Battery diagnostic apparatus and method

Abstract

The present invention relates to a battery diagnosis apparatus and method, and the battery diagnosis apparatus according to an embodiment of the present invention may comprise: a measurement unit that measures cell impedances of a plurality of battery cells, a fixed impedance of at least one component, and a first module impedance of a battery module; and a control unit that determines an assembly state of the battery module based on the cell impedance, the fixed impedance, and the first module impedance.

Description

Technical Field

[0001] This application claims the benefit of Korean Patent Application No. 10-2022-0147410, filed with the Korean Intellectual Property Office on Nov. 7, 2022, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a diagnostic device and method for a battery, and more particularly, to a battery diagnostic device and method capable of diagnosing an assembled state. Background Art

[0003] In recent years, as the demand for portable electronic products such as laptop computers, cameras, and mobile phones has rapidly increased, and electric vehicles, energy storage batteries, robots, and satellites have begun to develop vigorously, extensive research has been conducted on secondary batteries used as their driving power sources.

[0004] A battery module can be formed by electrically connecting a plurality of battery cells. If the plurality of battery cells in the battery module are not correctly connected due to poor assembly, the performance and stability of the battery module may deteriorate.

[0005] Therefore, recently, a strategy for diagnosing a battery module to determine whether there is an assembly abnormality in the battery module is required. Summary of the Invention

[0006] Technical Problem

[0007] Embodiments of the present invention provide a battery diagnostic device and method capable of diagnosing an assembled state.

[0008] The technical aspects of the present invention are not limited to the above technical aspects, and other technical aspects not mentioned will be clearly understood by those skilled in the art from the following description.

[0009] Technical Solution

[0010] A diagnostic device for inspecting an assembled state of a battery module including at least one component and a plurality of battery cells according to an embodiment of the present invention may include: a measurement unit configured to measure cell impedances of the plurality of battery cells, a fixed impedance of the at least one component, and a first module impedance of the battery module; and a control unit configured to determine an assembled state of the battery module based on the cell impedances, the fixed impedance, and the first module impedance.

[0011] According to one embodiment, the control unit may calculate a second module impedance by adding the cell impedances and adding the fixed impedance to the sum thereof, and compare the first module impedance and the second module impedance to determine an assembled state of the battery module.

[0012] According to one embodiment, if the difference between the first module impedance and the second module impedance is within a threshold, the control unit may determine that the assembly state of the battery module is good, and if the difference between the first module impedance and the second module impedance exceeds the threshold, the control unit may determine that the assembly state of the battery module is defective.

[0013] According to one embodiment, the measuring unit may include: a cell measuring unit that measures the respective cell impedances of a plurality of battery cells; and a module measuring unit that measures the first module impedance of the battery module.

[0014] According to one embodiment, the module measuring unit may have a higher measurable voltage range than the cell measuring unit.

[0015] According to one embodiment, the module measuring unit may have the same measurable voltage range as the cell measuring unit.

[0016] According to one embodiment, the diagnostic device may further include a voltage distribution circuit that is electrically connected to the module measuring unit and the battery module and includes a plurality of resistors.

[0017] According to one embodiment, the voltage distribution circuit may distribute the voltage input from the battery module according to the resistance ratio of the plurality of resistors and supply the generated module voltage to the module measuring unit.

[0018] According to one embodiment, the diagnostic device may further include a memory in which a fixed impedance is stored, wherein the first module impedance and the cell impedance may vary with frequency, and the fixed impedance may have a fixed value that does not vary with frequency.

[0019] According to one embodiment, the cell measuring unit may initially charge and activate a plurality of battery cells, and then measure the cell impedance at a time point after a first time has elapsed, and the module measuring unit may measure the first module impedance at a time point after a second time has elapsed after activation.

[0020] According to one embodiment, the cell measuring unit may measure the direct current internal resistance (DCIR) of a plurality of battery modules, and then measure the cell impedance at a time point after a first period has elapsed, and the module measuring unit may measure the first module impedance at a time point after a second period has elapsed after measuring the direct current internal resistance (DCIR).

[0021] According to one embodiment, the first period may be the same period as the second period.

