JP2020136224A - Battery pack abnormality detection device - Google Patents

Abstract

To provide a battery pack abnormality detection device capable of properly detecting a battery cell abnormality (opening of a safety valve).SOLUTION: In a battery pack 10 including a plurality of battery cells 30 provided with a safety valve 35 openable by an increase in internal pressure, an abnormality detection device 100 for detecting abnormality of the battery cells 30 includes: a vibration sensor 110, attached to each of the battery cells 30, for detecting a vibration of each of the battery cells; and a valve opening determination means 121 for determining valve opening of the safety valve 35 based on the detection result of the vibration sensor 110.SELECTED DRAWING: Figure 5

Description

The present invention relates to a battery pack abnormality detecting device for detecting an abnormality (particularly, heat chain) of a battery pack provided in a vehicle.

Electric vehicles such as electric vehicles and hybrid vehicles equipped with an electric motor as a power source are equipped with a battery pack for supplying power to the electric motor. The battery pack includes a plurality of battery cells and a case for accommodating the plurality of battery cells, and each battery cell is electrically connected in the case.

There are various structures of each battery cell, and for example, there is one in which a power generation element including a positive electrode plate, a negative electrode plate, and a separator is housed in a container together with an electrolytic solution, and the container is sealed by a lid member. In such a battery cell, for example, if foreign matter such as metal dust is mixed in the container, there is a possibility that an internal short circuit (short circuit) may occur due to the foreign matter.

When an internal short circuit occurs, the temperature inside the container rises and gas is generated, which may increase the pressure inside the container. For this reason, the battery cell is generally provided with a safety valve that opens when the pressure in the container rises to a predetermined value to suppress bursting due to the pressure rise.

Further, in a battery pack in which a plurality of battery cells are sealed in a container, when the safety valve is opened due to an internal short circuit, the internal pressure rises even in adjacent normal battery cells due to the influence of the heat of the battery cells. As a result, there is a risk of falling into a situation where the safety valve opens (so-called heat chain). Therefore, in the battery pack, it is preferable to appropriately detect an abnormality in each battery cell (opening of the safety valve) and take an early action.

Various techniques for detecting the opening of a safety valve (increased internal pressure) in a battery cell have been proposed (see, for example, Patent Document 1). In the technique described in Patent Document 1, a thin-walled portion is provided in a part (for example, a safety valve) of the container (exterior) of the battery cell, and the deformation of the thin-walled portion that is deformed as the pressure inside the container rises is a distortion sensor. It is detected by such as.

Japanese Unexamined Patent Publication No. 2014-192104

By detecting the deformation of the safety valve (thin-walled portion) with a strain sensor or the like as described in Patent Document 1, an increase in internal pressure can be detected, and further, opening of the safety valve can be detected. However, for example, depending on the structure of the battery pack (battery cell), it may not be possible to provide a strain sensor or the like on the safety valve, and development of a technique capable of more appropriately detecting the opening of the safety valve is desired.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a battery pack abnormality detection device capable of appropriately detecting an abnormality of a battery cell (opening of a safety valve).

One aspect of the present invention for solving the above problems is an abnormality detection device for detecting an abnormality in the battery cells in a battery pack including a plurality of battery cells provided with a safety valve that opens when the internal pressure rises. It is provided with a vibration detecting means attached to the battery cell to detect the vibration of each of the battery cells, and a valve opening determining means for determining the opening of the safety valve based on the detection result of the vibration detecting means. It is in the abnormality detection device of the battery pack, which is characterized by this.

According to the abnormality detection device for the battery pack of the present invention, the opening of the safety valve can be appropriately detected by detecting the vibration at a position away from the safety valve without detecting the deformation of the safety valve itself.

Here, it is preferable that a plurality of the vibration detecting means are attached to each battery cell, and the plurality of the vibration detecting means are arranged so that the distances from the safety valve are equal. By determining the opening of the safety valve based on the vibration waveforms detected by these a plurality of vibration detecting means, the opening of the safety valve can be determined more accurately.

