Battery diagnostic device, vehicle, energy storage device, battery diagnostic method, and program

Abstract

To provide a battery diagnostic device, a vehicle, a power storage device, a battery diagnostic method, and a program capable of appropriately managing a degradation state of a battery.SOLUTION: A battery diagnostic device comprises: an acquisition unit that acquires a measurement value of a first magnetic field generated when a current is applied to a battery with a first magnetic sensor arranged in a first direction connecting current collectors of the battery; and a battery state estimation unit that estimates a degradation state of the battery on the basis of a component in the first direction of the first magnetic field.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a battery diagnostic device, a vehicle, a power storage device, a battery diagnostic method, and a program.

Background Art

[0002] Conventionally, a technique has been developed for measuring a magnetic field generated from a battery, calculating a current distribution based on the measurement result, and evaluating battery deterioration based on the current distribution (see, for example, Patent Document 1). More specifically, Patent Document 1 describes charging and discharging a battery using a first applied current and a second applied current having different current amounts, and evaluating the deterioration state at a local portion within the battery based on the difference or ratio between a first magnetic field distribution and a second magnetic field distribution generated during each charging and discharging.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional technology, although it is possible to evaluate the deterioration state of a battery at a certain point in time, there is no way to know the factors that have led the battery to such a deterioration state, and there are cases where the deterioration state of the battery cannot be appropriately managed.

[0005] The present invention has been made in consideration of such circumstances, and one of its objects is to provide a battery diagnostic device, a vehicle, a power storage device, a battery diagnostic method, and a program capable of appropriately managing the deterioration state of a battery.

Means for Solving the Problems

[0006] The battery diagnostic device, vehicle, energy storage device, battery diagnostic method, and program according to this invention employ the following configuration.

[0007] (1) A battery diagnostic device according to one aspect of the present invention includes an acquisition unit that acquires a measurement value of a first magnetic field generated when current is passed through the battery using a first magnetic sensor arranged along a first direction connecting the current collectors of the battery, and a battery state estimation unit that estimates the deterioration state of the battery based on the component of the first magnetic field in the first direction.

[0008] (2): In the embodiment of (1) above, the first magnetic sensor is positioned corresponding to the long side of the battery.

[0009] (3): In the embodiment of (1) or (2) above, the first magnetic sensor is arranged along a straight line connecting the lower ends of the current collectors.

[0010] (4) In any of the embodiments described in (1) to (3) above, the battery state estimation unit estimates that the battery is more degraded the smaller the decrease in the component of the first magnetic field in the first direction.

[0011] (5) In the embodiment of (4) above, the battery state estimation unit detects that the battery has been replaced with another battery based on the change in the slope of the curve showing the cumulative current amount with respect to the discharge time of the battery.

[0012] (6) In any of the embodiments of (1) to (5) above, the battery further comprises a second magnetic sensor that measures a second magnetic field which is a magnetic field near the current collector of the battery, and the battery state estimation unit detects a change in the state related to the deterioration of the battery based on the measurement result of the second magnetic field measured by the second magnetic sensor when current is passed through the battery.

[0013] (7) In the embodiment of (6) above, the battery state estimation unit detects a change in the state of the battery degradation based on the amount of change in the slope of the curve showing the amount of accumulated current with respect to the discharge time of the battery.

[0014] (8) In the embodiment of (6) or (7) above, the battery identification unit further identifies an individual battery based on a history of changes in the state relating to the degradation of the battery.

[0015] (9): In any of the embodiments of (1) to (8) above, the system further comprises a second magnetic sensor for measuring a second magnetic field, which is a magnetic field near the current collector of the battery, and a battery type estimation unit for estimating the type of the battery based on the measurement result of the second magnetic field measured by the second magnetic sensor when current is passed through the battery.

[0016] (10): In any embodiment of (1) to (9) above, the battery is further provided with a charge / discharge limiting unit that observes the current density flowing inside the battery based on the measurement result of the first magnetic field and controls the potential applied to the battery in accordance with the change in current density, thereby limiting the charging and discharging of the battery in accordance with the change in current density.

[0017] (11): A vehicle according to one aspect of the present invention comprises a battery mounting section for mounting a battery to the vehicle, a first magnetic sensor arranged along a first direction connecting the current collectors of the battery, a battery diagnostic device as described in any of (1) to (10) above, and a vehicle control unit that controls the operation of the vehicle using the power stored in the battery.

[0018] (12): An energy storage device according to one aspect of the present invention comprises a battery mounting section for mounting a battery, a first magnetic sensor arranged along a first direction connecting the current collectors of the battery, a battery diagnostic device as described in any of (1) to (10) above, and an electrical device for charging and discharging power between the battery and an external device.

[0019] (13): The battery diagnosis method according to one aspect of this invention is such that a computer measures a first magnetic field generated when a current is passed through the battery by a first magnetic sensor arranged along a first direction connecting the current collectors of the battery, and estimates the deterioration state of the battery based on the component of the first magnetic field in the first direction.

[0020] (14): The program according to one aspect of this invention causes a computer to measure a first magnetic field generated when a current is passed through the battery by a first magnetic sensor arranged along a first direction connecting the current collectors of the battery, and estimate the deterioration state of the battery based on the component of the first magnetic field in the first direction.

Advantages of the Invention

[0021] (1)~(14) According to this, a battery diagnosis device measures a first magnetic field generated when a current is passed through the battery by a first magnetic sensor arranged along a first direction connecting the current collectors of the battery, and estimates the deterioration state of the battery based on the component of the first magnetic field in the first direction, whereby the deterioration state of the battery can be appropriately managed.