[0022] A diagnostic method for diagnosing an assembled state of a battery module including at least one component and a plurality of battery cells according to an embodiment of the present invention may include: measuring an impedance of each of the plurality of battery cells, a fixed impedance of at least one component, and a first module impedance of the battery module; and determining the assembled state of the battery module based on the impedance of each battery cell, the fixed impedance, and the first module impedance.

[0023] Advantageous Effects

[0024] According to an embodiment of the present invention, the assembled state of the battery module can be determined based on the impedance of each of the plurality of battery cells, the fixed impedance of at least one component, and the first module impedance of the battery module. Accordingly, it is possible to determine whether there is a defect in the assembly of the battery cells or whether there is a defect in the assembly of the battery module, and thus appropriate measures can be taken to improve safety.

[0025] In addition, various effects directly or indirectly identified through this document may be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a block diagram showing a diagnostic device for a battery according to a first embodiment of the present invention.

[0027] Figure 2 is a diagram showing Figure 1 another example of the measurement unit shown in

[0028] Figure 3 is a diagram showing Figure 1 a graph of the impedance of each battery cell measured by the cell measurement unit shown in

[0029] Figure 4 is a diagram showing Figure 1 a graph of the first module impedance measured by the module measurement unit shown in

[0030] Figure 5 is a flowchart showing a battery diagnostic method according to a first embodiment of the present invention.

[0031] Figure 6 is a block diagram showing a diagnostic device for a battery according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0032] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in various different forms and is not limited or restricted by the following embodiments.

[0033] To clearly explain the present invention, descriptions of parts irrelevant to the description or detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention are omitted, and when adding reference numerals to components in each drawing of this specification, the same or similar reference numerals are used for the same or similar components throughout the specification.

[0034] Furthermore, the terms and words used in this specification and claims should not be construed as limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts consistent with the technical idea of the present invention based on the inventor's ability to appropriately define the concept of the terms so as to explain his or her invention in the best possible way.

[0035] Diagnostic device according to the first embodiment

[0036] Figure 1 is a block diagram showing a diagnostic device for a battery according to a first embodiment of the present invention.

[0037] Refer to Figure 1 , the diagnostic device 100 can diagnose the assembled state of the battery module 200 after the assembly process of the battery module 200.

[0038] The battery module 200 may include a plurality of battery cells C1, C2,..., Cn and at least one component. Each of the plurality of battery cells C1, C2,..., Cn has a negative terminal and a positive terminal, and refers to an independent physically separable cell. The plurality of battery cells C1, C2,..., Cn included in the battery module 200 may be connected in series and / or in parallel.

[0039] The diagnostic device 100 can measure the impedance of each of the battery cells C1, C2,..., Cn and the battery module 200, and detect an assembly defect in the battery module based on the measured impedance. The diagnostic device 100 can supply an electrical signal to the assembled battery module 200, and then, after a predetermined time has elapsed, measure the impedance of each of the battery cells C1, C2,..., Cn and the battery module 200. As an example, the diagnostic device 100 can measure the impedance of each of the battery cells C1, C2,..., Cn and the battery module 200 after initially charging and activating the battery module 200. As another example, the diagnostic device 100 can measure the direct current internal resistance (DCIR) of the plurality of battery modules 20, and then measure the impedance of each of the battery cells C1, C2,..., Cn and the battery module 200.

[0040] According to an embodiment, the diagnostic device 100 may include a measurement unit 120, a control unit 130, and a memory 140.

[0041] The measurement unit 120 may include a single-cell measurement unit 121 and a module measurement unit 122 to measure the impedances CZ and MZ1 inside the battery module 200. For example, the measurement unit 120 may measure the impedances CZ and MZ1 by using electrochemical impedance spectroscopy (EIS).

[0042] The single-cell measurement unit 121 may be configured to measure the single-cell impedance CZ of each of the plurality of battery cells C1, C2, …, Cn. The single-cell measurement unit 121 may be configured to apply an alternating voltage to each of the plurality of battery cells C1, C2, …, Cn. The single-cell measurement unit 121 may be configured to apply an alternating voltage to each of the plurality of battery cells C1, C2, …, Cn while changing the frequency. For example, the single-cell measurement unit 121 may be configured to charge each of the plurality of battery cells C1, C2, …, Cn while applying an alternating voltage to each of the plurality of battery cells C1, C2, …, Cn, and measure the single-cell impedances CZ1, CZ2, …, CZn of each of the plurality of battery cells C1, C2, …, Cn during such a charging process.

