Deterioration determination device and method

Abstract

A deterioration determining device according to one aspect of the present technology comprises: a plurality of secondary batteries connected in parallel with one another; a plurality of current measuring units which are allocated on a one-to-one basis to each secondary battery, and which are capable of measuring a current flowing through a current pathway of the allocated secondary battery; and a deterioration determining unit capable of identifying a secondary battery in which deterioration has occurred, among the plurality of secondary batteries, on the basis of a relationship between the signs of the currents measured by each current measuring unit.

Description

[Technical field]

[0001] The present technology relates to a deterioration determination device and a deterioration determination method. [Background technology]

[0002] In recent years, the use of secondary batteries has expanded to larger-scale devices such as electric vehicles and energy storage systems. The larger the device, the greater the damage caused by a fire, so the importance of developing technology to improve safety is increasing. In addition, it is important to properly understand abnormal behavior and deterioration of secondary batteries.

[0003] In Patent Document 1, in an assembled battery in which multiple secondary batteries are connected in parallel with each other, the difference in current flowing through each secondary battery is compared with a threshold value to determine whether any of the secondary batteries included in the assembled battery has deteriorated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-46334 A Summary of the Invention

[0005] However, there is a problem in Patent Document 1 in that it is not possible to identify which secondary battery has deteriorated. It is desirable to provide a deterioration determination device and a deterioration determination method that are capable of identifying a deteriorated secondary battery in a battery pack in which multiple secondary batteries are connected in parallel with each other.

[0006] A deterioration determination device relating to a first aspect of the present technology includes a plurality of secondary batteries connected in parallel with each other, a plurality of current measurement units each assigned to each secondary battery and capable of measuring a current flowing in a current path of the assigned secondary battery, and a deterioration determination unit capable of identifying a secondary battery among the plurality of secondary batteries that is experiencing deterioration based on the relationship between the signs of the currents measured by each current measurement unit.

[0007] A degradation determination method according to a second aspect of the present technology includes the following steps. A power supply device includes a plurality of secondary batteries connected in parallel with each other, and a plurality of current measuring units each assigned to each secondary battery to measure a current flowing through a current path of the assigned secondary battery, and identifies a secondary battery that is degraded among the plurality of secondary batteries based on a relationship between the signs of currents measured by the current measuring units.

[0008] According to the deterioration determination device relating to a first aspect of the present technology and the deterioration determination method relating to a second aspect of the present technology, a secondary battery that has deteriorated is identified among multiple secondary batteries connected in parallel with each other based on the relationship between the signs of currents measured by multiple current measuring units assigned one to each secondary battery, so that it is possible to identify a secondary battery that has deteriorated in a battery pack in which multiple secondary batteries are connected in parallel with each other.

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

[0010] [Figure 1] FIG. 1 is a diagram illustrating an example of functional blocks of an electronic device according to an embodiment of the present technology. [Diagram 2] FIG. 2 is a diagram showing a modified example of the secondary battery of FIG. [Diagram 3] FIG. 3 is a diagram showing a modified example of the secondary battery of FIG. [Figure 4] FIG. 4 is a diagram showing an example of voltage and current waveforms of a secondary battery that is not degraded. [Diagram 5] FIG. 5 is a diagram showing an example of voltage and current waveforms of a secondary battery that has not deteriorated and a secondary battery that has slightly deteriorated. [Figure 6]FIG. 6 is a diagram showing an example of voltage and current waveforms of a secondary battery that has not deteriorated and a secondary battery that has undergone significant deterioration. [Figure 7] FIG. 7 is a diagram showing an example of a deterioration determination procedure in the electronic device of FIG. [Figure 8] FIG. 8 is a diagram showing a modified example of the functional blocks of the electronic device of FIG. [Figure 9] FIG. 9 is a diagram showing a modified example of the functional blocks of the electronic device of FIG. [Figure 10] FIG. 10 is a diagram showing a modified example of the functional blocks of the electronic device of FIG. [Figure 11] FIG. 11 is a diagram showing a state in which a charging unit is connected to the secondary battery pack of FIG. [Figure 12] FIG. 12 is a diagram showing a state in which a charging unit is connected to the secondary battery pack of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0012] <1. Embodiment> [composition] A configuration of an electronic device 100 according to an embodiment of the present technology will be described. The electronic device 100 is equipped with a secondary battery pack 110 having a function of determining a deterioration state of a secondary battery. For example, as shown in FIG. 1, the electronic device 100 includes the secondary battery pack 110 and a load 120. A charging unit 200 that charges the secondary battery pack 110 is connected to the electronic device 100.

