Battery diagnostic device and method

Abstract

According to one aspect of the present invention, a battery diagnostic device may include: a measurement unit configured to measure a voltage value of the battery at predetermined intervals while the battery is being charged; and a processor configured to calculate a resistance value of the battery based on the measured voltage values ​​of the battery, compare the calculated resistance values ​​with a preset reference profile to determine a resistance change pattern, and determine a state of the battery based on the determined resistance change pattern.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2022-0071950, filed on June 14, 2022, and the entire contents disclosed in the specification and drawings of that application are incorporated herein by reference.

[0002] The present invention relates to a battery diagnostic device and method, and more particularly to a device and method for diagnosing the state of a battery. [Background technology]

[0003] Recently, the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased dramatically, and the development of electric vehicles, energy storage batteries, robots, satellites, etc. has been gaining momentum. Accordingly, research into high-performance batteries that can be repeatedly charged and discharged is being actively conducted.

[0004] Currently commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are attracting attention due to their advantages of being able to be freely charged and discharged since they have almost no memory effect compared to nickel-based batteries, an extremely low self-discharge rate, and a high energy density.

[0005] While much research has been conducted on these batteries from the viewpoints of increasing capacity and density, improving lifespan and safety are also important. To achieve these goals, it is necessary to suppress the decomposition reaction between the electrolyte and the electrode surface, and to prevent overcharging and overdischarging.

[0006] In particular, overhangs, which are misaligned between the positive and negative electrodes, can occur during the battery manufacturing process. These overhangs can be one of the causes of lithium deposition on the negative electrode surface (lithium plating). Lithium deposition on the negative electrode surface can cause side reactions with the electrolyte and changes in the battery's kinetic balance, resulting in battery degradation. Furthermore, the deposition of lithium metal on the negative electrode surface can cause an internal short circuit in the battery, posing a risk of fire and explosion due to the internal short circuit.

[0007] Therefore, there is a need to develop a technology that can diagnose the state of a battery taking into account the presence or absence of an overhang and / or the extent of the overhang. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a battery diagnostic device and method for diagnosing the state of a battery having an overhang.

[0009] Other objects and advantages of the present invention can be understood from the following description and will become more apparent from the embodiments of the present invention. Also, it will be easily understood that the objects and advantages of the present invention can be realized by the means recited in the claims and their combinations. [Means for solving the problem]

[0010] According to one aspect of the present invention, a battery diagnostic device may include: a measurement unit configured to measure a voltage value of the battery at predetermined intervals while the battery is being charged; and a processor configured to calculate a resistance value of the battery based on the measured voltage values ​​of the battery, compare the calculated resistance values ​​with a preset reference profile to determine a resistance change pattern, and determine a state of the battery based on the determined resistance change pattern.

[0011] Here, the reference profile may be a profile indicating a change in a plurality of resistance values ​​calculated during the charging process of the reference battery for each predetermined period.

[0012] The processor may also be configured to generate a resistance profile indicating changes in the calculated plurality of resistance values, compare the generated resistance profile with the reference profile, and determine the resistance change pattern as a first resistance change pattern or a second resistance change pattern.

[0013] The processor may also be configured to calculate a first slope in the resistance profile, calculate a second slope in the reference profile, and determine the resistance change pattern based on the result of comparing the first slope with the second slope.

[0014] The processor may also be configured to determine the resistance change pattern as the first resistance change pattern if a first slope at the end of charging on the resistance profile is less than a second slope at the end of charging on the reference profile, and to determine the resistance change pattern as the second resistance change pattern if the first slope is greater than or equal to the second slope.

[0015] The processor may also be configured to determine the resistance change pattern as the first resistance change pattern if a first slope based on a first point on the resistance profile corresponding to the end of charging and a second point different from the first point is less than a second slope based on a third point on the reference profile corresponding to the first point and a fourth point corresponding to the second point, and to determine the resistance change pattern as the second resistance change pattern if the first slope is greater than or equal to the second slope.

[0016] The processor may also be configured to generate an SOC-resistance profile indicating a correspondence relationship between the SOC of the battery and the calculated resistance value while the battery is being charged, determine a target resistance value corresponding to a predetermined SOC in the SOC-resistance profile, and determine a point in the resistance profile corresponding to the target resistance value as the second point.

[0017] The processor may also be configured to determine a reference resistance value corresponding to the predetermined SOC in a reference SOC-resistance profile corresponding to the reference profile, and to determine a point in the reference profile corresponding to the reference resistance value as the fourth point.

[0018] The processor may also be configured to determine a peak belonging to a predetermined SOC interval in a differential profile corresponding to the SOC of the battery and the voltage value of the battery, and determine the SOC corresponding to the determined peak as the predetermined SOC.

[0019] The processor may also be configured to determine that the battery is in a defective state when the resistance change pattern is the first resistance change pattern, and to determine that the battery is in a normal state when the resistance change pattern is the second resistance change pattern.

[0020] The processor may also be configured to charge the battery by repeatedly changing the charging current value of the battery at predetermined intervals, and to calculate the resistance value based on the change in voltage value while the charging current value of the battery corresponds to the predetermined value.

[0021] In order to achieve the above object, a battery pack according to another aspect of the present invention may include the battery diagnostic device according to the present invention.

[0022] In order to achieve the above object, according to another aspect of the present invention, a vehicle may include the battery diagnostic device according to the present invention.

[0023] In addition, to achieve the above-mentioned object, according to yet another aspect of the present invention, a battery diagnosis method may include a voltage value measurement step of measuring a voltage value of the battery at predetermined intervals while the battery is being charged; a resistance value calculation step of calculating a resistance value of the battery based on the measured voltage values ​​of the battery; a resistance change pattern determination step of determining a resistance change pattern by comparing the calculated resistance values ​​with a preset reference profile; and a battery state determination step of determining a state of the battery based on the determined resistance change pattern. [Effects of the Invention]

[0024] According to one aspect of the present invention, it is possible to diagnose a defective battery in which lithium has been precipitated due to an overhang that occurred during the manufacturing process.

