Power supply system, battery pack, and abnormality determination method of battery cell

Abstract

To provide a technique capable of appropriately handling a battery cell when the thermal stability of the battery cell is deteriorated.SOLUTION: A power supply system includes a determination power source generator, a first measurement part, and a determination part. The determination power source generator applies a first signal including a first component having a first frequency and a second component having a second frequency to a battery cell. The first measurement part measures a first current value and a first voltage value corresponding to the first component and a second current value and a second voltage value corresponding to the second component. The determination part calculates a first impedance based on the first current value and the first voltage value, calculates a second impedance based on the second current value and the second voltage value, and determines that the battery cell is abnormal based on the first impedance and the second impedance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to techniques for determining when the thermal stability of a battery cell is degraded. [Background technology]

[0002] The battery pack described in Patent Document 1 calculates the DC resistance component and the polarization resistance component of the secondary battery, and calculates the degree of capacity degradation relative to the fully charged capacity at the time of shipment from the factory based on the DC resistance component and the polarization resistance component. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-103291 A Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the usage environment, the capacity of the battery cell may deteriorate without the thermal stability of the battery cell being deteriorated, or the capacity may deteriorate while the thermal stability of the battery cell is being deteriorated. If the thermal stability of the battery cell is deteriorated, problems may occur in the battery cell if the battery cell is continued to be used. The above-mentioned battery pack cannot determine whether the thermal stability of the battery cell is deteriorated, and therefore cannot properly handle the battery cell when the thermal stability of the battery cell is deteriorated.

[0005] One aspect of the present disclosure provides a technique that allows appropriate handling of a battery cell when the thermal stability of the battery cell is reduced. [Means for solving the problem]

[0006] A power supply system according to one aspect of the present disclosure includes a battery pack including a battery cell, and a power supply unit configured to be connected to the battery pack. The battery pack or the power supply unit includes a determination power supply generating section, a first measuring section, and a determining section. The determination power supply generating section applies a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency to the battery cell. The first measuring section measures a first current value flowing into the battery cell and a first voltage value of the battery cell corresponding to the application of the first component to the battery cell, and a second current value flowing into the battery cell and a second voltage value of the battery cell corresponding to the application of the second component to the battery cell. The determining section calculates a first impedance based on the first current value and the first voltage value measured by the first measuring section, calculates a second impedance based on the second current value and the second voltage value measured by the first measuring section, and determines that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance.

[0007] A power supply system according to one aspect of the present disclosure can calculate the impedance of the positive electrode and the impedance of the negative electrode of a battery cell by applying a signal including two different frequency components to the battery cell. A battery cell tends to have high thermal stability when the impedance of the positive electrode is large. A battery cell tends to have low thermal stability when the impedance of the negative electrode is large, and high thermal stability when the impedance of the negative electrode is small. Therefore, the range of values ​​that the impedance of the positive electrode and the negative electrode can take when the capacity deterioration with a decrease in thermal stability occurs in the battery cell is different from the range of values ​​that the impedance of the positive electrode and the negative electrode can take when the capacity deterioration without a decrease in thermal stability occurs in the battery cell. Therefore, the power supply system can determine that the battery cell is in an abnormal state with a decrease in thermal stability based on the first impedance and the second impedance. In addition, when the thermal stability of the battery cell is decreased, the battery cell can be appropriately handled.

[0008] A method for determining an abnormality in a battery cell according to another aspect of the present disclosure includes applying to a battery cell a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency, measuring a first current value flowing into the battery cell and a first voltage value of the battery cell corresponding to the application of the first component to the battery cell, and a second current value flowing into the battery cell and a second voltage value of the battery cell corresponding to the application of the second component to the battery cell, calculating a first impedance based on the first current value and the first voltage value, calculating a second impedance based on the second current value and the second voltage value, and determining that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance.

[0009] According to the above method, the same effects as those of the above power supply system are achieved.

[0010] A battery pack according to another aspect of the present disclosure includes a battery cell, a power source for determination generation unit, a measurement unit, and a determination unit. The power source for determination generation unit applies a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency to the battery cell. The measurement unit measures a first current value flowing into the battery cell and a first voltage value of the battery cell corresponding to the application of the first component to the battery cell, and a second current value flowing into the battery cell and a second voltage value of the battery cell corresponding to the application of the second component to the battery cell. The determination unit calculates a first impedance based on the first current value and the first voltage value measured by the measurement unit, calculates a second impedance based on the second current value and the second voltage value measured by the measurement unit, and determines that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance.

[0011] The battery pack provides the same effects as the power supply system.

[0012] A battery pack according to another aspect of the present disclosure includes a battery cell, a current measurement unit, a voltage measurement unit, and a control unit. The current measurement unit measures and outputs a value of a current flowing from the battery cell. The voltage measurement unit measures and outputs a voltage value of the battery cell. The control unit calculates a deterioration parameter of a positive electrode of the battery cell and a deterioration parameter of a negative electrode of the battery cell based on the input current value and voltage value, and performs charge / discharge control of the battery cell based on the calculated deterioration parameter of the positive electrode and the deterioration parameter of the negative electrode.

[0013] The battery pack calculates the deterioration parameters of each of the positive and negative electrodes of the battery cell. The battery cell tends to have high thermal stability when the positive electrode is deteriorated. The battery cell tends to have low thermal stability when the negative electrode is deteriorated, and high thermal stability when the negative electrode is not deteriorated. Therefore, the range of values ​​that the two deterioration parameters can take when the thermal stability of the battery cell is reduced is different from the range of values ​​that the two deterioration parameters can take when the thermal stability of the battery cell is not reduced. The battery pack performs charging control of the battery cell based on the two deterioration parameters, so that the battery cell can be appropriately handled when the thermal stability of the battery cell is reduced. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing the configuration of a battery pack and a charger according to a first embodiment. [Diagram 2] 4 is a flowchart showing a charging control process executed by the battery pack and the charger according to the first embodiment. [Diagram 3] FIG. 4 is a diagram showing an example of the relationship between the positive electrode resistance value and the negative electrode resistance value and the presence or absence of a decrease in thermal stability according to the first embodiment. [Figure 4] 5 is a flowchart showing an abnormality determination process executed by a battery pack and a charger according to a first example of the first embodiment. [Figure 5A] 5 is a diagram showing waveforms of signals applied to a battery cell according to the first embodiment. FIG. [Figure 5B] 5 is a diagram showing a method for calculating a positive electrode resistance value and a negative electrode resistance value of a battery cell according to a first example of the first embodiment. FIG. [Figure 6] 10 is a flowchart showing an abnormality determination process executed by a battery pack and a charger according to a second example of the first embodiment. [Figure 7] 13 is a diagram showing a method for calculating a positive electrode resistance value and a negative electrode resistance value of a battery cell according to a second example of the first embodiment. FIG. [Figure 8] 5 is a diagram showing a discharge control process executed by the battery pack according to the first embodiment. FIG. [Figure 9] FIG. 11 is a diagram showing the configuration of a battery pack and a charger according to a second embodiment. [Figure 10] 10 is a flowchart showing a first example of an abnormality determination process executed by a battery pack and a charger according to a second embodiment. [Figure 11] 13A and 13B are diagrams illustrating a first example of a method for calculating the waveform of a signal applied to a battery cell according to a second embodiment and a positive electrode resistance value and a negative electrode resistance value. [Figure 12] 10 is a flowchart showing a second example of an abnormality determination process executed by a battery pack and a charger according to a second embodiment. [Figure 13] 13A and 13B are diagrams illustrating a second example of a method for estimating the waveform of a signal applied to a battery cell according to a second embodiment and the positive electrode impedance and the negative electrode impedance. [Figure 14] FIG. 11 is a diagram showing the configuration of a battery pack and a charger according to a third embodiment. [Figure 15] 13 is a flowchart showing an abnormality determination process executed by a battery pack and a charger according to a third embodiment. [Figure 16] 13A to 13C are diagrams showing a method for estimating the waveform of a signal applied to a battery cell according to a third embodiment and the positive electrode impedance and the negative electrode impedance. [Figure 17] FIG. 13 is a diagram showing a charging control process executed by a battery pack and a charger according to a fourth embodiment. [Figure 18]FIG. 13 is a diagram showing a charging control process executed by a battery pack and a charger according to a fifth embodiment. [Figure 19] FIG. 13 is a diagram showing the configuration of a battery pack and a charger according to a sixth embodiment. [Figure 20] FIG. 13 is a diagram showing the configuration of a battery pack and a charger according to a seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (Summary of the embodiment) In one embodiment, a power supply system having at least one of the following features 1 to 5 may be provided. Feature 1: Battery pack containing battery cells. Feature 2: A power supply unit configured to be connected to a battery pack. Feature 3: A judgment power supply generating unit disposed in a battery pack or a power supply unit and configured to apply to a battery cell a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency. Feature 4: A first measuring unit disposed in the battery pack or the power supply unit, configured to measure a first current value flowing to the battery cell and a first voltage value of the battery cell corresponding to application of a first component to the battery cell, and a second current value flowing to the battery cell and a second voltage value of the battery cell corresponding to application of a second component to the battery cell. Feature 5: A judgment unit disposed in the battery pack or the power supply unit, the judgment unit configured to calculate a first impedance based on a first current value and a first voltage value measured by a first measurement unit, calculate a second impedance based on a second current value and a second voltage value measured by the first measurement unit, and judge that a battery cell is abnormal based on the first impedance and the second impedance.

[0016] The power supply system having at least the features 1 to 5 can calculate the impedance of the positive electrode and the impedance of the negative electrode of the battery cell by applying a signal including two different frequency components to the battery cell. The thermal stability of the battery cell tends to increase with an increase in the impedance of the positive electrode. The thermal stability of the battery cell tends to decrease with an increase in the impedance of the negative electrode. Therefore, the range of values ​​that the impedance of the positive electrode and the negative electrode can take when the battery cell has capacity degradation with a decrease in thermal stability is different from the range of values ​​that the impedance of the positive electrode and the negative electrode can take when the battery cell has capacity degradation without a decrease in thermal stability. Therefore, the power supply system can determine that the battery cell is in an abnormal state with a decrease in thermal stability based on the first impedance and the second impedance. Furthermore, when the thermal stability of the battery cell has decreased, the battery cell can be appropriately handled.

[0017] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5, the following features 6 to 8 may be provided. · Feature 6: The first component corresponds to the first signal. · Feature 7: The second component corresponds to a second signal that is separate from the first signal. Feature 8: The determination power supply generating unit applies the first signal and the second signal in sequence to the battery cell.

[0018] In a power supply system having at least the features 1 to 8, the first current value and the first voltage value, and the second current value and the second voltage value can be measured in that order.

[0019] In one embodiment, in addition to or instead of at least one of the features 1 to 8, the following feature 9 may be provided. Feature 9: The determination unit determines that the battery cell is abnormal based on a comparison result between the calculated first impedance and the calculated second impedance.

[0020] In the power supply system having at least the features 1 to 9, when the battery has a decrease in thermal stability, the first impedance is closer to the second impedance than when the battery has no decrease in thermal stability. Therefore, in the power supply system, it is possible to determine that the battery cell is abnormal based on the comparison result between the first impedance and the second impedance.

[0021] In one embodiment, in addition to or instead of at least one of the features 1 to 8, the following features 10 and 11 may be provided. Feature 10: A storage unit that stores a map in which the first impedance and the second impedance correspond to abnormal or normal states of the battery cell. Feature 11: The determination unit determines that the battery cell is abnormal, based on the calculated first impedance, the calculated second impedance, and the map.

