Power storage device and method for monitoring power storage element

Abstract

A power storage device 10 comprises: a plurality of power storage elements 30; a temperature adjustment member 40 that contacts the plurality of power storage elements 30 to adjust the temperatures of the power storage elements 30; and a thermal image camera 50. The thermal image camera captures a thermal image of the temperature adjustment member 40.

Description

Energy storage device and energy storage element monitoring method

[0001] The present invention relates to a technique for detecting abnormalities or signs of abnormalities in an energy storage element.

[0002] Patent Literature 1 discloses a technique for extracting high-temperature areas from an inspection target area of ​​a solar panel using an infrared camera, and Patent Literature 2 discloses a technique for predicting power conditioner failures using machine learning.

[0003] JP 2017-104003 A Patent No. 7246803 A

[0004] In recent years, a large number of energy storage elements have been used in mobile vehicles such as electric vehicles and stationary energy storage systems such as power storage stations. In many cases, the temperature of the energy storage elements is measured using a contact-type temperature sensor such as a thermistor.

[0005] Due to cost and space constraints, it is difficult to install contact temperature sensors on all storage elements. Therefore, conventionally, the temperature of only representative points among all storage elements is measured by contact temperature sensors. The conventional configuration in which the temperature is measured only at representative points with contact temperature sensors leaves room for improvement in terms of the quality of monitoring and the accuracy of anomaly detection.

[0006] An object of one embodiment of the present invention is to improve the quality of monitoring a plurality of power storage elements and the accuracy of detecting a sign of abnormality.

[0007] The power storage device includes a plurality of power storage elements, a temperature adjusting member that contacts the plurality of power storage elements to adjust the temperature of the power storage elements, and a thermal imaging camera that captures a thermal image of the temperature adjusting member.

[0008] The present invention can improve the quality of monitoring a plurality of storage elements and the accuracy of detecting signs of abnormality.

[0009] Side view of the energy storage device Plan view of the energy storage device Perspective view of the energy storage element Diagram showing the shape of the cooling pipe Diagram showing the internal structure of the battery panel Thermal image of the front end of the cooling pipe Thermal image of the front end of the cooling pipe Block diagram of the energy storage system Block diagram of the power generation system Side view of the energy storage device Perspective view of the lead-acid battery Perspective view of the element block and the energy storage module

[0010] An outline of an embodiment will be described below. (1) A power storage device includes a plurality of power storage elements, a temperature adjustment member that contacts the plurality of power storage elements to adjust the temperature of the power storage elements, and a thermal imaging camera. The thermal imaging camera captures a thermal image of the temperature adjustment member. The thermal image is an image that visualizes the surface temperature of an object.

[0011] According to the configuration (1) above, it is possible to detect temperature changes of the temperature adjustment member that contacts the multiple energy storage elements from the thermal image of the thermal imaging camera. By detecting the temperature change of the temperature adjustment member, it is possible to detect, for example, a temperature change caused by an abnormality or a sign of an abnormality in one of the multiple energy storage elements. As a result, it is possible to improve the quality of monitoring the energy storage elements and the accuracy of detecting signs of an abnormality.

[0012] (2) In the energy storage device described in (1), the plurality of energy storage elements may be arranged in a line along a long side or a short side of the temperature adjustment member with their bottom surfaces in contact with the temperature adjustment member. The temperature adjustment member may have an imaged portion that can be photographed by the thermal imaging camera at an end of the energy storage elements in the lined-up direction.

[0013] According to the configuration (2) above, when a temperature change occurs in one of the plurality of storage elements arranged in the long side direction (or short side direction) of the temperature adjustment member (for example, the storage element behind the foremost storage element), the temperature change appears in the thermal image as a temperature change in the imaged portion. Therefore, if only the imaged portion is imaged with the thermal imaging camera, it is possible to detect an abnormality or a sign of an abnormality in one of the plurality of storage elements arranged in the long side direction (or short side direction) of the temperature adjustment member.

[0014] (3) In the energy storage device described in (2), the temperature adjustment member may include a cooling plate on which the energy storage elements are placed, and a cooling pipe held inside the cooling plate and through which a liquid circulates. The imaged portion may be a part of the cooling pipe.

[0015] According to the configuration (3) above, if any of the multiple electric storage elements in contact with the temperature adjustment member becomes hot, heat is transferred from that electric storage element through the cooling pipe to the liquid inside. When the hot liquid circulates through the cooling pipe and moves to the imaged portion (part of the cooling pipe), the temperature of the imaged portion (part of the cooling pipe) increases, and a temperature change appears in the thermal image, making it possible to detect the temperature rise of the liquid. Therefore, by capturing an image of only the imaged portion (part of the cooling pipe) with a thermal imaging camera, it is possible to detect an abnormality or a sign of an abnormality in any of the multiple electric storage elements in contact with the temperature adjustment member.