[0025] In addition, according to one embodiment of the present invention, there is an advantage that a defective battery in which lithium has been precipitated due to an overhang can be quickly determined based only on the change pattern of the resistance value obtained during the charging process of the battery.

[0026] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the claims.

[0027] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concepts of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram illustrating an exemplary battery diagnostic device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram showing an example of a charging current applied to a battery during the charging process of the battery. [Figure 3] 4A and 4B are diagrams showing an example of a reference voltage profile indicating the voltage value of a reference battery and a reference profile indicating the resistance value of the reference battery during charging of the reference battery; [Figure 4] 10 is a graph illustrating an example of a processor using a resistance profile to determine a resistance change pattern according to an embodiment of the present invention. [Figure 5] 6 is a graph illustrating an example of a processor using a resistance profile to determine a resistance change pattern according to various embodiments of the present invention. [Figure 6] 4 is a graph showing an example of an SOC-resistance profile and a reference SOC-resistance profile according to one embodiment of the present invention. [Figure 7] FIG. 2 is a diagram illustrating an example of a differential profile showing the correspondence between differential voltage and SOC based on the SOC and voltage of a battery. [Figure 8] 1 is a diagram illustrating an example of a battery pack including a battery diagnostic device according to the present invention; [Figure 9] 1 is a diagram illustrating an example of a vehicle including a battery diagnostic device according to the present invention; [Figure 10] 3 is a flowchart illustrating a battery diagnostic method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0030] Therefore, it should be understood that the configurations shown in the embodiments described in this specification are merely the most desirable embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0031] Furthermore, in describing the present invention, if it is determined that a detailed description of related known structures or functions would obscure the gist of the present invention, the detailed description will be omitted.

[0032] Terms including ordinal numbers, such as first, second, etc., are used to distinguish one of the various components from the rest, and are not used to limit the components by such terms.

[0033] Throughout the specification, when a part is said to "comprise" certain elements, this means that it can further include other elements, rather than excluding other elements, unless specifically stated to the contrary.

[0034] Throughout this specification, when a part is said to be "connected" to another part, this includes not only the case where the part is "directly connected" but also the case where the part is "indirectly connected" via another element between them.

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0036] FIG. 1 is a diagram illustrating an exemplary battery diagnostic device 100 according to an embodiment of the present invention.

[0037] Referring to FIG. 1, a battery diagnostic device 100 may include a measurement unit 110, a processor 120, and a memory .

[0038] The measuring unit 110 may be configured to measure the voltage value of the battery at predetermined intervals while the battery is being charged. Herein, the term "battery" refers to a single independent cell that has a negative terminal and a positive terminal and can be physically separated. As an example, a lithium ion battery or a lithium polymer battery may be considered as a battery. The term "battery" may also refer to a battery module in which multiple cells are connected in series and / or parallel. For convenience of explanation, the term "battery" will be described below as referring to a single independent cell.

[0039] The measuring unit 110 may employ various voltage measuring techniques known at the time of filing of the present invention. For example, the measuring unit 110 may include a voltage sensor known at the time of filing of the present invention. In particular, when the battery diagnostic device 100 according to the present invention is applied to a battery pack, a voltage sensor already provided in the battery pack may be used as the measuring unit 110 according to the present invention.

[0040] The measuring unit 110 may measure the voltage value of the battery at predetermined intervals during charging of the battery under the control of the processor 120. Specifically, the processor 120 may charge the battery by controlling a charging current to be applied to the battery. For example, the processor 120 may apply a charging current to the battery in the form of pulses.

[0041] The processor 120 may charge the battery by repeatedly changing the charging current value of the battery at predetermined intervals. FIG. 2 illustrates an example of a charging current applied to the battery during charging. The x-axis of the graph in FIG. 2 represents time, and the y-axis represents the charging current value. The processor 120 may charge the battery with a first current value I1 and apply a pulse current of a second current value I2 to the battery at predetermined intervals. That is, a current of the second current value I2 may be applied to the battery from the first time t1 to the second time t2, from the third time t3 to the fourth time t4, and from the fifth time t5 to the sixth time t6, and a current of the first current value I1 may be applied to the battery from the second time t2 to the third time t3 and from the fourth time t4 to the fifth time t5. Here, the predetermined interval during which the pulse current is applied may be a first period p1, and the duration during which the pulse current is applied may be a first time interval d1. The duration for which the pulse current is applied may correspond to various values, such as 0.1 seconds, 0.5 seconds, or 1 second. Alternatively, in various embodiments, the processor 120 may set the charging current to have a pause period during which the current is zero. For example, although not shown in FIG. 2 , a current of a predetermined magnitude may be applied to the battery from the first time t1 to the second time t2, from the third time t3 to the fourth time t4, and from the fifth time t5 to the sixth time t6, and the current value may be zero from the second time t2 to the third time t3 and from the fourth time t4 to the fifth time t5. For convenience of explanation, the following description will be given assuming that the battery is charged without any pause periods.

[0042] The processor 120 may calculate the resistance value based on a change in the voltage value while the battery's charging current value corresponds to a predetermined value. Specifically, the measurement unit 110 may measure the voltage value of the battery at each start time and end time of application of a second current value I2 when a pulse current is applied to the battery at each predetermined period. For example, the measurement unit 110 may measure the voltage value of the battery at a first time t1 and at a second time t2. Thereafter, the measurement unit 110 may measure the voltage value of the battery again at a third time t3 and at a fourth time t4, thereby measuring the voltage value of the battery at each predetermined period (e.g., first period p1). The measurement unit 110 may transmit the measured voltage value to the processor 120. The processor 120 may calculate the resistance value based on the change in the voltage value.

