Devices, assay devices, methods, and assay methods

Abstract

The measuring device (1) is a device for detecting voltage changes in the energy storage device (10). It supplies a constant current to the energy storage device (10) and measures the voltage associated with the energy storage device (10) supplied with a constant voltage. The measuring device (1) then obtains the voltage changes of the energy storage device (10) based on the electrical characteristics that serve as a reference for the energy storage device (10).

Description

Technical Field

[0001] This invention relates to an apparatus, measuring device, method, and measuring method for detecting voltage changes in energy storage devices. Background Technology

[0002] JP2015-072148A discloses an inspection method for determining the quality of a secondary battery based on the amount of voltage drop during aging. In this inspection method, the secondary battery is stored for several days to several weeks with the positive and negative terminals open. After the voltage drops due to self-discharge, the voltage is measured, thereby estimating the internal state of the secondary battery. Summary of the Invention

[0003] The inspection method in JP2015-072148A requires storing the secondary battery for several days to several weeks as an aging period until the voltage drops due to self-discharge. Therefore, it is difficult to obtain the status of the energy storage device in a short period of time.

[0004] The present invention was made in view of the above-mentioned problems, and its purpose is to obtain the status of the energy storage device in a short time.

[0005] According to one aspect of the present invention, an apparatus for detecting voltage changes in a storage device includes: a constant current supply unit for supplying a constant current to the storage device; a voltage measuring unit for measuring the voltage associated with the storage device to which the constant current is supplied; and a detection unit for detecting the measured voltage change of the storage device. The measuring apparatus acquires the voltage change of the storage device based on electrical characteristics that serve as a reference for the storage device.

[0006] According to this scheme, by supplying a constant current to the energy storage device, the voltage change of the energy storage device, which is correlated with its internal state, becomes larger. In this case, the voltage change of the energy storage device is detected based on its electrical characteristics, which serve as a reference for the energy storage device, thereby enabling high-precision acquisition of the voltage change. This allows for the acquisition of the energy storage device's state in a short time. Attached Figure Description

[0007] Figure 1 This is a diagram showing the configuration of the measuring device for the energy storage device according to the first embodiment.

[0008] Figure 2 This is a flowchart illustrating a measurement method for an energy storage device using the measuring apparatus of the first embodiment.

[0009] Figure 3 This is a flowchart illustrating an example of the state computation processing included in a measurement method.

[0010] Figure 4This is a graph illustrating an example of the change in the potential difference between the voltage of the energy storage device and the reference voltage relative to the charging time of the energy storage device.

[0011] Figure 5 This is a graph showing a comparative example of voltage changes in a storage device relative to its charging time.

[0012] Figure 6 This is a diagram showing the configuration of the measuring device for the energy storage device according to the second embodiment.

[0013] Figure 7 This is a flowchart illustrating the state operation processing of the third embodiment.

[0014] Figure 8 This is a diagram showing the configuration of the measuring device for the energy storage device according to the fourth embodiment.

[0015] Figure 9 This is a flowchart illustrating a measurement method for an energy storage device using the measuring apparatus of the fourth embodiment.

[0016] Figure 10 This is a flowchart illustrating an example of the voltage determination process included in the measurement method.

[0017] Figure 11 This is a diagram illustrating an example of voltage changes in an energy storage device caused by charging and discharging.

[0018] Figure 12 This is a graph illustrating the relationship between the voltage of an energy storage device and the electrostatic capacitance component of the device.

[0019] Figure 13 This is a flowchart illustrating an example of the state computation processing included in a measurement method.

[0020] Figure 14 This is a graph illustrating an example of voltage variation in an energy storage device relative to the constant current supply time.

[0021] Figure 15 It means as Figure 14 A comparative example is shown in the figure, illustrating the voltage change of the energy storage device relative to the constant current supply time when the electrostatic capacitance component of the energy storage device is at its maximum.

[0022] Figure 16 This is a flowchart illustrating the state operation processing of the fifth embodiment.

[0023] Figure 17 This is a diagram showing the configuration of the measuring device for the energy storage device according to the sixth embodiment.

[0024] Figure 18This is a diagram showing the configuration of the measuring device for the energy storage device according to the seventh embodiment.

[0025] Figure 19 This is a block diagram illustrating the functional configuration of the controllers included in the measuring device.

[0026] Figure 20 This is a flowchart illustrating the measurement method for an energy storage device using the measuring apparatus of the seventh embodiment.

[0027] Figure 21 This is a diagram illustrating an example of voltage fluctuations in an energy storage device after normal discharge.

[0028] Figure 22 It is Figure 21 The diagram shown is an enlarged representation of the increase in open-circuit voltage of the energy storage device.

[0029] Figure 23 This is a flowchart illustrating an example of the state computation processing included in a measurement method.

[0030] Figure 24 The graph illustrates the changes in the measured voltage of the energy storage device during constant current charging, the changes in the open-circuit voltage of the energy storage device before constant current charging, and the changes in the measured voltage after correction.

[0031] Figure 25 This is a graph showing an example of the corrected voltage change relative to the charging time of the energy storage device.

[0032] Figure 26 This is a flowchart illustrating the state calculation process included in the measurement method of the eighth embodiment.

[0033] Figure 27 This is a diagram showing the configuration of the measuring device for the energy storage device according to the ninth embodiment. Detailed Implementation

[0034] Hereinafter, the measuring apparatus of various embodiments of the present invention will be described with reference to the accompanying drawings. The measuring apparatus of each embodiment functions as a device (control device) for detecting voltage changes in a storage device. This device supplies a constant current to the storage device, measures the voltage associated with the storage device to which a constant current is supplied, and detects the measured voltage change of the storage device. Furthermore, the device obtains the voltage change of the storage device based on electrical characteristics that serve as a reference for the storage device. These electrical characteristics, referred to herein as serving as a reference for the storage device, include: a reference voltage relative to the voltage of the storage device, the relationship between the voltage of the storage device and the electrostatic capacitance component of the storage device, and variations in the open-circuit voltage of the storage device, etc.

[0035] (First Implementation)

[0036] The following is for reference Figures 1 to 5 The measuring device (hereinafter referred to as "measuring device") 1 of the energy storage device 10 of the first embodiment will be described.

[0037] First, refer to Figure 1 The configuration of the energy storage device 10 and the configuration of the measuring device 1 will be explained. Figure 1 This is a diagram showing the configuration of measuring device 1.

[0038] The energy storage device 10 is, for example, a single energy storage cell of a lithium-ion secondary battery. The energy storage device 10 is not limited to a secondary battery (chemical battery), but may also be, for example, an electric double-layer capacitor. Furthermore, the energy storage device 10 may also be an energy storage module composed of multiple energy storage cells connected in series.

[0039] 10 images of energy storage devices Figure 1 This is represented by an equivalent circuit model. According to the equivalent circuit model, the energy storage device 10 has: a positive electrode 11, a negative electrode 12, an energy storage section 13, an internal resistor 14, and a parallel resistor 15. The energy storage section 13, the internal resistor 14, and the parallel resistor 15 are the equivalent circuit representing the internal state of the energy storage device 10.

[0040] The energy storage section 13 is the electrostatic capacitance component of the energy storage device 10. The energy storage section 13 is charged by accumulating charge when a voltage higher than the cell voltage of the energy storage device 10 is applied. In the energy storage section 13, double-layer reactions mainly occur when the current flowing through it during charging is relatively small, and chemical reactions mainly occur when the current flowing through it during charging is relatively large. Here, the electrostatic capacitance of the energy storage section 13 is denoted as Cst[F], and the current flowing through it is denoted as Ist[A].

[0041] The internal resistor 14 is a series resistor connected in series with the energy storage unit 13 between the positive electrode 11 and the negative electrode 12. Here, the resistance value of the internal resistor 14 is set as Rir [mΩ], and the current flowing through the internal resistor 14 is set as Iir [A].

[0042] The parallel resistor 15 is a resistor connected in parallel with the energy storage unit 13, also known as the discharge resistor. The self-discharge current, or leakage current, flows through the parallel resistor 15. Here, the resistance value of the parallel resistor 15 is set as Rpr [kΩ], and the self-discharge current flowing through the parallel resistor 15 is set as Ipr [A].

[0043] The measuring device 1 is a device for measuring the state of the energy storage device 10. The measuring device 1 includes: a constant current source 20 as a constant current supply unit, a reference voltage source 30 as a voltage generation unit, a voltmeter 40 as a measuring unit, a controller 50 as a calculation unit, and a display unit 60.

[0044] The constant current source 20 functions as a supply unit that supplies a constant current to the energy storage device 10. The constant current source 20 charges the energy storage device 10 by supplying a constant current to it for detecting the internal state of the energy storage device 10. The constant current source 20 maintains the current supplied to the energy storage device 10 at a predetermined level. The constant current source 20 charges the energy storage device 10 by supplying a constant current at a level below the overvoltage, where double-layer reaction mainly occurs. In this case, the constant current supplied from the constant current source 20 is, for example, 10 [μA].

[0045] Here, when charging the energy storage device 10 by applying a constant voltage, it is difficult to stably apply a constant voltage to the energy storage device 10 at a level below the overvoltage, where the double-layer reaction mainly occurs. In contrast, it is easy to supply a relatively small current using a constant current source 20. Therefore, in the measuring device 1, a constant current at a level below the overvoltage, where the double-layer reaction mainly occurs, can be stably supplied to the energy storage device 10 by using a constant current source 20.

[0046] The reference voltage source 30 generates a reference voltage relative to the voltage of the energy storage device 10, which serves as a reference. In this embodiment, the reference voltage source 30 is composed of a voltage generation circuit. The reference voltage of the reference voltage source 30 is determined such that the potential difference between the voltage of the energy storage device 10 and the reference voltage is less than the voltage of the energy storage device 10. For example, the reference voltage is set to a statistical value such as the average, mode, or median of the voltages of multiple energy storage devices 10.

[0047] In this embodiment, the reference voltage is set to a value within a specified range based on the voltage of the energy storage device 10. When the voltage of the energy storage device 10 is about 3V, the specified range can be set to a range from "-1V" to "+1V" relative to the voltage of the energy storage device 10.

[0048] Furthermore, from the viewpoint of ensuring the resolution of the voltmeter 40, when the voltmeter 40 is a 7.5-digit (7 1 / 2) DC voltmeter, the aforementioned specified range is preferably set to a range from "-100mV" to "+100mV" relative to the voltage of the energy storage device 10. When the potential difference between the voltage of the energy storage device 10 and the reference voltage is less than 100mV, even if the resolution of the 7.5-digit (7 1 / 2) DC voltmeter is increased to 10 [nV], the measured change in potential difference can be detected with high accuracy.

[0049] Instead, when using a DC voltmeter that can reduce the measurement range to ±10mV as the voltmeter 40, the above-mentioned range is preferably set to a range from "-10mV" to "+10mV" relative to the voltage of the energy storage device 10.

[0050] The voltmeter 40 functions as a measuring unit to measure the voltage associated with the energy storage device 10, which is supplied with a constant current. The voltmeter 40 is a DC voltmeter that measures the potential difference between the voltage of the energy storage device 10 and the reference voltage of the reference voltage source 30. Specifically, the voltmeter 40 primarily extracts the variation component in the voltage change of the energy storage device 10 caused by the constant current supplied from the constant current source 20. The voltmeter 40 outputs an electrical signal, sequentially displaying the measured potential difference, to the controller 50. In this electrical signal, part or all of the DC component in the voltage of the energy storage device 10 is removed.

[0051] In this embodiment, the voltmeter 40 measures the potential difference between the voltage of the energy storage device 10 and the reference voltage of the reference voltage source 30 at least twice, including a state in which a constant current is supplied from the constant current source 20. The voltmeter 40 includes a resistive element 41 and a detection unit 42 that functions as an element detection unit.

[0052] Resistive element 41 is a sensing resistor connected between the positive electrode 11 of the energy storage device 10 and the positive electrode of the reference voltage source 30. The resistance value of resistive element 41 is, for example, 1 [MΩ] or more and 10 [MΩ] or less. The current flowing through resistive element 41 is less than the constant current supplied from constant current source 20 to energy storage device 10.

[0053] From the viewpoint of ensuring measurement accuracy when measuring the internal state of the energy storage device 10, the current flowing through the resistive element 41 is preferably set to be less than a fraction of the constant current. In this embodiment, the resistance value of the resistive element 41 is set such that the current flowing through the resistive element 41 is about one-hundredth of the constant current. Therefore, the current flowing through the resistive element 41 is about 100 [nA].

[0054] The detection unit 42 detects the voltage generated across the resistive element 41 as the potential difference between the voltage of the energy storage device 10 and the reference voltage. The detection unit 42 outputs an electrical signal corresponding to the detected voltage value to the controller 50.

[0055] The controller 50 functions as a processing unit for detecting and measuring voltage changes in the energy storage device 10. The controller 50 is composed of a microcomputer equipped with a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface). Multiple microcomputers can also be used to construct the controller 50. The controller 50 is a control device that controls various actions of the measuring device 1 by reading the program stored in the ROM from the CPU.

[0056] The controller 50 controls the power supply from the constant current source 20 to the energy storage device 10 and uses the voltmeter 40 to calculate the internal state of the energy storage device 10. That is, the controller 50 calculates the internal state of the energy storage device 10 based on the potential difference measured by the voltmeter 40.

[0057] In this embodiment, the controller 50 acquires an electrical signal from the voltmeter 40 while the constant current source 20 supplies a constant current to the energy storage device 10, and detects the time change of the potential difference between the voltage of the energy storage device 10 and the reference voltage indicated by the electrical signal. The detected time change of the potential difference is used as the voltage change of the energy storage device 10, i.e., the variation component after removing the DC component. Based on the detected voltage change of the energy storage device 10, the controller 50 infers the internal state of the energy storage device 10, such as its self-discharge state.

[0058] For example, the controller 50 determines the condition of the internal state of the energy storage device 10 based on the detected voltage change of the energy storage device 10. Alternatively, the controller 50 may also calculate the self-discharge current flowing through the parallel resistor 15, the resistance value of the parallel resistor 15, or the electrostatic capacitance of the energy storage section 13 based on the detected voltage change of the energy storage device 10.

[0059] In this embodiment, when the voltage variation of the energy storage device 10 is within the normal range, the controller 50 determines that the energy storage device 10 is normal; when the voltage variation of the energy storage device 10 is outside the normal range, the controller 50 determines that the energy storage device 10 is abnormal. In this way, the controller 50 determines whether the energy storage device 10 is functioning properly.

[0060] The controller 50 generates information related to the self-discharge state of the energy storage device 10, such as determination information indicating the determined result or internal information indicating the calculated self-discharge current. In this way, the controller 50 generates information related to the self-discharge state of the energy storage device 10 based on the potential difference between the voltage of the energy storage device 10 and the reference voltage.

[0061] The display unit 60 displays information such as the determination result or calculation result of the controller 50 to notify the user. The display unit 60 is, for example, a touch screen, configured so that the user can visually confirm the information and operate it.

[0062] Next, refer to Figures 2 to 5 The method for measuring the internal state of the energy storage device 10 using the measuring device 1 will be described. Figure 2 and Figure 3 This is a flowchart illustrating the measurement method using the measuring apparatus 1 of this embodiment. Figure 4 This is a graph illustrating an example of the change in the potential difference between the voltage of the energy storage device 10 and the reference voltage relative to the charging time of the energy storage device 10. Figure 5This is a graph showing the change in voltage of the energy storage device 10 itself relative to the charging time of the energy storage device 10, as a comparative example.

[0063] exist Figure 2 In the example shown, for instance, in an environment where the energy storage device 10 is housed in a constant temperature bath that maintains a fixed ambient temperature and thus suppresses temperature changes in the energy storage device 10, the measuring device 1 performs a process to measure the state of the energy storage device 10.

[0064] First, when performing the above process, the measuring device 1 is connected to the energy storage device 10. In this embodiment, the energy storage device 10, the constant current source 20, the reference voltage source 30, and the voltmeter 40 are prepared. The constant current source 20 is connected in parallel with the energy storage device 10, and the voltmeter 40 is connected between the positive electrode 11 of the energy storage device 10 and the positive electrode of the constant current source 20.

[0065] In step S1, the reference voltage source 30 generates a reference voltage relative to the voltage of the energy storage device 10, which serves as a reference. For example, power is supplied to the reference voltage source 30 via the controller 50.

[0066] In step S2, the controller 50 causes the voltmeter 40 to measure the potential difference between the voltage of the energy storage device 10 and the reference voltage of the reference voltage source 30. Thus, an electrical signal corresponding to the potential difference between the voltage of the energy storage device 10 and the reference voltage is input to the controller 50 via the voltmeter 40.

[0067] In step S3, the controller 50 supplies a constant current from the constant current source 20 to the energy storage device 10 to begin charging.

[0068] In step S4, the controller 50 performs a state calculation process based on the potential difference between the voltage of the energy storage device 10 and the reference voltage, as indicated by an electrical signal, to calculate the internal state of the energy storage device 10. For this state calculation process, refer to... Figure 3 As described later.

[0069] When step S4 is completed, the series of processing steps for the measurement method in this embodiment ends.

[0070] exist Figure 3 An example of the state calculation process performed in step S4 is shown. In this example, as state calculation process (S4), the controller 50 determines whether the energy storage device 10 is good or bad based on the potential difference between the voltage of the energy storage device 10 and the reference voltage.

[0071] In step S41, the controller 50 determines whether the charging time, which is the elapsed time from the start of charging, exceeds a predetermined time. The predetermined time is, for example, preset to be the length of time during which the time change of the potential difference in the energy storage device 10 differs between normal and abnormal conditions, when the resolution of the voltmeter 40 is increased to the limit of the resolution that can measure the potential difference.

[0072] In step S41, if it is determined that the charging time has not exceeded the predetermined time, the controller 50 waits until it is determined that the charging time has exceeded the predetermined time. On the other hand, if it is determined that the charging time has exceeded the predetermined time, the controller 50 proceeds to step S42.

[0073] In this way, the voltmeter 40 measures the initial potential difference as the potential difference when a constant current is supplied (when charging begins) and the charging potential difference as the potential difference when a constant current is supplied from the constant current source 20. That is, the voltmeter 40 measures the potential difference between the voltage of the energy storage device 10 and the reference voltage more than twice, including the state when a constant current is supplied from the constant current source 20.

[0074] In step S42, the controller 50 detects the voltage change of the energy storage device 10 based on the potential difference between the voltage of the energy storage device 10 and the reference voltage, as measured by the voltmeter 40. Specifically, the controller 50 calculates an approximate linear relationship for the voltage change of the energy storage device 10 based on the initial potential difference at the start of charging and the charging potential difference under the condition that a constant current is supplied from the constant current source 20. More specifically, the controller 50 calculates an approximate linear relationship for the voltage change of the energy storage device 10 using the least squares method based on the potential difference measured in each control cycle.

[0075] Alternatively, the controller 50 can also be configured to detect the voltage change of the energy storage device 10 based on the difference between the initial potential difference at the start of charging and the charging potential difference under the condition of constant current supplied from the constant current source 20. In this case, it is sufficient to measure the voltage of the energy storage device 10 twice using the voltmeter 40, so the potential difference measurement can be performed, for example, by using a multiplexer for switching. Therefore, the measuring device 1 can be simplified.

[0076] In step S43, the controller 50 determines whether the slope of the approximate straight line is within a specified range. If the slope of the approximate straight line is determined to be within the specified range between the upper and lower limits, the energy storage device 10 is in a normal state, and therefore the controller 50 moves to step S44. On the other hand, if the slope of the approximate straight line is determined to be outside the specified range in step S43, i.e., greater than the upper limit of the specified range or less than the lower limit of the specified range, the energy storage device 10 is in an abnormal state, and therefore the controller 50 moves to step S45.

[0077] Here, refer to Figure 4 and Figure 5 Specific examples will be provided to illustrate the processing of steps S42 and S43. Figure 4 and Figure 5 The horizontal axis represents the charging time [s], which is the elapsed time since the start of charging of the energy storage device 10.

[0078] exist Figure 4 In the example shown, the voltage difference between the storage device 10 and the reference voltage is measured by voltmeter 40. The DC component of the measured potential difference is relatively small, so the resolution of voltmeter 40 is set to 10 [nV]. Figure 4 The vertical axis represents the difference [μV] between the charging potential difference measured by voltmeter 40 and the initial potential difference.

[0079] Figure 4 The solid line shown represents the change in potential difference when the energy storage device 10 is in normal operation. The straight line of the solid line is an approximate straight line Ln1 representing the change in potential difference obtained through the processing in step S42. On the other hand, Figure 4 The dashed line data represents the change in potential difference when the energy storage device 10 is in an abnormal state. The straight line of the dashed line is an approximate straight line La1 of the change in potential difference obtained through the processing in step S42. Hereinafter, the slope of the approximate straight line Ln1 is set as Rn, and the slope of the approximate straight line La1 is set as Ra.

[0080] also, Figure 4 The two double-dotted lines shown represent the upper limit Rmax and lower limit Rmin of the slope of the approximate straight line, respectively. The slope between the two double-dotted lines represents the slope of the energy storage device 10 under normal conditions. It should be noted that the upper limit Rmax and lower limit Rmin of the slope of the approximate straight line are set to, for example, ±10% of the approximate straight line obtained by prior measurement using the energy storage device 10 under normal conditions.

[0081] Reference Figure 4 The approximate straight line Ln1 (slope Rn), represented by a solid line, lies between the upper limit Rmax and the lower limit Rmin of the slope of the approximate straight line. Therefore, the controller 50 determines that the energy storage device 10 is in a normal state. On the other hand, the approximate straight line La1 (slope Ra), represented by a dashed line, does not lie between the upper limit Rmax and the lower limit Rmin of the slope of the approximate straight line. Therefore, the controller 50 determines that the energy storage device 10 is in an abnormal state.

[0082] In this way, the controller 50 determines whether the energy storage device 10 is in a normal or abnormal state based on whether the slope of the approximate straight line is between the upper limit value Rmax and the lower limit value Rmin. That is, the controller 50 detects the voltage change of the energy storage device 10 after removing most of the DC component based on the measured potential difference between the voltage of the energy storage device 10 and the reference voltage, and determines that the energy storage device 10 is normal if the voltage change is within the normal range.

[0083] It should be noted that, in Figure 4 In the example shown, the determination of the quality of the energy storage device 10 takes 60 seconds (T1), but the difference in slope between the approximate straight line Ln1 (represented by the solid line) and the approximate straight line La1 (represented by the dashed line) can be clearly confirmed in about 20 seconds. In this way, the determination of the quality of the energy storage device 10 can be performed in a short time of about tens of seconds in the measuring device 1.

[0084] On the other hand, Figure 5 In this study, the voltage of the energy storage device 10 itself was measured as a comparative example. The DC component was not removed, so the resolution of the voltmeter was set to 10 [μV]. Figure 5 The vertical axis represents the difference [μV] between the charging voltage and the open-circuit voltage (OCV) of the energy storage device 10 when it is supplied with a constant current from the constant current source 20.

[0085] The solid line represents the voltage change when the energy storage device 10 is in normal operation. The straight line of the solid line is an approximate straight line Ln0 of the voltage change obtained through the processing in step S42. On the other hand, Figure 5 The data shown by the dashed line represents the voltage change when the energy storage device 10 is in an abnormal state. The straight line of the dashed line is an approximate straight line La0 of the voltage change obtained through the processing in step S42.

[0086] In measuring the voltage of the energy storage device 10 itself, compared to measuring the potential difference between the voltage of the energy storage device 10 and the reference voltage, the DC component of the voltage change of the energy storage device 10 is larger. Therefore, as the resolution of the voltmeter increases, the influence of the voltmeter's internal noise becomes greater. Consequently, in Figure 5 In the example shown, the voltmeter's resolution is set to be greater than that of the standard voltmeter. Figure 4 The example shown is low.

