Method for Detecting Defective Battery Cells and Battery Management System Providing the Method

Abstract

To provide a method for detecting a defective battery cell among a plurality of battery cells constituting a battery, and to provide a battery management system providing the method.SOLUTION: A battery management system includes: a cell monitoring IC which is connected to both ends of a plurality of battery cells respectively, and measures a cell voltage of the plurality of battery cells respectively; and a main control circuit which detects a charged battery cell whose cell voltage is the first to reach a charge upper limit voltage among the plurality of battery cells, for each charge cycle of a battery, detects a discharged battery cell whose cell voltage is the first to reach a discharge lower limit voltage among the plurality of battery cells, for each discharge cycle of a battery, and detects, as a defective battery cell, a battery cell for which a total frequency obtained by adding a first frequency of being detected as a charged battery cell and a second frequency of being detected as a discharged battery cell, corresponds to a second reference frequency or more, when a sum of a charge cycle frequency and a discharge cycle frequency satisfies a first reference frequency.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Cross-reference to Related Applications This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0100431, filed on Jul. 30, 2021, and all contents disclosed in the document of the Korean Patent Application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a method for detecting a defective battery cell among a plurality of battery cells constituting a battery and a battery management system providing the method.

Background Art

[0003] An electric vehicle is a vehicle that operates on electrical energy output from a battery composed of a predetermined number of battery packs, for example, 2 to 4 battery packs. The battery includes a plurality of rechargeable battery cells, and may change its state depending on the external environment and its own characteristics. Therefore, a Battery Management System (BMS) monitors and manages the plurality of battery cells included in the battery.

[0004] When each of the plurality of battery cells has performance within a preset range (hereinafter, a battery cell within the normal range), the cell voltage of each of the plurality of battery cells varies similarly within a predetermined range during a charge cycle and a discharge cycle. Therefore, even if the BMS terminates the charge cycle when a battery cell whose cell voltage reaches the charge final voltage first occurs, the battery can use all of the available battery capacity.

[0005] On the one hand, when a battery is used for a long time, the battery cells may degenerate (deteriorate), and battery cells that deviate from the performance within the already set range (hereinafter referred to as defective battery cells) may occur. During the charge cycle or the discharge cycle, the cell voltage of the defective battery cell may exhibit the characteristic of reaching the charge final voltage or the discharge final voltage earlier than the cell voltages of other battery cells within the normal range.

[0006] When the charge cycle ends when the cell voltage of the defective battery cell reaches the charge final voltage, the other battery cells within the normal range may end the charge in an insufficiently charged state. As a result, the problem occurs that the battery cannot use all of its available battery capacity. In addition, there is a problem that the defective battery cell repeatedly uses the entire available capacity range, accelerating the degradation. Moreover, when a defect occurs in a battery cell, which is the basic unit constituting the battery, the overall voltage of the battery may drop, inducing frequent cell balancing and UV (Under Voltage) diagnosis and threatening the stability of the entire battery.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention provides a method for detecting a defective battery cell capable of detecting a defective battery cell that degrades the performance of a battery, and a battery management system that provides the method.

Means for Solving the Problems

[0008] A battery management system according to one aspect of the present invention is a Battery Management System (BMS) that detects a defective battery cell in a battery including a plurality of battery cells. The battery management system includes cell monitoring ICs connected to both ends of each of the plurality of battery cells to measure the cell voltage of each of the plurality of battery cells. And for each charge cycle of the battery, it detects the charging battery cell among the plurality of battery cells whose cell voltage first reaches the charge upper limit voltage. For each discharge cycle of the battery, it detects the discharging battery cell among the plurality of battery cells whose cell voltage first reaches the discharge lower limit voltage. If the total number of the charge cycle count and the discharge cycle count satisfies a first reference count, it detects as the defective battery cell a battery cell corresponding to a total count obtained by adding the first count detected as the charging battery cell and the second count detected as the discharging battery cell being equal to or more than a second reference count.