[0043] The processor 120 can acquire the voltage value of the battery measured by the measurement unit 110. The processor 120 can calculate the resistance value of the battery based on the measured voltage value of the battery. Specifically, the processor 120 can calculate the resistance value of the battery at predetermined cycles (e.g., first cycle p1) while the battery is being charged. The processor 120 can calculate the voltage difference of the battery and divide the calculated voltage difference by the charging current value to calculate the resistance value of the battery at predetermined cycles.

[0044] As described with reference to FIG. 2, the processor 120 may calculate the resistance of the battery using the measured voltage of the battery. Specifically, the processor 120 may calculate the difference between a first voltage corresponding to the voltage of the battery at a first time t1 and a second voltage corresponding to the voltage of the battery at a second time t2. The processor 120 may calculate the resistance of the battery using Ohm's law (R=ΔV÷ΔI). For example, the processor 120 may calculate the resistance by dividing the calculated voltage difference (e.g., ΔV) by the amount of current applied between the first time t1 and the second time t2 (e.g., ΔI=I2×(t2−t1)). The processor 120 may calculate the resistance of the battery at predetermined intervals using the above method to calculate a plurality of resistance values. For example, the resistance calculated by the processor 120 may correspond to DCIR (Direct Current Internal Resistance).

[0045] The processor 120 can determine a resistance change pattern by comparing the calculated resistance values ​​with a preset reference profile. Here, the reference profile may be a profile showing changes in resistance values ​​extracted by previously performing a charging process on a battery of the same type as the battery to be diagnosed or a battery designed to have the same characteristics (hereinafter, referred to as a reference battery). The reference profile may be pre-stored in the memory 130.

[0046] 3 illustrates an example of a reference voltage profile Vr showing the voltage value of a reference battery during charging, and a reference profile Rr showing the resistance value of the reference battery. For example, in the embodiment of FIG. 3, the reference voltage profile Vr can be represented as an XY graph with the X axis representing time and the Y axis representing voltage. Similarly, the reference profile Rr can be represented as an XY graph with the X axis representing time and the Y axis representing voltage.

[0047] The reference profile Rr may be a profile showing changes in multiple resistance values ​​calculated during the charging process of the reference battery at predetermined intervals. The reference profile Rr may be a graph showing resistance values ​​of the reference battery calculated under the same conditions so that the processor 120, described below, can compare them with the resistance values ​​of the battery to be diagnosed. For example, the reference profile Rr may be a graph showing resistance values ​​calculated using voltage values ​​of the reference battery measured for the same measurement time and measurement interval when the reference battery is charged with a charging current of the same magnitude as that of the battery to be diagnosed, as in the method described with reference to FIG. 2. Meanwhile, for convenience of explanation, FIG. 3 shows the reference voltage profile Vr and the reference profile Rr on a single plane.

[0048] Referring to the reference voltage profile Vr of the reference battery, it can be seen that the voltage value of the reference battery gradually increases during charging of the reference battery until the time tf when charging ends. Referring to the reference profile Rr of the reference battery, it can be seen that the resistance value of the reference battery gradually decreases during charging of the reference battery from the start of charging until the time tf when charging ends.

[0049] The processor 120 can determine a resistance change pattern by comparing a plurality of resistance values ​​with the reference profile, as described with reference to Fig. 2. Specifically, the processor 120 can compare the slope of the reference profile based on a specific point with the slope of a profile indicating changes in the resistance value of the battery to be diagnosed.

[0050] The processor 120 can determine the state of the battery based on the determined resistance change pattern.

[0051] When the resistance change pattern is determined to be the first resistance change pattern, the processor 120 may determine that the state of the battery being diagnosed is a defective state. Here, the first resistance change pattern may be a pattern having a slope less than the slope of the reference profile. Specifically, when an overhang occurs in the battery, lithium may be deposited on the negative electrode, resulting in a pattern in which the resistance value decreases at the end of the charging process. Preferably, when an overhang greater than a reference rate occurs in the battery, a pattern in which the resistance decreases at the end of the charging process may occur. When the resistance change pattern is determined to be the first resistance change pattern, the processor 120 may determine that the state of the battery is a defective state in which an overhang has occurred.

[0052] For example, the reference ratio can be set to a value of 3% or more. Preferably, the reference ratio can be set to any value between 3% and 5%. However, it should be noted that the reference ratio is not limited to the above-mentioned exemplary numerical values.

[0053] When the resistance change pattern is determined to be the second resistance change pattern, the processor 120 can determine that the state of the battery being diagnosed is normal. Here, the second resistance change pattern can be a pattern having a slope equal to or greater than the slope of the reference profile.

[0054] That is, the battery diagnostic device 100 according to an embodiment of the present application can specifically classify the resistance change pattern of the battery during the charging process into a first resistance change pattern or a second resistance change pattern. Also, the battery diagnostic device 100 can diagnose the battery state based on the resistance change pattern of the battery. Therefore, the battery diagnostic device 100 has an advantage of being able to quickly diagnose the battery state during the charging process.

[0055] The following figures are used to describe various embodiments in which the processor 120 determines the resistance change pattern.

[0056] The processor 120 is operatively connected to other components of the battery diagnostic apparatus 100 and can control various operations of the battery diagnostic apparatus 100. The processor 120 can perform various operations of the battery diagnostic apparatus 100 by executing one or more instructions stored in the memory 130. The processor 120 can include, as needed, a processor 120, an application-specific integrated circuit (ASIC), a chipset, a logic circuit, a register, a communication modem, a data processing device, and the like known in the art to perform various control logic performed in the present invention. Furthermore, when the control logic is realized in software, the processor 120 can be realized as a collection of program modules. In this case, the program modules can be stored in the memory 130 and executed by the processor 120.

