KR20230021999A - Method for detecting defective battery cell and battery management system providing the same - Google Patents

Abstract

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. The battery management system of the present invention relates to a battery including a plurality of battery cells As a battery management system (BMS) that detects defective battery cells,
A cell monitoring IC connected to both ends of each of a plurality of battery cells to measure a cell voltage of each of the plurality of battery cells, and a first charge in which the cell voltage first reaches a charge final voltage in a charging cycle. and a main control circuit for detecting a battery cell and detecting a first discharged battery cell whose cell voltage first reaches a discharge final voltage in a discharge cycle, wherein the main control circuit comprises: the first discharge battery cell; When the charged battery cell and the first discharged battery cell satisfy a first diagnosis condition indicating the same battery cell, the battery cell is detected as the defective battery cell.

Description

A method for detecting a defective battery cell and a battery management system providing the method

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.

An electric vehicle is a vehicle that operates with electric energy output from a battery composed of a predetermined number, for example, 2 to 4 batteries (battery pack). A battery may include a plurality of battery cells capable of being charged/discharged and may change its state depending on the external environment and its own characteristics. Accordingly, a battery management system (BMS) monitors and manages a plurality of battery cells included in a battery.

When each of the plurality of battery cells has performance within a predetermined range (hereinafter referred to as a battery cell within a normal range), the cell voltage of each of the plurality of battery cells fluctuates similarly within a predetermined range during a charge cycle and a discharge cycle. Therefore, even if the BMS terminates the charging cycle when a battery cell whose cell voltage reaches the charge final voltage is first generated, the battery can use all of its available battery capacity.

On the other hand, when a battery is used for a long period of time, a battery cell may degrade (deteriorate) and result in a battery cell (hereinafter referred to as a defective battery cell) out of performance within a predetermined range.

During a charge cycle or discharge cycle, the cell voltage of a defective battery cell will tend to reach its charge final voltage or discharge final voltage sooner than the cell voltage of a battery cell within the otherwise normal range. can Then, when the charging cycle is terminated when the cell voltage of the defective battery cell reaches the charging upper limit voltage, the charging of the battery cells in other normal categories may be terminated in a state that is not sufficiently charged. As a result, a problem arises in that the battery cannot use all available battery capacity.

Conversely, even if the cell voltage of the defective battery cell reaches the upper charging limit voltage, for battery capacity, if the defective battery cell continues to be charged until the cell voltage of the remaining battery cells reaches the upper charging limit voltage, the defective battery cell However, there is a problem in that the entire available capacity is repeatedly used, and deterioration is accelerated.

An object of the present invention is to provide a method for detecting a defective battery cell capable of detecting a defective battery cell deteriorating battery performance, and a battery management system providing the method.

A battery management system according to one 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, and is connected to both ends of each of the plurality of battery cells. A cell monitoring IC for measuring the cell voltage of each of the plurality of battery cells, and detecting a first charged battery cell whose cell voltage first reaches a charge final voltage in a charge cycle, and detecting a cell in a discharge cycle A first diagnosis condition for detecting a first discharged battery cell whose voltage reaches a discharge final voltage first, and indicating that the first charged battery cell and the first discharged battery cell are the same battery cell and a main control circuit for detecting the battery cell as the defective battery cell if satisfied.

The main control circuit determines between a first charging time when the first rechargeable battery cell is detected and a second charging time when a second rechargeable battery cell whose cell voltage reaches the charging upper limit voltage for the second time is detected in the charging cycle. A first bypass time, which is a time interval, is calculated, and a first discharge time point at which the first discharge battery cell is detected in the discharge cycle and a second discharge battery cell whose cell voltage reaches the discharge lower limit voltage for the second time is detected. A second bypass time, which is a time interval between the second discharge time points, is calculated, and when the first diagnosis condition and the second diagnosis condition are satisfied, the battery cell is detected as the defective battery cell, and the second diagnosis condition is , At least one of the first bypass time and the second bypass time may be greater than or equal to a predetermined reference time.

The battery system may further include a bypass circuit including a plurality of branch switches connected in parallel to each of the plurality of battery cells and electrically separating the parallel-connected battery cells from the battery in an on operation.

