Battery system and battery cell assembly

Abstract

The battery system includes a battery pack including a plurality of battery cells and a plurality of pressure sensing pads connected in parallel to the plurality of battery cells, attached to outer surfaces of the plurality of battery cells, and having resistance values ​​that change depending on pressure applied thereto; and a Battery Management System (BMS) that derives a plurality of cell voltages for each of the plurality of battery cells and determines that the battery pack is in an abnormal state if at least one of the derived cell voltages is equal to or lower than a critical voltage.

Description

[Technical Field]

[0001] Cross-reference to related application(s) This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0187419 dated December 24, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present disclosure relates to a battery system and a battery cell assembly. [Background technology]

[0003] As the secondary battery market grows rapidly, ensuring the stability of battery use is becoming an important issue. Batteries can become dangerous due to various reasons, such as overheating, smoking, catching fire, and exploding. When a battery develops an abnormality and catches fire, gas may be generated inside the battery before the fire occurs, causing it to swell. When the battery swells, the pressure inside the battery increases. Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to Based on Detects battery abnormality so that The purpose is to [Means for solving the problem]

[0005] According to one aspect of the invention, a battery system includes a battery pack including a plurality of battery cells and a plurality of pressure sensing pads connected in parallel to the plurality of battery cells, attached to outer surfaces of the plurality of battery cells, and having resistance values that change depending on pressure applied thereto; and a Battery Management System (BMS) that derives a plurality of cell voltages for each of the plurality of battery cells and determines that the battery pack is in an abnormal state if at least one of the derived cell voltages is equal to or lower than a critical voltage.

[0006] Each of the plurality of pressure sensing pads may include a sensor unit attached to an outer surface of a corresponding one of the plurality of battery cells and including a pressure sensor whose resistance changes depending on pressure, a first wire connecting the sensor unit to a positive terminal of the corresponding battery cell, and a second wire connecting the sensor unit to a negative terminal of the corresponding battery cell.

[0007] Each of the pressure sensing pads may further include a coating portion formed in a shape covering the sensor portion, the first wiring, and the second wiring to fix the sensor portion, the first wiring, and the second wiring to one surface of the corresponding battery cell.

[0008] The sensor unit may have an infinite resistance when no pressure is applied to the pressure sensor, and may have a base resistance value when the pressure applied to the pressure sensor reaches a certain level.

[0009] The assembled resistance of the corresponding battery cell is a parallel combined resistance in which the resistance of the corresponding battery cell and the resistance of the sensor unit are connected in parallel, and the assembled resistance of the corresponding battery cell can be reduced as the resistance of the sensor unit is reduced.

[0010] The BMS may determine that an abnormality has occurred in the battery pack if the cell voltage of the corresponding battery cell decreases below the critical voltage due to a decrease in the assembly resistance of the corresponding battery cell.

[0011] When the BMS determines that an abnormality has occurred in the battery pack, it can stop operation of the battery pack.

[0012] According to another aspect of the invention, a battery cell assembly includes a battery cell and a pressure sensing pad connected in parallel to the battery cell and attached to one surface of the battery cell, the pressure sensing pad having a resistance value that changes depending on pressure applied thereto, the pressure sensing pad being attached to an outer surface of the battery cell and including a sensor unit including a pressure sensor whose resistance changes depending on pressure, a first wire connecting the sensor unit to a positive terminal of the battery cell, and a second wire connecting the sensor unit to a negative terminal of the battery cell.

[0013] The pressure sensing pad may further include a coating portion formed in a shape that covers the sensor portion, the first wiring, and the second wiring and fixes the sensor portion, the first wiring, and the second wiring to one side of the battery cell.

[0014] The sensor unit may have an infinite resistance when no pressure is applied to the pressure sensor, and may have a base resistance value when the pressure applied to the pressure sensor reaches a certain level.

