Patent Description:
Recently, research and development on a secondary battery are being actively conducted. Here, the secondary battery is a battery capable of charging and discharging, and is meant to include all of a conventional Ni/Cd battery, Ni/MH battery, etc. and a recent lithium ion battery. Among the secondary batteries, the lithium ion battery has an advantage of having much higher energy density compared to the conventional Ni/Cd battery, Ni/MH battery, etc. In addition, the lithium ion battery can be manufactured in a small size and light weight, and thus the lithium ion battery is used as a power source for a mobile device. In addition, the lithium ion battery is attracting attention as a nextgeneration energy storage medium as its range of use has been expanded to a power source for an electric vehicle.

In addition, the secondary battery is generally used as a battery pack including a battery module in which a plurality of battery cells are connected in series and/or in parallel. In addition, a state and operation of the battery pack are managed and controlled by a battery management system (BMS).

In particular, in an energy storage system (ESS) field, when a short circuit occurs inside a cell of a battery module, it may damage not only the battery but also the entire ESS system. However, conventionally, there has been no method capable of early detection of an internal short circuit of the battery cell.

In addition, conventionally, by measuring a voltage across each cell in the battery module in real time, detection has been performed only on a portion outside the operating range such as low voltage or high voltage. Therefore, in the conventional ESS system, detection of an abnormality in cell voltage behavior due to an instantaneous internal short circuit of a battery cell has not been achieved.

An example of an abnormality detection in a battery voltage behavior can be found for instance in <CIT>, <CIT> or <CIT>.

The present invention has been made to solve the problems described above, and an object thereof is to provide an apparatus and method for diagnosing a battery cell which are capable of detecting an abnormality in cell voltage behavior due to an instantaneous internal short circuit of the battery cell.

The present disclosure provides an apparatus for diagnosing a battery module comprising battery cells as defined by the independent claim <NUM> and a method for diagnosing the battery module comprising battery cells as defined by the independent claim <NUM>. Preferred embodiments are defined in the appended dependent claims. The apparatus for diagnosing a battery cell includes a voltage measurement unit that measures a voltage of each battery cell of a battery module in a state of an open circuit voltage of a battery, a state of charge (SOC) calculation unit adapted to calculate SOC of each battery cell of the battery module based on the measured voltage, a memory that stores the measured voltage and the calculated SOC at predetermined time intervals, and an abnormality detection unit that compares a current measured voltage and the SOC calculated based on the current measured voltage with a measured voltage and the SOC calculated based on the current measured voltage before a preset time for each battery cell of the battery module and determines that an abnormality has occurred in the battery cell when an absolute value of difference between the current measured voltage and the measured voltage before the preset time exceeds a first reference value and an absolute value of difference between the SOC calculated from current measured voltage and the SOC calculated measured voltage before the preset time exceeds a second reference value.

In the apparatus , the preset time may be <NUM> seconds.

The abnormality detection unit may perform abnormality diagnosis of the battery cell when a state in which the current flowing through the battery module is <NUM> continues for <NUM> seconds or more, and a state of charge (SOC) of the battery cell is equal to or greater than a preset numerical value.

The abnormality detection unit may perform an abnormality diagnosis of the battery cell when <NUM> seconds have elapsed from a time point when charging or discharging of the battery is finished and the current flowing through the battery module is <NUM>.

In the apparatus, the preset numerical value of the SOC may be <NUM>%.

In the apparatus, a difference between the current measured voltage and the measured voltage before the preset time may include both a voltage drop amount and a voltage rise amount of the battery cell.

The abnormality detection unit may determine that an abnormality has occurred in the battery cell when the state in which the difference between the current measured voltage and the measured voltage before the preset time exceeds the first reference value occurs two or more times in succession.

In the apparatus, the reference value may be <NUM> mV.