[0043] The module measurement unit 122 may be configured to measure a first module impedance MZ1 of the battery module 200 including the plurality of battery cells C1, C2, …, Cn. The module measurement unit 122 may be configured to apply an alternating voltage to the battery module 200. The module measurement unit 122 may be configured to apply an alternating voltage to the battery module 200 while changing the frequency. For example, the module measurement unit 122 may be configured to charge the battery module 200 while applying an alternating voltage to the battery module 200, and measure the first module impedance MZ1 of the battery module 200 during such a charging process.

[0044] The module measurement unit 122 may have a higher measurable voltage range than the single-cell measurement unit 121. Since the module voltage of the battery module 200 input to the module measurement unit 122 is higher than the single-cell voltages of the battery cells C1, C2, …, Cn input to the single-cell measurement unit 121, the measurable voltage range of the module measurement unit 122 may be set high. For example, the single-cell measurement unit 121 may measure a single-cell impedance that is a low-voltage alternating current impedance less than 5V. The module measurement unit 122 may measure a first module impedance MZ1 that is a high-voltage alternating current impedance of 1000 V or less.

[0045] As an example, in the measurement unit 120, the single-cell measurement unit 121 and the module measurement unit 122 may be configured separately, as Figure 1 shown. As another example, the measurement unit 120 may be configured as a measurement unit that only includes the module measurement unit and omits the single-cell measurement unit, as Figure 2as shown in Figure 2 The measurement unit 120 shown in Figure 1 may have the same high measurable voltage range as the module measurement unit shown in Figure 2 Thus, the measurement unit 120 shown in

[0046] The memory 340 may store a fixed impedance FZ. The fixed impedance FZ may be the impedance of at least one component other than the plurality of battery cells C1, C2, …, Cn in the battery module 200. For example, the fixed impedance FZ may be calculated as the sum of the impedances of all components other than the plurality of battery cells C1, C2, …, Cn in the battery module 200. The fixed impedance FZ may have a fixed value that does not vary with frequency. The fixed impedance FZ may be a value obtained in advance by a previous measurement before measuring at least one of the cell impedance CZ and the first module impedance MZ1.

[0047] The control unit 130 may determine the assembled state of the battery module 200 based on the cell impedance CZ, the first module impedance MZ1, and the fixed impedance FZ. The control unit 130 may be connected to the measurement unit 120 and the memory 140 to be able to communicate with them in a wired manner and / or wirelessly.

[0048] The control unit 130 may include a calculation unit 131 and a determination unit 132. The calculation unit 131 and the determination unit 132 may be integrated into one component (e.g., a single chip), or may be implemented as multiple separate components (e.g., multiple chips).

[0049] The calculation unit 131 may receive the cell impedance CZ from the cell measurement unit 121, receive the first module impedance MZ1 from the module measurement unit 122, and receive the fixed impedance FZ from the memory 140. The calculation unit 131 may calculate a second module impedance MZ2 based on the received impedances CZ, MZ1, FZ.

[0050] The calculation unit 131 may sum the cell impedances CZ1, CZ2, …, CZn of the plurality of battery cells C1, C2, …, Cn, respectively, as shown in Equation 1, and calculate the second module impedance MZ2 by adding the fixed impedance FZ to the sum value.

[0051] [Equation 1]

[0052]

[0053] The determination unit 132 may detect an assembly defect of the battery module 200 by comparing the calculated second module impedance MZ2 with the first module impedance MZ1 measured by the module measurement unit 122.

