Battery management device and its operating method

Abstract

A battery management device according to one embodiment includes a first comparator that compares a voltage of a battery cell with a first reference voltage, a switching circuit that sets a path electrically connecting the battery cell to a first path or a second path based on a comparison result by the first comparator, and an impedance calculation unit that calculates an impedance of the battery cell based on a first voltage applied via the first path or a second voltage applied via the second path.

Description

Technical Field

[0001] The present invention claims the benefit of priority based on Korean Patent Application No. 10-2022-0113105 filed on September 6, 2022, and all the contents disclosed in the document of the Korean patent application are incorporated herein by reference in their entirety. The embodiments disclosed in the present application relate to a battery management device and an operating method thereof.

Background Art

[0002] In recent years, research and development on secondary batteries have been actively conducted. A secondary battery is a rechargeable battery, including both conventional Ni / Cd batteries, Ni / MH (nickel / metal hydride) batteries, etc., and recent lithium-ion batteries. Among them, lithium-ion batteries have the advantage of much higher energy density compared to conventional Ni / Cd batteries, Ni / MH batteries, etc. Since lithium-ion batteries can be manufactured in a small and light form, they are widely used as a power source for mobile devices. In recent years, their use range has been extended to the power source of electric vehicles and they have attracted attention as a next-generation energy storage medium.

[0003] Electrochemical impedance spectroscopy (EIS) is a technique that extracts equivalent circuit parameters of a battery based on impedance values ​​measured after applying AC power at different frequencies to the battery, and is used to estimate the battery's lifespan and condition. However, unlike typical battery cells with an operating voltage of approximately 3-4.2V, battery cells with an operating voltage of 2.5V or less require a separate voltage amplifier to amplify the measured voltage, as voltage measurement in the impedance measurement section becomes difficult. Furthermore, for battery cells with an operating voltage of 1V or less, the current flowing through the resistor for impedance measurement drops to one-third, requiring another amplifier with an added parallel resistor to amplify the current. For this reason, conventional EIS measuring devices had to use separate circuits for measuring typical battery cells and low-voltage battery cells, depending on the battery cell's operating voltage. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] One object of the embodiments disclosed herein is to provide a battery management device capable of impedance measurement for both general battery cells and low-voltage battery cells. One object of the embodiments disclosed herein is to provide a battery management device that can reduce measurement errors caused by noise.

[0005] The technical problems of the embodiments disclosed herein are not limited to those mentioned above, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0006] A battery management device according to one embodiment may include: a first comparator that compares the voltage of a battery cell with a first reference voltage; a switching circuit that sets the path through which the battery cell and an impedance calculation unit are electrically connected as a first path or a second path based on the comparison result of the first comparator; and an impedance calculation unit that calculates the impedance of the battery cell based on a first voltage applied through the first path or a second voltage applied through the second path.

[0007] A battery management device according to one embodiment further includes a voltage amplifier located on the second path, which can amplify the voltage of the battery cell to the second voltage when the path is set to the second path.

[0008] In a battery management device according to one embodiment, the switching circuit includes a first switch arranged on the first path and a second switch arranged on the second path. When the voltage of the battery cell is equal to or greater than the first reference voltage, the first switch is made conductive and the second switch is made open, thereby setting the path to the first path. When the voltage of the battery cell is less than the first reference voltage, the first switch is made open and the second switch is made conductive, thereby setting the path to the second path.

[0009] A battery management device according to one embodiment further includes a third switch electrically connected to the battery cell, the third switch can alternately switch on and off according to a specified period, thereby generating an alternating current (AC) to be input to the battery cell.

[0010] A battery management device according to one embodiment may include a current control unit that adjusts the magnitude of the alternating current based on a comparison between the voltage of the battery cell and a second reference voltage.

[0011] In a battery management device according to one embodiment, the current control unit further includes a variable resistor arranged on the path through which the alternating current flows, and can set the variable resistor to a first resistance value when the voltage of the battery cell is equal to or greater than the second reference voltage, and can set the variable resistor to a second resistance value smaller than the first resistance value when the voltage of the battery cell is less than the second reference voltage.