[0015] As the resistance of the sensor unit decreases, an assembly resistance formed by connecting the resistance of the battery cell and the resistance of the sensor unit in parallel can be reduced. [Effects of the Invention]

[0016] In a battery system including a battery pack, the cell voltage of each battery cell is measured using pressure sensor pads connected in parallel to each of a plurality of battery cells, and a battery abnormality can be detected based on the measured cell voltage. Also, the battery abnormality can be notified in advance so that protective measures can be taken. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a circuit diagram that schematically illustrates a battery system according to one embodiment. [Figure 2]FIG. 1 is a schematic illustration of a battery cell assembly according to one embodiment. [Figure 3] FIG. 3 is a circuit diagram schematically showing a detailed configuration of the sensor unit shown in FIG. 2. [Figure 4] 1 is a diagram illustrating an example of a battery pack according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. Identical or similar components will be designated by identical or similar reference numerals, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "section" for components used in the following description are used or interchangeable solely for the convenience of writing the specification and do not have any distinct meanings or functions. Furthermore, when describing the embodiments disclosed herein, if it is determined that a detailed description of related publicly known technology may obscure the gist of the embodiments disclosed herein, such a detailed description will be omitted. Furthermore, the accompanying drawings are merely provided to facilitate understanding of the embodiments disclosed herein, and the accompanying drawings should not be construed as limiting the technical concepts disclosed herein, and all modifications, equivalents, or alternatives within the concept and technical scope of the present invention should be understood to be included.

[0019] Terms including ordinal numbers such as "first," "second," etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0020] In this application, the terms "comprise" or "have" and the like are intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof stated in the specification, and should be understood as not precluding the possible presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0021] When an abnormality occurs in a battery cell, the internal pressure of the battery cell increases, causing it to expand. This expansion of the battery cell is called swelling. A pressure sensor pad can be attached to the battery cell to detect swelling of the battery cell.

[0022] A battery system will be described below in which a pressure sensor pad is connected in parallel to each of the battery cells in a battery pack including a plurality of battery cells, and an abnormality in the battery pack can be detected based on the amount of change in the cell voltage of each of the plurality of battery cells due to the parallel connection of the pressure sensor pads.

[0023] A battery system including a pressure sensor pad will now be described with reference to FIGS. 1 to 4. FIG.

[0024] FIG. 1 is a circuit diagram illustrating a battery system according to one embodiment.

[0025] The battery system 1 may include a battery pack 10, a battery management system (BMS) 20, and relays 31 and 32. Although Fig. 1 shows one battery pack 10, the invention is not limited thereto, and the battery system 1 may include two or more battery packs.

[0026] The external device 2 may include at least one of a load such as an inverter or a converter and a charging device. If the external device 2 is a charger, both ends of the battery system 1 may be connected to the charger and may be charged by receiving power from the charger. If the external device 2 is a load, both ends of the battery system 1 may be connected to the load and power supplied by the battery pack 10 may be discharged through the load.

[0027] The battery pack 10 may include a plurality of battery cell assemblies 101-103 connected in series. The plurality of battery cell assemblies 101-103 connected in series may include a plurality of battery cells 11-13 and a plurality of pressure sensor pads 14-16. For example, the battery cell assembly 101 may include the battery cell 11 and the corresponding pressure sensor pad 14. Although FIG. 1 shows three battery cell assemblies, the invention is not limited in this respect, and the battery pack 10 may include two or more battery cell assemblies.

[0028] The BMS 20 measures the cell voltage of each of the battery cells 11-13 and can detect an abnormality in the battery pack 10 and / or each of the battery cells 11-13 based on the measured cell voltage and the critical voltage. The critical voltage may be predetermined as initial information.

[0029] The BMS 20 is connected to each of the battery cells 11-13 and can acquire voltage measurement signals VS1-VS4 measured across the battery cells 11-13 via input terminals P1-P4. The positive electrode of each of the battery cells 11-13 (e.g., 11) is connected to a corresponding input terminal (e.g., P1) among the input terminals P1-P3 via wiring, and the negative electrode of each of the battery cells 11-13 (e.g., 11) is connected to a corresponding input terminal (e.g., P2) among the input terminals P2-P4 via wiring. For example, the measurement signal VS1 is the positive electrode voltage of battery cell 11 and is input to the BMS 20 via input terminal P1, and the measurement signal VS2 is the negative electrode voltage of battery cell 11 or the positive electrode voltage of battery cell 12 and is input to the BMS 20 via input terminal P2.

