Electronic equipment and measurement method

Abstract

An electronic apparatus according to one aspect of the present technology is provided with a voltage difference deriving unit for deriving, on the basis of a voltage value obtained by means of voltage measurement, a difference between a first voltage value, which is the voltage value before a current is changed in a stepwise manner, and a second voltage value, which is the voltage value after the current has been changed in a stepwise manner. The voltage difference deriving unit derives at least two of the following three differences. ∙ A first difference between the first voltage value and a third voltage value, which is the voltage value after a component of the second voltage value originating from a bulk resistance of a battery has changed ∙ A second difference between the first voltage value and a fourth voltage value, which is the voltage value after a component of the second voltage value originating from a charge transfer resistance of the battery has changed ∙ A third difference between the first voltage value and a fifth voltage value, which is the voltage value after a component of the second voltage value originating from a diffusion resistance of the battery has changed

Description

[Technical Field]

[0001] The present technology relates to electronic devices and measurement methods. [Background technology]

[0002] In recent years, the use of secondary batteries has expanded to larger-scale devices such as electric vehicles and energy storage systems. As the scale of these devices increases, the damage caused by fire also increases, making it increasingly important to develop technologies to improve safety. Furthermore, it is important to properly understand abnormal behavior and deterioration of secondary batteries.

[0003] In Patent Document 1, the current is interrupted during charging and discharging, and the presence or absence of degradation is detected from the amount of voltage change at that time. Here, in Patent Document 1, the presence or absence of degradation is detected by comparing the amount of voltage change in the initial state with the amount of voltage change during use, that is, by relative evaluation. Therefore, compared to when performing absolute evaluation, it does not require many experiments to define evaluation criteria for degradation (for example, threshold values), realizing excellent operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-176924 Summary of the Invention

[0005] However, Patent Document 1 has a problem in that it is difficult to make a multifaceted judgment as to what kind of deterioration has specifically occurred. It is desirable to provide an electronic device and a measurement method that enable a multifaceted judgment.

[0006] An electronic device according to a first aspect of the present technology includes a current supply unit, a voltage measurement unit, and a voltage difference derivation unit. The current supply unit is capable of supplying a current that changes stepwise to a battery. The voltage measurement unit measures the voltage of the battery. The voltage difference derivation unit is capable of deriving a difference between a first voltage value, which is a voltage value before the current supply unit changes the current stepwise, and a second voltage value, which is a voltage value after the current supply unit changes the current stepwise, based on a voltage value obtained by measurement by the voltage measurement unit. The voltage difference derivation unit is capable of deriving at least two of the following three differences: a first difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed at the second voltage value; A second difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery at the second voltage value has changed. A third difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed at the second voltage value.

[0007] Measurement methods according to the second aspect of the present technology include the following three methods. (A) Supplying a step-like current to the battery (B) Measuring the battery voltage (C) Deriving, based on the voltage value obtained by the measurement, a difference between a first voltage, which is a voltage value before the current flowing to the battery is changed in a stepwise manner, and a second voltage, which is a voltage value after the current flowing to the battery is changed in a stepwise manner in the current supply process. When deriving the difference, derive at least two of the following three differences: a first difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed at the second voltage value; A second difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery at the second voltage value has changed. A third difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed at the second voltage value.

[0008] According to an electronic device according to a first aspect of the present technology and a measurement method according to a second aspect of the present technology, a difference between a first voltage, which is a voltage value before a current flowing through a battery is changed stepwise, and a second voltage, which is a voltage value after the current flowing through the battery is changed stepwise, is derived based on a voltage value obtained by voltage measurement. When deriving this difference, at least two of the following three differences are derived, so that at least two circuit constants in the battery's equivalent circuit can be derived using the at least two derived differences. As a result, the at least two derived circuit constants can be used to make a multifaceted judgment about the battery's degradation mode.

