Battery management device and method of operation thereof

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 September 6, 2022, and all contents disclosed in the documents of this Korean patent application are incorporated herein by reference. SUMMARY OF THE INVENTION The disclosed embodiments relate to a battery management device and method of operation. [Background technology]

[0002] In recent years, research and development into secondary batteries has been actively conducted. Secondary batteries are batteries that can be charged and discharged, and include both conventional Ni / Cd batteries, Ni / MH (nickel / metal hydride) batteries, and more recent lithium-ion batteries. Lithium-ion batteries, in particular, have the advantage of having a much higher energy density than conventional Ni / Cd batteries, Ni / MH batteries, and other batteries. Lithium-ion batteries can be manufactured to be small and lightweight, so they are widely used as power sources for mobile devices. In recent years, their range of use has expanded to include power sources for electric vehicles, and they are attracting attention as a next-generation energy storage medium.

[0003] Electrochemical Impedance Spectroscopy (EIS) is a technique for extracting equivalent circuit parameters of a battery based on the impedance values ​​measured after applying AC power at various frequencies to the battery. It is used to estimate the battery's lifespan and condition. However, unlike typical battery cells with an operating voltage of approximately 3 to 4.2 V, battery cells with an operating voltage of 2.5 V or less are difficult to measure in the impedance measurement section, requiring a separate voltage amplifier to amplify the measured voltage. Furthermore, for battery cells with an operating voltage of 1 V or less, the current flowing through the impedance measurement resistor section drops to one-third, requiring a separate amplifier with a parallel resistor to amplify the current. For this reason, conventional EIS measurement devices require separate circuits for measuring typical battery cells and low-voltage battery cells, depending on the operating voltage of the battery cells. Summary of the Invention [Problem to be solved by the invention]

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

[0005] The technical problems of the embodiments disclosed in the present application are not limited to the technical problems mentioned above, and other technical problems not mentioned 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 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.

[0007] In one embodiment, the battery management device further includes a voltage amplifier arranged on the second path, and the voltage amplifier can amplify the voltage of the battery cell to the second voltage when the path is set to the second path.

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

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

[0010] The battery management device according to an embodiment may include a current control unit that adjusts the magnitude of the AC current based on a result of comparing the voltage of the battery cell with a second reference voltage.

[0011] In one embodiment of the battery management device, the current control unit further includes a variable resistor arranged on a path through which the AC 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 one embodiment of the battery management device, the first comparator may adjust the first reference voltage based on a change in the voltage of the battery cell during a predetermined time period.

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

[0014] An operating method of a battery management device according to one embodiment may include the steps of: comparing a voltage of a battery cell with a first reference voltage; setting a path electrically connecting the battery cell to an impedance calculation unit as a first path or a second path based on a result of comparing the voltage of the battery cell with the first reference voltage; and calculating the impedance of the battery cell based on the first voltage applied to the impedance calculation unit via the first path or the 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, when the path is set to the second path, amplifying the voltage of the battery cell to the second voltage via a voltage amplifier arranged on the second path.

[0016] An operating method of a battery management device according to an embodiment may include 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] According to an embodiment, a method for operating a battery management device may include adjusting the magnitude of the AC current based on a result of comparing the voltage of the battery cell with a second reference voltage.

[0018] In one embodiment of a method for operating a battery management device, the step of adjusting the magnitude of the AC current can include the steps of: setting a variable resistor arranged on a path through which the AC 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] According to an embodiment, a method for operating a battery management device may include adjusting the first reference voltage based on a change in the voltage of the battery cell during a predetermined time period.

[0020] In one embodiment of the method for operating a battery management device, adjusting the first reference voltage may include increasing the first reference voltage when the voltage of the battery cell increases by more than a first designated level in a predetermined time period, and decreasing the first reference voltage when the voltage of the battery cell decreases by more than a second designated level in a predetermined time period. [Effects of the Invention]

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

[0022] Furthermore, when measuring impedance, if the operating voltage of a battery cell is close to the reference voltage, noise may cause the battery cell to alternate between operating as a normal battery cell and operating as a low-voltage battery cell, resulting in measurement errors. However, according to one embodiment, the comparison reference voltage is adjusted depending on whether the battery cell voltage momentarily rises or falls, thereby reducing measurement errors caused by noise. In addition, the present invention can provide various other effects that can be directly or indirectly grasped.