[0087] The result is, as Figure 5 As shown, determining the quality of the energy storage device 10 requires a measurement time T0 of 600 s. However, the difference in slope between the approximate straight line Ln0 (represented by a solid line) and the approximate straight line La0 (represented by a dashed line) can be confirmed in approximately 200 s, thus allowing for a quality determination in a short time of about a few minutes. However, it is known that in the method for measuring the voltage of the energy storage device 10 itself, compared to… Figure 4 Compared to the measurement time T1 of this embodiment, it takes about ten times longer to determine the quality of the energy storage device 10.

[0088] As described above, in this embodiment, the energy storage device 10 is charged by a constant current from the constant current source 20, and the voltage is measured more than twice, including during the constant current supply period, thereby detecting the voltage change of the energy storage device 10. Then, it is determined whether the detected voltage change of the energy storage device 10 is within the normal range. If the voltage change is within the normal range, the energy storage device 10 is determined to be normal. Therefore, there is no need to wait for the voltage of the energy storage device 10 to decrease due to self-discharge, thus the time spent determining the condition of the energy storage device 10 is short.

[0089] In addition, in this embodiment, a voltmeter 40 is used to measure the potential difference between the voltage of the energy storage device 10 and the reference voltage. Compared with measuring the voltage of the energy storage device 10 itself, the resolution of the voltmeter 40 can be improved while suppressing the influence of internal noise. As a result, the time required to determine the quality of the energy storage device 10 can be shortened.

[0090] Therefore, the quality of the energy storage device 10 can be determined in a short time.

[0091] At this time, the constant current source 20 supplies a constant current, the magnitude of which is less than the overvoltage and mainly involves double-layer reaction, to charge the energy storage device 10. Therefore, the magnitude of the constant current is small, and thus the ratio of the current Ist [A] flowing through the energy storage section 13 to the current Ipr [A] flowing through the parallel resistor 15 is large. Therefore, the difference in the slope of the charging curve caused by the presence or absence of the parallel resistor 15 becomes larger, making it easier to determine whether the energy storage device 10 is functioning properly.

[0092] return Figure 3 When the processing of step S43 is completed, the controller 50 proceeds to step S44.

[0093] In step S44, assuming the energy storage device 10 is in a normal state, the controller 50 displays its message on the display unit 60 to notify the user. On the other hand, in step S45, assuming the energy storage device 10 is in an abnormal state, the controller 50 displays its message on the display unit 60 to notify the user.

[0094] The condition of the energy storage device 10 is determined by performing the above state operation process (S4).

[0095] In the above embodiment, the voltmeter 40 measures the potential difference between the voltage of the energy storage device 10 and the reference voltage as the initial potential difference after charging of the energy storage device 10 begins. Alternatively, the voltmeter 40 may also measure the potential difference between the voltage of the energy storage device 10 and the reference voltage as the initial potential difference before charging of the energy storage device 10 begins. In this case, the potential difference between the voltage of the energy storage device 10 and the reference voltage can be measured more than twice, including in a constant current supply state, thus allowing an approximate linear change in the voltage of the energy storage device 10 to be obtained.

[0096] Next, the effects of the first embodiment will be explained.

[0097] In this embodiment, the measuring devices 1 and 1A constitute a device for detecting voltage changes in the energy storage device 10. The measuring device 1 includes: a constant current source 20 (supply unit) that supplies a constant current to the energy storage device 10; a voltmeter 40 (measuring unit) that measures the voltage related to the energy storage device 10 supplied with a constant current; and a controller 50 (processing unit) that detects the measured voltage changes in the energy storage device 10. The measuring device 1 then acquires the voltage changes of the energy storage device 10 based on electrical characteristics that serve as a reference for the energy storage device 10. Examples of electrical characteristics serving as a reference for the energy storage device 10 include a reference voltage relative to the voltage of the energy storage device 10, the relationship between the output voltage and the electrostatic capacitance in the energy storage device 10, and variations in the open-circuit voltage of the energy storage device 10.

[0098] Furthermore, regarding the method for detecting voltage changes in the energy storage device 10 in this embodiment, a constant current is supplied to the energy storage device 10, and the voltage associated with the energy storage device 10 to which the constant current is supplied is measured, and the measured voltage change of the energy storage device is detected. This method obtains the voltage change of the energy storage device 10, which varies according to the magnitude of the self-discharge current or discharge resistance of the energy storage device 10, based on the electrical characteristics that serve as a reference for the energy storage device 10.

[0099] Based on these configurations, by supplying a constant current to the energy storage device 10, the slope of the voltage change of the energy storage device 10, which is correlated with the internal state of the energy storage device 10 and is approximately linear in this embodiment, is increased. In this case, the voltage change of the energy storage device 10 is detected based on the electrical characteristics that serve as a reference for the energy storage device 10, thereby enabling high-precision acquisition of the voltage change of the energy storage device 10. Therefore, the state of the energy storage device 10 can be acquired with high precision in a short time.

[0100] Furthermore, in this embodiment, the measuring devices 1 and 1A measure the potential difference between the voltage of the energy storage device 10 and the reference voltage based on a reference voltage relative to the voltage of the energy storage device 10, thereby detecting the voltage change of the energy storage device 10 supplied with a constant current. Specifically, it is described below.

[0101] The measuring device 1 for measuring the state of the energy storage device 10 in this embodiment includes: a constant current source 20 for supplying a constant current to the energy storage device 10; and a reference voltage source 30 for generating a reference voltage relative to the voltage of the energy storage device 10. Furthermore, the measuring device 1 includes: a voltmeter 40 for measuring the potential difference between the voltage of the energy storage device 10 and the reference voltage; and a controller 50 for calculating the internal state of the energy storage device 10 based on the measured change in potential difference.

[0102] Furthermore, regarding the method for measuring the state of the energy storage device 10, a reference voltage is generated relative to the voltage of the energy storage device 10 as a reference. Moreover, regarding the measurement method, a constant current is supplied to the energy storage device 10, the potential difference between the voltage of the energy storage device 10 and the reference voltage is measured, and the internal state of the energy storage device 10 is calculated based on the measured change in potential difference.

[0103] The voltage variation of the energy storage device 10 changes depending on the internal state of the energy storage device 10. Therefore, according to the above configuration, since a constant current is supplied to the energy storage device 10, the voltage variation of the energy storage device 10 increases, thereby shortening the time required to measure the internal state of the energy storage device 10.

[0104] In addition, based on the above configuration, instead of directly measuring the voltage of the energy storage device 10, the potential difference between the voltage of the energy storage device 10 and the reference voltage is measured. Therefore, the variation component of the voltage of the energy storage device 10 can be mainly extracted. As a result, the resolution of the voltmeter 40 can be improved, and thus the voltage change of the energy storage device 10 can be quickly estimated.

[0105] In this way, the voltage change of the energy storage device 10 caused by different internal states can be amplified and the resolution of the voltmeter 40 can be improved, so that the state of the energy storage device 10 can be determined in a short time.

[0106] Furthermore, based on the above configuration, compared to supplying a constant voltage to the energy storage device 10, it is easier to supply a smaller current to the energy storage device 10 using the constant current source 20. Therefore, in the measuring device 1, a constant current of a magnitude smaller than the overvoltage, in which the double-layer reaction mainly occurs, can be stably supplied to the energy storage device 10 by using the constant current source 20.

[0107] Furthermore, the voltmeter 40 in this embodiment includes: a resistive element 41 connected between the positive terminals of the energy storage device 10 and the reference voltage source 30; and a detection unit 42 that detects the voltage generated by the resistive element 41 as the potential difference between the voltage of the energy storage device 10 and the reference voltage.

[0108] According to this configuration, by setting a resistor element 41 with a relatively large resistance value, leakage current flowing from the constant current source 20 to the voltmeter 40 and excess current flowing from the reference voltage source 30 to the energy storage device 10 can be suppressed. As a result, the reduction in the estimation accuracy of the internal state of the energy storage device 10 can be suppressed.

[0109] Furthermore, the current flowing through the resistor element 41 in this embodiment is less than the constant current supplied from the constant current source 20.

[0110] According to this configuration, a current less than the constant current flows through the resistive element 41, thus suppressing the excessive or insufficient constant current supplied to the energy storage device 10, thereby suppressing the reduction of the measurement accuracy of the energy storage device 10.

[0111] Furthermore, in this embodiment, the reference voltage generated by the reference voltage source 30 is set such that the voltage generated across the resistor element 41 is less than the voltage of the energy storage device 10.

[0112] According to this configuration, compared with the case of directly measuring the voltage of the energy storage device 10, the DC component in the voltage change of the energy storage device 10 is reduced, thus the resolution of the voltmeter 40 can be improved accordingly. Therefore, the internal noise of the voltmeter 40 can be suppressed and the voltage change of the energy storage device 10 can be detected in a short time.

[0113] Furthermore, in this embodiment, the constant current source 20 supplies a constant current to the energy storage device 10 that is less than the overvoltage and where the double-layer reaction mainly occurs.

[0114] Based on this configuration, the magnitude of the constant current is relatively small, therefore the ratio of the current Ist[A] flowing through the energy storage unit 13 to the current Ipr[A] flowing through the parallel resistor 15 becomes larger. As a result, the difference in the slope of the charging curve caused by the presence or absence of the parallel resistor 15 becomes larger, making it easier to determine whether the energy storage device 10 is functioning properly.

[0115] Furthermore, in this embodiment, the controller 50 generates information related to the self-discharge state of the energy storage device 10 based on the change in potential difference measured by the voltmeter 40. For example, the controller 50 outputs the result of determining whether the energy storage device 10 is good or bad as information related to the self-discharge state of the energy storage device 10.

[0116] Based on this configuration, the resolution of the voltmeter 40 can be improved by measuring the potential difference between the voltage of the energy storage device 10 and the reference voltage, thus shortening the time required to detect voltage changes in the energy storage device 10. Consequently, internal information related to the self-discharge information of the energy storage device 10 can be generated in a short time.

[0117] In addition, the voltmeter 40 measures the initial potential difference when the constant current is supplied and the charging potential difference when the constant current is supplied from the constant current source 20. The controller 50 detects the voltage change of the energy storage device 10 based on the initial potential difference and the charging potential difference.

[0118] According to this configuration, the controller 50 can detect voltage changes based on the difference between the initial potential difference when constant current is supplied and the charging potential difference when constant current is supplied from the constant current source 20. In this case, it is sufficient to measure the potential difference between the voltage of the energy storage device 10 and the reference voltage at least twice using the voltmeter 40, and therefore, the measurement can also be performed by switching using a multiplexer, for example. Thus, the measuring device 1 can be simplified.

[0119] (Second Implementation)

[0120] Next, refer to Figure 6 The reference voltage source 30 of the measuring device 1A in the second embodiment will be described. Figure 6 This diagram shows the configuration of the measuring device 1A. In this embodiment, unlike the first embodiment, another energy storage device 10A is used as the reference voltage source 30.

[0121] In this embodiment, the reference voltage source 30 is another energy storage device 10A of the same type as the energy storage device 10. The energy storage device 10A generates a reference voltage that serves as a reference relative to the voltage of the energy storage device 10, which is the object of measurement.

[0122] In determining the quality of the energy storage device 10, it is assumed that multiple energy storage devices 10 and 10A are placed in the same environment. For the energy storage devices 10 and 10A, due to changes in their ambient temperature and humidity, their internal states change in the same way.

[0123] For example, as the ambient temperature changes, the change in the internal temperature of the energy storage device 10 increases, and consequently, the slope of the voltage change in the energy storage device 10 also changes. As a countermeasure, in this embodiment, the voltage of another energy storage device 10A placed in the same environment as the energy storage device 10 is used as the reference voltage of the energy storage device 10.

[0124] The environmental variation component caused by differences in ambient temperature and humidity in the voltage change of the energy storage device 10 is also superimposed on the voltage of the energy storage device 10A in the same way. Therefore, when detecting the voltage change of the energy storage device 10, the environmental variation component in the voltage of the energy storage device 10 is mainly removed by measuring the potential difference between the voltage of the energy storage device 10 and the voltage of the energy storage device 10A, thus improving the detection accuracy of voltage change.

[0125] As described above, according to the second embodiment, when measuring the potential difference between the voltage of the energy storage device 10 and the reference voltage, the voltage of the energy storage device 10A is used as the reference voltage, thereby reducing the variation in voltage of the energy storage device 10 caused by different measurement environments.

[0126] Furthermore, by using other energy storage devices 10A as a reference voltage source 30, the measuring device 1A can be easily constructed compared to the case of using a voltage generation circuit. Therefore, the measuring device 1A can be easily constructed and the internal state of the energy storage device 10 can be measured with high accuracy.

[0127] (Third Implementation)

[0128] Next, the controller 50 of the measuring device 1 in the third embodiment will be described. Hereinafter, the resistance value of the parallel resistor 15 will be referred to as the discharge resistor Rpr, and the current flowing through the parallel resistor 15 will be referred to as the self-discharge current Ipr.

[0129] In this embodiment, the controller 50 calculates the discharge resistance Rpr or self-discharge current Ipr of the energy storage device 10, which differs from the first and second embodiments.

[0130] The controller 50 switches the constant current supplied from the constant current source 20 to the energy storage device 10 between a constant current showing a first current value and a constant current showing a second current value. Hereinafter, the constant current showing the first current value will also be referred to as the "first constant current", and the constant current showing the second current value will also be referred to as the "second constant current".

[0131] In this embodiment, the first current value is set to one or several times the reference value of the self-discharge current Ipr of the energy storage device 10, similar to the constant current in the first embodiment. For example, the first current value is set to 10 [μA] times the reference value of the self-discharge current Ipr. Furthermore, the second current value is set to several tens of times or more the reference value of the self-discharge current Ipr of the energy storage device 10. For example, the second current value is set to fifty times the reference value of the self-discharge current Ipr.

[0132] The aforementioned reference value for the self-discharge current Ipr is known information, such as being determined in advance using statistical data summarizing the self-discharge currents Ipr of multiple energy storage devices 10 or test results of the self-discharge current Ipr of a specific energy storage device 10 with normal electrical characteristics.

[0133] Next, the controller 50 detects the voltage change of the energy storage device 10 based on the potential difference between the voltage of the energy storage device 10 and the reference voltage, according to the constant current supplied to the energy storage device 10 from the constant current source 20.

[0134] In this embodiment, such as Figure 4As shown, for each constant current, the controller 50 calculates the slope of the voltage change of the energy storage device 10 based on the initial potential difference when the constant current is supplied and the charging potential difference when the constant current is supplied from the constant current source 20. Alternatively, the controller 50 can also calculate an approximate straight line Ln1 of the voltage change of the energy storage device 10 for each constant current supplied to the energy storage device 10, and use the slope of this approximate straight line Ln1 as the slope of the voltage change.

[0135] The controller 50 calculates the self-discharge current Ipr of the energy storage device 10 using the slope of the voltage change of the energy storage device 10 calculated for each constant current and the formula for calculating the electrostatic capacitance Cst of the energy storage section 13 of the energy storage device 10. Here, the calculation method of the self-discharge current Ipr of the energy storage device 10 will be explained.

[0136] The formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the slope A1 of the voltage change during charging of the energy storage device 10 with a constant current of the first current value I1, and the charging current Ist[A] of the energy storage unit 13. The charging current Ist[A] of the energy storage unit 13 is the amount of charge stored in the electrostatic capacitance Cst per unit time, equivalent to the charge flowing from the capacitor as a current through the energy storage unit 13. Figure 1 The value (I1 - Ipr) is obtained by subtracting the self-discharge current Ipr flowing through the parallel resistor 15 from the first current value I1 of the internal resistor 14 shown.

[0137] Therefore, the formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10, the first current value I1, and the slope A1 of the voltage change when the energy storage device 10 is charged with the first constant current, as shown in the following formula (1).

[0138] [Formula 1]

[0139]

[0140] Furthermore, the formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the second current value I2 and the slope A2 of the voltage change when the constant current of the second current value I2 is charging the energy storage device 10, as shown in the following formula (2).

[0141] [Formula 2]

[0142]

[0143] In the above formula (2), the charging current Ist[A] for the energy storage unit 13 is equivalent to the value (I2 - Ipr) obtained by subtracting the self-discharge current Ipr from the value of the second constant current supplied to the energy storage device 10. However, Figure 1The current value I2 flowing through the internal resistor 14 is as shown above, which is significantly greater than the self-discharge current Ipr flowing through the parallel resistor 15, and can therefore be approximated as in the following formula (3).

[0144] [Formula 3]

[0145] I2≈(I2-I pr )···(3)

[0146] Therefore, in the above formula (2), instead of the current value (I2-Ipr) obtained by subtracting the self-discharge current Ipr from the current value I2 of the second constant current, the current value I2 of the second constant current is used.

[0147] Next, if the self-discharge current Ipr is solved using formulas (1) and (2), the following formula (4) is derived.

[0148] [Formula 4]

[0149]

[0150] In this way, the self-discharge current Ipr of the energy storage device 10 can be calculated by substituting the slopes A1 and A2 of the voltage change obtained for each constant current and the current values ​​I1 and I2 of the constant current into the formula for calculating the electrostatic capacitance Cst of the energy storage section 13.

[0151] Next, the controller 50 calculates the discharge resistance Rpr of the energy storage device 10 based on the calculated self-discharge current Ipr.

[0152] In this embodiment, the controller 50 calculates the discharge resistance Rpr of the energy storage device 10 by dividing the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr of the energy storage device 10. The open-circuit voltage (OCV) of the energy storage device 10 can be the voltage value of the energy storage device 10 measured by the voltmeter 40 before the constant current supply begins, or it can be a voltage value predetermined by using test results of the energy storage device 10, etc.

[0153] Instead, the controller 50 can also pre-store a correspondence table or function representing the relationship between the self-discharge current Ipr and the discharge resistance Rpr of the energy storage device 10, and use the correspondence table or function to calculate the discharge resistance Rpr.

[0154] Subsequently, the controller 50 determines whether the energy storage device 10 is functioning properly based on the calculated discharge resistance Rpr of the energy storage device 10.

[0155] In this embodiment, the controller 50 determines whether the calculated value of the discharge resistance Rpr of the energy storage device 10 is within a specified resistance range. The upper and lower limits of the specified resistance range are predetermined using statistical data summarizing the discharge resistances Rpr of multiple energy storage devices 10 or test results of a specific energy storage device 10 with normal electrical characteristics.

[0156] If the calculated value of the discharge resistor Rpr is within the specified resistance range, the controller 50 determines that the energy storage device 10 is in a normal state; if the calculated value of the discharge resistor Rpr is not within the specified range, the controller 50 determines that the energy storage device 10 is abnormal.

[0157] Alternatively, a diagnostic table representing the normal or abnormal state of the energy storage device 10 according to each discharge resistance Rpr can be pre-stored in the controller 50. In this case, when the discharge resistance Rpr of the energy storage device 10 is calculated, the controller 50 refers to the diagnostic table and establishes a specific internal state of the energy storage device 10 corresponding to the calculated discharge resistance Rpr.

[0158] Finally, the controller 50 outputs a determination result indicating whether the energy storage device 10 is in a normal or abnormal state to the display unit 60. The determination result of the energy storage device 10 is then displayed on the screen of the display unit 60.

[0159] It should be noted that in this embodiment, the controller 50 determines the condition of the energy storage device 10 based on the calculated value of the discharge resistance Rpr. However, alternatively, the calculated value of the self-discharge current Ipr can also be used to determine whether the energy storage device 10 is in a normal state. In this case, the controller 50 determines, for example, whether the calculated value of the self-discharge current Ipr is within a specified current range. When it is determined that the calculated value is within the specified current range, the energy storage device 10 is determined to be in a normal state.

[0160] Furthermore, in this embodiment, the controller 50 controls the operation of the constant current source 20 by sequentially supplying constant currents with different current values ​​to the energy storage device 10. However, if the electrostatic capacitance Cst of the energy storage unit 13 is known, it is also possible to supply only the constant current showing the first current value I1. In this case, since the controller 50 has the electrostatic capacitance Cst of the energy storage unit 13 stored in advance, the controller 50 substitutes the electrostatic capacitance Cst, the first current value I1, and the slope A1 of the voltage change corresponding to the first current value I1 into the above formula (1) to calculate the self-discharge current Ipr.

[0161] Regarding the electrostatic capacitance Cst of the energy storage unit 13 stored in the controller 50, it can be predetermined using statistical data summarizing the electrostatic capacitance Cst of the energy storage units 13 in multiple energy storage devices 10 or test results of a specific energy storage device 10. Alternatively, the controller 50 can charge the energy storage device 10 with a constant current showing a second current value I2, and substitute the slope A2 of the voltage change and the second current value I2 into the above formula (2) to calculate the electrostatic capacitance Cst of the energy storage unit 13.

[0162] Next, refer to Figure 7 The state calculation processing (S4) of the measuring device 1 using the third embodiment will be described. Figure 7 This is a flowchart illustrating the measurement method using measuring device 1.

[0163] The state operation processing (S4) in this embodiment is replaced by the processing of steps S51 to S55. Figure 3 The process of step S43 is shown. Therefore, only the processes of steps S51 to S55 will be described here.

[0164] In step S42, the controller 50 determines the result to pass Figure 2 In step S3, an approximate straight line Ln1 is set to show the voltage change of the energy storage device 10 during constant current charging with the first current value I1, and the slope A1 of the approximate straight line Ln1 is obtained, and the process proceeds to step S51.

[0165] In step S51, the controller 50 switches the constant current supplied from the constant current source 20 to the energy storage device 10 from a first constant current to a second current value I2 that represents a current greater than the first current value I1.

[0166] The processing in steps S52 and S53 is the same as that in steps S41 and S42, respectively. Therefore, in steps S52 and S53, the controller 50 only measures the potential difference between the voltage of the energy storage device 10 and the reference voltage at a predetermined time, calculates the approximate straight line Ln2 of the voltage change during the second constant current charging, and obtains the slope A2 of the approximate straight line Ln2.

[0167] In step S54, the controller 50 calculates the discharge resistance Rpr of the energy storage device 10 based on the slopes A1 and A2 of an approximate straight line obtained by constant current for each of the first current value I1 and the second current value I2.

[0168] In this embodiment, the controller 50 substitutes the first current value I1, the slope A1 of the approximate straight line, the second current value I2, and the slope A2 of the approximate straight line into the above formula (4) to calculate the self-discharge current Ipr of the energy storage device 10. Then, the controller 50 divides the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr of the energy storage device 10 to calculate the discharge resistance Rpr of the energy storage device 10.

[0169] In step S55, the controller 50 determines whether the energy storage device 10 is normal based on the calculated discharge resistance Rpr of the energy storage device 10.

[0170] In this embodiment, the controller 50 determines whether the calculated value of the discharge resistor Rpr is within a specified resistance range. If the calculated value of the discharge resistor Rpr is determined to be within the specified resistance range, the energy storage device 10 is in a normal state, and therefore the controller 50 proceeds to step S44. On the other hand, if the calculated value of the discharge resistor Rpr is determined to be outside the specified resistance range, i.e., greater than the upper limit of the resistance range or less than the lower limit of the resistance range, the energy storage device 10 is in an abnormal state, and therefore the controller 50 proceeds to step S45.

[0171] The condition of the energy storage device 10 is determined by performing the above state operation process (S4).

[0172] It should be noted that, in Figure 7 In the example shown, the controller 50 switches the magnitude of the constant current supplied to the energy storage device 10 only once and calculates the slope of the voltage change of the energy storage device 10 twice, thereby calculating the self-discharge current Ipr of the energy storage device 10. Alternatively, the magnitude of the constant current can be switched multiple times and the slope of the approximate straight line of voltage change can be calculated sequentially, thereby calculating multiple self-discharge currents Ipr, and the average or median value of these can be used as the final result.

