in the electrical state inside the storage battery 31 are also suppressed. However, when the charging and discharging of the storage battery 31 is stopped, no magnetic field components based on the electrical state inside the storage battery 31 are generated. Therefore, in this state, it is difficult to inspect the generation and growth state of the dendrites 36.

[0095] Therefore, the battery inspection device 10 applies an AC current to the storage battery 31 by applying to the storage battery 31 an external voltage in which an AC voltage is superimposed on a DC voltage for balancing the output voltage of the storage battery 31. As a result, an AC current flows in the storage battery 31 while suppressing the generation and growth of dendrites 36. The AC current flowing through the storage battery 31 generates a magnetic field component based on the electrical state inside the storage battery 31.

[0096] The battery inspection device 10 can inspect the state of occurrence and growth of dendrites 36 by sensing magnetic field components generated by the AC current flowing through the battery 31. Furthermore, the battery inspection device 10 can extract magnetic field components corresponding to the frequency of the AC current, thereby extracting magnetic field components based on the internal electrical state of the battery 31. Therefore, the battery inspection device 10 can appropriately inspect the internal electrical state of the battery 31.

[0097] However, when the frequency of the AC current is high, the magnetic field components generated by the AC current are shielded by the electrode plates 34 and 35 and the shielding parts such as the metal package 38, and do not leak outside the storage battery 31. Therefore, for example, a frequency lower than the predetermined frequency is used for the AC voltage and AC current. Here, the predetermined frequency is a frequency when the conductivity of the shielding parts is σ ｓ and the permeability of the shielding part is μ ｓ and the thickness of the shielding part is d ｓ If , 1 / (πσ ｓ μ ｓ d ｓ ２ ) As a result, a magnetic field component is generated outside the storage battery 31.

[0098] In order to suppress the influence of charging and discharging and to shorten the measurement time for the magnetic field component corresponding to the frequency of the AC current, a frequency lower than the predetermined frequency and higher than half the predetermined frequency may be used. Alternatively, a frequency lower than the predetermined frequency and higher than one-tenth of the predetermined frequency may be used. On the other hand, in order to more reliably generate the magnetic field component outside the storage battery 31, a frequency lower than half the predetermined frequency or a frequency lower than one-tenth of the predetermined frequency may be used.

[0099] Next, a more specific configuration for applying an AC voltage to the storage battery 31 will be described with reference to Fig. 6. Fig. 6 is a diagram showing a circuit for applying an AC voltage to the storage battery 31 shown in Fig. 3.

[0100] 6 shows the storage battery 31 and the storage control circuit 11. Furthermore, the capacitor C ｂ , electromotive force ν ｏ , internal resistance γｂ , DC voltage ν ｅ , AC voltage ν ａ cosωt and an external resistor γ are shown. ｂ , electromotive force ν ｏ , and internal resistance γ ｂ is included in the storage battery 31. DC voltage v ｅ , and AC voltage ν ａ cosωt is included in the storage control circuit 11. ａ The t in cosωt indicates time, and the AC voltage v ａ The ω in cosωt represents the angular frequency.

[0101] The storage control circuit 11 calculates the output voltage v of the storage battery 31 at a predetermined time t=T during the charging / discharging process. ｏ DC voltage ν to balance (T) ｅ =ν ｏ (T) AC voltage ν ａ External voltage ν cosωt superimposed Ｅ (t) = v ｅ +ν ａ cosωt is applied to the storage battery 31. For example, an external voltage v Ｅ (t) is obtained by external modulation bias (external modulation circuit and bias circuit).

[0102] In other words, the storage control circuit 11 controls the output voltage v ｏ In a state where the balance is maintained with respect to (T), charging and discharging are repeated at an angular frequency ω. The magnetic sensor 12 measures a magnetic field corresponding to a response component of the charging and discharging repeated at the angular frequency ω.

[0103] However, it is assumed that the storage battery 31 has a shielding portion that prevents the current inside the storage battery 31 from generating a magnetic field outside the storage battery 31. For example, when the AC voltage v ａ When the frequency f (f=ω / 2π) of cosωt is high, the magnetic field is shielded by the shielding parts such as the electrode plates 34 and 35 and the metal package 38 and does not leak outside the storage battery 31 .

