Battery management system, battery pack, electric vehicle, and battery management method

Abstract

A battery management system, a battery pack, an electric vehicle, and a battery management method are provided. A battery management system according to the present disclosure includes: a sensing unit configured to measure a cell voltage, a cell current, and a negative resistance of a battery cell; and a control unit configured to determine a state of the battery cell based on a measured value of each of the cell voltage, the cell current, and the negative resistance.

Description

Technical Field

[0001] The present disclosure relates to electrical state estimation of battery cells.

[0002] This application claims priority from Korean Patent Application No. 10-2023-0134642 filed in Korea on October 10, 2023, the disclosure of which is incorporated herein by reference. Background Art

[0003] In recent years, demand for portable electronic products such as laptop computers, cameras, and mobile phones has rapidly increased, and with the widespread development of electric vehicles, accumulators for energy storage, robots, and artificial satellites, much research is being conducted on high-performance batteries that can be repeatedly charged and discharged.

[0004] Currently, commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc., and among them, lithium batteries have little or no memory effect, and therefore lithium batteries have received more attention than nickel-based batteries due to their advantages of being able to complete recharging at their convenience, having a very low self-discharge rate, and having a high energy density.

[0005] Battery packs for applications requiring high capacity and voltage, such as electric vehicles or energy storage systems, consist of dozens to hundreds of battery cells connected in series. A battery management system is required to obtain battery parameters (e.g., voltage, current, state of charge (SOC)) for each cell and perform various functions (e.g., balancing, cooling) to ensure the reliability and safety of each battery.

[0006] Currently, various types of rechargeable battery cells are widely used, and some of them, such as lithium iron phosphate (LFP) cells and lithium sulfur (LiS) cells, have voltage plateau characteristics in a portion (eg, 5% to 70%) of the entire SOC range.

[0007] The voltage plateau range may be an SOC range in which a change in open circuit voltage (OCV) is equal to or less than a threshold value in an SOC-OCV curve and / or an SOC range in which a change in closed circuit voltage (CCV) is equal to or less than a threshold value during constant current charge or discharge, the SOC-OCV curve being a data set indicating a relationship between SOC and OCV.

[0008] When a battery cell has a voltage plateau characteristic, the SOC-OCV curve (referred to as an "OCV plot") and / or the SOC-CCV curve (referred to as a "CCV plot") are useful for SOC estimation outside the voltage plateau range, but within the voltage plateau range, even a small error in OCV or CCV may result in a large difference between the actual SOC and its estimated SOC.

[0009] Therefore, when the SOC of a battery cell is within a voltage plateau range (SOC range having a voltage plateau characteristic), it may be advantageous to determine the estimated SOC of the current cycle of the battery cell based on the current integration of the battery cell rather than the OCV map or CCV map.

[0010] However, during alternating charging and discharging, when the SOC of a battery cell is maintained within a voltage plateau range for a long period of time, the error between the actual current value of the battery cell and the detected current value may accumulate in the current integration, and the accuracy of the SOC estimation may decrease. In addition, SOC is considered to be a very important factor in estimating the state of health (SOH) of a battery cell, so an inaccurately estimated SOC may reduce the accuracy of the SOH.

[0011] One technical solution to this problem is to estimate the SOC of a battery cell using an OCV diagram or a CCV diagram after intentionally charging or discharging the battery cell so that the SOC of the battery cell moves outside the voltage plateau range. However, the above method has problems in that power is unnecessarily wasted due to the intentional charging or discharging of the battery cell, and it takes a longer time to estimate the SOC. Summary of the Invention

[0012] Technical issues

[0013] Through many experiments, the inventors have realized that there is a strong correspondence between the state of charge (SOC) of a battery cell and the negative electrode resistance.

[0014] The present disclosure is designed to solve the above-mentioned problems, and therefore the present disclosure aims to provide a battery management system, a battery pack, an electric vehicle and a battery management method for suppressing the degradation of SOC estimation accuracy caused by voltage platform characteristics by using SOC estimation logic that uses the negative electrode resistance of a battery cell as an input variable (the second SOC estimation logic described below).

[0015] These and other purposes and advantages of the present disclosure can be understood from the following description and will become apparent from the exemplary embodiments of the present disclosure.In addition, it will be easily understood that the purposes and advantages of the present disclosure can be achieved by the means set forth in the appended claims and their combinations.

[0016] Technical Solution

[0017] A battery management system according to one aspect of the present disclosure includes: a sensing unit configured to measure a cell voltage, a cell current, and a negative electrode resistance of a battery cell; and a control unit configured to determine a state of the battery cell based on the measured value of each of the cell voltage, the cell current, and the negative electrode resistance.