[0009] When the charging battery cell is detected, the main control circuit can end the charging cycle.

[0010] When the discharging battery cell is detected, the main control circuit can end the discharging cycle.

[0011] A battery management system according to another feature of the present invention is a battery management system (BMS) that detects a defective battery cell in a battery including a plurality of battery cells, a cell monitoring IC connected to both ends of each of the plurality of battery cells to measure the cell voltage of each of the plurality of battery cells, and for each charge cycle of the battery, detects a charging battery cell in which the cell voltage of the plurality of battery cells first reaches a charge upper limit voltage, and for each discharge cycle of the battery, detects a discharging battery cell in which the cell voltage of the plurality of battery cells first reaches a discharge lower limit voltage. If the total number of the charge cycles and the discharge cycles satisfies a first reference number of cycles, after being detected as the charging battery cell in the Nth charge cycle, a battery cell detected as the discharging battery cell in the (N + 1)th discharge cycle is detected as the defective battery cell, including a main control circuit.

[0012] After being detected as the discharging battery cell in the Nth discharge cycle, the main control circuit can detect a battery cell detected as the charging battery cell in the (N + 1)th charge cycle as the defective battery cell.

[0013] When the charging battery cell is detected, the main control circuit can end the charge cycle.

[0014] When the discharging battery cell is detected, the main control circuit can end the discharge cycle.

[0015] A method for detecting a defective battery cell according to another feature of the present invention is a method for a battery management system (BMS) to detect a defective battery cell in a battery including a plurality of battery cells. For each charge cycle of the battery, a step of detecting a charged battery cell whose cell voltage first reaches the charge upper limit voltage among the plurality of battery cells, for each discharge cycle of the battery, a step of detecting a discharged battery cell whose cell voltage first reaches the discharge lower limit voltage among the plurality of battery cells, a step of determining whether the total number of the charge cycle times and the discharge cycle times has reached a first reference number of times, and as a result of the determination, if it has reached, a step of detecting, as the defective battery cell, a battery cell corresponding to a total number of times obtained by adding the first number of times detected as the charged battery cell and the second number of times detected as the discharged battery cell being equal to or more than a second reference number of times.

[0016] The step of detecting the charged battery cell can end the charge cycle when the charged battery cell is detected.

[0017] The step of detecting the discharged battery cell can end the discharge cycle when the discharged battery cell is detected.

[0018] Another method for detecting a defective battery cell according to the features of the present invention is a method for a battery management system (BMS) to detect a defective battery cell in a battery including a plurality of battery cells. For each charging cycle of the battery, a step of detecting a charging battery cell among the plurality of battery cells whose cell voltage first reaches the charging upper limit voltage; for each discharging cycle of the battery, a step of detecting a discharging battery cell among the plurality of battery cells whose cell voltage first reaches the discharging lower limit voltage; a step of determining whether the total number of the charging cycles and the discharging cycles has reached a first reference number; and as a result of the determination, if it has reached, a step of detecting, as the defective battery cell, a battery cell that was detected as the charging battery cell in the Nth charging cycle and then detected as the discharging battery cell in the (N + 1)th discharging cycle.

[0019] The step of detecting as the defective battery cell can detect, as the defective battery cell, a battery cell that was detected as the charging battery cell in the (N + 1)th charging cycle after being detected as the discharging battery cell in the Nth discharging cycle.

[0020] The step of detecting the charging battery cell can end the charging cycle when the charging battery cell is detected.

[0021] The step of detecting the discharging battery cell can end the discharging cycle when the discharging battery cell is detected.

Advantages of the Invention

[0022] The present invention can quickly and highly precisely detect a defective battery cell, improve the stability of the battery, and prevent the performance of the battery from degrading.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Best Mode for Carrying Out the Invention

[0024] Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings. The same or similar reference numerals are assigned to the same or similar components, and duplicate descriptions thereof are omitted. The suffixes "module" and / or "section" for the components used in the following description are given or mixed only for the ease of preparing the specification, and do not have meanings or roles that are distinguishable from each other by themselves. Further, when it is determined that a specific description of a known technique related to the description of the embodiments disclosed in this specification may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof is omitted. Further, the accompanying drawings are only for facilitating the understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the accompanying drawings, and it should be understood to include all modifications, equivalents, and alternatives included in the idea and technical scope of the present invention.