[0104] Therefore, the storage control circuit 11 generates an AC voltage v corresponding to a frequency lower than the frequency determined based on the conductivity of the shielding portion, the magnetic permeability of the shielding portion, and the thickness (depth) of the shielding portion. ａ cosωt to DC voltage ν ｅ Specifically, when the conductivity of the shielding portion is expressed as σ, the magnetic permeability of the shielding portion is expressed as μ, and the thickness of the shielding portion is expressed as d, the power storage control circuit 11 determines whether f<1 / (πσμd ２ ) AC voltage v corresponding to frequency f satisfying ａ The thickness d of the shielding portion is, for example, the sum of the thickness of the electrode plate 34 and the thickness of the metal package 38.

[0105] After measuring the magnetic field, the power storage control circuit 11 stops superimposing the AC voltage and controls so that only charging or discharging is performed. For example, the power storage control circuit 11 applies a DC voltage greater than the output voltage of the storage battery 31 to charge the storage battery 31. Alternatively, the power storage control circuit 11 applies a DC voltage smaller than the output voltage of the storage battery 31 to discharge the storage battery 31. Alternatively, the power storage control circuit 11 may discharge the storage battery 31 without applying a voltage.

[0106] Based on the above configuration, the power storage control circuit 11 intermittently applies an external voltage in which an AC voltage is superimposed on a DC voltage to balance the output voltage of the storage battery 31 during charging and discharging. The power storage control circuit 11 may apply the external voltage in which an AC voltage is superimposed periodically (cyclically) or irregularly. The power storage control circuit 11 may apply the external voltage in which an AC voltage is superimposed automatically or manually. The magnetic sensor 12 measures the magnetic field around the storage battery 31 while the external voltage in which an AC voltage is superimposed is being applied.

[0107] For example, each time for measuring the magnetic field during the charge / discharge process may be predetermined. In this case, the power storage control circuit 11 applies an external voltage superimposed with an AC voltage to the storage battery 31 at each predetermined time during the charge / discharge process. The magnetic sensor 12 then measures the magnetic field at each predetermined time during the charge / discharge process. After the measurement, the power storage control circuit 11 controls the storage battery 31 to perform normal charging and discharging. This allows the battery inspection device 10 to measure the magnetic field corresponding to each predetermined time during the charge / discharge process.

[0108] The times for measuring the magnetic field during the charging and discharging process may be determined based on the characteristics of the output voltage of the storage battery 31 or based on the characteristics of time. In other words, the storage battery inspection device 10 may measure the magnetic field at every predetermined output voltage or at every predetermined time interval.

[0109] The imaging circuit 16 may generate a plurality of images corresponding to a plurality of times in the charge / discharge process, each of which indicates a magnetic field distribution or a current distribution. Furthermore, the imaging circuit 16 may generate a video (moving image) including a plurality of images and indicating changes in the magnetic field distribution or the current distribution by connecting the generated images. The display 17 may display the video indicating changes in the magnetic field distribution or the current distribution. This allows the user of the storage battery inspection device 10 to accurately observe the growth process of the dendrites 36.

[0110] The power storage control circuit 11 and the magnetic sensor 12 may be linked using a synchronization signal. That is, the superposition of the AC voltage and the measurement of the magnetic field may be controlled by the synchronization signal so as to start and end simultaneously.

[0111] 7 is a conceptual diagram showing the overall configuration of the storage battery inspection device 10 shown in FIG. 1. The storage control circuit 11 applies a superimposed voltage of an AC voltage and a DC voltage to the storage battery 31. Here, the DC voltage is a voltage for balancing the output voltage (also called the release voltage) of the storage battery 31, and is an offset voltage for maintaining the charged state of the storage battery 31. Specifically, the magnitude of the DC voltage is the same as the output voltage of the storage battery 31. This suppresses charging and discharging of the storage battery 31.

[0112] A superimposed voltage of an AC voltage and a DC voltage is applied to the storage battery 31, whereby an AC current is applied to the storage battery 31. For example, an AC current of about 0.1 Hz to 10 Hz is applied to the storage battery 31. Then, a magnetic field component is generated outside the storage battery 31 by the AC current applied to the storage battery 31.

[0113] The magnetic sensor 12 senses a magnetic field component generated outside the storage battery 31. The magnetic sensor 12 also scans a two-dimensional plane perpendicular to the direction toward the storage battery 31.