[0018] The control unit may be configured to determine a first estimated state of charge (SOC) based on a measured value of each of a cell voltage and a cell current by executing a first SOC estimation logic. The control unit may be configured to determine a second estimated SOC based on a measured value of a negative electrode resistance by executing a second SOC estimation logic. The control unit may be configured to determine an estimated SOC for a current cycle of the battery cell based on at least one of the first estimated SOC and the second estimated SOC.

[0019] The control unit may be configured to determine the current cycle estimated SOC of the battery cell to be equal to either one of the first estimated SOC and the second estimated SOC or a weighted average of the first estimated SOC and the second estimated SOC according to a result of comparing the first estimated SOC with the voltage plateau range.

[0020] The control unit may be configured to determine the estimated SOC of a current cycle of the battery cell to be equal to the first estimated SOC when the first estimated SOC is outside the voltage plateau range.

[0021] The control unit may be configured to determine the estimated SOC of a current cycle of the battery cell to be equal to the second estimated SOC when the first estimated SOC is within the voltage plateau range.

[0022] The control unit may be configured to determine a first weight associated with the first SOC estimation logic and a second weight associated with the second SOC estimation logic based on a difference between the voltage plateau range and the first estimated SOC when the first estimated SOC is outside the voltage plateau range. The control unit may be configured to determine the estimated SOC of the battery cell for a current cycle to be equal to a weighted average of the first estimated SOC and the second estimated SOC based on the first weight and the second weight.

[0023] The first weight may have a predetermined positive correlation with the difference between the voltage plateau range and the first estimated SOC. The second weight may have a predetermined negative correlation with the difference between the voltage plateau range and the first estimated SOC.

[0024] The control unit may be configured to determine the estimated SOC of the current cycle of the battery cell to be equal to a weighted average of the first estimated SOC and the second estimated SOC based on the third weight and the fourth weight when the first estimated SOC is within the voltage plateau range.

[0025] The control unit may be configured to determine a first weight associated with the first SOC estimation logic and a second weight associated with the second SOC estimation logic based on a difference between the voltage plateau range and the first estimated SOC when the first estimated SOC is outside the voltage plateau range. The control unit may be configured to determine the first weight and the second weight based on a retention time of the SOC within the voltage plateau range. The third weight may have a predetermined negative correlation with the retention time. The fourth weight may have a predetermined positive correlation with the retention time.

[0026] The control unit may be configured to determine a current estimated SOH of the battery cell based on a measured value of each of a negative electrode resistance and a cell temperature of the battery cell when the estimated SOC of the current cycle indicates a fully discharged or fully charged state.

[0027] A battery pack according to another aspect of the present disclosure may include the battery management system.

[0028] An electric vehicle according to still another aspect of the present disclosure may include the battery pack.

[0029] A battery management method according to still another aspect of the present disclosure includes measuring a cell voltage, a cell current, and a negative electrode resistance of a battery cell, and determining a state of the battery cell based on the measured value of each of the cell voltage, the cell current, and the negative electrode resistance.

[0030] The step of determining the electrical state of the battery cell may include the steps of determining a first estimated state of charge (SOC) based on a measured value of each of a cell voltage and a cell current by executing a first SOC estimation logic, determining a second estimated SOC based on a measured value of a negative electrode resistance by executing a second SOC estimation logic, and determining an estimated SOC for a current cycle of the battery cell based on at least one of the first estimated SOC and the second estimated SOC.

[0031] The step of determining the estimated SOC of the current cycle of the battery cell may include the following steps: based on the result of comparing the first estimated SOC with the voltage platform range, determining the estimated SOC of the current cycle of the battery cell to be equal to either one of the first estimated SOC and the second estimated SOC or a weighted average of the first estimated SOC and the second estimated SOC.

[0032] Beneficial effects

[0033] According to at least one of the embodiments of the present disclosure, it is possible to suppress a decrease in the accuracy of state of charge (SOC) estimation caused by voltage platform characteristics by estimating the SOC of a battery cell by using an additional SOC estimation logic (hereinafter referred to as the "second SOC estimation logic") that uses the negative electrode resistance of the battery cell as an input variable together with a commonly used SOC estimation logic (hereinafter referred to as the "first SOC estimation logic").