[0057] In particular, when the battery diagnostic device 100 according to the present invention is implemented in a form that is included in a battery pack, the battery pack may include a control device referred to as a microcontroller unit (MCU) or a battery management system (BMS). In this case, the processor 120 may be implemented by a component such as an MCU or BMS that is included in such a general battery pack. Furthermore, in this specification, the terms "to perform" or "configured to perform" with respect to the operation or function of the processor 120 may also include the meaning of "programmed to perform."

[0058] The memory 130 may be configured to store predetermined data. In particular, in the present invention, the memory 130 may pre-store a reference profile. The reference profile may be a profile that serves as a reference for comparison with the resistance value of the battery to be diagnosed. That is, the reference profile may correspond to the transition of the resistance value calculated using the charging current value by measuring the voltage value of the reference battery during charging in the same manner as that used to calculate the voltage value of the battery to be diagnosed. As an example, the reference profile has already been described with reference to FIG. 3, so a repeated description will be omitted.

[0059] The memory 130 may store data and programs necessary for each component of the battery diagnostic device 100 to operate and function, or data generated during the operation and function. The memory 130 may be located inside or outside the processor 120 and connected to the processor 120 by various known means. The memory 130 may store at least one program, application, data, or instructions to be executed by the processor 120. The type of the memory 130 is not particularly limited as long as it is a known information storage means capable of recording, erasing, updating, and reading data. The memory 130 may be implemented as at least one of a flash memory type, a hard disk type, a solid state disk (SSD) type, a solid disk drive (SDD) type, a multimedia card micro type, a random access memory (RAM), a static RAM (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), and a programmable read-only memory (PROM), but the present invention is not necessarily limited to these specific memory types. The memory 130 may also store program code that defines processes that can be executed by the processor 120 .

[0060] According to this configuration of the present invention, the battery condition can be easily diagnosed based on the change in resistance at the end of the battery charging process. Various embodiments in which the processor 120 determines the battery condition using the resistance change pattern will be described with reference to the following drawings.

[0061] The processor 120 can generate a resistance profile showing changes in the calculated resistance values, as will be explained in more detail with reference to FIG.

[0062] 4 is a graph showing an example in which the processor 120 determines a resistance change pattern using a resistance profile according to an embodiment of the present invention. In this embodiment and other embodiments described below, differences from the above will be mainly described, and detailed descriptions of parts to which the same or similar descriptions can be applied will be omitted.

[0063] 4, a reference profile Rr for a reference battery is shown, as described in FIG 2. Here, the processor 120 can calculate a plurality of resistance values ​​using voltage values ​​measured at predetermined cycles of the battery to be diagnosed, and generate a resistance profile Rd indicating a change pattern of the calculated plurality of resistance values.

[0064] The processor 120 can compare the generated resistance profile Rd with the reference profile Rr to determine the resistance change pattern as the first resistance change pattern or the second resistance change pattern.

[0065] Specifically, the processor 120 can compare the slope of the resistance profile Rd with the reference profile Rr to determine the resistance change pattern in order to improve the accuracy of the battery diagnosis.

[0066] For example, the processor 120 can determine the resistance change pattern as the first resistance change pattern or the second resistance change pattern depending on the slope of the resistance profile Rd.

[0067] The processor 120 can calculate a first slope in the resistance profile Rd and a second slope in the reference profile Rr. The processor 120 can also determine a resistance change pattern based on the results of comparing the first slope and the second slope. The processor 120 can calculate the first slope by recognizing the instantaneous slope at a predetermined point in the resistance profile Rd. The processor 120 can calculate the second slope by recognizing the instantaneous slope at a point in the reference profile Rr corresponding to the predetermined point. If the first slope is less than the second slope, the processor 120 can determine the resistance change pattern as the first resistance change pattern. If the first slope is equal to or greater than the second slope, the processor 120 can determine the resistance change pattern as the second resistance change pattern. This will be described in more detail with reference to FIG. 4.

[0068] The processor 120 can determine the resistance change pattern as a first resistance change pattern if the first slope at the time tf when charging ends on the resistance profile Rd is less than the second slope at the time tf when charging ends on the reference profile Rr. The first slope at the time tf when charging ends on the resistance profile Rd can correspond to the instantaneous slope at the time tf when charging ends. Also, the second slope at the time tf when charging ends on the reference profile Rr can correspond to the instantaneous slope at the time tf when charging ends.

[0069] 4, a tangent line Rda at the time tf at which charging ends on the resistance profile Rd and a tangent line Rra at the time tf at which charging ends on the reference profile Rr are shown. Because a first slope corresponding to the slope of the tangent line Rda is less than a second slope corresponding to the slope of the tangent line Rra, the processor 120 can determine the resistance change pattern as the first resistance change pattern. In various embodiments, if the difference between the first slope and the second slope exceeds a predetermined range, the processor 120 can also determine the resistance change pattern as the first resistance change pattern.

[0070] When the resistance change pattern is the first resistance change pattern, the processor 120 can determine that the battery state is poor.

[0071] For example, the first resistance change pattern may be a pattern in which the first slope is less than the second slope and the resistance value of the battery decreases.

[0072] As another example, the first resistance change pattern may be a pattern in which the first slope is less than the second slope and the difference between the first slope and the second slope is equal to or greater than a threshold. The processor 120 may calculate the difference by calculating the formula "second slope - first slope." Furthermore, the processor 120 may determine the resistance change pattern as the first resistance change pattern if the calculated difference is equal to or greater than a preset threshold.