[0173] Furthermore, in this embodiment, the controller 50 switches the magnitude of the constant current supplied from the constant current source 20 to the positive electrode 11 of the energy storage device 10 and calculates the discharge resistance Rpr of the energy storage device 10, but is not limited thereto. For example, the connection relationship between the constant current source 20 and the energy storage device 10 can be reversed, and the constant current can be supplied from the constant current source 20 to the negative electrode 12 of the energy storage device 10 to discharge the energy storage device 10. In this state, the magnitude of the constant current is switched. In this case, the discharge resistance Rpr of the energy storage device 10 can also be calculated as in the above embodiment.

[0174] Furthermore, in this embodiment, the magnitude of the constant current supplied to the energy storage device 10 from the constant current source 20 is switched, but the self-discharge current Ipr and the discharge resistance Rpr can still be calculated even if the direction of the constant current is switched. Hereinafter, a method for calculating the self-discharge current Ipr of the energy storage device 10 when the direction of the constant current supplied to the energy storage device 10 is switched will be briefly explained.

[0175] The electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10 and the slope Ac of the voltage change when the energy storage device 10 is charged with a constant current of the first current value I1, as shown in the following formula (5). Furthermore, the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10 and the slope Ad of the voltage change when the energy storage device 10 is discharged due to a constant current of the second current value I2, as shown in the following formula (6).

[0176] [Formula 5]

[0177]

[0178] [Formula 6]

[0179]

[0180] If the self-discharge current Ipr is solved using the above formulas (5) and (6), the following formula (7) is derived.

[0181] [Formula 7]

[0182]

[0183] Therefore, by substituting the slope Ac of the voltage change during constant current charging (showing the first current value I1) and the slope Ad of the voltage change during constant current discharging (showing the second current value I2) into the above formula (7), the self-discharge current Ipr of the energy storage device 10 can be calculated. Then, by dividing the open-circuit voltage (OCV) of the energy storage device 10 by the calculated self-discharge current Ipr, the discharge resistance Rpr is calculated.

[0184] In this case, regarding the first current value I1 and the second current value I2, at least one of their absolute values ​​can be set to one or several times the reference value of the self-discharge current Ipr. The absolute values ​​of both can be the same or different. For example, the first current value I1 can be set to 10 [μA], which is one times the reference value of the self-discharge current Ipr, and the second current value I2 can be set to the value obtained by multiplying the first current value I1 by "-1", i.e., -10 [μA]. Furthermore, regarding the slopes Ac and Ad of the voltage change, by... Figure 4 The same method is used to obtain the information.

[0185] Furthermore, in this embodiment, the controller 50 switches the magnitude of the constant current, but it can also switch the direction of the constant current after switching the magnitude, or vice versa. In this case, multiple self-discharge currents Ipr can be obtained, and their average value can be used as the final result.

[0186] Furthermore, in this embodiment, the controller 50 calculates the self-discharge current Ipr of the energy storage device 10 by switching the magnitude of the constant current, but it is also possible to calculate the self-discharge current Ipr without switching the magnitude of the constant current. For example, if the electrostatic capacitance Cst of the energy storage unit 13 in formula (1) is known, the slope A1 of the approximate straight line of the voltage change of the energy storage device 10 can also be obtained, and the slope A1, the first current value I1, and the known electrostatic capacitance Cst can be substituted into the above formula (1) to calculate the self-discharge current Ipr.

[0187] Alternatively, the measured or predicted values ​​can be substituted into the electrostatic capacitance Cst of the energy storage unit 13 and the first current value I1 in the above formula (1) to generate a calculation table representing the relationship between the slope A1 of the approximate straight line and the self-discharge current Ipr. Then, the generated calculation table can be pre-recorded in the controller 50. In this case, when the slope A1 of the approximate straight line is obtained, the controller 50 refers to the calculation table and calculates the self-discharge current Ipr that is related to the slope A1 of the obtained approximate straight line.

[0188] Furthermore, as described above, the discharge resistance Rpr of the energy storage device 10 is calculated by dividing the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr. Therefore, if the open-circuit voltage (OCV) of the energy storage device 10 is known, an operation table representing the relationship between the slope A1 of an approximate straight line and the discharge resistance Rpr can be generated and pre-stored in the controller 50. In this case, when the slope A1 of the approximate straight line of voltage change of the energy storage device 10 is obtained, the controller 50 refers to the operation table and calculates the discharge resistance Rpr that is related to the slope A1 of the obtained approximate straight line.

[0189] As described above, in this embodiment, the self-discharge current Ipr or discharge resistance Rpr is calculated based on one or more voltage changes of the energy storage device 10 detected in a short period of time, so the controller 50 can estimate the internal state of the energy storage device 10 in a short period of time.

[0190] Next, the effects of the third embodiment will be explained.

[0191] In this embodiment, the controller 50 generates internal information representing the self-discharge current Ipr or discharge resistance Rpr of the energy storage device 10 based on the change in potential difference measured by the voltmeter 40, as information related to the self-discharge state of the energy storage device 10.

[0192] For example, the controller 50 uses the constant current source 20 to supply a first constant current to the energy storage device 10, and after a predetermined time, switches the constant current supplied to the energy storage device 10 to supply a second constant current. Furthermore, the controller 50 obtains the potential difference between the voltage of the energy storage device 10 and the reference voltage from the voltmeter 40 according to the first and second constant currents, and calculates the slopes A1 and A2 of the voltage change of the energy storage device 10 according to each constant current based on the obtained potential difference.

[0193] Then, the controller 50 calculates the self-discharge current Ipr of the energy storage device 10 using formula (4) or formula (7) based on the slopes A1 and A2 of the voltage change of the energy storage device 10, and calculates the discharge resistance Rpr based on the calculated self-discharge current Ipr. The controller 50 outputs the calculated values ​​of the self-discharge current Ipr and the discharge resistance Rpr as internal information of the energy storage device 10 to the display unit 60.

[0194] With this configuration, the resolution of the voltmeter 40 can be improved by measuring the potential difference between the voltage of the energy storage device 10 and the reference voltage. Therefore, similar to the first and second embodiments, the internal information of the energy storage device 10 can be generated in a short time.

[0195] Furthermore, in this embodiment, the controller 50 generates information indicating whether the energy storage device 10 is good or bad based on the change in potential difference measured by the voltmeter 40, as information related to the self-discharge state of the energy storage device 10.

[0196] For example, the controller 50 determines whether the self-discharge current Ipr or discharge resistance Rpr, calculated based on the change in potential difference measured by the voltmeter 40, is within the specified normal range, and outputs the determination result as determination information to the display unit 60.

[0197] Based on this configuration, similar to the internal information of the aforementioned energy storage device 10, determination information for the energy storage device 10 can be generated in a short time.

[0198] In this embodiment, the controller 50 generates information related to the self-discharge state of the energy storage device 10 based on the change in the potential difference between the voltage of the energy storage device 10 and the reference voltage. Therefore, the state of the energy storage device 10 can be displayed or notified in a short time.

[0199] The above description illustrates this embodiment, but it is only a part of the application examples of the present invention and is not intended to limit the scope of the present invention to the specific configuration of the above embodiment.

[0200] For example, the degree of voltage change in the energy storage device 10 varies depending on the internal temperature of the energy storage device 10. This property can be used to pre-store a temperature gauge representing the relationship between the voltage change and the internal temperature of the energy storage device 10 in the controller 50, which estimates the internal temperature of the energy storage device 10 based on the detected voltage change.

[0201] Furthermore, in the above embodiment, the self-discharge current Ipr and discharge resistance Rpr are calculated using the change in potential difference between the voltage of the energy storage device 10 and the reference voltage. However, the electrostatic capacitance Cst of the energy storage unit 13 can also be calculated. For example, the electrostatic capacitance Cst of the energy storage unit 13 can be calculated by substituting the slope A2 of the voltage change when the energy storage device 10 is charged with a constant current of the second current value I2 and the second current value I2 into the above formula (2).

[0202] In addition, the controller 50 can also determine the internal state of the energy storage device 10 based on the calculated electrostatic capacitance Cst of the energy storage unit 13. For example, the controller 50 determines the condition of the energy storage device 10 by determining whether the calculated value of the electrostatic capacitance Cst is within the specified normal range.

[0203] Furthermore, while the above embodiment measures one energy storage device 10, it is also possible to measure an energy storage device in which multiple energy storage devices 10 are connected in series. Additionally, the measuring device 1 includes a display unit 60, but the display unit 60 may be omitted.

[0204] (Fourth Implementation)

[0205] The measuring apparatus of each of the following embodiments performs processing for detecting voltage changes in the energy storage device 10 based on information representing the electrical characteristics of the energy storage device 10 in an open-circuit state. First, referring to... Figures 8 to 15 The measuring device (hereinafter referred to as "measuring device") 1B of the energy storage device 10 according to the fourth embodiment will be described.

[0206] First, refer to Figure 8 The configuration of the energy storage device 10 and the configuration of the measuring device 1B will be explained. Figure 8 This is a diagram showing the configuration of measuring device 1B.

[0207] The energy storage device 10 is, for example, a single energy storage unit of a lithium-ion secondary battery. The energy storage device 10 is not limited to a secondary battery (chemical battery); it can also be, for example, an electric double-layer capacitor. Furthermore, the energy storage device 10 can also be an energy storage module composed of multiple energy storage units connected in series.

[0208] 10 images of energy storage devices Figure 8 This is represented by an equivalent circuit model. According to the equivalent circuit model, the energy storage device 10 has: a positive electrode 11, a negative electrode 12, an energy storage section 13, an internal resistor 14, and a parallel resistor 15. The energy storage section 13, the internal resistor 14, and the parallel resistor 15 are elements of the equivalent circuit that respectively represent the internal state of the energy storage device 10.

[0209] The energy storage section 13 is the electrostatic capacitance component of the energy storage device 10, which is, for example, around several hundred [F] or several thousand [F]. The energy storage section 13 is charged by accumulating charge when a voltage higher than the unit voltage of the energy storage device 10 is applied. In the energy storage section 13, double-layer reaction mainly occurs when the current flowing during charging is relatively small, and chemical reaction mainly occurs when the current flowing during charging is relatively large. Here, the electrostatic capacitance of the energy storage section 13 is denoted as Cst [F], and the current flowing through the energy storage section 13 is denoted as Ist [A].

[0210] The internal resistor 14 is a series resistor connected in series with the energy storage unit 13 between the positive electrode 11 and the negative electrode 12. Here, the resistance value of the internal resistor 14 is set as Rir [mΩ], and the current flowing through the internal resistor 14 is set as Iir [A].

[0211] The parallel resistor 15 is a discharge resistor connected in parallel with the energy storage unit 13. The current flowing through the parallel resistor 15 is the self-discharge current, also known as the leakage current. Here, the resistance value of the parallel resistor 15 is set as Rpr [kΩ], and the self-discharge current flowing through the parallel resistor 15 is set as Ipr [A].

[0212] The measuring device 1B is a device or system for measuring the state of the energy storage device 10, including a detection device for detecting the time change of the voltage of the energy storage device 10, i.e., voltage change. The measuring device 1B includes: a constant current source 20B as a supply unit, a voltage sensor 40B as a detection unit and a measuring unit, a controller 50B as a calculation unit, and a display unit 60B.

[0213] The constant current source 20B is a DC power supply that charges the energy storage device 10 by providing a constant current to the energy storage device 10 for detecting the internal state of the energy storage device 10. The constant current source 20B maintains the current supplied to the energy storage device 10 at a specified level. The constant current source 20B charges the energy storage device 10 by providing a constant current at a level that is below the overvoltage and at which the double-layer reaction mainly occurs.

[0214] The constant current supplied from the constant current source 20B to the energy storage device 10 can be set based on the value of the self-discharge current of the energy storage device 10, for example, to 10 [μA]. Hereinafter, such a constant current will also be referred to as "micro constant current", and charging by supplying a constant current will also be referred to as "micro charging".

[0215] Here, when charging the energy storage device 10 by applying a constant voltage, it is difficult to stably apply a constant voltage to the energy storage device 10 at a level smaller than an overvoltage, where the double-layer reaction mainly occurs. In contrast, it is easy to supply a relatively small current on the order of microamps (μA) using a constant current source 20B. Therefore, in the measuring device 1B, a constant current at a level smaller than an overvoltage, where the double-layer reaction mainly occurs, can be stably supplied to the energy storage device 10 by using a constant current source 20B.

[0216] Voltage sensor 40B is a DC voltmeter that measures the voltage of the energy storage device 10. Voltage sensor 40B outputs an electrical signal, which sequentially displays the measured voltage, to controller 50B. In this embodiment, voltage sensor 40B measures the voltage of energy storage device 10 at least twice, including in a state where a constant current is supplied from constant current source 20B.

[0217] The controller 50B is composed of a microcomputer equipped with a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface). The controller 50B can also be composed of multiple microcomputers. The controller 50B is a control device that controls various actions of the measuring device 1B by reading the program stored in the ROM from the CPU.

[0218] The controller 50B controls the current supply from the constant current source 20B to the energy storage device 10 and uses the voltage sensor 40B to calculate the internal state of the energy storage device 10. That is, the controller 50B calculates the internal state of the energy storage device 10 based on the electrical signal representing the voltage measured by the voltage sensor 40B.

[0219] In this embodiment, the controller 50B acquires an electrical signal from the voltage sensor 40B while the energy storage device 10 is supplied with a constant current from the constant current source 20B, and detects the time change of the voltage of the energy storage device 10 indicated by the electrical signal. Based on the detected voltage change of the energy storage device 10, the controller 50B infers the internal state of the energy storage device 10, such as its self-discharge state.

[0220] For example, the controller 50B determines the condition of the internal state of the energy storage device 10 based on the detected voltage change of the energy storage device 10. Alternatively, the controller 50B may also calculate the self-discharge current flowing through the parallel resistor 15, the resistance value of the parallel resistor 15, or the electrostatic capacitance of the energy storage section 13 based on the detected voltage change of the energy storage device 10.

[0221] In this embodiment, if the voltage variation of the energy storage device 10 is within the normal range, the controller 50B determines that the energy storage device 10 is normal. On the other hand, if the voltage variation of the energy storage device 10 is outside the normal range, the controller 50B determines that the energy storage device 10 is abnormal. In this way, the controller 50B determines whether the energy storage device 10 is good or bad.

[0222] The display unit 60B displays information such as the determination or calculation results of the controller 50B to notify the user. The display unit 60B is, for example, a touch screen, configured so that the user can visually confirm the information and operate it.

[0223] Next, the operation of the measuring device 1B of this embodiment will be described with reference to the accompanying drawings.

[0224] Figure 9 This is a flowchart illustrating an example of a measurement method using measuring device 1B to measure the state of energy storage device 10. Figure 9 In the example shown, for instance, the measuring device 1B performs the measurement in an environment where the energy storage device 10 is housed in a constant temperature bath that maintains a fixed ambient temperature, thereby suppressing temperature changes in the energy storage device 10.

[0225] First, when performing the above measurement, the measuring device 1B is connected to the energy storage device 10, and is configured to be able to measure the voltage of the energy storage device 10 by means of the voltage sensor 40B, and to be configured to supply constant current to the energy storage device 10 from the constant current source 20B.

[0226] In step SB1, the controller 50B performs a voltage determination process for the energy storage device 10. In this voltage determination process, the controller 50B determines the voltage (specified voltage) for the energy storage device 10 based on the relationship between the voltage of the energy storage device 10 and the electrostatic capacitance Cst of the energy storage device 10.

[0227] The voltage used for measuring the energy storage device 10 refers to the voltage of the energy storage device 10 when a constant current is supplied to it to measure its state. The voltage used for measuring the energy storage device 10 is a specified value that takes into account the electrostatic capacitance Cst of the energy storage device 10, and is expressed as a voltage value or voltage range.

[0228] The relationship between the voltage of the aforementioned energy storage device 10 and its electrostatic capacitance Cst is determined, for example, based on analytical data, theoretical data, or statistical data such as measured data and simulation results of the energy storage device 10. In this embodiment, the controller 50B uses measured data of the characteristics of the electrostatic capacitance Cst relative to the voltage of the energy storage device 10 to determine the measurement voltage of the energy storage device 10. For this measurement voltage determination process, refer to... Figure 10 As described later.

[0229] In step SB2, the controller 50B causes the voltage sensor 40B to measure the voltage of the energy storage device 10. Consequently, an electrical signal corresponding to the voltage of the energy storage device 10 is input from the voltage sensor 40B to the controller 50B.

[0230] In step SB3, the controller 50B determines whether the voltage of the energy storage device 10, as indicated by the electrical signal, is within a specified range. That is, the controller 50B constitutes a determination unit for determining whether the voltage of the energy storage device 10 is the voltage for measurement, as indicated by the specified value. In step SB3, if the voltage of the energy storage device 10 is determined to be within the specified range, the controller 50B proceeds to step SB4. If the voltage of the energy storage device 10 is determined to be outside the specified range, the controller 50B proceeds to step SB7.

[0231] In step SB7, the controller 50B performs voltage control to adjust the voltage of the energy storage device 10 to the voltage for measurement. In this voltage control, the controller 50B supplies a relatively large current to induce a chemical reaction in the energy storage device 10, thereby charging or discharging the energy storage device 10. This type of charging or discharging will hereinafter be referred to as "normal charging" or "normal discharging".

[0232] In this embodiment, the controller 50B supplies a charging current or discharging current greater than a small constant current to the energy storage device 10 from the constant current source 20B to charge or discharge the energy storage device 10. At this time, the charging current supplied from the constant current source 20B to the positive electrode 11 of the energy storage device 10 is, for example, +190 [mA], and the discharging current supplied from the constant current source 20B to the negative electrode 12 of the energy storage device 10 is, for example, -190 [mA].

[0233] Instead, in the charge-discharge cycle process of the performance test of the energy storage device 10, when the voltage of the energy storage device 10 reaches the measurement voltage, the controller 50B interrupts the process. Alternatively, the voltage of the energy storage device 10 can be adjusted to the measurement voltage.

[0234] When the voltage control is completed in step SB7, the controller 50B returns to step SB2. If it is determined in step SB3 that the voltage of the energy storage device 10 is within the specified range, it proceeds to step SB4.

[0235] In step SB4, the controller 50B supplies a small constant current from the constant current source 20B to the energy storage device 10 to begin a small charge.

[0236] In step SB5, voltage sensor 40B measures the voltage of energy storage device 10 under a slight charging state. Therefore, controller 50B can obtain an electrical signal from voltage sensor 40B representing the voltage of energy storage device 10 supplied with a constant current as measurement data.

[0237] In step SB6, the controller 50B performs state calculation processing on the energy storage device 10. In this state calculation processing, the controller 50B calculates the internal state of the energy storage device 10 based on the voltage of the energy storage device 10 as indicated by an electrical signal. For this state calculation processing, refer to... Figure 13 This will be discussed in detail later.

[0238] When step SB6 is completed, the series of processing steps for the measurement method of measuring device 1B ends.

[0239] Next, refer to Figure 10 The voltage determination process performed in step SB1 will be explained. Figure 10 This is a flowchart illustrating an example of the voltage determination process (SB1) for measuring device 1B.

[0240] In step SB11, the controller 50B causes the voltage sensor 40B to measure the voltage of the energy storage device 10. Consequently, an electrical signal corresponding to the voltage of the energy storage device 10 is input from the voltage sensor 40B to the controller 50B.

[0241] In step SB12, the controller 50B performs charge / discharge control to charge or discharge the energy storage device 10 in a manner that induces a chemical reaction in the energy storage device 10. In this embodiment, the controller 50B performs both charge control (supplying a charging current to the energy storage device 10 for normal charging) and discharge control (supplying a discharging current to the energy storage device 10 for normal discharging) at least once. The absolute values ​​of the discharge current and the charging current are set to tens of thousands of times the magnitude of a constant current.

[0242] In step SB13, voltage sensor 40B measures the voltage of the energy storage device 10 during charge / discharge control. Therefore, controller 50B can acquire an electrical signal from voltage sensor 40B representing the voltage of the energy storage device 10 during charge / discharge control as measurement data. This electrical signal is used as measurement data relating the electrostatic capacitance Cst of a specific energy storage device 10 to the voltage of the energy storage device 10.

[0243] In step SB14, the controller 50B generates characteristic data representing the relationship between the electrostatic capacitance Cst of the energy storage device 10 and the voltage of the energy storage device 10 based on the electrical signal obtained from the voltage sensor 40B.

[0244] In this embodiment, the controller 50B calculates the electrostatic capacitance Cst of the energy storage device 10 by multiplying the charging current Ic or discharging current Id (which is the current I) by the time change dt per unit voltage dV for each voltage value of the energy storage device 10, as shown in the following formula (8). The controller 50B generates the aforementioned characteristic data in this way. This characteristic data is recorded in the memory of the controller 50B.

[0245] [Formula 8]

[0246]

[0247] Instead, the controller 50B calculates the voltage change per unit time, i.e., the slope of the voltage change of the energy storage device 10, for each voltage value of the energy storage device 10. Alternatively, it can generate characteristic data representing the relationship between the voltage of the energy storage device 10 and the slope of the voltage change. In this case, as the electrostatic capacitance Cst of the energy storage device 10 decreases, the slope of the voltage change of the energy storage device 10 increases.

[0248] In step SB15, the controller 50B determines the measurement voltage of the energy storage device 10 based on the generated characteristic data.

[0249] In this embodiment, the controller 50B determines the voltage value for measuring the energy storage device 10 as a voltage value where the electrostatic capacitance Cst of the energy storage device 10 is below a threshold value less than its maximum value. That is, the controller 50B determines the voltage value for measuring the energy storage device 10 in a manner that avoids the electrostatic capacitance Cst of the energy storage device 10 being near its maximum voltage value.

[0250] Therefore, the electrostatic capacitance Cst of the energy storage device 10 is less than its maximum value, thus enabling the voltage change of the energy storage device 10 to be larger when a small constant current is supplied to it. For example, the above threshold can be set based on the maximum or average value of the electrostatic capacitance Cst of the energy storage device 10.

[0251] When step SB15 is completed, the series of processing steps related to the voltage determination process in this embodiment ends, and controller 50B returns. Figure 9 The processing flow of the measurement method shown proceeds to step SB2.

[0252] Here, refer to Figure 11 and Figure 12 Specific examples of the processing steps SB13 to SB15 are explained. Figure 11This is a graph illustrating the change in voltage of the energy storage device 10 over time relative to the time elapsed when charge and discharge control is performed on the energy storage device 10. Figure 12 This is a graph illustrating the relationship between the voltage of the energy storage device 10 and the electrostatic capacitance Cst.

[0253] exist Figure 11 In the example shown, after charging control of the energy storage device 10 with a charging current Ic of +190 [mA], discharging control of the energy storage device 10 with a discharging current Id of -190 [mA] is performed, and the voltage change of the energy storage device 10 at this time is shown. Here, the horizontal axis represents the elapsed time since the start of charging and discharging control of the energy storage device 10, and the vertical axis represents the voltage of the energy storage device 10.

[0254] Figure 11 The solid line shown is based on the measurement data obtained through the processing in step SB13. The fully discharged voltage Vl of the energy storage device 10 when its charging capacity is 0% is approximately 3.0 [V], and the fully charged voltage Vu of the energy storage device 10 when its charging capacity is 100% is approximately 4.2 [V]. Thus, during charge and discharge control, the voltage of the energy storage device 10 varies within the range from the fully discharged voltage Vl to the fully charged voltage Vu.