[0025] Terms including ordinal numbers such as first, second, etc. can be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

[0026] When it is mentioned that a certain component is "connected to" or "attached to" another component, it should be understood that it may be directly connected or attached to the other component, but there may also be other components in between. On the contrary, when it is mentioned that a certain component is "directly connected to" or "directly attached to" another component, it should be understood that there are no other components in between.

[0027] In this application, terms such as "comprising" or "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and it should be understood that they do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof in advance.

[0028] FIG. 1 is a diagram for explaining a battery system according to an embodiment.

[0029] Referring to FIG. 1, the battery system 1 includes a battery 10, a current sensor 20, a relay 30, and a battery management system (hereinafter referred to as 'BMS') 40.

[0030] The battery 10 can include a plurality of battery cells Cell1-Celln that are electrically connected in series and in parallel. In one embodiment, the battery cells may be rechargeable secondary batteries. A predetermined number of battery cells are connected in series to form a battery module, a predetermined number of battery modules are connected in series to form a battery pack, and a predetermined number of battery packs are connected in parallel to form a battery bank, which can supply a desired amount of power. Although FIG. 1 shows a battery 10 in which a plurality of battery cells Cell1-Celln are connected in series, the battery 10 is not limited thereto and can be configured in units of a battery module, a battery pack, or a battery bank.

[0031] Each of the plurality of battery cells Cell1-Celln is electrically connected to the BMS 40 through wiring. The BMS 40 can collect and analyze various information regarding the battery cells, including information regarding the plurality of battery cells Cell1-Celln, to control the charging, discharging, and protection operations of the battery cells and to control the operation of the relay 30.

[0032] In FIG. 1, the battery 10 includes a plurality of battery cells Cell1-Celln connected in series and is connected between two output terminals OUT1 and OUT2 of the battery system 1. A relay 30 is connected between the positive electrode of the battery system 1 and the first output terminal OUT1, and a current sensor 20 is connected between the negative electrode of the battery system 1 and the second output terminal OUT2. The configuration shown in FIG. 1 and the connection relationships between the configurations are examples, and the invention is not limited thereto.

[0033] The current sensor 20 is connected in series to the current path between the battery 10 and an external device. The current sensor 20 can measure the battery current flowing through the battery 10, i.e., the charging current and the discharging current, and transmit the measurement results to the BMS 40.

[0034] Relay 30 controls the electrical connection between the battery system 1 and the external device. When relay 30 is turned on, the battery system 1 and the external device are electrically connected and charging or discharging occurs. When relay 30 is turned off, the battery system 1 and the external device are electrically separated. At this time, the external device may be a charger that supplies power to the battery 10 for charging in a charging cycle, or a load in a discharging cycle where the battery 10 discharges power to the external device.

[0035] BMS 40 includes a cell monitoring IC 41 and a main control circuit 43.

[0036] The cell monitoring IC 41 is electrically connected to the positive and negative electrodes of each of the plurality of battery cells Cell1 - Celln to measure the cell voltage of each of the plurality of battery cells Cell1 - Celln. The battery current value measured by the current sensor 20 is transmitted to the cell monitoring IC 41. The cell monitoring IC 41 transmits information regarding the measured cell voltage and battery current to the main control circuit 43. Specifically, the cell monitoring IC 41 measures the cell voltage of each of the plurality of battery cells Cell1 - Celln at a predetermined period during a rest period when charging and discharging do not occur, and can calculate the cell current based on the measured cell voltage. The cell monitoring IC 41 can transmit the cell voltage and cell current of each of the plurality of battery cells Cell1 - Celln to the main control circuit 43.