[0013] The load 120 is a device that performs various functions in the electronic device 100. The load 120 is provided with, for example, a control unit 121 (for example, an MCU (Micro Controller Unit)) that controls the device. The control unit 121 controls the load 120 based on, for example, a signal (for example, output data on the deterioration determination result) input from a deterioration determination unit 113 described later, and displays the deterioration determination result on a display unit (not shown). A secondary battery pack 110 that supplies power to the load 120 is connected to the load 120. The load 120 and the secondary battery pack 110 are electrically connected by wiring. A charging unit 200 that charges the secondary battery pack 110 is connected to the secondary battery pack 110. The secondary battery pack 110 and the charging unit 200 are electrically connected by wiring.

[0014] The secondary battery pack 110 has a secondary battery 111. The secondary battery 111 provided in the secondary battery pack 110 is an assembled type battery including a plurality of secondary batteries B1, B2, ... Bn connected in parallel to each other. Each of the secondary batteries B1, B2, ... Bn is, for example, a lithium ion battery. In the secondary battery 111, a plurality of secondary battery modules 111a may be provided in which the plurality of secondary batteries B1, B2, ... Bn are connected in parallel to each other. For example, as shown in FIG. 2, the plurality of secondary battery modules 111a may be connected in series to each other, or, for example, as shown in FIG. 3, the plurality of secondary battery modules 111a may be connected in parallel to each other.

[0015] The secondary battery 111 further includes a plurality of sensors S1, S2, ..., Sn (current measuring units). The plurality of sensors S1, S2, ..., Sn are assigned to each secondary battery one by one. The sensor S1 measures the current flowing through the current path of the secondary battery B1. The sensor S1 is connected in series with the secondary battery B1. The sensor S1 is configured to include, for example, a resistor connected in series with the secondary battery B1 and a comparator that detects the voltage difference between the voltages at both ends of the resistor. The sensor S2 measures the current flowing through the current path of the secondary battery B2. The sensor S2 is connected in series with the secondary battery B2. The sensor S2 is configured to include, for example, a resistor connected in series with the secondary battery B2 and a comparator that detects the voltage difference between the voltages at both ends of the resistor. The sensor Sn measures the current flowing through the current path of the secondary battery Bn. The sensor Sn is connected in series with the secondary battery Bn. The sensor Sn includes, for example, a resistor connected in series with the secondary battery Bn, and a comparator that detects the voltage difference between both ends of the resistor.

[0016] The secondary battery pack 110 further includes a current code detection unit 112 and a deterioration determination unit 113 .

[0017] The current sign detection unit 112 detects the sign of the current measured by each sensor S1, S2, ... Sn. When the output signal of each sensor S1, S2, ... Sn is a signal with a positive sign, this means, for example, that the current is flowing in a direction to charge the secondary batteries B1, B2, ... Bn. When the output signal of each sensor S1, S2, ... Sn is a signal with a negative sign, this means, for example, that the current is flowing in a direction to discharge the secondary batteries B1, B2, ... Bn.

[0018] The deterioration determination unit 113 identifies a secondary battery B1, B2, ... Bn that is degraded based on the relationship between the signs of the currents measured by the sensors S1, S2, ... Sn. The deterioration determination unit 113 determines that the secondary battery Bi is degraded when the sign of the current of a certain secondary battery Bi (i is any number from 1 to n) among the secondary batteries B1, B2, ... Bn is different from the sign of the current of one or more secondary batteries Bk (k is one or more numbers from 1 to n and different from i) different from the secondary battery Bi. The deterioration determination unit 113 outputs the determination result to the control unit 121.

