JP6365820B2 - Secondary battery abnormality determination device - Google Patents

Description

  The present invention relates to an abnormality determination device for a secondary battery in which a current collector is enclosed in a battery case, and more particularly to an abnormality determination device for a secondary battery that determines the presence or absence of battery abnormality based on a short-circuit current.

  In recent years, many electric vehicles such as electric vehicles (BEV) and plug-in hybrid vehicles (PHEV) have been put into practical use. Such an electric vehicle is equipped with a secondary battery (high voltage battery) such as a lithium ion battery for supplying electric power to the traveling motor. This secondary battery includes, for example, a current collector formed of a laminate in which a positive electrode plate and a negative electrode plate are laminated via a separator, and is formed by enclosing the current collector in a case. .

  In the secondary battery having such a configuration, there is a possibility that a short circuit (internal short circuit) may occur in the current collector housed in the battery case due to, for example, foreign matter mixed in the battery case. Since the current collector of the secondary battery is enclosed in the battery case, the internal short circuit state cannot be directly detected.

  For this reason, conventionally, the amount of change in the voltage of the secondary battery during a predetermined time is measured, and the presence or absence of an internal short circuit, that is, the presence or absence of an abnormality in the secondary battery is determined based on the measurement result (for example, Patent Document 1).

JP 2010-153275 A

  As described in Patent Document 1, it is possible to determine the presence or absence of an internal short circuit from the amount of change in the battery voltage of the secondary battery, but it is difficult to say that it has been properly determined.

  The amount of change in battery voltage may vary greatly depending on the state of the secondary battery, for example, the charging rate of the secondary battery, the degree of deterioration of the secondary battery over time, and the like. For this reason, if the presence or absence of an internal short circuit, that is, the presence or absence of an abnormality of the secondary battery is determined according to the amount of change in the battery voltage, there is a possibility that it may be determined that there is an abnormality up to a normal range. That is, it is difficult to determine with high accuracy from the amount of change in the battery voltage to the short circuit state (the degree of internal short circuit).

  This invention is made | formed in view of such a situation, and it aims at providing the abnormality determination apparatus of the secondary battery which can determine the grade of an internal short circuit with high precision.

A first aspect of the present invention that solves the above problem is an abnormality determination device that determines an abnormality of a secondary battery configured by enclosing an electrode bundle including a positive electrode plate and a negative electrode plate in a case. Depending on the short-circuit current calculation means for calculating the short-circuit current of the secondary battery, the abnormality determination means for determining the presence or absence of abnormality of the secondary battery based on the calculation result of the short-circuit current calculation means, and the charging rate of the secondary battery Reference value setting means for setting a determination reference value, wherein the abnormality determination means determines that the secondary battery is abnormal when the short-circuit current is equal to or greater than the determination reference value. The secondary battery abnormality determination device.

According to a second aspect of the present invention, in the abnormality determination device for a secondary battery according to the first aspect, the reference value setting unit is configured to determine the determination criterion according to a temperature of the secondary battery together with a charge rate of the secondary battery. In the secondary battery abnormality determination device, the value is set.

According to a third aspect of the present invention, in the abnormality determination device for a secondary battery according to the first or second aspect, a current change for calculating a change in the short-circuit current within a predetermined period based on a calculation result of the short-circuit current calculation unit An abnormality determination device for a secondary battery, further comprising: calculation means; and estimation means for estimating when the short-circuit current reaches the determination reference value based on a calculation result of the current change calculation means. .

  According to the abnormality determination device for a secondary battery according to the present invention, it is possible to determine the presence or absence of an internal short circuit and to determine even a short circuit state (the degree of internal short circuit). Moreover, a continuous useable period can also be estimated by detecting the change of a short circuit current.

It is a disassembled perspective view which shows an example of the structure of a secondary battery. It is a longitudinal cross-sectional view which shows an example of the structure of a secondary battery. It is the schematic which shows the laminated structure of the electrode bundle with which a secondary battery is equipped. 1 is a block diagram illustrating an abnormality detection device for a secondary battery according to an embodiment of the present invention. It is a graph explaining the map which prescribes | regulates the relationship between battery capacity and battery voltage. It is a graph explaining the map which prescribes | regulates the relationship between SOC and a short circuit current. It is a graph which shows the relationship between SOC and a short circuit current. It is a graph which shows the relationship between SOC and a short circuit current, and a reference determination value. It is a graph which shows the relationship between elapsed days and a short circuit current (estimated value).