[0030] The BMS 20 can derive multiple cell voltages for each of the multiple battery cells 11-13 from the multiple measurement signals VS1-VS4. For example, the BMS 20 can derive the cell voltage of the battery cell 11 based on the measurement signal VS1 and the measurement signal VS2.

[0031] The relays 31 and 32 are located on the wiring and electrically control the current path during charging and discharging of the battery pack 10. The closing and opening of the relays 31 and 32 are controlled by relay control signals RCS1 and RCS2 supplied from the BMS 20.

[0032] Each of the pressure sensor pads 14-16 is connected in parallel to each of the battery cells 11-13. Each of the pressure sensor pads 14-16 may include a pressure sensor whose resistance changes depending on the magnitude of applied pressure. For example, the pressure sensor may be a force sensing resistor (FSR).

[0033] The pressure sensor pads 14-16 may be attached to the outer surfaces of the plurality of battery cells 11-13. For example, each of the plurality of battery cells 11-13 may be mounted in a pouch-shaped outer case. Each of the pressure sensor pads 14-16 may be closely attached to one of the outer surfaces of the pouch in which the corresponding battery cell is mounted. Alternatively, the pressure sensor pads 14-16 may be attached to the inner surface of the pouch-shaped outer case or may be built into the outer case itself. For convenience of explanation, the pressure sensor pads 14-16 will be described below as being attached to the outer surfaces of the plurality of battery cells 11-13.

[0034] FIG. 2 is a schematic illustration of a battery cell assembly according to one embodiment.

[0035] The following describes the battery cell assembly 101. The description of the battery cell assembly 101 can be similarly applied to the remaining battery cell assemblies 102 and 103 among the plurality of battery cell assemblies 101-103.

[0036] In conventional battery packs containing multiple battery cells, thin FSR pressure sensors are inserted between the battery cells to detect pressure caused by expansion of the battery cells. In order to detect changes in battery cell pressure through pressure sensors, as many pressure sensors as possible must be inserted between the battery cells. In order for the BMS to receive the detection results of the pressure sensors, multiple channels and wires must be added for each pressure sensor. As such, the existing method required additional channels and wires as the number of pressure sensors increased, limiting the number of sensors that could be inserted inside the battery pack.

[0037] According to one embodiment disclosed herein, each of the pressure sensor pads 14-16 is connected in parallel to a corresponding one of the battery cells 11-13. When the resistance of the pressure sensor pad 14 connected in parallel to the battery cell 11 decreases, the assembled resistance of the battery cell assembly 101 decreases. The assembled resistance of the battery cell assembly means a parallel combined resistance obtained by connecting in parallel the resistance of the battery cell and the resistance of the sensor unit connected in parallel to the battery cell.

[0038] A decrease in the assembly resistance of the battery cell assembly 101 reduces the cell voltage of the battery cell 11. When the BMS 20 detects the decrease in the cell voltage of the battery cell 11, it can determine that the battery pack 10 in which a swollen battery cell occurs among the plurality of battery cells 11-13 is in an abnormal state. If the battery cell 11 among the plurality of battery cells 11-13 swells, or if the battery cell 12 adjacent to the battery cell 11 swells, the resistance of the pressure sensor pad 14 can decrease.

[0039] The battery cell assembly 101 may include a battery cell 11 and a pressure sensor pad 14 .

[0040] The battery cell 11 may include a body 110, a first terminal 111, and a second terminal 112. The first terminal 111 may be the positive terminal (or negative terminal) of the battery cell 11, and the second terminal 112 may be the negative terminal (or positive terminal) of the battery cell 11.