[0073] The processor 120 may diagnose a battery determined to have the first resistance change pattern as a defective battery, that is, as an abnormal battery in which the overhang is greater than or equal to a reference ratio.

[0074] The processor 120 can determine the resistance change pattern to be the second resistance change pattern if the first slope of the point tf at which charging ends on the resistance profile Rd is greater than or equal to the second slope of the point tf at which charging ends on the reference profile Rr.

[0075] For example, the second resistance change pattern may be a pattern in which the first slope is equal to or greater than the second slope. If the first slope decreases but is equal to or greater than the second slope, the processor 120 may determine that the resistance change pattern is the second resistance change pattern.

[0076] As another example, when the first slope is less than the second slope, but the difference between the first slope and the second slope is less than a threshold, the processor 120 may determine the resistance change pattern as the second resistance change pattern. The processor 120 may calculate the difference by calculating the formula "second slope - first slope." Furthermore, the processor 120 may determine the resistance change pattern as the second resistance change pattern when the calculated difference is less than a preset threshold. That is, when the first slope is less than the second slope, but the decrease in the first slope is less than a certain level compared to the second slope, the processor 120 may determine the resistance change pattern as the second resistance change pattern.

[0077] When the resistance change pattern is the second resistance change pattern, the processor 120 can determine that the battery is in a normal state. Specifically, the processor 120 can diagnose a battery determined to have the second resistance change pattern as a normal battery. That is, the processor 120 can diagnose a battery determined to have the second resistance change pattern as a normal battery in which an overhang has not occurred. Alternatively, the processor 120 can diagnose a battery determined to have the second resistance change pattern as a normal battery in which an overhang less than a reference ratio has occurred. In this way, the processor 120 can diagnose whether an overhang has occurred in the battery during charging based only on the resistance change pattern at the end of charging.

[0078] The battery diagnostic device 100 according to an embodiment of the present invention can subdivide the resistance change pattern of the battery based on the increase or decrease in the first slope and the difference between the first slope and the second slope. Furthermore, the battery diagnostic device 100 can diagnose the battery state based on the subdivided resistance change pattern. Therefore, the battery diagnostic device 100 has the advantage of being able to quickly diagnose the battery state during charging, as well as being able to specifically subdivide and diagnose the battery state.

[0079] Another embodiment in which the processor 120 determines a resistance change pattern will be described in detail below with reference to Fig. 5. Please note that for convenience of explanation, the details of the processor 120 diagnosing the battery state based on the determined resistance change pattern overlap with the details described above, and therefore will be briefly described or omitted.

[0080] FIG. 5 is a graph illustrating an example of how the processor 120 uses the resistance profile to determine a resistance change pattern according to various embodiments of the present invention.

[0081] Referring to FIG. 5, there is shown the reference profile Rr for the reference battery and the resistance profile Rd generated by the processor 120 as described in FIG.

[0082] The processor 120 can determine that the resistance change pattern is the first resistance change pattern if a first slope based on a first point r11 corresponding to the point tf at which charging ends on the resistance profile Rd and a second point r12 different from the first point r11 is less than a second slope based on a third point r13 on the reference profile Rr corresponding to the first point and a fourth point r14 on the reference profile Rr corresponding to the second point r12.

[0083] Specifically, the processor 120 may generate a first straight line Rdb based on a first point r11 and a second point r12 on the resistance profile Rd. For example, the first straight line Rdb may be a straight line including the first point r11 and the second point r12. That is, the first straight line Rdb may be a straight line connecting the first point r11 and the second point r12.

[0084] The processor 120 may generate a second straight line Rrb based on the third point r13 and the fourth point r14 on the reference profile Rr. For example, the second straight line Rrb may be a straight line including the third point r13 and the fourth point r14. That is, the second straight line Rrb may be a straight line connecting the third point r13 and the fourth point r14.

[0085] Here, the first point r11 and the third point r13 may correspond to the same point at the same time. Specifically, the correspondence between the first point r11 and the third point r13 may mean that the first point r11 corresponds to the resistance value of the battery to be diagnosed at the time tf when charging ends on the resistance profile Rd, and the third point r13 corresponds to the resistance value of the reference battery at the time tf when charging ends.

[0086] Furthermore, the second point r12 and the fourth point r14 may correspond to the same SOC. Specifically, the correspondence between the second point r12 and the fourth point r14 may mean that the second point r12 corresponds to the resistance value of the battery to be diagnosed corresponding to a predetermined SOC, and the fourth point r14 corresponds to the resistance value of the reference battery corresponding to the predetermined SOC. An embodiment in which the second point r12 and the fourth point r14 are determined will be described later with reference to FIGS. 6 and 7.

[0087] Referring to FIG. 5, a first line Rdb and a second line Rrb are shown. If the first slope of the first line Rdb is less than the second slope of the second line Rrb, the processor 120 may determine the resistance change pattern as a first resistance change pattern. Here, the first resistance change pattern may be a pattern in which the resistance value decreases. In various embodiments, if the difference between the first slope of the first line Rdb and the second slope of the second line Rrb exceeds a predetermined range, the processor 120 may determine the resistance change pattern as the first resistance change pattern. The processor 120 may diagnose a battery determined to have the first resistance change pattern as a defective battery. That is, the processor 120 may diagnose a battery determined to have the first resistance change pattern as an abnormal battery in which an overhang occurs equal to or exceeds a reference ratio.

[0088] If the first slope is greater than or equal to the second slope, the processor 120 can determine the resistance change pattern as the second resistance change pattern.

[0089] For example, if the first slope of the first straight line Rdb is equal to or greater than the second slope of the second straight line Rrb, the processor 120 can determine the resistance change pattern as the second resistance change pattern.

