Battery condition diagnostic device and method

Abstract

A battery state diagnosis device according to an embodiment of the present invention includes a voltage measurement unit configured to measure a voltage of a battery and, if the measured voltage reaches a preset first reference voltage, measure a target voltage for the battery; a resistance measurement unit configured to measure a target resistance of the battery if the measured voltage reaches a preset second reference voltage; and a control unit configured to determine a voltage increase / decrease pattern with respect to the target voltage based on a voltage profile in which the target voltage is stored, determine a resistance increase / decrease pattern with respect to the target resistance based on a resistance profile in which the target resistance is stored, and diagnose the state of the battery from the voltage increase / decrease pattern and the resistance increase / decrease pattern according to a preset diagnosis rule.

Description

Technical Field

[0001] This application claims priority based on Korean Patent Application No. 10-2022-0119253 filed on September 21, 2022, and Korean Patent Application No. 10-2023-0126116 filed on September 21, 2023, and all the contents disclosed in the specifications and drawings of those applications are incorporated into this application.

[0002] The present invention relates to a battery state diagnosis device and method, and more particularly, to a battery state diagnosis device and method capable of diagnosing the state of a battery.

Background Art

[0003] In recent years, with the rapid growth in demand for portable electronic products such as notebook computers, video cameras, and mobile phones, and the full-scale development of electric vehicles, energy storage batteries, robots, artificial satellites, etc., research on high-performance rechargeable batteries has been actively conducted.

[0004] Currently commercialized batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc. Among them, lithium batteries are in the spotlight because they can be charged and discharged freely with almost no memory effect compared to nickel-based batteries, have a very low self-discharge rate, and a high energy density.

[0005] Regarding such batteries, much research has been conducted in terms of increasing capacity and density, but the aspects of improving lifespan and safety are also important.

[0006] For example, it is necessary to prevent the phenomenon of lithium deposition on the surface of the negative electrode (lithium plating, Li-plating). When lithium is deposited on the surface of the negative electrode, it can cause side reactions with the electrolyte and changes in the battery's kinetic balance, leading to battery degradation. In addition, the deposition of lithium metal on the surface of the negative electrode can cause an internal short circuit in the battery, posing a risk of fire and explosion due to the short circuit.

[0007] Other examples include electrolyte side reactions and cathode degradation, in addition to lithium deposition, which can also affect battery life and stability.

[0008] Therefore, there is a need for technology that can improve battery life and stability by accurately and quickly diagnosing the current state of the battery. [Overview of the project] [Problems that the invention aims to solve]

[0009] This invention was devised to solve the above-mentioned problems, and aims to provide a battery condition diagnostic device and method that can quickly and accurately diagnose the state of a battery.

[0010] Other objects and advantages of the present invention can be understood from the following description and will be more clearly shown by the embodiments of the present invention. Furthermore, the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. [Means for solving the problem]

[0011] A battery state diagnostic device according to one aspect of the present invention includes: a voltage measuring unit configured to measure the voltage of a battery and, if the measured voltage reaches a preset first reference voltage, to measure a target voltage for the battery; a resistance measuring unit configured to measure the target resistance of the battery when the measured voltage reaches a preset second reference voltage; and a control unit configured to determine a voltage increase / decrease pattern for the target voltage based on a stored voltage profile, determine a resistance increase / decrease pattern for the target resistance based on a stored resistance profile, and diagnose the state of the battery from the voltage increase / decrease pattern and the resistance increase / decrease pattern according to a preset diagnostic rule.

[0012] The control unit can determine the voltage increase / decrease pattern as a first voltage pattern or a second voltage pattern, determine the resistance increase / decrease pattern as a first resistance pattern or a second resistance pattern, and diagnose the state of the battery differently depending on the combination of the voltage increase / decrease pattern and the resistance increase / decrease pattern.

[0013] The control unit may be configured to diagnose the state of the battery as an electrolyte side reaction state, lithium deposition state, positive electrode degradation state, or negative electrode stabilization state.

[0014] The control unit may be configured to diagnose the state of the battery as the electrolyte side reaction state when it is determined that the voltage increase / decrease pattern is the first voltage pattern and the resistance increase / decrease pattern is the first resistance pattern.

[0015] The control unit may be configured to diagnose the state of the battery as the lithium deposition state when it is determined that the voltage increase / decrease pattern is the first voltage pattern and the resistance increase / decrease pattern is the second resistance pattern.

[0016] The control unit may be configured to diagnose the state of the battery as the positive electrode degradation state when it is determined that the voltage increase / decrease pattern is the second voltage pattern and the resistance increase / decrease pattern is the first resistance pattern.

[0017] The control unit may be configured to diagnose the state of the battery as the negative electrode stabilized state when it is determined that the voltage increase / decrease pattern is the second voltage pattern and the resistance increase / decrease pattern is the second resistance pattern.

[0018] The control unit may be configured to set the operating conditions of the battery in accordance with the diagnostic results for the state of the battery.

[0019] The control unit may be configured to reduce at least one of the battery temperature and the upper limit of SOC when the state of the battery is diagnosed as being in the electrolyte side reaction state or the positive electrode degradation state.

[0020] The control unit may be configured to reduce the upper limit of the battery's charge / discharge C rate when the battery's state is diagnosed as the lithium deposition state.

[0021] The control unit may be configured to diagnose the state of the battery each time the voltage profile and the resistance profile are updated.

[0022] The resistance measuring unit may be configured to measure the target resistance based on the amount of voltage change of the battery over a predetermined period of time once the measured voltage reaches the second reference voltage.

[0023] The first reference voltage may be the discharge termination voltage set for the battery.

[0024] The second reference voltage may be a voltage belonging to a preset negative electrode flat section within the usable voltage range of the battery.

[0025] A battery pack according to another aspect of the present invention includes a battery state diagnosis device according to an aspect of the present invention.

