Internal resistance calculation data acquisition method and internal resistance measurement method

Abstract

To shorten the time required for data acquisition when current-voltage measurement is repeated to acquire data for SOC adjustment and internal resistance calculation.SOLUTION: An internal resistance calculation data acquisition method according to an embodiment is an internal resistance calculation data acquisition method executed by a measurement data acquisition device that repeatedly performs an SOC adjustment step of adjusting a secondary battery to be measured to a predetermined SOC and a current-voltage measurement step of discharging or charging the secondary battery adjusted to the predetermined SOC and measuring a current and a voltage in the secondary battery to acquire internal resistance measurement data of the secondary battery. After the end of the current-voltage measurement step, the process proceeds to the SOC adjustment step without waiting for the elapse of the polarization relaxation time for relaxing the polarization generated in the secondary battery by the execution of the current-voltage measurement step.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a method for acquiring data for calculating internal resistance and a method for measuring internal resistance. [Background technology]

[0002] Conventionally, the IV measurement method is known as a method for testing the internal resistance of lithium-ion batteries. In the IV method, for example, the current and voltage are measured when a lithium ion battery is discharged or charged, and the resistance value is calculated from the slope of an approximate line obtained by plotting the current on the horizontal axis and the voltage at that time on the vertical axis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-131874 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional IV measurement method described above, the lithium-ion battery whose internal resistance is to be measured is charged or discharged until its SOC (State Of Charge) reaches a predetermined state, and then the internal resistance is measured after a predetermined rest time (polarization relaxation rest time) has elapsed since the SOC adjustment in order to eliminate polarization inside the lithium-ion battery caused by the charging or discharging. Furthermore, in conventional SOC adjustment using constant current control, it is necessary to measure the voltage, and in order to measure the voltage accurately, a configuration has been adopted in which a predetermined rest period is inserted after charging or discharging for measuring the internal resistance.

[0005] The object of the present invention is to provide a method for obtaining data for calculating internal resistance and a method for measuring internal resistance, which can obtain data for calculating internal resistance by providing a rest period before and after SOC adjustment when repeatedly performing current-voltage measurements to adjust the SOC and obtain data for calculating internal resistance, thereby shortening the time required for evaluating the characteristics of a secondary battery. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the method for acquiring data for calculating internal resistance according to the embodiment is a method for acquiring data for calculating internal resistance that is executed by a measurement data acquisition device that repeatedly performs an SOC adjustment step of adjusting a secondary battery to be measured to a predetermined SOC, and a current-voltage measurement step of discharging or charging the secondary battery adjusted to the predetermined SOC and measuring the current and voltage in the secondary battery, and acquires the data as data for measuring the internal resistance of the secondary battery. In the SOC adjustment step, the SOC is adjusted by passing a current equivalent to the amount of current obtained by accumulating the current that flows through the secondary battery due to discharging or charging in the current-voltage measurement, and after the current-voltage measurement step is completed, the method transitions to the SOC adjustment step without waiting for the elapse of the polarization relaxation time that relaxes the polarization that occurs in the secondary battery due to the execution of the current-voltage measurement step.

[0007] In addition, the internal resistance measurement method of the embodiment includes a resistance calculation step of calculating the internal resistance value of the secondary battery based on multiple sets of current-voltage measurement results obtained as data for measuring the internal resistance of the secondary battery by executing the above-mentioned method for obtaining data for calculating internal resistance. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce the influence of polarization of a secondary battery caused by performing current-voltage measurements to charge or discharge the secondary battery, while shortening the time required to move on to SOC adjustment after current-voltage measurements, and ultimately significantly shortening the time required to evaluate the characteristics of the secondary battery. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a schematic diagram of an internal resistance measuring system according to an embodiment. [Figure 2] FIG. 2 is a functional block diagram of the internal resistance measuring device. [Figure 3] FIG. 3 is an explanatory diagram of the problems of the conventional art and the effects of the embodiment. [Figure 4] FIG. 4 is a diagram illustrating the outline of the operation of the embodiment. [Figure 5] FIG. 5 is a processing flowchart of the embodiment. [Figure 6] FIG. 6 is an explanatory diagram of the calculation of the internal resistance. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram of an internal resistance measuring system according to an embodiment. As shown in FIG. 1, the internal resistance measuring system 10 of the embodiment includes a controller 11, a current-voltage measuring device 12, and a thermostatic chamber 13. Here, the controller 11 functions as a resistance calculation device that executes a resistance calculation step, and the current-voltage measurement device 12 functions as a measurement data acquisition device.