[0009] Note that the effects of the present technology are not necessarily limited to the effects described here, but may be any of a series of effects related to the present technology described below. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of functional blocks of an analysis device according to an embodiment of the present technology. [Figure 2] 2A is a diagram showing an example of the waveform of the current supplied to the battery, and FIG. 2B is a diagram showing an example of the waveform of the battery voltage. [Figure 3] FIG. 3 is a diagram showing an equivalent circuit of a secondary battery that is the subject of analysis by the analysis device of FIG. [Figure 4] FIG. 4 is a diagram showing an example of an analysis procedure in the analysis device of FIG. [Figure 5] FIG. 5 is a diagram showing an example of the analysis result obtained by the analysis device of FIG. [Figure 6] FIG. 6 is a diagram showing an example of the analysis result obtained by the analysis device of FIG. [Figure 7] FIG. 7 is a diagram showing an example of the analysis result obtained by the analysis device of FIG. [Figure 8] FIG. 8 is a diagram showing an example of the analysis result obtained by the analysis device of FIG. [Figure 9]FIG. 9 is a diagram illustrating a modified example of the functional blocks of the analysis device according to an embodiment of the present technology. [Figure 10] FIG. 10 is a diagram illustrating a modified example of the functional blocks of the analysis device according to an embodiment of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings.

[0012] <1. Embodiment> [composition] A configuration of an analysis device 10 according to an embodiment of the present technology will be described. The analysis device 10 is a device that analyzes the degradation state of a secondary battery. In this embodiment, a secondary battery to be analyzed by the analysis device 10 is an assembled battery 20. The assembled battery 20 is, for example, a lithium ion secondary battery. The assembled battery 20 is configured to include a plurality of single cells 21. Each single cell 21 may be a unit cell or a battery block in which a plurality of unit cells are connected. In each single cell 21, a plurality of secondary batteries may be connected in series, or a plurality of secondary batteries may be connected in parallel.

[0013] The analysis device 10 includes, for example, a current supply unit 11, a voltage measurement unit 12, a current measurement unit 13, a voltage difference derivation unit 14, a circuit constant calculation unit 15, and a multivariate analysis unit 16, as shown in FIG.

[0014] The current supply unit 11 is a device that discharges and charges the assembled battery 20 installed in the analysis device 10. The current supply unit 11 is capable of charging, for example, CCCV charging. For example, in CCCV charging, the current supply unit 11 changes the current supplied to the assembled battery 20 in steps (current supply step S102 in FIG. 4). The current supply unit 11 has a charging circuit that includes, for example, a generator and a converter. This charging circuit controls the voltage for charging the assembled battery 20.

[0015] The voltage measurement unit 12 has a measurement circuit that measures the voltage of each cell 21 included in the assembled battery 20. Note that FIG. 1 illustrates a configuration in which wiring is connected to the positive and negative electrodes of each cell 21, and the voltage of each cell 21 is measured by measuring the voltage obtained through the wiring, but the method for measuring the voltage of each cell 21 is not limited to this method. The voltage measurement unit 12 outputs data (voltage values) about the voltage measured by the measurement circuit to the voltage difference derivation unit 14. The voltage measurement unit 12 measures the voltage of each cell 21 during and after charging or discharging the assembled battery 20 (first voltage measurement step S101 and second voltage measurement step S103 in FIG. 4).

[0016] The current measurement unit 13 has a measurement circuit that measures the current of each cell 21 included in the battery pack 20. Note that while FIG. 1 illustrates a configuration in which wiring is connected to the positive and negative electrodes of the battery pack 20 and the current of each cell 21 is measured by measuring the current acquired through the wiring, the method for measuring the current of each cell 21 is not limited to this method. The current measurement unit 13 outputs data (current value) on the current measured by the measurement circuit to the voltage difference derivation unit 14. The current measurement unit 13 measures the current of each cell 21 (i.e., the current of the battery pack 20) ​​during and after charging or discharging the battery pack 20.