The method for diagnosing a battery module comprising battery cells includes measuring a voltage of each battery cell of a battery module in a state of an open circuit voltage of a battery, calculating a state of charge (SOC) of each battery cell of the battery module based on the measured voltage, storing the measured voltage and the calculated SOC based on the current measured voltage at predetermined time intervals, comparing a current measured voltage and the SOC calculated based on the current measured voltage with a measured voltage before a preset time for each battery cell and the SOC calculated based on the measured voltage before the preset time for each battery cell, and determining that an abnormality has occurred in the battery cell when an absolute value of difference between the current measured voltage and the measured voltage before the preset time exceeds a first reference value and an absolute value of difference between the SOC calculated from current measured voltage and the SOC calculated measured voltage before the preset time exceeds a second reference value.

In the method , the preset time may be <NUM> seconds.

The method further includes, before the comparing the current measured voltage with the measured voltage before the preset time for each battery cell, measuring a current flowing through the battery module and an SOC of the battery cell, in which comparing the current measured voltage and the measured voltage before the preset time may be performed when a state in which the current flowing through the battery module is <NUM> continues for <NUM> seconds or more and a state of charge (SOC) of the battery cell is equal to or greater than a preset numerical value, in the measuring the current flowing through the battery module and the SOC of the battery cell.

The method further includes, before the comparing the current measured voltage with the measured voltage before the preset time for each battery cell, measuring a current flowing through the battery module, in which the comparing the current measured voltage with the measured voltage before the preset time for each battery cell may be performed when <NUM> seconds have elapsed from a time point when charging or discharging of the battery is finished and the current flowing through the battery module is <NUM> in the measuring the current flowing through the battery module.

In the method, the preset numerical value of the SOC may be <NUM>%.

In the method, the difference between the current measured voltage and the measured voltage before the preset time may include both a voltage drop amount and a voltage rise amount of the battery cell.

In the method, it may be determined that an abnormality has occurred in the battery cell when a case in which the difference between the current measured voltage and the measured voltage before the preset time exceeds the first reference value occurs two or more times in succession, in the determining that the abnormality has occurred in the battery cell.

According to an apparatus and method for diagnosing a battery module comprising battery cells, an abnormality in cell voltage behavior due to an instantaneous internal short circuit of the battery cell can be detected early.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this document, the same reference numerals are used for the same constituent elements in the drawings, and duplicate descriptions for the same constituent elements are omitted.

With respect to the various embodiments of the present invention disclosed in this document, specific structural or functional descriptions have been exemplified for the purpose of describing the embodiments of the present invention only, and various embodiments of the present invention can be embodied in various forms and should not be construed as being limited to the embodiments described in this document.

Expressions such as "first", "second", "firstly", or "secondly", etc. used in various embodiments can modify various constituent elements regardless of order and/or importance, and does not limit corresponding constituent elements. For example, without departing from the scope of the present invention, a first constituent element can be named as a second constituent element, and similarly, the second constituent element can also be named as the first constituent element.

The terms used in this document are only used to describe a specific embodiment, and may not be intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise.

All terms used herein, including technical or scientific terms, may have the same meaning as generally understood by a person of ordinary skill in the art. Terms defined in a generally used dictionary may be interpreted as having the same or similar meaning as the meaning in the context of the related technology, and are not to be interpreted as an ideal or excessively formal meaning unless explicitly defined in this document. In some cases, even terms defined in this document cannot be interpreted to exclude embodiments of the present invention.

<FIG> is a block diagram illustrating a configuration of a battery control system. Referring to <FIG>, a configuration diagram schematically illustrating a battery control system including a battery pack <NUM> and an upper-level controller <NUM> included in an upper-level system according to an embodiment of the present invention is illustrated.