[0016] (4) The energy storage device according to any one of (1) to (3) above may further include a housing that houses a plurality of energy storage elements and a temperature adjustment member that contacts the plurality of energy storage elements to adjust the temperature of the energy storage elements. The thermal imaging camera may be installed inside the housing. If a thermal imaging camera is installed outside the housing to perform imaging, only the surface temperature of the housing can be obtained. By installing the thermal imaging camera inside the housing, a thermal image of the imaged area can be captured.

[0017] The techniques described in (1) to (4) above can be applied to a method for monitoring a storage element.

[0018] 1 is a side view of the power storage device 10, and FIG. 2 is a plan view of the power storage device 10. FIG. 3 is a perspective view of the power storage element. The power storage device 10 includes a power storage module 20 and a thermal imaging camera 50.

[0019] The energy storage module 20 includes a plurality of energy storage elements 30 and a temperature adjustment member 40. As shown in Fig. 3, the energy storage elements 30 are, for example, prismatic cells (specifically, lithium ion battery cells) having a hollow rectangular parallelepiped case 31, and have a top surface 31A, a bottom surface 31B, short side surfaces 31C, and long side surfaces 31D. The long side surfaces 31D are perpendicular to the short side surfaces 31C and have a larger area than the short side surfaces 31C.

[0020] An electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode, and an electrolyte (electrolytic solution) are housed in the case 31. The energy storage element 30 also has a pair of cell terminals 32, 33 with opposite polarities on an upper surface 31A.

[0021] As shown in Figures 1 and 2, the multiple storage elements 30 are arranged in a row in the long side direction of the temperature adjustment member 40 (X direction in Figures 1 and 2), with their long sides 31D facing each other and their bottom surfaces 31B in contact with the temperature adjustment member 40.

[0022] Pouch cells (laminate type cells) may be used instead of prismatic cells as the energy storage elements 30. When using pouch cells, the long sides of the plurality of pouch cells are also opposed to each other, and the energy storage elements 30 are arranged side by side in the long side direction (X direction) of the temperature adjustment member 40 with their bottom surfaces 31B in contact with the temperature adjustment member 40.

[0023] The temperature adjustment member 40 is of a liquid-cooled type and includes a cooling frame 41 and cooling pipes 45. The cooling frame 41 is made of a metal material with high thermal conductivity and is box-shaped with a top surface, a bottom surface, and four side surfaces.

[0024] 2, the cooling frame 41 is rectangular in plan view with long sides 41A in the X direction and short sides 41B in the Y direction. As shown in FIG. 1, the upper surface of the cooling frame 41 is a mounting surface for the energy storage elements 30, and multiple energy storage elements 30 can be mounted on it while lined up in the X direction. A thermally conductive sheet 43 may be provided on the upper surface of the cooling frame 41.

[0025] The cooling frame 41 supports cooling pipes 45 therein. The cooling pipes 45 are metal pipes with high thermal conductivity, and a liquid (cooling water or coolant liquid) is circulated inside the cooling pipes 45 by a driving device such as a pump.

[0026] The cooling pipes 45 extend in the X direction so as to intersect with the energy storage elements 30 arranged on the cooling frame 41. The shape of the cooling pipes 45 may be a square ring shape along the inner surface of the cooling frame 41 as shown in Fig. 2, or may be a U-shape as shown in Fig. 4.

[0027] 2 omits the cell terminals of some of the energy storage elements 30 in order to show the shape of the cooling pipe 45. In FIG. 4 , all of the energy storage elements 30 are omitted.

[0028] By exchanging heat with a coolant liquid or the like through the cooling pipe 45, the temperature of each of the energy storage elements 30 arranged on the temperature adjustment member 40 can be adjusted.

[0029] 2, the front end 47 of the cooling pipe 45 protrudes from the front end surface 42 of the cooling frame 41. By allowing a portion of the cooling pipe 45 (in this example, the front end 47) to protrude from the cooling frame 41, it becomes possible to photograph the cooling pipe 45 with the thermal imaging camera 50. The front end 47 of the cooling pipe 45 is an example of the "imaged portion" in the present invention.

[0030] The thermal imaging camera 50 is located in front of (on the left in FIG. 1 ) the power storage module 20. The imaging surface of the thermal imaging camera 50 faces the front end 47 of the cooling pipe 45 protruding from the cooling frame 41, and captures a thermal image G of the front end 47. The thermal image G is an image that visualizes the surface temperature of an object.

