Cell monitoring method and device

Abstract

To provide a cell monitoring method and device.SOLUTION: The cell monitoring method includes the steps of: measuring an open circuit voltage of each of a plurality of cells in a first idle period; estimating a capacity of each of the plurality of cells by using the open circuit voltage of each of the plurality of cells measured in the first idle period; measuring an open circuit voltage of each of the plurality of cells in a second idle period next to the first idle period; estimating a capacity of each of the plurality of cells by using the open circuit voltage of each of the plurality of cells measured in the second idle period; and detecting an internal short-circuiting cell on the basis of the capacity in the first idle period and the capacity in the second idle period of each of the plurality of cells.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present description relates to a cell monitoring method and apparatus. [Background technology]

[0002] Since ESS (Energy Storage System) is composed of many battery cells, if a certain cell catches fire due to an internal short circuit, it is highly likely that the fire will spread to adjacent cells and cause the entire system to burn down. Therefore, it is very important to detect internal short circuits in cells early and notify the system so that it can be stopped and safety measures can be taken before a fire occurs.

[0003] When an internal cell short circuit occurs, the cell capacity continues to decrease, so the internal cell short circuit is usually identified by estimating the amount of decrease in the cell capacity. However, to estimate the amount of decrease in capacity, it is necessary to accurately calculate the charge / discharge capacity of the cell, which is difficult to accurately calculate due to various factors such as the accuracy of the current sensor, efficiency according to temperature and charge / discharge rate, current consumption by the battery management system, self-discharge amount of the cell, and current consumption due to cell balancing. Summary of the Invention [Problem to be solved by the invention]

[0004] At least one of the embodiments provides a cell monitoring method and apparatus that can accurately detect an internally shorted cell.

[0005] According to an embodiment, a method for monitoring a plurality of cells in a battery module using a cell monitoring device may be provided, the cell monitoring method including the steps of: measuring an open circuit voltage of each of the plurality of cells in a first rest period; estimating a capacity of each of the plurality of cells using the open circuit voltage of each of the plurality of cells measured in the first rest period; measuring an open circuit voltage of each of the plurality of cells in a second rest period following the first rest period; estimating a capacity of each of the plurality of cells using the open circuit voltage of each of the plurality of cells measured in the second rest period; and detecting an internal short-circuited cell based on the capacity of each of the plurality of cells in the first rest period and the capacity of each of the plurality of cells in the second rest period.

[0006] The detecting step may include a step of calculating an amount of capacity reduction for each of the plurality of cells based on a difference between a capacity in the first rest period and a capacity in the second rest period for each of the plurality of cells, and a step of comparing an amount of capacity reduction of a first cell among the plurality of cells with an average amount of capacity reduction of the remaining cells of the plurality of cells excluding the first cell to determine whether or not an internal short circuit exists in the first cell.

[0007] The determining step may include a step of determining that the first cell is an internally short-circuited cell if a difference between a capacity loss of the first cell and an average capacity loss of the remaining cells excluding the first cell is greater than a set threshold.

[0008] The cell monitoring method may further include a step of calculating a consumed capacity of each of the plurality of cells in a discharge interval and a charge interval, and the step of calculating a capacity reduction amount of each of the plurality of cells may include a step of calculating a capacity reduction amount of each of the plurality of cells by reflecting a consumed capacity of each of the plurality of cells in a difference between a capacity of each of the plurality of cells in the first rest interval and a capacity of each of the plurality of cells in the second rest interval.

[0009] The step of calculating the consumed capacity of each of the plurality of cells may include the steps of connecting the battery module to a load in the discharging section, and connecting the battery module to a charging device in the charging section.

[0010] The step of measuring the open circuit voltage may include cutting off a current supply to the battery module.

[0011] According to another embodiment, a cell monitoring device for managing a plurality of cells by setting a rest period, a discharge period, and a charge period as one operation cycle may be provided, the cell monitoring device including an open circuit voltage calculation unit for measuring an open circuit voltage of each of the plurality of cells in the rest period of each operation cycle and estimating a capacity of each of the plurality of cells using the open circuit voltage of each of the plurality of cells, a consumption capacity calculation unit for calculating a consumption capacity of each of the plurality of cells in the discharge period and the charge period of each operation cycle, and a shorted cell detection unit for calculating a capacity reduction amount of each of the plurality of cells based on the capacity of each of the plurality of cells and the consumption capacity of each of the plurality of cells in each operation cycle and detecting an internally shorted cell based on the capacity reduction amount of each of the plurality of cells.