[0255] like Figure 11 As shown, within the voltage range of 3.0V to 3.5V for the energy storage device 10, the slope of the solid line is large, therefore it can be said that the electrostatic capacitance Cst of the energy storage device 10 is small. Within the voltage range of 3.5V to 3.7V, the slope of the solid line is small, therefore it can be said that the electrostatic capacitance Cst of the energy storage device 10 is large.

[0256] In this way, by acquiring measurement data representing the voltage change of the energy storage device 10 during charge-discharge control, the voltage value of the energy storage device 10 with a relatively large electrostatic capacitance Cst can be determined. Therefore, this measurement data can be used as characteristic data for the characteristics of the electrostatic capacitance Cst relative to the voltage of the energy storage device 10.

[0257] Next, the relationship between the voltage of the energy storage device 10 and the electrostatic capacitance Cst of the energy storage device 10 will be explained in more detail.

[0258] Figure 12 The horizontal axis represents the voltage of the energy storage device 10, and the vertical axis represents the electrostatic capacitance Cst of the energy storage device 10. The electrostatic capacitance Cst of the energy storage device 10 is calculated as in the above formula (8).

[0259] Figure 12The solid line shown represents the voltage-capacitance characteristics of the energy storage device 10, depicted based on the characteristic data generated by the processing in step SB14. A positive value represents the electrostatic capacitance Cst during charging control, while a negative value represents the electrostatic capacitance Cst during discharging control for convenience; both have the same voltage-capacitance characteristics. The following explanation focuses on the voltage-capacitance characteristics during charging control.

[0260] like Figure 12 As shown, the electrostatic capacitance Cst of the energy storage device 10 is extremely large when the voltage of the energy storage device 10 is about 3.4 [V] and about 3.7 [V], and the electrostatic capacitance Cst is the largest when the voltage is about 3.7 [V].

[0261] In this embodiment, when measuring the internal state of the energy storage device 10, it is necessary to determine the voltage change of the energy storage device 10 when a small constant current is supplied to it. Regarding the voltage change of the energy storage device 10, the larger the electrostatic capacitance Cst of the energy storage device 10, the smaller the degree of voltage change; therefore, measuring the voltage change requires time.

[0262] As a countermeasure, the following steps shall be taken. Figure 10 The process shown in step SB15. That is, the controller 50B determines the measurement voltage of the energy storage device 10 in a manner that avoids the voltage value of the energy storage device 10 corresponding to the maximum point B where the electrostatic capacitance Cst of the energy storage device 10 is the largest and the vicinity therein.

[0263] Specifically, the voltage used for measuring the energy storage device 10 is set to a voltage value at which the electrostatic capacitance Cst of the energy storage device 10 is lower than a predetermined threshold Th. For example, the threshold Th is determined based on the maximum value of the electrostatic capacitance Cst, and in this embodiment, it is set to half the maximum value of the electrostatic capacitance Cst. Alternatively, the threshold Th can also be determined based on the average value of the electrostatic capacitance Cst.

[0264] Furthermore, when the energy storage device 10 is a lithium-ion secondary battery, the closer the voltage of the energy storage device 10 is to the full charge voltage Vu, the easier it is for a decomposition reaction to occur within the energy storage device 10. Therefore, from the viewpoint of suppressing the deterioration of the energy storage device 10, the voltage used for measuring the energy storage device 10 is preferably set to a voltage value lower than the specific voltage value at which the electrostatic capacitance Cst of the energy storage device 10 reaches its maximum. Thus, the controller 50B can ensure that the voltage used for measuring the energy storage device 10 is lower than the specific voltage value at which the electrostatic capacitance Cst of the energy storage device 10 reaches its maximum.

[0265] In this embodiment, the controller 50B determines the voltage value of the energy storage device 10, which corresponds to the minimum point A where the electrostatic capacitance Cst of the energy storage device 10 is minimized, i.e., the voltage value near the complete discharge voltage Vl, as the measurement voltage of the energy storage device 10. This maximizes the voltage change during the minute charging of the energy storage device 10.

[0266] Instead, the controller 50B determines the voltage value of the energy storage device 10 to be the minimum point C corresponding to the minimum capacitance Cst of the energy storage device 10. Therefore, voltage changes in the energy storage device 10 can be quickly detected even when the energy storage device 10 is in a stable state.

[0267] Subsequently, in step SB3, the controller 50B determines whether the voltage of the energy storage device 10 is within a specified range for measurement. That is, the controller 50B determines whether the electrostatic capacitance Cst of the energy storage device 10 exceeds a threshold based on the voltage of the energy storage device 10.

[0268] Next, refer to Figures 13 to 15 For Figure 9 The state operation processing performed in step SB6 is explained below.

[0269] Figure 13 This is a flowchart illustrating an example of the state calculation processing (SB6) of the measuring device 1B. Figure 14 This is a diagram illustrating an example of voltage variation in the energy storage device 10 relative to the small constant current supply time in this embodiment. Figure 15 This is a diagram illustrating, as a comparative example, the voltage change of the energy storage device 10 when the electrostatic capacitor Cst becomes the largest specific voltage value relative to the supply time of a small constant current.

[0270] exist Figure 13 In the example shown, as a state operation process (SB6), the controller 50B determines the condition of the energy storage device 10 based on the voltage change of the energy storage device 10.

[0271] In step SB61, the controller 50B determines whether the supply time, which is the elapsed time from the start of supplying a small constant current to the energy storage device 10, has exceeded a predetermined time. The predetermined time is preset to be the length of time during which the voltage change of the energy storage device 10 differs between normal and abnormal conditions.

[0272] In step SB61, if it is determined that the constant current supply time has not exceeded the predetermined time, the controller 50B continues to supply a small constant current to the energy storage device 10 until it is determined that the supply time has exceeded the predetermined time. On the other hand, if it is determined that the supply time has exceeded the predetermined time, the controller 50B moves to step SB62.

[0273] In this way, voltage sensor 40B measures the initial voltage as the voltage at the start of constant current supply and the minute charging voltage in the state where constant current is supplied from constant current source 20B. That is, voltage sensor 40B measures the voltage of energy storage device 10 more than twice, including the state where constant current is supplied from constant current source 20B.

[0274] In step SB62, the controller 50B detects the voltage change of the energy storage device 10 based on the voltage measured by the voltage sensor 40B. Specifically, the controller 50B calculates an approximate linear relationship between the voltage change of the energy storage device 10 and the initial voltage at the start of the supply and the small charging voltage under constant current conditions supplied from the constant current source 20B. More specifically, the controller 50B calculates the approximate linear relationship between the voltage change of the energy storage device 10 using the least squares method based on the small charging voltage measured in each control cycle.

[0275] Alternatively, the controller 50B can also be configured to detect the voltage change of the energy storage device 10 based on the difference between the initial voltage at the start of supply and the supply voltage under constant current conditions supplied from the constant current source 20B. In this case, it is sufficient to measure the voltage of the energy storage device 10 twice using the voltage sensor 40B, and therefore, a multiplexer can be used for switching to perform the voltage measurement. This simplifies the measuring device 1B.

[0276] In step SB63, it is determined whether the slope of the approximate straight line is within a specified range. If the slope of the approximate straight line is determined to be within the specified range between the upper and lower limits, the energy storage device 10 is in a normal state, and the process proceeds to step SB64. On the other hand, if the slope of the approximate straight line is determined to be outside the specified range in step SB63, i.e., greater than the upper limit of the specified range or less than the lower limit of the specified range, the energy storage device 10 is in an abnormal state, and the process proceeds to step SB65.

[0277] In step SB64, assuming the energy storage device 10 is in a normal state, the controller 50B displays its message on the display unit 60B to notify the user. On the other hand, in step SB65, assuming the energy storage device 10 is in an abnormal state, the controller 50B displays its message on the display unit 60B to notify the user.

[0278] The condition of the energy storage device 10 is determined by performing the above state operation processing (SB6).

[0279] Next, refer to Figure 14 and Figure 15 Specific examples of the processing in steps SB62 and SB63 are explained. Figure 14 and Figure 15The horizontal axis represents the supply time [s], which is the elapsed time from the start of supplying a small constant current to the energy storage device 10, and the vertical axis represents the difference [μV] between the small charging voltage measured by the voltage sensor 40B and the initial voltage.

[0280] exist Figure 14 In the example shown, the initial voltage at the start of the supply is equal to... Figure 12 The voltage value corresponding to the minimum point A shown indicates the measured data when the electrostatic capacitance Cst of the energy storage device 10 is at its minimum.

[0281] Figure 14 The solid line shown represents the voltage change when the energy storage device 10 is in normal operation. The straight line of the solid line is an approximate straight line Ln1B of the voltage change obtained through the processing in step SB62. On the other hand, Figure 14 The dashed line data represents the voltage change when the energy storage device 10 is in an abnormal state. The straight line of the dashed line is an approximate straight line La1B of the voltage change obtained through the processing in step SB62. Furthermore, the slope of the approximate straight line Ln1B is set as Rn, and the slope of the approximate straight line La1B is set as Ra.

[0282] also, Figure 14 The two double-dotted lines shown represent the upper limit Rmax and lower limit Rmin of the slope of the approximate straight line, respectively. The slope between the two double-dotted lines represents the slope of the energy storage device 10 under normal conditions. It should be noted that the upper limit Rmax and lower limit Rmin of the slope of the approximate straight line are set to, for example, ±10% of the approximate straight line obtained by prior measurement using the energy storage device 10 under normal conditions.

[0283] Reference Figure 14 The approximate straight line Ln1B (slope Rn), represented by a solid line, lies between the upper limit Rmax and the lower limit Rmin of the slope of the approximate straight line. Therefore, the controller 50B determines that the energy storage device 10 is in a normal state. On the other hand, the approximate straight line La1B (slope Ra), represented by a dashed line, does not lie between the upper limit Rmax and the lower limit Rmin of the slope of the approximate straight line. Therefore, the controller 50B determines that the energy storage device 10 is in an abnormal state.

[0284] In this way, the controller 50B determines whether the energy storage device 10 is in a normal state or an abnormal state based on whether the slope of the approximate straight line is between the upper limit value Rmax and the lower limit value Rmin.

[0285] It should be noted that, in Figure 14In the example shown, the determination of the quality of the energy storage device 10 took 600 seconds (TB1), but the difference in slope between the approximate straight line Ln1B (represented by the solid line) and the approximate straight line La1B (represented by the dashed line) could be clearly confirmed after only about 100 seconds of supply time. In this way, the determination of the quality of the energy storage device 10 can be performed in a short time of about a few minutes in the measuring device 1B.

[0286] On the other hand, Figure 15 In the example shown, the initial voltage at the start of the supply is equal to... Figure 12 The voltage value corresponding to the maximum point B shown represents the measured data when the electrostatic capacitance Cst of the energy storage device 10 is at its maximum. The solid line represents the voltage change when the energy storage device 10 is in a normal state, and the straight line of the solid line is the approximate straight line Ln0B of the voltage change obtained through the processing in step SB62.

[0287] like Figure 15 As shown, the slope of the approximate straight line Ln0B, represented by the solid line, is approximately zero during the measurement time TB1 of 600 [s], making it difficult to determine whether the device is good or bad. Therefore, when the electrostatic capacitance Cst of the energy storage device 10 is relatively large, the time for determining whether the device is good or bad must be extended.

[0288] As described above, the measuring device 1B of this embodiment charges the energy storage device 10 with a small constant current from the constant current source 20B, measures the small charging voltage under constant current conditions, and thus detects the voltage change of the energy storage device 10. It then determines whether the detected voltage change of the energy storage device 10 is within the normal range; if the voltage change is within the normal range, the energy storage device 10 is determined to be normal. Therefore, there is no need to wait for the voltage of the energy storage device 10 to decrease due to self-discharge, thus the time spent determining the condition of the energy storage device 10 is short.

[0289] At this time, the constant current source 20B supplies a constant current, smaller than the overvoltage, to the energy storage device 10 to charge the device 10, where the double-layer reaction mainly occurs. Therefore, the magnitude of the constant current is relatively small, resulting in a large ratio between the current Ist[A] flowing through the energy storage section 13 and the current Ipr[A] flowing through the parallel resistor 15. Consequently, the difference in the slope of the small charging curve caused by the presence or absence of the parallel resistor 15 becomes larger, making it easier to determine whether the energy storage device 10 is functioning correctly.

[0290] In addition, the measuring device 1B determines the measuring voltage based on the characteristics of the electrostatic capacitance Cst relative to the voltage of the energy storage device 10, in a manner that avoids the maximum value of the electrostatic capacitance Cst of the energy storage device 10. Then, the measuring device 1B performs a small charge when the voltage of the energy storage device 10 becomes the measuring voltage. Therefore, the reduction of voltage change caused by the electrostatic capacitance Cst of the energy storage device 10 is suppressed.

[0291] Therefore, the quality of the energy storage device 10 can be determined in a short time.

[0292] It should be noted that in the above embodiment, the voltage sensor 40B measures the voltage of the energy storage device 10 as the initial voltage after a small constant current is supplied. However, alternatively, the voltage sensor 40B can also measure the voltage of the energy storage device 10 as the initial voltage before a small constant current is supplied. In this case, the voltage of the energy storage device 10 can be measured more than twice, including the state where a constant current is supplied, thus allowing an approximate linear change in the voltage of the energy storage device 10 to be obtained.

[0293] Next, the effects of the fourth embodiment will be explained.

[0294] The measuring device 1B in this embodiment constitutes a device for detecting voltage changes in the energy storage device 10. The measuring device 1B includes: a constant current source 20B (supply unit) that supplies a constant current to the energy storage device 10; and a voltage sensor 40B (measuring unit) that measures the voltage associated with the energy storage device 10 to which a constant current is supplied. The measuring device 1B also includes a controller 50B (processing unit) that detects the measured voltage changes in the energy storage device 10. The measuring device 1B then acquires the voltage changes of the energy storage device 10 based on electrical characteristics that serve as a reference for the energy storage device 10.

[0295] Furthermore, regarding the method for detecting voltage changes in the energy storage device 10 in this embodiment, a constant current is supplied to the energy storage device 10, and the voltage associated with the energy storage device 10 to which the constant current is supplied is measured, and the measured voltage change of the energy storage device is detected. This method obtains the voltage change of the energy storage device 10, which varies according to the magnitude of the self-discharge current or discharge resistance of the energy storage device 10, based on the electrical characteristics that serve as a reference for the energy storage device 10.

[0296] The aforementioned electrical characteristics that serve as the reference for the energy storage device 10 refer to the electrical characteristics of the energy storage device 10 in the open-circuit state, including the relationship between the output voltage of the energy storage device 10 in the open-circuit state and the electrostatic capacitance Cst, as well as the variation of the open-circuit voltage of the energy storage device 10.

[0297] In this embodiment, the measuring device 1B performs processing for detecting voltage changes in the energy storage device 10 based on information representing its electrical characteristics in the open-circuit state. Specifically, the controller 50B determines whether the voltage of the energy storage device 10 has become a measuring voltage (specified voltage) based on the relationship between the output voltage and the capacitance Cst in the open-circuit state of the energy storage device 10. Then, if the voltage of the energy storage device 10 has become the measuring voltage, the controller 50B supplies a constant current from the constant current source 20B to the energy storage device 10, thereby acquiring the voltage change of the energy storage device 10. More specifically, as shown below.

[0298] The method for measuring the state of the energy storage device 10 in this embodiment includes a determination step (SB1) that determines a measuring voltage representing the voltage value when measuring the state of the energy storage device 10 based on the relationship between the voltage of the energy storage device 10 and the electrostatic capacitance Cst of the energy storage device 10. Furthermore, the method includes a supply step (SB4) that supplies a constant current to the energy storage device 10 when the voltage of the energy storage device 10 is the aforementioned measuring voltage; and a measurement step (SB5) that measures the voltage of the energy storage device 10 supplied with the constant current. In addition, the method includes a calculation step (SB6) that calculates the internal state of the energy storage device 10 based on the measured voltage change of the energy storage device 10.

[0299] Then, the measuring device 1B in this embodiment, which includes a detection device for detecting voltage changes in the energy storage device 10, includes a constant current source 20B that supplies a constant current to the energy storage device 10 when the voltage of the energy storage device 10 is a predetermined value. Furthermore, the measuring device 1B includes: a voltage sensor 40B that measures the voltage of the energy storage device 10 to which a constant current is supplied; and a controller 50B that detects voltage changes in the energy storage device 10 based on the measured voltage. The predetermined value is determined based on data relating the voltage of a specific energy storage device 10 to its electrostatic capacitance Cst. It should be noted that the relationship between the voltage and electrostatic capacitance Cst in the energy storage device 10 is included in the electrical characteristics that serve as a reference for the energy storage device 10. Therefore, the predetermined value is a voltage value based on the electrical characteristics that serve as a reference for the energy storage device 10.

[0300] Furthermore, the measuring device 1B for measuring the state of the energy storage device 10 in this embodiment includes the aforementioned constant current source 20B, voltage sensor 40B, and controller 50B. In addition, the controller 50B calculates the internal state of the energy storage device 10 based on the measured voltage changes of the energy storage device 10.

[0301] First, the different internal states of the energy storage device 10 are manifested in the different time changes of the voltage of the energy storage device 10. Therefore, according to the above configuration, the voltage change of the energy storage device 10 can be increased by supplying a constant current to the energy storage device 10. Therefore, the time required to determine the voltage change and internal state of the energy storage device 10 can be shortened.

[0302] In addition, based on the above configuration, the measuring voltage is determined to a predetermined value considering the relationship between the voltage of the energy storage device 10 and the electrostatic capacitance Cst of the energy storage device 10. As a result, a constant current can be supplied to the energy storage device 10 when the electrostatic capacitance Cst of the energy storage device 10 is relatively small, thus enabling a larger voltage change in the energy storage device 10.

[0303] In this way, the electrostatic capacitance Cst of the energy storage device 10 can be taken into account to increase the voltage change of the energy storage device 10, so the state of the energy storage device 10 can be determined in a short time.

[0304] Furthermore, based on the above configuration, it is easier to supply a smaller current using the constant current source 20B compared to supplying a constant voltage to the energy storage device 10. Therefore, in the measuring device 1B, a constant current of a magnitude smaller than the overvoltage, in which the double-layer reaction mainly occurs, can be stably supplied to the energy storage device 10 by using the constant current source 20B.

[0305] Furthermore, in this embodiment, the controller 50B of the measuring device 1B determines the measuring voltage in a manner that avoids a specific voltage value near which the electrostatic capacitance Cst of the energy storage device 10 is at its maximum within the range of voltage changes caused by normal discharge or charging. For example, the measuring voltage is set to a voltage value where the electrostatic capacitance component of the energy storage device 10 is below a threshold value within the range of voltage changes caused by discharge or charging. The threshold value is set based on the maximum or average value of the electrostatic capacitance Cst of the energy storage device 10.

[0306] According to this configuration, a constant current is supplied to the energy storage device 10 when the electrostatic capacitance Cst of the energy storage device 10 is less than its maximum value (upper limit). As a result, compared with the case where the energy storage device 10 is performing a small charge when the electrostatic capacitance Cst of the energy storage device 10 is at its maximum, the voltage change of the energy storage device 10 can be increased.

[0307] Furthermore, in this embodiment, the controller 50B sets the voltage for measuring the energy storage device 10 to a specific value that is lower than the maximum capacitance Cst of the energy storage device 10. As a result, decomposition reactions that occur in the energy storage device 10 are less likely to occur, thus increasing the voltage variation of the energy storage device 10 and suppressing the deterioration of the energy storage device 10.

[0308] Furthermore, in this embodiment, the controller 50B performs: a control step (SB12) to control the charging or discharging of the energy storage device 10; and a control measurement step (SB13) to measure the voltage of the energy storage device 10 during the control process. Moreover, the controller 50B performs a generation step (SB14) to generate data on the relationship between the voltage of a specific energy storage device 10 and its electrostatic capacitance Cst, based on the measured voltage of the energy storage device 10.

[0309] Based on this configuration, the voltage for measuring the energy storage device 10 is determined based on the measured data of the energy storage device 10, thus accurately avoiding the maximum specific voltage value of the electrostatic capacitance Cst of the energy storage device 10.

[0310] Furthermore, in this embodiment, the constant current source 20B supplies a constant current to the energy storage device 10 that is less than the overvoltage and at which the double-layer reaction mainly occurs.

[0311] Because of this configuration, the magnitude of the constant current is small, so the ratio of the current Ist[A] flowing through the energy storage unit 13 to the current Ipr[A] flowing through the parallel resistor 15 becomes larger. Therefore, the difference in the slope of the small charging curve caused by the presence or absence of the parallel resistor 15 becomes larger, making it easier to determine whether the energy storage device 10 is functioning properly.

[0312] <Variation Example>

[0313] Next, the controller 50B of the measuring apparatus 1B in the modified example of the fourth embodiment will be described. In this modified example, the controller 50B determines the measuring voltage based on the measuring conditions of the energy storage device 10, which differs from the embodiments described above.

[0314] In this modified example, the controller 50B is set based on the measurement time TB1 for measuring the voltage of the energy storage device 10 or the amount of voltage change ΔV required for detecting the voltage change. Figure 12 The threshold Th associated with the electrostatic capacitance Cst is shown. Here, the voltage change ΔV refers to the change from the initial voltage over the measurement time TB1.

[0315] For example, when different measuring devices 1B have different measuring times TB1 or voltage changes ΔV, the controller 50B calculates the upper limit of the electrostatic capacitance Cst that can detect voltage changes based on the predetermined measuring time TB1 and voltage change ΔV. Specifically, the controller 50B uses the above formula (8) to substitute the value of the measuring time TB1 into dt and the value of the voltage change ΔV into dt, thereby calculating the upper limit of the electrostatic capacitance Cst.

[0316] The controller 50B then sets the calculated upper limit of the electrostatic capacitance Cst as the threshold Th. In other words, the threshold Th is set based on the measurement time TB1 or the voltage change ΔV. Thus, the controller 50B can determine the voltage value lower than the calculated upper limit of the electrostatic capacitance Cst as the measurement voltage.

[0317] In this way, the controller 50B determines the measurement voltage of the energy storage device 10 based on the measurement time TB1 or the voltage change ΔV.

[0318] Furthermore, when the measurement time TB1 is variable, the controller 50B can also set the measurement time TB1 based on the current value of the voltage of the energy storage device 10. In this case, when the voltage of the energy storage device 10 is obtained from the voltage sensor 40B, the controller 50B refers to... Figure 12 The characteristic data shown is used to calculate the electrostatic capacitance Cst corresponding to the acquired voltage. Then, the controller 50B substitutes the calculated electrostatic capacitance Cst and the predetermined voltage change ΔV into equation (8) to calculate the value of the measurement time TB1. The same applies to the case where the voltage change ΔV is variable.

[0319] According to a variation of the fourth embodiment, the controller 50B determines the measurement voltage of the energy storage device 10 based on the measurement time TB1 for detecting the voltage change of the energy storage device 10 supplied with constant current or the amount of voltage change ΔV required for detection. Therefore, a small charge is performed while the electrostatic capacitance Cst of the energy storage device 10 does not exceed the upper limit, thus ensuring the measurement accuracy of the energy storage device 10.

[0320] (Fifth Implementation)

[0321] Next, the controller 50B of the measuring device 1B in the fifth embodiment will be described. Hereinafter, the resistance value of the parallel resistor 15 will be referred to as the discharge resistor Rpr, and the current flowing through the parallel resistor 15 will be referred to as the self-discharge current Ipr.

[0322] In the case of the controller 50B in this embodiment, the calculation of the discharge resistance Rpr or self-discharge current Ipr of the energy storage device 10 differs from that in the fourth embodiment.

[0323] The controller 50B switches the constant current supplied from the constant current source 20B to the energy storage device 10 between a constant current showing a first current value and a constant current showing a second current value. Hereinafter, the constant current showing the first current value will also be referred to as the "first constant current", and the constant current showing the second current value will also be referred to as the "second constant current".