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
First, an example of the structure of the secondary battery will be briefly described. As shown in FIGS. 1 and 2, the secondary battery 10 is a sealed battery that is, for example, a lithium ion battery, and includes an electrode bundle (element) 20 including a positive electrode plate 21 and a negative electrode plate 22, and a current collector 30. 40 are accommodated in a battery case 50 together with a non-aqueous electrolyte (not shown). The upper part of the battery case 50 is sealed with a lid member 60. Although illustration is omitted, an insulating member that covers the inner surface of the battery case 50 is provided in the battery case 50 so that the battery case 50 is insulated from the electrode bundle 20 and the current collectors 30 and 40 accommodated therein. Is planned.

  One end side of the current collector 30 is connected to the positive electrode plate 21 of the electrode bundle 20, and the other end side of the current collector 30 is connected to the positive electrode terminal member 70 projecting outside from the through hole 61 provided in the lid member 60. Is connected. One end of a current collector 40 is connected to the negative electrode plate 22. The other end side of the current collector 40 is connected to a negative electrode terminal member 80 that protrudes to the outside from a through hole 61 provided in the lid member 60.

  Insulating sheet members 90 are respectively provided on the upper and lower surfaces of the lid member 60 so as to correspond to the openings of the through holes 61. The positive electrode terminal member 70 and the negative electrode terminal member 80 are insulated from the lid member 60 by the insulating sheet member 90.

  As shown in FIG. 3, the electrode bundle 20 is formed, for example, by laminating a positive electrode plate 21 and a negative electrode plate 22 made of metal foil with an offset lamination via a separator 23. The electrode bundle 20 according to the present embodiment is formed by winding a belt-like positive electrode plate 21 and a negative electrode plate 22 in a flat shape via a separator 23. The strip-like positive electrode plate 21 and negative electrode plate 22 are each coated with an active material at a portion where they overlap.

  Next, an abnormality determination device that determines abnormality such as the presence or absence of an internal short circuit of the secondary battery 10 having such a configuration will be described.

  In the secondary battery 10, for example, there is a possibility that an internal short circuit may occur due to foreign matters mixed in the battery case 50. The abnormality determination device according to the present invention executes determination of the presence or absence of an internal short circuit of the secondary battery 10 at a predetermined timing as abnormality determination of the secondary battery 10.

  In the abnormality determination device 100 according to the present embodiment, as will be described in detail below, a voltage change (decrease) amount per fixed time is measured, and based on a short-circuit current calculated from the voltage change amount, The presence or absence of an internal short circuit of the secondary battery 10 is determined. Thereby, the presence or absence of an internal short circuit of the secondary battery 10 can be determined, and the short circuit state (the degree of short circuit) can also be determined with relatively high accuracy.

  As shown in FIG. 4, the abnormality determination device 100 according to the present embodiment includes a voltage detection unit 110, a short-circuit current calculation unit 120, a reference value setting unit 130, and an abnormality determination unit 140 as a control unit. .

  The voltage detection unit 110 detects a voltage (hereinafter also referred to as a battery voltage) between the positive electrode terminal member 70 and the negative electrode terminal member 80 of the secondary battery 10. In the present embodiment, the short circuit current calculation unit 120 calculates the short circuit current value of the secondary battery 10 based on the battery voltage detected by the voltage detection unit 110. Here, the “short circuit current” refers to a current value generated due to an internal short circuit of the secondary battery 10.

  In calculating the “short circuit current”, first, the “total current” is calculated. The “total current” is a total value of “short circuit current” and current generated by other factors. First, the change amount ΔV1 of the battery voltage V1 (V) of the secondary battery 10 is converted into the change amount ΔAh1 of the battery capacity Ah1 (Ah). For example, based on a map that defines the relationship between the battery capacity Ah1 and the battery voltage V1 as shown in FIG. 5, the battery voltage change amount ΔV1 is converted into the battery capacity change amount ΔAh1.

  Here, the relationship between the battery capacity Ah <b> 1 and the battery voltage V <b> 1 varies depending on the deterioration state of the secondary battery 10. Specifically, when the secondary battery 10 is “degraded”, the maximum value Ah1m of the battery capacity tends to be smaller than when the secondary battery 10 is “degraded” (see FIG. 5). For this reason, the value ΔAh1 of the battery capacity change also changes depending on whether the secondary battery 10 is deteriorated. Therefore, the relationship between the battery capacity Ah1 and the battery voltage V1 is preferably defined by a plurality of deterioration states. Thereby, according to the deterioration state of the secondary battery 10, battery voltage change amount (DELTA) V1 can be appropriately converted into battery capacity change amount (DELTA) Ah1.