[0017] Based on the voltage value obtained by measurement by the voltage measurement unit 12, the voltage difference derivation unit 14 derives, for each cell 21, the difference between the voltage value Vo (first voltage value) before the current supply unit 11 changes the current stepwise and the voltage value (second voltage value) after the current supply unit 11 changes the current stepwise (voltage difference derivation step S104 in FIG. 4). Specifically, the voltage difference derivation unit 14 derives at least two of the following three differences for each cell 21, as shown in FIG. 2. The voltage difference derivation unit 14 derives, for example, (1) the difference Va and the difference Vc, (2) the difference Vb and the difference Vc, or (3) the difference Va, the difference Vb, and the difference Vc for each cell 21. A difference Va (first difference) between the voltage value Vo and the voltage value V1 (third voltage value) after the component attributable to the bulk resistance of the cell 21 has changed in the second voltage value (Va=|Vo−V1|). A difference Vb (second difference) between the voltage value Vo and the voltage value V2 (fourth voltage value) after the component attributable to the charge transfer resistance of the cell 21 at the second voltage value has changed (Vb=|Vo−V2|). A difference Vc (third difference) between the voltage value Vo and the voltage value V3 (fifth voltage value) after the component attributable to the diffusion resistance of the battery 21 has changed in the second voltage value (Vc=|Vo−V3|).

[0018] The voltage difference derivation unit 14 derives the difference Va by setting the voltage value within a period of 1 μs or more and less than 1 ms after the current supply unit 11 changes the current stepwise as the voltage value V1. The voltage difference derivation unit 14 derives the difference Vb by setting the voltage value within a period of 1 ms or more and less than 10 s after the current supply unit 11 changes the current stepwise as the voltage value V2. The voltage difference derivation unit 14 derives the difference Vc by setting the voltage value within a period of 10 s or more and less than 100,000 s after the current supply unit 11 changes the current stepwise as the voltage value V2.

[0019] The circuit constant calculation unit 15 calculates at least two circuit constants of the equivalent circuit of each battery 21 using the voltage values ​​and current values ​​during charging or discharging (before the current is changed in a stepwise manner) and after charging or discharging (after the current is changed in a stepwise manner) for each battery 21, which are derived by the voltage difference derivation unit 14 (circuit constant calculation step S105 in Figure 4).

[0020] Fig. 3 shows an equivalent circuit of each cell 21. As shown in Fig. 3, each cell 21 is represented by an equivalent circuit consisting of a bulk resistance Rs with a time constant τa of 1 μs or more and less than 1 ms, a charge transfer resistance Rct with a time constant τb of 1 ms or more and less than 10 s, and a diffusion resistance Rd with a time constant τc of 10 s or more and less than 100,000 s.

[0021] The circuit constant calculation unit 15 calculates the bulk resistance Rs (impedance parameter) by dividing the difference Va by the current value Io during charging or discharging (before the current is changed stepwise). The circuit constant calculation unit 15 calculates the sum (impedance parameter) of the bulk resistance Rs and the charge transfer resistance Rct by dividing the difference Vb by the current value Io. The circuit constant calculation unit 15 calculates the sum (impedance parameter) of the bulk resistance Rs, the charge transfer resistance Rct, and the diffusion resistance Rd by dividing the difference Vc by the current value Io.

[0022] Here, the bulk resistance Rs, the charge transfer resistance Rct, and the diffusion resistance Rd generally have the following relationship: Rs <Rct<Rd Therefore, the circuit constant (impedance parameter) calculated using the difference Vb is mainly due to the charge transfer resistance Rct. Meanwhile, the circuit constant (impedance parameter) calculated using the difference Vc is mainly due to the diffusion resistance Rd. Therefore, the three circuit constants (impedance parameters) calculated by the circuit constant calculation unit 15 are not completely independent of each other, but can be said to be highly independent of each other. Therefore, it is possible to determine from the three circuit constants (impedance parameters) calculated by the circuit constant calculation unit 15 whether the deterioration of the cell 21 is expected or abnormal.

[0023] The multivariate analysis unit 16 derives distribution information of at least two circuit constants (impedance parameters) for the plurality of cells 21 and performs multivariate analysis using the distribution information thus obtained (multivariate analysis step S106 in FIG. 4). The multivariate analysis unit 16 uses, for example, the Mahalanobis-Taguchi method or the one-class support vector machine method as a multivariate analysis method. Multivariate analysis using the Mahalanobis-Taguchi method will be described in detail below. The multivariate analysis unit 16 derives the degree of anomaly ai for each cell 21, for example, by performing the following multivariate analysis.