[0023] In order to more clearly describe the embodiments disclosed in the present application or the technical solutions of the prior art, the drawings necessary for describing the embodiments are briefly introduced below. It should be understood that the following drawings are only for describing the embodiments of the present specification and are not intended to limit the scope of the invention. In addition, for the sake of clarity, the representation of some components in the drawings may be exaggerated or omitted. [Brief explanation of the drawings]

[0024] [Figure 1a] FIG. 1 illustrates the structure of an apparatus for measuring EIS on a battery cell, according to one embodiment. [Figure 1b] FIG. 1 illustrates the structure of an apparatus for measuring EIS on a battery cell, according to one embodiment. [Figure 2] 1 is a diagram illustrating a structure of a battery management device according to an embodiment. [Figure 3a] 4 is a diagram illustrating a connection relationship between components when the voltage of a battery cell is within a first voltage range, according to one embodiment. [Figure 3b] 10 is a diagram illustrating a connection relationship between components when the voltage of a battery cell is within a second voltage range, according to one embodiment. [Figure 3c] 10 is a diagram illustrating a connection relationship between components when the voltage of a battery cell is within a third voltage range, according to one embodiment. [Figure 4] 1 is a flowchart illustrating an operation method of a battery management device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. It should be noted that when assigning reference numerals to components in each drawing, the same numerals are assigned to the same components when they appear in other drawings as much as possible. Furthermore, when describing the embodiments disclosed herein, if a detailed description of related known structures or functions is deemed to hinder understanding of the embodiments disclosed herein, such detailed description will be omitted.

[0026] The terms used in this application have been selected as widely used and general as possible while taking into consideration their functions, but these may vary depending on the intentions or practices of engineers in the relevant field or the emergence of new technologies. In addition, in certain cases, the applicant has arbitrarily selected terms, and in such cases, the meanings thereof will be described in the explanation section of the specification. Therefore, it is made clear that the terms used in this application should be interpreted based on the substantive meanings of the terms and the overall content of this application, rather than simply on the names of the terms.

[0027] Furthermore, the terms used in this application are merely used to describe particular embodiments and are not intended to limit the scope of other embodiments. A singular expression may include a plural expression unless the context clearly dictates otherwise. Furthermore, in this application, expressions such as "first" and "second" are used to distinguish components from one another and do not imply a ranking or order between the components.

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a battery management device and its operating method will now be described with reference to the drawings. FIG. 1a illustrates the structure of an apparatus for measuring EIS on a battery cell, according to one embodiment.

[0029] For a typical battery cell (B) operating in a typical voltage range (e.g., approximately 3 to 4.2 V), the AC impedance can be measured via the EIS measurement unit without using any special additional circuitry. The EIS measurement unit can measure and display the impedance response output by frequency after applying an AC signal to the battery cell (B).

[0030] For example, the EIS measurement unit can be composed 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 (e.g., internal resistance, etc.) of the battery cell (B) can be obtained from the impedance response due to frequency sweep, and thereby status information such as the degree of deterioration of the battery cell, remaining life, and whether or not there is an abnormality can be known.

[0031] FIG. 1b is a schematic diagram illustrating the structure of an apparatus for measuring EIS on a battery cell, according to one embodiment. Unlike a general battery cell, in the case of a low-voltage battery cell that operates in a voltage range lower than the first reference voltage (for example, 2.5 V), the magnitude of the voltage applied to the EIS measurement unit is small.

[0032] Furthermore, for low-voltage battery cells operating in a voltage range lower than the second reference voltage (e.g., 1 V), not only is the voltage applied to the EIS measurement unit reduced, but the current flowing through the resistance of the EIS measurement unit also decreases in proportion to the voltage. For example, compared to a battery cell operating at 3 V in the same circuit, a low-voltage battery cell operating at 1 V will draw one-third the current (Ohm's Law, V = I × R).

[0033] Therefore, EIS measurement circuits for low-voltage battery cells typically include a separate voltage amplifier to amplify the low voltage, as in the circuit configuration of Figure 1b, or a separate current amplifier to amplify the AC current flowing through the battery cell. For example, the voltage amplifier can include an inverting amplifier. The current amplifier can include one or more parallel resistors to increase the current in proportion to the decreasing voltage.