[0022] A power supply system having at least the features 1 to 8 and 10 to 11 can determine that a battery cell is abnormal, based on the calculated first and second impedances and the map.

[0023] In one embodiment, in addition to or instead of at least one of the features 1 to 9 described above, at least one of the following features 12 and 13 may be provided. · Feature 12: The first frequency is higher than the second frequency. Feature 13: The determination unit determines that the battery cell is abnormal when a first ratio, which is a ratio of the first impedance to the second impedance, is equal to or greater than a first threshold value.

[0024] In a power supply system having at least the features 1 to 9 and 12 to 13, when a high frequency signal is applied to a battery cell, the impedance of the negative electrode is calculated, and when a low frequency signal is applied to the battery cell, the impedance of the positive electrode is calculated. In both cases where the thermal stability of the battery cell is high and where it is low, the impedance of the negative electrode is smaller than the impedance of the positive electrode. When the thermal stability of the battery cell decreases, the impedance of the negative electrode approaches the impedance of the positive electrode. Therefore, the power supply system can determine that the battery cell is in an abnormal state when the first ratio is equal to or greater than a first threshold value.

[0025] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 9 and 12 to 13, the following feature 14 may be provided. Feature 14: The determination unit determines that the battery cell is abnormal when the first ratio is less than the first threshold value and the first impedance is equal to or greater than the second threshold value.

[0026] In the power supply system having at least the features 1 to 8 and 12 to 14, when the difference between the impedance of the negative electrode and the impedance of the positive electrode is large when the thermal stability of the battery cell is high, the first ratio may be less than the first threshold even if the thermal stability of the battery cell is deteriorated. Even in such a case, the power supply system can determine that the battery cell is in an abnormal state in response to the deterioration of the thermal stability.

[0027] In one embodiment, in addition to or instead of at least one of the features 1 to 9 described above, at least one of the following features 15 and 16 may be provided. · Feature 15: The first frequency is higher than the second frequency. Feature 16: The determination unit determines that the battery cell is abnormal when the difference obtained by subtracting the first impedance from the second impedance is equal to or smaller than a third threshold value.

[0028] A power supply system having at least the features 1 to 8 and 15 to 16 can determine that a battery cell is in an abnormal state based on the difference.

[0029] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 9 and 15 to 16, the following feature 17 may be provided. Feature 17: The determination unit determines that the battery cell is abnormal when the difference is greater than the third threshold and the first impedance is equal to or greater than the fourth threshold.

[0030] A power supply system having at least features 1 to 9 and 15 to 17 can determine that a battery cell is in an abnormal state in response to deterioration of thermal stability, even if the difference between the impedance of the negative electrode and the impedance of the positive electrode is large when the thermal stability of the battery cell is high.

[0031] In some embodiments, in addition to or instead of at least one of the features 1 to 9 described above, at least one of the following features 18 and 19 may be provided. · Feature 18: The first frequency is higher than the second frequency. Feature 19: The determination unit determines that the battery cell is abnormal when the first impedance is equal to or greater than a fifth threshold and the second impedance is equal to or less than a sixth threshold.

[0032] A power supply system having at least the features 1 to 9 and 18 to 19 can determine that the battery pack is abnormal.

[0033] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 8, the following feature 20 may be provided. Feature 20: Each of the first signal and the second signal is an AC signal.

[0034] A power supply system having at least the features 1 to 8 and 20 can calculate the impedance of the positive electrode and the impedance of the negative electrode with high accuracy while maintaining the charge amount of the battery cell constant.

[0035] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 8, the following feature 21 may be provided. Feature 21: Each of the first signal and the second signal is a positive pulse signal and a negative pulse signal that appear alternately.

[0036] A power supply system having at least the features 1 to 8 and 21 can reduce the processing load for calculating impedance compared to the case where an AC signal is applied to the battery cell, while maintaining a constant amount of charge in the battery cell.

[0037] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 8, the following feature 22 may be provided. Feature 22: Each of the first signal and the second signal is a continuous positive pulse signal.

[0038] A power supply system having at least features 1 to 8 and 22 can simplify the configuration of the judgment power supply generating unit and reduce the processing load for calculating impedance compared to a case in which a positive pulse signal and a negative pulse signal are alternately applied to the battery cell.

[0039] In one embodiment, in addition to at least one of the above-mentioned features 1 to 9 and 12 to 13, or at least one of the features 1 to 9 and 15 to 16, or at least one of the features 1 to 9 and 18 to 19, the present invention may have at least one of the following features 23 to 29. Feature 23: The determination power supply generating unit further applies, following the first signal and the second signal, a third signal having a third frequency higher than the second frequency to the battery cell. Feature 24: The first measuring unit measures a third current value flowing through the battery cell and a third voltage value of the battery cell in response to application of a third signal to the battery cell. Feature 25: The determination unit calculates a first complex impedance at the first frequency from the first voltage value and the first current value. Feature 26: The determination unit calculates a second complex impedance at the second frequency from the second voltage value and the second current value. Feature 27: The determination unit calculates a third complex impedance at the third frequency from the third voltage value and the third current value. Feature 28: The determination unit calculates the first impedance by subtracting the real part of the first complex impedance from the real part of the second complex impedance. Feature 29: The determination unit calculates the second impedance by subtracting the real part of the second complex impedance from the real part of the third complex impedance.

[0040] In a power supply system having at least features 1 to 9, 12 to 13, and 23 to 29, or features 1 to 9, 15 to 16, and 23 to 29, or features 1 to 9, 18 to 19, and 23 to 29, the first and second impedances corresponding to the resistance values ​​of the negative and positive electrodes can be calculated more easily than by fitting.

[0041] In one embodiment, in addition to at least one of the above-mentioned features 1 to 9 and 12 to 13, or at least one of the features 1 to 9 and 15 to 16, or at least one of the features 1 to 9 and 18 to 19, the present invention may have at least one of the following features 30 to 31. Feature 30: The determination unit calculates a first impedance, which is a complex impedance at a first frequency, from the first voltage value and the first current value. Feature 31: The determination unit calculates a second impedance, which is a complex impedance at the second frequency, from the second voltage value and the second current value.

[0042] In a power supply system having at least features 1 to 9, 12 to 13, and 30 to 31, or features 1 to 9, 15 to 16, and 30 to 31, or features 1 to 9, 18 to 19, and 30 to 31, the first and second impedances can be easily calculated by substituting the complex impedances of the negative and positive electrodes for the resistance values ​​of the negative and positive electrodes.

[0043] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5, at least one of the following features 32 to 33 may be provided. Feature 32: The battery pack includes a first measurement unit and a determination unit. Feature 33: The power supply unit includes a power supply generating unit for judgment.

[0044] In a power supply system having at least the features 1 to 5 and 32 to 33, the first measurement section and the determination section can be disposed in a battery pack, and the determination power supply generating section can be disposed in a power supply unit.

[0045] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5, the following feature 34 may be provided. Feature 34: The power supply unit includes a determination power supply generating section, a first measuring section, and a determination section.

[0046] In a power supply system having at least the features 1 to 5 and 34, the determination power supply generating section, the first measurement section, and the determination section can be disposed in the power supply unit.

[0047] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5, the following feature 35 may be provided. Feature 35: The power supply unit is a charger configured to charge the battery cell.

[0048] A power supply system having at least the features 1 to 5 and 35 can determine that a battery cell is abnormal when charging a battery pack.

[0049] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5 and 35, the following feature 21 may be provided. Feature 36: The determination power supply generating unit applies a signal to the battery cell when the battery pack is connected to the power supply unit and before the power supply unit starts charging the battery cell.

[0050] A power supply system having at least the features 1 to 5 and 35 to 36 can determine that a battery cell is abnormal before starting charging of the battery cell, and can change charging control of the battery cell when it is determined that the battery cell is abnormal.

[0051] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5 and 35, the following feature 37 may be provided. Feature 37: The determination power supply generating unit applies a signal to the battery cell when the battery pack is connected to the power supply unit and after the power supply unit has completed charging the battery cell.

[0052] A power supply system having at least the features 1 to 5, 35, and 37 performs abnormality determination for a battery cell when the battery cell is in a stable fully charged state, thereby increasing the opportunities for performing abnormality determination for a battery cell.

[0053] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5 and 35, at least one of the following features 38 to 39 may be provided. Feature 38: When the determination unit determines that the battery cell is abnormal, the battery pack changes the control of the battery cell. Feature 39: When the determination unit determines that the battery cell is abnormal, the charger changes control of charging the battery cell.

[0054] A power supply system having at least the features 1 to 5, 35, and 38 or the features 1 to 8, 35, and 38 can protect a battery cell by changing control of the battery cell or charging control when it is determined that the battery cell is abnormal.

[0055] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5 and 35, the following feature 40 may be provided. Feature 40: When the determination unit determines that the battery cell is abnormal, the charger suppresses charging of the battery cell.

[0056] A power supply system having at least the features 1 to 5, 35, and 40 can protect a battery cell by suppressing charging the battery cell when it is determined that the battery cell is abnormal.

[0057] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5 and 35, at least one of the following features 41 to 42 may be provided. · Feature 41: The battery pack further includes a second measurement unit configured to measure the temperature of the battery cell. Feature 42: The charger suppresses charging of the battery cell when the determination unit determines that the battery cell is abnormal and the temperature measured by the second measurement unit is equal to or lower than a predetermined value.

[0058] A power supply system having at least the features 1 to 5, 35, 41, and 42 can protect a battery cell by suppressing charging to the battery cell when the battery cell is determined to be abnormal and the temperature of the battery cell is equal to or lower than a predetermined value.

[0059] In one embodiment, in addition to or instead of at least one of the above-mentioned features 1 to 5 and 35, the following feature 43 may be provided. Feature 43: When the determination unit determines that the battery cell is abnormal, the battery pack prohibits discharging from the battery cell or changes the conditions for permitting discharging from the battery cell.

[0060] A power supply system having at least features 1 to 8, 35, and 43 can protect a battery cell by prohibiting discharge from the battery cell or changing the conditions for allowing discharge from the battery cell when it is determined that the battery cell is abnormal.

[0061] In an embodiment, a method may be provided having at least one of the following features 44-48. · Feature 44: Applying to the battery cell a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency. Feature 45: Measuring a first current value flowing through the battery cell and a first voltage value of the battery cell corresponding to application of a first component to the battery cell, and a second current value flowing through the battery cell and a second voltage value of the battery cell corresponding to application of a second component to the battery cell. Feature 46: A first impedance is calculated based on the first current value and the first voltage value. Feature 47: A second impedance is calculated based on the second current value and the second voltage value. ·Feature 48: Determining that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance.

[0062] By carrying out the method having at least the features 44 to 48, the same effects as those of the power supply system having the features 1 to 5 described above can be achieved.

[0063] In one embodiment, a battery pack having at least one of the following features 49-52 may be provided. Feature 49: Battery Cell. · Feature 50: A judgment power supply generating unit configured to apply to a battery cell a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency. Feature 51: A measurement unit configured to measure a first current value flowing to the battery cell and a first voltage value of the battery cell corresponding to application of a first component to the battery cell, and a second current value flowing to the battery cell and a second voltage value of the battery cell corresponding to application of a second component to the battery cell. Feature 52: A determination unit configured to calculate a first impedance based on a first current value and a first voltage value measured by the measurement unit, calculate a second impedance based on a second current value and a second voltage value measured by the measurement unit, and determine that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance.