[0011] The controller 11 controls the entire internal resistance measuring system 10 . Specifically, the controller 11 outputs a charge / discharge control signal CMC to set the charge / discharge conditions, i.e., the SOC set value and the charge / discharge current set value, and outputs a temperature condition control signal CTM to set the temperature inside the thermostatic chamber 13 when measuring the internal resistance, i.e., the temperature of the secondary battery BAT to be measured.

[0012] Furthermore, the controller 11 calculates the internal resistance value of the secondary battery BAT based on multiple sets of current-voltage measurement results obtained as data for measuring the internal resistance of the secondary battery BAT acquired by a current-voltage measurement device 12 as a measurement data acquisition device. Furthermore, the controller 11 may be designed as a dedicated controller, or a general-purpose personal computer or the like may be used.

[0013] Based on the charge / discharge control signal CMC output by the controller 11, the current-voltage measuring device 12 charges / discharges the secondary battery BAT to be measured using the four-terminal method, simultaneously detects the charge / discharge current and the charge / discharge voltage, and outputs current detection data and voltage detection data as the current-voltage measurement results, as will be described later. The thermostatic chamber 13 performs control so as to maintain the internal temperature at a temperature corresponding to the temperature condition control signal CTM output by the controller 11.

[0014] FIG. 2 is a functional block diagram of the internal resistance measurement system. The controller 11 functions as a charge / discharge control unit 21, a charge / discharge power amount detection unit 22, a data storage unit 23, an internal resistance value calculation unit 24, and a temperature control unit 25. The current-voltage measuring device 12 functions as a charge / discharge unit 31, a current measuring unit 32, and a voltage measuring unit 33.

[0015] The charge / discharge control unit 21 of the controller 11 outputs a charge / discharge control signal CMC to the charge / discharge unit 31 of the current / voltage measuring device 12 in order to control the charging and discharging of the secondary battery BAT during current / voltage measurement or SOC adjustment according to a predetermined processing procedure. The charge / discharge control unit 21 also functions as an SOC adjustment unit.

[0016] The charge / discharge power amount detection unit 22 of the controller 11 calculates the amount of power based on the current value corresponding to the current detection data DI and the voltage value corresponding to the voltage detection data DV output by the current-voltage measuring device 12, and accumulates the calculated amount of power to calculate the amount of charging power during charging and the amount of discharging power during discharging. Specifically, the amount of charge or discharge power associated with current-voltage measurement or the amount of charge or discharge power associated with SOC adjustment is calculated.

[0017] The data storage unit 23 of the controller 11 stores the current detection data DI and voltage detection data DV output by the current-voltage measuring device 12 in association with each other, and further in association with the temperature corresponding to the temperature condition control signal CTM.

[0018] The internal resistance value calculation unit 24 of the controller 11 obtains a current-voltage approximation line based on multiple sets of current detection data DI and voltage detection data DV corresponding to the temperature and SOC state in the thermostatic chamber 13, and calculates the slope of the line as the internal resistance value.

[0019] The temperature control unit 25 of the controller 11 outputs a temperature condition control signal CTM to the thermostatic chamber 13 to set the internal temperature of the thermostatic chamber 13 .

[0020] On the other hand, the charge / discharge unit 31 of the current / voltage measuring device 12 charges / discharges the secondary battery BAT based on the charge / discharge control signal CMC, and performs current / voltage measurement or SOC adjustment. The current measurement unit 32 of the current-voltage measurement device 12 detects the charging or discharging current of the secondary battery BAT and outputs it as current detection data DI to the charging / discharging power amount detection unit 22 and data storage unit 23 of the controller 11.

[0021] The voltage measurement unit 33 detects the charging voltage of the secondary battery BAT when measuring the internal resistance or the discharging voltage when measuring the internal resistance, and outputs it as voltage detection data DV to the charge / discharge energy detection unit 22 and data memory unit 23 of the controller 11.

[0022] Here, the characteristics evaluation test of the secondary battery will be described. In the battery characteristic evaluation test, the internal resistance is measured at multiple temperatures and multiple SOCs.

