JP2020136098A - Battery pack abnormality detection device - Google Patents

Abstract

To provide a battery pack abnormality detection device capable of more reliably detecting an abnormality in a battery cell.SOLUTION: The battery pack abnormality detection device includes: a laser device 11 and a light receiving device 12, disposed inside a battery pack 1 accommodating a plurality of battery cells 2; and an abnormality detection unit 14 for detecting an abnormality of the battery cell 2 based on a light receiving state of the light receiving device 12. The laser device 11 irradiates laser light L so that it is separated from a surface 3 of the battery cells 2 by a predetermined length. The abnormality detection unit 14 detects abnormality of the battery cells 2 when a first light receiving state in which the light receiving device 12 receives the laser light L from the laser device 11 is changed to a second light receiving state in which the light receiving device 12 does not receive the laser light L from the laser device 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a battery pack abnormality detection device that detects an abnormality in a vehicle battery pack.

Electric vehicles such as electric vehicles and hybrid vehicles are equipped with a battery pack for supplying power to the electric motor. The battery pack is configured by modularizing a plurality of battery cells and accommodating the plurality of modules in a case, and is arranged, for example, below the floor surface of the vehicle.

Battery packs are used with specified operating conditions (voltage, temperature, current load), but they may be used in harsh environments outside the operating temperature range or foreign matter may get inside the battery cells during the manufacturing process. , It is necessary to assume that an abnormality will occur in the battery cell due to storage or the like.

When an abnormality occurs in a battery cell, the energy inside the battery causes heat generation, an increase in cell internal pressure, venting (pressure release), smoke generation, and ignition. Such an event is called thermal runaway, and various techniques for detecting thermal runaway have been proposed in order to deal with it at an early stage (for example, Patent Document 1).

The technique proposed in Patent Document 1 utilizes the fact that when an abnormality such as deterioration or short circuit of a battery occurs, the internal pressure of the battery cell rises and the battery cell is deformed so as to swell. Specifically, the deformation of the thin-walled portion is detected by irradiating the thin-walled portion provided in a part of the battery cell with light and detecting the reflected light. Then, the expansion of the battery cell, that is, the abnormality is detected by the deformation of the thin portion.

However, since there are various deformation modes of the thin-walled portion, it is difficult to reliably receive the reflected light when the thin-walled portion is deformed.

Japanese Unexamined Patent Publication No. 2014-192104

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 more reliably detecting an abnormality in a battery cell.

A first aspect of the present invention for solving the above problems is to receive a light emitting means that is arranged inside a battery pack containing a plurality of battery cells and irradiates a laser beam and a laser beam emitted from the light emitting means. The light receiving means includes a light receiving means for detecting an abnormality in the battery cell based on the light receiving state of the light receiving means, and the light emitting means irradiates a laser beam so as to be separated from the surface of the battery cell by a predetermined length. In the abnormality detecting means, the light receiving means receives the laser light from the light emitting means from the first light receiving state, and the light receiving means does not receive the laser light from the light emitting means. The battery pack abnormality detection device is characterized in that when it changes to, the abnormality of the battery cell is detected.

In the first aspect, when the abnormality detecting means stops receiving light (from the first light receiving state to the second light receiving state), the abnormality is detected, so that the abnormality of the battery cell is detected more reliably than in the prior art. can do.

A second aspect of the present invention is the battery pack abnormality detecting device according to the first aspect, comprising a mirror that reflects the laser beam emitted from the light emitting means, and the plurality of mirrors are arranged side by side. It is an abnormality detection device of a battery pack, characterized in that the laser beam is reflected so that the laser beam passes between the battery cells.

In the second aspect, by reflecting one laser beam with a mirror, it is possible to detect an abnormality in a plurality of battery cells.

A third aspect of the present invention is the battery pack abnormality detection device according to the first or second aspect, wherein the light emitting means irradiates a plurality of laser beams so as to be separated from the surface of the battery cell by a predetermined length. , The laser beam is in an abnormality detecting device of a battery pack, characterized in that the laser light is arranged side by side in a direction away from the surface of the battery cell.