[0324] The first current value is set similarly to that in the fourth embodiment, to be one or several times the reference value of the self-discharge current Ipr of the energy storage device 10. In this embodiment, it is set to 10 [μA] times the reference value of the self-discharge current Ipr. Furthermore, the second current value is set to several tens of times or more the reference value of the self-discharge current Ipr of the energy storage device 10. In this embodiment, it is set to fifty times the reference value of the self-discharge current Ipr.

[0325] The aforementioned reference value for the self-discharge current Ipr is known information. For example, the reference value for the self-discharge current Ipr can be predetermined using statistical data summarizing the self-discharge currents Ipr of multiple energy storage devices 10 or test results of the self-discharge current Ipr of a specific energy storage device 10 with normal electrical characteristics.

[0326] Next, the controller 50B detects the voltage change of the energy storage device 10 based on the voltage of the energy storage device 10, according to the magnitude of the constant current supplied from the constant current source 20B.

[0327] In this embodiment, such as Figure 14 As shown, for each constant current, the controller 50B calculates the slope of the voltage change of the energy storage device 10 based on the initial voltage when the constant current is supplied and the small charging voltage under the condition that the constant current is supplied from the constant current source 20B. Alternatively, the controller 50B can also calculate an approximate straight line Ln1B of the voltage change of the energy storage device 10 according to the magnitude of each constant current supplied to the energy storage device 10, and use the slope of this approximate straight line Ln1B as the slope of the voltage change.

[0328] The controller 50B calculates the self-discharge current Ipr of the energy storage device 10 using the slope of the voltage change of the energy storage device 10 calculated according to the magnitude of each constant current and the formula for calculating the electrostatic capacitance Cst of the energy storage section 13 of the energy storage device 10. Here, the calculation method of the self-discharge current Ipr of the energy storage device 10 will be explained.

[0329] The formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the slope A1 of the voltage change during charging of the energy storage device 10 with a constant current of the first current value I1, and the charging current Ist[A] of the energy storage unit 13. The charging current Ist[A] of the energy storage unit 13 is the amount of charge stored in the electrostatic capacitance Cst per unit time. The charging current Ist[A] of the energy storage unit 13 is equivalent to the charge flowing from the electrostatic capacitance Cst through the energy storage device 10. Figure 8 The value (I1 - Ipr) is obtained by subtracting the self-discharge current Ipr flowing through the parallel resistor 15 from the first current value I1 of the internal resistor 14 shown.

[0330] Therefore, the formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10, the first current value I1, and the slope A1 of the voltage change when the energy storage device 10 is charged with the first constant current. The formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 is shown in the following formula (9).

[0331] [Formula 9]

[0332]

[0333] Furthermore, the formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the second current value I2 and the slope A2 of the voltage change when the constant current of the second current value I2 is charging the energy storage device 10, as shown in the following formula (10).

[0334] [Formula 10]

[0335]

[0336] In the above formula (10), the charging current Ist[A] of the electrostatic capacitor Cst is equivalent to the value (I2 - Ipr) obtained by subtracting the self-discharge current Ipr from the current value I2 of the second constant current. However, as the current flowing through... Figure 8 The current value I2 of the second constant current of the internal resistor 14 shown is sufficiently greater than the self-discharge current Ipr flowing through the parallel resistor 15 as described above, and can therefore be approximated as in the following formula (11).

[0337] [Formula 11]

[0338] I2≈(I2-I pr )···(11)

[0339] Therefore, in the above formula (10), the current value I2 of the second constant current is used instead of the current value (I2-Ipr) obtained by subtracting the self-discharge current Ipr from the current value I2 of the second constant current. Next, if the self-discharge current Ipr is solved using formulas (9) and (10), the following formula (12) is derived.

[0340] [Formula 12]

[0341]

[0342] In this way, the self-discharge current Ipr of the energy storage device 10 can be calculated by substituting the slopes A1 and A2 of the voltage change obtained according to the magnitude of each constant current and the current values ​​I1 and I2 of the constant current into the formula for calculating the electrostatic capacitance Cst of the energy storage section 13.

[0343] Next, the controller 50B calculates the discharge resistance Rpr of the energy storage device 10 based on the calculated self-discharge current Ipr.

[0344] In this embodiment, the controller 50B calculates the discharge resistance Rpr of the energy storage device 10 by dividing the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr of the energy storage device 10. The open-circuit voltage (OCV) of the energy storage device 10 can be the voltage value of the energy storage device 10 measured by the voltage sensor 40B before the constant current supply begins, or it can be a voltage value predetermined by using test results of the energy storage device 10, etc.

[0345] Instead, the controller 50B can also pre-store a correspondence table or function representing the relationship between the self-discharge current Ipr and the discharge resistance Rpr of the energy storage device 10, and use the correspondence table or function to calculate the discharge resistance Rpr.

[0346] Finally, the controller 50B determines whether the energy storage device 10 is normal based on the calculated discharge resistance Rpr.

[0347] In this embodiment, the controller 50B determines whether the calculated value of the discharge resistance Rpr of the energy storage device 10 is within a specified resistance range. The upper and lower limits of the specified resistance range are predetermined using statistical data summarizing the discharge resistances Rpr of multiple energy storage devices 10 or test results of a specific energy storage device 10 with normal electrical characteristics.

[0348] Then, if the calculated value of the discharge resistor Rpr is within the specified resistance range, the controller 50B determines that the energy storage device 10 is in a normal state. Conversely, if the calculated value of the discharge resistor Rpr is outside the specified range, the controller 50B determines that the energy storage device 10 is malfunctioning.

[0349] Alternatively, a diagnostic table representing the normal or abnormal state of the energy storage device 10 for each discharge resistance Rpr can be pre-stored in the controller 50B. In this case, when the discharge resistance Rpr of the energy storage device 10 is calculated, the controller 50B refers to the diagnostic table and establishes a specific internal state of the energy storage device 10 corresponding to the calculated discharge resistance Rpr.

[0350] It should be noted that in this embodiment, the controller 50B determines the condition of the energy storage device 10 based on the calculated value of the discharge resistance Rpr. However, alternatively, the calculated value of the self-discharge current Ipr can also be used to determine whether the energy storage device 10 is in a normal state. In this case, the controller 50B determines, for example, whether the calculated value of the self-discharge current Ipr is within a specified current range. When it is determined that the calculated value is within the specified current range, the energy storage device 10 is determined to be in a normal state.

[0351] Furthermore, in this embodiment, the controller 50B controls the operation of the constant current source 20B by sequentially supplying constant currents with different current values ​​to the energy storage device 10. However, if the electrostatic capacitance Cst of the energy storage unit 13 is known, it is also possible to supply only the constant current showing the first current value I1. In this case, the electrostatic capacitance Cst of the energy storage unit 13 is pre-stored in the controller 50B. Then, the controller 50B substitutes the electrostatic capacitance Cst of the energy storage unit 13, the first current value I1, and the slope A1 of the voltage change corresponding to the first current value I1 into the above formula (9) to calculate the self-discharge current Ipr.

[0352] Regarding the electrostatic capacitance Cst stored in the controller 50B, it can be predetermined using statistical data summarizing the electrostatic capacitance Cst of the energy storage units 13 in multiple energy storage devices 10 or test results of a specific energy storage device 10. Alternatively, the energy storage device 10 can be charged with a constant current showing a second current value I2, and the slope A2 of the voltage change and the second current value I2 at this time can be substituted into the above formula (10) to calculate the electrostatic capacitance Cst of the energy storage unit 13.

[0353] Next, refer to Figure 16 The measurement method using the measuring apparatus 1B according to the fifth embodiment will be described. Figure 16 This is a flowchart illustrating an example of the state calculation processing (SB6) of the measuring device 1B.

[0354] The state operation processing (SB6) in this embodiment is replaced by the processing of steps SB631 to SB635. Figure 13 The process of step SB63 shown is described here. Only the processes of steps SB631 to SB635 will be described here. As the other processes are the same as those in the fourth embodiment, they will be omitted from the description.

[0355] In step SB62, controller 50B determines the... Figure 9 In step SB4, an approximate straight line Ln1B is set to represent the voltage change of the energy storage device 10 during constant current charging with a first current value I1, and the slope A1 of the approximate straight line Ln1B is obtained. Then, the controller 50B proceeds to step SB631.

[0356] In step SB631, the controller 50B switches the constant current supplied from the constant current source 20B to the energy storage device 10 from a first constant current to a second current value I2 that represents a current greater than the first current value I1.

[0357] The processing in steps SB632 and SB633 is the same as that in steps SB61 and SB62, respectively. Therefore, in steps SB632 and SB633, the controller 50B measures the voltage of the energy storage device 10 only at a specified time, calculates the approximate straight line Ln2 of the voltage change during the second constant current charging, and obtains the slope A2 of the approximate straight line Ln2.

[0358] In step SB634, the controller 50B calculates the discharge resistance Rpr of the energy storage device 10 based on the slopes A1 and A2 of an approximate straight line obtained according to the magnitude of the constant current indicating the first current value I1 and the second current value I2.

[0359] In this embodiment, the controller 50B substitutes the first current value I1, the slope A1 of the approximate straight line, the second current value I2, and the slope A2 of the approximate straight line into the above formula (12) to calculate the self-discharge current Ipr of the energy storage device 10. Then, the controller 50B divides the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr of the energy storage device 10 to calculate the discharge resistance Rpr of the energy storage device 10.

[0360] In step SB635, the controller 50B determines whether the energy storage device 10 is normal based on the calculated discharge resistance Rpr of the energy storage device 10.

[0361] In this embodiment, the controller 50B determines whether the calculated value of the discharge resistor Rpr is within a specified resistance range. If the calculated value of the discharge resistor Rpr is determined to be within the specified resistance range, the energy storage device 10 is in a normal state, and therefore the controller 50B proceeds to step SB64. On the other hand, if the calculated value of the discharge resistor Rpr is determined to be outside the specified resistance range, i.e., greater than the upper limit of the resistance range or less than the lower limit of the resistance range, the energy storage device 10 is in an abnormal state, and therefore the controller 50B proceeds to step SB65.

[0362] The condition of the energy storage device 10 is determined by performing the above state operation processing (SB6).

[0363] It should be noted that, in Figure 16 In the example shown, controller 50B switches the magnitude of the constant current supplied to energy storage device 10 only once and calculates the slope of the voltage change of energy storage device 10 twice, thereby calculating the self-discharge current Ipr. Alternatively, the magnitude of the constant current can be switched multiple times and the slope of the approximate straight line of voltage change can be calculated sequentially, thereby calculating multiple self-discharge currents Ipr, and the average or median value of these can be used as the final result.

[0364] Furthermore, in this embodiment, the controller 50B switches the magnitude of the constant current supplied from the constant current source 20B to the positive electrode 11 of the energy storage device 10 and calculates the self-discharge current Ipr, but it is not limited to this. For example, the connection relationship between the constant current source 20B and the energy storage device 10 can be reversed, and the constant current can be supplied from the constant current source 20B to the negative electrode 12 of the energy storage device 10 to discharge the energy storage device 10. In this state, the magnitude of the constant current is switched. In this case, the self-discharge current Ipr can also be calculated as in the above embodiment.

[0365] Furthermore, in this embodiment, the magnitude of the constant current supplied to the energy storage device 10 from the constant current source 20B is switched, but the self-discharge current Ipr and the discharge resistance Rpr can still be calculated even if the direction of the constant current is switched. Hereinafter, a method for calculating the self-discharge current Ipr of the energy storage device 10 when the direction of the constant current supplied to the energy storage device 10 is switched will be briefly explained.

[0366] The electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10 and the slope Ac of the voltage change when the energy storage device 10 is charged with a constant current showing the first current value I1, as shown in the following formula (13). Furthermore, the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10 and the slope Ad of the voltage change when the energy storage device 10 is discharged due to a constant current showing the second current value I2, as shown in the following formula (14).

[0367] [Formula 13]

[0368]

[0369] [Formula 14]

[0370]

[0371] If the self-discharge current Ipr is solved using the above formulas (13) and (14), the following formula (15) is derived.

[0372] [Formula 15]

[0373]

[0374] Therefore, by substituting the slope Ac of the voltage change during constant current charging (showing the first current value I1) and the slope Ad of the voltage change during constant current discharging (showing the second current value I2) into the above formula (15), the self-discharge current Ipr of the energy storage device 10 can be calculated. The discharge resistance Rpr is calculated by dividing the open-circuit voltage of the energy storage device 10 by the calculated self-discharge current Ipr.

[0375] In this case, regarding the first current value I1 and the second current value I2, at least one of their absolute values ​​can be set to one or several times the reference value of the self-discharge current Ipr. The absolute values ​​of both can be the same or different. For example, the first current value I1 can be set to 10 [μA], which is one times the reference value of the self-discharge current Ipr, and the second current value I2 can be set to the value obtained by multiplying the first current value I1 by "-1", i.e., -10 [μA]. Furthermore, regarding the slopes Ac and Ad of the voltage change, by... Figure 14 The same method is used to obtain the information.

[0376] Furthermore, in this embodiment, the controller 50B switches the magnitude of the constant current, but it is also possible to switch the direction of the constant current after switching the magnitude, or vice versa. In this case, multiple self-discharge currents Ipr can be obtained, and their average value can be used as the final result.

[0377] Furthermore, in this embodiment, the controller 50B calculates the self-discharge current Ipr of the energy storage device 10 by switching the constant current, but it is also possible to calculate the self-discharge current Ipr without switching the constant current. For example, if the electrostatic capacitance Cst of the energy storage unit 13 in formula (9) is known, the slope A1 of the approximate straight line of the voltage change of the energy storage device 10 can be obtained, and the slope A1, the first current value I1, and the known electrostatic capacitance Cst can be substituted into the above formula (9) to calculate the self-discharge current Ipr. Alternatively, the measured or predicted values ​​can be substituted into the electrostatic capacitance Cst of the energy storage unit 13 and the first current value I1 in the above formula (9) to generate an operation table representing the relationship between the slope A1 of the approximate straight line and the self-discharge current Ipr. Then, the generated operation table can be pre-recorded in the controller 50B. In this case, when the slope A1 of the approximate straight line is obtained, the controller 50B refers to the operation table and calculates the self-discharge current Ipr that is related to the slope A1 of the obtained approximate straight line.

[0378] Furthermore, as described above, the discharge resistance Rpr of the energy storage device 10 is calculated by dividing the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr. Therefore, if the open-circuit voltage (OCV) of the energy storage device 10 is known, a calculation table representing the relationship between the slope A1 of an approximate straight line and the discharge resistance Rpr can be generated and pre-stored in the controller 50B. In this case, when the slope A1 of the approximate straight line of voltage change of the energy storage device 10 is obtained, the controller 50B refers to the calculation table and calculates the discharge resistance Rpr that is related to the slope A1 of the obtained approximate straight line.

[0379] As described above, in this embodiment, the self-discharge current Ipr or discharge resistance Rpr is calculated based on one or more voltage changes of the energy storage device 10 detected within a short time, so the controller 50B can quickly estimate the internal state of the energy storage device 10.

[0380] Next, the effects of the fifth embodiment will be explained.

[0381] In this embodiment, the controller 50B of the measuring device 1B calculates the self-discharge current Ipr of the energy storage device 10 or the discharge resistance Rpr of the energy storage device 10 through which the self-discharge current Ipr flows based on the measured voltage change of the energy storage device 10.

[0382] Based on this configuration, the voltage change of the energy storage device 10 detected in a short time can be substituted into the above-mentioned formulas (9), (12), or (15) to calculate the self-discharge current Ipr or discharge resistance Rpr of the energy storage device 10. Therefore, the self-discharge current Ipr and discharge resistance Rpr can be measured as the internal state of the energy storage device 10 in a short time.

[0383] (Sixth Implementation Method)

[0384] Next, refer to Figure 17 The measuring device 2B of the sixth embodiment will be described. Figure 17 This is a diagram showing the configuration of measuring device 2B. Besides... Figure 8 In addition to the configuration shown, the measuring device 2B also includes a reference voltage source 30B.

[0385] The reference voltage source 30B generates a reference voltage relative to the voltage of the energy storage device 10, which serves as a reference. For example, when the voltage of the energy storage device 10 is approximately 3V, the reference voltage is set to be within the range of "-1V" to "+1V" relative to the voltage of the energy storage device 10. The reference voltage source 30B is, for example, constructed from a voltage generation circuit.

[0386] Voltage sensor 40B measures the potential difference between the voltage of the energy storage device 10 and the reference voltage. That is, voltage sensor 40B indirectly measures the voltage change of the energy storage device 10.

[0387] According to the sixth embodiment, by measuring the potential difference between the voltage of the energy storage device 10 and the reference voltage, a portion of the DC component of the voltage of the energy storage device 10 is removed, thereby improving the resolution of the voltage sensor 40B. This reduces the influence of internal noise in the voltage sensor 40B, thus shortening the measurement time.

[0388] It should be noted that the reference voltage source 30B can also be composed of other energy storage devices of the same type as the energy storage device 10. By measuring the potential difference between the energy storage device 10 and other energy storage devices under the same environment, the voltage fluctuation component accompanying the temperature change of the energy storage device 10 can be removed, thereby improving the detection accuracy of voltage changes caused by different internal states of the energy storage device 10.

[0389] The fourth to sixth embodiments have been described above, but the above embodiments only illustrate a part of the application examples of the present invention, and are not intended to limit the scope of the technology of the present invention to the specific configuration of the above embodiments.

[0390] For example, the degree of voltage change in the energy storage device 10 varies depending on the internal temperature of the energy storage device 10. This property is used to pre-store a temperature gauge representing the relationship between the voltage change and the internal temperature of the energy storage device 10 in the controller 50B. Then, the controller 50B can also estimate the internal temperature of the energy storage device 10 based on the detected voltage change.

[0391] Furthermore, while the self-discharge current Ipr and discharge resistance Rpr are calculated using the voltage change of the energy storage device 10 in the above embodiment, the electrostatic capacitance Cst of the energy storage unit 13 can also be calculated. For example, the electrostatic capacitance Cst of the energy storage unit 13 can be calculated by substituting the slope A2 of the voltage change when the energy storage device 10 is charged with a constant current showing the second current value I2 and the second current value I2 into the above formula (10).

[0392] In addition, the controller 50B can also determine the internal state of the energy storage device 10 based on the calculated electrostatic capacitance Cst. For example, the controller 50B determines the condition of the energy storage device 10 by determining whether the calculated value of the electrostatic capacitance Cst is within the specified normal range.

[0393] Furthermore, while the above embodiment measures a single energy storage device 10, it can also measure an energy storage device in which multiple energy storage devices 10 are connected in series. Additionally, the measuring device 1B includes a display unit 60B, but the display unit 60B may be omitted.

[0394] (Seventh Implementation)

[0395] The following is for reference Figures 18 to 25 The measuring device (hereinafter referred to as "measuring device") 1C of the energy storage device 10 according to the seventh embodiment will be described.

[0396] First, refer to Figure 18 The configuration of the energy storage device 10 and the configuration of the measuring device 1C will be described. Figure 18 This is a diagram showing the configuration of the measuring device 1C.

[0397] The energy storage device 10 is, for example, a single energy storage unit of a lithium-ion secondary battery. The energy storage device 10 is not limited to a secondary battery (chemical battery); it can also be, for example, an electric double-layer capacitor. Furthermore, the energy storage device 10 can also be an energy storage module composed of multiple energy storage units connected in series.

[0398] 10 images of energy storage devices Figure 18 This is represented by an equivalent circuit model. According to the equivalent circuit model, the energy storage device 10 has: a positive electrode 11, a negative electrode 12, an energy storage section 13, an internal resistor 14, and a parallel resistor 15. The energy storage section 13, the internal resistor 14, and the parallel resistor 15 are elements of the equivalent circuit that respectively represent the internal state of the energy storage device 10.

[0399] The energy storage section 13 is the electrostatic capacitance component of the energy storage device 10. The energy storage section 13 is charged by accumulating charge when a voltage higher than the unit voltage of the energy storage device 10 is applied. In the energy storage section 13, double-layer reaction mainly occurs when the current flowing through it during charging is relatively small, and chemical reaction mainly occurs when the current flowing through it during charging is relatively large. Here, the electrostatic capacitance of the energy storage section 13 is denoted as Cst[F], and the current flowing through the energy storage section 13 is denoted as Ist[A].

[0400] The internal resistor 14 is a series resistor connected in series with the energy storage unit 13 between the positive electrode 11 and the negative electrode 12. Here, the resistance value of the internal resistor 14 is set as Rir [mΩ], and the current flowing through the internal resistor 14 is set as Iir [A].

[0401] The parallel resistor 15 is a discharge resistor connected in parallel with the energy storage unit 13. The current flowing through the parallel resistor 15 is the self-discharge current, also known as the leakage current. Here, the resistance value of the parallel resistor 15 is set as Rpr [kΩ], and the self-discharge current flowing through the parallel resistor 15 is set as Ipr [A].

[0402] The measuring device 1C is a device or system for measuring the state of the energy storage device 10, including a detection device for detecting the time change of the voltage of the energy storage device 10, i.e., voltage change. The measuring device 1C includes: a constant current source 20C as a supply unit, a voltage sensor 40C as a measuring unit, a controller 50C as an acquisition unit and a calculation unit, and a display unit 60C.

[0403] The constant current source 20C is a DC power supply that charges the energy storage device 10 by supplying a constant current to the positive electrode 11 of the energy storage device 10 for detecting the internal state of the energy storage device 10. The constant current source 20C maintains the current supplied to the energy storage device 10 at a specified level. The constant current source 20C charges the energy storage device 10 by supplying a constant current at a level that is below the overvoltage and where the double-layer reaction mainly occurs.

[0404] In this embodiment, the constant current supplied from the constant current source 20C is set to one or several times the reference value of the self-discharge current Ipr of the energy storage device 10. The reference value of the self-discharge current Ipr is known information, for example, it is predetermined using statistical data summarizing the self-discharge currents Ipr of multiple energy storage devices 10 or test results of a specific energy storage device 10 with normal electrical characteristics. For example, the constant current supplied from the constant current source 20C is set to 10 [μA]. In this way, the constant current is determined based on the value of the self-discharge current Ipr of the energy storage device 10.

[0405] Here, when charging the energy storage device 10 by applying a constant voltage, it is difficult to stably apply a constant voltage to the energy storage device 10 at a level smaller than an overvoltage, where the double-layer reaction mainly occurs. In contrast, it is easy to supply a relatively small current on the order of microamps (μA) using a constant current source 20C. Therefore, in the measuring device 1C, a constant current at a level smaller than an overvoltage, where the double-layer reaction mainly occurs, can be stably supplied to the energy storage device 10 by using a constant current source 20C.

[0406] Voltage sensor 40C is a DC voltmeter that measures the voltage of the energy storage device 10. Voltage sensor 40C outputs an electrical signal showing the measured voltage in a timing sequence to controller 50C. In this embodiment, voltage sensor 40C measures the voltage of energy storage device 10 at least twice, including in a state where a constant current is supplied from constant current source 20C.

[0407] The controller 50C is a microcomputer equipped with a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface). The controller 50C can also be composed of multiple microcomputers. The controller 50C is a control device that controls various actions of the measuring device 1C by reading the program stored in the ROM from the CPU.

[0408] The controller 50C performs state measurement processing, controlling the constant current source 20C and the voltage sensor 40C to measure the internal state of the energy storage device 10. Specifically, the controller 50C controls the current supply from the constant current source 20C to the energy storage device 10, and calculates the internal state of the energy storage device 10 based on the electrical signal representing the voltage measured by the voltage sensor 40C.