[0034] In addition, according to at least one of the embodiments of the present disclosure, the SOC estimation accuracy in the entire SOC range can be improved by ultimately determining either the estimated SOC of the first SOC estimation logic and the estimated SOC of the second SOC estimation logic, or a weighted average of them based on the difference between the estimated SOC of the first SOC estimation logic and the voltage platform range as the SOC of the battery cell.

[0035] In addition, according to at least one of the embodiments of the present disclosure, the accuracy of SOC estimation in the entire SOC range can be improved by determining the weight of each of the estimated SOC of the first SOC estimation logic and the estimated SOC of the second SOC estimation logic based on the retention time of the estimated SOC of the first SOC estimation logic within or outside the voltage platform range, and ultimately determining the SOC of the battery cell to be equal to the weighted average of the two estimated SOCs by the two weights.

[0036] The effects of the present disclosure are not limited to the aforementioned effects, and those skilled in the art will clearly understand these and other effects from the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the following detailed description, serve to provide a better understanding of the technical aspects of the present disclosure, and thus the present disclosure should not be construed as limited to the accompanying drawings.

[0038] Figure 1 is a diagram exemplarily illustrating an electric vehicle including a battery management system according to the present disclosure.

[0039] Figures 2a to 2c These are the drawings referred to when describing the internal / external structure of a battery cell.

[0040] Figure 3 is a graph exemplarily showing a state of charge (SOC)-open circuit voltage (OCV) curve of a battery cell.

[0041] Figure 4 FIG. 1 is a diagram exemplarily showing an SOC-negative electrode resistance curve of a battery cell.

[0042] Figure 5It is a graph used to describe the relationship between the state of health (SOH) of a battery cell and the SOC-negative electrode resistance curve.

[0043] Figure 6 is an example showing that Figure 1 Flowchart of a battery management method executed by a battery management system shown in FIG.

[0044] Figure 7 It is shown as an example Figure 6 Flowchart of the subroutine of step S620 in .

[0045] Figure 8 It is schematically shown Figure 7 Flowchart of an example of the subroutine of step S730 in FIG.

[0046] Figure 9 It is schematically shown Figure 7 Flowchart of another example of the subroutine of step S730 in .

[0047] Figure 10 Shows that when executing Figure 9 The method is an example of a weight map that can be used.

[0048] Figure 11 It is schematically shown Figure 7 Flowchart of another example of the subroutine of step S730 in .

[0049] Figure 12 An example of a first correction coefficient map for correcting the first weight is shown.

[0050] Figure 13 An example of a second correction coefficient map for correcting the fourth weight is shown.

[0051] Figure 14 is a flowchart exemplarily illustrating a battery management method according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0052] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in this specification and the appended claims should not be understood as limited to the general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that allows the inventor to appropriately define the terms for the best interpretation.

[0053] Therefore, the embodiments described herein and the illustrations shown in the accompanying drawings are exemplary embodiments of the present disclosure for describing the technical aspects of the present disclosure and are not intended to be limiting, and it should be understood that various other equivalents and modifications may be made thereto when an application is filed.

[0054] Terms including ordinal numbers such as “first,” “second,” etc. are used to distinguish one element from another among various elements, but are not intended to limit the elements by the terms.

[0055] Unless the context clearly indicates otherwise, the terms "comprise" and "include" as used in this specification specify the presence of the stated elements, but do not exclude the presence or addition of one or more other elements. In addition, the term "control unit" as used herein refers to a processing unit of at least one function or operation, and can be implemented by hardware and software alone or in combination.

[0056] Furthermore, throughout the specification, it will be understood that when an element is referred to as being “connected to” another element, it can be directly connected to the other element or intervening elements may be present.

[0057] In the specification, the state of charge (SOC) refers to the ratio of the remaining capacity of an energy storage unit (eg, a battery cell, a cell group) to the fully charged capacity, and is expressed as 0% to 100%.

[0058] Figure 1 is a diagram exemplarily illustrating an electric vehicle including a battery management system according to the present disclosure.

[0059] refer to Figure 1 , the electric vehicle 1 includes a vehicle controller 2 , a battery pack 10 , an inverter 30 and a motor 40 .

[0060] The charge / discharge terminals P+, P- of the battery pack 10 may be electrically coupled to the inverter 30 and / or the charger 3 through a cable. The charger 3 may be included in the electric vehicle 1 or may exist in a charging station outside the electric vehicle 1.