In the third aspect, the degree of expansion of the battery cell, that is, the degree of abnormality can be detected.

A fourth aspect of the present invention is the battery pack abnormality detection device according to any one of the first to third aspects, wherein the light emitting means is a plurality of lasers so as to be separated from the surface of the battery cell by a predetermined length. The abnormality detection device of the battery pack is characterized in that the light is irradiated and the laser light is arranged side by side in the direction along the surface of the battery cell.

In the fourth aspect, the degree of expansion of the battery cell, that is, the degree of abnormality can be detected.

A fifth aspect of the present invention is the battery pack abnormality detecting device according to the third or fourth aspect, wherein the abnormality detecting means is the first laser beam farthest from the central portion of the battery cell. The change from the first light receiving state to the second light receiving state is detected within a predetermined time from the time when the first light receiving state changes to the second light receiving state for the second laser light other than the first laser light. At that time, the battery cell is in an abnormality detection device of a battery pack, which is characterized in that it is determined that the battery cell is thermally out of control.

In the fifth aspect, deterioration over time of the battery cell and thermal runaway can be detected separately.

According to the present invention, there is provided an abnormality detection device for a battery pack that can more reliably detect an abnormality in a battery cell.

It is a top view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 1 (normal state). It is a top view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 1 (at the time of abnormality). It is a top view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 2 (normal state). It is a side view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 2 (normal state). It is a top view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 3 (normal state). It is a side view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 3 (normal state). It is a side view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 4 (normal state). It is a side view which shows the schematic structure of the abnormality detection device of the battery pack which concerns on Embodiment 4 (normal state). It is a figure which shows the process of the abnormality detection apparatus of the battery pack which concerns on Embodiment 5.

<Embodiment 1>
An abnormality detection device for a battery pack will be described with reference to FIG.
As shown in FIG. 1A, the abnormality detection device 10 of the present embodiment targets the battery pack 1 mounted on the electric vehicle as an abnormality detection target. The battery pack 1 is provided with a case (not shown) below the floor surface of the electric vehicle, and a plurality of (four in the example of the figure) battery cells 2a to 2d are modules inside the case. It has been converted and housed. The battery cells 2a to 2d are arranged side by side in one direction at predetermined intervals. It should be noted that the battery cells 2a to 2d are collectively referred to as the battery cells 2 without distinction.

Inside the case of the battery pack 1, a light receiving device 12 (FIG. 1 (a)) including a laser device 11 (denoted as LD in FIG. 1 (a)) as a light emitting means and a photodiode as a light receiving means. (Indicated as PD) is arranged.

The laser device 11 is a device that irradiates a laser beam as an example of directional light, and is a known device, so detailed description thereof will be omitted. The light receiving device 12 is a device including a photodiode that receives laser light and outputs an electric signal according to the intensity of the received light. Since such a light receiving device 12 is a known device, detailed description thereof will be omitted.

The laser device 11 and the light receiving device 12 are arranged so that the laser light L emitted from the laser device 11 to the light receiving device 12 is separated from the surface 3 of the battery cell 2 by a predetermined length. In other words, the laser beam L extends in a direction substantially horizontal to the surface direction of the surface 3 (a direction intersecting the normal line perpendicular to the surface 3), and the surface 3 is not irradiated. The laser device 11 irradiates the laser beam in such a direction, and the light receiving device 12 receives the laser beam. The state in which the laser beam L is separated from the surface 3 by a predetermined length in this way is when the battery cell 2 is not expanded due to an abnormality.

In the example shown in FIG. 1, the laser beam L passes between the battery cell 2b and the battery cell 2c. That is, the laser beam L is separated from both the surface 3 of the battery cell 2b and the surface 3 of the battery cell 2c by a predetermined length. As described above, the laser light L is irradiated to two battery cells 2 by one, but the laser light L may be one to one battery cell 2. , The laser beam L may be one for two or more battery cells 2.

The laser device 11 and the light receiving device 12 are connected to the control device 13. In the laser device 11, the control device 13 controls the start and stop of laser light irradiation. Further, the light receiving device 12 transmits the electric signal detected based on the laser beam to the control device 13.