  In the example of FIG. 5, the relationship between the battery capacity Ah1 and the battery voltage V1 is defined in the case of “with deterioration” and the case of “without deterioration” of the secondary battery 10. Instead of “,” the relationship between the battery capacity Ah1 and the battery voltage V1 may be defined in a plurality of deterioration states having different degrees.

  As can be seen from the graph of FIG. 5, the amount of change ΔV1 in the battery voltage when the secondary battery 10 is left for a predetermined time t (h) from the fully charged state (4.1 (V) in this example) is Assuming that the secondary battery 10 is constant regardless of the deterioration state, the battery capacity change amount ΔAh1a in the case of “no deterioration” is larger than the battery capacity change amount ΔAh1b in the case of “with deterioration”. . That is, the change amount ΔAh1 of the battery capacity of the secondary battery 10 changes depending on the deterioration state of the secondary battery 10. Therefore, based on the graph (map) as shown in FIG. 5, the battery voltage change amount ΔAh1 is obtained by converting the battery voltage change amount ΔV1 into the battery capacity change amount ΔAh1 according to the deterioration state of the secondary battery 10. Can improve the accuracy.

The total current A1 (A) can be obtained by the following equation (1) from the battery capacity change amount ΔAh1 thus converted and the predetermined time t (h). As described above, as the accuracy of the battery capacity change amount ΔAh1 is improved, the accuracy of the total current A1 (A) is also improved.
A1 = ΔAh1 / t (1)

And short circuit current A2 is calculated | required by subtracting short circuitless current A3 from the total current A1 calculated in this way so that it may be represented by following formula (2).
A2 = A1-A3 (2)

  Here, the “current without short circuit” is, for example, a value of a current that flows due to self-discharge, consumption in a cell monitor unit (CMU), dark current, and the like, and is measured in advance. The short-circuitless current varies depending on the state of the secondary battery 10, for example, the charging rate (SOC), temperature, deterioration state, and the like. Therefore, in this embodiment, the abnormality determination device 100 holds a plurality of data (current without short circuit) in which the state of the secondary battery 10 is changed. For example, as shown in FIG. 6, in this embodiment, data defining the relationship between the SOC of the secondary battery 10 and the short-circuit current when the temperature is set to room temperature (25 ° C.), 0 ° C., and −30 ° C. I keep it as a map. The same data is held for the secondary battery 10 with “deteriorated”.

  The accuracy of the short circuit current can be improved by obtaining the current without a short circuit based on such data. As described above, the accuracy of the total current A1 (A) is also improved. Therefore, the accuracy of the short-circuit current A2 obtained by the above equation (2) is also greatly improved.

  Further, the short circuit current A <b> 2 varies greatly depending on the short circuit state (the degree of short circuit) of the secondary battery 10. For example, as shown in FIG. 7, a state where the degree of short circuit is small (short circuit: small), a state where the degree of short circuit is medium (short circuit: medium), a state where the degree of short circuit is large (short circuit: large), When the degree of short circuit is larger, the value of the total current A1 is larger. This tendency is the same even at different temperatures. Therefore, the abnormality determination device 100 according to the present embodiment determines whether there is an abnormality in the secondary battery 10 from the short-circuit current A2 according to the short-circuit state of the secondary battery 10.

  Here, the reference value setting unit 130 sets a determination reference value S1 that is a determination reference for the presence or absence of abnormality of the secondary battery 10. The reference value setting unit 130 according to the present embodiment sets the determination reference value S1 according to, for example, the charging rate (SOC) of the secondary battery 10, the temperature of the secondary battery 10, and the like.

  Then, the abnormality determination unit 140 determines whether there is an abnormality in the secondary battery 10 based on the short circuit current A2 calculated by the short circuit current calculation unit 120 in this way. Specifically, the abnormality determination unit 140 determines that there is an abnormality in the secondary battery 10 when the short-circuit current A2 is equal to or greater than the determination reference value S1 set by the reference value setting unit 130.

  For example, as shown in FIG. 8, when the determination reference value S1 is set to 0.08 (A), the SOC of the secondary battery 10 is “short: medium” and “short: small”. Regardless of this, since the short-circuit current A2 does not exceed the determination reference value S1, it is always determined that there is no abnormality. On the other hand, when the short circuit state of the secondary battery 10 is “short circuit: large”, the short circuit current A2 exceeds the determination reference value S1 when the SOC becomes 80% or more. Therefore, when the SOC is less than 80%, it is determined that there is no abnormality, and when the SOC is 80 or more, it is determined that there is an abnormality.