[0012] In a battery management device according to one embodiment, the first comparator can adjust the first reference voltage based on the change in the voltage of the battery cell over a predetermined time interval.

[0013] In a battery management device according to one embodiment, the first comparator can increase the first reference voltage when the voltage of the battery cell increases by a first specified level or more in a predetermined time interval, and can decrease the first reference voltage when the voltage of the battery cell decreases by a second specified level or more in a predetermined time interval.

[0014] An operating method for a battery management device according to one embodiment may include the steps of: comparing the voltage of a battery cell with a first reference voltage; setting a path through which the battery cell and the impedance calculation unit are electrically connected as a first path or a second path based on the result of comparing the voltage of the battery cell with the first reference voltage; and calculating the impedance of the battery cell based on a first voltage applied to the impedance calculation unit via the first path, or a second voltage applied to the impedance calculation unit via the second path.

[0015] An operating method of a battery management device according to one embodiment may include the step of amplifying the voltage of the battery cell to a second voltage via a voltage amplifier located on the second path when the path is set to the second path.

[0016] One embodiment of the battery management device may include the step of alternately turning on and off a third switch electrically connected to the battery cell according to a specified period, thereby generating an alternating current (AC) to be input to the battery cell.

[0017] An operating method for a battery management device according to one embodiment may include the step of adjusting the magnitude of the alternating current based on a comparison between the voltage of the battery cell and a second reference voltage.

[0018] In an operating method for a battery management device according to one embodiment, the step of adjusting the magnitude of the alternating current may include setting a variable resistor placed on the path through which the alternating current flows to a first resistance value when the voltage of the battery cell is equal to or greater than the second reference voltage, and setting the variable resistor to a second resistance value smaller than the first resistance value when the voltage of the battery cell is less than the second reference voltage.

[0019] An operating method for a battery management device according to one embodiment may include the step of adjusting the first reference voltage based on a change in the voltage of the battery cell over a predetermined time interval.

[0020] In an operating method for a battery management device according to one embodiment, the step of adjusting the first reference voltage may include increasing the first reference voltage when the voltage of the battery cell increases by a first specified level or more in a predetermined time interval, and decreasing the first reference voltage when the voltage of the battery cell decreases by a second specified level or more in a predetermined time interval. [Effects of the Invention]

[0021] According to a battery management device according to an embodiment, when the voltage of a battery cell is lower than a first reference voltage (for example, 2.5 V), impedance can be calculated using a voltage applied through a path including a voltage amplifier by switching. According to a battery management device according to an embodiment, when the voltage of a battery cell is lower than a second reference voltage (for example, 1 V), the magnitude of the alternating current flowing through the battery cell can be increased. Therefore, it is not necessary to separately use a measuring device according to the operating voltage of the battery cell, and impedance measurement can be easily performed for both general battery cells and low-voltage battery cells.

[0022] <000,0079>Also, during impedance measurement, when the operating voltage of the battery cell is close to the reference voltage, the operations for general battery cells and low-voltage battery cells may be repeated due to noise, resulting in measurement errors. However, according to an embodiment, by adjusting the comparison reference voltage according to whether the voltage of the battery cell instantaneously rises or falls, measurement errors due to noise can be reduced. In addition, according to the present application, various effects that can be directly or indirectly grasped can be provided.

[0023] To more clearly explain the embodiments disclosed in the present application or the technical solutions of the prior art, the drawings necessary for the description of the embodiments are briefly introduced below. It should be understood that the following drawings are only for explaining the embodiments of this specification and are not for limiting purposes. Also, for the sake of clarity of the description, the representation of some components in the drawings may be exaggerated or omitted.

Brief Description of the Drawings

[0024] [Figure 1a] It is a diagram showing the structure of a device for measuring EIS for a battery cell according to an embodiment. [Figure 1b] It is a diagram showing the structure of a device for measuring EIS for a battery cell according to an embodiment. [Figure 2] It is a diagram showing the structure of a battery management device according to an embodiment. [Figure 3a] A diagram showing the connection relationship between components when the voltage of a battery cell is within a first voltage range according to an embodiment. [Figure 3b] A diagram showing the connection relationship between components when the voltage of a battery cell is within a second voltage range according to an embodiment. [Figure 3c] A diagram showing the connection relationship between components when the voltage of a battery cell is within a third voltage range according to an embodiment. [Figure 4] A flowchart showing an operation method of a battery management device according to an embodiment.