The control device 13 is an ECU (Electronic Control Unit) mounted on an electric vehicle, and is a ROM that stores and stores a CPU, a control program, and the like, a RAM as an operating area of the control program, and an EEPROM that rewritably holds various data. , An interface unit that interfaces with peripheral circuits, etc. is included. The control device 13 controls each part of the electric vehicle via the interface unit to realize various controls such as traveling, braking, charging / discharging of the electric vehicle.

As one function of the control device 13, abnormality detection of the battery cell 2 is performed based on the light receiving state received by the light receiving device 12. The function of performing this abnormality detection is realized by the abnormality detection unit 14 implemented as a control program. The abnormality detection unit 14 detects an abnormality in the battery cell 2 when the first light receiving condition changes to the second light receiving condition.

The first light receiving state is a situation in which the light receiving device 12 receives light from the laser device 11, and specifically, a situation in which an electric signal is obtained from the light receiving device 12 is the first light receiving state.

FIG. 1B shows an electric signal detected by the light receiving device 12 in the first light receiving state. The horizontal axis represents time, and the vertical axis represents the strength (V) of the electric signal. In the first light receiving state, since the light receiving device 12 receives light from the laser device 11, a constant electric signal is obtained.

The second light receiving state is a situation in which the light receiving device 12 does not receive light from the laser device 11, and specifically, a situation in which an electric signal is not obtained from the light receiving device 12 is a second light receiving situation. As shown in FIG. 2A, it is assumed that the battery cell 2b has an abnormality and has expanded. When the battery cell 2b expands, the laser beam L is blocked. Therefore, the light receiving device 12 cannot receive light from the laser device 11. As shown in FIG. 2B, when the laser beam L is cut off by the battery cell 2b at time T1, the light receiving device 12 does not receive the light, so that the output electric signal is zero.

First, the abnormality detection unit 14 determines that the first light receiving state is obtained if the electric signal of the light receiving device 12 is obtained, and determines that the second light receiving state is obtained if the electric signal is not obtained. Since such a change in the light receiving state is caused by the expansion of the battery cell 2, it can be considered that an abnormality has occurred in the battery cell 2. Therefore, the abnormality detection unit 14 detects that an abnormality has occurred in the battery cell 2 due to the change.

The case is not limited to the case where it is determined that the first light receiving state is obtained when there is an electric signal of the light receiving device 12. For example, if the electric signal is equal to or greater than a predetermined value, it may be determined that the light receiving condition is the first. Similarly, if the electric signal is less than a predetermined value, it may be determined that the light receiving condition is the second.

Further, when the abnormality detection unit 14 detects an abnormality in the battery cell 2, the abnormality detection device 10 may be provided with an alarm system that warns the passenger that the abnormality has occurred. As the warning system, for example, a device for transmitting information such as a liquid crystal display and a speaker provided in an electric vehicle, and information (characters, images, figures, sounds) indicating that an abnormality has occurred in the battery cell 2 in such a device. Etc.) can be mentioned as one function (program) of the control device 13 for presenting.

Further, the abnormality detection of the battery cell 2 by the abnormality detection unit 14 may always function, or may function when a specific condition is satisfied. Specific conditions include, for example, that at least one of the ignition switch of the electric vehicle, the seat sensor for determining the seating of the occupant, and the manual switch for manually activating the abnormality detection of the battery cell 2 is turned on. By executing the abnormality detection when such a specific condition is satisfied, it is possible to reliably start the abnormality detection of the battery cell 2 when it is necessary to ensure the safety of the occupant.

The battery pack abnormality detection device 10 described above detects that the laser beam L is blocked by the expansion of the battery cell 2. Since the expansion of the battery cell 2 is caused by thermal runaway or deterioration of the battery cell over time, it is possible to detect an abnormality of the battery cell 2, that is, thermal runaway or deterioration by detecting such expansion.

Further, in the prior art, it is difficult to predict in what direction the reflected light will be reflected, so there is a high possibility that the reflected light will not be received. Therefore, it is difficult to detect the deformation of the battery cell 2 due to the abnormality. However, in the abnormality detection device 10 of the present invention, when the abnormality detection unit 14 stops receiving light (when the first light reception state changes to the second light reception state), the abnormality is detected, so that it is more reliable than the conventional technique. It is possible to detect an abnormality in the battery cell 2.