[0041] The pressure sensor pad 14 may include a sensor portion 141, wiring 142, and a coating portion 143. The pressure sensor pad 14 may be attached over at least a portion of one surface of the body portion 110. Alternatively, the pressure sensor pad 14 may be attached over at least a portion of one surface of the body portion 110 and at least a portion of the other surface of the body portion 110. The sensor portion 141 may include one or more pressure sensors, and the pressure sensors may be implemented as elements whose resistance changes depending on pressure. For example, the pressure sensor may be implemented as at least one FSR, and if there are multiple FSRs, the multiple FSRs may be connected in parallel.

[0042] The pressure sensor can include two electrodes and a film layer coated with a conductive material positioned between the two electrodes.

[0043] The wiring 142 may include a wiring 1421 that connects the sensor unit 141 to the first terminal 111 and a wiring 1422 that connects the sensor unit 141 to the second terminal 112 .

[0044] The wire 1421 may be electrically connected to the first terminal 111 by welding, and a weld 144 that connects and fixes the wire 1421 to the first terminal 111 by welding may be formed on one side of the first terminal 111. The wire 1422 may be electrically connected to the second terminal 112 by welding, and a weld 145 that connects and fixes the wire 1422 to the second terminal 112 by welding may be formed on one side of the second terminal 112.

[0045] The sensor unit 141 may be attached to a predetermined position on one surface of the body unit 110. The coating unit 143 is formed in a shape that covers the sensor unit 141 and the wiring 142, thereby fixing the sensor unit 141 and the wiring 142 to one surface of the body unit 110. The coating unit 143 may be implemented in the form of a flexible printed circuit board (FPCB).

[0046] An equivalent circuit of the sensor unit 141 will be described below with reference to FIG.

[0047] FIG. 3 is a circuit diagram illustrating a detailed configuration of the sensor unit shown in FIG.

[0048] The following description of the sensor portion 141 and its detailed configuration included in the pressure sensor pad 14 of the battery cell assembly 101 can be similarly applied to the sensor portion and its detailed configuration included in the pressure sensor pads of the remaining battery cell assemblies 102, 103 among the multiple battery cell assemblies 101-103.

[0049] The sensor unit 141 may include a series-connected basic resistor 1411 and a pressure sensor 1412. The pressure sensor 1412 may have a resistance value that varies between 0 and infinity depending on the applied pressure. For this reason, the pressure sensor 1412 is shown as a variable resistor in FIG. 3.

[0050] The sensor unit 141 has infinite resistance when no pressure is applied to the pressure sensor 1412, and the resistance of the sensor unit 141 decreases as the pressure applied to the pressure sensor 1412 increases. When the pressure applied to the pressure sensor 1412 reaches a certain level, the resistance value of the pressure sensor 1412 becomes 0, and the resistance of the sensor unit 141 may have the resistance value of the basic resistor 1411. The basic resistor 1411 may have a resistance of several kΩ.

[0051] One end of the sensor unit 141 may be connected to the first terminal 111 through a wire 1421 , and the other end of the sensor unit 141 may be connected to the second terminal 112 through a wire 1422 .

[0052] When the plurality of pressure sensor pads 14-16 are connected in parallel to each of the plurality of battery cells 11-13, the resistance of each battery cell (e.g., 11) of the plurality of battery cells 11-13 is connected in parallel to the resistance of the sensor unit (e.g., 141) of the corresponding pressure sensor pad (e.g., 14) among the plurality of pressure sensor pads 14-16. The resistance of the battery cell may include the internal resistance of the battery cell.

[0053] The assembly resistance of each of the plurality of battery cell assemblies 101-103 may be represented by a parallel combined resistance obtained by connecting in parallel the cell resistance of each of the plurality of battery cells 11-13 and the resistance of each of the sensor units of the plurality of pressure sensor pads 14-16. Therefore, the assembly resistance of each of the plurality of battery cell assemblies 101-103 (e.g., 101) may be reduced by reducing the resistance of the corresponding sensor unit (e.g., 141).