[0023] When measuring internal resistance, the temperature and SOC are kept the same, and the voltage value is measured while changing the current value, and the current-voltage approximation line (IV approximation line) is obtained. The internal resistance value at each temperature and SOC is calculated by determining the slope of this approximation line. As a result, data can be obtained to evaluate the characteristics of secondary batteries under various usage environments.

[0024] Before describing the embodiments in detail, the problems of the prior art will be explained. FIG. 3 is an explanatory diagram of the problems of the conventional art and the effects of the embodiment. In the above characteristic evaluation test, in order to measure the internal resistance, it is necessary to charge or discharge the secondary battery BAT, and polarization occurs due to the current flowing through the secondary battery BAT. Conventionally, constant current charging or constant current discharging has been performed to adjust the SOC. For this reason, as shown in Figure 3(A), it is not possible to accurately measure the voltage of the secondary battery BAT when polarization occurs in the secondary battery BAT, and a first rest time (first polarization relaxation time) is set after the internal resistance measurement process. Similarly, during SOC adjustment, the secondary battery BAT needs to be charged or discharged, and polarization occurs due to the current flowing through the secondary battery BAT. Therefore, in order to measure the current and voltage accurately, the second polarization relaxation time was provided even after the SOC adjustment process.

[0025] More specifically, in the past, it took 52 days, including rest time, to perform all internal resistance measurements on one secondary battery BAT, of which the time required for current-voltage measurement (IV measurement) was 5 hours, the time required for temperature adjustment was 240 hours (= 10 days), the time required for SOC adjustment was 288 hours (= 12 days), and the time required for rest time was 720 hours (= 30 days).

[0026] As mentioned above, the time required for the rest time accounts for more than half of the internal resistance measurement time. By reducing this rest time, as shown in Figure 3(B), it can be seen that the internal resistance measurement time can be significantly reduced.

[0027] Next, the operation of the embodiment will be described. FIG. 4 is a diagram illustrating the outline of the operation of the embodiment. In this case, as an example, the values ​​of temperature, SOC, and charging or discharging current when measuring the internal resistance are four values ​​of temperature (first temperature value to fourth temperature value) in the temperature adjustment step ST1, nine values ​​of SOC (first SOC value to ninth SOC value) in the SOC adjustment step ST2, and eight values ​​of current (first current value to eighth current value) in the internal resistance measurement step ST3. If we were to carry out these steps simply, we would need to perform 4 x 9 x 8 = 288 IV measurements. However, in reality, there are value combinations that can be omitted without affecting the internal resistance measurement results, so we have found that data accuracy can be ensured by performing approximately 140 pre-selected IV measurements.

[0028] FIG. 5 is a processing flowchart of the embodiment. First, the controller 11 functions as the temperature control unit 25 and outputs a temperature condition control signal CTM to the thermostatic chamber 13 in order to adjust the temperature inside the thermostatic chamber 13 to the first temperature (step S11). Next, the controller 11 functions as a charge / discharge control unit 21 and outputs a charge / discharge control signal CMC to the charge / discharge unit 31 of the current-voltage measuring device 12 so that the SOC of the secondary battery BAT becomes a predetermined SOC value (in this case, the first SOC value since this is the first time).

[0029] As a result, the current-voltage measuring device 12 performs charging or discharging to adjust the SOC of the secondary battery BAT to a predetermined SOC value (step S12).

[0030] In this case, the current measurement unit 32 of the current-voltage measurement unit 12 of the current-voltage measurement device 12 detects the charging current or discharging current of the secondary battery BAT associated with the SOC adjustment, and outputs it as current detection data DI to the charging / discharging power amount detection unit 22 and data memory unit 23 of the controller 11.

[0031] In addition, the voltage measurement unit 33 of the current-voltage measurement device 12 detects the charging voltage or discharging voltage of the secondary battery BAT associated with SOC adjustment, and outputs the detected voltage data DV to the charging / discharging power amount detection unit 22 and data memory unit 23 of the controller 11.

[0032] As a result, the charge / discharge power amount detection unit 22 of the controller 11 calculates the amount of charge or discharge power required for SOC adjustment based on the current corresponding to the input current detection data DI and the voltage corresponding to the input voltage detection data DV.

[0033] When the SOC is adjusted, a charging current or discharging current flows through the secondary battery BAT due to the SOC adjustment, causing polarization.