As illustrated in <FIG>, the battery pack <NUM> includes a battery module <NUM> composed of one or more battery cells and capable of charging and discharging, a switching unit <NUM> connected in series to the +terminal side or the -terminal side of the battery module <NUM> to control a charge/discharge current flow of the battery module <NUM>, and a battery management system <NUM> that monitors the voltage, current, temperature, etc. of the battery module <NUM> and controls and manages to prevent overcharging and overdischarging. Here, although the battery management system <NUM> is described as being connected to the battery module, the battery management system <NUM> may also be connected to each battery cell to monitor and measure the voltage and current temperature of the battery cells. A battery cell management system is disposed for each battery cell, and each of a plurality of battery cell management systems may transmit and receive data with the battery management system <NUM> that monitors and controls the battery module. The operation and function of the battery cell management system is similar to those of the battery management system <NUM>.

Here, the switching unit <NUM> is a semiconductor switching element for controlling the current flow for charging or discharging the battery module <NUM>, and, for example, at least one MOSFET can be used.

In addition, the BMS <NUM> can measure or calculate a voltage and current of a gate, source, drain, etc. of the semiconductor switching element in order to monitor a voltage, current, temperature, etc. of the battery module <NUM>, and can also measure the current, voltage, temperature, etc. of the battery module by using a sensor <NUM> provided adjacent to the semiconductor switching element. The BMS <NUM> is an interface that receives values obtained by measuring the various parameters described above, and can include a plurality of terminals and a circuit connected to these terminals to perform processing of input values.

In addition, the BMS <NUM> can control ON/OFF of the switching element <NUM>, for example, a MOSFET, and may be connected to the battery module <NUM> to monitor the state of the battery module <NUM>.

The upper-level controller <NUM> can transmit a control signal for the battery module to the BMS <NUM>. Accordingly, the operation of the BMS <NUM> can also be controlled based on a signal applied from the upper-level controller <NUM>. The battery cell of the present invention can be configured to be included in a battery pack used for an ESS or a vehicle. However, it is not limited to these uses. However, the battery cell is not limited to these uses.

Since the configuration of the battery pack <NUM> and the configuration of the BMS <NUM> are known configurations, a more detailed description will be omitted.

Meanwhile, the apparatus for diagnosing the battery cell according to embodiments of the present invention can be connected to each of a plurality of battery cells connected in series in the battery module <NUM> to determine an abnormality of the battery cell.

<FIG> is a block diagram illustrating a configuration of an apparatus for diagnosing a battery cell according to an embodiment of the present invention. Here, the apparatus for diagnosing the battery cell corresponds to the battery cell management system described above.

Referring to <FIG>, an apparatus <NUM> for diagnosing a battery cell according to an embodiment of the present invention can include a voltage measurement unit <NUM>, a memory <NUM>, an abnormality detection unit <NUM>, and an SOC calculation unit <NUM>.

The voltage measurement unit <NUM> can measure the voltage of each battery cell of the battery module in a state of an open circuit voltage of a battery. In this case, the open circuit voltage of the battery may mean a voltage measured in a state in which the battery cell is not charged or discharged, that is, in a rest state.

In addition, the voltage measurement unit <NUM> can measure the voltage of each battery cell in the state of the open circuit voltage of the battery at predetermined time intervals. For example, the voltage measurement unit <NUM> can measure the voltage of the battery cell every second. However, the present invention is not limited thereto, and the voltage measurement unit <NUM> can measure the voltage at various time intervals set by the user.

The memory <NUM> can store the voltage measured by the voltage measurement unit <NUM> and an SOC calculated by the SOC calculation unit <NUM> at predetermined time intervals. For example, the memory <NUM> can store the voltage measured by the voltage measurement unit <NUM> and the SOC calculated by the SOC calculation unit <NUM> every second.

The abnormality detection unit <NUM> can compare the current measured voltage with the measured voltage before a preset time for each battery cell of the battery, and can determine that an abnormality has occurred in the battery cell of the battery when the difference between the current measured voltage and the measured voltage before the preset time exceeds a reference value.