[0409] For example, when the controller 50C is supplying a constant current to the energy storage device 10 from the constant current source 20C, it acquires an electrical signal from the voltage sensor 40C and detects the time change of the voltage of the energy storage device 10 indicated by the electrical signal. The controller 50C infers the self-discharge state of the energy storage device 10 based on the detected voltage change of the energy storage device 10.

[0410] The display unit 60C displays information such as the determination or calculation results of the controller 50C to notify the user. The display unit 60C is, for example, a touch screen, configured so that the user can visually confirm the information and operate it.

[0411] The operation unit 70C generates operation signals for operating the controller 50C. The operation unit 70C is, for example, an input device consisting of a keyboard and a mouse. The operation unit 70C outputs operation signals to the controller 50C, for example, indicating the execution of state measurement processing, based on user input operations.

[0412] Next, refer to Figure 19 The configuration of the controller 50C of the measuring device 1C in this embodiment will be described. Figure 19 This is a block diagram representing the functional structure of controller 50C.

[0413] The controller 50C includes: an operation receiving unit 51, a measurement command unit 52, a voltage acquisition unit 53, a storage unit 54, and an arithmetic unit 55.

[0414] Operation receiving unit 51 accepted the pass Figure 18 The operation signal generated by the operation unit 70C is shown. When the operation receiving unit 51 receives an operation signal instructing the execution of the status measurement process of the energy storage device 10, it instructs the measurement command unit 52 to execute the status measurement process.

[0415] When the operation receiving unit 51 receives the above instruction, the measurement command unit 52 sends a control signal indicating the current value for detecting the self-discharge current Ipr of the energy storage device 10 to the constant current source 20C. Furthermore, the measurement command unit 52 sends a control signal instructing the energy storage device 10 to measure its voltage to the voltage sensor 40C.

[0416] The voltage acquisition unit 53 receives an electrical signal representing the voltage of the energy storage device 10 from the voltage sensor 40C. The voltage acquisition unit 53 records the received electrical signal as measurement data in the storage unit 54.

[0417] The storage unit 54 is composed of ROM and RAM, forming a computer-readable recording medium that stores a program for executing the state measurement process of the energy storage device 10. The storage unit 54 stores information required for executing the state measurement process of the energy storage device 10.

[0418] In this embodiment, the storage unit 54 includes a constant current storage unit 541, a change information storage unit 542, and a voltage measurement storage unit 543.

[0419] The constant current storage unit 541 stores the current value of the constant current supplied to the energy storage device 10 from the constant current source 20C. The current value stored in the constant current storage unit 541 can be predetermined or recorded from the operation receiving unit 51 via user input. In this embodiment, the constant current value is set as a reference value of the self-discharge current Ipr of the energy storage device 10, for example, set to 10 [μA].

[0420] The change information storage unit 542 stores change information for the change of the open-circuit voltage of a specific energy storage device 10. The open-circuit voltage of the energy storage device 10 referred to here means the voltage of the energy storage device 10 when the positive electrode 11 and negative electrode 12 are open-circuited. For example, even when the energy storage device 10 is connected to a constant current source 20C, the state of stopping the constant current supply from the constant current source 20C to the energy storage device 10 is also included in the state of opening the positive electrode 11 and negative electrode 12 of the energy storage device 10.

[0421] The change information stored in the change information storage unit 542 may include, for example, measured data, statistical data, theoretical data obtained from theoretical formulas, or simulation results using equivalent circuits that represent the time-varying open-circuit voltage of the energy storage device 10. Alternatively, instead of the aforementioned data, approximate formulas that approximate the time-varying open-circuit voltage of the energy storage device 10, or the slope of an approximate straight line, may also be used as change information.

[0422] In this embodiment, before supplying a constant current to the energy storage device 10, an electrical signal showing the open-circuit voltage of the energy storage device 10 as measured by the voltage sensor 40C is stored as change information of the energy storage device 10 in the change information storage unit 542. In this case, before the constant current supply from the constant current source 20C begins, the voltage acquisition unit 53 acquires an electrical signal representing the open-circuit voltage of the energy storage device 10 from the voltage sensor 40C. Furthermore, the voltage acquisition unit 53 records the acquired electrical signal as change information of the energy storage device 10 in the change information storage unit 542.

[0423] The voltage measurement storage unit 543 stores measurement data of the measured voltage of the energy storage device 10, displayed in sequence. The measured voltage of the energy storage device 10 referred to here is the voltage of the energy storage device 10 measured by the voltage sensor 40C when a constant current is supplied to the energy storage device 10 from the constant current source 20C. When a constant current is supplied to the energy storage device 10, the voltage acquisition unit 53 records the electrical signal acquired from the voltage sensor 40C as measurement data in the voltage measurement storage unit 543.

[0424] The calculation unit 55 calculates the internal state of the energy storage device 10 based on the change in the measured voltage of the energy storage device 10 supplied with constant current. At this time, the calculation unit 55 corrects the change in the measured voltage of the energy storage device 10 based on the change information pre-stored in the storage unit 54.

[0425] In this embodiment, the arithmetic unit 55 includes a voltage change detection unit 551, a voltage change correction unit 552, and an internal state arithmetic unit 553.

[0426] The voltage change detection unit 551 constitutes a detection unit, which detects the change of the measured voltage of the energy storage device 10 based on the measured voltage of the energy storage device 10 measured by the voltage sensor 40C.

[0427] In this embodiment, the voltage change detection unit 551 reads the measurement data of the energy storage device 10 from the measurement voltage storage unit 543, and calculates the slope of the time change of the measurement voltage of the energy storage device 10, i.e., the time change rate of the measurement voltage, based on the read measurement data. For example, the voltage change detection unit 551 refers to the measurement voltage storage unit 543. Then, the voltage change detection unit 551 calculates the slope of the voltage change of the energy storage device 10 under the constant current supply state based on the initial voltage when the constant current is supplied and the charging voltage under the constant current supply state from the constant current source 20C.

[0428] The voltage change detection unit 551 outputs the slope of the calculated voltage change as the detection result to the voltage change correction unit 552. Instead of the slope of the voltage change, the voltage change detection unit 551 can also calculate the amount of change in the measured voltage from the start of constant current supply until a predetermined measurement time has elapsed as the detection result.

[0429] The voltage change correction unit 552 constitutes a correction unit, which corrects the change in the measured voltage of the energy storage device 10 based on the change information of the energy storage device 10 stored in the change information storage unit 542.

[0430] In this embodiment, the voltage change correction unit 552 reads the change information of the energy storage device 10 from the change information storage unit 542, and identifies the change in the open-circuit voltage of the energy storage device 10 based on the read change information. The voltage change correction unit 552 subtracts the identified change in open-circuit voltage from the change in the measured voltage of the energy storage device 10 detected by the voltage change detection unit 551 to correct the change in the measured voltage of the energy storage device 10.

[0431] Specifically, the voltage change correction unit 552 calculates the slope of the voltage change of the open-circuit voltage of the energy storage device 10 based on the time-sequential display of the change information of the open-circuit voltage of the energy storage device 10 measured by the voltage sensor 40C. Next, when the slope of the time change of the measured voltage of the energy storage device 10 is obtained from the voltage change detection unit 551, the voltage change correction unit 552 subtracts the obtained slope of the time change from the calculated slope of the voltage change. Then, the voltage change correction unit 552 outputs the value obtained after subtraction as the corrected change of the measured voltage to the internal state calculation unit 553.

[0432] Instead, the voltage change correction unit 552 can also calculate the change in open-circuit voltage of the energy storage device 10 per unit measurement time based on the change information. Then, the voltage change correction unit 552 can also use the value obtained by subtracting the calculated change from the change in measurement voltage of the energy storage device 10 per unit measurement time as the corrected change in measurement voltage.

[0433] In this way, the voltage change correction unit 552 constitutes a subtraction correction unit, which corrects the change in the measured voltage of the energy storage device 10 by subtracting the change in the open circuit voltage specified by the change information of the energy storage device 10 from the change in the measured voltage detected by the voltage change detection unit 551.

[0434] The internal state calculation unit 553 constitutes a calculation unit, which calculates the internal state of the energy storage device 10 based on the change of the measured voltage corrected by the voltage change correction unit 552.

[0435] For example, the internal state calculation unit 553 determines the condition of the internal state of the energy storage device 10 based on the change in the measured voltage of the calibrated energy storage device 10. Alternatively, the internal state calculation unit 553 can also calculate the current flowing through the energy storage device 10 based on the change in the measured voltage of the calibrated energy storage device 10. Figure 18 The self-discharge current of the parallel resistor 15, the resistance value of the parallel resistor 15, or the electrostatic capacitance of the energy storage section 13 are shown.

[0436] In this embodiment, if the change in the corrected measured voltage is within the normal range, the internal state calculation unit 553 determines that the energy storage device 10 is normal; if the change in the corrected measured voltage is outside the normal range, the internal state calculation unit 553 determines that the energy storage device 10 is abnormal. In this way, the internal state calculation unit 553 determines whether the energy storage device 10 is functioning properly.

[0437] Specifically, when the slope of the corrected measured voltage is obtained from the voltage change correction unit 552, the internal state calculation unit 553 determines whether the energy storage device 10 is functioning properly based on the obtained slope of the measured voltage. The internal state calculation unit 553 outputs the determination result, indicating whether the energy storage device 10 is in an abnormal or normal state, to the display unit 60C.

[0438] Next, refer to Figure 20 The operation of the measuring device 1C in this embodiment will be explained.

[0439] Figure 20 This is a flowchart illustrating an example of a measurement method for measuring the state of a storage device 10 using a measuring device 1C. In this example, the measuring device 1C performs the measurement, for example, in an environment where the storage device 10 is housed in a constant-temperature bath where the ambient temperature is maintained at a constant level, thereby suppressing temperature changes in the storage device 10.

[0440] First, when performing the above measurement, the measuring device 1C is connected to the energy storage device 10, and is configured to be able to measure the voltage state of the energy storage device 10 by the voltage sensor 40C, and to be able to supply constant current to the energy storage device 10 from the constant current source 20C.

[0441] In step SC1, the controller 50C acquires change information regarding the variation of the open-circuit voltage for a specific energy storage device 10.

[0442] In this example, before supplying a constant current source 20C to the energy storage device 10, the controller 50C causes the voltage sensor 40C to measure the voltage of the energy storage device 10. Then, the controller 50C obtains an electrical signal representing the open-circuit voltage of the energy storage device 10 from the voltage sensor 40C as change information, and then proceeds to step SC2.

[0443] In step SC2, the controller 50C supplies a constant current to the energy storage device 10 from the constant current source 20C to begin charging the energy storage device 10.

[0444] In step SC3, the controller 50C causes the voltage sensor 40C to measure the voltage of the energy storage device 10 under constant current conditions supplied by the constant current source 20C. Thus, an electrical signal representing the measured voltage of the energy storage device 10 is input from the voltage sensor 40C to the controller 50C.

[0445] In step SC4, the controller 50C performs a state calculation process to calculate the internal state of the energy storage device 10 based on the measured voltage of the energy storage device 10 as indicated by the electrical signal. For this state calculation process, refer to... Figure 23 As described later.

[0446] When step SC4 is completed, the series of processes for the measurement method using measuring device 1C ends.

[0447] Here, refer to Figure 21 and Figure 22 A specific example of the processing in step SC1 will be provided. Figure 21 This is a diagram illustrating the change in open-circuit voltage of the energy storage device 10 after a discharge test. Figure 22 It means from Figure 21 The graph shows the variation of the open-circuit voltage of the energy storage device 10 starting from point P.

[0448] Figure 21 The discharge test shown is a test example of a normal discharge in which a chemical reaction mainly occurs in the energy storage device 10. In this discharge test, a discharge current Id of approximately 10 mA for about 120 s is supplied to the negative electrode 12 of the energy storage device 10 to reduce the charging capacity of the energy storage device 10. Here, the current flowing from the positive electrode 11 of the energy storage device 10 to the negative electrode 12 is defined as positive (+), and the current flowing from the negative electrode 12 of the energy storage device 10 to the positive electrode 11 is defined as negative (-).

[0449] The discharge current Id is approximately 1,000 times larger than the constant current supplied from the constant current source 20C in this embodiment. Therefore, charging the energy storage device 10 by supplying a constant current from the constant current source 20C can also be referred to as "micro-charging".

[0450] like Figure 21 As shown, immediately after the discharge test, the open-circuit voltage of the energy storage device 10 rises sharply, then rises slowly until it reaches point P (marked with a circular symbol). After reaching point P, the open-circuit voltage of the energy storage device 10 continues to fluctuate for several hours or more. The same occurs after the charging test.

[0451] For example, in order to perform the state measurement process of this embodiment, when a constant current is supplied from the constant current source 20C at point P, such as Figure 22 As shown, the rise in open-circuit voltage of the energy storage device 10 is approximately 150 [μV] over 600 seconds.

[0452] In contrast, the change in the measured voltage of the energy storage device 10 when the constant current source 20C supplies a constant current to the energy storage device 10 is, for example, around tens of μV over 600 [s]. Therefore, the inventors discovered that the variation in the open-circuit voltage of the energy storage device 10 after charging and discharging has a significant impact on the measurement accuracy of the measuring device 1C.

[0453] Therefore, when performing the state measurement process of this embodiment after conducting the charge and discharge test of the energy storage device 10, in order to ensure the measurement accuracy, it is necessary to wait for several hours or more before performing the state measurement process, making it difficult to perform the measurement quickly.

[0454] As a countermeasure, in this embodiment, in order to correct for changes in the measured voltage of the energy storage device 10, Figure 20 In step SC1 shown, controller 50C acquires change information related to the change in the open-circuit voltage of energy storage device 10.

[0455] Figure 22 The data shown by the dashed line M0 is an example of the change information obtained through the processing in step SC1. The data by the dashed line M0 represents the measurement data of the open-circuit voltage of the energy storage device 10 as measured by the preceding voltage sensor 40C, which supplies a constant current to the energy storage device 10 from the constant current source 20C.

[0456] In this way, during the processing of step SC1, the controller 50C acquires the electrical signal output from the voltage sensor 40C as change information before starting to supply a constant current to the energy storage device 10. The electrical signal from the voltage sensor 40C is used as an example for this change information, but simulation results or theoretical formulas can also be used.

[0457] Next, refer to Figures 23 to 25 , for Figure 20 The state operation processing performed in step SC4 is explained below.

[0458] Figure 23 This is a flowchart illustrating an example of the state calculation processing (SC4) of the measuring device 1C. Figure 24 This is a graph illustrating the change in the measured voltage relative to the charging time of the energy storage device 10 in this embodiment. Figure 25 This is a graph illustrating, for example, the change in the measured voltage after correction relative to the charging time of the energy storage device 10 in this embodiment.

[0459] exist Figure 23 In the example shown, as a state operation process (SC4), the controller 50C determines whether the energy storage device 10 is good or bad based on the voltage change of the energy storage device 10.

[0460] In step SC41, the controller 50C determines whether the charging time, which is the elapsed time since the constant current supply to the energy storage device 10 begins, exceeds a predetermined time. The predetermined time is preset to be the length of time during which the voltage change of the energy storage device 10 differs between normal and abnormal conditions.

[0461] In step SC41, if it is determined that the charging time has not exceeded the predetermined time, the controller 50C continues to supply a constant current to the energy storage device 10 until it is determined that the charging time has exceeded the predetermined time. On the other hand, if it is determined that the charging time has exceeded the predetermined time, the controller 50C moves to step SC42.

[0462] In step SC42, the controller 50C detects changes in the measured voltage of the energy storage device 10 based on the measured voltage of the energy storage device 10 measured by the voltage sensor 40C.

[0463] As a specific example, the controller 50C calculates an approximate straight line approximating the time change of the measured voltage of the energy storage device 10 based on the initial voltage at the start of charging and the charging voltage under constant current conditions supplied from the constant current source 20C. More specifically, the controller 50C calculates an approximate straight line of the measured voltage of the energy storage device 10 using the least squares method based on the minute charging voltage measured in each control cycle.

[0464] Alternatively, the controller 50C can also be configured to detect changes in the measured voltage of the energy storage device 10 based on the difference between the initial voltage at the start of charging and the charging voltage under constant current conditions supplied from the constant current source 20C. In this case, it is sufficient to measure the voltage of the energy storage device 10 twice using the voltage sensor 40C, and therefore, a multiplexer can be used, for example, for switching to perform the voltage measurement. This simplifies the measuring device 1C.

[0465] In step SC43, the controller 50C corrects the approximate straight line based on the variation information obtained in step SC1. That is, the controller 50C corrects the detected changes in the measured voltage of the energy storage device 10 based on the variation information.

[0466] As a specific example, firstly, the controller 50C calculates an approximate straight line that approximates the change in the open-circuit voltage of the energy storage device 10 based on the change information of the energy storage device 10, and obtains the slope of this approximate straight line. Next, the controller 50C calculates the slope of the approximate straight line of the obtained open-circuit voltage by subtracting the slope of the approximate straight line of the measured voltage obtained in step SC3, and uses the resulting value as the slope of the corrected approximate straight line of the measured voltage.

[0467] In step SC44, the controller 50C determines whether the slope of the corrected approximate straight line is within a specified range. If the slope of the corrected approximate straight line is determined to be within the specified range between the upper and lower limits, the energy storage device 10 is in a normal state, and therefore proceeds to step SC45. On the other hand, if in step SC44 the slope of the corrected approximate straight line is determined to be outside the specified range, i.e., greater than the upper limit of the specified range or less than the lower limit of the specified range, the energy storage device 10 is in an abnormal state, and therefore proceeds to step SC46.

[0468] In step SC45, assuming the energy storage device 10 is in a normal state, the controller 50C displays its message on the display unit 60C to notify the user. On the other hand, in step SC46, assuming the energy storage device 10 is in an abnormal state, the controller 50C displays its message on the display unit 60C to notify the user.

[0469] The condition of the energy storage device 10 is determined by performing the above state operation processing (SC4).

[0470] Next, refer to Figure 24 and Figure 25 Specific examples of the processing in steps SC42 to SC44 are explained. Figure 24 and Figure 25 The horizontal axis represents the charging time [s], which is the elapsed time from the start of supplying constant current to the energy storage device 10, and the vertical axis represents the difference [μV] between the initial voltage and the charging voltage measured by the voltage sensor 40C.

[0471] Figure 24 The data represented by the dashed line M0 is... Figure 22 The measured data shown represents the rise in the open-circuit voltage of the energy storage device 10, that is, the variation in the open-circuit voltage of the energy storage device 10. The solid line is an approximate straight line Lm0, which is the approximate straight line of the open-circuit voltage obtained through the processing in step SC43.

[0472] On the other hand, the data of the dashed line M1 represents the amount of rise in the measured voltage of the energy storage device 10 when it is charged from the constant current source 20C with a constant current value I1 of +10 [μA] when the energy storage device 10 is in a normal state. The solid line is an approximate straight line Lm1 of the measured voltage obtained through the processing in step SC42.

[0473] Figure 24The data shown by solid line C1 is the change in the measured voltage corrected by the processing in step SC43. It is the difference data obtained by taking the difference between the data of the corresponding dashed line M1 and the data of dashed line M0. The data of solid line C1 removes the variation component of the open circuit voltage of the energy storage device 10, that is, the voltage change component of the measured voltage caused by the constant current supplied to the energy storage device 10.

[0474] Then, the solid line approximates the straight line Ln1C, which is a straight line with a corrected slope Rn obtained by subtracting the slope of the approximate straight line Lm0 from the slope of the approximate straight line Lm1, and is an approximate straight line of the change in the measured voltage after correction.

[0475] Reference Figure 24 The voltage variation component in the approximate straight line Lm1 caused by the charging and discharging of the energy storage device 10 is greater than the voltage variation component caused by the constant current supply to the energy storage device 10. Therefore, the controller 50C subtracts the slope of the approximate straight line Lm0 obtained by approximating the open-circuit voltage before the constant current supply begins from the slope of the approximate straight line Lm1 obtained by approximating the measured voltage at the time of constant current supply. Thus, the voltage variation component caused by the constant current supply to the energy storage device 10 can be extracted. In this way, the controller 50C corrects for changes in the measured voltage of the energy storage device 10 when a constant current is supplied.

[0476] exist Figure 25 In the text, the change in the calibrated measurement voltage is magnified, and the change in voltage is omitted. Figure 24 The dashed lines M1 and M0, and the approximate straight lines Lm1 and Lm0 are shown. Here, only the scale ratio of the vertical axis is considered. Figure 24 The scale of the vertical axis shown is enlarged.

[0477] Figure 25 The dashed lines shown represent examples of voltage changes when the energy storage device 10 is in an abnormal state. The straight lines of the dashed lines are approximate straight lines La1C, which are obtained through the processing in step SC42. Furthermore, the slope of the approximate straight line Ln1C is set as Rn, and the slope of the approximate straight line La1C is set as Ra.

[0478] also, Figure 25 The two double-dotted lines shown represent the upper limit Rmax and lower limit Rmin of the slope of the approximate straight line, respectively. The slope between the two double-dotted lines represents the slope of the energy storage device 10 under normal conditions. It should be noted that the upper limit Rmax and lower limit Rmin of the slope of the approximate straight line are set to, for example, ±10% of the approximate straight line obtained by prior measurement using the energy storage device 10 under normal conditions.

[0479] Reference Figure 25The approximate straight line Ln1C (slope Rn), represented by a solid line, lies between the upper limit Rmax and the lower limit Rmin of the slope of the approximate straight line. Therefore, the controller 50C determines that the energy storage device 10 is in a normal state. On the other hand, the approximate straight line La1C (slope Ra), represented by a dashed line, does not lie between the upper limit Rmax and the lower limit Rmin of the slope of the approximate straight line. Therefore, the controller 50C determines that the energy storage device 10 is in an abnormal state.

[0480] In this way, the controller 50C determines whether the energy storage device 10 is in a normal state or an abnormal state based on whether the slope of the approximate straight line is between the upper limit value Rmax and the lower limit value Rmin.

[0481] It should be noted that, in Figure 25 In the example shown, the determination of the quality of the energy storage device 10 takes 600 seconds (TC1), but the difference in slope between the approximate straight line Ln1C (represented by the solid line) and the approximate straight line La1C (represented by the dashed line) can be clearly confirmed in about 100 seconds. In this way, the determination of the quality of the energy storage device 10 can be performed in a short time of about a few minutes in the measuring device 1C.

[0482] As described above, the measuring device 1C of this embodiment charges the energy storage device 10 with a small constant current from the constant current source 20C, measures the charging voltage under constant current conditions, and thus detects the change in the measured voltage of the energy storage device 10. The measuring device 1C then determines whether the detected change in the measured voltage of the energy storage device 10 is within the normal range. If the change in the measured voltage is within the normal range, the energy storage device 10 is determined to be normal. Therefore, there is no need to wait for the voltage of the energy storage device 10 to decrease due to self-discharge, thus the time spent determining the condition of the energy storage device 10 is short.

[0483] At this time, the constant current source 20C supplies a constant current, which is less than the overvoltage and mainly causes double-layer reaction, to charge the energy storage device 10. Since the constant current supplied to the energy storage device 10 is relatively small, the ratio of the current Ist [A] flowing through the energy storage section 13 to the current Ipr [A] flowing through the parallel resistor 15 is large. Therefore, the difference in the slope of the charging curve caused by the presence or absence of the parallel resistor 15 becomes larger, making it easier to determine whether the energy storage device 10 is functioning properly.

[0484] In addition, the measuring device 1C corrects for changes in the measured voltage of the energy storage device 10 based on variation information of the open-circuit voltage variation for a specific energy storage device 10. Therefore, the variation component in the measured voltage of the energy storage device 10, excluding the voltage variation component caused by the constant current supply, is reduced. Thus, even when the open-circuit voltage variation of the energy storage device 10 is large, there is no need to wait for the variation to end, and the quality of the energy storage device 10 can be quickly determined.