<Embodiment 2>
The abnormality detection device 10 according to the second embodiment will be described with reference to FIGS. 3 and 4. The same components as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 3, the abnormality detection device 10 includes a plurality of mirrors 15. The mirror 15 is arranged so that the laser beam L passes between the battery cells 2 with the reflection angle and arrangement appropriately adjusted. In the example of the figure, six mirrors 15 are arranged, and the laser beam L is continuously reflected by the plurality of mirrors 15. With such a mirror 15, the laser beam L reaches the light receiving device 12 in a plurality of times from the laser device 11. Further, the laser light L that is diffracted by the mirror 15 passes between the battery cells 2 arranged side by side, and is separated from the surface 3 of each battery cell 2 by a predetermined length.

The laser beam L is cut off when any one of the plurality of battery cells 2 expands. At that time, since the abnormality detection unit 14 detects the change from the first light receiving state to the second light receiving state, the abnormality of the battery cell 2 can be detected.

According to the abnormality detection device 10 of the present embodiment as described above, by reflecting one laser beam L by the mirror 15, it is possible to detect an abnormality in a plurality of battery cells 2. As a result, the number of parts of the laser device 11 and the light receiving device 12 for irradiating the laser light L can be reduced to reduce the cost.

Further, as shown in FIG. 4, when the battery cell 2 expands, the central portion 4 is most likely to expand. Therefore, it is preferable that the laser beam L passes through a position separated from the central portion 4 of the battery cell 2 by a predetermined length. This makes it easier to detect the expansion of the battery cell 2, and it is possible to reliably detect the abnormality of the battery cell 2 earlier.

<Embodiment 3>
The abnormality detection device 10 according to the third embodiment will be described with reference to FIGS. 5 to 6. The same components as those in the first and second embodiments are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 5, the laser device 11 of the abnormality detection device 10 irradiates a plurality of laser beams L1 to L3, and the light receiving device 12 receives the laser beams L1 to L3. These laser beams L1 to L3 may have the same frequency and output, or may be different. Similar to the second embodiment, the laser beams L1 to L3 reach the light receiving device 12 in a plurality of times from the laser device 11 by a mirror (not shown).

The laser beams L1 to L3 folded back by the mirror 15 are separated from the surface 3 of any battery cell 2 by a predetermined length. Further, as shown in FIG. 6, the laser beams L1 to L3 are arranged side by side along the direction away from the surface 3 of the battery cell 2. Specifically, the laser beam L1 passes through a position separated by a predetermined length from the surface 3 near the central portion 4 of the battery cell 2. The laser light L2 passes through a position separated from the central portion 4 by a predetermined length from the laser light L1. The laser light L3 passes through a position separated from the central portion 4 by a predetermined length from the laser light L2. The laser beams L1 to L3 are aligned in the height direction (Z direction), but may be displaced from each other.

Since the laser beams L1 to L3 are separated from the surface 3 by a predetermined length, the expansion of the battery cell 2 can be detected in three stages. For example, when the battery cell 2 begins to expand, first, only the laser beam L1 is blocked by the battery cell 2. When the battery cell 2 further expands, the laser light L2 is blocked by the battery cell 2, and then the laser light L3 is blocked by the battery cell 2.

The abnormality detection unit 14 detects a change from the first light receiving state to the second light receiving state for each of the laser beams L1 to L3. If a change is detected only in the laser beam L1, it is detected that the degree of expansion is relatively low. If changes are detected only in the laser light L1 and the laser light L2, it is detected that the expansion is moderate. If a change is detected in all of the laser beams L1 to L3, it is detected that the laser beam is considerably expanded. Depending on the degree of such expansion, it is possible to detect an abnormality in the battery cell 2 with a certain degree.

According to the abnormality detection device 10 of the present embodiment, the degree of expansion of the battery cell 2, that is, the abnormality is obtained by arranging the plurality of laser beams L1 to L3 so as to be separated from the surface of the battery cell 2 by a predetermined length. The degree of can be detected.