[0114] Meanwhile, residual magnetization of the magnetic material contained in the storage battery 31 also generates magnetic field components outside the storage battery 31. If the magnetic sensor 12 is affected by the magnetic field components generated by the residual magnetization of the magnetic material contained in the storage battery 31, it becomes difficult for the magnetic sensor 12 to properly sense the magnetic field components generated by the alternating current applied to the storage battery 31.

[0115] Therefore, the cancel coil 13 generates a magnetic field component based on the input current to cancel the magnetic field component generated by the residual magnetization. Here, the input current is a current applied to the cancel coil 13 by the feedback circuit 14. This input current is also called a feedback current.

[0116] Feedback circuit 14 includes a signal processing circuit 51 and a current amplifier circuit 52. Signal processing circuit 51 acquires the magnetic sensor signal output from magnetic sensor 12 and amplified by preamplifier 18, and outputs a control signal to current amplifier circuit 52. For example, signal processing circuit 51 acquires from the magnetic sensor signal a low-frequency signal indicating a magnetic field component with a frequency lower than the frequency of the AC current. Then, signal processing circuit 51 outputs a control signal indicating the magnitude of the feedback current to be applied to cancel coil 13 based on the low-frequency signal.

[0117] Specifically, the signal processing circuit 51 outputs a control signal that indicates a larger value as the magnitude of the feedback current as the low-frequency signal indicates a magnetic field component with a frequency lower than the frequency of the AC current.

[0118] The current amplifier circuit 52 applies to the cancel coil 13 a feedback current having a magnitude indicated by the control signal output from the signal processing circuit 51. This generates a magnetic field component that cancels out the magnetic field component generated by residual magnetization, based on a magnetic field component with a frequency lower than the frequency of the AC current.

[0119] The magnetic field components generated by residual magnetization are assumed to be composed of magnetic field components with frequencies lower than the frequency of the AC current. Therefore, the battery inspection device 10 can generate magnetic field components with the same intensity as the magnetic field components generated by residual magnetization by generating magnetic field components based on magnetic field components with frequencies lower than the frequency of the AC current. Therefore, the battery inspection device 10 can appropriately cancel out the magnetic field components generated by residual magnetization.

[0120] The detection circuit 15 acquires a magnetic sensor signal from the magnetic sensor 12. For example, the detection circuit 15 acquires the magnetic sensor signal from the magnetic sensor 12 after it has been amplified and low-frequency components have been removed via a preamplifier 18 and a high-pass filter 19. The detection circuit 15 also acquires a reference signal from the storage control circuit 11. Here, the reference signal indicates the voltage or current applied to the storage battery 31.

[0121] Specifically, the reference signal may be an AC voltage superimposed on a DC voltage in the power storage control circuit 11, or an analog signal having the same frequency and phase as the AC current applied to the storage battery 31. The reference signal may also be the same as the AC signal applied to the storage battery 31. In other words, the reference signal may be an analog signal of the same voltage and current as the voltage and current applied to the storage battery 31. Alternatively, the reference signal may be an analog signal or digital signal indicating information about the voltage or current applied to the storage battery 31.

[0122] Then, based on the magnetic sensor signal and the reference signal, the detection circuit 15 obtains, as a detection signal, a signal indicating a magnetic field component having the same frequency as the frequency of the AC current applied to the storage battery 31 .

[0123] The calculation unit 76 acquires the detection signal from the detection circuit 15. The calculation unit 76 calculates the AC current flowing through the storage battery based on the detection signal and the like.

[0124] The correction unit 77 acquires information indicating the AC current calculated by the calculation unit 76. Specifically, the correction unit 77 acquires information indicating the magnitude, phase, etc. of the AC current calculated by the calculation unit 76. Based on the acquired information, the correction unit 77 represents the AC current flowing through the storage battery 31 as a vector on a complex plane, and calculates a projection vector by projecting the vector onto a predetermined straight line. The correction unit 77 outputs a correction signal indicating the magnitude of the calculated projection vector.