[0090] As another example, if the difference between the first slope of the first straight line Rdb and the second slope of the second straight line Rrb is less than a threshold, the processor 120 may determine the resistance change pattern to be the second resistance change pattern.

[0091] In addition, processor 120 may diagnose a battery determined to have the second resistance change pattern as a normal battery. That is, processor 120 may diagnose a battery determined to have the second resistance change pattern as a normal battery in which no overhang occurs. Alternatively, processor 120 may diagnose a battery determined to have the second resistance change pattern as a normal battery in which overhang occurs below a reference ratio.

[0092] The battery diagnostic device 100 according to an embodiment of the present invention can easily diagnose the battery state using not only the instantaneous slope at the end of charging but also the average slope at the end of charging and a predetermined point. That is, the battery diagnostic device 100 has the advantage of being able to more accurately diagnose the battery state by considering the change in the resistance of the battery at various points (especially at various times).

[0093] The following describes an embodiment in which the processor 120 determines the second point r12 and the fourth point r14.

[0094] The processor 120 may generate an SOC-resistance profile indicating the correspondence between the SOC (state of charge) and resistance value of the battery during the charging process of the battery. The processor 120 may also acquire a reference SOC-resistance profile indicating the correspondence between the SOC and resistance value of the reference battery during the charging process of the reference battery. Here, the reference SOC-resistance profile may be a profile indicating the correspondence between the resistance value and SOC extracted in advance through the charging process of the reference battery. The reference SOC-resistance profile may be pre-stored in the memory 130. In other words, the above-described reference profile is also a profile acquired during the charging process of the reference battery, and the reference profile may correspond to the reference SOC-resistance profile.

[0095] FIG. 6 is a graph showing an example of an SOC-resistance profile SOCd and a reference SOC-resistance profile SOCr according to one embodiment of the present invention.

[0096] 6, the x-axis of the graph represents SOC, and the y-axis represents resistance. Here, the x-axis is expressed in percent (%), but it can also be expressed as a number between 0 and 1.

[0097] The processor 120 may calculate the SOC of the battery at predetermined intervals during the charging process of the battery, and generate an SOC-resistance profile SOCd by mapping the calculated SOC with the resistance value of the battery measured in the above manner. Figure 6 shows the SOC-resistance profile SOCd generated by the processor 120 and a reference SOC-resistance profile SOCr pre-stored in the memory 130.

[0098] The processor 120 can determine a target resistance value Rt corresponding to a predetermined SOC in the generated SOC-resistance profile SOCd. For example, the predetermined SOC can correspond to approximately 60%, but is not limited to such a value. The process by which the processor 120 determines the predetermined SOC will be described in more detail below with reference to FIG. 7.

[0099] The processor 120 may determine a point on the resistance profile corresponding to the target resistance value Rt as the second point r12. Specifically, the processor 120 may determine the target resistance value Rt corresponding to a predetermined SOC, and may determine a point on the resistance profile Rd corresponding to the target resistance value Rt as the second point r12, as described with reference to Fig. 5. That is, the processor 120 may determine a point on the resistance profile Rd where the battery has the target resistance value Rt corresponding to a predetermined SOC (e.g., 60%) as the second point r12 for calculating the average slope.

[0100] Meanwhile, the processor 120 can use the reference SOC-resistance profile to determine the fourth point r14 of the second straight line Rrb for determining the average slope.

[0101] The processor 120 may determine a reference resistance value corresponding to a predetermined SOC in a reference SOC-resistance profile corresponding to the reference profile. Specifically, the processor 120 may determine a reference resistance value Rf corresponding to the same SOC as the SOC used to determine the target resistance value Rt in the reference SOC-resistance profile. Here, in order to select a comparison target, it is preferable to determine the target resistance value Rt and the reference resistance value Rf at the same SOC.

[0102] The processor 120 may determine a point on the reference profile corresponding to a reference resistance value as the fourth point r14. Specifically, the processor 120 may determine a reference resistance value Rf corresponding to a predetermined SOC, and as described with reference to FIG. 5, may determine a point on the reference profile Rr corresponding to the reference resistance value Rf as the fourth point r14 for calculating the average slope. In this manner, the processor 120 may use points on the resistance profile Rd and the reference profile Rr corresponding to the end of charging and points where the state of charge of the battery reaches the predetermined SOC to determine the resistance change pattern. In addition, the processor 120 may use a differential profile when determining the predetermined SOC used to determine the resistance change pattern. A detailed embodiment will be described below with reference to FIG. 7.

[0103] FIG. 7 is an example of a differential profile showing the correspondence between differential voltage and SOC based on the SOC and voltage of a battery.

[0104] The processor 120 can be configured to generate a derivative profile that indicates the correspondence between the derivative voltage and the SOC.

[0105] Here, the differential voltage is the value obtained by differentiating the battery voltage with respect to the SOC, and can be expressed as dV / dSOC. That is, the differential voltage can correspond to a value that indicates the instantaneous rate of change of the voltage with respect to the SOC.

[0106] The differential profile may be represented as an XY graph with the SOC on the X axis and the differential voltage value on the Y axis. The differential profile may include multiple peaks P1, P2, P3, and P4. For example, the processor 120 may detect a first peak P1, a second peak P2, a third peak P3, and a fourth peak P4. Here, the peaks may be points on the differential profile that have an upwardly convex shape.

[0107] The processor 120 may determine peaks that belong to a predetermined SOC interval in the differential profile corresponding to the SOC of the battery and the voltage value of the battery.