The main control circuit may control a branch switch connected in parallel to the first rechargeable battery cell to turn on when the first rechargeable battery cell is detected in the charging cycle.

The main control circuit may terminate the charging cycle when the second rechargeable battery cell is detected in the charging cycle.

The main control circuit may control a branch switch connected in parallel to the first discharge battery cell to be turned on when the first discharge battery cell is detected in the discharge cycle.

The main control circuit may terminate the discharge cycle when the second discharge battery cell is detected in the discharge cycle.

A method for detecting a defective battery cell according to another aspect 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, wherein in a charging cycle Detecting a first charged battery cell whose cell voltage reaches a charge final voltage first, and a first discharge whose cell voltage first reaches a discharge final voltage in a discharge cycle. Detecting a battery cell, determining whether the first charged battery cell and the first discharged battery cell satisfy a first diagnosis condition indicating the same battery cell, and if the first diagnosis condition is satisfied as a result of the determination , detecting the battery cell as the defective battery cell.

The detecting of the first rechargeable battery cell may include a first charging time point at which the first rechargeable battery cell is detected in the charging cycle and a second rechargeable battery cell whose cell voltage reaches the upper charging limit voltage for the second time in the charging cycle. Calculating a first bypass time, which is a time interval between detected second charging points, and checking the location of the first discharged battery cell may include a first discharge time point at which the first discharged battery cell is detected in the discharge cycle. Calculating a second bypass time, which is a time interval between a second discharge time point at which the second discharge battery cell whose cell voltage reaches the discharge lower limit voltage for the second time is detected, and determining whether the first diagnosis condition is satisfied In the step, it is further determined whether at least one of the first bypass time and the second bypass time satisfies a second diagnosis condition that is greater than or equal to a predetermined reference time, and the detecting as a defective battery cell comprises:

As a result of the determination, when the first diagnosis condition and the second diagnosis condition are satisfied, the battery cell may be detected as the defective battery cell.

The detecting of the first rechargeable battery cell may include controlling a branch switch connected in parallel to the first rechargeable battery cell to be turned on when the first rechargeable battery cell is generated, and a branch switch connected in parallel to the first rechargeable battery cell. may electrically separate the first rechargeable battery cell from the battery in an on operation.

In the detecting of the first rechargeable battery cell, the charging cycle may be terminated when the second rechargeable battery cell is generated.

The detecting of the first discharge battery cell may include controlling a branch switch connected in parallel to the first discharge battery cell to be turned on when the first discharge battery cell is generated, and a branch switch connected in parallel to the first discharge battery cell. may electrically separate the first discharged battery cell from the battery in an on operation.

In the detecting of the first discharged battery cell, the discharge cycle may be terminated when the second discharged battery cell is generated.

According to the present invention, a defective battery cell can be detected with high precision to increase battery stability and prevent battery performance from deteriorating.

According to the present invention, when a first charged battery cell and a first discharged battery cell are detected, acceleration of deterioration of the battery cell due to overcharging and overdischarging can be prevented by electrically separating the first charged battery cell and the first discharged battery cell from the battery. there is.

According to the present invention, a charge cycle and a discharge cycle are maintained until the second rechargeable battery cell and the second discharge battery cell are detected, so that each of the plurality of battery cells can be charged up to an available capacity range or the available capacity can be used.

1 is a diagram illustrating a battery system according to an exemplary embodiment.
2 is a flowchart illustrating a method of detecting a defective battery cell according to an exemplary embodiment.
3 is a flowchart illustrating a method of detecting a defective battery cell according to another embodiment.
FIG. 4 is a flowchart illustrating step S210 of FIG. 3 in detail.
5 is a flowchart illustrating step S230 of FIG. 3 in detail.

Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings, but the same or similar reference numerals are given to the same or similar components, and overlapping descriptions thereof will be omitted. The suffixes "module" and/or "unit" for components used in the following description are given or used interchangeably in consideration of ease of writing the specification, and do not themselves have a meaning or role distinct from each other. In addition, in describing the embodiments disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the embodiment disclosed in this specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, the technical idea disclosed in this specification is not limited by the accompanying drawings, and all changes included in the spirit and technical scope of the present invention , it should be understood to include equivalents or substitutes.

Terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

In this application, terms such as "comprise" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

1 is a diagram illustrating a battery system according to an exemplary embodiment.

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. do.

The battery 10 may include a plurality of battery cells (Cell1-Celln) electrically connected in series and parallel. In some embodiments, the battery cell may be a rechargeable secondary battery. A predetermined number of battery cells are connected in series to configure a battery module, a predetermined number of battery modules are connected in series to configure a battery pack, and a predetermined number of battery packs are connected in parallel to form a battery bank ( battery bank) to supply desired power. 1 shows a battery 10 in which a plurality of battery cells (Cell1-Celln) are connected in series, but is not limited thereto, and the battery 10 may be configured in units of battery modules, battery packs, or battery banks. .

Each of the plurality of battery cells (Cell1-Celln) is electrically connected to the BMS 40 through wires. The BMS 40 collects and analyzes various information about battery cells including information about a plurality of battery cells (Cell1-Celln) to control charging and discharging of the battery cells, protection operation, etc., and operation of the relay 30. can control.

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, and the battery system 1 A relay 30 is connected between the anode of the battery system 1 and the first output terminal OUT1, and a current sensor 20 is connected between the cathode of the battery system 1 and the second output terminal OUT2. The configurations shown in FIG. 1 and the connection relationship between the configurations are examples, but the invention is not limited thereto.

The current sensor 20 is connected in series to a current path between the battery 10 and an external device. The current sensor 20 may measure the battery current flowing through the battery 10, that is, the charging current and the discharging current, and transmit the measurement result to the BMS 40.

The relay 30 controls electrical connection between the battery system 1 and an external device. When the relay 30 is turned on, the battery system 1 and the external device are electrically connected to charge or discharge, and when the relay 30 is turned off, the battery system 1 and the external device are electrically separated. In this case, the external device may be an external charger in a charging cycle in which power is supplied to the battery 10 to be charged. Also, the external device may be a load in a discharge cycle in which power is discharged from the battery 10 .

The BMS 40 includes a bypass circuit 41 , a cell monitoring IC 43 and a main control circuit 45 .

The bypass circuit 41 may include a plurality of branch switches connected in parallel to each of the plurality of battery cells and electrically separating the battery cells connected in parallel from the battery 10 in an on operation.

Referring to FIG. 1 , when a branch switch is turned on in a charging cycle, power supplied to battery cells connected in parallel may be bypassed to other adjacent battery cells. When the branch switch is turned on in the discharge cycle, power may not be discharged from the battery cells connected in parallel. That is, when the branch switch is turned on, battery cells connected in parallel may be electrically separated from the battery 10 .

The cell monitoring IC 43 is electrically connected to an anode and a cathode of each of the plurality of battery cells Cell1 to Celln, and measures a cell voltage of each of the plurality of battery cells Cell1 to Celln. The battery current value measured by the current sensor 20 may be transmitted to the cell monitoring IC 43 . The cell monitoring IC 43 transfers information about the measured cell voltage and battery current to the main control circuit 45 . Specifically, the cell monitoring IC 43 measures the cell voltage of each of the plurality of battery cells (Cell1-Celln) every predetermined cycle during a rest period in which charging and discharging does not occur, and based on the measured cell voltage The cell current can be calculated. The cell monitoring IC 43 may transfer the cell voltage and cell current of each of the plurality of battery cells Cell1 to Celln to the main control circuit 45 .

The main control circuit 45 may detect a defective battery cell in the battery 10 including a plurality of battery cells based on a cell voltage of each of the plurality of battery cells Cell1 to Celln. More detailed information will be described with reference to FIGS. 2 to 4 below.

2 is a flowchart illustrating a method of detecting a defective battery cell according to an exemplary embodiment.

Hereinafter, the method described in FIG. 2 may include logic for the BMS 40 to detect a defective battery cell after each charge cycle and discharge cycle are performed once. According to one embodiment, the BMS 40 may detect a defective battery cell each time a charge cycle and a discharge cycle are performed once. In this case, the defective battery cell may be a battery cell whose performance is out of a predetermined range.