[0054] The determination unit 132 can compare the first module impedance MZ1 and the second module impedance MZ2 to determine whether the difference between the first module impedance MZ1 and the second module impedance MZ2 is within a threshold value (e.g., an error range). If the difference between the first module impedance MZ1 and the second module impedance MZ2 is within the threshold value, the determination unit 132 can determine that no assembly defect has occurred in the battery module 200 and determine the battery module 200 as a good product. When the difference between the first module impedance MZ1 and the second module impedance MZ2 exceeds the threshold value, the determination unit 132 can determine that an assembly defect has occurred in the battery module 200 and determine that the battery module 200 is defective.

[0055] Figure 3 is a graph showing the single-cell impedance measured by the Figure 1 single-cell measurement unit shown in, and Figure 4 is a graph showing the first module impedance measured by the Figure 1 module measurement unit shown in. In Figure 3 , the horizontal axis can be considered as the real part Zrc of the single-cell impedance, and the vertical axis can be considered as the imaginary part Zic of the single-cell impedance. In Figure 4 , the horizontal axis can be considered as the real part Zrm of the first module impedance, and the vertical axis can be considered as the imaginary part Zim of the first module impedance. In Figure 3 and Figure 4 , the units of the horizontal axis and the vertical axis can be mΩ or Ω.

[0056] As Figure 3 shown in, the single-cell impedance can vary depending on the frequency of the AC signal applied to each of the plurality of battery cells C1, C2,..., Cn. As the frequency changes, the real part Zrc and the imaginary part Zic of the single-cell impedance change, and their intersection point is shown as an impedance point, which is a point on the coordinate, thereby deriving the single-cell impedance curve CCZ. The single-cell impedance of each of the plurality of battery cells C1, C2,..., Cn can derive the single-cell impedance curve CCZ or a plurality of single-cell impedance curves, at least one of which is different from the others.

[0057] The first module impedance can vary depending on the frequency of the AC signal applied to the battery module 200, as Figure 4 shown in. As the frequency changes, the real part Zrm and the imaginary part Zim of the first module impedance change, and their intersection point is shown as an impedance point, which is a point on the coordinate, thereby deriving the first module impedance curve CMZ.

[0058] Figure 5 is a flowchart showing a battery diagnosis method according to a first embodiment of the present invention.

[0059] In operation S11, a cell measurement unit (e.g., Figure 1 the cell measurement unit 121 in Figure 1 ) can measure the impedance of each of a plurality of battery cells (e.g., Figure 1 the battery cells C1, C2, …, Cn in Figure 2 ) within a few minutes. For example, the cell measurement unit can quickly measure the cell impedance within 1 to 3 minutes by using an EIS measurement scheme. The measured cell impedance can be stored in a memory (e.g., Figure 1 the memory 140 in

[0060] ) or transmitted to a control unit (e.g.,

[0061] the control unit 130 in

[0062] ). As an example, the cell impedance can be measured at a time point after a first predetermined period has elapsed after activating each of the plurality of battery cells. At the same time, after assembling the battery cells in a discharged state, the battery cells can be activated by initial charging. Figure 1 In operation S12, a module measurement unit (e.g.,

[0063] the module measurement unit 122 in

[0064] ) can measure a first module impedance MZ1 of a battery module assembled to include at least one component and a plurality of battery cells within a few minutes. For example, the module measurement unit can quickly measure the module impedance within 1 to 3 minutes by using an EIS measurement scheme. The measured module impedance can be transmitted to the control unit. As an example, the first module impedance MZ1 can be measured at a time point after a second predetermined period has elapsed after activating the battery module. The second period can be the same as the first period. At the same time, after assembling the battery module in a discharged state, the battery module can be activated by initial charging. As another example, the first module impedance MZ1 can be measured at a time point after a predetermined second period has elapsed after measuring the direct current internal resistance (DCIR) of the battery module. The second period can be the same as the first period. The first period and the second period can be from several seconds to several minutes. For example, the first period and the second period can be 30 seconds.

[0065] In operation S13, the control unit can calculate a second module impedance MZ2 by adding the measured cell impedance to a fixed impedance stored in the memory. The fixed impedance can be the impedance of at least one component included in the battery module. The at least one component can be a component other than the plurality of battery cells included in the battery module.

[0066] In operation S14, the control unit may compare the measured first module impedance MZ1 and the calculated second module impedance MZ2. The control unit may determine whether the difference between the measured first module impedance MZ1 and the calculated second module impedance MZ2 is included within a threshold value.