[0108] Referring to FIG. 7, for example, the processor 120 may determine the interval between the first SOC (SOC1) and the second SOC (SOC2) as a predetermined SOC interval and determine peaks belonging to the interval. For example, the first SOC (SOC1) may be 50% and the second SOC (SOC2) may be 70%. In this case, the predetermined SOC interval is the interval between 50% and 70%, but is not limited to these values. Referring to FIG. 7, the processor 120 may determine the third peak P3 as a peak for determining the target resistance value Rt and the reference resistance value Rf. That is, the third peak P3 may be determined as a target peak for determining the target resistance value Rt and the reference resistance value Rf. In various embodiments, when the processor 120 determines the interval between the first SOC (SOC1) and the third SOC (SOC3) as a predetermined SOC interval, the third peak P3 and the fourth peak P4 may belong to the interval. In this case, the processor 120 may determine the third peak P3, which has a relatively large differential voltage value (dV / dSOC), as the peak for determining the target resistance value Rt and the reference resistance value Rf. Alternatively, the processor 120 may determine the peak with the largest differential voltage value (e.g., the third peak P3) among the peaks in the entire section of the differential profile as the peak for determining the target resistance value Rt and the reference resistance value Rf.

[0109] The processor 120 may determine the SOC corresponding to the determined peak as the predetermined SOC. For example, referring to FIG. 7, the processor 120 may determine the third peak P3 as the peak for determining the target resistance value Rt and the reference resistance value Rf. The processor 120 may determine the SOC corresponding to the third peak P3 as the predetermined SOC. For example, the determined predetermined SOC may be 60%. The processor 120 may determine the target resistance value Rt and the reference resistance value Rf corresponding to the predetermined SOC determined using the SOC-resistance profile SOCd and the reference SOC-resistance profile SOCr, as described with reference to FIG. 6. Specifically, the processor 120 may determine the resistance value at a point on the SOC-resistance profile SOCd where the SOC is 60% as the target resistance value Rt. The processor 120 may also determine the resistance value at a point on the reference SOC-resistance profile SOCr where the SOC is 60% as the reference resistance value Rf.

[0110] The processor 120 may determine a second point r12 on the resistance profile Rd that corresponds to the determined target resistance value Rt, as described with reference to Figure 5. Similarly, the processor 120 may determine a fourth point r14 on the reference profile Rr that corresponds to the determined reference resistance value Rf.

[0111] According to this embodiment of the present invention, the processor 120 can detect changes in resistance that are periodically calculated during the battery charging process and determine a resistance change pattern, and can easily determine the battery state based on the determined resistance change pattern.

[0112] The battery diagnostic device 100 according to the present invention can be applied to a BMS. That is, a BMS according to the present invention can include the above-described battery diagnostic device 100. In this configuration, at least some of the components of the battery diagnostic device 100 can be realized by complementing or adding functions of components included in a conventional BMS. For example, the measurement unit 110, processor 120, and memory 130 of the battery diagnostic device 100 can be realized as components of a BMS.

[0113] FIG. 8 exemplarily illustrates a battery pack 10 including a battery diagnostic device 100 according to the present invention. Referring to FIG. 8, the battery diagnostic device 100 according to the present invention may be provided in the battery pack 10. That is, the battery pack 10 according to the present invention may include the above-described battery diagnostic device 100 according to the present invention and one or more battery cells B. The battery pack 10 according to the present invention may further include components typically included in a battery pack 10, such as one or more secondary batteries, a Battery Management System (BMS), a current sensor, a relay, a fuse, a pack case, etc., in addition to the battery diagnostic device 100 according to the present invention. At least some of the components of the battery diagnostic device 100 according to the present invention may be implemented using conventional components included in the battery pack 10. For example, the measurement unit 110 of the battery diagnostic device 100 according to the present invention may be implemented using a voltage sensor included in the battery pack 10. At least some functions and operations of the processor 120 of the battery diagnostic device 100 according to the present invention may be implemented using a BMS included in the battery pack 10.

[0114] FIG. 9 exemplarily illustrates an automobile 1 including a battery diagnostic device 100 according to the present invention. Referring to FIG. 9, the battery diagnostic device 100 according to the present invention can be applied to the automobile 1. That is, the automobile 1 according to the present invention can include the above-described battery diagnostic device 100 according to the present invention. In particular, in the case of an electric vehicle, the battery pack 10 is a very important component as a driving source, and therefore the battery diagnostic device 100 according to the present invention can be more effectively applied. Furthermore, the automobile 1 according to the present invention can further include various other devices, such as a vehicle body, a vehicle control unit such as an ECU (Electronic Control Unit), a motor, connection terminals, a DC-DC converter, etc., in addition to the battery diagnostic device 100. Needless to say, the automobile 1 according to the present invention can also employ components typically included in automobiles.

[0115] 10 is a flow chart showing a battery diagnostic method according to an embodiment of the present invention. In FIG. 8, each step may be performed by a component of the battery diagnostic device 100 according to the present invention.

[0116] Referring to FIG. 10, the battery diagnosis method according to the present invention may include a voltage value measuring step (S110), a resistance value calculating step (S120), a resistance change pattern determining step (S130), and a battery state determining step (S140).

[0117] Step S110 is a step of measuring the voltage value of the battery while the battery is being charged, and can be performed by the measurement unit 110.

[0118] Specifically, the measurement unit 110 can measure the voltage value of the battery at predetermined intervals.

[0119] For example, in the embodiment of FIG. 2, the processor 120 applies a charging current to the battery in the form of pulses at predetermined intervals, and the measurement unit 110 can measure the voltage value of the battery while the pulse signal is being applied to the battery.

[0120] Step S120 is a step of calculating the resistance value of the battery based on the voltage value of the battery measured in step S110, and can be performed by the processor 120.

[0121] For example, the processor 120 can calculate the resistance value based on the change in the voltage value relative to the amount of charging current corresponding to the pulse signal at each predetermined period.