Referring to FIG. 2 , first, in a charging cycle in which the battery 10 is charged with power from an external device (eg, an external charger), the BMS 40 detects a first charged battery cell (S110).

The first rechargeable battery cell may indicate a battery cell whose cell voltage first reaches a charge final voltage (Vmax). The charging upper limit voltage (Vmax) may be a maximum voltage (Max Voltage) that can be charged in a range in which the battery cell is not dangerous. The capacity of the battery cell may increase as the charging upper limit voltage Vmax is higher, but overcharging may make the battery cell dangerous. Accordingly, the charging upper limit voltage Vmax may be appropriately set in consideration of battery cell capacity and stability.

Next, in a discharge cycle in which the discharged power of the battery 10 is supplied to an external device (eg, a load), the BMS 40 detects the first discharged battery cell (S130).

The first discharged battery cell may indicate a battery cell that first reaches a discharge final voltage (Vmin). The discharge lower limit voltage (Vmin) may be the lowest voltage (Min Voltage) at which the battery cell can be discharged in a non-hazardous range. As the discharge lower limit voltage (Vmin) is lowered, the capacity of the battery cell may increase, but overdischarge may make the battery cell dangerous. Accordingly, the discharge lower limit voltage Vmin may be appropriately set in consideration of battery cell capacity and stability.

Next, the BMS 40 determines whether the first diagnosis condition is satisfied (S150).

The first diagnosis condition may be that the first charged battery cell and the first discharged battery cell indicate the same battery cell.

Next, as a result of the determination, if the first diagnosis condition is satisfied (S150, Yes), the BMS 40 diagnoses that there is a defective battery cell among the plurality of battery cells (S170).

For example, it is assumed that among the five battery cells Cell1 , Cell2 , Cell3 , Cell4 , and Ce115 , a third battery cell Cell3 is detected as a first charged battery cell and a first discharged battery cell. The BMS 40 may detect the third battery cell Cell3 as a defective battery cell.

Next, as a result of the determination, if the first diagnosis condition is not satisfied (S150, No), the BMS 40 diagnoses that there is no defective battery cell among the plurality of battery cells (S190),

3 is a flowchart illustrating a method for detecting a defective battery cell according to another embodiment, FIG. 4 is a flowchart illustrating step S210 of FIG. 3 in detail, and FIG. 5 is a flowchart illustrating step S230 of FIG. 3 in detail. It is a flow chart.

Hereinafter, the method described with reference to FIG. 3 may include logic for the BMS 40 to detect a defective battery cell after each of a charge cycle and a discharge cycle are performed. According to one embodiment, the BMS 40 may detect a defective battery cell each time a charge cycle and a discharge cycle are performed once.

Referring to FIG. 3 , first, in a charging cycle in which the battery 10 is charged with power from an external device (eg, an external charger), the BMS 40 detects a first rechargeable battery cell and passes a first bypass. Time (ΔT1) is calculated (S210).

The first rechargeable battery cell may indicate a battery cell whose cell voltage first reaches a charge final voltage (Vmax). The charging upper limit voltage (Vmax) may be a maximum voltage (Max Voltage) that can be charged in a range in which the battery cell is not dangerous. The capacity of the battery cell may increase as the charging upper limit voltage Vmax is higher, but overcharging may make the battery cell dangerous. Accordingly, the charging upper limit voltage Vmax may be appropriately set in consideration of battery cell capacity and stability.

Referring to FIG. 4 , in step S210 , when the charging cycle starts, the BMS 40 determines whether to detect the first charged battery cell whose cell voltage first reaches the charge final voltage (Vmax). Do (S211, S212).

In step S210, when the first rechargeable battery cell is detected as a result of the determination (S212, Yes), the BMS 40 identifies a battery cell corresponding to the first rechargeable battery cell, and a branch switch connected in parallel to the first rechargeable battery cell Control to turn on (S213).

The branch switch connected in parallel to the first rechargeable battery cell may electrically separate the first rechargeable battery cell connected in parallel from the battery 10 in an on operation. Then, power supplied to the first rechargeable battery cell is bypassed to other adjacent battery cells, and the first rechargeable battery cell is overcharged until the cell voltage of the battery cells other than the first rechargeable battery cell reaches the charging upper limit voltage. can block it That is, acceleration of deterioration (deterioration) of the first rechargeable battery cell may be prevented.