[0064] A battery pack having at least the features 49 to 52 has the same effects as a power supply system having the features 1 to 5 described above.

[0065] In one embodiment, a battery pack having at least one of the following features 53-56 may be provided. Feature 53: Battery Cell. Feature 54: A current measuring unit configured to measure and output a value of a current flowing from a battery cell. Feature 55: A voltage measuring unit configured to measure and output a voltage value of a battery cell. Feature 56: A control unit configured to calculate a deterioration parameter of a positive electrode of a battery cell and a deterioration parameter of a negative electrode of the battery cell based on input current values ​​and voltage values, and to perform charge / discharge control of the battery cell based on the calculated deterioration parameters of the positive electrode and the negative electrode.

[0066] A battery pack having at least the features 53 to 56 calculates deterioration parameters of each of the positive and negative electrodes of a battery cell. A battery cell tends to have low thermal stability when the positive electrode is not deteriorated, and high thermal stability when the positive electrode is deteriorated. A battery cell tends to have low thermal stability when the negative electrode is deteriorated, and high thermal stability when the negative electrode is not deteriorated. Therefore, the range of values ​​that the two deterioration parameters can take when the thermal stability of the battery cell is reduced is different from the range of values ​​that the two deterioration parameters can take when the thermal stability of the battery cell is not reduced. The above battery pack performs charging control of the battery cell based on the two deterioration parameters, so that the battery cell can be appropriately handled when the thermal stability of the battery cell is reduced.

[0067] (First embodiment) <1-1. System configuration> The configuration of a power supply system 1A according to a first embodiment will be described with reference to Fig. 1. The power supply system 1A includes a battery pack 10A and a charger 50A. In this embodiment, the charger 50A corresponds to an example of a power supply unit of the present disclosure.

[0068] The battery pack 10A is a power source for an electric work machine. The battery pack 10A is connected to the electric work machine and supplies power to the connected electric work machine. The electric work machine includes an electric tool, a gardening tool, etc. The electric tool includes an impact driver, a chain saw, etc. The gardening tool includes a grass cutter, a trimmer, etc.

[0069] The battery pack 10A includes a first connection portion 20A that is connected to a charger 50A or an electric operating machine. The first connection portion 20A includes a first positive terminal 21, a first negative terminal 22, and a first communication terminal .

[0070] The battery pack 10A includes a battery cell 31. The battery cell 31 includes a plurality of cells connected in series. The battery cell 31 is a chargeable and dischargeable secondary battery, for example, a lithium ion battery.

[0071] The battery pack 10A includes an interrupting element 34 on a first positive line 37. The first positive line 37 connects the positive electrode of the battery cell 31 to the first positive terminal 21. The interrupting element 34 is controlled by a battery microcontrol unit (hereinafter, battery MCU) 33 described later, and conducts or electrically interrupts the first positive line 37. The interrupting element 34 includes at least one of a field effect transistor (hereinafter, FET), a self-blown fuse (SCP), and the like.

[0072] The battery pack 10A includes a first shunt resistor 35 on a first negative electrode line 38. The first negative electrode line 38 connects the negative electrode of the battery cell 31 to the first negative electrode terminal 22. The first shunt resistor 35 generates a voltage according to the magnitude of the charging current or discharging current flowing through the first shunt resistor 35, and outputs the generated voltage to a current / voltage monitoring circuit 32 described later.

[0073] The battery pack 10A includes a current / voltage monitoring circuit 32. The current / voltage monitoring circuit 32 is connected to the battery cell 31, and measures the battery voltage value of the battery cell 31. The battery voltage value corresponds to the magnitude of the output voltage of the battery cell 31.

[0074] The current / voltage monitoring circuit 32 is connected to the first shunt resistor 35, and measures the battery current value based on the voltage input from the first shunt resistor 35. The battery current value corresponds to the magnitude of the charging current flowing into the battery cell 31, or the magnitude of the discharging current flowing out of the battery cell 31.

[0075] The current and voltage monitoring circuit 32 is connected to the battery MCU 33, and outputs the measured battery voltage value and battery current value to the battery MCU 33. In this embodiment, the current and voltage monitoring circuit 32 corresponds to an example of a first measurement unit and a measurement unit of the present disclosure.

[0076] The battery pack 10A includes a temperature measurement unit 36. The temperature measurement unit 36 ​​is disposed near the battery cell 31 and measures the battery temperature of the battery cell 31. The temperature measurement unit 36 ​​is connected to the battery MCU 33 and outputs the measured battery temperature to the battery MCU 33. In this embodiment, the temperature measurement unit 36 ​​corresponds to an example of a second measurement unit of the present disclosure.

[0077] The battery pack 10A includes a battery MCU 33. The battery MCU 33 has the form of a microcomputer including a CPU, a memory, an I / O, and the like, and realizes various functions by the CPU executing a program stored in the memory.

[0078] The battery MCU 33 executes an abnormality determination process, a charging control, and a discharging control of the battery cell 31. The battery MCU 33 performs serial communication with the charger 50A via the first communication terminal 23, and acquires information related to charging from the charger 50A. The battery MCU 33 determines whether the battery cell 31 is abnormal or not based on the battery voltage value, the battery current value, and the information related to charging, and executes the charging control of the battery cell 31. Furthermore, when the battery pack 10A is connected to the electric work machine, the battery MCU 33 performs serial communication with the electric work machine and acquires the information related to the electric work machine. The battery MCU 33 determines whether the battery cell 31 is abnormal or not based on the battery voltage value, the battery current value, and the information related to the electric work machine, and executes the discharging control of the battery cell 31. In this embodiment, the battery MCU 33 corresponds to an example of a determination unit of the present disclosure.

[0079] The charger 50A includes a second connection unit 60A that is connected to the battery pack 10A. The second connection unit 60A includes a second positive terminal 61, a second negative terminal 62, and a second communication terminal 63. The second positive terminal 61 is connected to the first positive terminal 21. The second negative terminal 62 is connected to the first negative terminal 22. The second communication terminal 63 is connected to the first communication terminal 23.

[0080] The charger 50A includes a switching power supply circuit 51. The switching power supply circuit 51 is connected to a charger MCU 54 described later, and is also connected to an AC external power supply (for example, a 100V commercial power supply) via a power cord. Based on a command from the charger MCU 54, the switching power supply circuit 51 generates DC power to be supplied to the battery pack 10A from AC power input from the external power supply. The switching power supply circuit 51 is also connected to a DC / AC inverter circuit 52 described later, and outputs a DC signal to the DC / AC inverter circuit 52 based on a command from the charger MCU 54.

[0081] The charger 50A includes a DC / AC inverter circuit 52. The DC / AC inverter circuit 52 is connected to the charger MCU 54. The DC / AC inverter circuit 52 receives a command from the charger MCU 54 and generates an AC signal having the commanded frequency from the DC power input from the switching power supply circuit 51. In detail, as shown in Fig. 4, the DC / AC inverter circuit 52 sequentially generates a plurality of AC signals having different frequencies from the DC power.

[0082] The charger 50A includes a selector 53. The selector 53 is controlled by the charger MCU 54 to connect the second positive line 77 to the switching power supply circuit 51 or the DC / AC inverter circuit 52. The second positive line 77 is connected to the second positive terminal 61. When the charger MCU 54 selects the switching power supply circuit 51, the second positive terminal 61 is connected to the switching power supply circuit 51 via the second positive line 77. This allows DC power to be supplied from the switching power supply circuit 51 to the battery cell 31. When the charger MCU 54 selects the DC / AC inverter circuit 52, the second positive terminal 61 is connected to the DC / AC inverter circuit 52 via the second positive line 77. This allows a plurality of AC signals to be applied in sequence from the DC / AC inverter circuit 52 to the battery cell 31. In this embodiment, the DC / AC inverter circuit 52 corresponds to an example of a determination power supply generating unit of the present disclosure.

[0083] The charger 50A includes a FET 55 on the second positive line 77. The FET 55 is turned on or off by the charger MCU 54. When the FET 55 is on, the second positive line 77 is conductive, and when the FET 55 is off, the second positive line 77 is electrically cut off.

[0084] The charger 50A includes a second shunt resistor 56 on a second negative electrode line 78. The second negative electrode line 78 connects the second negative electrode terminal 62 to the switching power supply circuit 51 and the DC / AC inverter circuit 52. The second shunt resistor 56 generates a voltage according to the magnitude of the charging current flowing through the second shunt resistor 56, and outputs the generated voltage to the charger MCU 54.

[0085] The charger 50A includes a charger MCU 54. The charger MCU 54 has the form of a microcomputer including a CPU, a memory, an I / O, and the like, and realizes various functions by the CPU executing a program stored in the memory.

[0086] The charger MCU 54 executes abnormality determination processing and charging control of the battery cells 31. The charger MCU 54 performs serial communication with the battery pack 10A via the second communication terminal 63, and acquires information about the battery pack 10A from the battery pack 10A. The charger MCU 54 is connected to the second shunt resistor 56, and measures a charging current value based on a voltage input from the second shunt resistor 56. The charging current value corresponds to the magnitude of the charging current flowing from the charger 50A to the battery pack 10A.

[0087] The charger MCU 54 controls the selector 53, the switching power supply circuit 51, the DC / AC inverter circuit 52, and the FET 55 based on information about the battery pack 10A and the charging current value. In another embodiment, the first connection unit 20A may further include a third communication terminal 26 connected to the temperature measurement unit 36. The second connection unit 60A may further include a fourth communication terminal 66 connected to the charger MCU 54. The fourth communication terminal 66 is connected to the third communication terminal 26. The charger MCU 54 may obtain the battery temperature measured by the temperature measurement unit 36 ​​via the fourth communication terminal 66 and perform charging control using the battery temperature.

[0088] <1-2. Processing> <1-2-1. Charging control process> The charging control process executed by the battery MCU 33 and the charger MCU 54 according to the first embodiment will be described with reference to Fig. 2. When the battery MCU 33 detects that the battery pack 10A is connected to the charger 50A, the battery MCU 33 starts this process and executes this process repeatedly at a predetermined cycle. When the charger MCU 54 detects that the charger 50A is connected to the battery pack 10A, the battery MCU 33 starts this process and executes this process repeatedly at a predetermined cycle.

[0089] In S5, the charger MCU 54 sets the current output current value Inow to 0A. Next, in S10, the battery MCU 33 and the charger MCU 54 perform initial communication with each other. The battery MCU 33 transmits information about the battery pack 10A, such as the model number of the battery pack 10A, to the charger MCU 54. The charger MCU 54 transmits information about the charger 50A, such as the model number of the charger 50A, to the battery MCU 33.

[0090] Next, in S20, the battery MCU 33 and the charger MCU 54 execute an abnormality determination process. More specifically, the battery MCU 33 and the charger MCU 54 determine whether the battery cell 31 is in an abnormally deteriorated state. The abnormally deteriorated state is a state in which the thermal stability of the battery cell 31 is reduced and the capacity is deteriorated. More specifically, the abnormally deteriorated state is a state in which lithium deposition or the like occurs in the negative electrode of the battery cell 31. In this embodiment, capacity deterioration accompanied by a reduction in the thermal stability of the battery cell 31 is referred to as abnormal deterioration, and capacity deterioration not accompanied by a reduction in the thermal stability of the battery cell 31 is referred to as normal deterioration.

[0091] When the battery pack 10A is repeatedly charged and discharged in a low-temperature environment, lithium deposition and / or lithium alkoxide generation occurs in the negative electrode of the battery cell 31, the negative electrode deteriorates, and the increase in the negative electrode resistance value R1 becomes larger than when the battery pack 10A is repeatedly charged and discharged in an appropriate temperature range. The low-temperature environment is a temperature environment that is lower than the temperature range suitable for using the battery pack 10A.