Mode for Carrying Out the Invention

[0025] Hereinafter, the embodiments disclosed in the present application will be described in detail with reference to exemplary drawings. Note that when assigning reference numerals to the components of each drawing, the same components are assigned the same numerals as much as possible when displayed on other drawings. Further, when explaining the embodiments disclosed in the present application, if a specific explanation of a related known configuration or function is determined to impede the understanding of the embodiments disclosed in the present application, the detailed explanation thereof will be omitted.

[0026] The terms used in the present application are generally widely used terms selected as much as possible while considering their functions. However, this may vary depending on the intention or convention of those skilled in the art or the emergence of new technologies. Also, in certain cases, there are terms arbitrarily selected by the applicant, and in such cases, the meaning thereof is described in the description part of the specification. Therefore, it is clarified that the terms used in the present application should not be construed merely as the names of the terms, but should be interpreted based on the substantial meaning of the terms and the overall content of the present application.

[0027] Furthermore, the terms used in this application are used solely to describe specific embodiments and are not intended to limit the scope of other embodiments. Singular expressions may include plural expressions unless the context clearly indicates otherwise. Also, in this application, expressions such as "first" and "second" are used to distinguish components from one another and do not imply any rank or order among the components.

[0028] A preferred embodiment of the battery management device and its operating method will be described below with reference to the drawings. Figure 1a shows the structure of an apparatus for measuring EIS for a battery cell according to one embodiment.

[0029] For a typical battery cell (B) operating within a common voltage range (e.g., approximately 3-4.2V), the AC impedance can be measured via the EIS measurement unit without the need for special additional circuitry. The EIS measurement unit can measure and display the impedance response output to the battery cell (B) at different frequencies after an AC signal is applied.

[0030] For example, the EIS measurement unit can consist of an AC signal generation unit that generates AC signals for each frequency and inputs them to the battery cell, and an impedance calculation unit that receives the battery's output signal (e.g., voltage value) in response to the input AC signal and calculates the impedance for each frequency. Parameters of the battery cell (B) (e.g., internal resistance) can be obtained from the impedance response obtained by frequency sweep, thereby providing information about the battery cell's condition, such as its degree of degradation, remaining lifespan, and whether or not there are any abnormalities.

[0031] Figure 1b is a schematic diagram showing the structure of an apparatus for measuring EIS for a battery cell according to one embodiment. Unlike typical battery cells, low-voltage battery cells that operate in a voltage range lower than the first reference voltage (e.g., 2.5V) result in a smaller voltage being applied to the EIS measurement unit.

[0032] Furthermore, in the case of low-voltage battery cells that operate in a voltage range lower than the second reference voltage (e.g., 1V), not only is the magnitude of the voltage applied to the EIS measurement unit reduced, but the magnitude of the current flowing through the resistor in the EIS measurement unit also reduced proportionally to the magnitude of the voltage. For example, compared to a battery cell with an operating voltage of 3V in the same circuit, the current flowing through a low-voltage battery cell with an operating voltage of 1V is reduced to 1 / 3 (Ohm's law, V=I×R).

[0033] Therefore, generally, an EIS measurement circuit for a low-voltage battery cell includes either a separate voltage amplifier to amplify the low voltage, as shown in the circuit structure of Figure 1b, or a separate current amplifier to amplify the AC current flowing through the battery cell. For example, the voltage amplifier may include an inverting amplifier. The current amplifier may include one or more parallel resistors to increase the current by the ratio of the decreasing voltage.

[0034] Figure 2 is a schematic diagram showing the structure of a battery management device according to one embodiment. Referring to Figure 2, a battery management device according to one embodiment may include a first comparator 100, a switching circuit 200, a voltage amplifier 300, an impedance calculation unit 400, a third switch 410, and / or a current control unit 500. According to one embodiment, the battery management device may omit at least one of the components shown in Figure 2, or one or more other components may be added.