[0034] FIG. 2 is a schematic diagram showing the structure of a battery management device according to one embodiment. 2, the battery management device according to an 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 an embodiment, at least one of the components of FIG. 2 may be omitted from the battery management device, 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 a first reference voltage and transmit the result to the switching circuit 200. According to one embodiment, the first reference voltage may be set in the range of 1 to 3V. For example, the first reference voltage may be set to 2.5V.

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

[0037] According to an embodiment, the switching circuit 200 may 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 an embodiment, the switching circuit 200 may 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 an embodiment, the switching circuit 200 may include a first switch 210 and / or a second switch 220. According to an embodiment, the switching circuit 200 may be configured to turn on the first switch 210 disposed on the first path 211 and turn on the second switch 220 disposed on the second path 221 including the voltage amplifier 300, when the voltage of the battery cell (B) is equal to or greater than the first reference voltage, thereby electrically connecting the battery cell (B) and the impedance calculation unit 400 via the first path 211. According to an embodiment, the switching circuit 200 may be configured to turn on the first switch 210 disposed on the first path 211 and turn on the second switch 220 disposed on the second path 221 including the voltage amplifier 300, when the voltage of the battery cell (B) is less than the first reference voltage, thereby electrically connecting the battery cell (B) and the impedance calculation unit 400 via the second path 221.

[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 via a specified path (e.g., 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 the first voltage applied via the first path 211 or the second voltage applied via 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 amount of change in the first voltage or the amount of 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 differential value of the first voltage or the differential value of the second voltage.

[0041] In this way, according to the battery management device of the embodiment, the voltage of a battery cell is compared with a first reference voltage, and 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, and if the battery cell has an operating voltage less than the first reference voltage, the impedance can be measured after amplifying the voltage by circuit switching.

[0042] According to one embodiment, the impedance calculation unit 400 may be an electrochemical impedance spectroscopy (EIS) measurement circuit that calculates AC impedance for an AC voltage signal applied to a battery cell or a device including the same. According to one embodiment, the battery management device may further include an AC signal generation unit that generates AC signals according to frequencies and inputs the AC signals to the battery cell. According to one embodiment, the battery management device may alternately turn on and off a third switch 410 electrically connected to the battery cell (B) according to a specified period, thereby generating an alternating current (AC) that flows to the battery cell (B) via a third path 411 including the battery cell (B) and the third switch 410. For example, the impedance calculation unit 400 may control the third switch 410 so that the third switch 410 alternately turns on and off according to a specified period.

[0043] The current control unit 500 can adjust the magnitude of the AC current flowing to the battery cell (B) via the third path 411 based on the result of comparing 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 an embodiment, the current control unit 500 can compare the voltage of the battery cell (B) with a 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 adjusts the resistance value of the variable resistor 520 based on the comparison result via the second comparator 510, thereby adjusting the magnitude of the AC current flowing through the third path 411. According to one embodiment, the current control unit 500 may set the variable resistor 520 to a first resistance value when the voltage of the battery cell (B) is equal to or greater than a second reference voltage. The current control unit 500 may 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 to 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 AC current can only flow through the first resistor 523.

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

[0049] Hereinafter, with reference to Figures 3a, 3b, and 3c, the connection relationships between components of the battery management device when the voltage of the battery cell (B) is within a first voltage range, a second voltage range, or a third voltage range will be described. Here, the first voltage range may refer to a range equal to or greater than a first reference voltage. The second voltage range may refer to a range equal to or greater than a second reference voltage that is lower than the first reference voltage and less than the first reference voltage. The third voltage range may refer to a range less than the second reference voltage.

[0050] FIG. 3a is a diagram illustrating the connections between components when the voltage of a battery cell is within a first voltage range, according to one embodiment. 3a, when the voltage of battery cell (B) is within a first voltage range, the battery management device may turn on first switch 210 and open second switch 220 to electrically connect battery cell (B) to impedance calculation unit 400 via first path 211, which does not include voltage amplifier 300. Furthermore, when the voltage of battery cell (B) is equal to or greater than a second reference voltage, the battery management device may open fourth switch 521 to allow AC current to flow through first resistor 523. In this case, impedance calculation unit 400 may calculate the impedance of battery cell (B) based on the first voltage applied via first path 211.