For example, the measured voltage before the preset time may be a measured voltage <NUM> seconds before the present. In this case, the abnormality detection unit <NUM> can determine a battery cell abnormality of the battery according to the following equation.

The above equation represents a case where the reference value is 10mV. However, the reference value is not limited thereto, and the reference value may be appropriately set depending on a case. For example, the reference value may be set in consideration of an error range of the voltage measurement unit <NUM>. The difference between the current measured voltage and the measured voltage before the preset time is an absolute value, and may include not only a voltage drop amount of the battery cell but also a voltage rise amount of the battery cell.

The abnormality detection unit <NUM> can compare a current SOC calculated by the SOC calculation unit <NUM> and an SOC before a preset time for each battery cell, and determine that an abnormality has occurred in the battery cell when the difference between the current SOC and the SOC before the preset time exceeds a reference value. For example, the reference value may be <NUM>% of the total SOC.

In addition, the abnormality detection unit <NUM> can compare the current measured voltage (or SOC) and the measured voltage (or SOC) before a preset time for each battery cell only when a preset condition is satisfied. In this case, the preset condition may include a condition that a state, in which the current flowing through the battery module is <NUM>, continues for <NUM> seconds or more and the SOC of the battery cell is greater than or equal to a preset numerical value. For example, the preset numerical value of the SOC may include one that the SOC is <NUM>% or more. The reason is that each battery cell model has an OCV characteristic curve and it is intended to prevent erroneous detection by excluding a SOC section where a steep slope appears.

In addition, the abnormality detection unit <NUM> can perform abnormality diagnosis of a battery cell when <NUM> seconds has elapsed from the time point when charging or discharging of the battery is finished and the current flowing through the battery module is <NUM>.

The abnormality detection unit <NUM> can determine that an abnormality has occurred in the battery cell when the state in which the difference between the current measured voltage and the measured voltage before the preset time exceeds the reference value has occurred two or more times in succession. Through this, the abnormality detection unit <NUM> can increase accuracy of abnormality detection of the battery cell of the battery.

The SOC calculation unit <NUM> can calculate the SOC of each battery cell of the battery module based on the voltage measured by the voltage measurement unit <NUM>. The SOC calculation unit <NUM> can calculate the SOC by considering various factors such as current, temperature, pressure, etc. of each battery cell as well as voltage of each battery cell of the battery module.

Here, the SOC calculation method of the battery cell may be classified according to a parameter used as a criterion for determining a residual amount. An Ah method is a method that calculates a used capacity using a relationship between the current and time used and reflects the used capacity in the SOC, and a resistance measurement method is a method of calculating a residual amount based on the relationship between an internal resistance-drop (IR-drop) of the battery and the SOC. In addition, a voltage measurement method is a method of measuring an open circuit voltage (OCV) of a battery terminal and calculating a residual amount based on the relationship between the OCV and SOC measured in advance.

For example, in the case of the apparatus for diagnosing the battery cell according to an embodiment of the present invention, the SOC may be calculated using the voltage measurement method. However, this is only an example and the SOC calculation method is not limited to the methods described above.

In addition, according to the apparatus for diagnosing the battery cell <NUM> of <FIG> according to the embodiment, the abnormality detection unit <NUM> can compare the current measured voltage and SOC with the measured voltage and SOC before a preset time for each battery cell of the battery, and can determine that an abnormality has occurred in the battery cell when the difference between the current measured voltage and SOC and the measured voltage and SOC before the preset time exceeds a reference value.

By using both the measured voltage and the SOC of the battery cell in this way, it is possible to improve the accuracy in detecting an abnormality in cell voltage behavior due to an instantaneous internal short circuit of each battery cell of the battery.

<FIG> and <FIG> illustrate a method of detecting an abnormality in cell voltage behavior due to an instantaneous internal short circuit of a battery cell by the apparatus for diagnosing the battery cell according to the embodiment of the present invention.