[0125] The generation unit 78 acquires the correction signal from the correction unit 77. The generation unit 78 generates an image showing the state of the storage battery 31 based on the acquired correction signal. In this embodiment, this image shows the distribution of AC current flowing through the storage battery 31 as the state of the storage battery 31. Note that this image may also show magnetic field components near the surface of the storage battery 31, or the conductivity distribution of the storage battery 31, as the state of the storage battery 31. The imaging circuit 16 then outputs an image signal showing the generated image to the display 17.

[0126] The display 17 displays an image showing the state of the storage battery 31 based on the image signal output from the imaging circuit 16 .

[0127] Fig. 8 is a block diagram showing the configuration of the detection circuit 15 shown in Fig. 7. In the example of Fig. 8, the detection circuit 15 includes a DI (direct injection box) 71, an ADC (analog-to-digital converter) 72, a mixer 73, and a low-pass filter 74, and performs phase detection. Note that although an example of phase detection is shown here, the detection circuit 15 may obtain a detection signal using other methods.

[0128] The DI 71 is an impedance converter. Specifically, the DI 71 acquires a reference signal output from the power storage control circuit 11, adjusts the ratio of the voltage and current of the reference signal, and generates a reference signal for phase detection. For example, the reference signal is generated as a digital signal.

[0129] The ADC 72 is a converter for converting an analog signal into a digital signal. A 16-bit AD converter or the like can be used as the ADC 72. The ADC 72 acquires the magnetic sensor signal output from the magnetic sensor 12 as an analog signal and converts the acquired magnetic sensor signal into a digital signal.

[0130] The mixer 73 is a circuit that mixes multiple signals. Specifically, the mixer 73 multiplies the reference signal generated by the DI 71 by the magnetic sensor signal converted into a digital signal by the ADC 72, and outputs the multiplication result as a multiplication result signal. The DC component of the multiplication result signal corresponds to the magnetic field component of the same frequency as the AC current frequency.

[0131] The low-pass filter 74 is a filter that blocks frequency components higher than the cutoff frequency and passes frequency components lower than the cutoff frequency. The low-pass filter 74 acquires the multiplication result signal, blocks the AC component of the multiplication result signal, and passes the DC component of the multiplication result signal. As a result, the low-pass filter 74 outputs a detection signal corresponding to a magnetic field component having the same frequency as the AC current frequency.

[0132] The detection circuit 15 stores the detection signal in the memory circuit 75. In the above example, a digital circuit system is applied to the detection circuit 15, but an analog circuit system may also be applied to the detection circuit 15. In other words, the detection circuit 15 may obtain a detection signal indicating a magnetic field component with the same frequency as the AC current by performing detection processing on the magnetic sensor signal as an analog signal.

[0133] The imaging circuit 16 generates an image showing the state of the storage battery 31 based on the detection signal stored in the memory circuit 75. The generation of an image by the imaging circuit 16 will be described below with reference to Figs. 9 to 13.

[0134] FIG. 9 is a conceptual diagram showing an AC current flowing through storage battery 31 in the embodiment. FIG. 10 is a diagram showing complex numbers (one or more projected vectors) obtained by projecting complex numbers (one or more vectors) on a complex plane representing AC current flowing through storage battery 31 in the embodiment onto the vertical axis. FIG. 11 is a diagram showing an image generated based on the projected complex numbers (one or more projected vectors) shown in FIG. 10. FIG. 12 is a diagram showing complex numbers (one or more projected vectors) obtained by projecting complex numbers (one or more vectors) on a complex plane representing AC current flowing through the storage battery in the embodiment onto a predetermined line. FIG. 13 is a diagram showing an image generated based on the projected complex numbers (one or more projected vectors) shown in FIG. 12.

[0135] 9, when an AC current is applied to the storage battery 31 by the power storage control circuit 11, an AC current flows through the storage battery 31. Specifically, an AC current input from one electrode terminal 32 (see arrow A in FIG. 9) passes through various paths inside the main body 79 and is output from the other electrode terminal 33 (see arrow B in FIG. 9). The AC current flowing through the entire main body 79 is approximately equal to the AC current flowing through the electrode terminal 32 and is also approximately equal to the AC current flowing through the electrode terminal 33.

[0136] The magnetic sensor 12 moves relative to the storage battery 31 to sense the magnetic field at a plurality of positions outside the storage battery 31. Note that a plurality of magnetic sensors 12 may be used to sense the magnetic field at a plurality of positions outside the storage battery 31.