[0092] FIG. 3 shows an example of the relationship between the negative electrode resistance value R1 and the positive electrode resistance value R2 and the presence or absence of a decrease in thermal stability. The positive electrode resistance value R2 is very large (for example, about one order of magnitude larger) compared to the negative electrode resistance value R1. When the capacity of the battery cell 31 is not degraded, both the negative electrode resistance value R1 and the positive electrode resistance value R2 are small. The thermal stability of the battery cell 31 tends to increase with an increase in the positive electrode resistance value R2. That is, the thermal stability of the battery cell 31 tends to increase with the progress of the deterioration of the positive electrode. On the other hand, the thermal stability of the battery cell 31 tends to decrease with an increase in the negative electrode resistance value R1. That is, the thermal stability of the battery cell 31 tends to decrease with the progress of the deterioration of the negative electrode. Therefore, when the battery pack 10A is repeatedly charged and discharged in a low-temperature environment, the thermal stability of the battery cell 31 decreases and the capacity decreases.

[0093] The range of values ​​that the negative electrode resistance value R1 and the positive electrode resistance value R2 can take when abnormal deterioration occurs is different from the range of values ​​that the negative electrode resistance value R1 and the positive electrode resistance value R2 can take when normal deterioration occurs. As shown in FIG. 3, when abnormal deterioration occurs, the negative electrode resistance value R1 tends to be larger and the positive electrode resistance value R2 tends to be smaller than when normal deterioration occurs. Therefore, when abnormal deterioration occurs, the negative electrode resistance value R1 tends to approach the positive electrode resistance value R2 compared to when normal deterioration occurs. In this embodiment, based on the tendency of the negative electrode resistance value R1 and the positive electrode resistance value R2, abnormal deterioration of the battery cell 31 is determined to be normal capacity deterioration in which thermal stability does not decrease. Details of the abnormality determination process will be described later.

[0094] Next, in S30, the battery MCU 33 determines whether charging is permitted. In particular, if the charger 50A is suitable for charging the battery cell 31, the battery MCU 33 determines that charging is permitted (S30: YES) and proceeds to processing of S50. If the charger 50A is not suitable for charging the battery cell 31, the battery MCU 33 determines that charging is not permitted (S30: NO) and proceeds to processing of S40.

[0095] In S40, the battery MCU 33 sets charging to be prohibited, and ends this process. In S50, the battery MCU 33 acquires the battery voltage value and the battery temperature. Next, in S60, the battery MCU 33 determines whether to wait for charging. If the battery temperature is below the low-temperature standby temperature, the battery MCU 33 determines to wait for charging, and if the battery temperature is equal to or higher than the low-temperature standby temperature, the battery MCU 33 determines to execute charging. If the battery MCU 33 determines to wait for charging (S60: YES), it returns to the process of S30, and if it determines to execute charging (S60: NO), it proceeds to the process of S70.

[0096] Next, in S70, the battery MCU 33 determines the initial allowable current value Inext based on the battery voltage value and the battery temperature acquired in S50. The allowable current value Inext corresponds to the upper limit of the current that can be passed to the battery cell 31.

[0097] Next, in S80, the battery MCU 33 communicates with the charger MCU 54 and notifies the charger MCU 54 of the allowable current value Inext determined in S70. Next, in S15, the charger MCU 54 acquires the charger temperature measured by a temperature measuring unit arranged in the charger 50A.

[0098] Next, in S25, the charger MCU 54 determines the current output upper limit value Icm based on the charger temperature acquired in S15. The output upper limit value Icm corresponds to the upper limit value of the output current that can be output from the charger 50A.

[0099] Next, in S35, the charger MCU 54 determines the output current value Inow based on the allowable current value Inext and the output upper limit value Icm. Specifically, the charger MCU 54 sets the smaller of the allowable current value Inext and the output upper limit value Icm as the output current value Inow.

[0100] Next, in S45, the charger MCU 54 outputs the output current having the output current value Inow determined in S35 to the battery pack 10A. Next, in S55, the charger MCU 54 communicates with the battery MCU 33 and notifies the battery MCU 33 of the current output current value Inow.

[0101] Next, in S90, the battery MCU 33 acquires the battery voltage value and the battery temperature. Next, in S100, the battery MCU 33 determines whether charging is complete based on the battery voltage value acquired in S90. If the battery MCU 33 determines that charging is not complete (S100: NO), the process proceeds to S110, and if the battery MCU 33 determines that charging is complete (S100: YES), the process proceeds to S120.

[0102] In S110, the battery MCU 33 calculates the allowable current value Inext based on the battery voltage value and the battery temperature acquired in S90, and returns to the process of S80. In S120, the battery MCU 33 sets the allowable current value Inext to zero.

[0103] Next, in S130, the battery MCU 33 communicates with the charger MCU 54 and notifies the charger MCU 54 of the completion of charging. In S65, the charger MCU 54 determines whether or not a charging completion notification has been received. If the charger MCU 54 determines that a charging completion notification has been received (S65: YES), the charger MCU 54 proceeds to the process of S140. If the charger MCU 54 determines that a charging completion notification has not been received, the charger MCU 54 returns to the process of S80 and receives the allowable current value Inext from the battery MCU 33.

[0104] In S140, similarly to the process of S20, the battery MCU 33 and the charger MCU 54 execute the abnormality determination process. That is, the battery MCU 33 and the charger MCU 54 execute the abnormality determination process before the start of charging the battery cell 31 and after the completion of charging. In another embodiment, the battery MCU 33 and the charger MCU 54 may execute the abnormality determination process either before the start of charging the battery cell 31 or after the completion of charging.

[0105] When the first connection unit 20A includes the third communication terminal 26 and the second connection unit 60A includes the fourth communication terminal 66, the charger MCU 54 may execute the process of S60.

[0106] <1-2-2. First example of abnormality determination processing> A first example of the abnormality determination process executed by the battery MCU 33 and the charger MCU 54 in S20 and S140 will be described with reference to FIG.

[0107] In S105, the charger MCU 54 waits. In S160, the battery MCU 33 acquires the state of the battery cell 31. Specifically, the battery MCU 33 acquires the battery temperature, the battery voltage value, the charge state, the usage history, and the degree of deterioration of the capacity.

[0108] Next, in S170, the battery MCU 33 determines whether or not to perform abnormal degradation determination based on the state of the battery cell 31 acquired in S160. When the number of times the battery cell 31 has been used is small, the magnitudes of the negative electrode resistance value R1 and the positive electrode resistance value R2 are small. Therefore, the battery cell 31 may be determined to be in an abnormal degradation state with a small difference between the negative electrode resistance value R1 and the positive electrode resistance value R2. In addition, when the battery temperature is high, when the battery voltage value is outside a predetermined range, or when the charge amount is small, the accuracy of the abnormal degradation determination may decrease. Therefore, when the battery MCU 33 can accurately determine the abnormal degradation of the battery cell 31, it determines to perform the abnormal degradation determination, and when it cannot accurately determine the abnormal degradation determination, it determines not to perform the abnormal degradation determination. When the battery MCU 33 determines to perform the abnormal degradation determination (S170: YES), it proceeds to the process of S180, and when it determines not to perform the abnormal degradation determination (S170: NO), it proceeds to the process of S190.

[0109] In S180, the battery MCU 33 sets the impedance measurement flag to ON, and proceeds to the process of S200. In S190, the battery MCU 33 sets the impedance measurement flag to OFF, and proceeds to the process of S200.

[0110] In S200, the battery MCU 33 communicates with the charger MCU 54 and notifies the charger MCU 54 that impedance measurement is necessary if the impedance measurement flag is on, and notifies the charger MCU 54 that impedance measurement is not necessary if the impedance measurement flag is off.

[0111] In S115, the charger MCU 54 determines whether or not to perform impedance measurement based on the necessity of impedance measurement notified from the battery MCU 33. If the charger MCU 54 determines to perform impedance measurement (S115: YES), the charger MCU 54 proceeds to processing of S125, and if the charger MCU 54 determines not to perform impedance measurement (S115: NO), the charger MCU 54 ends this processing.

[0112] In S125, the charger MCU 54 switches the connection target of the selector 53 from the switching power supply circuit 51 to the DC / AC inverter circuit 52. As a result, the DC / AC inverter circuit 52 is connected to the second positive electrode line 77.

[0113] In S135, as shown in FIG. 5A, the charger MCU 54 instructs the DC / AC inverter circuit 52 to output a plurality of AC signals having different frequencies in sequence. On the other hand, in S210, the battery MCU 33 determines whether or not to perform impedance measurement based on the impedance measurement flag. If the battery MCU 33 determines to perform impedance measurement (S210: YES), the process proceeds to S220, and if the battery MCU 33 determines not to perform impedance measurement (S210: NO), the process ends.

[0114] In S220, the battery MCU 33 acquires a plurality of battery voltage values ​​and a plurality of battery current values ​​measured by the current / voltage monitoring circuit 32, and acquires a battery temperature measured by the temperature measurement unit 36. Each of the plurality of battery voltage values ​​corresponds to a battery voltage value when a plurality of AC signals having different frequencies are applied to the battery cell 31, and has a different frequency. Each of the plurality of battery current values ​​corresponds to a battery current value when a plurality of AC signals having different frequencies are applied to the battery cell 31, and has a different frequency.

[0115] In S230, the battery MCU 33 communicates with the charger MCU 54 and notifies it that the impedance measurement has been completed. In S145, the charger MCU 54 switches the connection target of the selector 53 from the DC / AC inverter circuit 52 to the switching power supply circuit 51.

[0116] In S155, the charger MCU 54 waits. On the other hand, in S240, the battery MCU 33 calculates the impedance Z(fk) from the AC voltage value and the AC current value at each of a plurality of frequencies. In the plot diagram shown in FIG. 5B, each point corresponds to a different frequency, the horizontal axis indicates the real part of the impedance Z(fk), and the vertical axis indicates the imaginary part of the impedance Z(fk).

[0117] The impedance Z(fk) represents the difficulty of current flow for an AC signal. The frequency at which current does not easily flow to the negative electrode of the battery cell 31 is different from the frequency at which current does not easily flow to the positive electrode of the battery cell 31. In other words, the frequency characteristics of the negative electrode impedance are different from the frequency characteristics of the positive electrode impedance. Therefore, each of the negative electrode impedance and the positive electrode impedance can be calculated from the difference in frequency characteristics between the negative electrode impedance and the positive electrode impedance.

[0118] The frequency characteristics of the negative electrode impedance and the positive electrode impedance are obtained in advance by experiment or simulation. In this embodiment, the frequency characteristics of the negative electrode impedance that is large in the first frequency region and the frequency characteristics of the positive electrode impedance that is large in the second frequency region are obtained in advance by experiment. Furthermore, the frequency characteristics of the Wargburg impedance W that is large in the third frequency region are obtained. The first frequency region has a higher frequency than the second frequency region, and the second frequency region has a higher frequency than the third frequency region.

[0119] Next, in S250, the battery MCU 33 calculates the negative electrode resistance value R1 and the positive electrode resistance value R2. In this embodiment, the battery MCU 33 calculates the negative electrode resistance value R1 and the positive electrode resistance value R2 by fitting an equivalent circuit of the battery cell 31 to the actual measurement value of the obtained impedance Z(fk). As shown in Fig. 5, the equivalent circuit of the battery cell 31 is modeled from the resistance value Rs of the electrolyte, the negative electrode resistance value R1, the negative electrode capacity C1, the positive electrode resistance value R2, the positive electrode capacity C2, and the Wargburg impedance W.