Further, the valve opening determining means determines that the safety valve has opened on the condition that the detection result of the vibration detecting means and the vibration waveform at the time of opening the safety valve stored in advance are close to each other. Is preferable. Thereby, the opening of the safety valve can be determined more accurately.

Further, the abnormality detecting device includes a voltage detecting means for detecting the voltage of each battery cell, and the valve opening determining means further comprises the safety valve on the condition that the voltage of the battery cell is lowered to a predetermined value or less. It is preferable to determine that the valve has been opened. Thereby, the opening of the safety valve can be determined more accurately.

As described above, according to the battery pack abnormality detection device according to the present invention, it is possible to appropriately determine the opening of the safety valve. That is, it is possible to appropriately detect an abnormality in the battery pack such as thermal runaway (heat chain) of the battery cell. Therefore, when an abnormality occurs in the battery pack, it becomes possible to deal with it at an early stage.

It is a figure which shows an example of the usage mode of a battery pack. It is a perspective view which shows the schematic structure of the battery pack. It is a perspective view which shows the schematic structure of the battery module included in the battery pack. It is a figure which shows the appearance of the battery cell which comprises the battery module. It is a figure which shows the schematic structure of the abnormality detection apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows an example of the abnormality determination control by the abnormality detection apparatus which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The abnormality detection device according to the present invention is provided in a battery pack mounted on an electric vehicle to detect an abnormality in the battery pack. Specifically, the abnormality detection device detects the opening of the safety valve provided in the battery cell. First, the configuration of the battery pack provided with the abnormality detection device will be briefly described.

The vehicle 1 shown in FIG. 1 is, for example, an electric vehicle such as an electric vehicle or a hybrid vehicle, and is equipped with a battery pack 10 for supplying power to a motor (electric motor) (not shown).

As shown in FIG. 2, the battery pack 10 includes a pack outer case 13 including a pack tray 11 and a pack cover 12, and a battery module 20 housed in the pack outer case 13.

As shown in FIGS. 2 and 3, a plurality of battery modules 20 are housed in the battery pack 10 (pack exterior case 13), and each battery module 20 is provided with a plurality of battery cells arranged side by side in close proximity to each other. (Secondary battery) 30 is provided. Although not shown, these battery cells 30 are connected in series by a bus bar or the like. The number of battery cells 30 included in the battery module 20 is not particularly limited.

Each battery cell 30 is, for example, a sealed secondary battery such as a lithium ion battery, and includes a container 31 and a lid member 32 for sealing the container 31 as shown in FIG. Inside the container 31, an electrode body (power generation element) including a positive electrode plate, a negative electrode plate, and a separator is housed together with an electrolytic solution. Further, since the electrode body has a known structure, the description thereof is omitted here.

The lid member 32 is provided with a positive electrode terminal member 33 and a negative electrode terminal member 34, which are connected to the positive electrode plate or the negative electrode plate of the electrode body housed in the container 31, respectively. The lid member 32 is further provided with a safety valve 35 between the positive electrode terminal member 33 and the negative electrode terminal member 34.

The safety valve 35 is formed to be relatively fragile compared to other parts of the lid member 32. For example, when an internal short circuit occurs in the container 31, the internal pressure of the container 31 reaches a predetermined value. Then, it is configured to open the valve. As a result, even when the internal pressure of the container 31 rises, the gas in the container 31 is ejected to the outside from the opened safety valve 35. Therefore, the rupture of the container 31 due to the increase in the internal pressure can be suppressed.

Then, the abnormality detection device 100 according to the present embodiment is provided in such a battery pack 10 and detects an abnormality in each battery cell 30. Specifically, the abnormality detection device 100 detects the opening of the safety valve 35 as an abnormality of the battery cell 30.

As shown in the block diagram of FIG. 5, the abnormality detecting device 100 is composed of a vibration sensor (vibration detecting means) 110 for detecting the vibration of each battery cell 30 (vibration transmitted to the container 31 and the lid member 32) and the vibration sensor 110. It includes a control unit 120 that performs various controls based on the detection result.

The vibration sensor 110 detects the vibration (vibration waveform) of the battery cell 30 when the safety valve 35 is opened, and is attached to the lid member 32 on which the safety valve 35 is formed. In this embodiment, two vibration sensors 110 (110A, 110B) are attached to each battery cell 30.