[0137] The calculation unit 76 calculates the AC current flowing through each of the multiple positions in the storage battery 31 using the magnetic field sensed by the magnetic sensor 12. Specifically, the calculation unit 76 calculates the magnitude, phase, etc. of the AC current flowing through each of the multiple positions in the storage battery 31.

[0138] The phase of the AC current flowing through each of the multiple positions in the main body 79 is essentially equal to the phase of the AC current flowing through the electrode terminal 32 or 33. However, if an abnormality such as the generation of dendrites 36 occurs inside the main body 79, the phase of the AC current flowing through the abnormal location in the main body 79 (see the dashed arrow in FIG. 9 ) will be shifted relative to the phase of the AC current flowing through the electrode terminal 32 or 33. Specifically, the phase of the AC current flowing through the abnormal location in the main body 79 lags behind the phase of the AC current flowing through the electrode terminal 32 or 33.

[0139] Accordingly, the phase of the AC current flowing through the normal portion of the main body 79 also shifts from the phase of the AC current flowing through the electrode terminal 32 or 33. Specifically, the phase of the AC current flowing through the normal portion of the main body 79 leads the phase of the AC current flowing through the electrode terminal 32 or 33.

[0140] The magnitude of the AC current flowing through the abnormal portion in the main body 79 is approximately equal to the magnitude of the AC current flowing through a normal portion in the vicinity of the abnormal portion.

[0141] As shown in Fig. 10 , the correction unit 77 calculates one or more vectors on a complex plane representing the AC current flowing through the storage battery 31 based on the calculation result of the calculation unit 76. In Fig. 10 , the vertical axis represents the capacitance component (imaginary part), and the horizontal axis represents the resistance component (real part). In the complex plane, the length of the vector indicates the magnitude of the AC current, and the angle between the vector and the horizontal axis indicates the phase of the AC current. For example, the calculation unit 76 calculates the effective value (magnitude) and phase of the AC current, and the correction unit 77 calculates one or more vectors on the complex plane representing the AC current flowing through the storage battery 31 based on the effective value and phase of the AC current calculated by the calculation unit 76.

[0142] Here, the correction unit 77 calculates a vector I representing the AC current flowing through the entire main body 79, that is, the AC current flowing through the electrode terminal 32 or 33. ａｌｌ , a vector I representing an AC current flowing through an abnormal portion in the main body 79 ａｂｎｏｒｍａｌ , and a vector I representing an AC current flowing through a normal portion of the main body 79. ｎｏｒｍａｌ Calculate.

[0143] Vector I ａｂｎｏｒｍａｌ is a vector obtained by adding together one or more vectors representing AC currents flowing through one or more abnormal locations in the main body 79. For example, if there are two abnormal locations in the main body 79, the vector obtained by adding together a vector representing AC currents flowing through one of the two abnormal locations and a vector representing AC currents flowing through the other of the two abnormal locations is vector I. ａｂｎｏｒｍａｌ This becomes:

[0144] Similarly, the vector I ｎｏｒｍａｌ is a vector obtained by adding together one or more vectors representing AC currents flowing through one or more normal locations in the main body 79. For example, if there are two normal locations in the main body 79, the vector obtained by adding together a vector representing an AC current flowing through one of the two normal locations and a vector representing an AC current flowing through the other of the two normal locations is vector I ｎｏｒｍａｌ This becomes:

[0145] And the vector I ａｂｎｏｒｍａｌ and vector I ｎｏｒｍａｌ The sum of these is the vector I ａｌｌ This becomes:

[0146] Vector I ａｂｎｏｒｍａｌ The angle that the vector I makes with the horizontal axis is ａｌｌ is smaller than the angle it forms with the horizontal axis, and it can be seen that the phase of the AC current flowing through the abnormal location lags behind the phase of the AC current flowing through the electrode terminal 32 or 33. ｎｏｒｍａｌ The angle that the vector I makes with the horizontal axis is ａｌｌ is larger than the angle with the horizontal axis, and it can be seen that the phase of the AC current flowing through the normal portion leads the phase of the AC current flowing through the electrode terminal 32 or 33.

[0147] If no abnormality occurs in the main body 79, the vector I ａｂｎｏｒｍａｌ is not calculated, and the vector I ｎｏｒｍａｌ is the vector I ａｌｌ In other words, the vector I ｎｏｒｍａｌ and vector I ａｌｌ If the values ​​are equal, it is understood that no abnormality has occurred in the main body 79.