[0035] The first comparator 100 is configured to compare the voltage of the battery cell (B) with the first reference voltage and transmit the result to the switching circuit 200. According to one embodiment, the first reference voltage can be set in the range of 1 to 3V. For example, the first reference voltage can be set to 2.5V.

[0036] Based on the comparison results from the first comparator 100, the switching circuit 200 can set the path through which the battery cell (B) and the impedance calculation unit 400 are electrically connected to either the first path 211 or the second path 221.

[0037] According to one embodiment, the switching circuit 200 can be configured to electrically connect the battery cell (B) and the impedance calculation unit 400 via a first path 211 that does not include a voltage amplifier 300 when the voltage of the battery cell (B) is equal to or greater than the first reference voltage. According to one embodiment, the switching circuit 200 can be configured to electrically connect the battery cell (B) and the impedance calculation unit 400 via a second path 221 that includes a voltage amplifier 300 when the voltage of the battery cell (B) is less than the first reference voltage.

[0038] According to one embodiment, the switching circuit 200 may include a first switch 210 and / or a second switch 220. According to one embodiment, the switching circuit 200 may be configured to electrically connect the battery cell (B) and the impedance calculation unit 400 via the first path 211 by opening the first switch 210 located on the first path 211 and opening the second switch 220 located on the second path 221 which includes the voltage amplifier 300 when the voltage of the battery cell (B) is equal to or greater than the first reference voltage. According to one embodiment, the switching circuit 200 may be configured to electrically connect the battery cell (B) and the impedance calculation unit 400 via the second path 221 by opening the first switch 210 located on the first path 211 and opening the second switch 220 located on the second path 221 which includes the voltage amplifier 300 when the voltage of the battery cell (B) is less than the first reference voltage.

[0039] The voltage amplifier 300 can amplify the voltage of the battery cell (B) applied to the impedance calculation unit 400 via the second path 221. For example, the voltage amplifier 300 can be configured as an inverting amplifier.

[0040] The impedance calculation unit 400 can calculate the impedance of the battery cell (B) based on the voltage applied through a designated path (for example, the first path 211 or the second path 221). According to one embodiment, the impedance calculation unit 400 can calculate the impedance of the battery cell (B) based on a first voltage applied through the first path 211 or a second voltage applied through the second path 221. According to one embodiment, the impedance calculation unit 400 can calculate the impedance of the battery cell (B) based on the change in the first voltage or the change in the second voltage. According to another embodiment, the impedance calculation unit 400 can calculate the impedance of the battery cell (B) based on the derivative of the first voltage or the derivative of the second voltage.

[0041] Thus, according to the battery management device of this embodiment, the voltage of a battery cell is compared with a first reference voltage. If the battery cell has an operating voltage equal to or greater than the first reference voltage, the impedance can be measured without voltage amplification. If the battery cell has an operating voltage less than the first reference voltage, the impedance can be measured after the voltage is amplified by circuit switching.

[0042] According to one embodiment, the impedance calculation unit 400 may be an EIS (Electrochemical Impedance Spectroscopy) measurement circuit or a device including the same that calculates the AC impedance to an AC voltage signal applied to a battery cell. According to one embodiment, the battery management device may further include an AC signal generation unit that generates frequency-specific AC signals and inputs them to the battery cell. According to one embodiment, the battery management device can generate an alternating current (AC) flowing to the battery cell (B) via a third path 411 including the battery cell (B) and the third switch 410 by alternately turning a third switch 410, which is electrically connected to the battery cell (B), on and off according to a specified period. For example, the impedance calculation unit 400 can control the third switch 410 so that it alternately turns on and off according to a specified period.

[0043] The current control unit 500 can adjust the magnitude of the alternating current flowing through the battery cell (B) via the third path 411 based on a comparison of the voltage of the battery cell (B) with the second reference voltage. Here, the second reference voltage can be set lower than the first reference voltage. For example, the second reference voltage can be set to 1V.

[0044] According to one embodiment, the current control unit 500 may include a second comparator 510 and / or a variable resistor 520. According to one embodiment, the current control unit 500 can compare the voltage of the battery cell (B) with the second reference voltage via the second comparator 510 and set the resistance value of the variable resistor 520 based on the comparison result.