[0019] 2, when multiple secondary battery modules 111a are connected in series with each other, the deterioration determination unit 113 identifies a deteriorated secondary battery for each parallel connection block 114 (secondary battery module 111a). Also, when multiple secondary battery modules 111a are connected in series with each other and further in parallel with each other as shown in FIG. 3, the deterioration determination unit 113 identifies a deteriorated secondary battery for each smallest parallel connection block (secondary battery module 111a).

[0020] Next, a transient response of the output current of the secondary battery, which is the basis for the determination in degradation determining unit 113, will be described.

[0021] (Preparation of the sample lithium-ion battery) Five commercially available lithium-ion batteries US18650FTC1 (rated capacity 1.05Ah) whose main positive electrode active material is lithium iron phosphate (LiFePO4, LFP) and whose main negative electrode active material is graphite were prepared. All of these were from the same manufacturing lot. For two of these batteries, first, a constant current discharge was performed at a current value equivalent to a 0.2 hour rate until the voltage fell below 2.0V (the rated capacity is 1.05Ah, and the current value It at the 1 hour rate is 1.05A, so the current value I at the 0.2 hour rate is 0.2It = 210mA). Then, immediately, CCCV charging was performed at a set current of 1.05A (=1It) and a set voltage of 3.6V (a two-step charging in which constant current charging at a set current value is performed until the set voltage is reached, and constant voltage charging is performed when the set voltage is reached), and this was stopped 2.5h after the start of charging. While maintaining the two lithium-ion batteries in a fully charged state, one each was placed in a thermostatic chamber set to two different temperatures, 50°C and 90°C, and left there for 25 days to allow them to deteriorate.

[0022] (Building a battery pack) The following three types of battery packs, A, B, and C, were prepared. Battery A is made up of three lithium-ion batteries connected in parallel that have not undergone the above-mentioned deterioration process. Battery B is made up of two lithium-ion batteries that have not undergone the above-mentioned deterioration process and a low-deterioration lithium-ion battery that has undergone the above-mentioned deterioration process and been stored at 50°C, connected in parallel. Battery C is made by connecting in parallel two lithium-ion batteries that have not undergone the above-mentioned deterioration process and a low-deterioration lithium-ion battery that has undergone the above-mentioned deterioration process and been stored at 90°C.

[0023] In each battery pack, one current sensor was installed per lithium-ion battery, allowing the current flowing through each lithium-ion battery to be measured individually.

[0024] The battery packs A, B, and C were placed in a thermostatic chamber at 23° C. and CCCV charging was performed at a set current of 3.15 A (= 1 It) and a set voltage of 3.6 V. CCCV charging was performed using the charging unit 200. This CCCV charging was stopped when the current value during constant voltage charging fell below 315 mA (= 0.1 It). The current of each lithium-ion battery after CCCV charging was completed was measured using a current sensor.

[0025] Figure 4 shows the voltage and current changes after the completion of CCCV charging of battery pack A. The current flowing through the three lithium-ion batteries in battery pack A had a waveform of either current Ia or Ib. In other words, the current flowing through the three lithium-ion batteries in battery pack A remained almost constant at zero. Note that in Figure 4, neither current Ia nor Ib is strictly zero, but this is due to measurement variations in the current sensor.

[0026] Figure 5 shows the voltage and current changes after CCCV charging of battery pack B is completed. The current flowing through the less-degraded lithium-ion battery in battery pack B has a waveform of current Ic, while the current flowing through the two normal lithium-ion batteries in battery pack B has a waveform of current Id. In other words, after CCCV charging is completed, charging current continues to flow through the less-degraded lithium-ion battery, while charging current continues to flow through the two normal lithium-ion batteries after CCCV charging is completed. This is thought to be because the overvoltage during charging of the less-degraded lithium-ion battery was high, causing the voltage of the less-degraded lithium-ion battery to drop after charging was completed.