[0012] The short-circuit cell detection unit may calculate a capacity reduction amount of each of the plurality of cells by reflecting a consumption capacity of each of the plurality of cells calculated in the first operation cycle as a difference between a capacity of each of the plurality of cells estimated in a pause section of a first operation cycle and a capacity of each of the plurality of cells estimated in a pause section of a second operation cycle immediately before the first operation cycle.

[0013] The short-circuit cell detection unit can detect whether or not an internal short circuit exists in the first cell by comparing the amount of capacity reduction of a first cell among the plurality of cells with the average amount of capacity reduction of the remaining cells excluding the first cell.

[0014] The short-circuit cell detection unit can determine that the first cell is an internally short-circuited cell when a difference between an amount of capacity reduction of a first cell among the plurality of cells and an average amount of capacity reduction of the remaining cells excluding the first cell is greater than a set threshold.

[0015] The cell monitoring device may further include a switch control unit that disconnects a battery module including the plurality of cells from an external device in the rest period and connects the battery module to the external device in the discharge period and the charge period.

[0016] According to at least one of the embodiments, the open circuit voltage calculated in the pause section is used to calculate the cell capacity, thereby making it possible to more accurately detect an internally shorted cell. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing a battery pack according to an embodiment. [Diagram 2] 1 is a diagram illustrating a method of operating a battery pack according to an embodiment. [Diagram 3] 1 is a diagram illustrating a cell monitoring method according to an embodiment. [Figure 4] 1 is a diagram showing the capacities of a normal cell and an internally shorted cell. [Diagram 5] 5 is an enlarged view of part A shown in FIG. 4. [Figure 6] 1 illustrates a cell monitoring device according to an embodiment. [Figure 7] 13 is a diagram showing a cell monitoring device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, with reference to the accompanying drawings, an embodiment of the present invention will be described in detail so that a person having ordinary skill in the art to which the present invention pertains can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not necessary for the explanation are omitted, and similar parts are given similar reference numerals throughout the specification. In the flowcharts described with reference to the drawings, the order of operations may be changed, multiple operations may be merged, certain operations may be divided, or certain operations may not be performed.

[0019] Throughout the specification and claims, when a part "comprises" other elements, this means that the part may further include the other elements, not excluding the other elements, unless specifically stated to the contrary.

[0020] Additionally, expressions described in the singular can be construed as singular or plural, unless the explicit expression such as "one" or "single" is used.

[0021] In addition, 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. For example, the first component may be named the second component, and the second component may be named the first component, without departing from the scope of the present disclosure.

[0022] In addition, when a component is "connected" to another component, this includes not only the case where the component is "directly or physically connected" but also the case where the component is "indirectly or non-contactingly connected" with another component therebetween, or the case where the component is "electrically connected." On the other hand, when a component is described as being "directly connected" to another component, it should be understood that there is no other component between them.

[0023] FIG. 1 is a diagram showing a battery pack according to an embodiment.

[0024] 1, a battery pack 1 may include at least one battery module 10, a switch 20, and a cell monitoring device 30. The battery pack 1 may further include terminals (T+, T-).

[0025] The battery pack 1 can be connected to an external charging device or load via terminals (T+, T-), and can be charged by the charging device and discharged by the load.

[0026] At least one battery module 10 may include a number of cells 11, 12, 13, 14 electrically connected in series and / or parallel to each other, with only four cells 11, 12, 13, 14 shown in FIG.

[0027] The switch 20 can control a current path during charging and discharging of the battery module 10. The closing and opening of the switch 20 can be controlled by a switch control signal (SCS) provided from the cell monitoring device 30.

[0028] The cell monitoring device 30 can control and manage the overall operation of the battery pack 1. The cell monitoring device 30 can monitor the overall state of the battery module 10 and the cells 11, 12, 13, and 14 included in the battery module 10, and perform various control functions for adjusting the state of the battery module 10 and the cells 11, 12, 13, and 14 included in the battery module 10. As an example, the cell monitoring device 30 can control the charge / discharge current of the battery module 10 based on information such as the cell voltages and battery currents of the multiple cells 11, 12, 13, and 14, and perform a cell balancing operation on the multiple cells 11, 12, 13, and 14.