Brief Description of the Drawings

[0022] [Figure 1] It is a diagram showing an outline of the configuration of a battery cell. [Figure 2] It is a diagram showing an outline of the current collection mechanism of a battery group constituting a battery cell. [Figure 3] It is a diagram showing an outline of the configuration of a wound electrode body. [Figure 4] It is a diagram showing a configuration example of the battery diagnosis device of an embodiment. [Figure 5] It is a diagram showing an outline of the dimensions and shape of a battery cell. [Figure 6] It is a diagram showing an example of how the magnetic field characteristics of a battery cell change with the deterioration of the battery cell. [Figure 7]This diagram explains the factors that may explain the strong correlation between the magnetic field characteristics in the left-right direction and the degree of battery cell degradation. [Figure 8] This flowchart shows an example of the process by which the battery diagnostic device of the embodiment determines the battery type of a battery cell. [Figure 9] This diagram illustrates the magnetic field characteristics near the current collector of a battery cell. [Figure 10] This figure shows an example of measurement results for the magnetic field characteristics near the current collector of a battery cell. [Figure 11] This figure shows an example of an integrated discharge characteristic graph generated based on magnetic field characteristics measured near the current collector. [Figure 12] This figure shows an example of an integrated discharge characteristic graph generated based on the magnetic field characteristics measured near the wound electrode body. [Figure 13] This figure shows an example of the application of the battery diagnostic device according to the embodiment. [Modes for carrying out the invention]

[0023] Hereinafter, embodiments of the battery diagnostic device, vehicle, energy storage device, battery diagnostic method, and program of the present invention will be described with reference to the drawings.

[0024] Figures 1 to 3 show an example of a battery cell in this embodiment. Figure 1 shows an outline of the configuration of the battery cell 200, and Figure 2 shows an outline of the current collection mechanism of the battery group constituting the battery cell 200. Figure 2 shows an example of a battery cell 200 that collects current from two wound electrode bodies 300 (batteries), but the number of batteries that a single battery cell 200 collects current from may be one or three or more. Figure 3 shows an outline of the battery mechanism of the battery cell 200. The battery cell 200 shown in Figure 1 has one or more wound electrode bodies 300 (winding bodies) and an electrolyte (not shown) inside, and is equipped with a positive electrode terminal 210 and a negative electrode terminal 220.

[0025] Furthermore, as shown in Figure 2, the battery cell 200 includes a positive electrode current collector 301A and a negative electrode current collector 301B that collect current from the positive electrode 340 and negative electrode 350 (see Figure 3) of one or more wound electrode bodies 300, respectively. The positive electrode current collector 301A is connected to the positive electrode terminal 210 of the battery cell 200, and the negative electrode current collector 301B is connected to the negative electrode terminal 220 of the battery cell. In this embodiment, the direction connecting the positive electrode current collector 301A and the negative electrode current collector 301B is the longitudinal direction of the battery cell 200. That is, the battery cell 200 in this embodiment is long in the direction connecting the current collectors 301 and short in the depth direction.

[0026] Furthermore, each individual wound electrode body 300 comprises a positive electrode tab 310, a negative electrode tab 320, a separator 330, a positive electrode 340, and a negative electrode 350, as shown in Figure 3. The separator 330 is a component that isolates the positive electrode 340 and the negative electrode 350, holds the electrolyte, and ensures ionic conductivity between the positive electrode 340 and the negative electrode 350. The wound electrode body 300 is constructed by stacking and winding the positive electrode tab 310, the negative electrode tab 320, the separator 330, the positive electrode 340, and the negative electrode 350 in the order shown in Figure 3.

[0027] Figure 4 shows an example configuration of the battery diagnostic device 400 in this embodiment. The battery diagnostic device 400 comprises an internal battery 410, a current output unit 420, a magnetic field characteristic measurement unit 430, a storage unit 440, a control unit 450, an input unit 460, and an output unit 470. Of these components, at least the control unit 450 is realized by a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or GPU (Graphics Processing Unit), or by the cooperation of software and hardware. The program may be stored in advance on a storage device such as an HDD (Hard Disk Drive) or flash memory (a storage device equipped with a non-transient storage medium), or it may be stored on a removable storage medium such as a DVD or CD-ROM (a non-transient storage medium) and installed when the storage medium is inserted into a drive device.

[0028] The internal battery 410 is a battery that supplies the power necessary for the operation of the battery diagnostic device 400. Each functional unit of the battery diagnostic device 400 can be operated by the power supplied by the internal battery 410. The internal battery 410 may be a battery or an interface that obtains power from another power source.

[0029] The current output unit 420 is a current application circuit controlled to apply a specific current to the battery cell 200. The specific current is a current applied to the battery cell 200 for the purpose of identifying the battery type of the battery cell 200 (hereinafter referred to as the "diagnostic current"). The current output unit 420 applies a current of the intensity instructed by the control unit 450 to the target battery cell 200. The current output by the current output unit 420 is applied to the battery cell 200 via the application probe P0.

[0030] The magnetic field characteristic measurement unit 430 is a circuit that measures the magnetic field characteristics of the object to be measured based on probe signals acquired by measurement probes P1 and P2. Measurement probe P1 is a probe for measuring the magnetic field characteristics of the longitudinal surface of the battery cell 200. Measurement probe P2 is a probe for measuring the magnetic field characteristics near the positive electrode current collector 301A and / or the negative electrode current collector 301B of the battery cell 200. Hereinafter, unless otherwise specified, the positive electrode current collector 301A and / or the negative electrode current collector 301B will be referred to as current collector 301. The positions of measurement probes P1 and P2 may be changed by manual operation by the user, or multiple measurement probes P1 and P2 may be arranged in predetermined positions. Note that measurement probe P1 is an example of a "first magnetic sensor", and measurement probe P2 is an example of a "second magnetic sensor". Also, the magnetic field characteristic measurement unit 430 is an example of an "acquisition unit". Furthermore, the magnetic field characteristics measured using the measurement probe P1 are an example of the "first magnetic field," and the magnetic field characteristics measured using the measurement probe P2 are an example of the "second magnetic field."