[0037] The main control circuit 43 can detect a defective battery cell based on the charged battery cell and the discharged battery cell if the number of charge / discharge cycles satisfies a first reference number of cycles.

[0038] The charged battery cell can indicate the battery cell whose cell voltage first reaches the charge final voltage in the charging cycle. The discharged battery cell can indicate the discharged battery cell whose cell voltage first reaches the discharge final voltage in the discharging cycle. For example, the main control circuit 43 can use the electrical position of the battery cell in the battery 10 as an identification factor of the battery cell.

[0039] FIG. 2 is a flowchart for explaining a method for detecting a defective battery cell according to an embodiment.

[0040] Hereinafter, with reference to FIGS. 1 and 2, a method for detecting a defective battery cell according to an embodiment and a battery management system providing the method will be described in detail.

[0041] First, for each charging cycle in which the BMS 40 charges the battery 10 with the power of an external device, the charged battery cell whose cell voltage first reaches the charge final voltage (Vmax) among the plurality of battery cells Cell1-Celln is detected (S110).

[0042] The charge final voltage (Vmax) may be the maximum voltage (Max Voltage) at which the battery 10 can be charged within a safe range. The higher the charge final voltage (Vmax), the greater the capacity of the battery 10 can be increased, but overcharging may endanger the battery 10. Therefore, the charge final voltage can be appropriately set in consideration of the capacity and stability of the battery 10.

[0043] BMS40 can use the electrical position of a battery cell as an identification factor for the battery cell. For example, in the Nth charging cycle, BMS40 checks the electrical position of the battery cell among the plurality of battery cells Cell1 - Celln whose cell voltage first reaches the charging upper limit voltage (Vmax), and can add one detection count to the battery cell at that position.

[0044] When a charged battery cell is detected, BMS40 can end the charging cycle. By doing so, it can prevent the overcharge state in which the charged battery cell continues to be charged until the cell voltages of the remaining battery cells except the charged battery cell reach the charging upper limit voltage (Vmax), and prevent the degradation (deterioration) of the charged battery cell from accelerating.

[0045] Next, in the discharge cycle in which BMS40 supplies the discharged power of battery 10 to an external device, it detects the discharged battery cell whose cell voltage first reaches the discharge lower limit voltage (discharge final voltage, Vmin) (S120).

[0046] The discharge lower limit voltage (Vmin) may be the minimum voltage (Min Voltage) at which battery 10 can be discharged within a safe range. The lower the discharge lower limit voltage (Vmin), the more the capacity of battery 10 can increase, but over-discharge may endanger battery 10. Therefore, the discharge lower limit voltage (Vmin) is appropriately set considering the capacity and stability of battery 10. For example, the discharge lower limit voltage can be referred to as the cut-off voltage.

[0047] BMS40 can use the electrical position of a battery cell in battery 10 as an identification factor for the battery cell. For example, in the Nth discharge cycle, BMS40 checks the position of the battery cell among the plurality of battery cells Cell1 - Celln whose cell voltage first reaches the discharge lower limit voltage (Vmin), and can add one detection count to the battery cell at that position.

[0048] When the discharge battery cell is detected, the BMS 40 can end the discharge cycle. By doing so, it can cut off the over-discharge state in which the discharge battery cell continues to discharge until the cell voltage of the remaining battery cells excluding the discharge battery cell reaches the lower discharge voltage limit, and prevent the degradation (deterioration) of the discharge battery cell from accelerating.

[0049] Next, the BMS 40 determines whether the total number of charge cycles and discharge cycles satisfies a first reference number (S130).

[0050] The first reference number can correspond to the optimal number of charge-discharge cycles for detecting a defective battery cell. For example, the first reference number can be derived by a predetermined experiment.

[0051] If the result of the determination is that the total number of charge-discharge cycles does not satisfy the first reference number (S130, No), the BMS 40 repeats from step S110.