[0029] The cell monitoring device 30 can measure the voltages of the multiple cells 11, 12, 13, 14, or can receive the voltages of the multiple cells 11, 12, 13, 14. The cell monitoring device 30 can measure the battery current, or can receive the battery current measured by a current sensor.

[0030] The cell monitoring device 30 can be, for example, a battery management system (BMS).

[0031] According to the embodiment, the cell monitoring device 30 can detect an internally short-circuited cell by monitoring a plurality of cells 11, 12, 13, 14. The cell monitoring device 30 can detect an internally short-circuited cell by calculating the capacity reduction amount of each cell 11, 12, 13, 14 and comparing the capacity reduction amount of each cell 11, 12, 13, 14 with the capacity reduction amount of the remaining cells excluding the cell in question.

[0032] FIG. 2 is a diagram illustrating a method of operating a battery pack according to an embodiment.

[0033] 2, the battery pack 1 may be operated by setting a discharging section, a charging section, and a resting section as one operation cycle. The resting section may be a section for stabilizing the battery pack 1. The battery pack 1 may perform a discharging operation, a charging operation, and a resting operation according to the operation cycle.

[0034] In the discharging section, the cell monitoring device 30 can set the switch 20 to a turn-on state to connect the battery module 10 to a load. The battery module 10 can be discharged by using the load.

[0035] In the charging section, the cell monitoring device 30 can set the switch 20 to a turned-on state to connect the battery module 10 to a charging device. The battery module 10 can be charged by the charging device.

[0036] In the pause section, the cell monitoring device 30 sets the switch 20 to a turn-off state to stabilize the voltage of the battery module 10. In the pause section, no current flows through the battery module 10.

[0037] The cell monitoring device 30 monitors the states of the cells 11, 12, 13, and 14 in the discharging and charging sections, and can control the discharging and charging of the cells according to the states of the cells 11, 12, 13, and 14, and can maintain the voltages of the cells 11, 12, 13, and 14 at the same level through cell balancing.

[0038] FIG. 3 is a diagram illustrating a cell monitoring method according to an embodiment.

[0039] Referring to FIG. 3, the battery pack 1 can perform a discharging operation, a charging operation, and a resting operation according to an operation cycle.

[0040] The cell monitoring device 30 measures the open circuit voltage (OCV) of each cell 11, 12, 13, 14 of the battery module 10 during the rest period (S310). The cell monitoring device 30 estimates the capacity of each cell 11, 12, 13, 14 using the OCV of each cell 11, 12, 13, 14, and stores the capacity of each cell 11, 12, 13, 14 (S320).

[0041] The cell monitoring device 30 can estimate the capacity of each of the cells 11, 12, 13, and 14 from the OCV of each of the cells 11, 12, 13, and 14 using the OCV table. The OCV table can be a table that stores the capacity of each OCV. In the OCV table, the OCV can be subdivided in a set voltage unit. The cell monitoring device 30 can check the capacity corresponding to the OCV of each of the cells 11, 12, 13, and 14 from the OCV table. If the OCV of each of the cells 11, 12, 13, and 14 is not in the OCV table, the capacity of each of the cells 11, 12, 13, and 14 can be estimated using an interpolation method from two or more OCV values ​​in the OCV table and the capacity corresponding to each OCV value.

[0042] According to the embodiment, the cell monitoring device 30 can estimate the capacity of each cell 11, 12, 13, 14 more accurately by reflecting the current SOC (State of Health) of each cell 11, 12, 13, 14 in the estimated capacity using the OCV table.

[0043] The cell monitoring device 30 can calculate the consumption capacity of each of the cells 11, 12, 13, 14 based on the voltage of each of the cells 11, 12, 13, 14 in the discharging section and the charging section, and store the consumption capacity of each of the cells 11, 12, 13, 14 (S330).