<Embodiment 4>
The abnormality detection device 10 according to the fourth embodiment will be described with reference to FIGS. 7 to 8. The same components as those in the first to third embodiments are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 7, the abnormality detection device 10 of the present embodiment irradiates and receives a plurality of laser beams L1 to L3 in the same manner as the abnormality detection device 10 of the third embodiment. The laser beams L1 to L3 are separated from the surface 3 of any battery cell 2 by a predetermined length, and are arranged side by side in the direction (Z direction) along the surface 3 of the battery cell 2. Specifically, the laser beam L1 passes through a position separated by a predetermined length from the surface 3 near the central portion 4 of the battery cell 2. The laser light L2 passes through a position separated above the laser light L1 in the Z direction. The laser light L3 passes through a position separated above the laser light L2 in the Z direction. The laser beams L1 to L3 are aligned at a distance (X direction) from the surface 3, but may be displaced.

As shown in FIG. 8, the surfaces 3a to 3c of the battery cell 2 represent the process of expansion of the battery cell 2 in three stages. The central portion 4 of the battery cell 2 swells most, and the closer to the end portion 5, the smaller the bulge.

On the other hand, since the laser beams L1 to L3 are separated by a predetermined length in the direction along the surface 3, the expansion of the battery cell 2 can be detected in three stages. For example, when the battery cell 2 begins to expand, the surface 3a blocks only the laser beam L1. Further, when the battery cell 2 expands, the surface 3b blocks the laser light L2, and then the surface 3c blocks the laser light L3.

The abnormality detection unit 14 detects a change from the first light receiving state to the second light receiving state for each of the laser beams L1 to L3. If a change is detected only in the laser beam L1, it is detected that the degree of expansion is relatively low. If changes are detected only in the laser light L1 and the laser light L2, it is detected that the expansion is moderate. If a change is detected in all of the laser beams L1 to L3, it is detected that the laser beam is considerably expanded. Depending on the degree of such expansion, it is possible to detect an abnormality in the battery cell 2 with a certain degree.

According to the abnormality detection device 10 of the present embodiment, the degree of expansion of the battery cell 2 is increased by arranging the plurality of laser beams L1 to L3 so as to be separated by a predetermined length along the surface of the battery cell 2. That is, the degree of abnormality can be detected.

<Embodiment 5>
The abnormality detection device 10 according to the fifth embodiment will be described with reference to FIG. The same components as those in the first to fourth embodiments are designated by the same reference numerals, and duplicate description will be omitted. The configuration of the abnormality detection device 10 of the present embodiment is the same as that of the abnormality detection device 10 according to the third and fourth embodiments.

The abnormality detection device 10 of the present embodiment detects an abnormality as follows. First, it is assumed that the laser beam L1 is blocked (step S1). That is, it is assumed that the abnormality detection unit 14 detects a change in the laser light L1 from the first light receiving state to the second light receiving state.

Next, the abnormality detection unit 14 detects whether the laser beam L2 is blocked (step S2). That is, the abnormality detection unit 14 detects a change in the laser light L2 from the first light receiving state to the second light receiving state.

When the laser light L2 is not blocked (step S2: No), the battery cell 2 determines that the deterioration level is 1 (step S3). When the laser beam L2 is blocked (step S2: Yes), the abnormality detection unit 14 waits for several seconds (step S4). After the lapse of the standby time, the abnormality detection unit 14 detects whether the laser beam L3 is blocked (step S5). That is, the abnormality detection unit 14 detects the change from the first light receiving state to the second light receiving state for the laser light L3.

When the laser beam L3 is not blocked (step S5: No), the battery cell 2 determines that the deterioration level is 2 (step S6). When the laser beam L3 is blocked (step S5: Yes), the abnormality detection unit 14 determines that thermal runaway has occurred (step S7). Then, the abnormality detection unit 14 activates the warning system (step S8).