In the upper graphs of <FIG> and <FIG>, the horizontal axis represents time (seconds), and the vertical axis represents voltage (V). In addition, the lower tables of <FIG> and <FIG> lists the measured voltage of each battery cell of the battery module and the voltage before a predetermined time, by time. In this case, in the examples of <FIG> and <FIG>, it is assumed that the reference value for detecting an abnormality in cell voltage behavior due to an instantaneous internal short circuit of the battery cell is <NUM> mV.

Referring to <FIG>, for a voltage of <NUM> V measured at <NUM> seconds, the voltage before <NUM> seconds is <NUM> V and the voltage before <NUM> seconds is <NUM> V, and thus the difference is <NUM> mV and <NUM> mV, respectively. Accordingly, the apparatus for diagnosing a battery cell according to an embodiment of the present invention may determine that the abnormality in cell voltage behavior due to the instantaneous internal short circuit of the battery cell has occurred at <NUM> seconds.

In addition, the voltage before <NUM> seconds is <NUM> V with respect to the voltage of <NUM> V measured at <NUM> seconds, and thus the difference is <NUM> mV. Accordingly, the apparatus for diagnosing the battery cell according to the embodiment of the present invention may determine that the abnormality in cell voltage behavior due to the instantaneous internal short circuit of the battery cell has occurred at <NUM> seconds.

Also, in the case of <FIG>, similar to <FIG>, the difference between the voltages measured at <NUM> seconds to <NUM> seconds and the voltage before a predetermined time (e.g., <NUM> second or more) is <NUM> mV or more, it can be determined that the abnormality in cell voltage behavior due to the instantaneous internal short circuit of the battery cell has occurred.

<FIG> is a flowchart illustrating a method for diagnosing a battery cell according to an embodiment of the present invention.

First, when diagnosing a battery cell according to an embodiment of the present invention, the voltage of each battery cell of the battery module can be measured in a state of an open circuit voltage of the battery (S110). In this case, the open circuit voltage of the battery may mean a voltage measured in a state in which the battery cell is not charged or discharged, that is, in a rest state.

In this case, the voltage of each battery cell in the state of the open circuit voltage of the battery can be measured at predetermined time intervals, for example, every second interval. The voltage of each battery cell can be measured.

Next, the measured voltage may be stored at a predetermined time interval (S120). In this case, the voltage measured every second may be stored in the memory. In addition, for each battery cell, a current measured voltage and a measured voltage before a preset time may be compared (S130). In this case, the preset time may be <NUM> seconds.

In addition, before comparing the current measured voltage with the measured voltage before the preset time for each battery cell, measuring a current flowing through the battery module and an SOC of the battery cell can be further included. In the measuring the current flowing through the battery module and the SOC of the battery cell, when the state in which the current flowing through the battery module is <NUM> continues for <NUM> seconds or more and the SOC of the battery cell is greater than or equal to a preset value, comparing the current measured voltage with the measured voltage before the preset time may be performed for each battery cell. In this case, the preset value of SOC may include one that the SOC is <NUM>% or more.

In addition, before the comparing the current measured voltage and the measured voltage before the preset time for each battery cell, the measuring the current flowing through the battery module can be further included. In the measuring the current flowing through the battery module, when <NUM> seconds have elapsed from the time point when charging or discharging of the battery is finished and the current flowing through the battery module is <NUM>, the comparing the current measured voltage and the measured voltage before the preset time for each battery cell can be performed.

As described above, the difference between the current measured voltage and the measured voltage before the preset time is an absolute value and may include not only the voltage drop amount of the battery cell but also the voltage rise amount of the battery cell.

In addition, when the difference between the current measured voltage and the measured voltage before the preset time exceeds the reference value, it may be determined that an abnormality has occurred in the battery cell (S140). In this case, when the case in which the difference between the current measured voltage and the measured voltage before the preset time exceeds the reference value has occurred two or more times in succession, it may be determined that an abnormality has occurred in the battery cell.