[0024] (Preparation of the lithium-ion battery sample) Fifteen commercially available US18650FTC1 lithium-ion batteries (rated capacity 1.05 Ah) were prepared. These batteries were made of lithium iron phosphate (LiFePO4, LFP) as the primary cathode active material and graphite as the primary anode active material. All batteries were from the same production lot. Twelve of these batteries were first discharged at a constant current equivalent to a 0.2-hour rate until the voltage fell below 2.0 V. (The rated capacity was 1.05 Ah, and the current value I per hour was 1.05 A, so the current value I per hour was 0.2 I = 210 mA.) They were then immediately subjected to CCCV charging at a set current of 1.05 A (= 1 It) and a set voltage of 3.6 V. This two-step charging process involved constant current charging at a set current until the set voltage was reached, followed by constant voltage charging once the set voltage was reached. The charging process was stopped 2.5 h after the start of the charging process. While maintaining a fully charged state, each of the 12 lithium-ion batteries was placed in a thermostatic chamber set to one of 12 different temperatures: 35°C, 40°C, ..., 90°C, and left there for 25 days to deteriorate.

[0025] (Calculation of circuit constants) Of the 15 lithium-ion batteries prepared, the following voltage difference measurements were performed three times for each of the three lithium-ion batteries that had not undergone the above-mentioned degradation process, and only once for each of the 12 lithium-ion batteries that had undergone the above-mentioned degradation process.

[0026] The sample was placed in a thermostatic chamber at 23°C and subjected to CCCV charging at a set current of 1.05 A (1 It) and a set voltage of 3.6 V. CCCV charging was stopped when the current during constant-voltage charging fell below 105 mA (0.1 It). The current Io immediately before the current was interrupted was 105 mA. The voltage immediately before the current was interrupted was measured and designated Vo. The voltages 0.6 ms, 60 ms, and 1 h after the current was interrupted were also measured and designated V1, V2, and V3, respectively. The first voltage difference divided by the current (V1 - Vo) / Io was calculated as Rs. The second voltage difference divided by the current and further subtracted Rs (V2 - Vo) / Io - Rs was calculated as Rct. The third voltage difference divided by the current (V3 - Vo) / Io was calculated as Rdc. Rdc is the sum of the bulk resistance Rs, charge transfer resistance Rct, and diffusion resistance Rd.

[0027] (Multivariate analysis) For three lithium-ion batteries that had not undergone the above-mentioned degradation process, AC impedance measurements were performed three times for each battery. The nine sets of data (each containing three circuit constants (impedance parameters)) were then defined as nine vectors xi (where i is an integer from 1 to 9) as shown in the following equation (1).

number

[0028] Next, the average vector μ of the nine sets of data for each circuit constant and the variance-covariance matrix Σ were calculated using equations (2) and (3), respectively.

number

number

[0029] Next, 12 sets of data (each containing three circuit constants (impedance parameters)) obtained from 12 lithium-ion batteries that had undergone the above-mentioned degradation process were defined as 12 additional vectors xi (where i is an integer between 10 and 21) as shown in equation (4). Then, the degree of anomaly ai was calculated for all 21 vectors in total according to equation (5).

number

number

[0030] For comparison, we also calculated the degree of abnormality using only one circuit constant rather than multiple variables (Figures 5 to 7). In addition, for all results, we calculated thresholds for determining whether or not a result was abnormal from the 95th and 99th percentiles in the F distribution table.

[0031] Figure 8 shows the results of the anomaly calculation using three circuit constants (impedance parameters). In both figures, "A" through "I" on the horizontal axis represent data obtained from batteries that did not undergo the aforementioned degradation process, corresponding to i = 1, 2, ..., 9 in Equation (5). Also, "J" through "U" on the horizontal axis represent data obtained from batteries that did undergo the aforementioned degradation process, corresponding to i = 10, 11, ..., 21 in Equation (5). Because "A" through "I" did not undergo the aforementioned degradation process, in the following discussion, these are considered to be data obtained from good (normal) batteries. On the other hand, "J" through "U" represent data obtained from batteries stored at temperatures of 35°C, 40°C, ..., and 90°C, respectively. The closer to Z, the greater the degree of degradation. All of these are considered to be data obtained from defective batteries.