[0052] If the result of the determination is that the total number of charge-discharge cycles satisfies the first reference number (S130, Yes), the BMS 40 determines whether there is a battery cell whose total number obtained by adding the first number detected as the charge battery cell and the second number detected as the discharge battery cell is equal to or greater than a second reference number (S140).

[0053] For example, assume that battery 10 includes five battery cells, Cell1, Cell2, Cell3, Cell4, and Cell5, and the first reference number is 500 times and the second reference number is 300 times. If the third battery cell is detected a total of 400 times (for example, detected 200 times as the charge battery cell and 200 times as the discharge battery cell), and each of the first, second, fourth, and fifth battery cells is detected a total of 25 times (for example, detected 12 times as the charge battery cell and 13 times as the discharge battery cell), the BMS 40 can determine that there is a battery cell corresponding to 2 or more reference numbers.

[0054] Next, if as a result of the determination, there is a battery cell corresponding to a total number of times greater than or equal to the second reference number of times (S140, Yes), the BMS 40 diagnoses that there is a defective battery cell among the plurality of battery cells (S150).

[0055] For example, the BMS 40 can detect the third battery cell Cell3 corresponding to a total number of times greater than or equal to the second reference number of times as a defective battery cell. Depending on the embodiment, the defective battery cell may be a battery cell in which the battery cell has deteriorated (degraded) and deviated from the performance within the already set range.

[0056] Next, if as a result of the determination, there is no battery cell corresponding to a total number of times greater than or equal to the second reference number of times (S140, No), the BMS 40 diagnoses that there is no defective battery cell among the plurality of battery cells (S160).

[0057] FIG. 3 is a flowchart for explaining a method for detecting a defective battery cell according to another embodiment.

[0058] Hereinafter, with reference to FIGS. 1 and 3, a method for detecting a defective battery cell according to another embodiment and a battery management system providing the method will be described in detail.

[0059] First, the BMS 40 detects a charging battery cell in which the cell voltage first reaches the charging upper limit voltage (charge final voltage, Vmax) in a charging cycle for charging the battery 10 with the power of an external device (S210).

[0060] The charging upper limit voltage (Vmax) may be the maximum voltage (Max Voltage) at which the battery 10 can be charged within a safe range. The higher the charging upper limit voltage (Vmax), the greater the capacity of the battery 10 can be increased, but overcharging may endanger the battery 10. Therefore, the charging upper limit voltage can be appropriately set considering the capacity and stability of the battery 10.

[0061] The BMS 40 can use the electrical position of the battery cell as an identification factor for the battery cell. For example, in the Nth charging cycle, the BMS 40 checks the electrical position of the battery cell among the plurality of battery cells Cell1 - Celln whose cell voltage first reaches the charging upper limit voltage (Vmax), and can add one detection count to the battery cell at that position.

[0062] When a charged battery cell is detected, the BMS 40 can end the charging cycle. By doing so, it can prevent the overcharging state where the charged battery cell continues to be charged until the cell voltages of the remaining battery cells except the charged battery cell reach the charging upper limit voltage (Vmax), and prevent the acceleration of the degradation of the charged battery cell.

[0063] Next, in the discharge cycle where the BMS 40 supplies the discharged power of the battery 10 to an external device, the BMS 40 detects the discharged battery cell whose cell voltage first reaches the discharge lower limit voltage (discharge final voltage, Vmin) (S220).

[0064] The discharge lower limit voltage (Vmin) may be the minimum voltage (Min Voltage) at which the battery 10 can be discharged within a safe range. The lower the discharge lower limit voltage (Vmin), the greater the capacity of the battery 10 can be increased, but overdischarging may endanger the battery 10. Therefore, the discharge lower limit voltage (Vmin) can be appropriately set considering the capacity and stability of the battery 10. For example, the discharge lower limit voltage can be referred to as the cut-off voltage.

[0065] The BMS 40 can use the electrical position of the battery cell in the battery 10 as an identification factor for the battery cell. For example, in the Nth discharge cycle, the BMS 40 checks the electrical position of the battery cell among the plurality of battery cells Cell1-Celln whose cell voltage first reaches the discharge lower limit voltage (Vmin), and can add 1 to the detection count for the battery cell at that position.