[0120] The battery MCU 33 calculates parameters R1, R2, C1, and C2 that minimize h(R1, R2, C1, C2, W). h(R1, R2, C1, C2, W) is the sum of squares of the absolute values ​​of the differences between the actual measurement value Z(fk) and the impedance Zm(fk, R1, R2, C1, C2, W) of the equivalent circuit at each frequency fk (k=1, 2, ... N) (i.e., the sum of squares of the Euclidean distances). Each frequency fk is included in the frequencies of the multiple AC signals.

[0121] Since h(R1, R2, C1, C2, W) is a nonlinear equation with respect to the parameters, one optimal solution cannot be obtained. Therefore, the battery MCU 33 calculates the parameters R1, R2, C1, and C2 to be minimized, for example, using an algorithm such as the gradient method or the Newton method. However, at the time of calculation, it is not possible to determine which of the two resistance values ​​is the negative electrode resistance value R1 and which is the positive electrode resistance value R2. The battery MCU 33 determines one of the two calculated resistance values ​​as the negative electrode resistance value R1 and the other as the positive electrode resistance value R2 based on the frequency characteristics of the negative electrode impedance and the positive electrode impedance obtained in advance. In this embodiment, the negative electrode resistance value R1 corresponds to an example of the first impedance of the present disclosure, and the positive electrode resistance value R2 corresponds to an example of the second impedance of the present disclosure. Also, in this embodiment, the negative electrode resistance value R1 corresponds to an example of the deterioration parameter of the negative electrode of the present disclosure, and the positive electrode resistance value R2 corresponds to an example of the deterioration parameter of the positive electrode of the present disclosure.

[0122] Next, in S260, the battery MCU 33 determines whether the comparison result between the negative electrode resistance value R1 and the positive electrode resistance value R2 is within the normal range. Specifically, the battery MCU 33 determines whether the ratio R1 / R2 is less than the first threshold value Tha. When the battery cell 31 is not degraded, the negative electrode resistance value R1 is smaller than the positive electrode resistance value R2. When the battery cell 31 is in an abnormally degraded state, the negative electrode resistance value R1 is larger and the positive electrode resistance value R2 is smaller than when the battery cell 31 is in a normally degraded state. As a result, the ratio R1 / R2 increases.

[0123] The battery MCU 33 determines that the comparison result is out of the normal range when the ratio R1 / R2 is equal to or greater than the first threshold value Tha, and determines that the comparison result is in the normal range when the ratio R1 / R2 is less than the first threshold value Tha. Also, the battery MCU 33 determines that the comparison result is out of the normal range when the ratio R1 / R2 is less than the first threshold value Tha and the negative electrode resistance value R1 is equal to or greater than the second threshold value Thb.

[0124] Alternatively, the battery MCU 33 determines whether the difference R2-R1 obtained by subtracting the negative electrode resistance value R1 from the positive electrode resistance value R2 is greater than the third threshold value Thc. When the difference R2-R1 is equal to or less than the third threshold value Thc, the battery MCU 33 determines that the comparison result is outside the normal range, and when the difference R2-R1 is greater than the third threshold value Thc, the battery MCU 33 determines that the comparison result is within the normal range. Moreover, when the difference R2-R1 is greater than the third threshold value Thc and the negative electrode resistance value R1 is equal to or greater than the fourth threshold value Thd, the battery MCU 33 determines that the comparison result is outside the normal range. The fourth threshold value Thd may be the same value as the second threshold value Thb.

[0125] Alternatively, the battery MCU 33 determines that the comparison result is outside the normal range when the negative electrode resistance value R1 is equal to or greater than the fifth threshold value The and the positive electrode resistance value R is equal to or less than the sixth threshold value Thf. The fifth threshold value The may be the same value as the second threshold value Thb.

[0126] If the battery MCU 33 determines that the comparison result is outside the normal range (S260: NO), it proceeds to processing of S270, and if the battery MCU 33 determines that the comparison result is within the normal range (S260: YES), it proceeds to processing of S280.

[0127] In S270, the battery MCU 33 determines that the battery cell 31 is in an abnormally deteriorated state, and sets the abnormally deteriorated flag to ON. Next, in S280, the battery MCU 33 stores the currently calculated parameters R1, R2, C1, and C2 in the memory of the battery MCU 33, and ends this process.

[0128] <1-2-3. Second example of abnormality determination processing> A second example of the abnormality determination process executed by the battery MCU 33 and the charger MCU 54 in S20 and S140 will be described with reference to FIG.

[0129] The charger MCU 54 executes the same process as the first example of the abnormality determination process shown in FIG. The battery MCU 33 executes processing of S300 instead of processing of S250 in the first example of the abnormality determination processing shown in FIG. 4, and executes processing similar to that of the first example of the abnormality determination processing shown in FIG. 4 except for the processing of S250.

[0130] In S300, as shown in Fig. 7, the battery MCU 33 estimates the negative electrode resistance value R1 and the positive electrode resistance value R2 based on the difference between the real parts of the impedance Z(fk) at the first frequency f1, the second frequency f2, and the third frequency f3. The first frequency f1, the second frequency f2, and the third frequency f3 are frequencies at which the frequency characteristics of the impedance Z(fk) change, and are determined in advance by experiment or simulation. The range from the first frequency f1 to the second frequency f2 corresponds to a first frequency region where the negative electrode impedance is large, and the range from the second frequency f2 to the third frequency f3 corresponds to a second frequency region where the positive electrode impedance is large.

[0131] The battery MCU 33 calculates the negative electrode resistance value R1 by subtracting the real part of the impedance Z(f1) from the real part of the impedance Z(f2). The battery MCU 33 also calculates the positive electrode resistance value R2 by subtracting the real part of the impedance Z(f2) from the real part of the impedance Z(f3). The impedance Z(f1) is the impedance at the first frequency f1. The impedance Z(f2) is the impedance at the second frequency f2. The impedance Z(f3) is the impedance at the third frequency f3.

[0132] In the second example of the abnormality determination process, the DC / AC inverter circuit 52 may generate three AC signals having different frequencies in sequence. That is, the DC / AC inverter circuit 52 may generate a first AC signal having a first frequency f1, a second AC signal having a second frequency f2, and a third AC signal having a third frequency f3 in sequence. The first frequency f1 is higher than the second frequency f2, and the second frequency f2 is higher than the third frequency f3.

[0133] <1-2-4. Discharge control process> The discharge control process executed by the battery MCU 33 and the charger MCU 54 will be described with reference to Fig. 8. The battery MCU 33 starts this process when it detects that the battery pack 10A is connected to an electric work machine.

[0134] In S1100, the battery MCU 33 performs initial communication with the electric work machine, transmits information about the battery pack 10A, and receives information about the electric work machine. Next, in S1110, the battery MCU 33 determines whether the abnormal degradation flag is set to ON. If the battery MCU 33 determines that the abnormal degradation flag is set to OFF (S1110: NO), the battery MCU 33 proceeds to processing of S1120, and if the battery MCU 33 determines that the abnormal degradation flag is set to ON (S1110: YES), the battery MCU 33 proceeds to processing of S1150.

[0135] In S1120, the battery MCU 33 sets the temperature threshold to the first temperature T1. Next, in S1130, the battery MCU 33 sets the overdischarge threshold to the first voltage value V1.

[0136] Next, in S1140, the battery MCU 33 sets the overcurrent threshold to the first current value I1, sets the overcurrent time to the first time Tm1, and proceeds to the process of S1180. In S1150, the battery MCU 33 sets the temperature threshold to a second temperature T2. The second temperature T2 is lower than the first temperature T1.

[0137] Next, in S1160, the battery MCU 33 sets the overdischarge threshold to a second voltage value V2. The second voltage value V2 is higher than the first voltage value V1. Next, in S1170, the battery MCU 33 sets the overcurrent threshold to a second current value I2, sets the overcurrent time to a second time Tm2, ​​and proceeds to the process of S1180. The second current value I2 is smaller than the first current value I1. The second time Tm2 is shorter than the first time Tm1.

[0138] In S1180, the battery MCU 33 determines whether discharging is permitted. If the battery MCU 33 determines that discharging is permitted (S1180: YES), the battery MCU 33 proceeds to processing of S1190, and if the battery MCU 33 determines that discharging is not permitted (S1180: NO), the battery MCU 33 proceeds to processing of S1200.

[0139] In S1190, the battery MCU 33 determines permission for discharge, and proceeds to the process of S1210. In S1200, the battery MCU 33 determines to prohibit discharging, and proceeds to S1210. In S1210, the battery MCU 33 periodically communicates with the electric work machine and notifies the electric work machine of the determined discharge permission or discharge prohibition.

[0140] In S1220, the battery MCU 33 acquires the battery temperature, the battery voltage value, and the discharge current value. Next, in S1230, the battery MCU 33 determines whether the battery cell 31 is in an over-discharged state based on the over-discharge threshold set in S1130 or S1160. Specifically, the battery MCU 33 determines that the battery cell 31 is in an over-discharged state when the battery voltage value acquired in S1220 is less than the over-discharge threshold. Therefore, when the battery cell 31 is in an abnormally deteriorated state, the standard for determining whether the battery cell 31 is in an over-discharged state is stricter than when the battery cell 31 is not in an abnormally deteriorated state.

[0141] If the battery MCU 33 determines that the battery cell 31 is in an over-discharged state (S1230: YES), the process proceeds to S1260, and if the battery MCU 33 determines that the battery cell 31 is not in an over-discharged state (S1230: NO), the process proceeds to S1240.

[0142] In S1240, the battery MCU 33 determines whether the battery cell 31 is in an overcurrent state. Specifically, the battery MCU 33 determines that the battery cell 31 is in an overcurrent state when the battery current value acquired in S1220 is equal to or greater than the overcurrent threshold set in S1140 or S1170 and continues to flow for the overcurrent time set in S1140 or S1170. Therefore, when the battery cell 31 is in an abnormally deteriorated state, the standard for determining whether the battery cell 31 is in an overcurrent state is stricter than when the battery cell 31 is not in an abnormally deteriorated state.

[0143] If the battery MCU 33 determines that the battery cell 31 is in an overcurrent state (S1240: YES), the process proceeds to S1260, and if the battery MCU 33 determines that the battery cell 31 is not in an overcurrent state (S1240: NO), the process proceeds to S1250.

[0144] In S1250, the battery MCU 33 determines whether the battery cell 31 is in a high temperature state. Specifically, the battery MCU 33 determines whether the battery temperature acquired in S1220 is equal to or higher than the temperature threshold value set in S1120 or S1150. Therefore, when the battery cell 31 is in an abnormally deteriorated state, the standard for determining whether the battery cell 31 is in a high temperature state is stricter than when the battery cell 31 is not in an abnormally deteriorated state.

[0145] If the battery MCU 33 determines that the battery cell 31 is in a high temperature state (S1250: YES), the process proceeds to S1260, and if the battery MCU 33 determines that the battery cell 31 is not in a high temperature state (S1250: NO), the process proceeds to S1270.

[0146] In S1260, the battery MCU 33 determines to prohibit discharging of the battery cell 31, and the process returns to S1210. In S1270, the battery MCU 33 determines permission to discharge the battery cell 31, and returns to the process of S1210.