[0485] Therefore, the quality of the energy storage device 10 can be determined in a short time.

[0486] It should be noted that in the above embodiment, the voltage sensor 40C measures the voltage of the energy storage device 10 as the initial voltage after the constant current supply begins. However, it is also possible to measure the voltage of the energy storage device 10 as the initial voltage before the constant current supply begins. In this case, the voltage of the energy storage device 10 can be measured more than twice, including the state when the constant current is supplied, so an approximate linear change in the voltage of the energy storage device 10 can be obtained.

[0487] Next, the effects of the seventh embodiment will be explained.

[0488] The measuring device 1C in this embodiment constitutes a device for detecting voltage changes in the energy storage device 10. The measuring device 1C includes: a constant current source 20C (supply unit) that supplies a constant current to the energy storage device 10; and a voltage sensor 40C (measuring unit) that measures the voltage associated with the energy storage device 10 to which a constant current is supplied. The measuring device 1C also includes a controller 50C (processing unit) that detects the measured voltage changes in the energy storage device 10. Then, the measuring device 1C acquires the voltage changes of the energy storage device 10 based on electrical characteristics that serve as a reference for the energy storage device 10.

[0489] Furthermore, regarding the method for detecting voltage changes in the energy storage device 10 in this embodiment, a constant current is supplied to the energy storage device 10, and the voltage associated with the energy storage device 10 to which the constant current is supplied is measured, and the measured voltage change of the energy storage device is detected. This method obtains the voltage change of the energy storage device 10, which varies according to the magnitude of the self-discharge current or discharge resistance of the energy storage device 10, based on the electrical characteristics that serve as a reference for the energy storage device 10.

[0490] The aforementioned reference electrical characteristics of the energy storage device 10 refer to the electrical characteristics of the energy storage device 10 in the open-circuit state in this embodiment, specifically the variation in the open-circuit voltage of the energy storage device 10. The measuring device 1C in this embodiment corrects for the detected voltage change of the energy storage device 10 supplied with a constant current based on the variation in the open-circuit voltage of the energy storage device 10, thereby obtaining the corrected voltage change of the energy storage device 10. Specifically, as described below.

[0491] The measuring device 1C in this embodiment, which includes a detection apparatus for detecting voltage changes in the energy storage device 10, includes a voltage acquisition unit 53 of a controller 50C that acquires change information regarding the change in the open-circuit voltage of a specific energy storage device 10. Furthermore, the measuring device 1C includes a constant current source 20C that supplies a constant current to the energy storage device 10, and a voltage sensor 40C that measures the voltage of the energy storage device 10 supplied with a constant current. The measuring device 1C also includes a calculation unit 55 of the controller 50C that detects voltage changes in the energy storage device 10 based on the measured voltage of the energy storage device 10. Then, the calculation unit 55 corrects the detected voltage changes in the energy storage device 10 based on the change information.

[0492] Then, the measuring device 1C for measuring the state of the energy storage device 10 in this embodiment includes the constant current source 20C, voltage sensor 40C, and voltage acquisition unit 53. In addition, the measuring device 1C includes a calculation unit 55 that calculates the internal state of the energy storage device 10 based on the change in the measured voltage, which is the measured voltage of the energy storage device 10. Then, the calculation unit 55 corrects the change in the measured voltage of the energy storage device 10 based on the change information.

[0493] Furthermore, the method for measuring the state of the energy storage device 10 in this embodiment includes an acquisition step (SC1) for acquiring change information regarding the change in the open-circuit voltage of a specific energy storage device 10. In addition, the method includes a supply step (SC2) for supplying a constant current to the energy storage device 10; and a measurement step (SC3) for measuring the voltage of the energy storage device 10 supplied with the constant current. Moreover, the method includes a calculation step (SC4) for calculating the internal state of the energy storage device 10 based on the measured change in the measured voltage of the energy storage device 10. Then, the calculation step (SC4) corrects for the change in the measured voltage of the energy storage device 10 based on the change information.

[0494] First, the different internal states of the energy storage device 10 are easily manifested in the different time changes of the voltage of the energy storage device 10. Therefore, according to the above configuration, a constant current is supplied to the energy storage device 10, which increases the voltage change of the energy storage device 10. Therefore, the time required to determine the voltage change and internal state of the energy storage device 10 can be shortened.

[0495] In addition, according to the above configuration, the change in the measured voltage of the energy storage device 10 supplied with constant current is corrected based on the change information of the energy storage device 10, thereby reducing the variation components other than the voltage change components caused by the constant current supply.

[0496] For example, such as Figure 21 As shown, after the energy storage device 10 is charged and discharged, it takes time for the open-circuit voltage of the energy storage device 10 to stabilize. Figure 24As shown, for a period of several hundred seconds after charging and discharging, the variation component (Lm0) accompanying the normal charging and discharging is much larger than the voltage variation component (Ln1C) caused by the constant current supply to the energy storage device 10.

[0497] In this situation, as described in the above embodiment, the change in the measured voltage of the energy storage device 10 is corrected based on the change information of the energy storage device 10, thereby largely eliminating the voltage fluctuation component accompanying charging and discharging. Therefore, the state of the energy storage device 10 can be measured with high accuracy. As a result, the measurement of the energy storage device 10 can be started quickly without waiting for the open-circuit voltage of the energy storage device 10 to stabilize.

[0498] Furthermore, the inventors discovered that even a change of only about 1.0 °C in the ambient temperature of the room housing the energy storage device 10 could affect the measurement accuracy of the measuring device 1C. Figure 25 In the example shown, the voltage change component (Ln1C) caused by the constant current supply is about 5 μV over 100 s, which is the same as the change in open-circuit voltage of the energy storage device 10 when the ambient temperature changes by about 0.5 °C over 100 s.

[0499] Therefore, in environments where the ambient temperature of the energy storage device 10 gradually rises or falls, information about its fluctuations is acquired in advance, and the changes in the measured voltage are corrected based on this information. This reduces the voltage fluctuation component in the measured voltage that is accompanied by temperature changes. As a result, the state of the energy storage device 10 can be determined with high accuracy even without waiting for the ambient temperature of the energy storage device 10 to stabilize.

[0500] In this way, by using the variation information of the energy storage device 10, variations in the open-circuit voltage of the energy storage device 10 after charging and discharging, or variations in the open-circuit voltage caused by changes in ambient temperature, are suppressed. Therefore, it is not necessary to wait for the measurement to converge until the environmental variation components caused by the voltage of the energy storage device 10 converge.

[0501] As described above, based on the above configuration, a constant current can be supplied to the energy storage device 10, thereby increasing the variation of the measured voltage of the energy storage device 10 and reducing the environmentally-induced variation component in the measured voltage. Therefore, the state of the energy storage device 10 can be determined in a short time.

[0502] Furthermore, in this embodiment, the voltage sensor 40C measures the open-circuit voltage of the energy storage device 10 and outputs a signal representing the measured open-circuit voltage as change information of the energy storage device 10 to the controller 50C. Subsequently, the voltage sensor 40C measures the voltage supplied to the energy storage device 10 with a constant current.

[0503] Based on this configuration, the actual fluctuation of the open-circuit voltage of the specific energy storage device 10 can be observed, thus accurately extracting the change component of the measured voltage caused by the constant current supply to the energy storage device 10. Furthermore, the voltage fluctuation of the energy storage device 10 after the constant current supply ends tends to become unstable with the constant current supply. Therefore, by using the voltage fluctuation of the energy storage device 10 before the constant current supply begins as fluctuation information, the change component of the measured voltage accompanying the constant current supply to the energy storage device 10 can be eliminated. Thus, the change in the measured voltage of the energy storage device 10 under constant current supply conditions can be accurately corrected.

[0504] Furthermore, the calculation unit 55 in this embodiment includes a voltage change detection unit 551, which detects changes in the measured voltage of the energy storage device 10 based on the measured voltage of the energy storage device 10. Additionally, the calculation unit 55 includes a voltage change correction unit 552, which corrects the change in the measured voltage by subtracting the change in the open-circuit voltage specified by the change information from the detected change in the measured voltage.

[0505] According to this configuration, the change information of the energy storage device 10 is used to correct the change of the measured voltage through simple calculation processing, thereby reducing the processing burden of the calculation unit 55.

[0506] Furthermore, in this embodiment, the constant current source 20C supplies a constant current to the energy storage device 10 that is less than the overvoltage and where the double-layer reaction mainly occurs.

[0507] According to this configuration, the magnitude of the constant current supplied to the energy storage device 10 is small, so the ratio of the current Ist[A] flowing through the energy storage section 13 to the current Ipr[A] flowing through the parallel resistor 15 becomes larger. Therefore, the difference in the slope of the charging curve caused by the presence or absence of the parallel resistor 15 becomes larger, making it easier to determine the state of the energy storage device 10.

[0508] (Eighth Implementation Method)

[0509] Next, the controller 50C of the measuring apparatus 1C in the eighth embodiment will be described. The basic structure of the measuring apparatus 1C in this embodiment is similar to... Figure 18 and Figure 19 The configuration shown is the same; descriptions that are repeated in the seventh embodiment are omitted. Hereinafter, Figure 18 The resistance value of the parallel resistor 15 of the energy storage device 10 shown is called the discharge resistor Rpr, and the current flowing through the parallel resistor 15 is called the self-discharge current Ipr. Moreover, at least one of the self-discharge current Ipr and the discharge resistor Rpr is also referred to as a "parameter related to self-discharge".

[0510] In this embodiment, the controller 50C calculates parameters related to self-discharge as the internal state of the energy storage device 10 based on the measured voltage of the energy storage device 10 measured by the voltage sensor 40C when a constant current is supplied to the energy storage device 10. This differs from the seventh embodiment described above.

[0511] Specifically, the constant current source 20C sequentially supplies different constant current values ​​to the energy storage device 10, and the voltage sensor 40C measures the voltage of the energy storage device 10 according to each constant current supplied to it. Then, the controller 50C calculates the discharge resistance Rpr and the self-discharge current Ipr according to each constant current based on the change in the measured voltage of the energy storage device 10 measured by the voltage sensor 40C.

[0512] The measurement instruction unit 52 of the controller 50C constitutes a switching unit, which switches the constant current supplied to the energy storage device 10.

[0513] In this embodiment, the measurement command unit 52 switches the constant current supplied to the energy storage device 10 from the constant current source 20C between a constant current displaying a first current value and a constant current displaying a second current value. The first and second current values ​​are stored in the constant current storage unit 541. Hereinafter, the constant current displaying the first current value will also be referred to as the "first constant current", and the constant current displaying the second current value will also be referred to as the "second constant current".

[0514] The first current value is set similarly to that in the seventh embodiment, to be one or several times the reference value of the self-discharge current Ipr of the energy storage device 10. In this embodiment, it is set to 10 [μA] times the reference value of the self-discharge current Ipr. Furthermore, the second current value is set to several tens of times or more the reference value of the self-discharge current Ipr of the energy storage device 10. In this embodiment, it is set to fifty times the reference value of the self-discharge current Ipr. Thus, both the first and second current values ​​are predetermined based on the value of the self-discharge current Ipr.

[0515] The reference value of the self-discharge current Ipr is known information, such as statistical data summarizing the self-discharge currents Ipr of multiple energy storage devices 10 or test results of the self-discharge current Ipr of a specific energy storage device 10 with normal electrical characteristics, and can be determined in advance.

[0516] The voltage change detection unit 551 of the controller 50C constitutes a detection unit, which detects the change of the measured voltage of the energy storage device 10 based on the magnitude of the constant current supplied from the constant current source 20C.

[0517] In this embodiment, the voltage change detection unit 551 calculates the slope of the time change of the measured voltage of the energy storage device 10 based on the initial voltage when the constant current is supplied and the charging voltage under the condition that the constant current is supplied from the constant current source 20C, according to the magnitude of each constant current. Instead, as... Figure 24 As shown, for each constant current, the voltage change detection unit 551 can also calculate an approximate straight line Lm1 that approximates the time change of the measured voltage of the energy storage device 10, and use the slope of this approximate straight line Lm1 as the slope of the measured voltage.

[0518] The voltage change correction unit 552 of the controller 50C constitutes a correction unit, which corrects the change in the measured voltage of the energy storage device 10 based on the change information of the energy storage device 10 according to the constant current switched by the measurement command unit 52. The change information of the energy storage device 10 is the same as that in the seventh embodiment, such as... Figure 22 As shown, information on the change in open-circuit voltage for a specific energy storage device 10 is stored in advance in the change information storage unit 542.

[0519] In this embodiment, the voltage change correction unit 552, similar to that in the seventh embodiment, reads the change information of the energy storage device 10 from the change information storage unit 542, and identifies the change in the open-circuit voltage of the energy storage device 10 based on the read change information. The voltage change correction unit 552 corrects the change in the measured voltage of the energy storage device 10 by subtracting the identified change in the open-circuit voltage from the change in the measured voltage of the energy storage device 10 detected by the voltage change detection unit 551, according to the magnitude of each constant current.

[0520] For example, the voltage change correction unit 552 calculates the slope of the voltage change of the open-circuit voltage of the energy storage device 10 before the constant current supply begins, based on the change information of the energy storage device 10. Then, the voltage change correction unit 552 calculates the corrected change of the measured voltage by subtracting the calculated slope of the voltage change from the change of the measured voltage detected by the voltage change detection unit 551 for each constant current magnitude.

[0521] Specifically, such as Figure 24 As shown, the voltage change correction unit 552 calculates the slope of an approximate straight line Lm0 that approximates the voltage change of the open-circuit voltage of the energy storage device 10 based on the change information stored in the change information storage unit 542. Then, the voltage change correction unit 552 calculates the slope of the approximate straight line that approximates the change of the measured voltage of the energy storage device 10 under first constant current charging by subtracting the slope of the approximate straight line Lm0 from the slope of the approximate straight line Lm1 that represents the change of the measured voltage of the energy storage device 10 under first constant current charging.

[0522] Furthermore, the voltage change correction unit 552 calculates the slope of the approximate straight line approximating the change in the measured voltage by subtracting the slope of the approximate straight line Lm0 from the slope of the approximate straight line Lm2 representing the change in the measured voltage of the energy storage device 10 charged with the second constant current. Hereinafter, the slope of the approximate straight line approximating the change in the measured voltage will be simply referred to as the "slope of the corrected measured voltage". In this way, the voltage change correction unit 552 calculates the rate of change of the corrected measured voltage according to the magnitude of each constant current.

[0523] Instead, the voltage change correction unit 552 calculates the change in open-circuit voltage per unit measurement time of the energy storage device 10 based on the change information. Furthermore, the value obtained by subtracting the calculated change from the change in measurement voltage per unit measurement time of the energy storage device 10 can also be used as the corrected change in measurement voltage.

[0524] The internal state calculation unit 553 of the controller 50C constitutes a self-discharge calculation unit, which calculates the self-discharge current Ipr or discharge resistance Rpr of the energy storage device 10 based on the change of the measured voltage of the energy storage device 10 corrected for each constant current.

[0525] In this embodiment, the internal state calculation unit 553 uses the slope of the corrected voltage change calculated for each constant current and calculates... Figure 18 The formula for the electrostatic capacitance Cst of the energy storage unit 13 shown is used to calculate the self-discharge current Ipr of the energy storage device 10. Here, the calculation method for the self-discharge current Ipr of the energy storage device 10 will be explained.

[0526] The formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the slope A1 of the corrected measured voltage when the energy storage device 10 is charged with the first constant current and the charging current Ist[A] of the energy storage unit 13. The charging current Ist[A] of the energy storage unit 13 is the amount of charge stored in the electrostatic capacitance Cst per unit time. The current Ist[A] is equivalent to the value (I1 - Ipr) obtained by subtracting the self-discharge current Ipr flowing through the parallel resistor 15 from the current value I1 of the first constant current supplied to the energy storage device 10.

[0527] Therefore, the formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10, the first current value I1, and the slope A1 of the corrected measured voltage when the energy storage device 10 is charged with the first constant current. The formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 is shown in the following formula (16).

[0528] [Formula 16]

[0529]

[0530] Similarly, the formula for calculating the electrostatic capacitance Cst of the energy storage unit 13 can be expressed as follows (17) using the self-discharge current Ipr, the second current value I2, and the slope A2 of the corrected measured voltage when the energy storage device 10 is charged with the second constant current.

[0531] [Formula 17]

[0532]

[0533] In the above formula (17), the charging current Ist[A] of the energy storage unit 13 is equivalent to the value (I2-Ipr) obtained by subtracting the self-discharge current Ipr from the current value I2 of the second constant current. However, it is shown that the current flowing through... Figure 18 The constant current of the second current value I2 of the internal resistor 14 shown is as described above, which is sufficiently greater than the self-discharge current Ipr flowing through the parallel resistor 15, and therefore can be approximated as in the following formula (18).

[0534] [Formula 18]

[0535] I2≈(I2-I pr )···(18)

[0536] Therefore, in the above formula (17), the current value I2 of the second constant current is used instead of the current value (I2 - Ipr) obtained by subtracting the self-discharge current Ipr from the current value I2 of the second constant current. Next, if the self-discharge current Ipr is solved using formulas (17) and (18), the following formula (19) is derived.

[0537] [Formula 19]

[0538]

[0539] In this way, the slopes A1 and A2 of the corrected measured voltages obtained for each constant current and the current values ​​I1 and I2 of the constant current are substituted into formulas (16) and (17) for calculating the electrostatic capacitance Cst of the energy storage unit 13. Thus, the self-discharge current Ipr of the energy storage device 10 can be calculated.

[0540] Next, the internal state calculation unit 553 calculates the discharge resistance Rpr of the energy storage device 10 based on the calculated self-discharge current Ipr.

[0541] In this embodiment, the internal state calculation unit 553 calculates the discharge resistance Rpr of the energy storage device 10 by dividing the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr of the energy storage device 10. The open-circuit voltage (OCV) of the energy storage device 10 can be the voltage value of the energy storage device 10 measured by the voltage sensor 40C before the constant current supply begins, or it can be a voltage value predetermined by using test results of the energy storage device 10, etc.

[0542] Instead, the internal state calculation unit 553 may also pre-store a correspondence table or function representing the relationship between the self-discharge current Ipr and the discharge resistance Rpr of the energy storage device 10, and use the correspondence table or function to calculate the discharge resistance Rpr.

[0543] Finally, the internal status calculation unit 553 determines whether the energy storage device 10 is normal based on the calculated discharge resistance Rpr.

[0544] In this embodiment, the internal state calculation unit 553 determines whether the calculated value of the discharge resistance Rpr of the energy storage device 10 is within a specified resistance range. The upper and lower limits of the specified resistance range are predetermined using statistical data summarizing the discharge resistance Rpr of multiple energy storage devices 10 or test results of a specific energy storage device 10 with normal electrical characteristics.

[0545] Then, if the calculated value of the discharge resistance Rpr is determined to be within the specified resistance range, the internal state calculation unit 553 determines that the energy storage device 10 is in a normal state. Conversely, if the calculated value of the discharge resistance Rpr is determined to be outside the specified range, the internal state calculation unit 553 determines that the energy storage device 10 is malfunctioning.

[0546] Alternatively, a diagnostic table representing the normal or abnormal state of the energy storage device 10 according to each discharge resistance Rpr can be pre-stored in the storage unit 54. In this case, when the discharge resistance Rpr of the energy storage device 10 is calculated, the internal state calculation unit 553 refers to the diagnostic table and establishes a specific internal state of the energy storage device 10 corresponding to the calculated discharge resistance Rpr.

[0547] It should be noted that in this embodiment, the internal state calculation unit 553 determines the condition of the energy storage device 10 based on the calculated value of the discharge resistance Rpr. However, alternatively, the calculated value of the self-discharge current Ipr can also be used to determine whether the energy storage device 10 is in a normal state. In this case, the controller 50C determines, for example, whether the calculated value of the self-discharge current Ipr is within a specified current range. When it is determined that the calculated value is within the specified current range, the energy storage device 10 is determined to be in a normal state.

[0548] Furthermore, in this embodiment, the measurement command unit 52 controls the operation of the constant current source 20C by sequentially supplying constant currents with different current values ​​to the energy storage device 10. However, if the electrostatic capacitance Cst of the energy storage unit 13 is known, it is also possible to supply only the constant current showing the first current value I1. In this case, the electrostatic capacitance Cst of the energy storage unit 13 is pre-stored in the storage unit 54. Then, the internal state calculation unit 553 substitutes the electrostatic capacitance Cst of the energy storage unit 13, the first current value I1, and the slope A1 of the corrected measurement voltage corresponding to the first current value I1 into the above formula (16) to calculate the self-discharge current Ipr.

[0549] Regarding the electrostatic capacitance Cst stored in the storage unit 54, it can be predetermined using statistical data summarizing the electrostatic capacitance Cst of the energy storage units 13 in multiple energy storage devices 10 or test results of a specific energy storage device 10. Alternatively, the internal state calculation unit 553 can charge the energy storage device 10 with a constant current showing the second current value I2, and substitute the slope A2 of the corrected measured voltage and the second current value I2 into the above formula (17) to calculate the electrostatic capacitance Cst of the energy storage unit 13.

[0550] Next, refer to Figure 26 The measurement method using the measuring apparatus 1C of the eighth embodiment will be described. Figure 26 This is a flowchart illustrating an example of a state calculation process (SC4) performed by the controller 50C of the measuring device 1C.

[0551] replace Figure 23 The processes shown in steps SC43 and SC44, the state operation process (SC4) in this embodiment includes the processes in steps SC51 to SC56. Here, only the processes in steps SC51 to SC56 will be described; for the other processes, since they are the same as in the seventh embodiment, they are given the same reference numerals and are omitted from the description.

[0552] In step SC42, controller 50C determines the value to be in Figure 20 In step SC2, the change in the measured voltage of the energy storage device 10 during constant current charging, which shows the first current value I1, is approximately approximated as a straight line Lm1, and the slope of the approximated straight line Lm1 is obtained, and then the process proceeds to step SC51.

[0553] In step SC51, the controller 50C switches the constant current supplied to the energy storage device 10 from the constant current source 20C. In this embodiment, the controller 50C switches from a first constant current to a second current value I2 that is greater than the first current value I1.

[0554] The processing of steps SC52 and SC53 is the same as that of steps SC41 and SC42, respectively. Therefore, in steps SC52 and SC53, the controller 50C measures the voltage of the energy storage device 10 under the condition of being supplied with the second constant current only at a specified time, calculates an approximate straight line Lm2 that approximates the change of the measured voltage when charging with the second constant current, and obtains the slope of the approximate straight line Lm2.

[0555] In step SC54, the controller 50C corrects the change in the measured voltage of the energy storage device 10 based on the change information of the energy storage device 10, according to the magnitude of the constant current that shows the first current value I1 and the second current value I2.

[0556] In this embodiment, such as Figure 24 As shown, the controller 50C calculates the slope of an approximate straight line Lm0, which approximates the voltage change of the open-circuit voltage of the energy storage device 10 before the constant current supply begins, based on the change information stored in the change information storage unit 542. The controller 50C calculates the slope A1 of the approximate straight line approximating the change of the measured voltage, which is approximated by the slope of the approximate straight line Lm1 when the measured voltage changes during constant current charging (shown as the first current value I1), by subtracting the slope of the approximate straight line Lm0.

[0557] Furthermore, the controller 50C calculates the slope A2 of the approximate straight line that approximates the change in the measured voltage when charging with a constant current showing the second current value I2, by subtracting the slope of the approximate straight line Lm2 from the slope of the approximate straight line Lm0. In this way, the controller 50C corrects the change in the measured voltage according to the magnitude of each constant current.