[0061] The vehicle controller 2 (e.g., an electronic control unit (ECU)) is configured to transmit a key-on signal to the battery management system 100 in response to a user turning a start button (not shown) of the electric vehicle 1 to the on position. The vehicle controller 2 is configured to transmit a key-off signal to the battery management system 100 in response to a user turning the start button to the off position. The charger 3 can supply charging power (e.g., constant current, constant voltage, constant power) through the charge / discharge terminals P+, P− of the battery pack 10 via communication with the vehicle controller 2.

[0062] The battery pack 10 includes battery cells BC and a relay 20 , and may further include a battery management system 100 .

[0063] A battery cell BC may be, for example, an energy storage device that can be repeatedly charged and discharged and has a voltage plateau characteristic, such as a lithium iron phosphate (LFP) cell or a lithium sulfur (LiS) cell. The voltage plateau range is a preset or identified SOC range within which the voltage change of the battery cell BC is less than a threshold.

[0064] The following will refer to Figures 2a to 2c The structure of the battery cell BC is described in further detail.

[0065] The series circuit of the battery cell BC, the current sensor 113 and the relay 20 is electrically connected to the inverter 30 and / or the charger 3 through the charge / discharge terminals P+, P−.

[0066] The relay 20 is mounted on a power path that serves as a current path for charging and discharging the battery pack 10. When the relay 20 is turned on, power can be transferred from the battery pack 10 to the inverter 30 and / or from the charger 3 to the battery pack 10. The relay 20 may include any one or a combination of two or more known switching devices, such as a mechanical contactor or a field effect transistor (FET). The control unit 130 may control the relay 20 from one of an on state and an off state to the other.

[0067] The inverter 30 is provided to convert direct current from the battery group 11 included in the battery pack 10 into alternating current in response to a command from the battery management system 100 or the vehicle controller 2. The motor 40 can operate using the alternating current from the inverter 30. The motor 40 may include, for example, a three-phase AC motor.

[0068] The voltage across the battery cell BC may be referred to as a “cell voltage.” The state of the battery cell BC being charged / discharged by turning on the relay 20 may be referred to as a load (cycle). The voltage of the battery cell BC detected under load may be referred to as a closed circuit voltage (CCV).

[0069] When the relay 20 changes from the on state to the off state, the battery cell BC is under no load (at rest, in the calendar). The voltage across the battery cell BC under no load can be referred to as the no-load voltage. The no-load voltage is collectively referred to as the relaxation voltage and the open circuit voltage (OCV). Specifically, when the battery cell BC changes from load to no load, the polarized battery cell BC begins to depolarize spontaneously, and the no-load voltage of the battery cell BC converges to the OCV. OCV indicates the no-load voltage when the battery cell BC is kept under no load for more than a predetermined time (for example, 2 hours) and the change in the voltage of the battery cell BC is less than a predetermined value. That is, OCV is the no-load voltage when the polarization of the battery cell BC is reduced to a negligible level. The relaxation voltage is the no-load voltage before the polarization is sufficiently reduced.

[0070] The battery management system 100 is provided to monitor the conditions of the battery cells BC.

[0071] The battery management system 100 includes a sensing unit 110 and a control unit 130. The battery management system 100 may further include a communication unit 150.

[0072] The sensing unit 110 includes a voltage sensor 111, a current sensor 113, and a resistance sensor 115. The sensing unit 110 may further include a temperature sensor 117.

[0073] A voltage sensor 111 is provided and electrically connected to the positive lead and the first negative lead of the battery cell BC. The voltage sensor 111 detects the cell voltage of the battery cell BC using a change in potential between a pair of sensing lines, each of which is connected to the positive lead PL and the first negative lead NL of the battery cell BC. The voltage sensor 111 can transmit a voltage signal indicating the detected cell voltage of the battery cell BC to the control unit 130 through analog-to-digital conversion.

[0074] The current sensor 113 is connected in series with the battery cell BC through the charge / discharge current path of the battery cell BC. The current sensor 113 may include one or a combination of two or more known current sensors such as a shunt resistor or a Hall effect device.

[0075] The current sensor 113 may be configured to generate and output a current signal indicating a cell current or a charge / discharge current flowing between the positive lead PL and the first negative lead NL of the battery cell BC to the control unit 130 .

[0076] The resistance sensor 115 may be connected between the first negative lead NL and the second negative lead AL of the battery cell BC and provided to measure the negative electrode resistance of the battery cell BC. The resistance sensor 115 may include, for example, an electrochemical impedance spectroscopy (EIS) device.