[0031] The thermal imaging camera 50 may be an infrared camera that visualizes infrared rays emitted from an object, or may be any other camera that can capture a thermal image G. For example, it may be a camera that uses a temperature-sensitive liquid crystal display.

[0032] The thermal imaging camera 50 can be used by being attached to a housing. The housing is a container that houses the power storage module 20. Figure 5 is a cross-sectional view of the battery panel 100, showing the arrangement of the power storage module 20 within the battery panel.

[0033] The battery panel 100 includes a housing 110 and a plurality of power storage modules 20. The plurality of power storage modules 20 are arranged in multiple stages in the vertical direction within the housing 110. In this example, a thermal imaging camera 50 is installed on the inner surface of the front wall 120 of the housing 110, corresponding to each stage of the power storage modules 20.

[0034] 2. Abnormality Detection Operation of Energy Storage Elements 30 When any of the plurality of energy storage elements 30 in contact with the temperature adjustment member 40 becomes hot, the heat is transferred from the bottom surface 31B of the energy storage element 30 to the liquid inside via the cooling pipe 45. When the hot liquid circulates through the cooling pipe 45 and moves to the front end 47, the temperature of the front end 47 increases, and a temperature change appears in the thermal image G of the thermal imaging camera 50.

[0035] Fig. 6A is a thermal image G1 of the pipe front end 47 when all the energy storage elements 30 are normal, and Fig. 6B is a thermal image G2 of the pipe front end 47 when a high temperature abnormality occurs in some of the energy storage elements 30. The thermal image G2 in Fig. 6B has changed to a higher temperature than the thermal image G1 in Fig. 6A.

[0036] By monitoring only the thermal image G of the front end 47 of the cooling pipe 45 over time (time series), changes in the thermal image G can be used to detect abnormalities or signs of abnormalities in the multiple storage elements 30 in contact with the temperature adjustment member 40.

[0037] The changes in the thermal image G may be displayed on a monitor 70 as shown in FIG. 1 and monitored visually by an observer, or the changes in the thermal image G may be automatically detected by a computer and a warning issued.

[0038] The detection of changes in the thermal image G by the computer may be determined using a threshold value, or may be determined by collecting data on the thermal images G and using machine learning. For example, a machine learning model for determining abnormalities in the energy storage elements 30 may be created by machine learning data on thermal images G under normal conditions, and the abnormality determination may be performed using the machine learning model from input thermal images. The use of machine learning is expected to improve the accuracy of detecting abnormalities in the energy storage elements 30 and their signs.

[0039] 7 is a perspective view of an energy storage system S. The energy storage system S is a system that is connected to a power grid and adjusts the supply and demand of electricity, and includes, for example, a plurality of battery panels 100 and a PCS panel 150 that are arranged adjacent to each other outdoors. PCS stands for Power Conditioning System.

[0040] This technology can also be applied to container-type power storage devices 210A, 210B, and 210C installed alongside a mega solar power generation facility 200A, a wind power generation facility 200B, or a thermal power generation facility 200C, as shown in Fig. 8. Reference numeral 230 denotes a PCS.

[0041] The container-type power storage devices 210A to 210C are power storage devices that house multiple power storage modules 20 and a thermal imaging camera 50 inside a container. Furthermore, a thermal image G of the front end 47 of the cooling pipe 45 captured by the thermal imaging camera 50 may be transmitted to a monitoring center 250 via a network N, allowing for remote centralized monitoring of the state of the power storage modules 20 of each of the power storage devices 210A to 210C.

[0042] 4. Description of Effects This technology makes it possible to detect temperature changes in each energy storage element 30 that comes into contact with the temperature adjustment member 40, and improves the quality of monitoring the energy storage module 20 and the accuracy of detecting signs of abnormality compared to a conventional structure that monitors the temperature of only a representative point of the energy storage module 20.

[0043] As exemplified by the battery panel 100 in Fig. 5 , the energy storage module 20 is often used in a space with a limited height. Therefore, it is difficult to capture a thermal image G of the upper surfaces of multiple energy storage elements 30 with a thermal imaging camera 50 from a position sufficiently distant in the height direction (Z direction). Furthermore, when capturing images from the horizontal direction (i.e., when capturing images from the left in Fig. 5 ), it is possible to capture a thermal image G of the long side surface 31D of the foremost energy storage element 30 (the energy storage element 30 at the left end in Fig. 5 ), but it is difficult to capture a thermal image G of the long side surface 31D of the other energy storage elements 30 because they are in the shadow of the foremost energy storage element 30.