[0045] The current control unit 500 can adjust the magnitude of the alternating current flowing through the third path 411 by adjusting the resistance value of the variable resistor 520 based on the comparison result via the second comparator 510. According to one embodiment, the current control unit 500 can set the variable resistor 520 to a first resistance value when the voltage of the battery cell (B) is equal to or greater than the second reference voltage. The current control unit 500 can set the variable resistor 520 to a second resistance value when the voltage of the battery cell (B) is less than the second reference voltage. Here, the second resistance value may be smaller than the first resistance value.

[0046] According to one embodiment, the variable resistor 520 may include a fourth switch 521, a first resistor 523, and a second resistor 525. According to one embodiment, the first resistor 523 and the second resistor 525 may be connected in parallel with each other on the third path 411 between the battery cell (B) and the third switch 410. The fourth switch 521 may be connected in series with the second resistor 525.

[0047] According to one embodiment, the current control unit 500 can open the fourth switch 521 when the voltage of the battery cell (B) is equal to or greater than the second reference voltage. In this case, the alternating current can flow only through the first resistor 523.

[0048] According to one embodiment, the current control unit 500 can conduct the fourth switch 521 when the voltage of the battery cell (B) is less than the second reference voltage. In this case, the alternating current can flow through the first resistor 523 and the second resistor 525 which are connected in parallel. In this way, the current control unit 500 can increase the magnitude of the alternating current flowing through the battery cell (B) by connecting an additional parallel resistor when the voltage of the battery cell (B) is less than the second reference voltage.

[0049] The following describes the connections between the components of the battery management device when the voltage of the battery cell (B) is within the first voltage range, the second voltage range, or the third voltage range, with reference to Figures 3a, 3b, and 3c. Here, the first voltage range may mean the range where the voltage is equal to or greater than the first reference voltage. The second voltage range may mean the range where the voltage is equal to or greater than the second reference voltage, which is lower than the first reference voltage, and less than the first reference voltage. The third voltage range may mean the range where the voltage is less than the second reference voltage.

[0050] Figure 3a is a diagram showing the connection relationships between components when the voltage of the battery cell is within a first voltage range, according to one embodiment. Referring to Figure 3a, the battery management device can electrically connect the battery cell (B) and the impedance calculation unit 400 via a first path 211 that does not include the voltage amplifier 300 by opening the first switch 210 and opening the second switch 220 when the voltage of the battery cell (B) is within the first voltage range. Alternatively, the battery management device can open the fourth switch 521 when the voltage of the battery cell (B) is above the second reference voltage, allowing the alternating current to flow through the first resistor 523. In this case, the impedance calculation unit 400 can calculate the impedance of the battery cell (B) based on the first voltage applied via the first path 211.

[0051] Figure 3b is a diagram showing the connection relationships between components when the voltage of the battery cell is within a second voltage range, according to one embodiment. Referring to Figure 3b, the battery management device can open the first switch 210 and open the second switch 220 when the voltage of the battery cell (B) is within the second voltage range, thereby electrically connecting the battery cell (B) and the impedance calculation unit 400 via the second path 221, which includes the voltage amplifier 300. Alternatively, the battery management device can open the fourth switch 521 when the voltage of the battery cell (B) is above the second reference voltage, allowing the alternating current to flow through the first resistor 523. In this case, the impedance calculation unit 400 can calculate the impedance of the battery cell (B) based on the second voltage applied via the second path 221. The second voltage may be a voltage amplified by the voltage amplifier 300.

[0052] Figure 3c is a diagram showing the connection relationships between components when the voltage of the battery cell is within a third voltage range, according to one embodiment. Referring to Figure 3c, the battery management device can open the first switch 210 and open the second switch 220 when the voltage of the battery cell (B) is within the third voltage range, thereby electrically connecting the battery cell (B) and the impedance calculation unit 400 via the second path 221, which includes the voltage amplifier 300. Alternatively, the battery management device can open the fourth switch 521 when the voltage of the battery cell (B) is below the second reference voltage, allowing an AC current to flow through the first resistor 523 and the second resistor 525, which are connected in parallel. In this case, the impedance calculation unit 400 can calculate the impedance of the battery cell (B) based on the second voltage applied via the second path 221. The second voltage may be a voltage amplified by the voltage amplifier 300.