[0031] The magnetic field characteristic measurement unit 430 measures the magnetic field characteristics of the surface of the battery cell 200 in a state in which a diagnostic current is applied to the battery cell 200, based on the probe signal acquired in that state. More specifically, the magnetic field characteristic measurement unit 430 measures the distribution of the magnetic field characteristics (hereinafter referred to as "first magnetic field characteristics") on the longitudinal side surface (long side) of the battery cell 200 based on a first probe signal acquired by the measurement probe P1. The magnetic field characteristic measurement unit 430 also measures the magnetic field characteristics (hereinafter referred to as "second magnetic field characteristics") near the current collector 301 of the battery cell 200 based on a second probe signal acquired by the measurement probe P2.

[0032] In the battery diagnostic device 400 of this embodiment, the measuring probe P1 is positioned along the longitudinal direction L1 connecting the lowest points in the height direction of the current collector 301. Figure 4 shows an example of the configuration and arrangement of the current collector, where the height of the current collector 301 is approximately half the height of the battery cell 200, and the lowest point of the current collector 301 is positioned approximately at the center in the height direction of the battery cell 200. By configuring or positioning the measuring probe P1 in this way, it becomes possible to measure the magnetic field characteristics of the battery cell 200 more accurately when energized. The length of the current collector 301 in the height direction is arbitrary, and the position of the measuring probe P1 may be changed according to the position of the lowest point of the current collector 301 in the height direction.

[0033] Furthermore, the timing of the magnetic field characteristic measurement unit 430 measuring the first and second magnetic field characteristics is appropriately controlled by the output control unit 451 of the control unit 450 in accordance with the application of the diagnostic current. The magnetic field characteristic measurement unit 430 outputs the measured values ​​of the first and second magnetic field characteristics acquired for the battery cell 200 to the control unit 450.

[0034] The storage unit 440 is configured using, for example, a magnetic storage device such as an HDD (Hard Disk Drive) or a semiconductor storage device such as an SSD (Solid State Drive). The storage unit 440 stores various information related to the operation of the battery diagnostic device 400. For example, the storage unit 440 stores data on the magnetic field characteristics measured for the battery cell 200, information such as various attributes of the battery cell 200 estimated based on that data, as well as setting information related to the diagnostic current and data for various programs that implement the control unit 450. The storage unit 440 also pre-stores a correspondence information table 441 as an example of correspondence information, which will be described later.

[0035] The control unit 450 controls various parts of the battery diagnostic device 400 to perform tasks such as measuring the magnetic field characteristics of the battery cells 200, estimating the degree of degradation, estimating the battery type, individual identification, and controlling charging and discharging during use. Specifically, the control unit 450 includes an output control unit 451, a degradation estimation unit 452, a battery type estimation unit 453, a battery identification unit 454, and a charge / discharge limiting unit 455.

[0036] The output control unit 451 has the function of controlling the current output unit 420 to apply a diagnostic current to the battery cell 200. For example, the output control unit 451 can apply a sinusoidal alternating current to the battery cell 200 by continuously changing the output intensity of the diagnostic current. Alternatively, the output control unit 451 can apply a square wave-shaped direct current to the battery cell 200 by changing the output intensity of the diagnostic current at predetermined timings.

[0037] The output control unit 451 may be configured to detect when the battery cell 200 is connected to the battery diagnostic device 400 and to start applying a diagnostic current to the battery cell 200. Alternatively, the output control unit 451 may be configured to start applying a diagnostic current in response to user input.

[0038] The degradation estimation unit 452 estimates the degree of degradation of the battery cell 200 based on the measurement results of the first magnetic field characteristics. More specifically, the degradation estimation unit 452 estimates the degree of degradation of the battery cell 200 based on the distribution of the first magnetic field characteristics in the longitudinal direction of the battery cell 200. Details of the degradation estimation method will be described later. Note that the degradation estimation unit 452 is an example of a "battery state estimation unit".

[0039] The battery type estimation unit 453 estimates the battery type of the battery cell 200 based on the measurement results of the second magnetic field characteristics. Specifically, the battery type estimation unit 453 determines the battery type of the battery cell 200 to be estimated based on correspondence information that associates the battery type with the measurement results (or values ​​obtained based on the measurement results) of the second magnetic field characteristics measured for each battery cell 200 of each battery type. In this embodiment, the correspondence information is assumed to be stored in the storage unit 440 in advance as a correspondence information table 441. The battery type estimation unit 453 outputs the estimated battery type information for the battery cell 200 to the output unit 470.

[0040] The battery identification unit 454 performs individual identification of the battery cells 200 based on the measurement results of either the first or second magnetic field characteristics. More specifically, the battery identification unit 454 estimates the state change of the battery cell 200 based on the measurement results of the first magnetic field characteristics and detects the state change of the battery cell 200 by managing the estimation results along with their history. In addition, the battery identification unit 454 detects the replacement of the battery cell 200 based on the measurement results of the second magnetic field characteristics. By detecting such state changes and replacements, the battery identification unit 454 can identify individual battery cells 200. Note that this is an example of the battery identification unit 454 "battery state estimation unit".

[0041] The charge / discharge limiting unit 455 limits the charging and discharging of the battery cell 200 during use according to the degradation state of the battery cell 200. The criteria for whether or not to limit charging and discharging by the charge / discharge limiting unit 455 can be arbitrarily determined. For example, the charge / discharge limiting unit 455 may control the discharge amount of the battery cell 200 by controlling the load connected to the battery cell 200. For example, the charge / discharge limiting unit 455 may control the charge amount of the battery cell 200 by controlling the battery cell 200 or a charging unit (not shown) that charges the battery cell 200 to create a charging prohibition period.

[0042] Furthermore, the charge / discharge limiting unit 455 may record charge / discharge control information for limiting the amount of charge / discharge during use in the storage unit (not shown) of the battery cell 200. In this case, the function to control the amount of charge / discharge of the battery cell 200 based on the charge / discharge control information recorded in the storage unit of the battery cell 200 may be provided on the side of the equipment (for example, an electric vehicle) that uses the battery cell 200.