[0032] 5 and 6, no clear difference in the degree of abnormality was observed between the batteries "A" to "I" that were deemed to be good products and the batteries "J" to "U" that were deemed to be bad products. In other words, it was found that it is not possible to determine whether a product is good or bad using only Rs or Rct.

[0033] Figure 7 shows that there is a tendency for the defective batteries to have a higher degree of abnormality than the batteries "A" to "I" that were deemed to be good products, and "J" to "U" that were deemed to be defective products. However, a relatively high degree of abnormality was detected in "C" and "F" that were deemed to be good products. In other words, it was found that the accuracy is insufficient when attempting to determine whether a product is good or defective using only Rdc.

[0034] Figure 8 shows a clear tendency that the defective batteries have a higher degree of abnormality than the non-defective batteries "A" to "I" and the defective batteries "J" to "S." In other words, it was found that it is possible to make an accurate judgment by using three circuit constants (impedance parameters).

[0035] For the above reasons, the multivariate analysis unit 16 selects at least two circuit constants (impedance parameters) for the plurality of cells 21 in the multivariate analysis, and includes at least circuit constants (impedance parameters) related to the physical phenomenon that causes the transient response. The above-mentioned three circuit constants (impedance parameters) are examples of such circuit constants.

[0036] [effect] Next, the effects of the analysis device 10 will be described.

[0037] In recent years, the use of secondary batteries has expanded to larger-scale devices such as electric vehicles and energy storage systems. As the scale of these devices increases, the damage caused by fire also increases, making it increasingly important to develop technologies that improve safety. Furthermore, it is important to properly monitor abnormal behavior and degradation of secondary batteries during use.

[0038] In Patent Document 1, the current is interrupted during charging and discharging, and the presence or absence of degradation is detected from the amount of voltage change at that time. Here, in Patent Document 1, the presence or absence of degradation is detected by comparing the amount of voltage change in the initial state with the amount of voltage change during use, that is, by relative evaluation. Therefore, compared to when performing absolute evaluation, it does not require many experiments to define evaluation criteria for degradation (for example, threshold values), realizing excellent operation.

[0039] On the other hand, in the present embodiment, a difference between a voltage value Vo (first voltage value) before the current flowing through the cell 21 is changed stepwise and a voltage value (second voltage value) after the current flowing through the cell 21 is changed stepwise is derived based on the voltage value measured by the voltage measurement unit 12. When deriving this difference, at least two of the three differences Va, Vb, and Vc described above are derived. As a result, at least two circuit constants (impedance parameters) in the equivalent circuit of the cell 21 can be derived using the at least two derived differences. As a result, a multifaceted determination of the degradation mode of the cell 21 can be made using the at least two derived circuit constants (impedance parameters).

[0040] In this embodiment, for example, as shown in FIG. 9, multivariate analysis unit 16 may perform multivariate analysis using distribution information stored in storage unit 17 instead of distribution information of at least two circuit constants (impedance parameters) in a plurality of single cells 21. The distribution information stored in storage unit 17 is distribution information of at least two circuit constants (impedance parameters) in a plurality of normal batteries. Storage unit 17 is, for example, configured with a nonvolatile memory, such as an EEPROM (Electrically Erasable Programmable Read-Only Memory), a flash memory, or a resistance change memory.

[0041] In this case, the two or more circuit constants (impedance parameters) for the plurality of normal batteries selected in the multivariate analysis include, for example, at least two of the three circuit constants (impedance parameters) described above. The at least two circuit constants (impedance parameters) for the plurality of single cells 21 selected in the multivariate analysis include, for example, (1) Rs and Rd, (2) Rct and Rd, or (3) Rs, Rct, and Rd.