[0122] Step S130 is a step of comparing the plurality of resistance values ​​calculated in step S120 with a preset reference profile to determine a resistance change pattern, and can be performed by the processor 120.

[0123] Specifically, the processor 120 can determine the resistance change pattern as the first resistance change pattern or the second resistance change pattern based on the result of comparing the plurality of resistance values ​​with the reference profile.

[0124] For example, the processor 120 may compare a first slope in a resistance profile indicating changes in a plurality of resistance values ​​with a second slope in a reference profile, and determine a resistance change pattern according to the comparison result.

[0125] Step S140 is a step of determining the state of the battery based on the resistance change pattern determined in step S130, and can be performed by the processor 120.

[0126] For example, if the resistance change pattern is determined to be the first resistance change pattern, the processor 120 may determine that the battery state is a defective state. Conversely, if the resistance change pattern is determined to be the second resistance change pattern, the processor 120 may determine that the battery state is a normal state.

[0127] The steps S110 to S140 can be applied in the same or similar manner to the battery diagnostic device 100 according to the present invention, and therefore, a detailed description of each step of the battery control method according to the present invention will be omitted.

[0128] The embodiments of the present invention described above are not realized through devices and methods, but can also be realized through a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded, and such a program or recording medium can be easily realized by anyone skilled in the technical field to which the present invention belongs based on the description of the above embodiments.

[0129] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that a person having ordinary knowledge in the technical field to which the present invention pertains can make various modifications and variations within the technical spirit of the present invention and the equivalent scope of the following claims.

[0130] Furthermore, the present invention described above is not limited to the above-described embodiments and the attached drawings, and various substitutions, modifications, and alterations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains, without departing from the technical concept of the present invention. Therefore, the present invention can be configured by combining all or part of each embodiment as necessary to make various modifications. [Explanation of symbols]

[0131] 100: Battery diagnostic device 110: Measuring part 120: Processor 130: Memory

Claims

1. a measuring unit configured to measure a voltage value of the battery at predetermined intervals during charging of the battery; a processor configured to calculate a resistance value of the battery based on a measured voltage value of the battery, compare the calculated resistance values ​​with a preset reference profile, and determine a resistance change pattern as a first or second resistance change pattern, and determine a state of the battery as a normal state or a fault state in which an overhang has occurred based on the determined resistance change pattern.

2. The reference profile may include:

2. The battery diagnostic device according to claim 1, wherein the profile indicates a change in a plurality of resistance values ​​calculated during the charging of the reference battery for each predetermined period.

3. The processor:

2. The battery diagnostic device according to claim 1, wherein the battery diagnostic device is configured to calculate a first slope in a resistance profile, calculate a second slope in the reference profile, and determine the resistance change pattern based on a result of comparing the first slope with the second slope.

4. The processor: determining the resistance change pattern as the first resistance change pattern when a first slope at the end of charging on the resistance profile is less than a second slope at the end of charging on the reference profile; 4. The battery diagnostic device according to claim 3, wherein the battery diagnostic device is configured to determine the resistance change pattern as the second resistance change pattern when the first gradient is equal to or greater than the second gradient.

5. The processor: determining the resistance change pattern as the first resistance change pattern when a first slope based on a first point corresponding to the end of charge on the resistance profile and a second point different from the first point on the resistance profile is less than a second slope based on a third point corresponding to the first point on the reference profile and a fourth point corresponding to the second point on the reference profile; 4. The battery diagnostic device according to claim 3, wherein the battery diagnostic device is configured to determine the resistance change pattern as the second resistance change pattern when the first gradient is equal to or greater than the second gradient.

6. The processor:

6. The battery diagnostic device of claim 5, further comprising: generating an SOC-resistance profile indicating a correspondence relationship between an SOC of the battery and the calculated resistance value while the battery is being charged; determining a target resistance value corresponding to a predetermined SOC from the SOC-resistance profile; and determining a point in the resistance profile corresponding to the target resistance value as the second point.

7. The processor:

7. The battery diagnostic device of claim 6, further comprising: determining a reference resistance value corresponding to the predetermined SOC from a reference SOC-resistance profile corresponding to the reference profile; and determining a point in the reference profile corresponding to the reference resistance value as the fourth point.

8. The processor:

7. The battery diagnostic device according to claim 6, further comprising: determining a peak belonging to a predetermined SOC range in a differential profile corresponding to the SOC of the battery and the voltage value of the battery; and determining an SOC corresponding to the determined peak as the predetermined SOC.

9. The processor: If the resistance change pattern is the first resistance change pattern, the battery is determined to be in a defective state; 2. The battery diagnostic device according to claim 1, wherein the battery is determined to be in a normal state when the resistance change pattern is the second resistance change pattern.

10. The processor:

2. The battery diagnostic device according to claim 1, wherein the battery is charged by repeatedly changing a charging current value of the battery at predetermined intervals, and the resistance value is calculated based on a change in voltage value while the charging current value of the battery corresponds to the predetermined value.

11. A battery pack comprising the battery diagnostic device according to any one of claims 1, 2 and 4-10.

12. A vehicle comprising the battery diagnostic device according to any one of claims 1, 2 and 4-10.

13. a voltage value measuring step of measuring a voltage value of the battery at predetermined intervals during charging of the battery; a resistance value calculation step of calculating a resistance value of the battery based on the measured voltage value of the battery; a resistance change pattern determination step of comparing the calculated resistance values ​​with a preset reference profile to determine the resistance change pattern as a first resistance change pattern or a second resistance change pattern; and a battery state determining step of determining the state of the battery as a normal state or a defective state in which an overhang has occurred based on the determined resistance change pattern.

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