[0148] The correction unit 77 calculates the vector I ａｂｎｏｒｍａｌ and vector I ｎｏｒｍａｌ When the vector I ａｂｎｏｒｍａｌ Projected vector I' onto a predetermined line ａｂｎｏｒｍａｌ , and vector I ｎｏｒｍａｌ Projected vector I' onto a predetermined line ｎｏｒｍａｌ Calculate.

[0149] 10, a case will be described in which the predetermined straight line is the vertical axis. ａｂｎｏｒｍａｌ and the projection vector I' ｎｏｒｍａｌ When the projection vector I' is calculated, ａｂｎｏｒｍａｌ and the magnitude and direction of the projection vector I′ ｎｏｒｍａｌ The signal output from the sensor is a correction signal indicating the magnitude and direction of the signal.

[0150] As shown in Fig. 11 , the generation unit 78 generates an image showing the distribution of AC current in the storage battery 31 based on the correction signal, and the display 17 displays the image. In the image of Fig. 11 , the darker the color, the greater the magnitude of the AC current indicated by the projection vector. Looking at the image of Fig. 11 , it can be seen that the color tends to become darker toward the electrode terminals 32 and 33 in the main body 79, and that the magnitude of the AC current indicated by the projection vector tends to increase.

[0151] Here, when the predetermined straight line is the vertical axis, the projection vector I' ａｂｎｏｒｍａｌ is the projection vector I' ｎｏｒｍａｌ Therefore, the magnitude of the AC current indicated by the projection vector at an abnormal location is approximately equal to the magnitude of the AC current indicated by the projection vector at a normal location near the abnormal location.

[0152] Therefore, although it is difficult to distinguish between abnormal and normal portions in the image of FIG. 11, it is possible to easily distinguish between portions of the storage battery 31 where the magnitude of the AC current is high and portions where it is low.

[0153] Next, another example of the predetermined straight line will be described. In FIG. 12, the predetermined straight line is a vector I ａｌｌ The correction unit 77 calculates the vector I ａｌｌ Calculate the line C perpendicular to the vector I ａｂｎｏｒｍａｌ Projected vector I' onto the line C ａｂｎｏｒｍａｌ , and vector I ｎｏｒｍａｌ Projected vector I' onto the line C ｎｏｒｍａｌ and calculate the projection vector I' ａｂｎｏｒｍａｌ and the magnitude and direction of the projection vector I′ ｎｏｒｍａｌ The signal output from the sensor is a correction signal indicating the magnitude and direction of the signal.

[0154] As shown in Fig. 13, the generation unit 78 generates an image showing the distribution of AC current in the storage battery 31 based on the correction signal, and the display 17 displays the image. In the image of Fig. 13, as in the image of Fig. 11, the darker the color, the greater the magnitude of the AC current indicated by the projection vector. From the image of Fig. 13, it can be seen that the color of part of the main body 79 is darker.

[0155] Here, the predetermined line is a vector I ａｌｌ If the line C is perpendicular to the ａｂｎｏｒｍａｌ is the projection vector I' ｎｏｒｍａｌ Therefore, it is possible to increase the difference between the magnitude of the AC current indicated by the projection vector at an abnormal location and the magnitude of the AC current indicated by the projection vector at a normal location near the abnormal location. ａｂｎｏｒｍａｌ The direction in which the arrow is pointing is considered the positive side.

[0156] That is, in the image of FIG. 13, darker colored portions indicate abnormal portions, and in the image of FIG. 13, abnormal portions and normal portions can be easily distinguished.

[0157] Note that the predetermined line is a vector I ａｌｌ In the above description, the predetermined line is a line perpendicular to the vector I. ｎｏｒｍａｌ or a straight line perpendicular to the vector I ａｂｎｏｒｍａｌ For example, the predetermined line may be a line perpendicular to the vector I ａｌｌ is not orthogonal to the projection vector I' ｎｏｒｍａｌ Orientation of and projection vector I' ａｂｎｏｒｍａｌ Alternatively, the direction of the line may be opposite to that of the line.

[0158] The battery inspection device 10 according to the embodiment has been described above.