[0077] EIS is a method that applies an alternating current (AC) voltage to an object (i.e., a battery cell) and measures the object's resistance by analyzing the response signal to the applied AC voltage. This method allows for more accurate analysis than constant current or constant voltage measurement methods. The AC voltage amplitude can range from 0.01mV to 0.5mV, 0.01mV to 0.2mV, or 0.2mV to 0.5mV. When the AC voltage amplitude falls within these ranges, resistance measurement accuracy is improved and damage to the battery cells (BC) can be prevented.

[0078] In an embodiment of the present disclosure, the frequency of the AC voltage used to measure the resistance may range from 100 Hz to 1000 Hz.

[0079] During the charge / discharge period of a battery cell BC, as the negative electrode of the battery cell BC expands or contracts, the thickness of the negative electrode of the battery cell BC also changes. Specifically, during charge, as the negative electrode of the battery cell BC expands, the thickness of the negative electrode increases. Conversely, during discharge, as the negative electrode of the battery cell BC contracts, the thickness of the negative electrode decreases. The resistance sensor 115 may be configured to output a signal indicating the resistance of the negative electrode to the control unit 130 during the charge / discharge period of the battery cell BC.

[0080] It is known that the resistance of a conductor is inversely proportional to its thickness. Furthermore, the present inventors have recognized that the thickness of the negative electrode of a battery cell BC has a unique relationship with the SOC, based on the changing pattern of the thickness of the negative electrode of the battery cell BC during charge and discharge. This demonstrates that the resistance of the negative electrode of a battery cell BC is an indicator that strongly depends on the SOC of the battery cell BC.

[0081] The sensor 117 may be directly attached to the outer package of the battery cell BC or may be spaced apart from the outer package of the battery cell BC by a predetermined distance. The temperature sensor 117 may be configured to output a temperature signal indicating the temperature of the battery cell BC to the control unit 130. The temperature sensor 117 may include, for example, a thermocouple.

[0082] The control unit 130 is operatively coupled to the relay 20, the sensing unit 110, the memory 140 and / or the communication unit 150. Operably coupled refers to a direct / indirect connection to enable signal transmission and reception in one or two directions.

[0083] The control unit 130 may be implemented in hardware using at least one of a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions.

[0084] The memory 140 may pre-store programs and data necessary for executing the battery management method according to the embodiments described below. The memory may include, for example, at least one type of computer-readable storage medium selected from a flash memory type, a hard disk type, a solid-state disk (SSD) type, a silicon disk drive (SDD) type, a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable read-only memory (PROM). Although Figure 1It is illustrated that the memory 140 is provided independently of the control unit 130 , but the memory 140 may be provided in the control unit 130 in an embedded form.

[0085] Based on the voltage, current, temperature, and resistance signals received from the sensing unit 110, the control unit 130 can determine the voltage, current, temperature, and negative electrode resistance values ​​every set time (e.g., 0.01 seconds) and record these values ​​in the memory 140. Because the current signal includes current direction information, the control unit 130 can determine whether the battery cell BC is being charged, discharged, or resting based on the current signal. Resting (or resting) indicates that charging and discharging of the battery pack 10 has been stopped.

[0086] The control unit 130 may determine the current accumulation amount by ampere counting (current integration) based on the current signal. The current accumulation amount at a certain time point refers to the total current accumulated over a period of time from the last time the current accumulation amount was initialized before the corresponding time point to the corresponding time point.

[0087] The communication unit 150 can be coupled to the vehicle controller 2 of the electric vehicle 1 to enable communication between the two. The communication unit 150 can transmit messages from the vehicle controller 2 to the control unit 130, and vice versa. Messages from the control unit 130 may include information regarding the electrical status of the battery cells (BC) (e.g., State of Charge, State of Hygiene). For example, a wired network such as a local area network (LAN), a controller area network (CAN), or a daisy chain, and / or a short-range wireless network such as Bluetooth, Zigbee, or WiFi, can be used for communication between the communication unit 150 and the vehicle controller 2. The battery management system 100 may also include an output device (e.g., a display, a speaker) to provide information received by the communication unit 150 from the control unit 130 and / or the vehicle controller 2 in a recognizable format. The vehicle controller 2 can control the inverter 30 and / or the charger 3 based on the information collected through communication with the battery management system 100.

[0088] Figures 2a to 2c The figure is referred to when describing the internal / external structure of the battery cell. Specifically, Figure 2a This is the top view of the battery cell BC. Figure 2b is a side cross-sectional view of a battery cell BC, and Figure 3 b shows the structure of the negative electrode plate 12 of the battery BC.

[0089] refer to Figures 2a to 2c , the battery cell BC includes an outer package E and an electrode assembly EA.