[0044] This technology solves these problems by focusing on the temperature adjustment member 40, and is advantageous in that it can detect abnormalities or signs of abnormalities not only in the forefront energy storage element 30 but also in other energy storage elements 30 that come into contact with the temperature adjustment member 40, even when the device is housed in a space with a limited height. Typically, when multiple energy storage modules 20 are arranged in multiple tiers on a battery panel 100, the higher the energy storage modules 20 that are arranged, the higher they tend to be due to the heat rising from below. Therefore, the temperature of the temperature adjustment member 40 of each tier of energy storage modules 20 may be monitored with a thermal imaging camera 50, and if the upper energy storage module 20 is hot, it may be determined to be normal, and if the energy storage modules 20 below the upper energy storage module 20 are hot, it may be determined to be an abnormality or a sign of an abnormality, and an alarm may be issued. It is conceivable that the battery panel 100 incorporates a heat source other than the energy storage elements, and the plurality of energy storage modules 20 are affected by heat from the heat source differently (for example, an energy storage module 20 that is farther away from the heat source is less affected by heat from the heat source, and there is a temperature gradient among the plurality of energy storage modules 20). In such a case, when the temperature difference (for example, absolute value) between the temperature adjustment members 40 of adjacent energy storage modules 20 exceeds a threshold value, it may be determined that an abnormality or a sign of an abnormality has occurred, and an alarm may be issued.

[0045] <Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

[0046] (1) In the above embodiment, one thermal imaging camera 50 is used to monitor one energy storage module 20. However, as shown in FIG. 9, one thermal imaging camera 50 may be used to monitor multiple energy storage modules 20 (e.g., multiple energy storage modules 20 arranged at different heights).

[0047] (2) In the above embodiment, the energy storage element is a lithium-ion battery cell. However, the energy storage element may be a lead-acid battery 270 as shown in FIG. 10 . The lead-acid battery 270 may experience thermal runaway due to heat generation caused by an increase in internal resistance. Thermal runaway occurs when the battery temperature becomes very high due to heat generation during charging, causing an increase in charging current, which further increases the temperature, creating a vicious cycle. Applying the present technology to the lead-acid battery 270 makes it possible to detect temperature abnormalities during charging and suppress thermal runaway in the lead-acid battery 270.

[0048] Because lead-acid batteries 270 are heavy, when they are housed in a battery panel, the shelf on which the lead-acid batteries 270 are placed is often made of metal. The metal shelf contacts the bottom surfaces of the lead-acid batteries 270 and exchanges heat (temperature regulation) with the batteries 270. Therefore, it is conceivable to have the metal shelf function as a temperature regulation member. If there is sufficient vertical space within the battery panel or battery compartment housing the lead-acid batteries 270, temperature changes in the batteries 270 may be detected using a thermal imaging camera positioned above the batteries 270. That is, a method for monitoring multiple energy storage elements may include capturing thermal images of the multiple energy storage elements from above using a thermal imaging camera and detecting abnormalities or signs of abnormalities in the energy storage elements from the thermal images. Conventionally, the internal temperature of the battery panel or the environmental temperature of the battery compartment is measured, and the measured temperatures are considered to be the temperatures of the multiple energy storage elements. In some cases, a thermistor is attached to a pilot cell (representative cell) to measure its temperature, and the measured temperature is considered to represent the temperature of multiple energy storage elements. In contrast, a thermal imaging camera can be used to photograph changes in the surface temperature of each energy storage element from above, providing a higher level of safety and peace of mind. The Arrhenius law (10°C / 2x law) can also be applied to thermal images to determine the deterioration and estimate the lifespan of the energy storage elements. While conventionally, deterioration and lifespan estimations have been performed based on the operational history of each energy storage element or on the measured internal resistance, a thermal imaging camera can be used as an alternative method. This method can be applied to monitoring not only lead-acid batteries 270 but also other energy storage elements, such as lithium-ion batteries.

[0049] The above-described method for monitoring multiple storage elements is suitable for application to emergency power supply devices such as DC power supplies and uninterruptible power supplies (UPS). The emergency power supply device has multiple storage elements (multiple lithium-ion battery cells or multiple lead-acid batteries) in a housing (battery panel or power supply panel). It is desirable for the emergency power supply device to detect abnormalities or signs of abnormalities in the storage elements during normal operation so that it can perform a predetermined discharge in an emergency such as a power outage. During normal operation, the storage elements of the emergency power supply device are charged with a minute current (e.g., float charging). Therefore, the temperature rise of conductive components such as bus bars during charging is limited, and the temperature change of the storage elements themselves can be accurately detected using a temperature adjustment component and a thermal imaging camera.