[0053] On the other hand, in impedance measurements using a general comparator, some problems can occur when the voltage of the battery cell does not differ significantly from the reference voltage. For example, when measuring the impedance of battery cell (B) using the battery management device shown in Figure 2, assuming that the reference voltage of the first comparator 100 is 2.5V and the voltage of battery cell (B) is 2.5V, if the cell voltage momentarily rises to 2.51V due to noise, the impedance will be calculated via the first path 211 which does not include the voltage amplifier 300, and if the cell voltage momentarily drops to 2.49V, the impedance will be calculated via the second path 221 which includes the voltage amplifier 300. In this way, when the voltage of the battery cell does not differ significantly from the reference voltage, repeated circuit switching due to noise can lead to large measurement errors.

[0054] According to one embodiment of a battery management device for solving the above problems, the reference voltage of the first comparator 100 can be adjusted depending on whether the voltage of the battery cell (B) is increasing or decreasing, thereby enabling the impedance calculation unit 400 to operate more stably and reducing errors.

[0055] According to one embodiment, the first comparator 100 can adjust the first reference voltage based on the change in the voltage of the battery cell (B) over a predetermined time interval. For example, the first comparator 100 can increase the first reference voltage (e.g., 2.5V) if the voltage of the battery cell (B) increases by a first specified level or more over a predetermined time interval, and decrease the first reference voltage (e.g., 2.5V) if the voltage of the battery cell (B) decreases by a second specified level or more over a predetermined time interval.

[0056] In this case, even if the battery cell voltage momentarily rises to 2.51V or momentarily drops to 2.49V, the impedance can be calculated based on the voltage applied through the first path 211, which does not include the voltage amplifier 300. According to one embodiment, the impedance calculation unit 400 can be configured to have hysteresis characteristics.

[0057] Figure 4 is a flowchart showing the operation method of a battery management device according to one embodiment. The operation method of the embodiment may be performed by the battery management device according to the above embodiment, but is not limited thereto, and may be performed by a battery management device having other forms or structures.

[0058] Referring to Figure 4, in step (S100), the voltage of the battery cell is compared with the reference voltage. According to one embodiment, the reference voltage can be set in the range of 1 to 3V. For example, assuming the reference voltage is 2.5V, it is possible to distinguish between a typical battery cell with an operating voltage of 3V or higher, or a low-voltage battery cell that operates at a voltage lower than that.

[0059] In step (S100), the battery management device can compare the voltage of the battery cell (B) with a first reference voltage and / or a second reference voltage. According to one embodiment, the first reference voltage can be set in the range of 1 to 3V. For example, the first reference voltage can be set to 2.5V. The second reference voltage can be set lower than the first reference voltage. For example, the second reference voltage can be set to 1V.

[0060] According to one embodiment, the battery management device can adjust a first reference voltage based on a change in the voltage of a battery cell (B) over a predetermined time interval. For example, the battery management device can increase the first reference voltage if the voltage of the battery cell (B) increases by a first specified level or more over a predetermined time interval. The battery management device can decrease the first reference voltage if the voltage of the battery cell (B) decreases by a second specified level or more over a predetermined time interval.

[0061] In step (S200), the battery management device can set the electrical connection paths within the battery management device based on the comparison results from step (S100).

[0062] According to one embodiment, the battery management device can set the path through which the battery cell (B) and the impedance calculation unit 400 are electrically connected to either the first path 211 or the second path 221 based on the comparison result of step (S100). According to one embodiment, if the voltage of the battery cell (B) is equal to or greater than the first reference voltage, the battery management device can electrically connect the battery cell (B) and the impedance calculation unit 400 via the first path 211, which does not include the voltage amplifier 300. According to one embodiment, if the voltage of the battery cell (B) is less than the first reference voltage, the battery management device can electrically connect the battery cell (B) and the impedance calculation unit 400 via the second path 221, which includes the voltage amplifier 300.