[0051] FIG. 3b illustrates a connection relationship between components when the voltage of a battery cell is within a second voltage range, according to one embodiment. 3b, when the voltage of battery cell (B) is within a second voltage range, the battery management device opens first switch 210 and conducts second switch 220, thereby electrically connecting battery cell (B) to impedance calculation unit 400 via second path 221 including voltage amplifier 300. Furthermore, when the voltage of battery cell (B) is equal to or greater than a second reference voltage, the battery management device opens fourth switch 521, allowing AC current to flow through first resistor 523. In this case, impedance calculation unit 400 can calculate the impedance of battery cell (B) based on the second voltage applied via second path 221. The second voltage may be a voltage amplified by voltage amplifier 300.

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

[0053] Meanwhile, in impedance measurement using a general comparator, some problems may occur when the battery cell voltage is not significantly different from the reference voltage. For example, when measuring the impedance of battery cell (B) using the battery management device of FIG. 2, assuming that the reference voltage of 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 is calculated via first path 211, which does not include voltage amplifier 300. If the cell voltage momentarily drops to 2.49V, the impedance is calculated via second path 221, which includes voltage amplifier 300. In this way, if the battery cell voltage is not significantly different from the reference voltage, repeated circuit switching due to noise may occur, resulting in large measurement errors.

[0054] To solve the above problem, according to one embodiment of the battery management device, the reference voltage of the first comparator 100 is 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 may adjust the first reference voltage based on a change in the voltage of the battery cell (B) during a predetermined time period. For example, the first comparator 100 may increase the first reference voltage (e.g., 2.5V) when the voltage of the battery cell (B) increases by a first specified level or more during the predetermined time period, and may decrease the first reference voltage (e.g., 2.5V) when the voltage of the battery cell (B) decreases by a second specified level or more during the predetermined time period.

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

[0057] 4 is a flowchart showing an operation method of a battery management device according to an 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 another form or structure.

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

[0059] In step S100, the battery management unit may 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 may be set in the range of 1 to 3 V. For example, the first reference voltage may be set to 2.5 V. The second reference voltage may be set lower than the first reference voltage. For example, the second reference voltage may be set to 1 V.

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

[0061] In step S200, the battery management unit can set an electrical connection path within the battery management unit based on the comparison result of step S100.

[0062] According to one embodiment, the battery management device may set the path for electrically connecting the battery cell (B) and the impedance calculation unit 400 to the first path 211 or the second path 221 based on the comparison result of step S100. According to one embodiment, the battery management device may 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, when the voltage of the battery cell (B) is equal to or higher than a first reference voltage. According to one embodiment, the battery management device may electrically connect the battery cell (B) and the impedance calculation unit 400 via the second path 221, which includes the voltage amplifier 300, when the voltage of the battery cell (B) is lower than the first reference voltage.

[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 may turn on a first switch 210 disposed on a first path 211 and turn off a second switch 220 disposed on a second path 221 including a voltage amplifier 300, thereby electrically connecting the battery cell (B) to 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 may turn off the first switch 210 disposed on the first path 211 and turn on a second switch 220 disposed on a second path 221 including a voltage amplifier 300, thereby electrically connecting the battery cell (B) to the impedance calculation unit 400 via the second path 221.

[0064] According to an embodiment, the battery management device may adjust the magnitude of the AC current flowing through the third path 411 to the battery cell (B) based on the comparison result of step (S100).

[0065] According to one embodiment, the battery management device can adjust the resistance value of the variable resistor 520 to adjust the magnitude of the AC current flowing through the third path 411 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 to 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, AC current can only flow through the first resistor 523.

[0068] According to one embodiment, when the voltage of the battery cell (B) is less than the second reference voltage, the battery management device can turn on the fourth switch 521. In this case, AC current can flow through the first resistor 523 and the second resistor 525 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 a change in the first voltage or a change in the second voltage. According to another embodiment, the battery management device can calculate the impedance of the battery cell (B) based on a differential value of the first voltage or a differential value of the second voltage.

[0070] The method for operating the battery management device according to the above embodiment may be implemented as an application or as program instructions executable by various computer components and recorded on a computer-readable recording medium, which may include program instructions, data files, data structures, and the like, singly or in combination.