[0042] In this embodiment, the secondary battery to be analyzed by the analysis device 10 may be, for example, a cell 30 as shown in FIG. 10. In this case, the cell 30 may be a unit cell or a battery block in which a plurality of unit cells are connected. In the cell 30, a plurality of secondary batteries may be connected in series, or a plurality of secondary batteries may be connected in parallel. In this case, the multivariate analysis unit 16 may perform multivariate analysis using distribution information stored in the memory unit 17 instead of distribution information of at least two circuit constants (impedance parameters) in a plurality of cells 21, as shown in FIG. 10. The distribution information stored in the memory unit 17 is distribution information of at least two circuit constants (impedance parameters) in a plurality of normal batteries.

[0043] The effects described in this specification are merely examples, and the effects of the present technology are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present technology.

[0044] The present technology can also be configured as follows. <1> a current supply unit capable of supplying a current that changes stepwise to the battery; a voltage measurement unit capable of measuring the voltage of the battery; a voltage difference derivation unit that is capable of deriving a difference between a first voltage value, which is the voltage value before the current supply unit changes the current stepwise, and a second voltage value, which is the voltage value after the current supply unit changes the current stepwise, based on a voltage value obtained by measurement by the voltage measurement unit; Equipped with The voltage difference deriving unit is capable of deriving at least two of the following three differences: electronic equipment. a first difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed in the second voltage value; A second difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery has changed in the second voltage value. a third difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed in the second voltage value; <2> The voltage difference derivation unit is capable of deriving the first difference by using a voltage value within a period of 1 μs or more and less than 1 ms after the current supply unit changes the current stepwise as the third voltage value. <1> The electronic device described in <3> The voltage difference derivation unit is capable of deriving the second difference by using a voltage value within a period of 1 ms or more and less than 10 s after the current supply unit changes the current stepwise as the fourth voltage value. <1> The electronic device described in <4> The voltage difference derivation unit is capable of deriving the third difference by using a voltage value within a period of 10 seconds or more and less than 10,000 seconds after the current supply unit changes the current stepwise as the fifth voltage value. <1> The electronic device described in <5> the battery is a single cell, a current measuring unit capable of measuring the current of the battery; a calculation unit that is capable of calculating at least two circuit constants of an equivalent circuit of the battery using a current value obtained by measurement by the current measurement unit, the current value being before the current is changed in a stepwise manner by the current supply unit, and at least two of the first difference, the second difference, and the third difference; an analysis unit capable of performing multivariate analysis using distribution information of the at least two circuit constants in a plurality of normal batteries; Equipped with <1> The electronic device described in <6> the battery is a battery pack including a plurality of single cells, the voltage measurement unit is capable of measuring the voltages of the plurality of cells included in the battery pack, The voltage difference deriving unit is capable of deriving the difference for each of the unit cells. <1> The electronic device described in <7> a current measuring unit capable of measuring the current of the plurality of single cells; a calculation unit that is capable of calculating at least two circuit constants of an equivalent circuit of each of the single cells, using a current value obtained by measurement by the current measurement unit before the current is changed in a stepwise manner by the current supply unit and at least two of the first difference, the second difference, and the third difference; an analysis unit capable of performing multivariate analysis using distribution information of the at least two circuit constants in the plurality of single cells or distribution information of the at least two circuit constants in a plurality of normal batteries; Equipped with <6> The electronic device described in <8> The multivariate analysis method is the Mahalanobis-Taguchi method. <1> from <7> 10. An electronic device according to claim 9, wherein: <9> The multivariate analysis method used is the one-class support vector machine method. <1> from <7> 10. An electronic device according to claim 9, wherein: <10> providing a stepped current to the battery; measuring the voltage of the battery; deriving a difference between a first voltage, which is the voltage value before the current flowing through the battery is changed in a stepwise manner, and a second voltage, which is the voltage value after the current flowing through the battery is changed in a stepwise manner, based on the voltage value obtained by measurement; When deriving the difference, derive at least two of the following three differences: Contains Measurement method. a first difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed in the second voltage value; A second difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery has changed in the second voltage value. a third difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed in the second voltage value; <11> a voltage value within a period of 1 μs or more and less than 1 ms after the current is changed in a stepwise manner is used as the third voltage value, and the first difference is derived. Contains <10> The measurement method described in <12> deriving the second difference by using a voltage value within a period of 1 ms or more and less than 10 s after the current is changed in a stepwise manner as the fourth voltage value; Contains <10> The measurement method described in <13> deriving the third difference by using a voltage value within a period of 10 seconds or more and less than 10,000 seconds after the current is changed in a stepwise manner as the fifth voltage value; Contains <10> The measurement method described in <14> the battery is a single cell, The measurement method is measuring the current of the battery; calculating at least two circuit constants of an equivalent circuit of the battery using a current value obtained by measurement before the current is changed stepwise and at least two of the first difference, the second difference, and the third difference; performing a multivariate analysis using distribution information of the at least two circuit constants in a plurality of normal batteries; Contains <10> from <13> 1. The measurement method according to claim 1 , <15> the battery is a battery pack including a plurality of single cells, measuring the voltages of the plurality of cells included in the battery pack; deriving the difference for each of the unit cells; Contains <10> from <13> 1. The measurement method according to claim 1 , <16> measuring currents of the plurality of cells; calculating at least two circuit constants of an equivalent circuit of each of the single cells using a current value obtained by measurement before the current is changed in a stepwise manner and at least two of the first difference, the second difference, and the third difference; performing a multivariate analysis using distribution information of the at least two circuit constants in the plurality of single cells or distribution information of the at least two circuit constants in a plurality of normal batteries; Contains <15> The measurement method described in <17> The multivariate analysis method is the Mahalanobis-Taguchi method. <10> from <16> 1. The measurement method according to claim 1 , <18> The multivariate analysis method used is the one-class support vector machine method. <10> from <16> 1. The measurement method according to claim 1 ,