[0026] A battery state diagnosis method according to still another aspect of the present invention includes a voltage measurement step of measuring the voltage of a battery, a target measurement step of measuring a target voltage for the battery if the measured voltage reaches a preset first reference voltage, and measuring a target resistance of the battery if the measured voltage reaches a preset second reference voltage, a pattern determination step of determining a voltage increase / decrease pattern for the target voltage based on a voltage profile in which the target voltage is stored, and determining a resistance increase / decrease pattern for the target resistance based on a resistance profile in which the target resistance is stored, and a battery state diagnosis step of diagnosing the state of the battery from the voltage increase / decrease pattern and the resistance increase / decrease pattern according to a preset diagnosis rule.

Advantages of the Invention

[0027] According to an aspect of the present invention, the state of a battery can be diagnosed in detail by classifying it according to the combination of the voltage increase / decrease pattern and the resistance increase / decrease pattern of the battery.

[0028] Also, according to an aspect of the present invention, since the state of a battery is diagnosed based on voltage and resistance, the current state of the battery can be diagnosed quickly.

[0029] [[ID=IP=19]] The effects of the present invention are not limited to the effects described above, and other effects of the present invention not mentioned will be clearly understood by those skilled in the art from the description of the claims section.

[0030] The following drawings attached to this specification serve to further understand the technical idea of the present invention together with the detailed description of the invention to be described later, and the present invention is not construed as being limited only to the matters described in the drawings.

Brief Description of the Drawings

[0031] [Figure 1] This diagram schematically shows a battery status diagnostic device according to one embodiment of the present invention. [Figure 2] This figure schematically shows one embodiment of the negative electrode resistance profile. [Figure 3] This figure schematically illustrates one embodiment of a battery profile. [Figure 4] This figure schematically illustrates one embodiment of a differential profile. [Figure 5] This diagram schematically shows a set diagnostic rule used by a battery status diagnostic device according to one embodiment of the present invention. [Figure 6] This figure schematically shows the first voltage profile for the first battery according to one embodiment of the present invention. [Figure 7] This figure schematically shows the first resistance profile for the first battery according to one embodiment of the present invention. [Figure 8] This figure schematically shows the second voltage profile for the second battery according to one embodiment of the present invention. [Figure 9] This figure schematically shows the second resistance profile for the second battery according to one embodiment of the present invention. [Figure 10] This figure schematically illustrates an exemplary configuration of a battery pack according to another embodiment of the present invention. [Figure 11] This figure schematically illustrates an exemplary configuration of an electric vehicle according to yet another embodiment of the present invention. [Figure 12] This figure schematically illustrates an exemplary configuration of an energy storage device according to yet another embodiment of the present invention. [Figure 13] This figure schematically illustrates a battery condition diagnosis method according to yet another embodiment of the present invention. [Modes for carrying out the invention]

[0032] Terms and words used in this specification and in the claims are not to be interpreted in their ordinary and dictionary sense, but rather in a sense and concept that corresponds to the technical idea of ​​the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best describe their invention.

[0033] Therefore, the embodiments described herein and the configurations shown in the drawings represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the present invention. It should be understood that there are various equivalents and modifications that can be substituted for these embodiments at the time of filing this application.

[0034] Furthermore, in describing the present invention, if it is determined that a specific description of a related known configuration or function would obscure the gist of the present invention, such detailed description will be omitted.

[0035] Terms that include ordinal numbers, such as "1st," "2nd," etc., are used to distinguish one of several components from others, and these terms do not limit the components themselves.

[0036] When a part of the specification "includes" a certain component, unless otherwise specified, this does not exclude other components, but rather means that it may include other components.

[0037] Furthermore, when a part of the specification is described as being "connected" to another part, this includes not only "direct connections" but also "indirect connections" mediated by other elements.

[0038] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0039] Figure 1 is a schematic diagram showing a battery status diagnostic device 100 according to one embodiment of the present invention.

[0040] Referring to Figure 1, the battery condition diagnostic device 100 includes a voltage measuring unit 110, a resistance measuring unit 120, and a control unit 130.

[0041] Here, "battery" refers to a single, independent cell that has a negative terminal and a positive terminal and is physically separable. For example, a lithium-ion battery or a lithium-polymer battery can be considered a battery. Alternatively, "battery" may also refer to a battery module in which multiple cells are connected in series and / or parallel. For the sake of explanation, in the following, "battery" will be used to refer to a single, independent cell.

[0042] The voltage measuring unit 110 may be configured to measure the voltage of the battery.

[0043] Specifically, the voltage measuring unit 110 can be electrically connected to the positive and negative terminals of the battery. Furthermore, the voltage measuring unit 110 can measure the positive and negative potentials of the battery, calculate the difference between the positive and negative potentials, and measure the terminal voltage of the battery.

[0044] The voltage measurement unit 110 may be configured to measure a target voltage for the battery once the measured voltage reaches a preset first reference voltage.

[0045] Here, the first reference voltage may be the discharge termination voltage set for the battery. For example, the first reference voltage may be the discharge termination voltage set to reflect the current state of the battery, and may be the lower limit voltage for the battery. That is, the first reference voltage for one battery may be set to 2.8V, and the first reference voltage for another battery may be set to 3.2V.

[0046] Specifically, the voltage measuring unit 110 can measure the target voltage of the battery each time the battery voltage reaches a first reference voltage set for the battery. Preferably, the target voltage may be the open circuit voltage (OCV).

[0047] For example, once the battery voltage reaches the first reference voltage, the battery may enter an idle state for approximately 10 minutes. That is, once the battery has discharged to the first reference voltage, it may enter an unloaded state for a certain period of time. The voltage measurement unit 110 can measure the target voltage of the battery after the battery state has stabilized (i.e., after an unloaded state has been maintained for a certain period of time).

[0048] The resistance measuring unit 120 may be configured to measure the target resistance of the battery when the measured voltage reaches a preset second reference voltage.