[0043] The input unit 460 has the function of inputting information related to the operation of the battery diagnostic device 400. For example, the input unit 460 may be equipped with an input device such as a mouse or keyboard, and may be configured to input the necessary information via these input devices. Alternatively, the input unit 460 may be equipped with a wired or wireless communication interface, and may be configured to input the necessary information via these communication interfaces. The input unit 460 outputs the input information to the control unit 450.

[0044] The output unit 470 outputs the determination result information output from the battery type estimation unit 453 in a predetermined manner. For example, the output unit 470 may be equipped with a display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display, and the determination result information may be displayed on these display devices. Alternatively, the output unit 470 may be equipped with a wired or wireless communication interface, and the determination result information may be transmitted to other communication devices via these communication interfaces. Furthermore, the output unit 470 may be equipped with an audio output device such as a speaker, and audio indicating the content of the determination result information may be output to the audio output device.

[0045] Figures 5 to 7 illustrate how the degradation estimation unit 452 estimates the degradation state of the battery cell 200 in the battery diagnostic device 400 of this embodiment. Figure 5 is a diagram showing the schematic dimensions and shape of a hypothetical battery cell 200. Here, a battery cell 200A is assumed in which the positive terminal 210 and the negative terminal 220 are arranged in the longitudinal direction. In Figure 5, the longitudinal direction of the battery cell 200A is the z-axis direction, and a battery cell 200A is assumed in which the depth (x-axis direction) is shorter than the width (z-axis direction) and height (y-axis direction). In Figure 5, points A, B, and C show examples of the placement positions of magnetic sensors that are placed to measure the magnetic field characteristics of the surface of the battery cell 200A. For example, points A, B, and C are points in the z-axis direction that correspond to 1 / 4, 1 / 2, and 3 / 4 of the width of the battery cell 200A, respectively, with the left end of the battery cell 200A as the reference point, and points in the y-axis direction that correspond to 1 / 2 of the height of the battery cell 200A. Thus, when measuring the distribution of the first magnetic field characteristics in the longitudinal direction of the battery cell 200, it is preferable to place magnetic sensors at at least three points: the center of the line segment connecting the current collectors 301 (for example, point B) and points closer to each current collector 301 than the center (for example, points A and C).

[0046] Figure 6 shows an example of how the magnetic field characteristics at points A, B, and C change as the battery cell 200 deteriorates. The horizontal axis of Figure 6 represents the measurement locations of the magnetic field characteristics, and the vertical axis shows the measured values ​​of the magnetic field characteristics at each measurement location. More specifically, the vertical axis represents the difference between the magnetic field strength when the SOC is 85% and the magnetic field strength when the SOC is 15%. That is, a bar graph with a positive value indicates that the magnetic field strength at SOC 15% is stronger than the magnetic field strength at SOC 85%, and a bar graph with a negative value indicates that the magnetic field strength at SOC 15% is weaker than the magnetic field strength at SOC 85%. The Ax, Ay, and Az on the horizontal axis represent the x-axis, y-axis, and z-axis components of the magnetic field characteristics measured at point A. Similarly, Bx, By, and Bz on the horizontal axis represent the x-axis, y-axis, and z-axis components of the magnetic field characteristics measured at point B, while Cx, Cy, and Cz represent the x-axis, y-axis, and z-axis components of the magnetic field characteristics measured at point C.

[0047] Furthermore, the three data series #1, #2, and #3 at each measurement location represent the degree of degradation of the battery cell 200. Specifically, data series #1 represents the measured values ​​for a battery cell 200 in a state of zero degradation. A battery cell 200 with zero degradation is equivalent to a battery cell 200 in a brand-new state (hereinafter referred to as the "initial state"), and can be said to be a battery cell 200 with a capacity retention rate of 100%. Data series #2 represents the measured values ​​for a battery cell 200 that has degraded to a certain extent from the state of zero degradation (hereinafter referred to as the "first degradation state"). For example, Figure 6 shows a data series for a battery cell 200 with a capacity retention rate of 88% as an example of a battery cell 200 in the first degradation state. For example, a battery cell 200 with a capacity retention rate of 88% may correspond to one that has been on the market for 5 to 6 years. Furthermore, data series #3 represents the measured values ​​for battery cell 200 in a state where the expected lifespan has ended (hereinafter referred to as "second degradation state"). For example, Figure 6 shows a data series for battery cell 200 with a capacity retention rate of 60% as an example of a battery cell in the second degradation state.

[0048] As can be seen in Figure 6, regarding the state transitions of battery cell 200 from its initial state to the first and second degradation states, the magnetic field component in the left-right direction shows a decrease in current density as the battery cell 200 degrades (corresponding to the decrease in the magnetic field difference on the vertical axis), indicating a tendency for the degree of degradation to be proportional to the decrease in current density. On the other hand, the magnetic field components in the depth and vertical directions show a tendency for current to be rerouted in the vertical and depth directions due to the effect of the decrease in current density in the left-right direction. Thus, it was found that there is a strong correlation between the degree of degradation of battery cell 200 and the magnetic field characteristics of the surface of battery cell 200, particularly in the measured values ​​in the left-right direction.

[0049] Figure 7 illustrates the factors that may explain the strong correlation between the magnetic field characteristics in the left-right direction and the degree of degradation of the battery cell 200. More specifically, Figure 7 shows the current flowing when power is applied to battery cell 200A in each degradation state. In Figure 7, battery cell 200A-1 represents battery cell 200A in its initial state. In battery cell 200A-1 in its initial state, there is no high-resistance region that obstructs the flow of current, so the current passes through the area near the center where the resistance is low between the positive and negative current collectors 301.

[0050] Next, battery cell 200A-2 represents battery cell 200A in a state where polarization occurs in response to an increase in the amount of current flowing, and a first high-resistance region is created due to the resulting polarization, causing the resistance to rise. For example, in the example in Figure 7, the first high-resistance region is formed in the center of the height direction of battery cell 200A. In battery cell 200A-2 in this state, the current flows between each current collector 301 in a path that bypasses the first high-resistance region and goes to the low-resistance region (fresh region).