[0045] The voltage difference derivation unit 14, the circuit constant calculation unit 15, and the multivariate analysis unit 16 can be implemented by a circuit including at least one semiconductor integrated circuit, such as at least one processor (e.g., a central processing unit (CPU)), at least one application specific integrated circuit (ASIC), and / or at least one field programmable gate array (FPGA). The at least one processor can be configured to execute all or part of the various functions of the voltage difference derivation unit 14, the circuit constant calculation unit 15, and the multivariate analysis unit 16 by reading instructions from at least one non-transitory, tangible computer-readable medium. Such media can take various forms, including, but not limited to, various magnetic media such as hard disks, various optical media such as CDs or DVDs, and various semiconductor memories (i.e., semiconductor circuits) such as volatile or non-volatile memories. Volatile memories can include DRAM and SRAM. Non-volatile memories can include ROM and NVRAM. The ASIC is an integrated circuit (IC) specialized to execute all or part of the various functions of the voltage difference derivation unit 14, the circuit constant calculation unit 15, and the multivariate analysis unit 16. The FPGA is an integrated circuit designed to be configurable after manufacture so as to execute all or part of the various functions of the voltage difference derivation unit 14, the circuit constant calculation unit 15, and the multivariate analysis unit 16.

Claims

1. a current supply unit capable of supplying a current that changes stepwise to the battery; a voltage measurement unit capable of measuring the voltage of the battery; a voltage difference derivation unit that is capable of deriving a difference between a first voltage value, which is the voltage value before the current supply unit changes the current stepwise, and a second voltage value, which is the voltage value after the current supply unit changes the current stepwise, based on a voltage value obtained by measurement by the voltage measurement unit; An electronic device comprising: The voltage difference derivation unit is capable of deriving at least two of the following three differences: the battery is a single cell, The electronic device is: a current measuring unit capable of measuring the current of the battery; a calculation unit that is capable of calculating at least two circuit constants of an equivalent circuit of the battery using a current value obtained by measurement by the current measurement unit before the current is changed in a stepwise manner by the current supply unit and at least two of a first difference, a second difference, and a third difference; an analysis unit capable of performing multivariate analysis using distribution information of the at least two circuit constants for a plurality of normal batteries; Further equipped with electronic equipment. The first difference is a difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed in the second voltage value. The second difference is a difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery has changed in the second voltage value. The third difference is a difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed in the second voltage value.