[0049] Here, the second reference voltage may be a voltage belonging to a predetermined negative-electrode flat section within the battery's usable voltage range. Specifically, the second reference voltage may be any single voltage belonging to the negative-electrode flat section within the battery's usable voltage range. For example, the second reference voltage may represent the voltage value with the smallest corresponding resistance in the negative-electrode flat section. As another example, the second reference voltage may represent the smallest voltage value in the negative-electrode flat section. In other words, the second reference voltage can be applied without restriction as long as it is a voltage value belonging to the negative-electrode flat section.

[0050] Specifically, the negative electrode flat section refers to the voltage range in which the negative electrode resistance does not change significantly even when the negative electrode voltage increases. The negative electrode flat section will be specifically defined below with reference to the first to third embodiments.

[0051] Figure 2 is a schematic diagram illustrating one embodiment of the negative electrode resistance profile NP. Specifically, the negative electrode resistance profile NP in Figure 2 is a profile showing the correspondence between voltage and resistance for the negative electrode of a battery. Preferably, the negative electrode resistance profile NP may be a profile obtained for a reference battery corresponding to the battery. Here, the reference battery means a battery in the BOL (Beginning of Life) state, or a reference battery manufactured to correspond to a battery in the BOL state. For example, in the embodiment of Figure 2, the usable voltage range of the battery may be Vi[V]~Vf[V]. The first resistance value R1 corresponding to L[V] among the voltages belonging to the usable voltage range (Vi~Vf) may be the minimum resistance.

[0052] In the first embodiment, the negative electrode flat section RR can be defined as a voltage section in which the rate of change of the negative electrode resistance with respect to the negative electrode voltage is greater than or equal to a reference value. In the embodiment shown in Figure 2, since the resistance decreases as the voltage of the negative electrode increases, the rate of change of the resistance with respect to voltage can be calculated as a negative number in the voltage section from Vi[V] to L[V]. Also, in the voltage section from L[V] to Vf[V], the rate of change of the resistance with respect to voltage can be calculated as a positive number. Specifically, the slope (instantaneous rate of change of resistance with respect to voltage) at the point corresponding to K[V] can be greater than or equal to a preset reference value. Furthermore, the slope can be maintained above the reference value even in high voltage sections above K[V]. That is, in the voltage section from K[V] to Vf[V], the slope can be maintained above the reference value. Therefore, the voltage section from K[V] to Vf[V] in which the rate of change of the resistance with respect to voltage is greater than or equal to a reference value can correspond to the negative electrode flat section RR.

[0053] In the second embodiment, the negative electrode flat section RR can be defined as the voltage section corresponding to the resistance section within the critical resistance range from the minimum resistance of the negative electrode resistance profile NP. In the embodiment shown in Figure 2, the minimum resistance of the negative electrode resistance profile NP is the first resistance value R1. Therefore, the voltage section K to Vf corresponding to the resistance sections R1 to R2 within the critical resistance range TH from the first resistance value R1 may correspond to the negative electrode flat section RR.

[0054] For example, the critical resistance TH can be set as the resistance difference between the minimum resistance (first resistance value R1) of the negative electrode resistance profile NP and the resistance corresponding to the maximum voltage Vf. In the embodiment shown in Figure 2, since the resistance value corresponding to the voltage Vf[V] is the second resistance value R2, the critical resistance TH can be set as the resistance difference between the first resistance value R1 and the second resistance value R2. Furthermore, the voltage interval K to Vf corresponding to the resistance interval R1 to R2 belonging to the critical resistance TH from the first resistance value R1 may correspond to the negative electrode flat interval RR.

[0055] In the third embodiment, the negative electrode flat section RR may be defined based on the battery profile and differential profile for the battery.

[0056] Figure 3 is a schematic diagram illustrating one embodiment of the battery profile PF. Specifically, in the embodiment shown in Figure 3, the battery profile PF is a profile that shows the correspondence between the SOC (State of Charge) and voltage of a reference battery. The positive electrode profile PP is a profile that shows the correspondence between the SOC and voltage of the positive electrode of the reference battery, and the negative electrode profile PN is a profile that shows the correspondence between the SOC and voltage of the negative electrode of the reference battery.

[0057] Figure 4 is a schematic diagram illustrating one embodiment of the differential profile DP. Specifically, in the embodiment shown in Figure 4, the differential profile is a profile showing the correspondence between the SOC of a reference battery and the differential voltage. Here, the differential voltage is the value obtained by differentiating the voltage with respect to SOC, and can be expressed as "dV / dSOC".

[0058] In the embodiment shown in Figure 4, the SOC corresponding to the lowest differential voltage in the differential profile is L[%]. The target peak TP is included in the SOC interval greater than or equal to L[%], and the SOC corresponding to the target peak TP is T[%]. For example, in the SOC interval greater than or equal to L[%], the peak with the lowest corresponding SOC can be determined to be the target peak TP. In other words, the target peak TP can be determined to be the first local maximum (where the SOC is T[%]) that appears after the local minimum (where the SOC is L[%]) corresponding to the lowest differential voltage in the differential profile.

[0059] Generally, the voltage range after the target peak TP is known to be a range where the positive electrode is the primary responder and the negative electrode participates less in the reaction. Therefore, the SOC corresponding to the target peak TP in the differential profile can be identified as T[%]. In the embodiment shown in Figure 3, the voltage corresponding to SOCT[%] in the battery profile PF is K[V]. That is, the voltage range from K[V] to Vf[V] is a voltage range where the positive electrode is the primary responder. Therefore, the voltage range from K[V] to Vf[V] can correspond to the negative electrode flat range RR.

[0060] Specifically, the resistance measuring unit 120 can measure the target resistance of the battery based on the amount of voltage change of the battery over a predetermined period of time once the measured voltage reaches the second reference voltage.

[0061] In one embodiment, the resistance measuring unit 120 can measure the discharge current over a predetermined period of time starting from the point when the measured voltage reaches the second reference voltage. The resistance measuring unit 120 can also calculate the voltage change based on the battery voltage measured by the voltage measuring unit 110 during the predetermined period of time.