[0034] Therefore, the controller 11 determines whether or not a predetermined rest time (polarization relaxation time) has elapsed, during which the influence of polarization can be ignored in the internal resistance measurement process (step S13). In this case, the predetermined rest time is calculated and set by conducting a test in advance using a secondary battery BAT of the same specifications.

[0035] In the determination at step S13, if the predetermined rest time has not yet elapsed (step S13; No), the controller 11 goes into a standby state.

[0036] If it is determined in step S13 that the predetermined rest time has elapsed (step S13; Yes), current-voltage measuring device 12 performs current-voltage measurement (step S14).

[0037] In this state, the effect of polarization due to SOC adjustment on current-voltage measurement is negligible, so the current-voltage measuring device 12 functions as a current measuring unit 32, detects the charging current or discharging current of the secondary battery BAT, and outputs the detected current data DI to the charging / discharging power amount detecting unit 22 and data memory unit 23 of the controller 11.

[0038] In addition, the current-voltage measuring device 12 functions as a voltage measuring unit 33, detects the charging voltage of the secondary battery BAT during current-voltage measurement or the discharging voltage during current-voltage measurement, and outputs it as voltage detection data DV to the charge / discharge power amount detection unit 22 and data memory unit 23 of the controller 11.

[0039] As a result, the data storage unit 23 of the controller 11 stores the input current detection data DI, voltage detection data DV, and temperature (temperature at the time of measurement) corresponding to the temperature control signal CTM in association with one another.

[0040] Then, the controller 11 determines whether or not measurements (acquisition of corresponding current detection data DI and voltage detection data DV) for all current values ​​(in the above example, the first to eighth current values) have been completed (step S15).

[0041] In the judgment of step S15, if the acquisition of the current detection data DI and voltage detection data DV corresponding to all current values ​​at the set temperature and set SOC at that time point has not yet been completed (step S15; No), the charge / discharge control unit 21 of the controller 11 changes the current value (step S16) and performs current-voltage measurement again at the changed current value (step S14).

[0042] In the judgment of step S15, if the acquisition of current detection data DI and voltage detection data DV corresponding to all current values ​​at the set temperature and set SOC at that time has been completed (step S15; Yes), the controller 11 functions as the internal resistance value calculation unit 24, reads the acquired current detection data DI, voltage detection data DV and corresponding temperatures from the data memory unit 23, calculates an IV approximation line, and calculates the slope of the calculated IV approximation line as the internal resistance value (step S17).

[0043] FIG. 6 is an explanatory diagram of the calculation of the internal resistance. FIG. 6 shows an example of calculation of the internal resistance when the measurement temperatures are 25°C and -10°C. In FIG. 6, the approximation curve L1 corresponds to the IV measurement data corresponding to the first to eighth current values ​​at a temperature of 25°C at a certain SOC value, and the internal resistance value corresponding to the slope (=V / I) was 4.2 mΩ.

[0044] In addition, approximate curve L2 corresponds to the current-voltage measurement data corresponding to the first current value to the eighth current value at a temperature of -10°C at the same SOC value as approximate curve L1, and the internal resistance value corresponding to the slope (V / I) was 0.9 mΩ.

[0045] The internal resistance value calculated in this manner is displayed on a display device (not shown) of the controller 11, or is output from the controller 11 to an external device (such as a higher-level controller or a printer) as internal resistance measurement data, and is then used.

[0046] Next, the controller 11 determines whether or not measurements (acquisition of corresponding detected current data DI and detected voltage data DV) for all SOC values ​​(in the above example, the first to ninth SOC values) have been completed (step S18).

[0047] In the judgment of step S18, if the acquisition of current detection data DI and voltage detection data DV corresponding to all SOC values ​​at the set temperature at that time has not yet been completed (step S18; No), the charge / discharge control unit 21 of the controller 11 changes the SOC value of the secondary battery BAT via the charge / discharge unit 31 of the current-voltage measuring device 12 (step S19), and the processing proceeds to step S12.

[0048] In this case, the difference between the SOC value immediately before the change and the SOC value after the change can be grasped as the amount of power, so based on the detection result of the charge / discharge power detection unit 22 of the controller 11, the magic power control unit 21 calculates the amount of power required for the change as the amount of charging current or discharging current, and charges or discharges the secondary battery BAT, thereby adjusting the SOC only by controlling the amount of current (amount of charging current or amount of discharging current) without measuring the voltage of the secondary battery BAT (step S12).