[0054] In addition, when a battery cell (e.g., 11) among the plurality of battery cells 11-13 expands and applies pressure to the pressure sensor of the adjacent battery cell (e.g., 12), the resistance of the sensor portion corresponding to the adjacent battery cell 12 may decrease.

[0055] As the resistance of the sensor unit 141 decreases, the assembly resistance of the corresponding battery cell assembly 101 and the cell voltage of the battery cell 11 to which the pressure sensor pad 14 is connected in parallel may decrease.

[0056] The BMS 20 derives the cell voltages of the plurality of battery cells 11-13, and when at least one of the plurality of cell voltages drops below a critical voltage, it can determine that one of the plurality of battery cells 11-13 is in an abnormal state of swelling and that an abnormality has occurred in the battery pack 10. When the BMS 20 determines that an abnormality has occurred in the battery pack 10, it can perform a protective operation for the pack abnormality and send an external notification.

[0057] The protective action against the pack abnormality may include an action to stop the operation of the battery pack 10. For example, when the BMS 20 determines that an abnormality has occurred in the battery pack 10, it may stop charging and discharging the battery pack 10.

[0058] The BMS 20 may determine that at least one of the battery cells 11-13 is an abnormal cell when at least one of the cell voltages decreases below a critical voltage based on the cell voltages.

[0059] For example, when swelling occurs in the battery cell 12, pressure may be applied to at least one of the pressure sensors corresponding to the adjacent battery cells 11 and 13. In this case, the cell voltage of the battery cell 12 where swelling occurs drops more than the cell voltages of the adjacent battery cells 11 and 13, so the BMS 20 can determine that the battery cell 12 is an abnormal cell.

[0060] The BMS 20 can classify the state of each of the battery pack 10 and / or the plurality of battery cells 11-13 into at least one abnormal symptom stage based on the plurality of cell voltages.

[0061] FIG. 4 is a diagram illustrating an example of a battery pack according to an embodiment.

[0062] The battery pack 10 includes a plurality of battery cell assemblies 101-103, each of which (e.g., 103) includes one of the plurality of battery cells 11-13 (e.g., 13) and a corresponding pressure sensor pad (e.g., 16) among the plurality of pressure sensor pads 14-16. The plurality of battery cells 11-13 may be stacked with a predetermined distance between the cells. Each of the plurality of pressure sensor pads 14-16 may be attached to one side of the plurality of battery cells 11-13 and may be connected and fixed between the positive and negative electrodes of each of the plurality of battery cells 11-13 by welding.

[0063] 4 shows three battery cell assemblies, the invention is not limited thereto, and the battery pack 10 may include two or more battery cell assemblies. The battery cell assembly 103 will now be described. The description of the battery cell assembly 103 can be similarly applied to the remaining battery cell assemblies 101 and 102 among the plurality of battery cell assemblies 101-103.

[0064] The battery cell 13 includes a body 130 and a first terminal 131. The first terminal 131 may be the positive terminal (or negative terminal) of the battery cell 13.

[0065] The pressure sensor pad 16 may include a sensor portion 161, a wiring 162, a coating portion 163, and a welding portion 164. The wiring 162 may include a wiring 1621 and a wiring 1622 that connect the sensor portion 161 and the first terminal 131.

[0066] The welding portion 164 may be formed on one surface of the first terminal 131 to electrically connect the wire 1621 to the first terminal 131. The connection portion of the wire 1621 to the first terminal 131 may be fixed by the welding portion 164.

[0067] 4, a second terminal is located on the surface opposite to the surface on which the first terminal 131 of the battery cell 13 is located. In the same manner, the wire 1622 may be electrically connected to the second terminal by welding.

[0068] The coating portion 163 can be formed in a shape that covers the sensor portion 161 , the wiring 1621 and the wiring 1622 .

[0069] The descriptions regarding the sensor portion 141, the wiring 142, the coating portion 143, and the welded portions 144 and 145 in FIG. 2 can be similarly applied to the sensor portion 161, the wiring 162, the coating portion 163, and the welded portion 164 in FIG.