Specifically, the first vibration sensor 110A and the second vibration sensor 110B are attached to the lid member 32 of each battery cell 30. That is, the first vibration sensor 110A and the second vibration sensor 110B are mounted on the lid member 32 which is flush with the safety valve 35. Further, the first vibration sensor 110A and the second vibration sensor 110B are arranged so that the distances from the safety valve 35 are substantially equal to each other. As shown in FIG. 5, the distance d1 from the safety valve 35 to the first vibration sensor 110A and the distance d2 from the safety valve 35 to the second vibration sensor 110B are the same.

The mounting positions of the first vibration sensor 110A and the second vibration sensor 110B are not particularly limited as long as they can detect the vibration generated when the safety valve 35 is opened. For example, the first vibration sensor 110A and the second vibration sensor 110B may be attached to the surface of the container 31 of the battery cell 30. Further, the first vibration sensor 110A and the second vibration sensor 110B may be provided at different distances from the safety valve 35.

The first vibration sensor 110A and the second vibration sensor 110B are connected to the control unit 120. Further, in the present embodiment, the abnormality detection device 100 includes a voltage sensor (voltage detecting means) 115 that detects the voltage (cell voltage) of each battery cell 30, and this voltage sensor 115 is also connected to the control unit 120. There is.

The control unit 120 includes a CPU, a ROM for storing and storing a control program, a RAM as an operating area for the control program, an EEPROM for holding various data rewritably, an interface unit for interfacing with peripheral circuits, and the like. It is configured.

In the present embodiment, the control unit 120 includes a valve opening determination means 121 and a notification means 122. The valve opening determination means 121 determines the valve opening of the safety valve 35 based on the detection results of the first vibration sensor 110A and the second vibration sensor 110B.

The control unit 120 stores in advance the vibration waveform (reference vibration waveform) when the safety valve 35 is opened, and the valve opening determination means 121 detects it by the first vibration sensor 110A and the second vibration sensor 110B. The resulting vibration waveform is compared with the reference vibration waveform, and it is determined that the safety valve 35 has been opened on the condition that each of them is close to the reference vibration waveform.

When the safety valve 35 is opened, a considerably large vibration (sound) is generated, and the vibration waveform has a peculiar shape. That is, the shape of the vibration waveform generated when the safety valve 35 is opened is clearly different from the shape of the vibration waveform generated by an external factor when the electric vehicle is normally traveling. Therefore, by comparing the vibration waveforms detected by the first vibration sensor 110A and the second vibration sensor 110B with the reference vibration waveform, it is possible to appropriately determine whether or not the safety valve 35 has been opened.

For example, the valve opening determination means 121 compares the vibration waveforms detected by the first vibration sensor 110A and the second vibration sensor 110B with the reference vibration waveform, obtains the degree of similarity (degree of similarity) between the two, and obtains the similarity. When the degree is equal to or higher than a preset threshold value, it is determined that the safety valve 35 has been opened. The method of obtaining the degree of similarity is not particularly limited and may be arbitrarily determined.

Further, when the valve opening determining means 121 determines that the vibration waveform is close to the reference vibration waveform, whether or not the timings at which the vibration waveforms are detected by the first vibration sensor 110A and the second vibration sensor 110B match. Is further determined. Then, the valve opening determination means 121 determines that the safety valve 35 has opened, provided that the timings match.

The first vibration sensor 110A and the second vibration sensor 110B are arranged so that the distances from the safety valve 35 are equal as described above. Therefore, the vibration waveform generated when the safety valve 35 is opened is detected by the first vibration sensor 110A and the second vibration sensor 110B at substantially the same timing.

On the other hand, even when a vibration waveform close to the reference vibration waveform is detected by the first vibration sensor 110A and the second vibration sensor 110B, if the vibration waveform is due to an external factor, the first vibration sensor There should be a time lag in the timing at which the vibration waveform is detected by the 110A and the second vibration sensor 110B. Therefore, when there is a time difference between the timings of the first vibration sensor 110A and the second vibration sensor 110B, it can be determined that the source of vibration is not the safety valve 35.