[0067] In operation S15, if as a result of the comparison the difference between the first module impedance MZ1 and the second module impedance MZ2 is within a preset threshold value, the control unit may determine that there is no assembly defect in the battery module. Accordingly, the control unit may determine that the battery module is a good product.

[0068] In operation S16, if as a result of the comparison the difference between the first module impedance MZ1 and the second module impedance MZ2 is outside the threshold value (or exceeds the threshold value), the control unit may determine that there is an assembly defect in the battery module. Accordingly, the control unit may determine that the battery module is defective.

[0069] According to an embodiment, the single cell impedance and the first module impedance MZ1 may be measured separately as described above. For example, the single cell impedance may be measured after placing a plurality of battery cells. Then, after forming a battery module by assembling a plurality of battery cells and at least one component, the first module impedance MZ1 may be measured.

[0070] According to an embodiment, the single cell impedance and the first module impedance MZ1 may be measured simultaneously. The single cell impedance and the first module impedance MZ1 may be measured after forming a battery module by assembling a plurality of battery cells and at least one component.

[0071] Diagnostic device according to a second embodiment

[0072] Figure 6 is a block diagram showing a diagnostic device for a battery according to a second embodiment of the present invention.

[0073] Referring to Figure 6 , except that the diagnostic device according to the second embodiment of the present invention further includes a voltage distribution circuit 150, it has the same components as the diagnostic device shown in Figure 1 . Accordingly, the previous description may be applied to the same configurations and / or operations among the configurations and / or operations of the above-described diagnostic device.

[0074] The measurable voltage range of the module measurement unit 122 may be the same as or similar to the measurable voltage range of the single cell measurement unit 121. The measurable voltage range of the module measurement unit 122 may be the same as or similar to the cell voltages of a plurality of battery cells C1, C2, …, Cn. It is difficult to measure the module impedance of the battery module 200 whose module voltage is higher than the cell voltages of the battery cells C1, C2, …, Cn by the module measurement unit 122. Therefore, the adjusted voltage dropped by the voltage distribution circuit 150 connected to the front end of the module measurement unit 122 may be transmitted to the module measurement unit 122. The voltage distribution circuit 150 may be electrically connected between the battery module 200 and the module measurement unit 122.

[0075] The voltage distribution circuit 150 may be formed to include a plurality of resistors and have a resistance ratio for distributing the module voltage of the battery module 200. The voltage distribution circuit 150 may reduce the module voltage to an adjusted voltage measurable by the module measurement unit 122 according to the resistance ratio of the plurality of resistors.

[0076] The resistance ratio of the plurality of resistors may be a value pre-obtained by previous measurements before performing the diagnostic device (before measuring the cell impedance). The resistance ratio may be set by a plurality of previous measurements such that the difference between the first module impedance (MZ1) and the second module impedance (MZ2) is included within a threshold. For example, the resistance ratio may be set such that the first module impedance MZ1 and the second module impedance MZ2 have the same value.

[0077] The module measurement unit 122 may measure the first module impedance by using the adjusted voltage dropped by the voltage distribution circuit. Even if the dropped adjusted voltage is input through the voltage distribution circuit, the module measurement unit 122 may identify the voltage as the module voltage before the voltage drop and derive the first module impedance MZ1 corresponding to the module voltage.

[0078] The above battery diagnostic device according to the present invention may be applied to a battery pack. In addition to the above diagnostic device, the battery pack according to the present invention may further include components typically included in a battery pack, such as one or more secondary batteries, a battery management system (BMS), a current sensor, a relay, a fuse, a pack housing, etc. The diagnostic device may target a plurality of battery cells and a plurality of battery modules included in the battery pack. At least some functions or operations of the control unit and the memory included in the diagnostic device may be implemented by the BMS.

[0079] The above battery pack may be applied to various devices. The battery pack may be applied to transportation means such as electric bicycles, electric vehicles, and hybrid vehicles, but is not limited thereto, and may be applied to various devices in which the battery pack can be used.