[0070] As described above, in the battery system 1 according to one embodiment, when the abnormal pressure of the battery cells 11-13 increases, the FSR reacts, and the resistance of the sensor unit (e.g., 141) may decrease from infinity to a base resistance value, and the cell voltage of the battery cells 11-13 may decrease due to the decrease in the resistance of the sensor unit 141. The BMS 20 may detect an abnormality in the battery pack 10 and / or the plurality of battery cells 11-13 based on the change in the battery cell voltage.

[0071] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these, and various modifications and improvements made by a person having ordinary skill in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. a battery pack including a plurality of battery cells and a plurality of pressure sensing pads electrically connected in parallel to the plurality of battery cells and attached to outer surfaces of the plurality of battery cells, the resistance value of which changes depending on pressure applied thereto; a battery management system (BMS) that derives a plurality of cell voltages for each of the plurality of battery cells, and determines that the battery pack is in an abnormal state if at least one of the derived cell voltages is equal to or lower than a critical voltage; The cell voltage of each of the plurality of battery cells decreases as the resistance of a pressure sensing pad attached to the corresponding battery cell decreases with the increase in pressure.

2. Each of the plurality of pressure sensitive pads comprises: a sensor unit attached to an outer surface of a corresponding one of the plurality of battery cells, the sensor unit including a pressure sensor whose resistance changes depending on pressure; a first wiring connecting the sensor unit and the positive electrode terminal of the corresponding battery cell; The battery system according to claim 1 , further comprising: a second wiring connecting the sensor unit and a negative terminal of the corresponding battery cell.

3. Each of the plurality of pressure sensitive pads comprises:

3. The battery system of claim 2, further comprising a coating portion formed in a shape that covers the sensor portion, the first wiring, and the second wiring to fix the sensor portion, the first wiring, and the second wiring to one surface of the corresponding battery cell.

4. The sensor unit When no pressure is applied to the pressure sensor, it has infinite resistance; 4. The battery system of claim 2, wherein the pressure sensor has a base resistance value when the pressure applied to the pressure sensor reaches a certain level.

5. The assembly resistance of the corresponding battery cell is: a parallel combined resistance in which the resistance of the corresponding battery cell and the resistance of the sensor unit are connected in parallel; The battery system according to claim 4 , wherein a decrease in the resistance of the sensor unit reduces an assembled resistance of the corresponding battery cell.

6. The BMS includes: The battery system according to claim 5 , wherein when a cell voltage of the corresponding battery cell decreases below the critical voltage due to a decrease in assembly resistance of the corresponding battery cell, it is determined that an abnormality has occurred in the battery pack.

7. The BMS includes: The battery system according to claim 6 , wherein when it is determined that an abnormality has occurred in the battery pack, the operation of the battery pack is stopped.

8. A battery cell; a pressure sensing pad connected in parallel to the battery cell and attached to one surface of the battery cell, the resistance of which changes depending on pressure applied thereto; The pressure sensitive pad a sensor unit attached to an outer surface of the battery cell and including a pressure sensor whose resistance changes depending on pressure; a first wiring connecting the sensor unit and a positive electrode terminal of the battery cell; a second wiring connecting the sensor unit and a negative electrode terminal of the battery cell; The cell voltage of the battery cell decreases as the resistance value decreases due to the increase in the pressure. Battery cell assembly.

9. The pressure sensitive pad 9. The battery cell assembly of claim 8, further comprising a coating portion formed in a shape that covers the sensor portion, the first wiring, and the second wiring to fix the sensor portion, the first wiring, and the second wiring to one surface of the battery cell.

10. The sensor unit When no pressure is applied to the pressure sensor, it has infinite resistance; The battery cell assembly of claim 8 or 9, wherein the pressure sensor has a base resistance value when the pressure applied to the pressure sensor reaches a certain level.

11. The battery cell assembly of claim 10 , wherein an assembly resistance formed by connecting the resistance of the battery cell and the resistance of the sensor unit in parallel is reduced as the resistance of the sensor unit is reduced.

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