[0027] Figure 6 shows the voltage and current changes after CCCV charging of battery pack C is completed. The current flowing through the highly deteriorated lithium-ion battery in battery pack C has a waveform of current Ie, while the current flowing through the two normal lithium-ion batteries in battery pack C has a waveform of current If. In other words, after CCCV charging is completed, a charging current flows through the highly deteriorated lithium-ion battery for only about three seconds, but after about three seconds, the sign of the current is reversed and a discharging current flows. On the other hand, after CCCV charging is completed, a discharging current flows through the two normal lithium-ion batteries for only about three seconds, but after about three seconds, the sign of the current is reversed and a charging current flows.

[0028] This is thought to be because the overvoltage during charging of the highly degraded lithium-ion battery was high, and although the voltage of the highly degraded lithium-ion battery dropped once after CCCV charging was completed, the current direction between the normal lithium-ion battery and the highly degraded lithium-ion battery was reversed due to one of the following reasons. Reason 1: The time constants of bulk resistance, charge transfer resistance, and diffusion resistance are all different. Reason 2: The SoC dependence of internal resistance is different Reason 3: The relationship between the internal resistance during charging and the internal resistance during discharging is different.

[0029] In view of the above, the deterioration determination unit 113 determines that the degree of deterioration of the secondary battery Bi is low when the sign of the current of the secondary battery Bi maintains the sign of the charging direction of the secondary battery Bi and the sign of the current of one or more secondary batteries Bk maintains the sign of the discharging direction of the one or more secondary batteries Bk during a predetermined period exceeding several seconds (e.g., 3 seconds) after the charging of the multiple secondary batteries B1, B2, ..., Bn is completed. Also, the deterioration determination unit 113 determines that the degree of deterioration of the secondary battery Bi is high when the sign of the current of the secondary battery Bi changes from the sign of the charging direction of the secondary battery Bi to the sign of the discharging direction of the secondary battery Bi and the sign of the current of one or more secondary batteries Bk changes from the sign of the discharging direction of the one or more secondary batteries Bk to the sign of the charging direction of the one or more secondary batteries Bk during a predetermined period exceeding several seconds (e.g., 3 seconds) after the charging of the multiple secondary batteries B1, B2, ..., Bn is completed. Here, high deterioration means that the degree of deterioration is higher than that of the above-mentioned low deterioration secondary battery Bi.

[0030] FIG. 7 shows an example of a deterioration determination procedure in the electronic device 100. First, the charging unit 200 starts charging the secondary battery pack 110 (step S101). Then, each sensor S1, S2, ... Sn starts measuring the current flowing through the current path of the corresponding secondary battery B1, B2, ... Bn (step S102). The charging unit 200 determines whether charging of the secondary battery pack 110 is complete or not, and as a result, if charging is not yet complete (step S103; N), charging continues. On the other hand, if charging is complete (step S103; Y), the charging unit 200 stops charging (step S104). At this time, there is no current flowing into or out of the secondary battery 11, and if a secondary battery outputs a discharge current, the current flows into a secondary battery other than the secondary battery.

[0031] Each sensor S1, S2, ... Sn judges whether a predetermined period of time exceeding several seconds (e.g., 3 seconds) has elapsed, and if the predetermined period has not yet elapsed (step S105; N), it continues to measure the current. On the other hand, if the predetermined period has elapsed (step S105; Y), each sensor S1, S2, ... Sn stops measuring the current (step S106).