[0051] Next, battery cell 200A-3 represents battery cell 200A in a state where polarization progresses further in response to a further increase in the amount of current flowing, resulting in the formation of a second high-resistance region where the resistance is even higher than the first high-resistance region. For example, the second high-resistance region is known to be caused by the growth of SEI or cracking of the active material. For example, in the example in Figure 7, deterioration has progressed in parts other than the center between each current collector 301, and a state in which multiple second high-resistance regions have been formed is shown. In battery cell 200A-3 in this state, current flows between each current collector 301 by passing through the first high-resistance region, which has lower resistance than the second high-resistance region.

[0052] Next, battery cell 200A-4 represents battery cell 200A in a state where polarization progresses further in response to a further increase in the amount of current flowing, and the second high-resistance region is further expanded. For example, in the example in Figure 7, the second high-resistance region is formed over a wider area than in the case of battery cell 200A-3, and the degree of freedom of the detour paths that the current can take has decreased. As a result, although the amount of detour is smaller than in the case of battery cell 200A-2, the current flows through a longer path than in the case of battery cell 200A-3.

[0053] Thus, the change in magnetic field characteristics is thought to be caused by a change in the way current flows as the battery cell 200 deteriorates, and it is thought that how a high-resistance region is formed inside the battery cell 200 differs from one battery cell to another. The applicant of this application has found that a more pronounced deterioration trend is shown in the distribution of magnetic field characteristics in the left-right direction of the battery cell 200A, and has configured the battery diagnostic device 400 of the embodiment so that the deterioration trend can be estimated from the magnetic field characteristics of the battery cell 200A in the left-right direction.

[0054] Figure 8 is a flowchart illustrating an example of the process by which the battery diagnostic device 400 of this embodiment determines the battery type of the battery cell 200. Here, it is assumed that at the start of the flowchart, the battery diagnostic device 400 is connected to the battery cell 200 to be determined. First, the battery diagnostic device 400 receives an input via the input unit 460 to apply a diagnostic current to the battery cell 200. In response to this input, the output control unit 451 controls the current output unit 420 to apply a diagnostic current to the battery cell 200 (step S101).

[0055] Next, probe P2 outputs a probe signal corresponding to the magnetic field characteristics near the current collector 301 (step S102). Probe P2 can be a coil sensor, reed sensor, Hall element, MR (Magneto Resistive) sensor, MI (Magneto Impedance) sensor, etc. For example, probe P2 outputs a probe signal indicating the current value induced by the magnetic field, and the magnetic field characteristic measurement unit 430 measures the magnetic field characteristics by calculating the magnetic field component based on the current value indicated by the probe signal (step S103).

[0056] Next, the battery type estimation unit 453 determines whether the battery cell 200 is a legitimate battery cell based on the magnetic field characteristic measurement results from the magnetic field characteristic measurement unit 430. Specifically, the battery type estimation unit 453 determines whether the measured magnetic field component is within the allowable error range relative to the previous measurement value, or within a predetermined specified range (step S104). The battery type estimation unit 453 determines that the battery cell 200 is a legitimate battery cell if the measured value of the magnetic field component falls within either range, and determines that the battery cell 200 is not a legitimate battery cell if it does not fall within either range.

[0057] If the battery cell 200 in question is determined to be a legitimate battery cell, the battery type estimation unit 453 executes normal processing (step S105). Normal processing includes processes to make the battery cell 200 usable and processes using the battery cell 200. On the other hand, if the battery cell 200 in question is determined to be not a legitimate battery cell in step S104, the battery type estimation unit 453 executes abnormal processing (step S106). Abnormal processing may include processes to disable the battery cell 200, processes to notify that the battery cell 200 is not a legitimate battery cell, and processes to perform actions such as issuing warnings regarding the use of the battery cell 200.

[0058] The normal operation can be any operation that should be performed when the target battery cell 200 is a legitimate battery cell. Similarly, the abnormal operation can be any operation that should be performed when the target battery cell 200 is not a legitimate battery cell. For example, the battery type estimation unit 453 may perform an operation that enables the vehicle equipped with the target battery cell 200 to perform its intended function as the normal operation, and an operation that limits the performance that the vehicle can perform as the abnormal operation. With such control, it is possible to prevent the vehicle from being put at risk by limiting the performance that the vehicle can perform when a non-genuine battery cell is used in a vehicle manufactured by the company.

[0059] Furthermore, for example, the battery type estimation unit 453 may, as a normal operation, execute a process to instruct the system that manages the warranty for the vehicle equipped with the target battery cell 200 to maintain the warranty for the target vehicle, or it may execute a process to instruct the system to suspend the warranty for the target vehicle as an abnormal operation. Such control can prevent the vehicle manufacturer from being burdened with unfair costs due to warranties for accidents, etc., that occur in vehicles that do not use genuine battery cells.

[0060] Furthermore, for example, the battery type estimation unit 453 may, as a normal operation, instruct the system that analyzes vehicle data collected by telematics to provide various services to include vehicles equipped with the target battery cell 200 in the statistical processing, or it may, as an abnormal operation, instruct the system to exclude the target vehicles from the statistical processing. Such control can suppress a decrease in the reliability of statistical processing due to data from vehicles that do not use genuine battery cells, and thus suppress a decline in the quality of service provision.

[0061] Furthermore, this determination of the battery type, and the normal or abnormal processing according to the determination result, may be performed when inspecting the vehicle equipped with the target battery cell 200, or when starting the vehicle equipped with the target battery cell 200, etc.

[0062] Figures 9 and 10 show an example of measurement results of the magnetic field characteristics near the current collector 301 of a battery cell 200 by the battery diagnostic device 400 of this embodiment. Figure 9 shows a schematic of the magnetic field generated by the application of a measurement current, and Figure 10 shows the measurement results. In Figure 9, the dashed arrows represent the flow of the diagnostic current. The diagnostic current flows from the positive terminal 210 through the positive current collector 301A to the wound electrode body 300, through the wound electrode body 300 to the negative current collector 301B, and from the negative current collector 301B to the negative terminal 220. At this time, according to the right-hand rule, a magnetic field is generated in the circumferential direction with the direction of the diagnostic current as the axis.