  As described above, it is possible to make a determination suitable for the state of the secondary battery 10 by determining whether or not the secondary battery 10 is abnormal based on the short-circuit current A2.

  The result determined by the abnormality determination unit 140 is displayed on, for example, the display device 150 provided in the abnormality determination device 100.

  Further, as described above, in the present embodiment, the presence / absence of abnormality of the secondary battery 10 is determined based on the short circuit current A2. However, in the abnormality determination device 100 of the present invention, for example, the short circuit current A2 for a predetermined period is used. By measuring this change, it is also possible to predict a period during which the short-circuit current reaches the determination reference value S1 based on the measurement result. That is, it is possible to predict a period until the abnormality determination device 100 determines that the secondary battery 10 is abnormal. For example, as shown in FIG. 9, by measuring the change in the short-circuit current A2 for a predetermined period of 30 days, the subsequent change in the short-circuit current A2 can be predicted as shown by the dotted line in the figure. The short-circuit current A2 does not necessarily change linearly, but a change in the short-circuit current A2 can be predicted by measuring the change in the short-circuit current A2 for a certain period (for example, about 30 days). . That is, it is possible to predict a period until the short-circuit current A2 reaches the determination reference value S1.

  For example, in the example shown in FIG. 9, when the short-circuit state of the secondary battery 10 is “short-circuit: A”, the period until the short-circuit current A2 reaches the determination reference value S1 can be predicted to be about 50 days. : "B" can be predicted to have a period of about 90 days until the short-circuit current A2 reaches the judgment reference value S1, and "Short-circuit: C" is the time until the short-circuit current A2 reaches the judgment reference value S1. The period can be estimated to be about 110 days.

  Thereby, it is possible to warn the user in advance of the occurrence of an abnormality in the secondary battery 10, and the user can perform a desired response such as repair with sufficient time.

  Note that it is difficult to measure the short-circuit current A2 of the secondary battery 10 under certain conditions. However, the measured value of the short-circuit current A2 can be appropriately corrected according to the temperature and the SOC with reference to, for example, the various maps described above. Therefore, the period until the short-circuit current A2 reaches the determination reference value S1 can be predicted relatively easily.

  As mentioned above, although embodiment of this invention was described, of course, this invention is not limited to the above-mentioned embodiment. The present invention can be modified as appropriate without departing from the spirit of the present invention.

  The abnormality determination device for the secondary battery described above is preferably used for abnormality determination of a secondary battery for a vehicle, for example, but the application of the secondary battery is not limited. The abnormality determination device for a secondary battery according to the present invention is also applicable to an abnormality determination of a secondary battery mounted on a device other than a vehicle, such as a home auxiliary power source, various AV devices, a personal computer, a mobile phone, and the like. In this case, the same effects as those of the above-described embodiment can be obtained.

DESCRIPTION OF SYMBOLS 10 Secondary battery 20 Electrode bundle 21 Positive electrode plate 22 Negative electrode plate 23 Separator 30,40 Current collector 50 Battery case 60 Lid member 70 Positive electrode terminal member 80 Negative electrode terminal member 90 Insulating sheet member 100 Abnormality determination apparatus

Claims (3)

An abnormality determination device for determining an abnormality of a secondary battery configured by enclosing an electrode bundle including a positive electrode plate and a negative electrode plate in a case,
Short-circuit current calculating means for calculating a short-circuit current of the secondary battery;
An abnormality determining means for determining the presence or absence of abnormality of the secondary battery based on the calculation result of the short circuit current calculating means;
A reference value setting means for setting a determination reference value according to the charging rate of the secondary battery,
The abnormality determination device for a secondary battery, wherein the abnormality determination unit determines that there is an abnormality in the secondary battery when the short-circuit current is greater than or equal to the determination reference value . In the secondary battery abnormality determination device according to claim 1 ,
The abnormality determination device for a secondary battery, wherein the reference value setting means sets the determination reference value according to a temperature of the secondary battery together with a charging rate of the secondary battery. In the secondary battery abnormality determination device according to claim 1 or 2 ,
Current change calculating means for calculating a change in the short circuit current within a predetermined period based on the calculation result of the short circuit current calculating means;
An abnormality determination device for a secondary battery, further comprising: estimation means for estimating a time when the short-circuit current reaches the determination reference value based on a calculation result of the current change calculation means.