[0032] Next, the current sign detection unit 112 detects the sign of the current measured by each of the sensors S1, S2, ..., Sn (step S107). The deterioration determination unit 113 identifies a secondary battery that is degraded among the multiple secondary batteries B1, B2, ..., Bn based on the relationship between the signs of the current measured by each of the sensors S1, S2, ..., Sn (step S108). Specifically, the deterioration determination unit 113 determines that the degree of deterioration of the secondary battery Bi is low when the sign of the current of the secondary battery Bi maintains the sign of the charging direction of the secondary battery Bi and the sign of the current of one or more secondary batteries Bk maintains the sign of the discharging direction of the one or more secondary batteries Bk for a predetermined period of time exceeding several seconds (e.g., 3 seconds) after the charging of the multiple secondary batteries B1, B2, ..., Bn is completed. Furthermore, the deterioration determination unit 113 determines that the degree of deterioration of the secondary battery Bi is high if, during a predetermined period exceeding several seconds (e.g., 3 seconds) after the charging of the multiple secondary batteries B1, B2, ... Bn is completed, the sign of the current of the secondary battery Bi changes from the sign of the charging direction of the secondary battery Bi to the sign of the discharging direction of the secondary battery Bi and the sign of the current of one or more secondary batteries Bk changes from the sign of the discharging direction of the one or more secondary batteries Bk to the sign of the charging direction of the one or more secondary batteries Bk. In this manner, deterioration determination in the electronic device 100 is performed.

[0033] [effect] Next, the effects of the electronic device 100 will be described.

[0034] In recent years, the use of secondary batteries has expanded to larger-scale devices such as electric vehicles and energy storage systems. The larger the device, the greater the damage caused by a fire, so the importance of developing technology to improve safety is increasing. In addition, it is important to properly understand abnormal behavior and deterioration of secondary batteries during use.

[0035] In Patent Document 1, in an assembled battery in which multiple secondary batteries are connected in parallel, the difference in current flowing through each secondary battery is compared with a threshold value to determine whether any of the secondary batteries included in the assembled battery is degraded. However, Patent Document 1 has a problem in that it is not possible to identify which secondary battery is degraded. In addition, in Patent Document 1, the current value flowing through each secondary battery is determined independently based on whether it exceeds a threshold value, so if a pulse current with a very high peak value flows through the entire assembled battery, all the single batteries may be determined to be abnormal.

[0036] On the other hand, in this embodiment, a deteriorated secondary battery Bi is identified from among a plurality of secondary batteries B1, B2, ... Bn connected in parallel to each other based on the relationship between the signs of the currents measured by a plurality of sensors S1, S2, ... Sn, each assigned to each secondary battery. This makes it possible to identify a deteriorated secondary battery Bi in a battery pack in which a plurality of secondary batteries B1, B2, ... Bn are connected in parallel to each other.

[0037] In addition, in this embodiment, if the sign of the current of a certain secondary battery Bi among the multiple secondary batteries B1, B2, ..., Bn is different from the sign of the current of one or more secondary batteries Bk different from the secondary battery Bi, it is determined that the secondary battery Bi has deteriorated. This allows the relationship between the currents flowing through the respective secondary batteries B1, B2, ..., Bn to be taken into consideration, making it possible to detect an abnormality more accurately. Even if a pulse current with an extremely high peak value flows through the entire battery pack, it is not determined that all the cells are abnormal.

[0038] In addition, in this embodiment, if the sign of the current of secondary battery Bi maintains the sign of the charging direction of secondary battery Bi and the sign of the current of one or more secondary batteries Bk maintains the sign of the discharging direction of the one or more secondary batteries Bk during a predetermined period of more than several seconds (e.g., 3 seconds) after the charging of the multiple secondary batteries B1, B2, ..., Bn is completed, the degree of deterioration of secondary battery Bi is determined to be low. Furthermore, in this embodiment, if the sign of the current of secondary battery Bi changes from the sign of the charging direction of secondary battery Bi to the sign of the discharging direction of secondary battery Bi and the sign of the current of one or more secondary batteries Bk changes from the sign of the discharging direction of the one or more secondary batteries Bk to the sign of the charging direction of the one or more secondary batteries Bk during a predetermined period of more than several seconds (e.g., 3 seconds) after the charging of the multiple secondary batteries B1, B2, ..., Bn is completed, the degree of deterioration of secondary battery Bi is determined to be high.