[0044] The cell monitoring device 30 can calculate the amount of capacity reduction of each of the cells 11, 12, 13, 14 based on the capacity of each of the cells 11, 12, 13, 14 (S340). The cell monitoring device 30 can calculate the amount of capacity reduction of each of the cells 11, 12, 13, 14 from the difference between the capacity of each of the cells 11, 12, 13, 14 calculated in the pause section of the current cycle and the capacity of each of the cells 11, 12, 13, 14 calculated in the pause section of the previous cycle (S340). The cell monitoring device 30 can also calculate the amount of capacity reduction of each of the cells 11, 12, 13, 14 by reflecting the consumed capacity of each of the cells 11, 12, 13, 14 in the difference between the capacity of each of the cells 11, 12, 13, 14 calculated in the pause section of the current cycle and the capacity of each of the cells 11, 12, 13, 14 calculated in the pause section of the previous cycle (S340).

[0045] The cell monitoring device 30 compares the capacity loss of each cell 11, 12, 13, 14 with the average capacity loss of all the remaining cells excluding the cell 11, 12, 13, 14 in question, and can determine whether or not the cell 11, 12, 13, 14 is short-circuited based on the comparison result.

[0046] More specifically, the cell monitoring device 30 calculates the difference between the capacity loss of each cell 11, 12, 13, 14 and the average capacity loss of all remaining cells excluding the cells 11, 12, 13, 14 (S350), and compares the calculated difference with a set threshold value (S360).

[0047] If the calculated difference is greater than a threshold, the cell monitoring device 30 may determine that the cell is an internally shorted cell (S370). That is, the difference being greater than the threshold may mean that the capacity has decreased by more than the threshold.

[0048] On the other hand, if the calculated difference is equal to or less than the threshold, the cell monitoring device 30 can determine that the cell is a normal cell (S380).

[0049] To explain with one example, assume that the capacities of cells 11, 12, 13, and 14 calculated during the rest period of the previous cycle are 95 Ah, 100 Ah, 100 Ah, and 100 Ah, respectively, the capacities of cells 11, 12, 13, and 14 calculated during the rest period of the current cycle are 93 Ah, 101 Ah, 101 Ah, and 100 Ah, and the capacities of cells 11, 12, 13, and 14 consumed by cell balancing during the discharge and charge periods of the current cycle are -3 Ah, 0 Ah, 0 Ah, and 0 Ah, respectively. Below, the capacity loss of cell 11 is -4Ah (=93Ah-95Ah-3Ah), the capacity loss of cell 12 is 1Ah (=101Ah-100Ah-0Ah), the capacity loss of cell 13 is 1Ah (=101Ah-100Ah-0Ah), and the capacity loss of cell 14 is 0Ah (=100Ah-100Ah-0Ah). Here, the capacity loss having a negative (-) value means that the capacity has decreased.

[0050] To determine whether cell 11 is a shorted cell, the difference between the capacity loss of cell 11 and the average capacity loss of the remaining cells 12, 13, and 14 can be calculated. Assume that the threshold value to be compared to determine whether cell 11 is a shorted cell is set to -3 Ah. Since the capacity loss of cell 11 is -4 Ah and the average capacity loss of the remaining cells 12, 13, and 14 is 2 / 3 Ah, it can be determined that cell 11 has lost capacity by a value greater than the average capacity loss of the remaining cells 12, 13, and 14 by at least -3 Ah, and cell 11 can be determined to be shorted.

[0051] FIG. 4 is a diagram showing the capacitance of a normal cell and an internally shorted cell, and FIG. 5 is an enlarged diagram of a portion A shown in FIG.

[0052] 4 and 5, a shorted cell 11, which is internally shorted, has a continuously decreased capacity compared to normal cells 12, 13, and 14. Therefore, it is possible to detect an internally shorted cell by estimating the amount of capacity decrease of the cell.

[0053] Generally, to estimate the capacity loss of a cell, the charge / discharge capacity of the cell must be accurately calculated. However, it can be difficult to accurately calculate the charge / discharge capacity due to various factors such as the accuracy of the current sensor, efficiency due to temperature and charge / discharge rate, the self-discharge amount of the cell, and current consumption due to cell balancing.

[0054] On the other hand, the cell monitoring device 30 according to the embodiment can calculate the cell capacity reduction amount from the difference between the cell capacity estimated by the OCV in the previous pause section and the cell capacity estimated by the OCV in the current pause section.

[0055] In this way, by estimating the cell capacity using the OCV measured during the rest period, it is possible to eliminate the capacity calculation error rate caused by factors such as the accuracy of the current sensor, efficiency due to temperature and charge / discharge rate, the self-discharge amount of the cell, and current consumption due to cell balancing, thereby improving the accuracy of the capacity estimation.