[0147] <1-3.Effects> According to the first embodiment described above in detail, the following effects are achieved. (1) By applying a plurality of AC signals having different frequencies to the battery cell 31, the battery MCU 33 can calculate the negative electrode resistance value R1 and the positive electrode resistance value R2. When abnormal deterioration of the battery cell 31 occurs, the negative electrode resistance value R1 is larger and the positive electrode resistance value R2 is smaller than when normal deterioration of the battery cell 31 occurs. That is, the negative electrode resistance value R1 approaches the positive electrode resistance value R2. Therefore, based on the comparison result between the negative electrode resistance value R1 and the positive electrode resistance value R2, the battery MCU 33 can determine that the battery cell 31 is in a deteriorated state in which the thermal stability has decreased. In addition, when the thermal stability of the battery cell 31 has decreased, the battery cell 31 can be appropriately handled.

[0148] (2) When the ratio R1 / R2 is equal to or greater than the first threshold value Tha, the battery MCU 33 can determine that the battery cell 31 is in an abnormally deteriorated state. (3) The battery MCU 33 can determine that the battery cell 31 is in an abnormally deteriorated state when the ratio R1 / R2 is less than the first threshold value Tha and the negative electrode resistance value R1 is equal to or greater than the second threshold value Thb.

[0149] (4) When the difference R2-R1 is equal to or smaller than the third threshold value Thc, the battery MCU 33 can determine that the battery cell 31 is in an abnormally deteriorated state. (5) The battery MCU 33 can determine that the battery cell 31 is in an abnormally deteriorated state when the difference R2-R1 is greater than the third threshold value Thc and the negative electrode resistance value R1 is equal to or greater than the fourth threshold value Thd.

[0150] (6) The battery MCU 33 can determine that the battery cell 31 is in an abnormally deteriorated state when the negative electrode resistance value R1 is equal to or greater than the fifth threshold value The and the positive electrode resistance value R is equal to or less than the sixth threshold value Thf.

[0151] (7) By sequentially applying a plurality of AC signals to the battery cell 31, the charge amount of the battery cell 31 can be maintained constant and the negative electrode resistance value R1 and the positive electrode resistance value R2 can be calculated with high accuracy.

[0152] (8) The battery MCU 33 can determine that the battery cell 31 is in an abnormally deteriorated state before the charger 50A starts charging the battery cell 31. Furthermore, the battery MCU 33 can change the charging control of the battery cell 31 when it is determined that the battery cell 31 is in an abnormally deteriorated state.

[0153] (9) After the charging of the battery cell 31 is completed, the battery MCU 33 performs an abnormality determination for the battery cell 31. This increases the opportunities for performing an abnormality determination for the battery cell 31.

[0154] (10) When it is determined that the battery cell 31 is in an abnormally deteriorated state, the conditions for permitting discharge from the battery cell 31 are made stricter. This makes it possible to protect the battery cell 31.

[0155] Second embodiment <2-1. Differences from the first embodiment> The second embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0156] The power supply system 1A according to the first embodiment described above includes a battery pack 10A and a charger 50A. In contrast, the power supply system 1B according to the second embodiment includes a battery pack 10A and a charger 50B, and differs from the first embodiment in that the power supply system 1B executes the abnormality determination process shown in Fig. 10 or 12 instead of the abnormality determination process shown in Fig. 4 or 6.

[0157] The configuration of the charger 50B will be described with reference to Fig. 9. The basic configuration of the charger 50B is similar to that of the charger 50A. The charger 50B differs from the charger 50A in that the charger 50B includes a DC / DC inverter circuit 57 instead of the DC / AC inverter circuit 52.

[0158] The DC / DC inverter circuit 57 is connected to the charger MCU 54. The DC / DC inverter circuit 57 receives a command from the charger MCU 54 and generates a positive / negative pulse signal of a commanded frequency from the DC power input from the switching power supply circuit 51. The positive / negative pulse signal is a signal in which a positive pulse and a negative pulse appear alternately. The negative pulse is a pulse symmetrical to the positive pulse with respect to the zero level. In detail, the DC / DC inverter circuit 57 generates two or more positive / negative pulse signals having different frequencies from the DC power. In this embodiment, as shown in FIG. 11, the DC / DC inverter circuit 57 generates three positive / negative pulse signals. The three positive / negative pulse signals include a first positive / negative pulse signal having a first frequency f1, a second positive / negative pulse signal having a second frequency f2, and a third positive / negative pulse signal having a third frequency f3.

[0159] When the DC / DC inverter circuit 57 is connected to the second positive line 77 via the selector 53, it applies the third positive / negative pulse signal, the second positive / negative pulse signal, and the first positive / negative pulse signal in that order to the battery cell 31. In this embodiment, the DC / DC inverter circuit 57 corresponds to an example of a determination power supply generating unit of the present disclosure.

[0160] <2-2. Processing> <2-2-1. First example of abnormality determination processing> A first example of the abnormality determination process executed by the battery MCU 33 and the charger MCU 54 in S20 and S140 will be described with reference to FIG.

[0161] In S305 and S315, the charger MCU 54 executes the same processes as in S105 and S115. In S325, the charger MCU 54 switches the connection target of the selector 53 from the switching power supply circuit 51 to the DC / DC inverter circuit 57. As a result, the DC / DC inverter circuit 57 is connected to the second positive electrode line 77.

[0162] In S335, the charger MCU 54 commands the DC / DC inverter circuit 57 to output the third positive / negative pulse signal, the second positive / negative pulse signal, and the first positive / negative pulse signal in that order. In S345 and S355, the charger MCU 54 executes the same processes as in S145 and S155.

[0163] In S450 to S520, the battery MCU 33 executes the same processes as in S160 to S230. In S530, the battery MCU 33 performs a Fourier transform on the measured battery voltage value and battery current value at each frequency. The battery MCU 33 removes the second or higher order components of the Fourier transformed battery voltage value and battery current value, and leaves only the first order components.

[0164] In S540, the battery MCU 33 calculates the impedance Z(fk) from the Fourier-transformed battery voltage value and battery current value at each frequency, as shown in Fig. 11. That is, the battery MCU 33 calculates the impedance Z(f1), impedance Z(f2), and impedance Z(f3).

[0165] In S550 to S580, the battery MCU 33 executes the same processes as in S300 and S260 to S280.

[0166] <2-2-2. Second example of abnormality determination processing> A second example of the abnormality determination process executed by the battery MCU 33 and the charger MCU 54 in S20 and S140 will be described with reference to FIG.

[0167] The charger MCU 54 executes the same process as the first example of the abnormality determination process shown in FIG. The battery MCU 33 executes the processes of S350 and S360 instead of the processes of S530 to S560 of the first example of the abnormality determination process shown in FIG. 10, and executes the same processes as the first example of the abnormality determination process shown in FIG. 10 except for the processes of S530 to S560.

[0168] In S350, the battery MCU 33 calculates the impedance Z(fk) at each frequency from the waveforms of the battery voltage value and the battery current value, as shown in FIG. 13. That is, the battery MCU 33 calculates the impedance Z(fk) at each frequency from the ratio of the amplitude of the battery voltage value to the amplitude of the battery current value. Then, the battery MCU 33 sets the impedance Z(f2) as the negative electrode impedance Z1 and the impedance Z(f3) as the positive electrode impedance Z2. The negative electrode impedance Z1 includes a negative electrode resistance value R1 and a phase θ1, and the positive electrode impedance Z2 includes a positive electrode resistance value R2 and a phase θ2. In the second example of the abnormality determination process according to this embodiment, the negative electrode impedance Z1 corresponds to an example of the first impedance of the present disclosure, and the positive electrode impedance Z2 corresponds to an example of the second impedance of the present disclosure. In addition, in the second example of the abnormality determination process according to this embodiment, the negative electrode impedance Z1 corresponds to an example of the deterioration parameter of the negative electrode of the present disclosure, and the positive electrode impedance Z2 corresponds to an example of the deterioration parameter of the positive electrode of the present disclosure.

[0169] In S360, the battery MCU 33 compares the negative electrode impedance Z1 with the positive electrode impedance Z2 instead of the negative electrode resistance value R1 and the positive electrode resistance value R2, and determines whether the comparison result is within the normal range. The negative electrode impedance Z1 and the positive electrode impedance Z2 include a phase component. Therefore, the abnormal deterioration determination based on the comparison of the negative electrode impedance Z with the positive electrode impedance Z2 is less accurate than the abnormal deterioration determination based on the comparison of the negative electrode resistance value R1 with the positive electrode resistance value R2. However, the calculation of the negative electrode impedance Z1 and the positive electrode impedance Z2 is easier than the calculation of the negative electrode resistance value R1 and the positive electrode resistance value R2, and the processing load is significantly reduced.

[0170] <2-3.Effects> According to the second embodiment described above in detail, in addition to the effects (1) to (6) and (8) to (10) of the first embodiment described above, the following effects are also obtained.

[0171] (11) By alternately applying a positive pulse signal and a negative pulse signal to the battery cell 31, the charge amount of the battery cell 31 can be maintained constant, while the processing load for calculating the negative electrode resistance value R1 and the positive electrode resistance value R2 can be reduced compared to the case where an AC signal is applied to the battery cell 31.

[0172] (12) The battery MCU 33 can significantly reduce the processing load by using the negative electrode impedance Z1 and the positive electrode impedance Z2 instead of the negative electrode resistance value R1 and the positive electrode resistance value R2.

[0173] Third embodiment <3-1. Differences from the second embodiment> The third embodiment has a basic configuration similar to that of the second embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the second embodiment indicate the same configurations, and the preceding description will be referred to.

[0174] The power supply system 1B according to the second embodiment described above includes a battery pack 10A and a charger 50B. In contrast, a power supply system 1C according to a third embodiment includes a battery pack 10A and a charger 50C, and differs from the first embodiment in that it executes the abnormality determination process shown in Fig. 15 instead of the abnormality determination process shown in Fig. 10 or 12.

[0175] The configuration of the charger 50C will be described with reference to Fig. 14. The basic configuration of the charger 50C is similar to that of the charger 50B. The charger 50C differs from the charger 50B in that the charger 50C does not include the selector 53 and the DC / DC inverter circuit 57.

[0176] In this embodiment, the switching power supply circuit 51 receives a command from the charger MCU 54 and generates a positive pulse signal of a commanded frequency from the input AC power. One positive pulse signal includes a plurality of consecutive positive pulses. In detail, the switching power supply circuit 51 generates two or more positive pulse signals having different frequencies from the AC power. In this embodiment, as shown in FIG. 16, the switching power supply circuit 51 generates three positive pulse signals. The three positive pulse signals include a first positive pulse signal having a first frequency f1, a second positive pulse signal having a second frequency f2, and a third positive pulse signal having a third frequency f3. In this embodiment, the switching power supply circuit 51 corresponds to an example of a determination power supply generating unit of the present disclosure.

[0177] <3-2. Abnormality Judgment Processing> The abnormality determination processing executed by the battery MCU 33 and the charger MCU 54 in S20 and S140 will be described with reference to FIG.

[0178] In S405 and S415, the charger MCU 54 executes the same processes as in S305 and S315. In S425, the charger MCU 54 instructs the switching power supply circuit 51 to output the third positive pulse signal, the second positive pulse signal, and the first positive pulse signal in that order, as shown in FIG.

[0179] In S435, the charger MCU 54 executes the same process as in S355. In S600 to S710, the battery MCU 33 executes the same processes as in S450 to S520, S350 to S360, and S570 to S580.