[0080] The above-described diagnostic device and method are not limited to the embodiments described in each figure and can be implemented in various different forms. For example, the diagnostic device can be applied to the inspection process before the product leaves the factory. For example, the diagnostic device can be applied to the inspection process after the product leaves the factory. Defective connections weakened due to long-term use of battery packs applied to various devices can be diagnosed.

[0081] The above-described diagnostic device and method are not limited to the embodiments described in each drawing, and the structures described in each drawing can be combined and applied. As an example, the diagnostic device and method according to the present invention can measure the cell impedance and the first module impedance after activation or DC internal resistance measurement as described above. As another example, the diagnostic device and method according to the present invention can measure the cell impedance and the first module impedance after activation, and re-measure the cell impedance and the first module impedance after measuring the DC internal resistance.

[0082] Although the present invention has been described above using limited examples and drawings, the present invention is not limited thereto, and those skilled in the art to which the present invention pertains can make various implementations within the equivalent scope of the technical concept of the present invention and within the scope of the described claims.

[0083] [Description of Reference Numerals]

[0084] 100: Diagnostic device

[0085] 120: Measurement unit

[0086] 121: Cell measurement unit

[0087] 122: Module measurement unit

[0088] 130: Control unit

[0089] 131: Calculation unit

[0090] 132: Determination unit

Claims

1. A diagnostic device for checking the assembled state of a battery module including at least one component and a plurality of battery cells, the diagnostic device comprising: a measurement unit that measures the individual impedance of the plurality of battery cells, the fixed impedance of the at least one component, and a first module impedance of the battery module; and a control unit that determines the assembled state of the battery module based on the individual impedance, the fixed impedance, and the first module impedance.

2. The diagnostic device according to claim 1, wherein the control unit calculates a second module impedance by adding the individual impedances and adding the fixed impedance to the sum thereof, and compares the first module impedance and the second module impedance to determine the assembled state of the battery module.

3. The diagnostic device according to claim 2, wherein, if the difference between the first module impedance and the second module impedance is within a threshold, the control unit determines that the assembled state of the battery module is good, and if the difference between the first module impedance and the second module impedance exceeds the threshold, the control unit determines that the assembled state of the battery module is defective.

4. The diagnostic device according to claim 2, wherein the measurement unit comprises: an individual measurement unit that measures the respective individual impedances of the plurality of battery cells; and a module measurement unit that measures the first module impedance of the battery module.

5. The diagnostic device according to claim 4, wherein the module measurement unit has a higher measurable voltage range than the individual measurement unit.

6. The diagnostic device according to claim 4, wherein the module measurement unit has the same measurable voltage range as the individual measurement unit.

7. The diagnostic device according to claim 6, further comprising: a voltage distribution circuit that is electrically connected to the module measurement unit and the battery module and includes a plurality of resistors.

8. The diagnostic device according to claim 7, wherein the voltage distribution circuit distributes the voltage input from the battery module according to the resistance ratio of the plurality of resistors and supplies the generated module voltage to the module measurement unit.

9. The diagnostic device according to claim 1, further comprising a memory in which the fixed impedance is stored, wherein the first module impedance and the individual impedance vary with frequency, and the fixed impedance has a fixed value that does not vary with frequency.

10. The diagnostic device according to claim 4, wherein the individual measurement unit initially charges and activates the plurality of battery cells, and then measures the individual impedance at a time point after a first time has elapsed, and the module measurement unit measures the first module impedance at a time point after a second time has elapsed after the activation.

11. The diagnostic device according to claim 4, wherein the individual measurement unit measures the direct current internal resistance (DCIR) of the plurality of battery modules, and then measures the individual impedance at a time point after the elapse of a first period, and the module measurement unit measures the first module impedance at a time point after the elapse of a second period after measuring the direct current internal resistance (DCIR).

12. The diagnostic device according to claim 10 or 11, wherein the first period is the same period as the second period.

13. A diagnostic method for diagnosing an assembled state of a battery module including at least one component and a plurality of battery cells, the method comprising: measuring the individual impedance of the plurality of battery cells, the fixed impedance of the at least one component, and the first module impedance of the battery module; and determining the assembled state of the battery module based on the individual impedance, the fixed impedance, and the first module impedance.

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