[0159] The storage battery inspection device 10 in the embodiment includes a power storage control circuit 11 that applies an AC current to the storage battery 31, a magnetic sensor 12 that senses a magnetic field outside the storage battery 31, a calculation unit 76 that calculates the AC current flowing through the storage battery 31 based on the detection result of the magnetic sensor 12, and one or more vectors I on a complex plane that represent the AC current flowing through the storage battery 31 based on the calculation result of the calculation unit 76. ａｂｎｏｒｍａｌ , I ｎｏｒｍａｌ Calculate one or more calculated vectors I ａｂｎｏｒｍａｌ , I ｎｏｒｍａｌ One or more projection vectors I' obtained by projecting ａｂｎｏｒｍａｌ , I' ｎｏｒｍａｌ and calculate one or more calculated projection vectors I′. ａｂｎｏｒｍａｌ , I' ｎｏｒｍａｌ and a correction unit 77 that outputs a correction signal indicating the magnitude of the

[0160] As a result, one or more vectors I on the complex plane representing the AC current flowing through the storage battery 31 are ａｂｎｏｒｍａｌ , I ｎｏｒｍａｌ Calculate one or more vectors I ａｂｎｏｒｍａｌ , I ｎｏｒｍａｌ One or more projection vectors I' obtained by projecting ａｂｎｏｒｍａｌ , I' ｎｏｒｍａｌ and calculate one or more projection vectors I'. ａｂｎｏｒｍａｌ , I' ｎｏｒｍａｌTherefore, when an abnormality occurs in the storage battery 31, a correction signal indicating the magnitude of the vector I ａｂｎｏｒｍａｌ and a vector I representing the AC current flowing through a normal location near the abnormal location. ｎｏｒｍａｌ Furthermore, it is difficult to distinguish between abnormal and normal portions by simply outputting the magnitude of these vectors. However, as described above, the projection vector I' ａｂｎｏｒｍａｌ , I' ｎｏｒｍａｌ By calculating and outputting these magnitudes, it becomes easier to make the output value indicating the magnitude of the AC current at the abnormal location different from the output value indicating the magnitude of the AC current at the normal location. This makes it easier to distinguish between the abnormal location and the normal location, allowing the storage battery 31 to be inspected more appropriately.

[0161] In the storage battery inspection device 10 according to the embodiment, the storage battery 31 has a main body 79 and electrode terminals 32 and 33 connected to the main body 79, and the predetermined straight line is a vector I on a complex plane representing an AC current flowing through the entire main body 79. ａｌｌ is perpendicular to

[0162] As a result, a vector I on a complex plane representing an AC current flowing through the entire main body 79 of the storage battery 31 is obtained. ａｌｌ One or more projection vectors I' projected onto a line C perpendicular to ａｂｎｏｒｍａｌ , I' ｎｏｒｍａｌ For example, the phase of the AC current flowing through an abnormal portion in the main body 79 lags behind the phase of the AC current flowing through the entire main body 79, and accordingly, the phase of the AC current flowing through a normal portion in the main body 79 leads the phase of the AC current flowing through the entire main body 79. In other words, the vector I representing the AC current flowing through the entire main body 79 ａｌｌ , a vector I representing the AC current flowing through the abnormal portion in the main body 79 ａｂｎｏｒｍａｌ and a vector I representing the AC current flowing through a normal portion of the main body 79. ｎｏｒｍａｌ Therefore, the projection vector I' as described above is ａｂｎｏｒｍａｌ , I' ｎｏｒｍａｌBy calculating this, it is possible to increase the difference between the output value indicating the magnitude of the AC current flowing through the abnormal portion of the main body 79 and the output value indicating the magnitude of the AC current flowing through the normal portion of the main body 79, making it easier to distinguish between the abnormal portion and the normal portion. This allows the storage battery 31 to be inspected more appropriately.

[0163] In addition, the battery inspection device 10 in this embodiment further includes a generation unit 78 that generates an image showing the distribution of the AC current flowing through the battery 31 based on the correction signal output by the correction unit 77, and a display 17 that displays the image generated by the generation unit 78.

[0164] This allows an image showing the distribution of alternating current flowing through the storage battery 31 to be displayed, making it easier to see where in the storage battery 31 an abnormality has occurred, and further allows the storage battery 31 to be inspected more appropriately.