[0180] <3-3.Effects> According to the third embodiment described above in detail, in addition to the effects (1) to (6), (8) to (10) of the first embodiment and the effect (12) of the second embodiment, the following effect is also obtained.

[0181] (13) By applying a positive pulse signal to the battery cell 31 instead of an AC signal and a positive / negative pulse signal, the configuration of the charger 50C can be made simpler than the chargers 50A and 50B. Furthermore, the processing load for calculating the negative electrode impedance Z1 and the positive electrode impedance Z2 can be reduced compared to the case where a positive / negative pulse signal is applied to the battery cell 31.

[0182] (Fourth embodiment) <4-1. Differences from the first to third embodiments> The fourth embodiment has the same basic configuration as the first to third embodiments, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0183] The battery MCU 33 and the charger MCU 54 according to the fourth embodiment differ from those of the first to third embodiments in that they execute a charge control process shown in FIG. 17 instead of the charge control process shown in FIG.

[0184] <4-2. Charging control process> A charging control process executed by the battery MCU 33 and the charger MCU 54 according to the fourth embodiment will be described with reference to Fig. 17. When the battery MCU 33 detects that the battery pack 10A is connected to the chargers 50A, 50B, and 50C, the battery MCU 33 starts this process and executes this process repeatedly at a predetermined cycle. When the charger MCU 54 detects that the chargers 50A, 50B, and 50C are connected to the battery pack 10A, the battery MCU 33 starts this process and executes this process repeatedly at a predetermined cycle.

[0185] In S505, S710, S720, S515 to S565, and S860, the charger MCU 54 executes the same processes as in S5, S10, S20, S15 to S65, and S140.

[0186] In S710 and S720, the battery MCU 33 executes the same processes as in S10 and S20. In S730, the battery MCU 33 determines whether the abnormal deterioration flag is on. If the battery MCU 33 determines that the abnormal deterioration flag is on (S730: YES), the battery MCU 33 proceeds to processing of S740, and if the battery MCU 33 determines that the abnormal deterioration flag is off (S730: NO), the battery MCU 33 proceeds to processing of S750.

[0187] In S740, the battery MCU 33 sets charging not permitted and ends this process. That is, the battery MCU 33 prohibits charging of the battery cell 31 when the battery cell 31 is in an abnormally deteriorated state.

[0188] In S750 to S860, the battery MCU 33 executes the same processes as in S30 to S140. In S720 and S860, the battery MCU 33 and the charger MCU 54 execute either the first and second examples of the abnormality determination processing according to the first embodiment, the first and second examples of the abnormality determination processing according to the second embodiment, or the abnormality determination processing according to the third embodiment.

[0189] <4-3.Effects> According to the fourth embodiment described above in detail, in addition to the effects (1) to (13) of the first to third embodiments described above, the following effect is further achieved.

[0190] (14) When it is determined that the battery cell 31 is in an abnormally deteriorated state, the battery MCU 33 suppresses charging of the battery cell 31. This makes it possible to protect the battery cell 31.

[0191] Fifth embodiment <5-1. Differences from the first to third embodiments> The fifth embodiment has the same basic configuration as the first to third embodiments, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0192] The battery MCU 33 and the charger MCU 54 according to the fifth embodiment differ from those of the first to third embodiments in that they execute a charge control process shown in FIG. 18 instead of the charge control process shown in FIG.

[0193] <5-2. Charging control processing> A charging control process executed by the battery MCU 33 and the charger MCU 54 according to the fifth embodiment will be described with reference to Fig. 18. When the battery MCU 33 detects that the battery pack 10A is connected to the chargers 50A, 50B, and 50C, the battery MCU 33 starts this process and executes this process repeatedly at a predetermined cycle. When the charger MCU 54 detects that the chargers 50A, 50B, and 50C are connected to the battery pack 10A, the battery MCU 33 starts this process and executes this process repeatedly at a predetermined cycle.

[0194] In S605, S900, S910, S615 to S665, and S1060, the charger MCU 54 executes the same processes as in S5, S10, S20, S15 to S65, and S140.

[0195] In S900 and S910, the battery MCU 33 executes the same processes as in S10 and S20. In S920, the battery MCU 33 determines whether the abnormal degradation flag is on. If the battery MCU 33 determines that the abnormal degradation flag is on (S910: YES), the battery MCU 33 proceeds to processing of S940, and if the battery MCU 33 determines that the abnormal degradation flag is off (S910: NO), the battery MCU 33 proceeds to processing of S930.

[0196] In S930, the battery MCU 33 sets T11 to the low temperature standby temperature. In S940, the battery MCU 33 sets the low temperature standby temperature to T12. T12 is a value greater than T11. That is, when the battery cell 31 is in an abnormally deteriorated state, the battery MCU 33 changes the control of the battery cell 31 and makes the conditions for allowing charging of the battery cell 31 stricter.

[0197] In S950 to S1060, the battery MCU 33 executes the same processes as in S30 to S140. In S900 and S1060, the battery MCU 33 and the charger MCU 54 execute either the first and second examples of the abnormality determination processing according to the first embodiment, the first and second examples of the abnormality determination processing according to the second embodiment, or the abnormality determination processing according to the third embodiment.

[0198] <5-3.Effects> According to the fifth embodiment described above in detail, in addition to the effects (1) to (13) of the first to third embodiments described above, the following effect is further achieved.

[0199] (15) When it is determined that the battery cell 31 is in an abnormally deteriorated state and the battery temperature is equal to or lower than the low-temperature standby temperature, the battery MCU 33 suppresses charging of the battery cell 31. This makes it possible to protect the battery cell 31.

[0200] (16) When it is determined that the battery cell 31 is in an abnormally deteriorated state, the battery MCU 33 increases the low-temperature standby temperature. This makes it possible to protect the battery cell 31.

[0201] Sixth embodiment <6-1. Differences from the first embodiment> The sixth embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

[0202] The power supply system 1A according to the first embodiment described above includes a battery pack 10A and a charger 50A. In contrast, a power supply system 1D according to the sixth embodiment differs from the first embodiment in that it includes a battery pack 10B and a charger 50D.

[0203] As shown in FIG. 19, the basic configuration of the battery pack 10B is similar to that of the battery pack 10A. The battery pack 10B includes a first connection unit 20B instead of the first connection unit 20A. The first connection unit 20B includes a first monitoring terminal 24 in addition to the configuration of the first connection unit 20A. The first connection unit 20B also includes a fifth communication terminal 27 instead of the third communication terminal 26. The fifth communication terminal 27 is connected to a temperature measurement unit 36. The temperature measurement unit 36 ​​may or may not be connected to the battery MCU 33. Furthermore, the battery pack 10B does not include a current / voltage monitoring circuit 32. The first monitoring terminal 24 is connected to the battery cell 31.

[0204] The basic configuration of the charger 50D is similar to that of the charger 50A. The charger 50D includes a second connection section 60B instead of the second connection section 60A. The second connection section 60B includes a second monitoring terminal 64 in addition to the configuration of the second connection section 60A. The second connection section 60B also includes a sixth communication terminal 67 instead of the fourth communication terminal 66. The sixth communication terminal 67 is connected to the charger MCU 54. The sixth communication terminal 67 is also connected to the fifth communication terminal 27. The second monitoring terminal 64 is connected to the first monitoring terminal 24, and a battery voltage value is input thereto.

[0205] The charger 50D includes an AC generating circuit 58 instead of the DC / AC inverter circuit 52. The AC generating circuit 58 receives a command from the charger MCU 54 and generates a first AC signal, a second AC signal, and a third AC signal, or a first positive / negative pulse signal, a second positive / negative pulse signal, and a third positive / negative pulse signal from the DC power input from the switching power supply circuit 51.

[0206] The charger 50D includes a current / voltage monitoring circuit 59 in addition to the configuration of the charger 50A. That is, in the sixth embodiment, the charger 50D includes a current / voltage monitoring circuit 59 instead of the battery pack 10B.

[0207] The current / voltage monitoring circuit 59 is connected to the battery cell 31 via the second monitoring terminal 64, and measures the battery voltage value. The current / voltage monitoring circuit 59 is also connected to the second shunt resistor 56, and measures the charging current value. The current / voltage monitoring circuit 59 is connected to the charger MCU 54, and outputs the measured battery voltage value and charging current value to the charger MCU 54.

[0208] The charger MCU 54 performs serial communication with the battery pack 10B via the second communication terminal 63 to acquire information about the battery pack 10B. The charger MCU 54 also acquires the battery temperature via the sixth communication terminal 67. The charger MCU 54 determines whether the battery cell 31 is in an abnormally deteriorated state based on the battery voltage value, the charging current value, the battery temperature, and information about the battery pack 10B, and executes charging control of the battery cell 31.

[0209] In this embodiment, the AC generating circuit 58 corresponds to an example of a determination power supply generating unit of the present disclosure, the current / voltage monitoring circuit 59 corresponds to an example of a measurement unit of the present disclosure, and the charger MCU 54 corresponds to an example of a determination unit of the present disclosure. That is, in this embodiment, the charger 50D includes a determination power supply generating unit, a measurement unit, and a determination unit.

[0210] Seventh embodiment <7-1. Differences from the first embodiment> The seventh embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0211] The power supply system 1A according to the first embodiment described above includes a battery pack 10A and a charger 50A. In contrast, a power supply system 1E according to the seventh embodiment differs from the first embodiment in that it includes a battery pack 10C and a charger 50E.

[0212] 20, the basic configuration of the battery pack 10C is similar to that of the battery pack 10A. The battery pack 10C includes a first connection part 20C instead of the first connection part 20A. The first connection part 20C includes a first power supply terminal 25 in addition to the configuration of the first connection part 20A. Moreover, the battery pack 10C includes a current / voltage monitoring and AC generating circuit 39 instead of the current / voltage monitoring circuit 32.

[0213] The basic configuration of the charger 50E is similar to that of the charger 50A. The charger 50E includes a second connection part 60C instead of the second connection part 60A. The second connection part 60C includes a second power supply terminal 65 in addition to the configuration of the second connection part 60A. The second power supply terminal 65 is connected to the switching power supply circuit 51 and to the first power supply terminal 25.

[0214] The current / voltage monitoring and AC generating circuit 39 measures the battery voltage value and the battery current value. Furthermore, the current / voltage monitoring and AC generating circuit 39 receives a command from the battery MCU 33 and generates a first AC signal, a second AC signal, and a third AC signal, or a first positive / negative pulse signal, a second positive / negative pulse signal, and a third positive / negative pulse signal from the DC power input from the switching power supply circuit 51 via the first power supply terminal 25. The current / voltage monitoring and AC generating circuit 39 applies the generated first AC signal, second AC signal, and third AC signal, or the generated first positive / negative pulse signal, second positive / negative pulse signal, and third positive / negative pulse signal to the battery cell 31 in order.

[0215] In this embodiment, the current / voltage monitoring and AC generating circuit 39 corresponds to an example of a determination power supply generating unit and an example of a measurement unit of the present disclosure, and the battery MCU 33 corresponds to an example of a determination unit of the present disclosure. That is, in this embodiment, the battery pack 10C includes a determination power supply generating unit, a measurement unit, and a determination unit.

[0216] (Other embodiments) Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0217] (a) In the above embodiment, the power supply units are the chargers 50A to 50E, but the power supply units are not limited to chargers. For example, the power supply units may be any device capable of supplying power to the battery packs 10A to 10C, such as a portable power supply or a battery checker.