[0039] In this way, by detecting the change in current sign over time and determining whether or not there is an abnormality, it is possible to detect the phenomenon that is observed when a battery with a particularly high degree of abnormality has been mixed in, and to know that a serious abnormality has occurred.

[0040] <2. Modifications> Modifications of the electronic device 100 will be described below. In the following, components common to the above embodiment will be denoted by the same reference numerals as those in the above embodiment. Also, components different from the above embodiment will be mainly described, and descriptions of components common to the above embodiment will be omitted as appropriate.

[0041] [Variation A] In the above-described embodiment, the current code detection unit 112 and the deterioration determination unit 113 may be provided outside the secondary battery pack 110, for example, as shown in Fig. 8. In this case, the secondary battery pack 110 may have a sensor signal output unit 114 that outputs data (sensor signal) of the current measured by each of the sensors S1, S2, ... Sn to the current code detection unit 112. In this way, even when the current code detection unit 112 and the deterioration determination unit 113 are provided outside the secondary battery pack 110, the same effects as those of the above-described embodiment can be obtained.

[0042] [Variation B] In the above-described embodiment and modification A, for example, as shown in Fig. 9 and Fig. 10, a switch SW for connecting and disconnecting the positive and negative electrodes of the secondary battery 111 to the load 120 may be provided between the positive and negative electrodes of the secondary battery 111 and the load 120. The switch SW is configured to include, for example, a field effect transistor (FET).

[0043] The switch SW is on at least while the charging unit 200 is charging the secondary battery 111, and is off for a predetermined period of time that exceeds at least several seconds (e.g., 3 seconds) after the charging unit 200 finishes charging the secondary battery 111. While the switch SW is off, no current flows into or out of the secondary battery 11, and the secondary battery 11 is in an open circuit state. Therefore, if a certain secondary battery outputs a discharge current, that current flows into a secondary battery other than that secondary battery.

[0044] In this modification, a switch SW is provided between the positive and negative electrodes of the secondary battery 111 and the load 120. This ensures that the secondary battery 11 is in an open circuit state for a predetermined period of at least several seconds (e.g., 3 seconds) after charging of the secondary battery 111 by the charging unit 200 is completed. As a result, no current flows in or out of the secondary battery 111, and deterioration can be determined with high accuracy.

[0045] [Variation C] In the above embodiment, for example, as shown in Fig. 11, the load 120 may be removed from the secondary battery pack 110, and only the charging unit 200 may be connected to the secondary battery pack 110. In this case, the charging unit 200 has a charging circuit 210, a receiving unit 220, and a display unit 230, for example, as shown in Fig. 11.

[0046] The charging circuit 210 is a circuit that supplies a current for charging the secondary battery pack 110 to the secondary battery pack 110. The receiving unit 220 receives a signal (e.g., output data on the deterioration determination result) from the deterioration determination unit 113. The display unit 230 displays the deterioration determination result based on, for example, the signal received by the receiving unit 220 (e.g., output data on the deterioration determination result).

[0047] In this modification, the load 120 is removed from the secondary battery pack 110, and only the charging unit 200 is connected to the secondary battery pack 110. Even in this case, the same effects as those of the above embodiment can be obtained.

[0048] [Variation D] In the above modification A, for example, as shown in Fig. 12, the load 120 may be removed from the secondary battery pack 110, and only the charging unit 200 may be connected to the secondary battery pack 110. In this case, the charging unit 200 has, for example, a charging circuit 210, a receiving unit 220, a current code detection unit 112, a deterioration determination unit 113, and a display unit 230, as shown in Fig. 12.

[0049] The charging circuit 210 is a circuit that supplies a current for charging the secondary battery pack 110 to the secondary battery pack 110. The receiving unit 220 receives data (sensor signals) of the current measured by each sensor S1, S2, ... Sn from the sensor signal output unit 114. The current sign detection unit 112 detects the sign of the current measured by each sensor S1, S2, ... Sn based on the sensor signal received by the receiving unit 220. The deterioration determination unit 113 identifies a secondary battery that has deteriorated among the multiple secondary batteries B1, B2, ... Bn based on the relationship between the signs of the currents measured by each sensor S1, S2, ... Sn. The display unit 230 displays the deterioration determination result based on, for example, the signal received by the receiving unit 220 (for example, output data on the deterioration determination result).