[0071] According to the battery management device described above, it is not necessary to use different measuring devices depending on the operating voltage of the battery cell, and it is possible to easily measure the impedance of both general battery cells and low-voltage battery cells, and it is possible to obtain status information such as the degree of deterioration, remaining life, and presence or absence of abnormalities of the battery cell by utilizing Nyquist plots drawn according to the AC impedance response by frequency.

[0072] Although all components constituting the embodiments have been described as being combined into one or operating in combination, the present invention is not necessarily limited to such an embodiment, and all components may be selectively combined into one or more components within the intended scope. Furthermore, unless otherwise specified, the terms "comprise," "comprise," "have," and the like used above mean that the component in question can be contained therein, and therefore should not be interpreted as excluding other components, but as meaning that other components may further be included.

[0073] The above description is merely an illustrative example of the technical ideas disclosed in the present application, and a person having ordinary skill in the art to which the embodiments disclosed in the present application belong may make various modifications and variations within the scope that does not deviate from the essential characteristics of the embodiments disclosed in the present application.

[0074] Therefore, the embodiments disclosed in this application are intended to illustrate, not limit, the technical ideas disclosed in this application, and the scope of the technical ideas disclosed in this application is not limited by such embodiments. The scope of protection of the technical ideas disclosed in this application is to be interpreted by the scope of the claims below, and all technical ideas within the scope equivalent thereto are to be interpreted as being included in the scope of rights of this application.

Claims

1. a first comparator that compares the voltage of the battery cell with a first reference voltage; a switching circuit that sets a path electrically connecting the battery cell and the impedance calculation unit to a first path or a second path based on a comparison result by the first comparator; an impedance calculation unit that calculates the impedance of the battery cell based on the first voltage applied via the first path or the second voltage applied via the second path.

2. further comprising a voltage amplifier disposed 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 switching circuit a first switch disposed on the first path and a second switch disposed on the second path; When the voltage of the battery cell is equal to or higher than the first reference voltage, the first switch is turned on and the second switch is turned off, thereby setting the path to the first path; 2 . The battery management device according to claim 1 , wherein, when the voltage of the battery cell is lower than the first reference voltage, the first switch is opened and the second switch is brought into conduction, thereby setting the path to the second path.

4. The power supply further includes a third switch electrically connected to the battery cell, The battery management device according to claim 1 , wherein the third switch alternately turns on and off according to a specified cycle to generate an AC current to be 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 AC current based on a result of comparing the voltage of the battery cell with a second reference voltage.

6. the current control unit further includes a variable resistor disposed on a path through which the AC current flows; When the voltage of the battery cell is equal to or greater than the second reference voltage, the variable resistor is set to a first resistance value; The battery management device according to claim 5 , wherein when the voltage of the battery cell is lower than the second reference voltage, the variable resistor is set to a second resistance value that is smaller than the first resistance value.

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

8. The first comparator increasing the first reference voltage when the voltage of the battery cell increases by a first designated level or more within a predetermined time period; 8. The battery management device according to claim 7, wherein the first reference voltage is decreased when the voltage of the battery cell decreases by more than a second designated level in a predetermined time period.

9. comparing a voltage of the battery cell with a first reference voltage; setting a path electrically connecting the battery cell to an impedance calculation unit as a first path or a second path based on a result of comparing the voltage of the battery cell with the first reference voltage; 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. 10. The method of claim 9, further comprising: amplifying the voltage of the battery cell to the second voltage through a voltage amplifier disposed on the second path when the path is set to the second path.

11. 10. The method of claim 9, further comprising: 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) to be input to the battery cell.

12. The method of claim 11 , further comprising adjusting the magnitude of the AC current based on a 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 includes: setting a variable resistor disposed on a path through which the AC current flows to a first resistance value when the voltage of the battery cell is equal to or higher than the second reference voltage; 13. The method of claim 12, further comprising: when the voltage of the battery cell is lower than the second reference voltage, setting the variable resistor to a second resistance value that is lower than the first resistance value.

14. The method of claim 9 , further comprising adjusting the first reference voltage based on a change in the voltage of the battery cell during a predetermined time period.

15. The step of adjusting the first reference voltage includes: increasing the first reference voltage when the voltage of the battery cell increases by more than a first designated level for a predetermined time period; and decreasing the first reference voltage when the voltage of the battery cell decreases by more than a second designated level for a predetermined time period.

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