[0063] In this case, as shown in Figure 10, it was found that a characteristic magnetic field characteristic MD1 is formed near the straight line L1 connecting the lower end of the positive electrode current collector 301A and the lower end of the negative electrode current collector 301B of the battery cell 200. Furthermore, it was found that such a magnetic field characteristic exhibits a distribution corresponding to the physical characteristics of the battery mechanism. That is, if the locations exhibiting characteristic magnetic field characteristics (hereinafter referred to as "characteristic points") are known in advance, the battery diagnostic device 400 only needs to measure the magnetic field at least at such characteristic points, and does not necessarily need to measure the magnetic field over the entire surface of the battery cell 200. For example, if a straight line L1 as shown in the figure is assumed in advance, the battery diagnostic device 400 may measure the magnetic field at three points, A, B, and C, in order to grasp the distribution of magnetic field characteristics along the straight line L1. In Figure 10, for illustrative purposes, the magnetic field strength is classified into four stages, but in reality, the magnetic field strength changes gradually between each stage.

[0064] The magnetic sensor (corresponding to probe P2) used to measure the magnetic field characteristics for determining the battery type may be pre-installed at a position corresponding to a characteristic point of the battery cell 200, or it may be installed at the time of measurement by manual operation by the user. The magnetic sensor may also be installed on the battery cell 200 side, or on the side of the vehicle to which the battery cell 200 is installed. The battery diagnostic device 400 of this embodiment acquires the magnetic field characteristics corresponding to such physical characteristics in advance and determines the battery type of the battery cell 200 by comparing them with the magnetic field characteristics measured for the battery cell 200. Furthermore, considering the possibility of damage to the battery cell 200 or the magnetic sensor, it is preferable that the magnetic sensor can measure the magnetic field without contact with the object being measured (for example, within 1 cm).

[0065] Figures 11 and 12 illustrate an example of how the battery diagnostic device 400 determines whether a target battery cell 200 is genuine or not based on the measurement results of its magnetic field characteristics. The graphs shown in Figures 11 and 12 have the cumulative discharge time of the target battery cell 200 on the horizontal axis and the value obtained by dividing the cumulative current amount [Ah] of the target battery cell 200 by the current value [Ah / I] on the vertical axis. For example, the vertical axis is a value obtained by converting the measured value of the magnetic field generated by the current [G] back into a current value and integrating it (cumulative current [Ah]). The battery diagnostic device 400 can generate the graphs in Figures 11 and 12 by calculating the current value flowing through the battery cell 200 for each time period based on the measured value of the magnetic field characteristics and integrating the calculated current values ​​in a time series. Hereinafter, the graph generated in this way will be referred to as the "cumulative discharge characteristic graph".

[0066] Figure 11 shows an example of an integrated discharge characteristic graph generated based on magnetic field characteristics measured near the current collector 301. As can be seen in Figure 11, the relationship between the integrated current and the integrated discharge time is obtained in a more linear form based on the magnetic field characteristics measured near the current collector 301. Therefore, by storing the information on the magnetic field characteristics measured for the target battery cell 200 in the battery diagnostic device 400, the battery type estimation unit 453 can generate an integrated discharge characteristic graph as needed based on the stored information and determine whether the target battery cell 200 is a genuine product by examining the change in its slope. Note that the replacement timing t1 in Figure 11 is the timing when the genuine battery cell 200 is replaced with another battery cell.

[0067] For example, in the example in Figure 11, if lines L21 and L22 are obtained from the magnetic field characteristics, the battery type estimation unit 453 can determine that the replaced battery cell 200 is genuine because the slope of the lines has not changed before and after the replacement timing t1 (or the amount of change in the slope is less than the threshold). On the other hand, in the example in Figure 11, if lines L21 and L23 are obtained from the magnetic field characteristics, the battery type estimation unit 453 can determine that the replaced battery cell 200 is not genuine because the slope of the lines has changed before and after the replacement timing t1 (or the amount of change in the slope is greater than or equal to the threshold). This method of determining the battery type is based on the applicant's finding that the cumulative discharge characteristics near the current collector 301 do not change significantly unless the battery cell 200 is replaced with a different type of battery cell (for example, a non-genuine battery cell). In other words, in the example in Figure 11, if the battery cell 200 is not replaced at the replacement timing t1, the slope of line L21 will be maintained regardless of the degree of deterioration.

[0068] Figure 12 shows an example of an integrated discharge characteristic graph generated based on magnetic field characteristics measured near the wound electrode body 300 (for example, points A, B, and C). According to the magnetic field characteristics measured near the wound electrode body 300, the relationship between the integrated current and the cumulative discharge time tends to follow a curve as shown in the figure. In such cases, the charge / discharge limiting unit 455 can detect a change in the state of the target battery cell 200 (including replacement) by checking the continuity of the slope of the obtained curve. The change in state here refers to a change in the integrated discharge characteristics, which is caused by changes in the degree of degradation of the battery cell 200 or changes in how it is used. The charge / discharge limiting unit 455 limits the charging and discharging of the battery cell 200 according to the detected change in state. In Figure 12, the replacement timing t2 is the timing when the genuine battery cell 200 is replaced with another battery cell 200. The dashed curve represents the change in integrated discharge characteristics when the battery cell 200 is not replaced at the replacement timing t2.

[0069] For example, in the example in Figure 12, if curves L31 and L32 are obtained from the magnetic field characteristics, or if curves L41 and L42 are obtained, the charge / discharge limiting unit 455 can recognize that no abrupt state changes due to replacement or the like have occurred in the battery cell 200, since the slope of the curves is continuous throughout the entire period. Furthermore, since curve L32 has an inflection point P1, the charge / discharge limiting unit 455 can detect that a gradual state change has occurred (timing t3) in the battery cell 200 indicated by curves L31 and L32 due to continuous use or a change in usage.