[0090] The outer package E provides a space in which the electrode assembly EA can be accommodated. Once the electrode assembly EA is placed in the outer package E, a sealing process (e.g., thermal bonding) is performed on the side of the outer package E to complete the manufacture of the battery cell BC. Symbol S indicates the sealed side of the outer package E.

[0091] The electrode assembly EA includes a positive electrode lead PL, a positive electrode plate 11, a separator 13, a first negative electrode lead NL, a second negative electrode lead AL, and a negative electrode plate 12. The electrode assembly EA includes at least one positive electrode plate 11, at least one negative electrode plate 12, and at least one separator 13 stacked or folded in a predetermined pattern. The positive electrode plate 11 and the negative electrode plate 12 are electrically insulated from each other by the separator 13.

[0092] The positive electrode tab PT protrudes from the positive electrode plate 11 toward the positive electrode lead PL. Similarly, the first negative electrode tab NT and the second negative electrode tab AT protrude from different areas of the negative electrode plate 12 toward the first negative electrode lead NL and the second negative electrode lead AL, respectively. For example, the first negative electrode tab NT protrudes from one edge of the negative electrode plate in the same direction as the positive electrode tab PT, while the second negative electrode tab AT protrudes from the other edge of the negative electrode plate in a direction opposite to that of the first negative electrode tab NT, the other edge being located on the opposite side of the protruding edge of the first negative electrode tab NT.

[0093] One end of each of the positive electrode tab PT, the first negative electrode tab NT, and the second negative electrode tab AT is individually coupled to one end of the positive lead PL, the first negative electrode lead NL, and the second negative electrode lead AL inside the outer package E. The other end of each of the positive lead PL, the first negative electrode lead NL, and the second negative electrode lead AL is exposed outside the outer package E.

[0094] The negative electrode plate 12 may include a lithium metal foil connected to the first negative electrode tab NT and the second negative electrode tab AT. The negative electrode plate 12 may include only the lithium metal foil without including a current collector plate. In this case, the lithium metal foil may be an independent type responsible for the function of a current collector plate commonly used in the art.

[0095] The other end of each of the positive lead PL and the first negative lead NL serves as a positive terminal and a negative terminal for charging / discharging the battery cell BC, respectively. A voltage sensor 111 is connected to the positive terminal and the negative terminal of the battery cell BC to measure the cell voltage of the battery cell BC.

[0096] The other end of the second negative lead AL serves as an auxiliary terminal of the battery cell BC. The resistance sensor 115 is connected between the negative terminal NL of the battery cell BC and the auxiliary terminal AL to measure the negative electrode resistance of the battery cell BC.

[0097] As described above, the first negative electrode tab NT and the second negative electrode tab AT protrude from two opposite edges of the negative electrode plate 12 , and the first negative electrode lead NL and the second negative electrode lead AL are coupled to the first negative electrode tab NT and the second negative electrode tab AT, respectively.

[0098] Therefore, compared with a structure in which the first negative electrode tab NT and the second negative electrode tab AT protrude from the same edge of the negative electrode plate 12 , the negative electrode resistance measured by the resistance sensor 115 can fully reflect the real state of the negative electrode plate 12 .

[0099] The positive electrode plate 11 includes a positive current collector and a positive active material. The positive active material may include a sulfur-carbon composite. The sulfur-carbon composite may include at least one of sulfur or a sulfur-based compound. Here, sulfur-based compounds may be collectively referred to as materials containing sulfur (S).

[0100] The sulfur-based compound may include, for example, all sulfur-containing compounds that can be formed by a reduction reaction of inorganic sulfur (S8) or an oxidation reaction of lithium sulfide (Li2S), and more specifically, may include lithium sulfide (Li2S), lithium polysulfide (Li2Sx, an integer of 2≤x≤8), disulfide, carbon sulfur polymer (C2S y ) n , y=2.5 to 50, n≥2) or two or more thereof.

[0101] The positive electrode active material may be applied to at least one surface of the positive electrode current collector. The positive electrode current collector may include, for example, copper, stainless steel, aluminum, nickel, titanium, palladium, sintered carbon, copper or stainless steel treated with carbon, nickel or silver on the surface, or aluminum-cadmium alloy.

[0102] The loading amount of the positive electrode active material may be 1 to 2.5 times that of the negative electrode active material. When the loading amounts of the positive electrode active material and the negative electrode active material are within the above ranges, the battery cell BC may be evaluated as having sufficient energy density and lifespan.