[0063] According to one embodiment, when the voltage of the battery cell (B) is equal to or greater than the first reference voltage, the battery management device can open the first switch 210 located on the first path 211 and open the second switch 220 located on the second path 221 which includes the voltage amplifier 300, thereby electrically connecting the battery cell (B) and the impedance calculation unit 400 via the first path 211. According to one embodiment, when the voltage of the battery cell (B) is less than the first reference voltage, the battery management device can open the first switch 210 located on the first path 211 and open the second switch 220 located on the second path 221 which includes the voltage amplifier 300, thereby electrically connecting the battery cell (B) and the impedance calculation unit 400 via the second path 221.

[0064] According to one embodiment, the battery management device can adjust the magnitude of the alternating current flowing to the battery cell (B) via the third path 411 based on the comparison result of step (S100).

[0065] According to one embodiment, the battery management device can adjust the magnitude of the alternating current flowing through the third path 411 by adjusting the resistance value of the variable resistor 520 when the voltage of the battery cell (B) is equal to or greater than the second reference voltage. According to one embodiment, the battery management device can set the variable resistor 520 to a first resistance value when the voltage of the battery cell (B) is equal to or greater than the second reference voltage. The battery management device can set the variable resistor 520 to a second resistance value when the voltage of the battery cell (B) is less than the second reference voltage. Here, the second resistance value may be smaller than the first resistance value.

[0066] According to one embodiment, the variable resistor 520 may include a fourth switch 521, a first resistor 523, and a second resistor 525. According to one embodiment, the first resistor 523 and the second resistor 525 may be connected in parallel with each other on the third path 411 between the battery cell (B) and the third switch 410. The fourth switch 521 may be connected in series with the second resistor 525.

[0067] According to one embodiment, the battery management device can open the fourth switch 521 when the voltage of the battery cell (B) is equal to or greater than the second reference voltage. In this case, the alternating current can flow only through the first resistor 523.

[0068] According to one embodiment, the battery management device can conduct the fourth switch 521 when the voltage of the battery cell (B) is less than the second reference voltage. In this case, the alternating current can flow through the first resistor 523 and the second resistor 525 which are connected in parallel.

[0069] In step (S300), the battery management device can calculate the impedance of the battery cell (B) based on the voltage applied to the impedance calculation unit 400. According to one embodiment, the battery management device can calculate the impedance of the battery cell (B) based on a first voltage applied to the impedance calculation unit 400 via a first path 211 including a first switch 210, or a second voltage applied to the impedance calculation unit 400 via a second path 221 including a second switch 220 and a voltage amplifier 300. According to one embodiment, the battery management device can calculate the impedance of the battery cell (B) based on the change in the first voltage or the change in the second voltage. According to another embodiment, the battery management device can calculate the impedance of the battery cell (B) based on the derivative of the first voltage or the derivative of the second voltage.

[0070] The operation method of the battery management device according to the above embodiment can be implemented in an application or in the form of program instructions that can be executed via various computer components and recorded on a computer-readable recording medium. The computer-readable recording medium may include program instructions, data files, data structures, etc., individually or in combination.

[0071] According to the battery management device described above, there is no need to use different measuring devices depending on the operating voltage of the battery cells. Impedance can be easily measured for both general-purpose and low-voltage battery cells, and status information such as the degree of degradation, remaining lifespan, and presence or absence of abnormalities of the battery cells can be obtained by utilizing Nyquist plots drawn according to the AC impedance response at different frequencies.

[0072] Although the embodiments described above have shown that all components constituting the embodiments are either combined into one or operate in combination, the embodiments are not necessarily limited to such embodiments, and all components may selectively combine into one or more combinations to operate within the scope of the purpose. Furthermore, unless otherwise stated, terms such as "includes," "constitutes," or "has" used above mean that the component in question may be inherent, and therefore should be interpreted as including other components rather than excluding them.

[0073] The above description is merely illustrative of the technical concept disclosed herein, and any person with ordinary skill in the art to which the embodiments disclosed herein belong can make various modifications and variations without departing from the essential characteristics of the embodiments disclosed herein.