According to the abnormality detection device 10 described above, it is determined that the battery cell 2 has a deterioration level 1 or a deterioration level 2. In other words, it can be detected that the battery cell 2 gradually expands and deteriorates over time. On the other hand, when the laser light L2 is blocked (step S2: Yes), and after waiting for a few seconds (step S4), when it is determined that the laser light L3 is blocked (step S5: Yes), the distance from the surface 3 is the longest. It means that the laser beam L3 was blocked in a short time. Therefore, it is possible to more reliably detect a sudden thermal runaway in which the battery cell 2 expands in a short time.

In this way, the abnormality detection unit 14 receives the laser light L2 at the timing when the laser light L3 farthest from the central portion 4 of the battery cell 2 is cut off (when the first light receiving state changes to the second light receiving state). When it is detected within a predetermined time (several seconds in step S4) from the time when is shut off, it is determined that the battery cell 2 is thermally runaway. As a result, the abnormality detection unit 14 can distinguish between the deterioration of the battery cell 2 over time and the thermal runaway.

The laser light L3 corresponds to the first laser light of the claim, and the laser light L2 (may be the laser light L1) is the second laser light of the claim (laser light other than the first laser light). Corresponds to.

<Other Embodiments>
Although one embodiment of the present invention has been described above, the present invention is, of course, not limited to the above-described embodiment.
For example, the number of battery cells 2 described in each embodiment is not particularly limited, and the number of laser beams is also not particularly limited. The distance (predetermined length) between the surface 3 of the battery cell 2 and the laser beam is not particularly limited, and the degree of expansion of the battery cell 2 may be estimated and set by actual measurement or simulation.

Further, the abnormality detection unit 14 is an example of the abnormality detection means according to the claim. The abnormality detecting means is implemented as one function (program) of the control device 13 as described in the embodiment, but is not limited to such an embodiment. For example, the abnormality detecting means may be implemented as an electronic circuit having the same function as the abnormality detecting unit 14, or may be an abnormality detecting unit mounted on a server device capable of communicating with the control device 13. ..

1 ... Battery pack, 2 ... Battery cell, 3 ... Surface, 10 ... Abnormality detection device, 11 ... Laser device (light emitting means), 12 ... Light receiving device (light receiving means), 13 ... Control device, 14 ... Abnormality detection unit (abnormality) Detection means), 15 ... Mirror

Claims (5)

A light emitting means that is arranged inside a battery pack containing a plurality of battery cells and irradiates a laser beam.
A light receiving means that receives the laser light emitted from the light emitting means, and a light receiving means.
An abnormality detecting means for detecting an abnormality in the battery cell based on the light receiving state of the light receiving means is provided.
The light emitting means irradiates a laser beam so as to be separated from the surface of the battery cell by a predetermined length.
The abnormality detecting means changes from a first light receiving state in which the light receiving means receives laser light from the light emitting means to a second light receiving state in which the light receiving means does not receive laser light from the light emitting means. An abnormality detection device for a battery pack, which detects an abnormality in the battery cell when the battery pack is used. In the battery pack abnormality detection device according to claim 1,
A mirror that reflects the laser beam emitted from the light emitting means is provided.
The mirror is an abnormality detection device for a battery pack, characterized in that the laser light is reflected so that the laser light passes between the battery cells arranged side by side. In the battery pack abnormality detection device according to claim 1 or 2.
The light emitting means irradiates a plurality of laser beams so as to be separated from the surface of the battery cell by a predetermined length.
An abnormality detection device for a battery pack, characterized in that the laser light is arranged side by side in a direction away from the surface of the battery cell. In the battery pack abnormality detection device according to any one of claims 1 to 3.
The light emitting means irradiates a plurality of laser beams so as to be separated from the surface of the battery cell by a predetermined length.
An abnormality detection device for a battery pack, characterized in that laser light is arranged side by side in a direction along the surface of the battery cell. In the battery pack abnormality detection device according to claim 3 or 4.
The abnormality detecting means is
The change from the first light receiving state to the second light receiving state for the first laser beam farthest from the center of the battery cell
When the second laser beam other than the first laser beam is detected within a predetermined time from the time when the first light receiving state changes to the second light receiving state.
An abnormality detection device for a battery pack, characterized in that the battery cell is determined to be in thermal runaway.

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