The first vibration sensor 110A and the second vibration sensor 110B may be provided at different positions from the safety valve 35 as described above, but in that case, the first vibration sensor 110A and the second vibration sensor 110B may be provided. When the timing at which the vibration waveform is detected by the vibration sensor 110B of No. 2 has a predetermined time difference according to the difference in the distance from the safety valve 35, it can be determined that the source of the vibration is not the safety valve 35.

Further, when the valve opening determination means 121 detects a vibration waveform that is close to the reference vibration waveform by the first vibration sensor 110A and the second vibration sensor 110B, the valve opening determination means 121 of the battery cell 30 based on the detection result of the voltage sensor 115. It is determined whether or not the cell voltage has dropped to a predetermined value or less. Then, the valve opening determination means 121 determines that the safety valve 35 has been opened on condition that the cell voltage has dropped to a predetermined value or less.

As described above, in the present embodiment, in the valve opening determination means 121, the vibration waveform detected by the first vibration sensor 110A and the second vibration sensor 110B is close to the reference vibration waveform, and the first vibration sensor When the vibration waveform close to the reference vibration waveform is detected by the 110A and the second vibration sensor 110B at substantially the same timing, and the voltage of the corresponding battery cell 30 drops to a predetermined value or less, the safety valve 35 Determines that the valve has opened. Thereby, it is possible to more appropriately determine whether or not the safety valve 35 of the battery cell 30 has been opened.

When the safety valve 35 is determined to have been opened by the valve opening determination means 121, the notification means 122 notifies (warns) the driver of the fact. The notification means 122, for example, causes an abnormality in the battery pack 10 by turning on / blinking the warning lamp 130, that is, a thermal chain is generated in a plurality of battery cells 30 included in the battery pack 10, or a plurality of heat chains are generated. Notifies the driver that a thermal chain may occur in the battery cell 30 of the above. The method of notifying the driver is not particularly limited, and for example, a warning sound or a voice may be emitted from the speaker.

Here, an example of abnormality detection control by the abnormality detection device 100 according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing an example of abnormality detection control by the abnormality detection device 100.

For example, when the power supply from the battery pack 10 to the motor is started, the abnormality detection device 100 starts monitoring the vibration waveform of each battery cell 30 (step S1). The timing at which the abnormality detection device 100 starts monitoring the vibration waveform of the battery cell 30 is not particularly limited. For example, monitoring may be started at the timing when the ignition switch of the electric vehicle is turned on, the timing when the seat sensor or the like detects that the occupant is seated, or the like. Of course, the monitoring may be started when the occupant manually activates the abnormality detection device 100.

Next, in step S2, it is determined whether or not the vibration waveform detected by the first vibration sensor 110A and the second vibration sensor 110B is close to the reference vibration waveform. When the determination in step S2 is repeated (step S2: No) and it is determined that the vibration waveform detected by the first vibration sensor 110A and the second vibration sensor 110B is close to the reference vibration waveform (step S2). : Yes), proceed to step S3.

In step S3, it is determined whether or not the timings at which the vibration waveforms are detected by the first vibration sensor 110A and the second vibration sensor 110B match. If there is a time difference in the detected timing (the time difference is larger than the threshold value) (step S3: No), it is determined that the detected vibration waveform is due to an external factor, and the monitoring of the vibration waveform is continued (step S1). ).

On the other hand, if the timings at which the vibration waveforms are detected by the first vibration sensor 110A and the second vibration sensor 110B match (step S3: Yes), the process proceeds to step S4, and further, the corresponding battery cell 30 It is determined whether or not the voltage (cell voltage V1) is equal to or less than a preset predetermined voltage V2.

When the safety valve 35 is opened, the cell voltage drops accordingly. Therefore, even when the vibration waveforms detected by the first vibration sensor 110A and the second vibration sensor 110B are close to the reference vibration waveform, when the cell voltage V1 is larger than the predetermined voltage V2 (step S4). : No), it is determined that the safety valve 35 is not opened, and the monitoring of the vibration waveform is continued (step S1). Further, in step S4, when the cell voltage V1 is equal to or lower than the predetermined voltage V2 (step S4: Yes), it is determined that the safety valve 35 is open, and the occupant (driver) is notified to that effect. (Step S5).