[0062] For example, let's assume that the time when the measured voltage reaches the second reference voltage is t1, and a predetermined time interval is Δt. During the interval Δt from time t1, the voltage measurement unit 110 can measure the battery voltage, and the resistance measurement unit 120 can measure the discharge current. The resistance measurement unit 120 can also calculate the target resistance of the battery using the voltage change ΔV and the discharge current ΔI during the interval Δt. In other words, the resistance measurement unit 120 can calculate the target resistance using Ohm's law.

[0063] In another embodiment, the resistance measuring unit 120 may be configured to output a pulse signal to the battery for a predetermined period of time once the measured voltage reaches a second reference voltage.

[0064] Specifically, the resistance measuring unit 120 can be electrically connected to the positive and negative terminals of the battery. Furthermore, the resistance measuring unit 120 can output a pulse signal of a predetermined magnitude to the battery. For example, the resistance measuring unit 120 can output a pulse signal with a magnitude of T[mA] over 0.1 seconds in the direction of battery discharge. That is, the resistance measuring unit 120 can output a pulse signal to the negative terminal side of the battery.

[0065] Furthermore, the resistance measurement unit 120 may be configured to measure the target resistance based on the amount of change in the battery voltage while a pulse signal is applied.

[0066] When a pulse signal is applied in the direction of battery discharge, the battery voltage drops. That is, the voltage measurement unit 110 can measure the battery voltage during a predetermined time while the pulse signal is applied. The resistance measurement unit 120 can also calculate the voltage difference ΔV between the battery voltage and the second reference voltage at the time the pulse signal output ends. Here, the voltage difference ΔV can be calculated using the formula "second reference voltage - battery voltage".

[0067] Furthermore, the resistance measuring unit 120 can calculate the amount of current ΔI applied to the battery during a predetermined time. Here, the amount of current can be calculated using the formula "predetermined time × magnitude of current".

[0068] Furthermore, the resistance measuring unit 120 can measure the target resistance from the voltage difference ΔV and the current ΔI. Here, the target resistance can be calculated using the formula "voltage difference ÷ current".

[0069] The control unit 130 may be configured to determine a voltage increase / decrease pattern for the target voltage based on a voltage profile in which the target voltage is stored.

[0070] Specifically, the control unit 130 may be configured to determine the voltage increase / decrease pattern as a first voltage pattern or a second voltage pattern.

[0071] For example, the control unit 130 may select multiple target voltages from a voltage profile. Preferably, the control unit 130 may select multiple target voltages that have been most recently saved from among the multiple target voltages included in the voltage profile. The control unit 130 may also determine a voltage increase / decrease pattern for the battery by comparing the magnitudes of the selected multiple target voltages.

[0072] If the magnitude of the target voltage increases over time, the voltage increase / decrease pattern for the battery can be determined to be the first voltage pattern.

[0073] Conversely, if the magnitude of the target voltage decreases over time, the voltage increase / decrease pattern for the battery may be determined to be the second voltage pattern. Also, if the magnitude of the target voltage remains constant over time, that is, if the difference in magnitude between multiple target voltages is smaller than a predetermined critical value, the voltage increase / decrease pattern for the battery may also be determined to be the second voltage pattern.

[0074] The control unit 130 may be configured to determine a resistance increase / decrease pattern for the target resistance based on the resistance profile in which the target resistance is stored.

[0075] The control unit 130 may be configured to determine the resistance increase / decrease pattern as a first resistance pattern or a second resistance pattern.

[0076] For example, the control unit 130 may select multiple target resistors from a resistance profile. Preferably, the control unit 130 may select multiple target resistors that have been most recently saved from among the multiple target resistors included in the resistance profile. The control unit 130 may also determine a resistance increase / decrease pattern for the battery by comparing the magnitudes of the selected multiple target resistors.

[0077] If the magnitude of the target resistance increases over time, the resistance increase / decrease pattern for the battery can be determined to be the first resistance pattern.

[0078] Conversely, if the magnitude of the target resistance decreases over time, the resistance increase / decrease pattern for the battery can be determined to be the second resistance pattern. Also, if the magnitude of the target resistance remains constant over time, that is, if the difference in magnitude between multiple target resistances is smaller than a predetermined critical value, the resistance increase / decrease pattern for the battery can also be determined to be the second resistance pattern.

[0079] Preferably, the corresponding target voltage and target resistance can all be measured from a single discharge cycle of the battery. That is, in any one discharge cycle, the target resistance can be measured when the battery voltage reaches the second reference voltage, and the target voltage can be measured when the battery voltage reaches the first reference voltage. In other words, the multiple target voltages and multiple target resistances selected by the control unit 130 can be said to be multiple pairs of corresponding target voltages and target resistances that have been selected.

[0080] The control unit 130 may be configured to diagnose the battery status from voltage increase / decrease patterns and resistance increase / decrease patterns according to a preset diagnostic rule.

[0081] Specifically, the control unit 130 can diagnose the battery state differently depending on the combination of the voltage increase / decrease pattern and the resistance increase / decrease pattern. Preferably, the control unit 130 can be configured to diagnose the battery state as an electrolyte side reaction state, a lithium deposition state, a positive electrode degradation state, or a negative electrode stabilization state. That is, the control unit 130 can diagnose the battery state as an electrolyte side reaction state, a lithium deposition state, a positive electrode degradation state, or a negative electrode stabilization state depending on the combination of the voltage increase / decrease pattern and the resistance increase / decrease pattern.

[0082] Here, the electrolyte side reaction state refers to a state in which a side reaction occurs in the electrolyte (electrolyte solution), resulting in a decrease in battery performance. For example, an electrolyte side reaction refers to the reductive decomposition reaction of the electrolyte on the surface of the negative electrode. The lithium deposition state refers to a state in which lithium metal is deposited on the surface of the negative electrode of the battery. The positive electrode degradation state refers to a state in which the positive electrode has deteriorated due to a loss of positive electrode capacity. In other words, the electrolyte side reaction state, lithium deposition state, and positive electrode degradation state are abnormal states that may appear in a defective battery.