[0070] In contrast, in the example in Figure 12, if curves L31 and L33 are obtained from the magnetic field characteristics, or if curves L41 and L43 are obtained, the charge / discharge limiting unit 455 can recognize that a rapid change in state (replacement of the battery cell 200) has occurred before and after the replacement timing t2 because the gradient of the straight line is discontinuous before and after the replacement timing t2 (or the amount of change in the gradient is greater than or equal to a threshold). Furthermore, since curve L43 has an inflection point P2, the charge / discharge limiting unit 455 can detect that a gradual change in state has occurred (timing t4) for the replaced battery cell 200 shown by curve L43 due to continuous use or a change in usage.

[0071] When battery cell 200 is replaced with another battery cell, the current path flowing through the battery cell changes, resulting in a change in current density. In such cases, the charge / discharge limiting unit 455 can limit the charging and discharging of battery cell 200 in accordance with the change in state of battery cell 200 by managing the potential applied to battery cell 200 in accordance with the observed change in current density.

[0072] Furthermore, the battery identification unit 454 performs individual identification of the battery cell 200 based on information indicating the cumulative discharge characteristics of the battery cell 200 (hereinafter referred to as "characteristic information"). As described above, the cumulative discharge characteristics make it possible to identify whether or not there has been a change in the state of the battery cell 200. Changes in the state of the battery cell 200 include sudden changes due to replacement, etc., and gradual changes due to continuous use or changes in usage. Since the content of such changes in state differs depending on the individual usage of the battery cell 200, the history information showing the history can be used as individual identification information that enables individual identification of each battery cell 200. Therefore, the battery diagnostic device 400 of this embodiment is configured to record the history information acquired by the battery identification unit 454 for each battery cell 200 on the device side and on the battery cell 200 side, and to perform individual identification of each battery cell 200 by comparing them as necessary. If each battery cell 200 has a storage unit, the history information may be recorded in the storage unit of each battery cell 200. Furthermore, if a battery device composed of one or more battery cells 200 has a storage unit, the battery device may record the history information of each battery cell 200 in association with the identification information of each battery cell 200 in the storage unit.

[0073] As explained in Figures 11 and 12, the battery diagnostic device 400 of the embodiment can measure the magnetic field characteristics of the battery cell 200 and estimate the degradation state of the battery cell 200 based on the measurement results. Furthermore, the battery diagnostic device 400 can acquire the cumulative discharge characteristics based on the measurement results of the magnetic field characteristics, estimate the battery type based on the acquired cumulative discharge characteristics, detect changes in the state of the battery cell 200, and limit the charging and discharging of the battery cell 200 during use according to the degradation state of the battery cell 200. In addition, the battery diagnostic device 400 can identify each individual battery cell 200 by recording and accumulating characteristic information showing the history of the cumulative discharge characteristics.

[0074] Figure 13 shows an example of the application of the battery diagnostic device 400 of the embodiment. Figure 13 shows a vehicle M equipped with the battery diagnostic device 400 as an example of the application of the battery diagnostic device 400. Although the vehicle M in Figure 13 is assumed to be a four-wheel drive passenger car, the vehicle equipped with the battery diagnostic device 400 can be any other vehicle that uses a battery cell 200 or a battery device 100 which integrates battery cells 200 as a power source. The vehicle M comprises a vehicle control unit M1 which controls various parts of the vehicle, a battery mounting unit M2 for mounting the battery cell 200 to the vehicle M, and a battery diagnostic device 400 which determines the battery type of the battery cell 200 mounted on the vehicle.

[0075] In this case, for example, the battery diagnostic device 400 determines the battery type of the battery cell 200 installed in the vehicle M and performs normal or abnormal processing according to the determination result. For example, if the battery diagnostic device 400 determines that the battery cell 200 installed in the vehicle M is genuine, it may perform normal processing by granting permission to the vehicle control unit M1 to drive the vehicle M. Conversely, for example, if the battery diagnostic device 400 determines that the battery cell 200 installed in the vehicle M is not genuine, it may perform abnormal processing by instructing the vehicle control unit M1 not to drive the vehicle M.

[0076] Furthermore, for example, the battery diagnostic device 400 may be configured to detect changes in the battery by measuring and recording the magnetic field characteristics of the vehicle M when the engine is off (an example of when the power is off) using the magnetic field characteristic measuring unit 430 as the previous magnetic field characteristics, and then measuring the current magnetic field characteristics when the engine is turned on next (an example of when the power is on), and comparing the previous magnetic field characteristics with the current magnetic field characteristics. Note that vehicle M is an example of a "mobile body".

[0077] Furthermore, for example, the battery diagnostic device 400 may limit the discharge amount of the battery cell 200 to not exceed the allowable amount by activating the brakes of the vehicle M. Also, for example, the battery diagnostic device 400 may limit the charge amount of the battery cell 200 by regenerative power to not exceed the allowable amount by activating the brakes of the vehicle M.

[0078] Note that Figure 13 does not limit the application of the battery diagnostic device 400 of the embodiment to vehicles. The battery diagnostic device 400 of the embodiment may be applied to an energy storage device equipped with the battery cell 200 of the embodiment and any electrical equipment that charges and discharges power between the mounted battery cell 200 and external equipment. For example, the electrical equipment may be a power conversion device such as an inverter or a converter. Also, for example, the energy storage device may be a standalone power supply, a charger, a grid power supply, etc.

[0079] The embodiments described above can be expressed as follows. A storage medium that stores computer-readable instructions, A processor connected to the storage medium, The processor executes the computer-readable instructions to: A first magnetic sensor, positioned along a first direction connecting the current collectors of the battery, measures the first magnetic field generated when current is passed through the battery. The degradation state of the battery is estimated based on the first directional component of the first magnetic field. Battery diagnostic device.