[0066] When a discharged battery cell is detected, the BMS 40 can end the discharge cycle. By doing so, it can cut off the over-discharge state in which the discharged battery cell continues to discharge until the cell voltages of the remaining battery cells except the discharged battery cell reach the discharge lower limit voltage, and prevent the degradation (deterioration) of the discharged battery cell from accelerating.

[0067] Next, the BMS 40 determines whether the total number of charge cycles and discharge cycles satisfies a first reference number of cycles (S230).

[0068] The first reference number of cycles can correspond to the optimal number of charge and discharge cycles for detecting a defective battery cell. For example, the first reference number of cycles can be derived by a predetermined experiment.

[0069] If the result of the determination is that the total number of charge and discharge cycles does not satisfy the first reference number of cycles (S230, No), the BMS 40 repeats from step S210.

[0070] If the result of the determination is that the total number of charge and discharge cycles satisfies the first reference number of cycles (S230, Yes), the BMS 40 determines whether the charging battery cell and the discharging battery cell continuously correspond to the same battery cell (S240).

[0071] According to one embodiment, if there is a battery cell that is detected as a charging battery cell in the Nth charging cycle and then detected as a discharging battery cell in the (N + 1)th discharging cycle, the BMS 40 can determine that the charging battery cell and the discharging battery cell correspond to the same battery cell continuously.

[0072] According to another embodiment, if there is a charging battery cell in the (N + 1)th charging cycle after a battery cell is detected as a discharging battery cell in the Nth discharging cycle, the BMS 40 can determine that the charging battery cell and the discharging battery cell correspond to the same battery cell continuously.

[0073] Suppose the battery 10 includes five battery cells Cell1, Cell2, Cell3, Cell4, and Cell5, and the first reference number of times is 500. For example, if the fourth battery cell Cell4 is detected as a charging battery cell in the 35th charging cycle and then detected as a discharging battery cell in the 36th discharging cycle, the BMS 40 can determine that the charging battery cell and the discharging battery cell correspond to the same battery cell continuously. Another example is that if the fifth battery cell Cell5 is detected as a discharging battery cell in the 37th discharging cycle and then detected as a charging battery cell in the 38th charging cycle, the BMS 40 can determine that the charging battery cell and the discharging battery cell correspond to the same battery cell continuously.

[0074] Next, as a result of the determination, if the charging battery cell and the discharging battery cell correspond to the same battery cell continuously (S240, Yes), the BMS 40 diagnoses that there is a defective battery cell among the plurality of battery cells (S250).

[0075] For example, after being detected as a charged battery cell in the 35th charging cycle, the BMS 40 can detect the fourth battery cell Cell4, which was detected as a discharged battery cell in the 36th discharging cycle, as a defective battery cell. As another example, after being detected as a discharged battery cell in the 37th discharging cycle, the BMS 40 can detect the fifth battery cell Cell5, which was detected as a charged battery cell in the 38th charging cycle, as a defective battery cell. According to an embodiment, the defective battery cell may be a battery cell corresponding to a case where the battery cell has deteriorated and has fallen below a preset performance level.

[0076] Next, as a result of the determination, if the charged battery cell and the discharged battery cell do not continuously correspond to the same battery cell (S240, No), the BMS 40 diagnoses that there is no defective battery cell among the plurality of battery cells (S260).

[0077] Although the embodiments of the present invention have been described in detail above, the scope of the rights of the present invention is not limited thereto, and forms variously modified and improved by those having ordinary knowledge in the field to which the present invention pertains also belong to the scope of the rights of the present invention.