In step S210, the BMS 40 determines whether to detect a second rechargeable battery cell whose cell voltage reaches the charging upper limit voltage Vmax secondly (S214).

Assume that the battery 10 includes five battery cells Cell1, Cell2, Cell3, Cell4, and Ce115, and a third battery cell Cell3 is detected as a first rechargeable battery cell. Then, the BMS 40 monitors the cell voltage of each of the first, second, fourth, and fifth battery cells (Cell1, Cell2, Cell4, and Ce115) excluding the third battery cell (Cell3), and Among the cell voltages of each of the 5 battery cells (Cell1, Cell2, Cell4, and Ce115), a battery cell that first reaches the charging upper limit voltage (Vmax) may be detected as a second rechargeable battery cell.

In step S210, if the second rechargeable battery cell is detected as a result of the determination (S214, Yes), the BMS 40 determines the first charging time point TC1 at which the first rechargeable battery cell is detected and the second rechargeable battery cell at which the second rechargeable battery cell is detected. The first bypass time (ΔT1 = TC2 - TC1), which is the time interval between the two charging points TC2, is calculated (S215).

In step S210, the BMS 40 ends the charging cycle (S216).

Assume that the third battery cell Cell3 is a defective battery cell, and the first, second, fourth, and fifth battery cells Cell1, Cell2, Cell4, and Ce115 are within normal ranges. Then, the cell voltage of each of the first, second, fourth, and fifth battery cells (Cell1, Cell2, Cell4, and Ce115) may increase or decrease equally within a predetermined error range. In this case, the defective battery cell may be a battery cell that does not have performance within a predetermined range due to deterioration (degeneration) or the like. A battery cell within a normal range may be a battery cell having performance within a predetermined range.

According to an embodiment, when one of the first, second, fourth, and fifth battery cells Cell1, Cell2, Cell4, and Ce115 is detected as the second rechargeable battery cell, even if the BMS 40 terminates the charging cycle, the first, Each of the 2, 4, and 5 battery cells (Cell1, Cell2, Cell4, and Ce115) may be in a charged state close to a usable capacity range. Then, acceleration of deterioration (deterioration) of the first rechargeable battery cell may be prevented, and the remaining battery cells may be charged to a usable capacity.

Next, in a discharge cycle in which the discharged power of the battery 10 is supplied to an external device (eg, a load), the BMS 40 detects the first discharged battery cell, and the second bypass time (ΔT2 ) is calculated (S230).

The first discharged battery cell may indicate a battery cell that first reaches a discharge final voltage (Vmin). The discharge lower limit voltage (Vmin) may be the lowest voltage (Min Voltage) at which the battery cell can be discharged in a non-hazardous range. As the discharge lower limit voltage (Vmin) is lowered, the capacity of the battery cell may increase, but overdischarge may make the battery cell dangerous. Accordingly, the discharge lower limit voltage Vmin may be appropriately set in consideration of battery cell capacity and stability.

Referring to FIG. 4 , when the discharge cycle starts in step S230 , the BMS 40 determines whether to detect the first discharge battery cell that first reaches the discharge lower limit voltage Vmin ( S231 and S232 ).

In step S230, when the first discharge battery cell is detected as a result of the determination (S232, Yes), the BMS 40 identifies a battery cell corresponding to the first discharge battery cell, and a branch switch connected in parallel to the first discharge battery cell Control to turn on (S233).

The branch switch connected in parallel to the first discharged battery cell may electrically separate the first discharged battery cell connected in parallel from the battery 10 in an on operation. Then, power is not discharged from the first discharged battery cell until the cell voltage of the battery cells other than the first discharged battery cell reaches the discharge lower limit voltage Vmin, thereby preventing the first discharged battery cell from being over-discharged. can Accordingly, acceleration of deterioration (deterioration) of the first discharged battery cell can be prevented.

In step S230, the BMS 40 determines whether to detect the second discharged battery cell whose cell voltage reaches the discharge lower limit voltage Vmin for the second time (S234).