[0056] Another method for determining whether a cell has an internal short circuit is a method of comparing voltages between cells. In the voltage comparison, the capacitance value relative to the voltage is different for each voltage section, and the capacitance standard corresponding to the threshold value is different for each voltage section, so that the short circuit resistance detected for each voltage section may be different. This is because the capacitance value that decreases depending on whether the voltage is detected in a certain voltage section is different, which affects the accuracy of detecting an internal short cell.

[0057] In contrast, the method of estimating the cell capacity using the OCV measured during the rest period does not require comparing the cell-to-cell voltages, and therefore can detect internally shorted cells more accurately than the cell-to-cell voltage comparison method.

[0058] FIG. 6 illustrates a cell monitoring device according to an embodiment.

[0059] 6, the cell monitoring device 30 may include an OCV calculation unit 32, a consumption capacity calculation unit 34, and a shorted cell detection unit 36. The cell monitoring device 30 may further include a storage unit 38. The cell monitoring device 30 may further include a switch control unit 39.

[0060] The OCV calculation unit 32 measures the OCV of each of the cells 11, 12, 13, and 14 during each idle period, and can estimate the capacity of each of the cells 11, 12, 13, and 14 using the measured OCV of each of the cells 11, 12, 13, and 14. The capacity of each of the cells 11, 12, 13, and 14 measured during each idle period is stored in the storage unit 38.

[0061] The consumption capacity calculation unit 34 can calculate the consumption capacity of each of the cells 11, 12, 13, and 14 in the discharging section and the charging section. The consumption capacity of each of the cells 11, 12, 13, and 14 calculated in the discharging section and the charging section is stored in the storage unit 38.

[0062] The shorted cell detection unit 36 ​​calculates the difference between the capacity of each of the cells 11, 12, 13, 14 calculated in two consecutive pause sections, i.e., the pause section of the t-th cycle, and the capacity of each of the cells 11, 12, 13, 14 calculated in the pause section of the (t-1)-th cycle, and can calculate the capacity reduction amount of each of the cells 11, 12, 13, 14 in the t-th cycle by reflecting the consumption capacity of each of the cells 11, 12, 13, 14 calculated in the discharge section and the charge section of the t-th cycle in the calculated difference. The shorted cell detection unit 36 ​​can calculate the difference between the capacity reduction amount of each of the cells 11, 12, 13, 14 in the t-th cycle and the average capacity reduction amount of the remaining cells excluding the shorted cell, and can determine a cell whose difference is equal to or greater than a set threshold as an internally shorted cell.

[0063] The switch control unit 39 may output a switch control signal (SCS) to the switch 20 to control opening or closing of the switch 20 in a pause period, a discharge period, and a charge period. The switch control unit 39 may output a switch control signal (SCS) to control opening of the switch 20 in a pause period. The switch control unit 39 may output a switch control signal (SCS) to control closing of the switch 20 in a discharge period and a charge period.

[0064] FIG. 7 is a diagram showing a cell monitoring device according to another embodiment.

[0065] Referring to FIG. 7, a cell monitoring device 700 may represent a computing device in which the above-described cell monitoring method is implemented.

[0066] The cell monitoring device 700 may include at least one of a processor 710, a memory 720, an input interface device 730, an output interface device 740, and a storage device 750. Each component may be connected to communicate with each other via a bus 760. Each component may also be connected to the processor 710 through individual interfaces or individual buses instead of the common bus 760.

[0067] The processor 710 may be implemented in various types such as an AP (Application Processor), a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), etc., and may be any semiconductor device that executes instructions stored in the memory 720 or the storage device 750. The processor 710 may execute program commands stored in at least one of the memory 720 and the storage device 750. The processor 710 may be configured to implement the functions and methods described with reference to FIGS. 1 to 6.

[0068] Memory 720 and storage device 750 may include various forms of volatile or non-volatile storage media. For example, memory 720 may include a read-only memory (ROM) 721 and a random access memory (RAM) 722. In some embodiments, memory 720 may be located internal or external to processor 710, and memory 720 may be connected to processor 710 through various means known in the art.

[0069] The input interface unit 730 may be configured to provide data to the processor 710 .

[0070] The output interface unit 740 may be configured to output data from the processor 710 .