[0049] Therefore, in the SOC adjustment, there is no need to measure voltage and there is no influence of polarization, so it is possible to move on to the SOC adjustment without waiting for the lapse of a rest time (polarization relaxation time) as in the conventional method, or more preferably, without any rest time at all, as shown in Figure 3(B), and to move on to the SOC adjustment immediately after the end of the internal resistance measurement step, thereby significantly shortening the internal resistance measurement time.

[0050] As described above, the time required for the rest time accounts for more than half of the internal resistance measurement time, and by reducing this time, it can be seen that according to this embodiment, it is possible to significantly reduce the internal resistance measurement time.

[0051] In this case, if the SOC adjustment is started without waiting for a sufficient polarization relaxation time to elapse, as in the case where the rest time after current-voltage measurement by the current-voltage measuring device 12 is completely eliminated, the internal temperature of the secondary battery BAT will rise during the SOC adjustment, and thermal energy will be used as chemical energy (or kinetic energy), which will speed up the movement of ions inside the secondary battery BAT. As a result, the time required for polarization relaxation, i.e., the rest time after SOC adjustment and before resistance measurement, can also be shortened compared to the conventional case.

[0052] This internal temperature rise will decrease to a predetermined temperature during the rest period before the next current-voltage measurement after the SOC adjustment, and will not affect the current-voltage measurement or the internal resistance measurement.

[0053] On the other hand, if it is determined in step S18 that the acquisition of the current detection data DI and the voltage detection data DV corresponding to all SOC values ​​at the set temperature at that time has been completed (step S18; Yes), the controller 11 determines whether or not the measurement (acquisition of the corresponding current detection data DI and voltage detection data DV) at all temperature values ​​(in the above example, the first temperature value to the fourth temperature value) has been completed (step S20).

[0054] In the judgment of step S20, if the acquisition of the current detection data DI and voltage detection data DV corresponding to all temperature values ​​has not yet been completed (step S20; No), the temperature control unit 25 of the controller 11 changes the temperature value inside the thermostatic chamber 13 using the temperature control signal CTM (step S21), and the controller 11 then transitions the processing to step S11 and repeats the above-mentioned processing.

[0055] In the judgment of step S20, if it is determined that the acquisition of the current detection data DI and the voltage detection data DV corresponding to all temperature values ​​has been completed (step S20; Yes), the controller 11 ends the process since all internal resistance measurement processes have been completed.

[0056] As described above, according to the embodiment, the SOC adjustment after the internal resistance measurement process is performed by power energy integration control, so there is no need to accurately determine the voltage of the secondary battery BAT during SOC adjustment. Therefore, it is possible to move on to SOC adjustment without waiting for the lapse of a rest time (polarization relaxation time) after charging or discharging for internal resistance measurement as in the conventional case, and the internal resistance measurement time can be shortened.

[0057] More preferably, the SOC adjustment can be started immediately after the internal resistance measurement step is completed without providing any rest time, thereby significantly shortening the internal resistance measurement time. Furthermore, if the rest time after measuring the internal resistance is eliminated or eliminated to a certain extent, the internal temperature of the secondary battery BAT will rise during the SOC adjustment, which will speed up the movement of ions inside the secondary battery BAT and shorten the time required for polarization relaxation.

[0058] Therefore, the rest time after SOC adjustment and before resistance measurement (corresponding to the conventional second rest time) can also be shortened compared to the conventional method, thereby further reducing the time required for internal resistance measurement.

[0059] Although the embodiments of the present invention have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, this embodiment is included within the scope and spirit of the invention, and is also included in the inventions and their equivalents described in the claims.