[0050] In this modification, the load 120 is removed from the secondary battery pack 110, and only the charging unit 200 is connected to the secondary battery pack 110. Even in this case, the same effects as those of the above embodiment can be obtained.

[0051] The effects described in this specification are merely examples, and the effects of the present technology are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present technology.

[0052] The present technology can also be configured as follows. <1> A plurality of secondary batteries connected in parallel with each other; a plurality of current measurement units each assigned to each of the secondary batteries, each capable of measuring a current flowing through a current path of the assigned secondary battery; a degradation determination unit capable of identifying a secondary battery that is degraded among the plurality of secondary batteries based on a relationship between signs of currents measured by the current measurement units; Equipped with Deterioration determination device. <2> The deterioration determination unit is capable of determining that deterioration has occurred in a first secondary battery when the sign of a current of a first secondary battery among the plurality of secondary batteries is different from the sign of a current of one or more second secondary batteries different from the first secondary battery. <1> The deterioration determination device according to claim 1. <3> The deterioration determination unit is capable of determining that the degree of deterioration of the first secondary battery is low when the sign of the current of the first secondary battery maintains the sign of the charging direction of the first secondary battery and the sign of the current of the one or more second secondary batteries maintains the sign of the discharging direction of the one or more second secondary batteries for a predetermined period of time exceeding several seconds after charging of the multiple secondary batteries is completed. <2> The deterioration determination device according to claim 1. <4> The deterioration determination unit is capable of determining that the degree of deterioration of the first secondary battery is high when, during a predetermined period exceeding several seconds after charging of the multiple secondary batteries is completed, the sign of the current of the first secondary battery changes from the sign of the charging direction of the first secondary battery to the sign of the discharging direction of the first secondary battery, and the sign of the current of the one or more second secondary batteries changes from the sign of the discharging direction of the one or more second secondary batteries to the sign of the charging direction of the one or more second secondary batteries. <2> The deterioration determination device according to claim 1. <5> The power supply device includes a plurality of secondary batteries connected in parallel with each other, and a plurality of current measurement units each assigned to each of the secondary batteries to measure a current flowing through a current path of the assigned secondary battery, and identifies a secondary battery that is degraded among the plurality of secondary batteries based on a relationship between signs of currents measured by the current measurement units. Deterioration judgment method. <6> determining that a first secondary battery has deteriorated when a sign of a current of a first secondary battery among the plurality of secondary batteries is different from a sign of a current of one or more second secondary batteries different from the first secondary battery. <5> The deterioration determination method according to claim 1. <7> determining that the degree of deterioration of the first secondary battery is low when the sign of the current of the first secondary battery maintains the sign of the charging direction of the first secondary battery and the sign of the current of the one or more second secondary batteries maintains the sign of the discharging direction of the one or more second secondary batteries for a predetermined period of time exceeding several seconds after charging of the multiple secondary batteries is completed. <6> The deterioration determination method according to claim 1. <8> determining that the degree of degradation of the first secondary battery is high when, during a predetermined period exceeding several seconds after charging of the multiple secondary batteries is completed, the sign of the current of the first secondary battery changes from the sign of the charging direction of the first secondary battery to the sign of the discharging direction of the first secondary battery, and the sign of the current of the one or more second secondary batteries changes from the sign of the discharging direction of the one or more second secondary batteries to the sign of the charging direction of the one or more second secondary batteries. <6> The deterioration determination method according to claim 1.