Assume that the battery 10 includes five battery cells Cell1, Cell2, Cell3, Cell4, and Ce115, and a third battery cell Cell3 is detected as a first discharged battery cell. Then, the BMS 40 monitors the cell voltage of each of the first, second, fourth, and fifth battery cells (Cell1, Cell2, Cell4, and Ce115) excluding the third battery cell (Cell3), and Among the cell voltages of each of the 5 battery cells (Cell1, Cell2, Cell4, and Ce115), a battery cell that first reaches the discharge lower limit voltage (Vmin) may be detected as a second discharged battery cell.

In step S230, when the second discharge battery cell is detected as a result of the determination (S234, Yes), the BMS 40 determines the first discharge time point TD1 at which the first discharge battery cell is detected and the second discharge battery cell at which the second discharge battery cell is detected. A second bypass time (ΔT2 = TD2 - TD1), which is a time interval between two discharge points (TD2), is calculated (S235).

In step S230, the BMS 40 ends the discharge cycle (S236).

Assume that the third battery cell Cell3 is a defective battery cell, and the first, second, fourth, and fifth battery cells Cell1, Cell2, Cell4, and Ce115 are within normal ranges. Then, the cell voltage of each of the first, second, fourth, and fifth battery cells (Cell1, Cell2, Cell4, and Ce115) may increase or decrease equally within a predetermined error range.

According to an embodiment, when one of the first, second, fourth, and fifth battery cells Cell1, Cell2, Cell4, and Ce115 is detected as the second discharged battery cell, even if the BMS 40 terminates the discharge cycle, the first, Each of the 2, 4, and 5 battery cells (Cell1, Cell2, Cell4, and Ce115) can be discharged to a usable capacity range. Then, it is possible to prevent the deterioration (deterioration) of the first discharged battery cell from being accelerated, and the remaining battery cells can use all available capacities.

Next, the BMS 40 determines whether the first diagnosis condition and the second diagnosis condition are satisfied (S250).

Next, as a result of the determination, if the first diagnosis condition and the second diagnosis condition are satisfied (S250, Yes), the BMS 40 diagnoses that a defective battery cell among the plurality of battery cells exists (S270).

According to an embodiment, the first diagnosis condition may be that the first charged battery cell and the first discharged battery cell indicate the same battery cell. The second diagnosis condition may be a condition in which at least one of the first bypass time ΔT1 and the second bypass time ΔT2 is greater than or equal to a predetermined reference time Tth.

For example, it is assumed that among the five battery cells Cell1 , Cell2 , Cell3 , Cell4 , and Ce115 , a third battery cell Cell3 is detected as a first charged battery cell and a first discharged battery cell. Also, assume that the first bypass time ΔT1 and the second bypass time ΔT2 are greater than or equal to a predetermined reference time Tth. The BMS 40 may detect the third battery cell Cell3 as a defective battery cell.

For another example, it is assumed that a fourth battery cell Cell4 among five battery cells Cell1 , Cell2 , Cell3 , Cell4 , and Ce115 is detected as a first charged battery cell and a first discharged battery cell. Also, assume that the first bypass time ΔT1 or the second bypass time ΔT2 is greater than or equal to a predetermined reference time Tth. The BMS 40 may detect the fourth battery cell Cell4 as a defective battery cell.

Next, as a result of the determination, if the first diagnosis condition and the second diagnosis condition are not satisfied (S250, No), the BMS 40 diagnoses that there is no defective battery cell among the plurality of battery cells (S290),

According to an embodiment, assume that, for example, a third battery cell Cell3 among five battery cells Cell1, Cell2, Cell3, Cell4, and Ce115 is detected as a first charged battery cell and a first discharged battery cell. However, suppose that the first bypass time ΔT1 and the second bypass time ΔT2 are less than the predetermined reference time Tth. The BMS 40 may diagnose that a defective battery cell among a plurality of battery cells does not exist.