[0218] (b) In the discharge control process of the first embodiment described above, when the battery MCU 33 determines that the battery cell 31 is in an abnormally deteriorated state, the battery MCU 33 tightens the conditions for permitting discharge from the battery cell 31, but discharge from the battery cell 31 may also be prohibited.

[0219] (c) In each of the above embodiments, the battery MCU 33 or the charger MCU 54 determines that the battery cell 31 is in an abnormally deteriorated state based on the result of comparing the negative electrode resistance value R1 and the positive electrode resistance value R2, or the result of comparing the negative electrode impedance Z1 and the positive electrode impedance Z2, but the present disclosure is not limited to this. The battery MCU 33 or the charger MCU 54 may determine that the battery cell 31 is in an abnormally deteriorated state based on the calculated negative electrode resistance value R1 and the calculated positive electrode resistance value R, and a first map. The first map, as shown in FIG. 3, indicates the correspondence between the negative electrode resistance value R1 and the positive electrode resistance value R2 and the presence or absence of abnormal deterioration, and is stored in advance in the memory of the battery MCU 33 or the charger MCU 54. Alternatively, the battery MCU 33 and the charger MCU 54 may determine that the battery cell 31 is in an abnormally deteriorated state based on the calculated negative electrode impedance Z1 and the calculated positive electrode impedance Z2, and a second map. The second map, as shown in FIG. 3, indicates the correspondence between the negative electrode impedance Z1 and the positive electrode impedance Z2 and the presence or absence of abnormal deterioration, and is stored in advance in the memory of the battery MCU 33 or the charger MCU .

[0220] (d) In the above embodiments, the negative electrode resistance value R1 or the negative electrode impedance Z1 is set as the deterioration parameter of the negative electrode, and the positive electrode resistance value R2 or the positive electrode impedance Z2 is set as the deterioration parameter of the positive electrode, but the present disclosure is not limited thereto. For example, the deterioration parameter of the negative electrode may be the difference between the initial value of the negative electrode resistance value R1 and the current negative electrode resistance value R1, or the difference between the initial value of the negative electrode impedance Z1 and the current negative electrode impedance Z1. Alternatively, the deterioration parameter of the negative electrode may be the ratio between the initial value of the negative electrode resistance value R1 and the current negative electrode resistance value R1, or the ratio between the initial value of the negative electrode impedance Z1 and the current negative electrode impedance Z1. Similarly, the deterioration parameter of the positive electrode may be the difference between the initial value of the positive electrode resistance value R2 and the current positive electrode resistance value R2, or the difference between the initial value of the positive electrode impedance Z2 and the current positive electrode impedance Z2. Alternatively, the deterioration parameter of the positive electrode may be the ratio between the initial value of the positive electrode resistance value R2 and the current positive electrode resistance value R2, or the ratio between the initial value of the positive electrode impedance Z2 and the current positive electrode impedance Z2.

[0221] (e) The signal applied to the battery cell 31 may be a single signal including multiple frequency components. For example, the signal applied to the battery cell 31 may be a swept sine signal. In this case, of the single signal, a portion having a first frequency component is regarded as a first component, and a portion having a second frequency component different from the first frequency component is regarded as a second component.

[0222] (f) The signal applied to the battery cell 31 may be one positive / negative pulse signal, one positive pulse signal, a multi-sine signal, or an M-sequence signal. In this case, a first frequency component obtained by Fourier transforming the signal applied to the battery cell 31 is regarded as the first component, and a second frequency component different from the first frequency component is regarded as the second component. Also, a bidirectional DC / DC converter may be used to generate the signal to be applied to the battery cell 31, and the generated signal may be applied to the battery cell 31.

[0223] (g) As an equivalent circuit of the battery cell 31, an inductor L or a constant phase element (CPE) may be used.

[0224] (h) Battery MCU 33 and / or charger MCU 54 may, instead of or in addition to a microcomputer, include a combination of various individual electronic components, an Application Specified Integrated Circuit (ASIC), an Application Specific Standard Product (ASSP), a programmable logic device such as a Field Programmable Gate Array (FPGA), or any combination thereof.

[0225] (i) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0226] 1A, 1B, 1C, 1D, 1E...power supply system, 10A, 10B, 10C...battery pack, 31...battery cell, 32...current / voltage monitoring circuit, 33...battery MCU, 35...first shunt resistor, 36...temperature measurement unit, 50A, 50B, 50C, 50D, 50E...charger, 51...switching power supply circuit, 52...DC / AC inverter circuit, 53...selector, 54...charger MCU, 56...second shunt resistor, 57...DC / DC inverter circuit, 59...current / voltage monitoring circuit.

Claims

1. A power supply system comprising: a battery pack including a battery cell; and a power supply unit configured to be connected to the battery pack, a determination power supply generating unit disposed in the battery pack or the power supply unit and configured to apply a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency to the battery cell; a first measurement unit disposed in the battery pack or the power supply unit and configured to measure a first current value flowing through the battery cell and a first voltage value of the battery cell corresponding to application of the first component to the battery cell, and a second current value flowing through the battery cell and a second voltage value of the battery cell corresponding to application of the second component to the battery cell; A determination unit disposed in the battery pack or the power supply unit, calculating a first impedance based on the first current value and the first voltage value measured by the first measurement unit; calculating a second impedance based on the second current value and the second voltage value measured by the first measurement unit; A determination unit configured to determine that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance. Power supply system.

2. the first component corresponds to a first signal; the second component corresponds to a second signal separate from the first signal; the determination power supply generating unit is configured to apply the first signal and the second signal to the battery cell in sequence; The power supply system of claim 1 .

3. The determination unit is configured to determine that the battery cell is abnormal based on a comparison result between the calculated first impedance and the calculated second impedance. The power supply system of claim 2 .

4. a storage unit that stores a map in which the first impedance and the second impedance correspond to an abnormality or a normality of the battery cell; The determination unit is configured to determine that the battery cell is abnormal based on the calculated first impedance, the calculated second impedance, and the map. The power supply system of claim 2 .

5. the first frequency is higher than the second frequency; The determination unit is configured to determine that the battery cell is abnormal when a first ratio, which is a ratio of the first impedance to the second impedance, is equal to or greater than a first threshold value. The power supply system of claim 3.

6. The determination unit is configured to determine that the battery cell is abnormal when the first ratio is less than the first threshold value and the first impedance is equal to or greater than a second threshold value.

6. The power supply system of claim 5.

7. the first frequency is higher than the second frequency; The determination unit is configured to determine that the battery cell is abnormal when a difference obtained by subtracting the first impedance from the second impedance is equal to or smaller than a third threshold value.

7. The power supply system according to claim 3, 5 or 6.

8. the determination unit is configured to determine that the battery cell is abnormal when the difference is greater than the third threshold and the first impedance is equal to or greater than a fourth threshold.

8. The power supply system of claim 7.

9. the first frequency is higher than the second frequency; The determination unit is configured to determine that the battery cell is abnormal when the first impedance is equal to or greater than a fifth threshold and the second impedance is equal to or less than a sixth threshold. The power supply system according to any one of claims 3 to 8.

10. Each of the first signal and the second signal is an AC signal. The power supply system according to any one of claims 2 to 9.

11. each of the first signal and the second signal is a positive pulse signal and a negative pulse signal that appear alternately; The power supply system according to any one of claims 2 to 9.

12. each of the first signal and the second signal is a continuous positive pulse signal; The power supply system according to any one of claims 2 to 9.

13. the determination power supply generating unit is further configured to apply, following the first signal and the second signal, a third signal having a third frequency higher than the second frequency to the battery cell; the first measurement unit is configured to measure a third current value flowing through the battery cell and a third voltage value of the battery cell corresponding to application of the third signal to the battery cell; The determination unit is calculating a first complex impedance at the first frequency from the first voltage value and the first current value; calculating a second complex impedance at the second frequency from the second voltage value and the second current value; calculating a third complex impedance at the third frequency from the third voltage value and the third current value; Calculating the first impedance by subtracting the real part of the first complex impedance from the real part of the second complex impedance; and calculating the second impedance by subtracting the real part of the second complex impedance from the real part of the third complex impedance. The power supply system according to any one of claims 5 to 9.

14. The determination unit is calculating the first impedance, which is a complex impedance at the first frequency, from the first voltage value and the first current value; and calculating the second impedance, which is a complex impedance at the second frequency, from the second voltage value and the second current value. The power supply system according to any one of claims 5 to 9.

15. the battery pack includes the first measurement unit and the determination unit, The power supply unit includes the determination power supply generating unit. The power supply system according to any one of claims 1 to 14.

16. The power supply unit includes the determination power supply generating unit, the first measuring unit, and the determination unit. The power supply system according to any one of claims 1 to 14.

17. the power supply unit being a charger configured to charge the battery cells; The power supply system according to any one of claims 1 to 16.

18. the determination power supply generating unit is configured to apply the signal to the battery cell when the battery pack is connected to the power supply unit and before the power supply unit starts charging the battery cell; 20. The power system of claim 17.

19. the determination power supply generating unit is configured to apply the signal to the battery cell after the battery pack is connected to the power supply unit and the power supply unit completes charging the battery cell; 19. A power supply system according to claim 17 or 18.

20. The battery pack is configured to change control of the battery cell when the determination unit determines that the battery cell is abnormal, or The charger is configured to change control of charging the battery cell when the determination unit determines that the battery cell is abnormal. The power supply system according to any one of claims 17 to 19.

21. When the determination unit determines that the battery cell is abnormal, the charger is configured to suppress charging of the battery cell. The power supply system according to any one of claims 17 to 19.

22. The battery pack further includes a second measurement unit configured to measure a temperature of the battery cell; The charger is configured to suppress charging of the battery cell when the determination unit determines that the battery cell is abnormal and the temperature measured by the second measurement unit is equal to or lower than a predetermined value. The power supply system according to any one of claims 17 to 21.

23. The battery pack is configured to prohibit discharge from the battery cell or change a condition for permitting discharge from the battery cell when the determination unit determines that the battery cell is abnormal. The power supply system according to any one of claims 17 to 22.

24. applying to a battery cell a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency; Measuring a first current value flowing through the battery cell and a first voltage value of the battery cell corresponding to application of the first component to the battery cell, and a second current value flowing through the battery cell and a second voltage value of the battery cell corresponding to application of the second component to the battery cell; calculating a first impedance based on the first current value and the first voltage value; calculating a second impedance based on the second current value and the second voltage value; determining that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance. A method for determining an abnormality in a battery cell.

25. A battery cell; a determination power supply generating unit configured to apply a signal including a first component having a first frequency and a second component having a second frequency different from the first frequency to the battery cell; a measurement unit configured to measure a first current value flowing into the battery cell and a first voltage value of the battery cell corresponding to application of the first component to the battery cell, and a second current value flowing into the battery cell and a second voltage value of the battery cell corresponding to application of the second component to the battery cell; A determination unit, calculating a first impedance based on the first current value and the first voltage value measured by the measurement unit; calculating a second impedance based on the second current value and the second voltage value measured by the measurement unit; A determination unit configured to determine that the battery cell is abnormal based on the calculated first impedance and the calculated second impedance. Battery pack.

26. A battery cell; a current measuring unit configured to measure and output a value of a current flowing from the battery cell; A voltage measurement unit configured to measure and output a voltage value of the battery cell; A control unit, Calculating a deterioration parameter of a positive electrode of the battery cell and a deterioration parameter of a negative electrode of the battery cell based on the input current value and the input voltage value; A control unit configured to perform charge / discharge control of the battery cell based on the calculated deterioration parameters of the positive electrode and the negative electrode. Battery pack.

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