[0080] In describing the embodiments of the battery diagnostic device, vehicle, electrical equipment, battery diagnostic method, and program of the present invention, the case where the object of diagnosis is a battery cell has been described above. However, the object of diagnosis may also be a battery device that integrates battery cells. When the object of diagnosis is a battery device, the current collection structure of the battery cell 200 in the above description may be read as the current collection structure of the battery device. In this case, the structure (shape, dimensions, arrangement, etc.) of the positive terminal 210, negative terminal 220, current collector 301, etc. of the battery cell 200 may be modified so that each battery cell 200 can collect current at the longitudinal end of the battery device. Furthermore, although a prismatic cell was exemplified as the battery cell 200 in the above embodiment, this is just an example, and the shape of the battery cell 200 is not limited to a prismatic cell. For example, the battery cell 200 of the embodiment may be applied to laminate cells, cylindrical cells, etc., as long as the current collection structure of the electrodes is similar.

[0081] Although embodiments for carrying out the present invention have been described above using examples, the present invention is not limited in any way to these embodiments, and various modifications and substitutions can be made without departing from the spirit of the present invention. [Explanation of Symbols]

[0082] 100...Battery device, 200...Battery cell, 210...Positive terminal, 220...Negative terminal, 300...Wound electrode body, 301...Current collector, 301A...Positive current collector, 301B...Negative current collector, 310...Positive tab, 320...Negative tab, 330...Separator, 340...Positive electrode, 350...Negative electrode, 400...Battery diagnostic device, 410...Internal battery, 420...Current output unit, 430...Magnetic field characteristic measurement unit, 440...Storage unit, 441...Corresponding information table, 450...Control unit, 451...Output control unit, 452...Degradation estimation unit, 453...Battery type estimation unit, 454...Battery identification unit, 455...Charge / discharge limiting unit, 460...Input unit, 470...Output unit

Claims

1. An acquisition unit that acquires a measurement value of the first magnetic field generated when current is passed through the battery, using a plurality of first magnetic sensors arranged along a first direction connecting the current collectors of the battery, A battery state estimation unit that estimates the degradation state of the battery based on the component of the first magnetic field in the first direction, Equipped with, The first magnetic sensor is positioned along a straight line connecting the lower ends of the current collectors, Battery diagnostic device.

2. An acquisition unit that acquires a measurement value of a first magnetic field generated when current is passed through the battery, using a plurality of first magnetic sensors arranged along a first direction connecting the current collectors of the battery, A battery state estimation unit that estimates the degradation state of the battery based on the component of the first magnetic field in the first direction, Equipped with, The battery state estimation unit estimates that the battery is more degraded the smaller the decrease in the first-direction component of the first magnetic field in the measured value from the first-direction component of the first magnetic field in the initial state of the battery. Battery diagnostic device.

3. An acquisition unit that acquires a measurement value of a first magnetic field generated when current is passed through the battery, using a plurality of first magnetic sensors arranged along a first direction connecting the current collectors of the battery, A battery state estimation unit that estimates the degradation state of the battery based on the component of the first magnetic field in the first direction, Equipped with, The battery further comprises a second magnetic sensor for measuring a second magnetic field, which is a magnetic field near the current collector of the battery. The system further includes a battery type estimation unit that estimates the type of the battery based on the measurement result of the second magnetic field measured by the second magnetic sensor when current is supplied to the battery. Battery diagnostic device.

4. The first magnetic sensor is positioned corresponding to the long side of the battery. A battery diagnostic device according to any one of claims 1 to 3.

5. The battery state estimation unit detects that the battery has been replaced with another battery based on the change in the slope of the curve showing the cumulative current amount with respect to the discharge time of the battery. The battery diagnostic device according to claim 2.

6. The battery further comprises a second magnetic sensor for measuring a second magnetic field, which is a magnetic field near the current collector of the battery. The battery state estimation unit detects changes in the state related to the deterioration of the battery based on the measurement results of the second magnetic field, which is measured by the second magnetic sensor when current is supplied to the battery. A battery diagnostic device according to any one of claims 1 to 5.

7. The battery state estimation unit detects changes in the state related to the degradation of the battery based on the amount of change in the slope of the curve showing the amount of accumulated current with respect to the discharge time of the battery. The battery diagnostic device according to claim 6.

8. The system further includes a battery identification unit that identifies individual batteries based on a history of changes in the state related to the degradation of the aforementioned batteries. The battery diagnostic device according to claim 6 or 7.

9. The system further includes a charge / discharge limiting unit that observes the current density flowing inside the battery based on the measurement results of the first magnetic field, and controls the potential applied to the battery in accordance with the change in current density, thereby limiting the charging and discharging of the battery in accordance with the change in current density. A battery diagnostic device according to any one of claims 1 to 8.

10. A battery mounting section for installing the battery in the vehicle, A first magnetic sensor is arranged along a first direction connecting the current collectors of the battery, A battery diagnostic device according to any one of claims 1 to 9, A vehicle control unit that controls the operation of the vehicle using the power stored in the battery, A vehicle equipped with the following features.

11. A battery mounting section where the battery is installed, A first magnetic sensor is arranged along a first direction connecting the current collectors of the battery, A battery diagnostic device according to any one of claims 1 to 9, An electrical device that charges and discharges power between the battery and an external device, A power storage device equipped with the following features.

12. Computers Multiple first magnetic sensors arranged along a first direction connecting the current collectors of the battery measure the first magnetic field generated when current is passed through the battery. The degradation state of the battery is estimated based on the component of the first magnetic field in the first direction. A battery diagnostic method, The first magnetic sensor is positioned along a straight line connecting the lower ends of the current collectors, Battery diagnostic methods.

13. On the computer, Multiple first magnetic sensors arranged along a first direction connecting the current collectors of the battery measure the first magnetic field generated when current is passed through the battery. The degradation state of the battery is estimated based on the component of the first magnetic field in the first direction. It is a program for that purpose, The first magnetic sensor is positioned along a straight line connecting the lower ends of the current collectors, program.

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