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 in the field to which the present invention belongs are also the rights of the present invention. belong to the range

Claims (13)

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 a plurality of battery cells to measure a cell voltage of each of the plurality of battery cells, and
Detect the first charged battery cell whose cell voltage reached the charge final voltage first in the charge cycle, and the first battery cell whose cell voltage first reached the discharge final voltage in the discharge cycle. A main control circuit that detects one discharged battery cell and detects the battery cell as the defective battery cell when the first charged battery cell and the first discharged battery cell satisfy a first diagnostic condition indicating that the first discharged battery cell is the same battery cell. Including, battery management system. According to claim 1,
The main control circuit,
A first bi which is a time interval between a first charging time when the first rechargeable battery cell is detected and a second charging time when a second rechargeable battery cell whose cell voltage reaches the charging upper limit voltage a second time is detected in the charging cycle. Calculate pass time,
A second discharge time interval between a first discharge point at which the first discharge battery cell is detected in the discharge cycle and a second discharge time point at which a second discharge battery cell whose cell voltage reaches the discharge lower limit voltage for the second time is detected Calculate pass time,
When the first diagnosis condition and the second diagnosis condition are satisfied, the battery cell is detected as the defective battery cell;
The second diagnosis condition,
The battery management system, characterized in that at least one of the first bypass time and the second bypass time is equal to or longer than a predetermined reference time. According to claim 2,
A bypass circuit including a plurality of branch switches connected in parallel to each of the plurality of battery cells and electrically isolating the parallel-connected battery cells from the battery in an on operation. According to claim 3,
The main control circuit,
Controlling a branch switch connected in parallel to the first rechargeable battery cell to be turned on when the first rechargeable battery cell is detected in the charging cycle. According to claim 4,
The main control circuit,
When the second rechargeable battery cell is detected in the charging cycle, the battery management system terminates the charging cycle. According to claim 3,
The main control circuit,
Controlling a branch switch connected in parallel to the first discharge battery cell to be turned on when the first discharge battery cell is detected in the discharge cycle. According to claim 6,
The main control circuit,
When the second discharged battery cell is detected in the discharge cycle, the battery management system terminates the discharge cycle. A method for a battery management system (BMS) to detect a defective battery cell in a battery including a plurality of battery cells, comprising:
Detecting a first charged battery cell whose cell voltage reaches a charge final voltage first in a charging cycle;
detecting a first discharged battery cell whose cell voltage reaches a discharge final voltage first in a discharge cycle;
Determining whether the first charged battery cell and the first discharged battery cell satisfy a first diagnosis condition indicating the same battery cell, and
and detecting the battery cell as the defective battery cell when the first diagnosis condition is satisfied as a result of the determination. According to claim 8,
The step of detecting the first rechargeable battery cell,
A first time interval between a first charging time when the first rechargeable battery cell is detected and a second charging time when a second rechargeable battery cell whose cell voltage reaches the charging upper limit voltage a second time is detected in the charging cycle. Calculate the bypass time,
The step of confirming the location of the first discharged battery cell,
A second time interval between a first discharge point at which the first discharge battery cell is detected in the discharge cycle and a second discharge time point at which a second discharge battery cell whose cell voltage reaches the discharge lower limit voltage for the second time is detected Calculate the bypass time,
Determining whether the first diagnosis condition is satisfied,
Further determining whether at least one of the first bypass time and the second bypass time satisfies a second diagnosis condition that is greater than or equal to a predetermined reference time,
The step of detecting the defective battery cell,
and detecting the battery cell as the defective battery cell when the first diagnosis condition and the second diagnosis condition are satisfied as a result of the determination. According to claim 9,
The step of detecting the first rechargeable battery cell,
Controlling a branch switch connected in parallel to the first rechargeable battery cell to turn on when the first rechargeable battery cell is generated;
A branch switch connected in parallel to the first rechargeable battery cell,
A method of detecting a defective battery cell, wherein an on operation electrically disconnects the first rechargeable battery cell from the battery. According to claim 10,
The step of detecting the first rechargeable battery cell,
terminating the charging cycle when the second rechargeable battery cell occurs. According to claim 9,
The step of detecting the first discharged battery cell,
controlling a branch switch connected in parallel to the first discharged battery cell to be turned on when the first discharged battery cell is generated;
A branch switch connected in parallel to the first discharged battery cell,
and electrically isolating the first discharged battery cell from the battery with an on operation. According to claim 12,
The step of detecting the first discharged battery cell,
terminating the discharge cycle when the second discharged battery cell occurs.

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