[0103] The lithium metal foil of the negative electrode plate 12 may include a lithium alloy. The lithium alloy may include elements that form an alloy with lithium. The elements that form an alloy with lithium may include, for example, Si, Sn, C, Pt, Ir, Ni, Cu, Ti, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Sb, Pb, In, Zn, Ba, Ra, Ge, or Al.

[0104] like Figure 2c As shown in FIG, assuming that the shape of the negative plate 12 is substantially rectangular, the negative plate 12 can be divided into four areas A1, A2, B1, and B2 based on the center line of the negative plate 12 in the width direction and the center line of the negative plate 12 in the length direction.

[0105] Region A1 and region B1, as well as region A2 and region B1, are line-symmetrical with respect to the center line in the longitudinal direction. Additionally, region A1 and region B2, as well as region A2 and region B1, are point-symmetrical.

[0106] The first negative electrode tab NT and the second negative electrode tab AT of the battery cell BC can be connected to two point-symmetrical areas A2 and B1, respectively, among the areas A1, A2, B1, and B2 defined by the negative electrode plate 12, and protrude in opposite directions. Therefore, since the distance between the first negative electrode tab NT and the second negative electrode tab AT can be maximized, the negative electrode resistance measured by the resistance sensor 115 can accurately represent the actual negative electrode resistance.

[0107] Figure 3 is a diagram exemplarily showing an SOC-OCV curve of a battery cell, Figure 4 is a diagram exemplarily showing an SOC-negative electrode resistance curve of a battery cell, and Figure 5 This is a graph referenced when describing the relationship between the SOH and SOC-negative electrode resistance curves of a battery cell.

[0108] refer to Figure 3 , the memory 140 stores first relationship data including the SOC-OCV curve 300 .

[0109] The SOC-OCV curve 300 can be mapped to a specific temperature range and a specific SOH range. The SOC-OCV curve 300 records the voltage plateau range (Z A ~Z B As an example, the starting SOC of the voltage plateau range (Z A ) and terminate SOC (Z B ) can be 5% and 70% respectively. For reference, the SOC-OCV curve can be simply referred to as the "OCV graph". For reference, Figure 3 Shows a single voltage platform range Z A ~Z B , but depending on the electrochemical specifications of the battery cell BC, there may be two or more voltage platform ranges.

[0110] When multiple temperature ranges are predefined, the memory 140 may store first relationship data prepared separately for each temperature range. The control unit 130 may retrieve the first relationship data associated with a single temperature range to which the temperature value (measured cell temperature) of the battery cell BC belongs from the memory 140 among the multiple temperature ranges and use the data to estimate the SOC.

[0111] Similarly, when multiple SOH ranges are predefined, the memory 140 may store first relationship data prepared separately for each SOH range. The control unit 130 may retrieve the first relationship data associated with a single SOH range to which the SOH of the battery cell BC belongs from the memory 140 among the multiple SOH ranges and use it to estimate the SOC. For reference, the SOH may be referred to as the capacity retention rate.

[0112] For example, when the number of temperature ranges is 10 and the number of SOH ranges is 20, a total of 200 first relationship data may be pre-stored in the memory 140 , and the SOC-OCV curve 300 may be a data set included in any one of the total 200 first relationship data.

[0113] The OCV of the battery cell BC is within the voltage platform range (Z A ~Z B ) is maintained almost uniformly. That is, within the voltage platform range (Z A ~Z B ), the OCV is maintained below a predetermined reference value according to a change in the SOC (eg, a differential value).

[0114] On the contrary, in the voltage platform range (Z A ~Z B ) and the rest of the range (0~Z A %,Z B 100%), the change in OCV according to SOC is greater than a predetermined reference value. Thus, when OCV is identified, the SOC corresponding to the identified OCV can be determined with high accuracy according to the SOC-OCV curve 300.

[0115] It is known that most rechargeable batteries (including battery cells BC) deteriorate faster when they are continuously used (charged / discharged) at or near SOC 0% or SOC 100% outside the optimal range. The safe voltage range (V1-V2) is preset based on the relationship between the SOC of the battery cell BC and the degradation rate. The SOC (Z1) corresponding to the lower limit V1 of the safe voltage range V1-V2 is smaller than the starting SOC (Z A ) corresponds to the OCV. The SOC (Z2) corresponding to the upper limit V2 of the safe voltage range V1~V2 is higher than the termination SOC (Z B The SOC range Z1-Z2 corresponding to the safe voltage range (V1-V2) can be called a safe range.