[0083] The negative electrode stabilization state refers to the state in which the negative electrode of a battery stabilizes. For example, the negative electrode stabilization state mainly appears in the initial cycle when a battery begins to be used, and it refers to the state in which the reaction area of ​​the negative electrode increases during the contraction and expansion process of the active material during initial charging and discharging. The negative electrode stabilization state can be a normal state that can occur in a healthy battery.

[0084] Figure 5 is a schematic diagram showing a set diagnostic rule used by a battery condition diagnostic device 100 according to one embodiment of the present invention.

[0085] The control unit 130 may be configured to diagnose the battery state as an electrolyte side reaction state when it is determined that the voltage increase / decrease pattern is a first voltage pattern and the resistance increase / decrease pattern is a first resistance pattern.

[0086] The control unit 130 may be configured to diagnose the state of the battery as a lithium deposition state when it is determined that the voltage increase / decrease pattern is a first voltage pattern and the resistance increase / decrease pattern is a second resistance pattern.

[0087] The control unit 130 may be configured to diagnose the battery state as a positive electrode degradation state when it is determined that the voltage increase / decrease pattern is a second voltage pattern and the resistance increase / decrease pattern is a first resistance pattern.

[0088] The control unit 130 may be configured to diagnose the battery state as a negative electrode stabilized state when it is determined that the voltage increase / decrease pattern is a second voltage pattern and the resistance increase / decrease pattern is a second resistance pattern.

[0089] A battery state diagnostic device 100 according to one embodiment of the present invention can diagnose the state of a battery in detail into four categories according to the combination of the battery's voltage increase / decrease pattern and resistance increase / decrease pattern. Since the battery state is diagnosed based on voltage and resistance, the current state of the battery can be diagnosed quickly. Therefore, according to the present invention, the current state of the battery can be diagnosed quickly and accurately.

[0090] On the other hand, the control unit 130 provided in the battery state diagnostic device 100 may selectively include a processor, ASIC (Application-Specific Integrated Circuit), other chipsets, logic circuits, registers, communication modems, data processing devices, etc., known in the industry, in order to execute the various control logics performed in the present invention. Furthermore, when the control logic is embodied as software, the control unit 130 may be embodied as a collection of program modules. In this case, the program modules are stored in memory and can be executed by the control unit 130. The memory may be provided inside or outside the control unit 130 and can be connected to the control unit 130 by various well-known means.

[0091] The battery status diagnostic device 100 may further include a recording unit 140. The recording unit 140 may store data and programs necessary for each component of the battery status diagnostic device 100 to operate and function, or data generated during the process of operation and functioning. The recording unit 140 is not particularly limited in type, as long as it is a known information recording means known to be able to record, erase, update, and read data. For example, information recording means may include RAM, flash memory, ROM, EEPROM, registers, etc. The recording unit 140 may also store program code that defines the processes that can be executed by each component of the battery status diagnostic device 100.

[0092] For example, voltage profiles, resistance profiles, and diagnostic rules may be stored in the recording unit 140. Target voltage measured by the voltage measurement unit 110 and target resistance measured by the resistance measurement unit 120 may also be stored in the recording unit 140. The control unit 130 can access the recording unit 140 to retrieve relevant information and diagnose the battery status based on the retrieved information.

[0093] Hereinafter, an embodiment of the first battery will be described with reference to Figures 6 and 7.

[0094] Figure 6 is a schematic diagram showing the first voltage profile VP1 for the first battery according to one embodiment of the present invention. Figure 7 is a schematic diagram showing the first resistance profile RP1 for the first battery according to one embodiment of the present invention. Referring to Figures 6 and 7, the target voltage and target resistance are measured for the first battery from the first cycle to the tenth cycle.

[0095] The control unit 130 may select multiple target voltages from the first voltage profile VP1. Specifically, the control unit 130 may select multiple target voltages considering when the target voltage was measured.

[0096] For example, suppose the control unit 130 selects two target voltages. The control unit 130 may first select the target voltage for the 10th cycle and the target voltage for the 9th cycle. That is, the priority of the target voltages selected by the control unit 130 may be higher the closer the time of measurement is to the present. Since the target voltage for the 10th cycle is greater than the target voltage for the 9th cycle, the control unit 130 may determine the voltage increase / decrease pattern of the first battery as the first voltage pattern.

[0097] Similarly, the control unit 130 may select multiple target resistors from the first resistance profile RP1. Specifically, the control unit 130 may select multiple target resistors taking into account when the target resistance was measured.

[0098] For example, suppose the control unit 130 selects two target resistors. The control unit 130 may first select the target resistor for the 10th cycle and the target resistor for the 9th cycle. That is, the priority of the target resistors selected by the control unit 130 may be higher the closer the measurement time is to the present. Since the target resistor for the 10th cycle is smaller than the target resistor for the 9th cycle, the control unit 130 may determine the resistance increase / decrease pattern of the first battery to be the second resistance pattern.

[0099] Since the voltage increase / decrease pattern for the first battery is determined to be the first voltage pattern and the resistance increase / decrease pattern is determined to be the second resistance pattern, the control unit 130 can diagnose the state of the first battery as a lithium deposition state.

[0100] Hereinafter, an embodiment of the second battery will be described with reference to Figures 8 and 9.

[0101] Figure 8 is a schematic diagram showing the second voltage profile VP2 for the second battery according to one embodiment of the present invention. Figure 9 is a schematic diagram showing the second resistance profile RP2 for the second battery according to one embodiment of the present invention. Referring to Figures 8 and 9, the target voltage and target resistance were measured for the second battery from the first cycle to the tenth cycle.