[0060] [Note] Preferred embodiments of the present invention will be described below. [First aspect] an SOC adjustment step of adjusting the secondary battery to a predetermined SOC; a current-voltage measurement step of discharging or charging the secondary battery adjusted to the predetermined SOC and measuring the current and voltage in the secondary battery; and acquiring data for measuring the internal resistance of the secondary battery. the SOC adjusting step adjusts the SOC by flowing a current corresponding to a current amount obtained by integrating currents flowing through the secondary battery due to the discharging or charging in the current-voltage measurement; After the current-voltage measurement step is completed, the process proceeds to the SOC adjustment step without waiting for a polarization relaxation time for relaxing the polarization generated in the secondary battery by the current-voltage measurement step. This is a method for obtaining data for calculating internal resistance. According to this aspect, when current-voltage measurements are repeatedly performed to adjust the SOC and obtain data for calculating the internal resistance, by providing a rest period before and after the SOC adjustment, the time required to obtain data for calculating the internal resistance, and therefore the time required to evaluate the characteristics of the secondary battery, can be shortened. [Second mode] A first aspect of the method for acquiring data for calculating internal resistance includes a temperature adjustment step of adjusting a temperature of the secondary battery to a predetermined temperature, The method for acquiring data for calculating internal resistance includes repeatedly performing the SOC adjustment step and the current-voltage measurement step at a plurality of different adjustment temperatures to acquire data for measuring the internal resistance of the secondary battery. According to this aspect, when acquiring data for calculating internal resistance at multiple temperatures, by repeatedly performing current-voltage measurements, a rest period can be provided before and after SOC adjustment to acquire data, thereby shortening the time required for evaluating the characteristics of the secondary battery. [Third aspect] This is an internal resistance measurement method executed by an internal resistance measurement device that executes the internal resistance calculation data acquisition method of the first or second aspect, and includes a resistance calculation step that calculates the internal resistance value of the secondary battery based on multiple sets of current-voltage measurement results obtained as internal resistance measurement data of the secondary battery. According to this aspect, when current-voltage measurements required for measuring internal resistance are repeatedly performed, a rest period is provided before and after SOC adjustment, thereby shortening the time required for data acquisition and ultimately for measuring internal resistance. [Fourth aspect] The third aspect of the internal resistance measuring method further includes, after completion of the SOC adjustment step, a pause step of waiting for a predetermined polarization relaxation pause time to elapse for relaxing polarization generated in the secondary battery by executing the SOC adjustment step. According to this embodiment, a pause step is not provided after the current-voltage measurement step but before the SOC adjustment, and a pause step is provided after the SOC adjustment step. Therefore, at the stage of transitioning to SOC adjustment, the secondary battery is in a temperature-raised state due to the execution of the current-voltage measurement step, which facilitates the movement of ions within the secondary battery and allows the pause step itself to be set to a short length. [Fifth mode] In the third aspect of the internal resistance measurement method, the resistance calculation step calculates, as the internal resistance value of the secondary battery, the slope of a current-voltage change approximation line corresponding to the internal resistance measurement data obtained by measuring the voltage of the secondary battery multiple times while changing the current value for discharging or charging for one SOC value. According to this aspect, the internal resistance value of the secondary battery can be calculated easily and accurately. [Sixth aspect] A measurement data acquisition device that acquires data for measuring the internal resistance of a secondary battery by repeatedly performing a process of adjusting a secondary battery to a predetermined SOC, and a current-voltage measurement process of discharging or charging the secondary battery adjusted to the predetermined SOC and measuring the current and voltage of the secondary battery, an SOC adjustment unit that adjusts the SOC by supplying a current corresponding to an amount of current obtained by integrating currents that have flowed through the secondary battery due to the discharging or charging in the current-voltage measurement process; a current-voltage measurement unit that discharges or charges the secondary battery adjusted to the predetermined SOC and measures the current and voltage in the secondary battery, The SOC adjustment unit is a measurement data acquisition device that adjusts the SOC after the current-voltage measurement process is completed without waiting for the elapse of a polarization relaxation time that relieves the polarization caused in the secondary battery by executing the current-voltage measurement process. According to this aspect, when current-voltage measurements are repeatedly performed to adjust the SOC and obtain data for calculating the internal resistance, by providing a rest period before and after the SOC adjustment, the time required to obtain data for calculating the internal resistance, and therefore the time required to evaluate the characteristics of the secondary battery, can be shortened. [Seventh aspect] A sixth aspect of the measurement data acquisition device includes a temperature adjustment step of adjusting the temperature of the secondary battery to a predetermined temperature, The measurement data acquisition device repeatedly performs the SOC adjustment step and the current-voltage measurement step at a plurality of different adjustment temperatures to acquire data for measuring the internal resistance of the secondary battery. According to this aspect, when acquiring data for calculating internal resistance at multiple temperatures, by repeatedly performing current-voltage measurements, a rest period can be provided before and after SOC adjustment to acquire data, thereby shortening the time required for evaluating the characteristics of the secondary battery. [Eighth aspect] A measurement data acquisition device according to the sixth or seventh aspect; and a resistance calculation device that calculates the internal resistance value of the secondary battery based on multiple sets of current-voltage measurement results obtained as internal resistance measurement data of the secondary battery acquired by the measurement data acquisition device. According to this aspect, it is possible to reduce the influence of polarization of the secondary battery due to the execution of the SOC adjusting step, while ensuring sufficient measurement accuracy, and to accurately calculate the internal resistance value of the secondary battery. [Ninth aspect] In an eighth aspect of the internal resistance measurement system, the measurement data acquisition device is an internal resistance measurement system that includes, after completion of the SOC adjustment step, a pause step of waiting for the passage of a predetermined polarization relaxation pause time that relaxes the polarization caused in the secondary battery by executing the SOC adjustment step. According to this embodiment, a pause step is not provided after the current-voltage measurement step but before the SOC adjustment, and a pause step is provided after the SOC adjustment step. Therefore, at the stage of transitioning to SOC adjustment, the secondary battery is in a temperature-raised state due to the execution of the current-voltage measurement step, which facilitates the movement of ions within the secondary battery and allows the pause step itself to be set to a short length. [Tenth aspect] In the internal resistance measurement system of the eighth aspect, the resistance calculation device calculates the internal resistance value of the secondary battery as the slope of a current-voltage change approximation line corresponding to the internal resistance measurement data obtained by measuring the voltage of the secondary battery multiple times while changing the current value for discharging or charging for one SOC value. According to this aspect, it is possible to reduce the influence of polarization of the secondary battery due to the execution of the SOC adjusting step, while ensuring sufficient measurement accuracy, and to accurately calculate the internal resistance value of the secondary battery. [Explanation of symbols]