<FIG> is a flowchart illustrating a method for diagnosing a battery cell according to another embodiment of the present invention.

First, it is possible to measure the voltage of each battery cell of the battery module in the state of an open circuit voltage of the battery (S210). In addition, the SOC of each battery cell of the battery module can be calculated based on the measured voltage (S220). In this case, the SOC may be calculated by considering various factors such as current, temperature, pressure, etc. of each battery cell as well as the voltage of each battery cell of the battery module.

Next, the measured voltage and the calculated SOC can be stored at predetermined time intervals(S230). In addition, for each battery cell, the current SOC and the SOC before a preset time can be compared (S240). When the difference between the current SOC and the SOC before the preset time exceeds the reference value, it may be determined that an abnormality has occurred in the battery cell (S250).

Meanwhile, although not illustrated in <FIG>, by comparing both the measured voltage and the SOC of each battery cell of the battery module, it is possible to detect an abnormality in cell voltage behavior due to an instantaneous internal short circuit of the battery cell.

<FIG> is a block diagram illustrating a hardware configuration of an apparatus for diagnosing a battery cell according to an embodiment of the present invention.

As illustrated in <FIG>, an apparatus <NUM> for diagnosing a battery cell can include a microcontroller (MCU) <NUM> that controls various processes and configurations, a memory <NUM> in which an operating system program and various programs (e.g., a battery pack abnormality diagnosis program or a battery pack temperature estimation program), etc. are recorded, an input and output interface <NUM> that provides an input interface and an output interface between the battery cell module and/or switching unit (e.g., semiconductor switching element), and a communication interface <NUM> capable of communicating with the outside (e.g., upper-level controller) through a wired or wireless communication network. In this way, the computer program according to the present invention is recorded in the memory <NUM> and processed by the microcontroller <NUM>, and thus, may be implemented as, for example, a module that performs the respective functional blocks illustrated in <FIG>.

In this way, according to the apparatus and method for diagnosing a battery cell according to an embodiment of the present invention, an abnormality in cell voltage behavior due to an instantaneous internal short circuit of the battery cell can be detected early.

In the above description, just because all the constituent elements constituting an embodiment of the present invention are described as being combined into one or operating in combination, the present invention is not necessarily limited to these embodiments. That is, as long as it is within the scope of the claimed invention, all of the constituent elements may be selectively combined and operated in one or more.

In addition, the terms such as "include", "configure" or "have" described above mean that the corresponding the constituent element can be embedded unless otherwise described, and thus it should be interpreted as not excluding other constituent elements, but can further include other constituent elements. All terms used herein including technical or scientific terms may have the same meaning as generally understood by a person of ordinary skill in the art, unless otherwise defined. Terms generally used, such as terms defined in the dictionary, should be interpreted as being consistent with the meaning of the context of the related technology, and are not to be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present invention.

Claim 1:
An apparatus (<NUM>) for diagnosing a battery module comprising battery cells, the apparatus comprising:
a voltage measurement unit (<NUM>) adapted to measure a voltage of each battery cell of the battery module (<NUM>) in a state of an open circuit voltage of a battery;
a state of charge, SOC, calculation unit (<NUM>) adapted to calculate SOC of each battery cell of the battery module based on the measured voltage;
a memory (<NUM>) adapted to store the measured voltage and the calculated SOC at predetermined time intervals; and
an abnormality detection unit (<NUM>) adapted to compare a current measured voltage and the SOC calculated based on the current measured voltage with a voltage measured before a preset time and the SOC calculated based on the voltage measured before the preset time for each battery cell of the battery module and determine that an abnormality has occurred in the battery cell when an absolute value of difference between the current measured voltage and the voltage measured before the preset time exceeds a first reference value and a difference between the SOC calculated from current measured voltage and the SOC calculated from a voltage measured before the preset time exceeds a second reference value.