[0102] For example, suppose the control unit 130 selects three target voltages. The control unit 130 may select target voltages for the 8th to 10th cycles. Since the difference between the target voltage for the 8th cycle, the target voltage for the 9th cycle, and the target voltage for the 10th cycle is less than a predetermined critical value, the control unit 130 may determine the voltage increase / decrease pattern of the second battery to be the second voltage pattern.

[0103] Similarly, the control unit 130 may select three target resistors from the second resistance profile RP2. The three target resistors selected by the control unit 130 may correspond to the selected target voltage. That is, the control unit 130 may select target resistors for the 8th to 10th cycles. Since the target resistor for the 8th cycle is the smallest and the target resistor for the 10th cycle is the largest, the control unit 130 may determine the resistance increase / decrease pattern of the second battery to be the first resistance pattern.

[0104] Since the voltage increase / decrease pattern for the second battery is determined to be the second voltage pattern and the resistance increase / decrease pattern is determined to be the first resistance pattern, the control unit 130 can diagnose the state of the second battery as a positive electrode degradation state.

[0105] On the other hand, comparing the first voltage profile VP1 in Figure 6 with the second voltage profile VP2 in Figure 8, it can be seen that the first reference voltage set for the first battery and the first reference voltage set for the second battery are different. In other words, the battery condition diagnostic device 100 has the advantage of being able to diagnose the battery condition more accurately because it sets the first and second reference voltages to correspond to the condition of each battery.

[0106] The control unit 130 may be configured to set battery operating conditions in accordance with the diagnostic results for the battery status.

[0107] Specifically, the control unit 130 can set the battery's operating conditions to correspond to the battery condition diagnosis results in order to prevent or delay battery degradation. Here, the initial operating conditions for the battery may be set at the time of battery shipment. Generally, charge and discharge tests are performed during the battery manufacturing stage, and the initial operating conditions of the battery may be set based on the results of these tests. Also, the battery is shipped with the initial operating conditions already set. For example, initial operating conditions for the charge / discharge C rate (Current rate), temperature range, and SOC usable range may be set in advance. Therefore, the control unit 130 can change and set the initial operating conditions of the battery based on the condition diagnosis results in order to increase the battery's lifespan.

[0108] The control unit 130 may be configured to reduce at least one of the battery temperature and the upper limit of SOC when the battery state is in an electrolyte side reaction state or a positive electrode degradation state. That is, the control unit 130 can suppress electrolyte decomposition reaction or positive electrode capacity loss by reducing at least one of the battery temperature and the upper limit of SOC. If the control unit 130 diagnoses the battery state as a lithium deposition state, it may set the battery operating conditions so as to suppress the lithium deposition reaction. For example, the control unit 130 may be configured to reduce the upper limit of the battery's charge / discharge C rate.

[0109] If the control unit 130 diagnoses that the battery state is in a negative electrode stabilization state, it does not need to change the battery's operating conditions. In other words, the control unit 130 can maintain the battery's operating conditions as they were set at the time of shipment.

[0110] A battery condition diagnostic device 100 according to one embodiment of the present invention can accurately and quickly diagnose the battery condition based on voltage increase / decrease patterns and resistance increase / decrease patterns. Furthermore, the battery condition diagnostic device 100 can increase the battery life by setting the battery operating conditions to correspond to the condition diagnostic results.

[0111] Preferably, the control unit 130 may be configured to diagnose the battery status each time the voltage profile and resistance profile are updated. That is, the battery operating conditions may be set to optimal conditions that reflect the current state of the battery.

[0112] In general, batteries can degrade due to various side reactions, and the optimal operating conditions corresponding to each side reaction may differ. Therefore, the battery condition diagnostic device 100 has the advantage of being able to increase battery life by quickly and accurately diagnosing the current state of the battery and setting the optimal operating conditions corresponding to the diagnostic results.

[0113] The battery state diagnostic device 100 according to the present invention can be applied to a battery management system (BMS). That is, the BMS according to the present invention may include the battery state diagnostic device 100 described above. In such a configuration, at least some of the components of the battery state diagnostic device 100 can be realized by complementing or adding to the functions of components included in a conventional BMS. For example, the voltage measurement unit 110, resistance measurement unit 120, control unit 130, and recording unit 140 of the battery state diagnostic device 100 can be realized as components of a BMS.

[0114] Furthermore, the battery condition diagnostic device 100 according to the present invention may be provided in a battery pack. That is, the battery pack according to the present invention may include the above-described battery condition diagnostic device 100 and one or more battery cells. The battery pack may further include electrical components (relays, fuses, etc.) and a case, etc.

[0115] Figure 10 is a schematic diagram illustrating an exemplary configuration of a battery pack according to another embodiment of the present invention.

[0116] The positive terminal of battery B may be connected to the positive terminal P+ of battery pack 10, and the negative terminal of battery B may be connected to the negative terminal P- of battery pack 10.

[0117] The voltage measuring unit 110 can be connected to a first sensing line SL1 and a second sensing line SL2. Specifically, the voltage measuring unit 110 can be connected to the positive terminal of battery B through the first sensing line SL1 and to the negative terminal of battery B through the second sensing line SL2. The voltage measuring unit 110 can measure the voltage of battery B based on the voltages measured at the first sensing line SL1 and the second sensing line SL2, respectively.

[0118] The resistance measuring unit 120 can be connected to a pulse line PL. Specifically, the resistance measuring unit 120 can be connected to the positive terminal of battery B via the pulse line PL. The resistance measuring unit 120 can also measure the resistance of battery B by outputting a pulse signal to the pulse line PL.

[0119] For example, in the embodiment shown in Figure 10, the resistance measuring unit 120 can output a pulse signal through the pulse line PL for 0.1 seconds. The voltage measuring unit 110 measures the voltage of battery B for 0.1 seconds, and the resistance measuring unit 120 can calculate the change in battery B voltage during the 0.1 seconds in which the pulse signal is output. The resistance measuring unit 120 can also measure the target resistance of battery B based on the current of the pulse signal and the change in battery B voltage.