[0558] In step SC55, the controller 50C calculates the discharge resistance Rpr of the energy storage device 10 based on the slopes A1 and A2 of the approximate straight lines corrected for each constant current.

[0559] In this embodiment, the controller 50C substitutes the first current value I1, the slope A1 of the corrected approximate straight line, the second current value I2, and the slope A2 of the corrected approximate straight line into the above formula (19) to calculate the self-discharge current Ipr of the energy storage device 10. Then, the controller 50C divides the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr of the energy storage device 10 to calculate the discharge resistance Rpr of the energy storage device 10.

[0560] In step SC56, the controller 50C determines whether the energy storage device 10 is normal based on the calculated discharge resistance Rpr of the energy storage device 10.

[0561] In this embodiment, the controller 50C determines whether the calculated value of the discharge resistor Rpr is within a specified resistance range. If the calculated value of the discharge resistor Rpr is determined to be within the specified resistance range, the energy storage device 10 is in a normal state, and the controller 50C proceeds to step SC45. On the other hand, if the calculated value of the discharge resistor Rpr is determined to be outside the specified resistance range, i.e., greater than the upper limit of the resistance range or less than the lower limit of the resistance range, the energy storage device 10 is in an abnormal state, and the controller 50C proceeds to step SC46.

[0562] The condition of the energy storage device 10 is determined by performing the above state operation processing (SC4).

[0563] It should be noted that, in Figure 27 In the example shown, controller 50C switches the constant current magnitude only once and calculates the slope of the voltage change of the energy storage device 10 twice, thereby calculating the self-discharge current Ipr. Alternatively, controller 50C can switch the constant current magnitude multiple times and sequentially calculate the slope of the approximately linear change in the measured voltage, thereby calculating multiple self-discharge currents Ipr, and using the average or median value or other statistical values ​​of these as the final result.

[0564] Furthermore, in this embodiment, the controller 50C switches the magnitude of the constant current supplied from the constant current source 20C to the positive electrode 11 of the energy storage device 10 and calculates the self-discharge current Ipr, but is not limited thereto. For example, the connection relationship between the constant current source 20C and the energy storage device 10 can be reversed, and the constant current can be supplied from the constant current source 20C to the negative electrode 12 of the energy storage device 10 to discharge the energy storage device 10. In this state, the magnitude of the constant current can be switched. In this case, the self-discharge current Ipr can also be calculated as in the above embodiment.

[0565] Furthermore, in this embodiment, the magnitude of the constant current supplied to the energy storage device 10 from the constant current source 20C is switched, but even if the direction of the constant current is switched, the self-discharge current Ipr and the discharge resistance Rpr can still be calculated. Hereinafter, a method for calculating the self-discharge current Ipr of the energy storage device 10 when the direction of the constant current supplied to the energy storage device 10 is switched will be briefly explained.

[0566] The electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10 and the slope Ac of the measured voltage after correction when the energy storage device 10 is charged with a constant current showing the first current value I1, as shown in the following formula (20). Furthermore, the electrostatic capacitance Cst of the energy storage unit 13 can be expressed using the self-discharge current Ipr of the energy storage device 10 and the slope Ad of the measured voltage when the energy storage device 10 is discharged due to a constant current showing the second current value I2, as shown in the following formula (21).

[0567] [Formula 20]

[0568]

[0569] [Formula 21]

[0570]

[0571] If the self-discharge current Ipr is solved using the above formulas (20) and (21), the following formula (22) is derived.

[0572] [Formula 22]

[0573]

[0574] Therefore, by substituting the slope Ac of the corrected measured voltage during constant current charging (showing the first current value I1) and the slope Ad of the corrected measured voltage during constant current discharge (showing the second current value I2) into the above formula (22), the self-discharge current Ipr can be calculated. The discharge resistance Rpr is calculated by dividing the open-circuit voltage of the energy storage device 10 by the calculated self-discharge current Ipr.

[0575] In this case, regarding the first current value I1 and the second current value I2, at least one of their absolute values ​​can be set to one or several times the reference value of the self-discharge current Ipr. The absolute values ​​of both can be the same or different. For example, the first current value I1 can be set to 10 [μA], which is one times the reference value of the self-discharge current Ipr, and the second current value I2 can be set to the value obtained by multiplying the first current value I1 by "-1", i.e., -10 [μA]. Furthermore, regarding the slopes Ac and Ad of the voltage change, by... Figure 25 The same method is used to obtain it.

[0576] Furthermore, in this embodiment, the controller 50C switches the magnitude of the constant current, but it is also possible to switch the direction of the constant current after switching the magnitude, or vice versa. In this case, multiple self-discharge currents Ipr can be obtained, and their average value can be used as the final result.

[0577] In addition, in this embodiment, the controller 50C switches the constant current to calculate the self-discharge current Ipr of the energy storage device 10, but it is also possible to calculate the self-discharge current Ipr without switching the constant current.

[0578] For example, if the electrostatic capacitance Cst in equation (16) is known, the slope A1 of the corrected measured voltage during the first constant current charging can also be calculated. The slope A1, the first current value I1, and the known electrostatic capacitance Cst can be substituted into equation (16) to calculate the self-discharge current Ipr. Alternatively, the pre-measured or predicted values ​​can be substituted into the electrostatic capacitance Cst and the first current value I1 in equation (16) to generate a correspondence table representing the relationship between the slope A1 of the approximate straight line and the self-discharge current Ipr, which can be pre-stored in the controller 50C. In this case, when the slope A1 of the approximate straight line that approximates the corrected measured voltage is obtained, the controller 50C refers to the correspondence table to calculate the self-discharge current Ipr that is related to the slope A1 of the obtained approximate straight line.

[0579] Furthermore, as described above, the discharge resistance Rpr of the energy storage device 10 is calculated by dividing the open-circuit voltage (OCV) of the energy storage device 10 by the self-discharge current Ipr. Therefore, if the open-circuit voltage (OCV) of the energy storage device 10 is known, a correspondence table representing the relationship between the slope A1 of an approximate straight line and the discharge resistance Rpr can be generated and pre-stored in the controller 50C. In this case, when the slope A1 of an approximate straight line approximating the corrected measured voltage is obtained, the controller 50C refers to the correspondence table and calculates the discharge resistance Rpr that is related to the slope A1 of the obtained approximate straight line.

[0580] As described above, the controller 50C detects changes in one or more measured voltages of the energy storage device 10 within a short period of time, and calculates the self-discharge current Ipr or discharge resistance Rpr based on the calibrated information of the detected measured voltage changes. This ensures the accuracy of estimating the internal state of the energy storage device 10 and allows for rapid initiation of measurements of the energy storage device 10.

[0581] Next, the effects of the eighth embodiment will be explained.

[0582] In this embodiment, the controller 50C of the measuring device 1C includes a voltage change correction unit 552, which corrects for changes in the measured voltage of the energy storage device 10 based on the change information of the energy storage device 10. Furthermore, the controller 50C includes an internal state calculation unit 553, which calculates the self-discharge current Ipr or discharge resistance Rpr of the energy storage device 10 based on the corrected changes in the measured voltage of the energy storage device 10.

[0583] According to this configuration, the voltage change correction unit 552 corrects the change in the measured voltage of the energy storage device 10, thus enabling the measurement of the energy storage device 10 to start quickly. In addition, the internal state calculation unit 553 can, for example, calculate the self-discharge current Ipr or discharge resistance Rpr of the energy storage device 10 based on the corrected change in the measured voltage using the above-described formulas (16), (19), or (22).

[0584] Therefore, the measurement of the energy storage device 10 can be started quickly, and the self-discharge state of the energy storage device 10 can be determined in a short time.

[0585] Furthermore, the controller 50C in this embodiment also includes a measurement command unit 52 that switches the constant current supplied to the energy storage device 10. Then, the voltage change correction unit 552 corrects the change in the measured voltage of the energy storage device 10 based on the aforementioned change information according to each constant current switched by the measurement command unit 52. The internal state calculation unit 553 calculates the self-discharge current Ipr or discharge resistance Rpr of the energy storage device 10 based on the change in the measured voltage of the energy storage device 10 corrected according to each constant current.

[0586] Based on this configuration, the measurement command unit 52 switches the constant current, thereby obtaining the corrected measurement voltage change according to each different constant current. Therefore, for example, the self-discharge current Ipr can be calculated by using the above formula (19) or the above formula (22). In this way, by using the measured value of the energy storage device 10 as the object of measurement to obtain the parameters related to self-discharge, the error of the parameters related to self-discharge can be suppressed compared with the case of using theoretical values ​​or predicted values.

[0587] Furthermore, in this embodiment, the measurement command unit 52 switches the constant current supplied to the energy storage device 10 between a first constant current used to detect the self-discharge current Ipr and a second constant current greater than the first constant current.

[0588] According to this configuration, a second constant current greater than the first constant current is supplied to the energy storage device 10 from the constant current source 20C. Therefore, the change in the measured voltage of the energy storage device 10 becomes larger, and the slope A2 of the change in the measured voltage can be calculated with high accuracy in a short time. Moreover, the signal-to-noise ratio (S / N) of the electrical signal representing the voltage detected by the voltage sensor 40C becomes higher, thus improving the accuracy of calculating the slope A2 of the change in the measured voltage.

[0589] For example, in the open circuit voltage of the energy storage device 10, such as Figure 22 In the case of the variation shown, if the change in the measured voltage is not corrected, the calculated value of the discharge resistance Rpr will be about one-tenth of the true value. In contrast, by correcting the change in the measured voltage as in this embodiment, even when the energy storage device 10 itself experiences voltage fluctuations, the calculated value of the discharge resistance Rpr can be made close to the true value.

[0590] (Ninth Implementation)

[0591] Next, refer to Figure 27 The measuring device 2C of the ninth embodiment will be described. Figure 27 This is a diagram showing the configuration of the measuring device 2C. Besides... Figure 18 In addition to the configuration shown, the measuring device 2C also includes a reference voltage source 30C. Regarding other configurations, since... Figure 18 The structures shown are identical, therefore the same reference numerals are used and descriptions are omitted.

[0592] The reference voltage source 30C constitutes a voltage generation unit, generating a reference voltage relative to the voltage of the energy storage device 10. The reference voltage source 30C is, for example, composed of a voltage generation circuit. For example, when the voltage of the energy storage device 10 is about 3 [V], the reference voltage of the reference voltage source 30C relative to the voltage of the energy storage device 10 is set in the range from "-1V" to "+1V".

[0593] Voltage sensor 40C measures the potential difference between the measured voltage and the reference voltage of the energy storage device 10 under constant current supply. That is, voltage sensor 40C indirectly measures the change in the measured voltage of the energy storage device 10. Voltage sensor 40C outputs an electrical signal representing the measured potential difference to controller 50C.

[0594] Regarding the controller 50C, it is basically the same as Figure 19 The functions shown are identical and can be executed. Figure 20 and Figure 23 The measurement method of the seventh embodiment shown or Figure 20 and Figure 26 The measurement method of the eighth embodiment shown.

[0595] The controller 50C corrects for changes in the measured potential difference based on the change information of the energy storage device 10 and the potential difference between the voltage supplied to the energy storage device 10 with constant current and the reference voltage. Then, it constructs an arithmetic unit to calculate the internal state of the energy storage device 10 based on the corrected change in potential difference.

[0596] In this embodiment, the controller 50C detects the time change of the measured voltage of the energy storage device 10 based on the electrical signal output from the voltage sensor 40C, and corrects the detected time change of the measured voltage based on the change information of the energy storage device 10. Then, the controller 50C determines the internal state or self-discharge state of the energy storage device 10 based on the corrected time change of the measured voltage.

[0597] At this time, as variable information, measured data representing the time change of the potential difference between the open-circuit voltage of the energy storage device 10 and the reference voltage before or after the measurement is started can be used. Alternatively, measured data, statistical data, theoretical data, or simulation results representing the time change of the open-circuit voltage of the energy storage device 10 itself before or after the measurement can also be used.

[0598] According to the ninth embodiment, the measuring device 2C in this embodiment further includes a reference voltage source 30C, which generates a reference voltage relative to the voltage of the energy storage device 10. The voltage sensor 40C measures the potential difference between the measured voltage of the energy storage device 10 and the reference voltage as the measured voltage of the energy storage device 10. Furthermore, the controller 50C calculates the internal state of the energy storage device 10 based on the change in potential difference corrected according to the change information of the energy storage device 10.

[0599] According to this configuration, by measuring the potential difference between the measured voltage of the energy storage device 10, which is supplied with a constant current from the constant current source 20C, and the reference voltage of the reference voltage source 30C, a portion of the DC component of the voltage of the energy storage device 10 is removed. This improves the resolution of the voltage sensor 40C. Consequently, the influence of internal noise in the voltage sensor 40C is reduced, thus shortening the measurement time.

[0600] In addition, by correcting for changes in the measured voltage difference, the resolution of the voltage sensor 40C can be improved, thereby accurately removing environmentally-induced variations that are easily manifested in changes in the measured potential difference. This reduces environmentally-induced variations in the energy storage device 10 and improves the resolution of the voltage sensor 40C, thus enabling high-precision detection of changes in the measured voltage of the energy storage device 10.

[0601] In the ninth embodiment, the reference voltage source 30C is composed of a voltage generation circuit, but the reference voltage source 30C may also be composed of other energy storage devices of the same type as the energy storage device 10. By measuring the potential difference between the energy storage device 10 and other energy storage devices under the same environment, the voltage fluctuation component accompanying the temperature change of the energy storage device 10 is removed, thereby improving the detection accuracy of voltage changes caused by different internal states of the energy storage device 10.

[0602] The seventh to ninth embodiments have been described above, but the above embodiments only illustrate a part of the application examples of the present invention, and are not intended to limit the scope of the technology of the present invention to the specific configuration of the above embodiments.

[0603] For example, the degree of voltage change in the energy storage device 10 varies depending on the internal temperature of the energy storage device 10. This property is utilized to pre-store a temperature gauge representing the relationship between the voltage change and the internal temperature of the energy storage device 10 in the controller 50C. The controller 50C can also estimate the internal temperature of the energy storage device 10 based on the measured voltage change of the calibrated energy storage device 10.

[0604] Furthermore, in the above embodiment, the self-discharge current Ipr and discharge resistance Rpr are calculated using the corrected voltage change of the energy storage device 10. However, alternatively or otherwise, the electrostatic capacitance Cst of the energy storage unit 13 can also be calculated. For example, the electrostatic capacitance Cst of the energy storage unit 13 can be calculated by substituting the slope A2 of the corrected voltage change when the energy storage device 10 is charged with a constant current representing the second current value I2 and the second current value I2 into the above formula (17).

[0605] In addition, the controller 50C can also determine the internal state of the energy storage device 10 based on the calculated electrostatic capacitance Cst. For example, the controller 50C determines whether the energy storage device 10 is in good condition by determining whether the calculated value of the electrostatic capacitance Cst is within the specified normal range.

[0606] Furthermore, while the internal state of a single energy storage device 10 was measured in the above embodiment, the internal state of an energy storage module in which multiple energy storage devices 10 are connected in series can also be measured. Furthermore, in Figure 18 and Figure 27 The measuring devices 1C and 2C shown include a display unit 60C and an operation unit 70C, but at least one of the display unit 60C and the operation unit 70C may be omitted.

[0607] The measuring devices 1, 1A, 1B, 1C, 2B, and 2C in the first to ninth embodiments function as devices for detecting voltage changes in the energy storage device 10, as described above. These devices supply a constant current to the energy storage device 10, measure the voltage associated with the supplied constant current, and detect the measured voltage change in the energy storage device 10. Then, these devices acquire the voltage change of the energy storage device 10 based on electrical characteristics that serve as a reference for the energy storage device 10.

[0608] This application claims priority based on Japanese Patent Application Nos. 2020-006174, 2020-006176 and 2020-006179, filed with the Japan Patent Office on January 17, 2020, the entire contents of which are incorporated herein by reference.

[0609] Explanation of reference numerals in the attached figures:

[0610] 1, 1A, 1B, 1C, 2B, 2C: Measuring device;

[0611] 10, 10A: Energy storage equipment;

[0612] 13: Battery Storage Unit;

[0613] 14: Internal resistance;

[0614] 15: Parallel resistors;

[0615] 20, 20B, 20C: Constant current source (supply unit);

[0616] 30, 30A: Reference voltage source (voltage generation unit);

[0617] 40, 40B, 40C: Voltmeter, voltage sensor (measuring unit);

[0618] 50, 50B, 50C: Controller (processing unit, arithmetic unit);

[0619] S2, S3, S4: (Measurement step, supply step, processing step);

[0620] SB1, SB4, SB5, SB6: (Determination step, supply step, measurement step, calculation step).

Claims

1. A measuring device for an energy storage device, which measures the state of the energy storage device by acquiring the voltage change of the energy storage device based on electrical characteristics that serve as a reference for the energy storage device, comprising: The supply unit supplies constant current to the energy storage device; The measuring unit measures the voltage associated with the energy storage device to which the constant current is supplied; The processing unit detects and measures the voltage change of the energy storage device; as well as The voltage generation unit generates a reference voltage relative to the voltage of the energy storage device as the electrical characteristic. The processing unit includes a calculation unit that performs calculations on the internal state of the energy storage device based on the detected voltage changes. The measuring unit measures the potential difference between the voltage of the energy storage device and the reference voltage. The processing unit detects the change in the measured potential difference as the voltage change.

2. The measuring device for energy storage equipment according to claim 1, wherein, The measuring unit includes: A resistive element is connected between the energy storage device and the positive terminal of the voltage generation unit; and The component detection unit detects the voltage generated by the resistive element as the potential difference.

3. The measuring device for energy storage equipment according to claim 2, wherein, The current flowing through the resistive element is less than the constant current.

4. The measuring device for energy storage equipment according to claim 2 or 3, wherein, The reference voltage is set such that the voltage generated by the resistive element is less than the voltage of the energy storage device.

5. The measuring device for energy storage equipment according to claim 4, wherein, The voltage generation unit includes other energy storage devices.

6. The measuring device for an energy storage device according to any one of claims 1 to 3, wherein, The computing unit generates information related to the self-discharge state of the energy storage device based on the measured change in the potential difference.

7. The measuring device for energy storage equipment according to claim 6, wherein, The information includes at least one of internal information representing the self-discharge current or discharge resistance of the energy storage device and information indicating whether the energy storage device is good or bad.

8. The measuring device for energy storage equipment according to claim 1, wherein, When the voltage of the energy storage device is a predetermined value based on the electrical characteristics, the supply unit supplies a constant current to the energy storage device. The specified value is determined based on data relating the voltage of a particular energy storage device to the electrostatic capacitance component of the energy storage device.

9. The measuring device for energy storage equipment according to claim 8, wherein, The specified value is set as the voltage value of the energy storage device when the voltage of the energy storage device changes due to discharge or charging, and the electrostatic capacitance component of the energy storage device is lower than a threshold value.

10. The measuring device for energy storage equipment according to claim 9, wherein, The threshold is set based on the maximum or average value of the electrostatic capacitance component of the energy storage device.

11. The measuring device for energy storage equipment according to claim 1, wherein, The measuring device includes: an acquisition unit that acquires information on the variation of the open-circuit voltage of a specific energy storage device as the electrical characteristic. The arithmetic unit has the following features: The detection unit detects changes in the measured voltage based on the measured voltage of the energy storage device as measured by the measurement unit. as well as The calibration unit corrects for changes in the detected measurement voltage based on the information.

12. The measuring device for energy storage equipment according to claim 11, wherein, The measuring unit measures the open-circuit voltage of the energy storage device and outputs a signal representing the magnitude of the open-circuit voltage as the information, and then measures the measuring voltage of the energy storage device supplied with the constant current.

13. The measuring device for energy storage equipment according to claim 11 or 12, wherein, The correction unit corrects the change in the measured voltage by subtracting the change in the open-circuit voltage specific to the information from the change in the measured voltage detected by the detection unit.

14. The measuring device for energy storage equipment according to claim 11 or 12, wherein, The arithmetic unit has the following features: The self-discharge calculation unit calculates the self-discharge current or discharge resistance of the energy storage device based on the corrected change in the measured voltage.

15. The measuring device for energy storage equipment according to claim 14, wherein, The measuring device further includes: a switching unit for switching the constant current supplied to the energy storage device. The correction unit corrects for changes in the measured voltage of the energy storage device based on the information, according to the constant current switched by the switching unit for each change. The self-discharge calculation unit calculates the self-discharge current or discharge resistance based on the change in each constant current-corrected measured voltage.

16. The measuring device for energy storage equipment according to claim 15, wherein, The switching unit switches the constant current supplied to the energy storage device between a first constant current used to detect the self-discharge current and a second constant current greater than the first constant current.

17. The measuring device for energy storage equipment according to claim 11 or 12, wherein, The measuring device further includes: a voltage generation unit that generates a reference voltage relative to the voltage of the energy storage device. The measuring unit measures the potential difference between the voltage of the energy storage device and the reference voltage as the measuring voltage. The computing unit calculates the internal state of the energy storage device based on the corrected change in the potential difference.

18. A method for measuring an energy storage device, comprising: obtaining voltage changes of the energy storage device based on electrical characteristics serving as a reference for the energy storage device, and measuring the state of the energy storage device, comprising: In the supply step, a constant current is supplied to the energy storage device; The measurement step involves measuring the voltage associated with the energy storage device to which the constant current is supplied; The processing steps include detecting and measuring the voltage change of the energy storage device; and The voltage generation step generates a reference voltage relative to the voltage of the energy storage device, which serves as the reference electrical characteristic for the energy storage device. In the measurement step, the potential difference between the voltage of the energy storage device and the reference voltage is measured. In the processing step, the measured change in potential difference is detected as the voltage change.

19. The method for measuring energy storage devices according to claim 18, wherein, The measurement method includes: a determination step, which determines the voltage value when measuring the state of the storage device based on the relationship between the voltage of the storage device and the electrostatic capacitance component of the storage device in the electrical characteristics. In the supply step, when the voltage of the energy storage device is the stated voltage value, a constant current is supplied to the energy storage device. In the processing step, the internal state of the energy storage device is calculated based on the measured voltage change of the energy storage device.

20. The method for measuring energy storage devices according to claim 19, wherein, In the determination step, the voltage value is determined in a manner that avoids a specific voltage value near which the electrostatic capacitance component of the energy storage device is at its maximum, within a range where the voltage of the energy storage device varies due to discharge or charging.

21. The method for measuring energy storage devices according to claim 19 or 20, wherein, In the determining step, the voltage value is made to be lower than the maximum specific voltage value of the electrostatic capacitance component of the energy storage device.

22. The method for measuring energy storage devices according to claim 19 or 20, wherein, The determination method comprises: The control steps involve controlling the charging or discharging of the energy storage device. The control measurement step involves measuring the voltage of the energy storage device during the control process. as well as The generation step involves generating data for a specific relationship based on the measured voltage of the energy storage device.

23. The method for measuring energy storage devices according to claim 19 or 20, wherein, In the determining step, the voltage value is determined based on the time for detecting the voltage change of the energy storage device supplied with the constant current or the amount of voltage change required for detection.

24. The method for measuring energy storage devices according to claim 18, wherein, The measurement method includes: an acquisition step, which acquires information on the variation of the open-circuit voltage of a specific energy storage device as the electrical characteristic. In the processing step, the measured voltage change of the energy storage device is corrected based on the information, and the internal state of the energy storage device is calculated based on the corrected voltage change.

25. The method for measuring energy storage devices according to claim 18, wherein, The measurement method includes: a generation step, which generates a reference voltage relative to the voltage of the energy storage device as a reference. In the measurement step, the potential difference between the voltage of the energy storage device and the reference voltage is measured. In the processing step, the measured change in potential difference is taken as the voltage change. The internal state of the energy storage device is calculated based on the detected change in the potential difference.

Images