As described above, the abnormality detection device 100 according to the present embodiment detects the vibration waveform of each battery cell 30 included in the battery pack 10 and determines whether or not the safety valve 35 is opened based on the vibration waveform. Therefore, it is possible to suppress erroneous determination and appropriately determine an abnormality in the battery pack 10 (opening of the safety valve 35). Therefore, the occupant (driver) of the vehicle 1 can deal with the abnormality of the battery pack 10 at an early stage when an abnormality occurs.

Although one embodiment of the present invention has been described above, the present invention is, of course, not limited to the above-described embodiment.

In the above-described embodiment, the first vibration sensor and the second vibration sensor are provided at positions equidistant from the safety valve, but they do not necessarily have to be equidistant. In that case, even if the vibration waveform accompanying the opening of the safety valve is detected, there will be a time lag in the timing of detecting the vibration waveform between the first vibration sensor and the second vibration sensor. Therefore, in this case, it may be determined that the safety valve has been opened on the condition that a predetermined time difference occurs in the timing of detecting the vibration waveform between the first vibration sensor and the second vibration sensor.

Further, in the above-described embodiment, the configuration in which the first vibration sensor and the second vibration sensor are provided in the battery cell is illustrated, but of course, the battery cell may be provided with three or more vibration sensors.

Further, the battery cell may be provided with one vibration sensor. That is, in the above-described embodiment, it is determined that the safety valve has been opened on the condition that the timings at which the vibration waveforms are detected by the plurality of vibration sensors match, but the determination based on this condition is not performed. May be good.

Further, in the above-described embodiment, the vibration sensor is provided as the vibration detecting means, but the configuration of the vibration detecting means is not particularly limited as long as it can detect the vibration generated in the battery cell. It may be a strain gauge or the like.

Further, it is determined that the safety valve is opened on the condition that the voltage of the battery cell (cell voltage) is lowered to a predetermined value or less, but it is not necessary to make the determination based on this condition.

By making a judgment based on these conditions, it is possible to more accurately determine that the safety valve has opened, but the safety valve is provided on the condition that the vibration waveform detected by the vibration sensor is close to the reference vibration waveform. Appropriate determination can also be made by determining valve opening.

1 Vehicle (electric vehicle)
10 Battery pack 11 Pack tray 12 Pack cover 13 Pack exterior case 20 Battery module 30 Battery cell 31 Container 31 Safety valve 32 Lid member 33 Positive electrode terminal member 34 Negative electrode terminal member 35 Safety valve 100 Abnormality detection device 110 Vibration sensor (vibration detection means)
115 Voltage sensor (voltage detecting means)
120 Control unit 121 Valve opening determination means 122 Notification means 130 Warning lamp

Claims (4)

An abnormality detection device for detecting an abnormality in a battery cell in a battery pack including a plurality of battery cells provided with a safety valve that opens when the internal pressure rises.
A vibration detecting means attached to each battery cell to detect the vibration of each battery cell,
An abnormality detecting device for a battery pack, comprising: a valve opening determining means for detecting the opening of the safety valve based on the detection result of the vibration detecting means. The battery pack abnormality detection device according to claim 1.
A plurality of the vibration detecting means are attached to each battery cell.
A battery pack abnormality detecting device, wherein the plurality of vibration detecting means are arranged so as to have equal distances from the safety valve. The battery pack abnormality detection device according to claim 1 or 2.
The valve opening determining means determines that the safety valve has opened on the condition that the detection result of the vibration detecting means and the vibration waveform at the time of opening the safety valve stored in advance are close to each other. A battery pack abnormality detection device characterized by. The battery pack abnormality detection device according to claim 3.
Equipped with a voltage detecting means for detecting the voltage of each battery cell
The valve opening determining means is a battery pack abnormality detecting device, further comprising determining that the safety valve has opened, provided that the voltage of the battery cell has dropped to a predetermined value or less.

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