[0165] Although the battery inspection device has been described above based on the embodiments, the battery inspection device is not limited to the embodiments. Modifications conceivable by those skilled in the art may be made to the embodiments, and multiple components in the embodiments may be combined in any manner. For example, a process performed by a specific component in the embodiments may be performed by another component instead of the specific component. Furthermore, the order of multiple processes may be changed, and multiple processes may be performed in parallel.

[0166] Furthermore, the battery inspection method including the steps performed by each component of the battery inspection device may be executed by any device or system. For example, part or all of the battery inspection method may be executed by a computer including a processor, a memory, an input / output circuit, etc. In this case, the battery inspection method may be executed by the computer executing a program for causing the computer to execute the battery inspection method.

[0167] The above program may also be recorded on a non-transitory computer-readable recording medium.

[0168] Furthermore, each component of the storage battery inspection device may be configured with dedicated hardware, general-purpose hardware that executes the above-mentioned programs, or a combination of these. The general-purpose hardware may be configured with a memory in which the programs are recorded and a general-purpose processor that reads and executes the programs from the memory. Here, the memory may be a semiconductor memory or a hard disk, and the general-purpose processor may be a CPU.

[0169] Furthermore, the dedicated hardware may be configured with a memory, a dedicated processor, etc. For example, the dedicated processor may execute the above-described storage battery inspection method by referring to a memory for recording measurement data.

[0170] Each component of the battery testing device may be an electric circuit. These electric circuits may form a single electric circuit as a whole, or may be separate electric circuits. These electric circuits may correspond to dedicated hardware or general-purpose hardware that executes the above-mentioned program, etc.

[0171] One aspect of the present disclosure is useful for a storage battery inspection device that inspects storage batteries, and is applicable to a storage battery manufacturing system, etc.

[0172] REFERENCE SIGNS LIST 10 Storage battery inspection device 11 Power storage control circuit 12 Magnetic sensor 13 Cancellation coil 14 Feedback circuit 15 Detection circuit 16 Imaging circuit 17 Display 18 Preamplifier 19 High-pass filter (HPF) 21 Measurement unit 22 Rotating table 23 Power supply unit 24 Information processing unit 25 Soft layer 26 Tunnel layer 27 PIN layer (magnetization fixed layer) 31 Storage battery 32, 33 Electrode terminals 34, 35 Electrode plate 36 Dendrite 37 Electrolyte 38 Metal package 41 Scanning target surface 42 Reconstruction target surface 51 Signal processing circuit 52 Current amplification circuit 71 Direct injection box (DI) 72 Analog-to-digital converter (ADC) 73 Mixer 74 Low-pass filter 75 Memory circuit 76 Calculation unit 77 Correction unit 78 Generation unit 79 Main body

Claims

1. A battery inspection device comprising: an application unit that applies an AC current to a storage battery; a sensing unit that senses a magnetic field external to the storage battery; a calculation unit that calculates the AC current flowing through the storage battery based on the sensing result of the sensing unit; and a correction unit that calculates one or more vectors on a complex plane that represent the AC current flowing through the storage battery based on the calculation result of the calculation unit, calculates one or more projection vectors by projecting the one or more calculated vectors onto predetermined straight lines on the complex plane, and outputs a correction signal indicating the magnitude of the one or more calculated projection vectors.

2. The battery inspection device according to claim 1, wherein the storage battery has a main body and electrode terminals connected to the main body, and the predetermined straight line is perpendicular to a vector on the complex plane that represents an alternating current flowing throughout the main body.

3. The battery inspection device according to claim 1 or 2, further comprising: a generation unit that generates an image showing the distribution of AC current flowing through the storage battery based on the correction signal output by the correction unit; and a display unit that displays the image generated by the generation unit.

4. A battery inspection method, comprising: an application unit applying an AC current to a storage battery; a sensing unit sensing a magnetic field external to the storage battery; a calculation unit calculating the AC current flowing through the storage battery based on the sensing result of the sensing unit; a correction unit calculating one or more vectors on a complex plane representing the AC current flowing through the storage battery based on the calculation result of the calculation unit, calculating one or more projected vectors by projecting the one or more calculated vectors onto a predetermined straight line on the complex plane, and outputting a correction signal indicating the magnitude of the one or more calculated projected vectors.