[0061] 10 Internal Resistance Measurement System 11 Controller 12 Current-voltage measuring device 13 Temperature bath 21 Charge / discharge control unit 22 Charging and discharging power amount detection unit 23 Data storage unit 24 Internal resistance calculation section 26 Temperature control unit 31 Charge / discharge section 32 Current measurement section 33 Voltage measurement section BAT secondary battery CMC internal resistance measurement condition control signal CTM Temperature condition control signal DI Current detection data DV voltage detection data L1, L2 approximate curve

Claims

1. an SOC adjusting step of adjusting the secondary battery to be measured to a predetermined SOC; a current-voltage measurement step of discharging or charging the secondary battery adjusted to the predetermined SOC and measuring the current and voltage in the secondary battery; and acquiring data for calculating the internal resistance of the secondary battery as data for measuring the internal resistance of the secondary battery. the SOC adjusting step adjusts the SOC by flowing a current corresponding to a current amount obtained by integrating currents flowing through the secondary battery due to the discharging or the charging in the current-voltage measuring step; After the current-voltage measurement step is completed, the process proceeds to the SOC adjustment step without waiting for a polarization relaxation time for relaxing the polarization generated in the secondary battery by the execution of the current-voltage measurement step to elapse. How to obtain data for calculating internal resistance.

2. a temperature adjusting step of adjusting the temperature of the secondary battery to a predetermined temperature; The SOC adjustment step and the current-voltage measurement step are repeatedly performed at a plurality of different adjustment temperatures to obtain data for measuring the internal resistance of the secondary battery. The method for obtaining data for calculating internal resistance according to claim 1 .

3. 3. An internal resistance measurement method executed by an internal resistance measurement device that executes the method for acquiring data for calculating internal resistance according to claim 1 or 2, a resistance calculation step of calculating an internal resistance value of the secondary battery based on a plurality of sets of current-voltage measurement results obtained as internal resistance measurement data of the secondary battery; Internal resistance measurement method.

4. a pause step of waiting for a predetermined polarization relaxation pause time to elapse after the SOC adjustment step is completed, for relaxing polarization generated in the secondary battery by the execution of the SOC adjustment step; The internal resistance measuring method according to claim 3 .

5. the resistance calculation step calculates, as the internal resistance value of the secondary battery, a slope of a current-voltage change approximation line corresponding to the internal resistance measurement data obtained by measuring the voltage of the secondary battery multiple times while changing the current value for discharging or charging for one SOC value; The internal resistance measuring method according to claim 3 .

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