[0071] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the claims also fall within the scope of the present invention. [Explanation of symbols]

[0072] 1 Battery Pack 10 Battery Module 11, 12, 13, 14 cells 20 Switch 30 Cell monitoring device 32 OCV calculation section 34 Consumption capacity calculation section 36 Shorted cell detection section 38 Preservation Department 39 Switch control section

Claims

1. A method for monitoring a plurality of cells in a battery module in a cell monitoring device, comprising: measuring an open circuit voltage of each of the plurality of cells during a first pause period; estimating a capacity of each of the plurality of cells using an open circuit voltage of each of the plurality of cells measured in the first rest period; measuring an open circuit voltage of each of the plurality of cells in a second pause interval following the first pause interval; estimating a capacity of each of the plurality of cells using an open circuit voltage of each of the plurality of cells measured during the second rest period; and A cell monitoring method comprising: detecting an internally shorted cell based on a capacity of each of the plurality of cells in the first rest period and a capacity of each of the plurality of cells in the second rest period.

2. The detecting step includes: calculating a capacity reduction amount of each of the plurality of cells based on a difference between a capacity of each of the plurality of cells in the first rest period and a capacity of each of the plurality of cells in the second rest period; and 2. The cell monitoring method according to claim 1, further comprising a step of comparing an amount of capacity loss of a first cell among the plurality of cells with an average amount of capacity loss of the remaining cells among the plurality of cells excluding the first cell to determine whether or not there is an internal short circuit in the first cell.

3. 3. The cell monitoring method of claim 2, wherein the determining step includes a step of determining that the first cell is an internally shorted cell when a difference between a capacity loss amount of the first cell and an average capacity loss amount of the remaining cells excluding the first cell is greater than a set threshold value.

4. The method further includes calculating a consumption capacity of each of the plurality of cells in a discharging section and a charging section, 3. The cell monitoring method according to claim 2, wherein the step of calculating the amount of capacity reduction for each of the plurality of cells includes a step of calculating the amount of capacity reduction for each of the plurality of cells by reflecting the consumed capacity of each of the plurality of cells in a difference between the capacity of each of the plurality of cells in the first pause interval and the capacity of each of the plurality of cells in the second pause interval.

5. The step of calculating a consumption capacity of each of the plurality of cells includes: connecting the battery module to a load during the discharging period; and The cell monitoring method according to claim 4 , further comprising the step of connecting the battery module to a charging device in the charging section.

6. The cell monitoring method according to claim 4 , wherein the step of measuring the open circuit voltage includes the step of cutting off a current supply to the battery module.

7. A cell monitoring device for managing a plurality of cells by setting a rest section, a discharge section, and a charge section in one operation cycle, an open circuit voltage calculation unit that measures an open circuit voltage of each of the plurality of cells during the rest period of each operation cycle and estimates a capacity of each of the plurality of cells using the open circuit voltage of each of the plurality of cells; a consumption capacity calculation unit for calculating a consumption capacity of each of the plurality of cells in the discharging section and the charging section of each operation cycle; and a cell monitoring device including: a shorted cell detection unit that calculates a capacity reduction amount of each of the plurality of cells based on a capacity of each of the plurality of cells and a consumption capacity of each of the plurality of cells in each operation cycle; and detects an internally shorted cell based on the capacity reduction amount of each of the plurality of cells.

8. The shorted cell detection unit is The cell monitoring device of claim 7, further comprising: a cell monitoring unit for monitoring a capacity of each of the plurality of cells; a cell monitoring unit for monitoring a capacity of each of the plurality of cells; a cell monitoring unit for monitoring a capacity of each of the plurality of cells;

9. 8. The cell monitoring device according to claim 7, wherein the short-circuited cell detection unit detects whether or not an internal short circuit exists in the first cell by comparing an amount of capacity reduction of a first cell among the plurality of cells with an average amount of capacity reduction of the remaining cells excluding the first cell.

10. 8. The cell monitoring device of claim 7, wherein the short-circuit cell detection unit determines that the first cell is an internally short-circuited cell when a difference between a capacity reduction amount of a first cell among the plurality of cells and an average capacity reduction amount of the remaining cells excluding the first cell is greater than a set threshold value.

11. 8. The cell monitoring device of claim 7, further comprising a switch control unit that disconnects a battery module including the plurality of cells from an external device in the pause section and connects the battery module to the external device in the discharge section and the charge section.

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