[0050] (3) In the above embodiment, the temperature adjustment member 40 is configured with the cooling plate 41 and the cooling pipe 45. The temperature adjustment member 40 may have a different configuration as long as it can adjust the temperature of the multiple energy storage elements 30, its surface temperature changes depending on the temperature of each energy storage element 30, and it has an imaged portion that can be imaged by the thermal imaging camera 50. Furthermore, instead of a thermal imaging camera, the energy storage device may include a detector such as the following. That is, the energy storage device may include multiple energy storage elements, a temperature adjustment member that contacts the multiple energy storage elements to adjust the temperature of the energy storage elements, and a detector that detects temperature changes in the temperature adjustment member. For example, instead of detecting temperature changes in a metal shelf member (not shown) on which the lead-acid battery 270 shown in FIG. 10 is placed, a detector such as a contact thermistor or a radiation thermometer may be used instead of a thermal imaging camera. Changes in the surface temperature of the cooling pipe 45 or the cooling frame 41 shown in FIGS. 2 and 4 may also be detected by a detector.

[0051] (4) In the above embodiment, the thermal imaging camera 50 is disposed in front of the power storage module 20 and photographs the front end 47 of the cooling pipe 45. The thermal imaging camera 50 may be disposed behind the power storage module 20 and photographs the rear end of the cooling pipe 45. Furthermore, if temperature changes due to heat generation from the power storage elements 30 can be detected, the cooling frame 41 may be the imaged part and photographed by the thermal imaging camera 50.

[0052] (5) The present technology can also be applied to a configuration in which a temperature adjustment member 340 is shared by multiple element blocks 330. The element block 330 is an element group consisting of multiple energy storage elements 30 arranged in one direction. The energy storage module 320 shown in FIG. 11 has two element blocks 330A and 330B arranged on the temperature adjustment member 340. The energy storage module 320 also includes a module case 350 that houses the two element blocks 330A and 330B. The module case 350 may have a double structure including a resin case 360 ​​that insulates the energy storage elements 30 and a metal case 370 that covers the resin case 360 ​​and is stronger than the resin case 360.

[0053] Each of the element blocks 330A and 330B has a plurality of energy storage elements 30 arranged in the short side direction (Y direction) of the temperature adjustment member 340, and the temperature adjustment member 340 has an imaged portion 347 disposed at the end of the short side direction (Y direction) corresponding to each of the element blocks 330A and 330B. When the temperature adjustment member 40 is liquid-cooled, the cooling pipe may be shared by the two element blocks 330A and 330B, or may be installed separately.

[0054] REFERENCE SIGNS LIST 10, 210 Electricity storage device 20, 320 Electricity storage module 30 Electricity storage element 40, 340 Temperature adjustment member 41 Cooling frame 45 Cooling pipe 47, 347 Front end portion (imaged portion) 50 Thermal imaging camera

Claims

1. An energy storage device comprising: a plurality of energy storage elements; a temperature adjustment member that contacts the plurality of energy storage elements to adjust the temperature of the energy storage elements; and a thermal imaging camera, wherein the thermal imaging camera takes a thermal image of the temperature adjustment member.

2. An energy storage device according to claim 1, wherein the plurality of energy storage elements are arranged in a line in the long side direction or short side direction of the temperature adjustment member with their bottom surfaces in contact with the temperature adjustment member, and the temperature adjustment member has an imaged portion at an end in the line of the energy storage elements that can be photographed by the thermal imaging camera.

3. An electric storage device according to claim 2, wherein the temperature adjustment member comprises a cooling plate on which a plurality of the electric storage elements are placed, and a cooling pipe held inside the cooling plate and through which a liquid circulates, and the imaged portion is a part of the cooling pipe.

4. An energy storage device according to claim 1 or 2, comprising a housing that houses a plurality of energy storage elements and the temperature adjustment member, and the thermal imaging camera is installed inside the housing.

5. A method for monitoring a plurality of energy storage elements in contact with a temperature adjustment member, comprising: taking a thermal image of the temperature adjustment member; and detecting an abnormality or a sign of an abnormality in the energy storage elements from the thermal image of the temperature adjustment member.

6. A method for monitoring a plurality of storage elements, comprising: capturing thermal images of the plurality of storage elements from above using a thermal imaging camera; and detecting abnormalities or signs of abnormalities in the storage elements from the thermal images.

7. An energy storage device comprising: a plurality of energy storage elements; a temperature adjustment member that contacts the plurality of energy storage elements to adjust the temperature of the energy storage elements; and a detection unit that detects a temperature change of the temperature adjustment member.

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