[0053] The current code detection unit 112, the deterioration determination unit 113, the sensor signal output unit 114, the control unit 121, and the receiving unit 220 can be implemented by a circuit including at least one semiconductor integrated circuit, such as at least one processor (e.g., a central processing unit (CPU)), at least one application specific integrated circuit (ASIC), and / or at least one field programmable gate array (FPGA). The at least one processor can be configured to execute all or part of various functions in the current code detection unit 112, the deterioration determination unit 113, the sensor signal output unit 114, the control unit 121, and the receiving unit 220 by reading instructions from at least one non-transitory and tangible computer-readable medium. Such a medium can take various forms, including, but not limited to, various magnetic media such as hard disks, various optical media such as CDs or DVDs, and various semiconductor memories (i.e., semiconductor circuits) such as volatile or non-volatile memories. Volatile memories can include DRAM and SRAM. Non-volatile memories can include ROM and NVRAM. The ASIC is an integrated circuit (IC) specialized to execute all or part of the various functions of the current code detection unit 112, the deterioration determination unit 113, the sensor signal output unit 114, the control unit 121, and the receiving unit 220. The FPGA is an integrated circuit designed to be configurable after manufacture to execute all or part of the various functions of the current code detection unit 112, the deterioration determination unit 113, the sensor signal output unit 114, the control unit 121, and the receiving unit 220.

Claims

1. A plurality of secondary batteries connected in parallel with each other; a plurality of current measurement units each assigned to each of the secondary batteries, each capable of measuring a current flowing through a current path of the assigned secondary battery; a degradation determination unit capable of identifying a secondary battery that is degraded among the plurality of secondary batteries based on a relationship between signs of currents measured by the current measurement units; Equipped with the deterioration determination unit is capable of determining that deterioration has occurred in a first secondary battery among the plurality of secondary batteries when a sign of a current of a first secondary battery is different from a sign of a current of one or more second secondary batteries different from the first secondary battery, The deterioration determination unit is capable of determining that the degree of deterioration of the first secondary battery is high when, during a predetermined period exceeding several seconds after charging of the multiple secondary batteries is completed, the sign of the current of the first secondary battery changes from the sign of the charging direction of the first secondary battery to the sign of the discharging direction of the first secondary battery, and the sign of the current of the one or more second secondary batteries changes from the sign of the discharging direction of the one or more second secondary batteries to the sign of the charging direction of the one or more second secondary batteries. Deterioration determination device.

2. The deterioration determination unit is capable of determining that the degree of deterioration of the first secondary battery is low when the sign of the current of the first secondary battery maintains the sign of the charging direction of the first secondary battery and the sign of the current of the one or more second secondary batteries maintains the sign of the discharging direction of the one or more second secondary batteries for a predetermined period of time exceeding several seconds after charging of the multiple secondary batteries is completed. The deterioration determining device according to claim 1 .

3. a power supply device including a plurality of secondary batteries connected in parallel with each other and a plurality of current measuring units each assigned to each of the secondary batteries to measure a current flowing through a current path of the assigned secondary battery, the power supply device identifying a secondary battery that is degraded among the plurality of secondary batteries based on a relationship between signs of currents measured by each of the current measuring units; determining that a deterioration has occurred in a first secondary battery among the plurality of secondary batteries when a sign of a current of a first secondary battery is different from a sign of a current of one or more second secondary batteries different from the first secondary battery; determining that the degree of degradation of the first secondary battery is high when, during a predetermined period exceeding several seconds after charging of the multiple secondary batteries is completed, the sign of the current of the first secondary battery changes from the sign of the charging direction of the first secondary battery to the sign of the discharging direction of the first secondary battery, and the sign of the current of the one or more second secondary batteries changes from the sign of the discharging direction of the one or more second secondary batteries to the sign of the charging direction of the one or more second secondary batteries. Deterioration judgment method.

4. determining that the degree of degradation of the first secondary battery is low when the sign of the current of the first secondary battery maintains the sign of the charging direction of the first secondary battery and the sign of the current of the one or more second secondary batteries maintains the sign of the discharging direction of the one or more second secondary batteries for a predetermined period of time exceeding several seconds after charging of the multiple secondary batteries is completed. The deterioration determination method according to claim 3 .

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