[0074] Therefore, the embodiments disclosed in this application are for illustrative purposes only, not to limit, the technical concept disclosed in this application, and the scope of the technical concept disclosed in this application is not limited by such embodiments. The scope of protection of the technical concept disclosed in this application shall be interpreted according to the claims described below, and all technical concepts within an equivalent scope shall be interpreted as being included in the scope of rights of this application.

Claims

1. A first comparator compares the voltage of the battery cell with a first reference voltage, A switching circuit sets the path through which the battery cell and the impedance calculation unit are electrically connected to the first path or the second path based on the comparison result from the first comparator, A battery management device including an impedance calculation unit that calculates the impedance of the battery cell based on a first voltage applied via the first path or a second voltage applied via the second path.

2. The second path further includes a voltage amplifier located on the second path, The battery management device according to claim 1, wherein the voltage amplifier amplifies the voltage of the battery cell to the second voltage when the path is set to the second path.

3. The aforementioned switching circuit is This includes a first switch located on the first path and a second switch located on the second path, If the voltage of the battery cell is equal to or greater than the first reference voltage, the first switch is opened and the second switch is opened, thereby setting the path to the first path. The battery management device according to claim 1, wherein if the voltage of the battery cell is less than the first reference voltage, the first switch is opened and the second switch is opened to set the path to the second path.

4. The system further includes a third switch electrically connected to the aforementioned battery cell, The battery management device according to claim 1, wherein the third switch alternately turns on and off according to a specified period to generate an alternating current that is input to the battery cell.

5. The battery management device according to claim 4, further comprising a current control unit that adjusts the magnitude of the alternating current based on a comparison of the voltage of the battery cell with a second reference voltage.

6. The current control unit further includes a variable resistor placed on the path through which the alternating current flows, If the voltage of the battery cell is equal to or greater than the second reference voltage, the variable resistor is set to the first resistance value. The battery management device according to claim 5, wherein if the voltage of the battery cell is less than the second reference voltage, the variable resistor is set to a second resistance value smaller than the first resistance value.

7. The battery management device according to claim 1, wherein the first comparator adjusts the first reference voltage based on the change in the voltage of the battery cell over a predetermined time interval.

8. The first comparator is, The first reference voltage is increased when the voltage of the battery cell increases to a first specified level or more within a predetermined time interval. The battery management device according to claim 7, wherein the first reference voltage is reduced when the voltage of the battery cell decreases by a second specified level or more in a predetermined time interval.

9. The steps include comparing the voltage of the battery cell with the first reference voltage, The steps include: setting the path through which the battery cell and the impedance calculation unit are electrically connected to a first path or a second path based on the result of comparing the voltage of the battery cell with the first reference voltage; A method for operating a battery management device, comprising the step of calculating the impedance of the battery cell based on a first voltage applied to the impedance calculation unit via the first path, or a second voltage applied to the impedance calculation unit via the second path.

10. The method for operating a battery management device according to claim 9, further comprising the step of amplifying the voltage of the battery cell to the second voltage via a voltage amplifier located on the second path when the aforementioned path is set to the second path.

11. The method for operating a battery management device according to claim 9, further comprising the step of alternately turning on and off a third switch electrically connected to the battery cell according to a specified period to generate an alternating current (AC) input to the battery cell.

12. The method for operating a battery management device according to claim 11, further comprising the step of adjusting the magnitude of the alternating current based on the result of comparing the voltage of the battery cell with a second reference voltage.

13. The step of adjusting the magnitude of the alternating current is, If the voltage of the battery cell is equal to or greater than the second reference voltage, the step of setting the variable resistor placed on the path through which the alternating current flows to a first resistance value, A method for operating a battery management device according to claim 12, comprising the step of setting the variable resistor to a second resistance value smaller than the first resistance value when the voltage of the battery cell is less than the second reference voltage.

14. The method for operating a battery management device according to claim 9, further comprising the step of adjusting the first reference voltage based on a change in the voltage of the battery cell over a predetermined time interval.

15. The step of adjusting the first reference voltage is: The steps include increasing the first reference voltage when the voltage of the battery cell increases to a first specified level or more within a predetermined time interval, A method for operating a battery management device according to claim 14, comprising the step of reducing the first reference voltage when the voltage of the battery cell decreases by a second specified level or more in a predetermined time interval.

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