[0120] Referring to Figure 10, the voltage measurement unit 110, the resistance measurement unit 120, the control unit 130, and the recording unit 140 can be connected to each other in a way that allows them to communicate with one another.

[0121] On the other hand, the charging device or load may have one end connected to the positive terminal P+ of the battery pack 10 and the other end connected to the negative terminal P- of the battery pack 10. Battery B is charged by the charging device, and the load can receive power from battery B. For example, the load may be the motor of an electric vehicle.

[0122] In other embodiments, the resistance measuring unit 120 may be connected to a current sensor (not shown) included in the battery pack 10. The resistance measuring unit 120 can measure the discharge current of the battery through the current sensor. The resistance measuring unit 120 can also calculate the amount of discharge current over a predetermined period of time from the point when the battery voltage reaches a second reference voltage. The resistance measuring unit 120 can calculate the target resistance using the amount of battery voltage change measured by the voltage measuring unit 110 and the calculated amount of discharge current.

[0123] In other words, the resistance measuring unit 120 may measure the target resistance by directly outputting a pulse signal, or it may measure the target resistance by measuring the discharge current, depending on the embodiment.

[0124] Furthermore, the battery condition diagnostic device 100 according to the present invention can be installed in an automobile. Specifically, a battery pack including the battery condition diagnostic device 100 can be installed in automobiles such as electric vehicles (EVs) and hybrid vehicles (HVs). The battery pack can also drive the automobile by supplying power to the motor through an inverter installed in the automobile.

[0125] Figure 11 is a schematic diagram illustrating an exemplary configuration of an electric vehicle 1100 according to yet another embodiment of the present invention.

[0126] In the embodiment shown in Figure 11, the electric vehicle 1100 may include a battery condition diagnostic device 100 and a battery pack 10. The battery pack 10 can supply power to the motor of the electric vehicle 1100 so that the electric vehicle 1100 can be started and / or driven. Also, if a charging device is connected to the electric vehicle 1100, the battery pack 10 can be charged by the charging device. That is, the electric vehicle 1100 may include a battery condition diagnostic device 100. In this case, the battery condition diagnostic device 100 may be an onboard diagnostic device included in the electric vehicle 1100.

[0127] Furthermore, the battery status diagnostic device 100 according to the present invention may be provided in the energy storage device 1200.

[0128] Figure 12 is a schematic diagram illustrating an exemplary configuration of an energy storage device 1200 according to yet another embodiment of the present invention.

[0129] In the embodiment shown in Figure 12, the energy storage device 1200 may include a battery rack 1210. Preferably, the energy storage device 1200 may include multiple battery racks 1210. One battery rack 1210 may include one or more battery modules 1220. A battery condition diagnostic device 100 is provided in each battery module 1220 and can diagnose the state of one or more battery cells contained in the battery module 1220. The battery condition diagnostic device 100 can also diagnose the state of the battery module 1220 in the same manner as the method used to diagnose the state of the battery.

[0130] Figure 13 is a schematic diagram illustrating a battery condition diagnosis method according to yet another embodiment of the present invention.

[0131] Preferably, each step of the battery condition diagnosis method can be performed by the battery condition diagnosis device 100. In the following, content that overlaps with the above description will be briefly explained or omitted.

[0132] Referring to Figure 13, the battery condition diagnosis method includes a voltage measurement stage S100, a target measurement stage S200, a pattern determination stage S300, and a battery condition diagnosis stage S400.

[0133] The voltage measurement step S100 is a step in which the voltage of the battery is measured, and can be performed by the voltage measurement unit 110.

[0134] The target measurement step S200 is a step in which, if the measured voltage reaches a preset first reference voltage, the target voltage of the battery is measured, and if the measured voltage reaches a preset second reference voltage, the target resistance of the battery is measured, and this step can be performed by the voltage measurement unit 110 and the resistance measurement unit 120.

[0135] Specifically, the voltage measurement unit 110 can measure the target voltage, and the resistance measurement unit 120 can measure the target resistance.

[0136] The voltage measurement unit 110 can measure the target voltage of the battery when the measured voltage reaches the first reference voltage, and the battery has remained in an unloaded state for a certain period of time.

[0137] Furthermore, the resistance measurement unit 120 can calculate the target resistance based on the amount of voltage change and discharge current of the battery over a predetermined period of time once the measured voltage reaches the second reference voltage.

[0138] The pattern determination step S300 is a step in which the voltage increase / decrease pattern for the target voltage is determined based on the voltage profile in which the target voltage is stored, and the resistance increase / decrease pattern for the target resistance is determined based on the resistance profile in which the target resistance is stored, and this step may be performed by the control unit 130.

[0139] The control unit 130 may compare a plurality of target voltages included in the voltage profile and determine a voltage increase / decrease pattern as a first voltage pattern or a second voltage pattern.

[0140] The control unit 130 may compare a plurality of target resistors included in the resistance profile and determine a resistance increase / decrease pattern as a first resistance pattern or a second resistance pattern.

[0141] It should be noted that the order in which the voltage increase / decrease pattern and the resistance increase / decrease pattern are determined is not particularly limited.

[0142] Battery status diagnosis step S400 is a step in which the battery status is diagnosed from voltage increase / decrease patterns and resistance increase / decrease patterns according to a preset diagnostic rule, and can be performed by the control unit 130.

[0143] The control unit 130 can diagnose the battery state in accordance with the determined combination of voltage increase / decrease pattern and resistance increase / decrease pattern. For example, the control unit 130 can diagnose the current state of the battery by referring to the diagnostic rules in Figure 5.

[0144] A battery state diagnosis method according to one embodiment of the present invention can classify and diagnose the state of a battery according to a combination of the battery's voltage increase / decrease pattern and resistance increase / decrease pattern. Since the battery state is diagnosed based on voltage and resistance, the current state of the battery can be diagnosed quickly. Therefore, the present invention has the advantage of being able to diagnose the current state of a battery quickly and accurately.