Claims

1. A battery management system (BMS) for detecting a defective battery cell in a battery including a plurality of battery cells, comprising: a cell monitoring IC connected to both ends of each of the plurality of battery cells to measure a cell voltage of each of the plurality of battery cells; a main control circuit that detects a charging battery cell whose cell voltage has reached an upper charging limit voltage among the plurality of battery cells in a charging cycle of the battery, and detects a discharging battery cell whose cell voltage has reached a lower discharging limit voltage among the plurality of battery cells in a discharging cycle of the battery, and detects a battery cell whose total number of times, obtained by adding together a first number of times that the battery cell has been detected as the charging battery cell and a second number of times that the battery cell has been detected as the discharging battery cell, is equal to or greater than a second reference number, as the defective battery cell.

2. The main control circuit includes: The battery management system of claim 1 , further comprising: terminating the charging cycle when the charging battery cell is detected.

3. The main control circuit includes: The battery management system of claim 1 or 2, further comprising: terminating the discharge cycle when the discharged battery cell is detected.

4. A battery management system (BMS) for detecting a defective battery cell in a battery including a plurality of battery cells, comprising: a cell monitoring IC connected to both ends of each of the plurality of battery cells to measure a cell voltage of each of the plurality of battery cells; a main control circuit that detects a charging battery cell, the cell voltage of which among the plurality of battery cells has reached an upper charging voltage, during a charging cycle of the battery, and detects a discharging battery cell, the cell voltage of which among the plurality of battery cells has reached a lower discharging voltage, during a discharging cycle of the battery, and detects a battery cell that has been detected as the charging battery cell in an N-th charging cycle and then detected as the discharging battery cell in an N+1-th discharging cycle as the defective battery cell.

5. The main control circuit includes: The battery management system of claim 4 , further comprising: detecting, as the defective battery cell, a battery cell that is detected as the discharged battery cell in an Nth discharge cycle and then detected as the charged battery cell in an (N+1)th charge cycle.

6. The main control circuit includes: The battery management system of claim 4 , further comprising: terminating the charging cycle when the charging battery cell is detected.

7. The main control circuit includes: The battery management system of claim 4 , further comprising: terminating the discharge cycle when a discharged battery cell is detected.

8. A method for detecting a defective battery cell in a battery including a plurality of battery cells by a battery management system (BMS), comprising: Detecting a charging battery cell whose cell voltage has reached a charging upper limit voltage among the plurality of battery cells in a charging cycle of the battery; Detecting a discharged battery cell whose cell voltage has reached a lower limit voltage among the plurality of battery cells in a discharge cycle of the battery; detecting, as the defective battery cell, a battery cell whose total number of times obtained by adding together the first number of times detected as the charged battery cell and the second number of times detected as the discharged battery cell corresponds to a second reference number or more.

9. The step of detecting a charging battery cell comprises:

9. The method of claim 8, further comprising terminating the charging cycle when the charging battery cell is detected.

10. The step of detecting the discharged battery cell comprises:

10. The method for detecting defective battery cells according to claim 8 or 9, further comprising terminating the discharge cycle when the discharged battery cell is detected.

11. A method for detecting a defective battery cell in a battery including a plurality of battery cells by a battery management system (BMS), comprising: Detecting a charging battery cell whose cell voltage has reached a charging upper limit voltage among the plurality of battery cells in a charging cycle of the battery; Detecting a discharged battery cell whose cell voltage has reached a lower limit voltage among the plurality of battery cells in a discharge cycle of the battery; detecting a battery cell that is detected as the charged battery cell in an Nth charge cycle and then detected as the discharged battery cell in an (N+1)th discharge cycle as the defective battery cell.

12. The step of detecting a defective battery cell includes:

12. The method for detecting a defective battery cell of claim 11, further comprising detecting a battery cell that is detected as the discharged battery cell in an Nth discharge cycle and then detected as the charged battery cell in an N+1th charge cycle as the defective battery cell.

13. The step of detecting a charging battery cell comprises:

12. The method of claim 11, further comprising terminating the charging cycle when the charging battery cell is detected.

14. The step of detecting the discharged battery cell comprises:

14. The method of detecting defective battery cells according to any one of claims 11 to 13, further comprising terminating the discharge cycle when the discharged battery cell is detected.

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