2. a current supply unit capable of supplying a current that changes stepwise to the battery; a voltage measurement unit capable of measuring the voltage of the battery; a voltage difference derivation unit that is capable of deriving a difference between a first voltage value, which is the voltage value before the current supply unit changes the current stepwise, and a second voltage value, which is the voltage value after the current supply unit changes the current stepwise, based on a voltage value obtained by measurement by the voltage measurement unit; An electronic device comprising: The voltage difference derivation unit is capable of deriving at least two of the following three differences: the battery is a battery pack including a plurality of single cells, the voltage measurement unit is capable of measuring the voltages of the plurality of cells included in the battery pack, the voltage difference derivation unit is capable of deriving the difference for each of the unit cells, The electronic device is: a current measuring unit capable of measuring the current of the plurality of single cells; a calculation unit that is capable of calculating at least two circuit constants of an equivalent circuit of each of the single cells, using a current value obtained by measurement by the current measurement unit before the current is changed in a stepwise manner by the current supply unit, and at least two of a first difference, a second difference, and a third difference; an analysis unit capable of performing multivariate analysis using distribution information of the at least two circuit constants in the plurality of single cells or distribution information of the at least two circuit constants in a plurality of normal batteries; Further equipped with electronic equipment. The first difference is a difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed in the second voltage value. The second difference is a difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery has changed in the second voltage value. The third difference is a difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed in the second voltage value.

3. The multivariate analysis method is the Mahalanobis-Taguchi method.

3. The electronic device according to claim 1.

4. The multivariate analysis method is a one-class support vector machine method.

3. The electronic device according to claim 1.

5. providing a stepped current to the battery; measuring the voltage of the battery; deriving a difference between a first voltage value, which is the voltage value before the current flowing through the battery is changed in a stepwise manner, and a second voltage value, which is the voltage value after the current flowing through the battery is changed in a stepwise manner, based on the voltage value obtained by the measurement; When deriving the difference, at least two of the following three differences are derived: A measurement method comprising: the battery is a single cell, The measurement method is measuring the current of the battery; calculating at least two circuit constants of an equivalent circuit of the battery using the current value obtained by measurement before the current is changed stepwise and at least two of the first difference, the second difference, and the third difference; performing a multivariate analysis using distribution information of the at least two circuit constants for a plurality of normal batteries; Further includes Measurement method. The first difference is a difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed in the second voltage value. The second difference is a difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery has changed in the second voltage value. The third difference is a difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed in the second voltage value.

6. providing a stepped current to the battery; measuring the voltage of the battery; deriving a difference between a first voltage value, which is the voltage value before the current flowing through the battery is changed in a stepwise manner, and a second voltage value, which is the voltage value after the current flowing through the battery is changed in a stepwise manner, based on the voltage value obtained by the measurement; When deriving the difference, at least two of the following three differences are derived: A measurement method comprising: the battery is a battery pack including a plurality of single cells, The measurement method is measuring the voltages of the plurality of cells included in the battery pack; deriving the difference for each of the unit cells; measuring currents of the plurality of cells; calculating at least two circuit constants of an equivalent circuit of each of the single cells using a current value obtained by measurement before the current is changed in a stepwise manner and at least two of the first difference, the second difference, and the third difference; performing a multivariate analysis using distribution information of the at least two circuit constants in the plurality of single cells or distribution information of the at least two circuit constants in a plurality of normal batteries; Further includes Measurement method. The first difference is a difference between the first voltage value and a third voltage value, which is a voltage value after a component derived from the bulk resistance of the battery has changed in the second voltage value. The second difference is a difference between the first voltage value and a fourth voltage value, which is a voltage value after a component derived from the charge transfer resistance of the battery has changed in the second voltage value. The third difference is a difference between the first voltage value and a fifth voltage value, which is a voltage value after a component derived from the diffusion resistance of the battery has changed in the second voltage value.

7. The multivariate analysis method is the Mahalanobis-Taguchi method. The measurement method according to claim 5 or 6.

8. The multivariate analysis method is a one-class support vector machine method. The measurement method according to claim 5 or 6.

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