[0145] The embodiments of the present invention described above are not limited to apparatus and methods, but can also be embodied through a program that realizes the functions corresponding to the configuration of the embodiments of the present invention, or through a recording medium on which such a program is recorded. Such embodiments can be easily realized by those skilled in the art from the description of the embodiments described above.

[0146] As described above, the present invention has been explained with limited embodiments and drawings, but the present invention is not limited thereto, and it goes without saying that various modifications and variations are possible within the equivalent scope of the technical concept and claims of the present invention by persons with ordinary skill in the art to which the present invention pertains.

[0147] Furthermore, the present invention described above can be substituted, modified, and altered in various ways by a person with ordinary skill in the art to which the present invention pertains, without departing from the technical spirit of the invention, and is not limited by the embodiments described above and the accompanying drawings. For diverse modifications, all or part of each embodiment may be selectively combined to form the present invention. [Explanation of symbols]

[0148] 10: Battery Pack 100: Battery status diagnostic device 110: Voltage measurement section 120: Resistance measurement section 130: Control Unit 140: Records Department 1100: Electric vehicle 1200: Energy storage devices 1210: Battery Rack 1220: Battery Module

Claims

1. A voltage measuring unit is configured to measure the voltage of a battery, and if the measured voltage reaches a preset first reference voltage, it measures a target voltage for the battery. A resistance measuring unit configured to measure the target resistance of the battery when the measured voltage reaches a preset second reference voltage, The control unit is configured to determine a voltage increase / decrease pattern based on a plurality of recently stored target voltages in a voltage profile in which the target voltage measured by the voltage measuring unit is stored, and to determine a resistance increase / decrease pattern based on a plurality of recently stored target resistances in a resistance profile in which the target resistance measured by the resistance measuring unit is stored, and to diagnose the state of the battery from the voltage increase / decrease pattern and the resistance increase / decrease pattern according to a preset diagnostic rule, A battery condition diagnostic device, wherein the control unit is configured to determine the voltage increase / decrease pattern as either a voltage increase pattern or a voltage decrease pattern, determine the resistance increase / decrease pattern as either a resistance increase pattern or a resistance decrease pattern, and diagnose the state of the battery differently depending on the combination of the voltage increase / decrease pattern and the resistance increase / decrease pattern.

2. The battery state diagnostic device according to claim 1, wherein the control unit is configured to diagnose the state of the battery as an electrolyte side reaction state, a lithium deposition state, a positive electrode degradation state, or a negative electrode stabilization state.

3. The battery state diagnostic device according to claim 2, wherein the control unit is configured to diagnose the state of the battery as the electrolyte side reaction state when it is determined that the voltage increase / decrease pattern is the voltage increase pattern and the resistance increase / decrease pattern is the resistance increase pattern.

4. The battery state diagnostic device according to claim 2, wherein the control unit is configured to diagnose the state of the battery as the lithium deposition state when it is determined that the voltage increase / decrease pattern is the voltage increase pattern and the resistance increase / decrease pattern is the resistance decrease pattern.

5. The battery condition diagnostic device according to claim 2, wherein the control unit is configured to diagnose the state of the battery as the positive electrode deterioration state when it is determined that the voltage increase / decrease pattern is the voltage decrease pattern and the resistance increase / decrease pattern is the resistance increase pattern.

6. The battery state diagnostic device according to claim 2, wherein the control unit is configured to diagnose the state of the battery as the negative electrode stabilized state when it is determined that the voltage increase / decrease pattern is the voltage decrease pattern and the resistance increase / decrease pattern is the resistance decrease pattern.

7. The battery state diagnostic device according to claim 2, wherein the control unit is configured to set the operating conditions of the battery in accordance with the diagnostic results for the state of the battery.

8. The control unit, If the state of the battery is diagnosed as the electrolyte side reaction state or the positive electrode degradation state, the system is configured to reduce at least one of the battery temperature and the upper limit of SOC. The battery condition diagnostic device according to claim 7, wherein when the state of the battery is diagnosed as the lithium deposition state, it is configured to reduce the upper limit of the charge / discharge C rate of the battery.

9. The battery status diagnostic device according to claim 1, wherein the control unit is configured to diagnose the state of the battery each time the voltage profile and the resistance profile are updated.

10. The battery condition diagnostic device according to claim 1, wherein the resistance measuring unit is configured to measure the target resistance based on the amount of voltage change of the battery over a predetermined period of time when the measured voltage reaches the second reference voltage.

11. The battery state diagnostic device according to claim 1, wherein the first reference voltage is the discharge termination voltage set for the battery.

12. The battery condition diagnostic device according to claim 1, wherein the second reference voltage is a voltage belonging to a preset negative electrode flat section of the usable voltage section of the battery.

13. A battery pack including a battery condition diagnostic device according to any one of claims 1 to 12.

14. The voltage measurement stage measures the battery voltage, A target measurement step is performed in which, when the measured voltage reaches a preset first reference voltage, the target voltage for the battery is measured, and when the measured voltage reaches a preset second reference voltage, the target resistance of the battery is measured. A pattern determination step in which, in a voltage profile in which the target voltage measured in the target measurement step is stored, a voltage increase / decrease pattern is determined based on a plurality of recently stored target voltages, and in a resistance profile in which the target resistance measured in the target measurement step is stored, a resistance increase / decrease pattern is determined based on a plurality of recently stored target resistances, The battery status diagnostic step includes diagnosing the state of the battery from the voltage increase / decrease pattern and the resistance increase / decrease pattern according to a pre-set diagnostic rule, A battery condition diagnosis method, comprising the steps of determining the voltage increase / decrease pattern as a voltage increase pattern or a voltage decrease pattern, determining the resistance increase / decrease pattern as a resistance increase pattern or a resistance decrease pattern, and diagnosing the battery condition differently according to the combination of the voltage increase / decrease pattern and the resistance increase / decrease pattern.

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