[0116] The control unit 130 regularly estimates the SOC of the battery cell BC at each set time, and the estimated SOC of the current cycle is greater than the starting SOC (Z A) is smaller than the set value, or the estimated SOC of the current cycle is smaller than the termination SOC (Z B ) exceeds a set value (e.g., exceeds a safe range), the resistance sensor 115 may be deactivated. That is, when obtaining an estimated SOC, if the SOC-negative electrode resistance curve 400 described below is not needed or is rarely needed, when the resistance sensor 115 is deactivated, the power required to operate the resistance sensor 115 can be saved, and the computational load required to process the measured negative electrode resistance can be reduced.

[0117] Meanwhile, during the charge / discharge of a battery cell BC containing a specific material (e.g., lithium metal) in its electrodes, intercalation or deintercalation reactions of working ions (e.g., lithium ions) occur in the electrode grid, causing volume changes. Therefore, the present inventors have recognized that the time-dependent change in the negative electrode resistance of the battery cell BC detected by the resistance sensor 115 has sufficient correlation with the time-dependent change in the SOC of the battery cell BC.

[0118] refer to Figure 4 Memory 140 stores second relationship data including an SOC-negative electrode resistance curve 400 indicating a relationship between the SOC and the negative electrode resistance of the battery cell BC. The SOC-negative electrode resistance curve 400 can be mapped to a specific temperature range and a specific SOH range. The SOC-negative electrode resistance curve can be referred to as a "negative electrode resistance map."

[0119] When multiple temperature ranges are predefined, the memory 140 may record second relationship data prepared separately for each temperature range. The control unit 130 may obtain the second relationship data associated with a single temperature range to which the temperature value of the battery cell BC belongs from the memory 140 among the multiple temperature ranges and use it to estimate the SOC.

[0120] Similarly, when multiple SOH ranges are predefined, the memory 140 may store second relationship data prepared separately for each SOH range. The control unit 130 may retrieve the second relationship data associated with a single SOH range to which the SOH of the battery cell BC belongs from the memory 140, and use this data to estimate the SOC. For example, when the number of temperature ranges is 10 and the number of SOH ranges is 20, a total of 200 second relationship data may be pre-stored in the memory 140, and the SOC-negative electrode resistance curve 400 may be a data set included in any of the 200 second relationship data.

[0121] according to Figure 4 As shown in the SOC-negative electrode resistance curve 400, it can be seen that as the SOC of the battery cell BC increases from 0% to 100%, the negative electrode resistance of the battery cell BC gradually decreases. Figure 3 In contrast to the SOC-OCV curve 300 shown in FIG, the negative electrode resistance varies in the voltage platform range (Z A ~Z B For reference, the SOC-negative electrode resistance curve 400 may be the result of applying curve fitting logic (e.g., a polynomial) to a plurality of data points created by repeatedly measuring the SOC and negative electrode resistance of a plurality of test cells having the same specifications as the battery cell BC.

[0122] Therefore, when the SOC of the battery cell BC is estimated to be within the voltage platform range (Z A ~Z B ), the SOC of the battery cell BC can be estimated with high accuracy by using the SOC-negative electrode resistance curve 400 alone, or a combination of the SOC-OCV curve 300 and the SOC-negative electrode resistance curve 400 instead of the SOC-OCV curve 300.

[0123] refer to Figure 5 , the memory 140 stores third relationship data including at least one of the SOH-negative electrode resistance curve 510 or the SOH-negative electrode resistance curve 520 of the battery cell BC.

[0124] When multiple temperature ranges are predefined, the memory 140 may store third relationship data prepared separately for each of the multiple temperature ranges. The control unit 130 may retrieve the third relationship data mapped to the temperature values ​​(measured cell temperatures) of the battery cells BC in the multiple temperature ranges from the memory 140 and use it to estimate the SOC.

[0125] Figure 5 The SOH-negative electrode resistance curve 510 shown in FIG. exemplarily represents the relationship between the SOH and the negative electrode resistance of the battery cell BC in a fully discharged state (e.g., SOC 0%). Additionally, the SOH-negative electrode resistance curve 520 exemplarily represents the relationship between the SOH and the negative electrode resistance of the battery cell BC in a fully charged state (e.g., SOC 100%). Even if the SOH of the battery cell BC is equal to a certain value, as the SOC of the battery cell BC increases, the negative electrode resistance of the battery cell BC gradually decreases as described above, and as can be seen from FIG. Figure 5 This can be seen from the two curves 510 and 520 in FIG.

[0126] The control unit 130 may determine the SOH of the battery cell BC by executing at least one of the first SOH estimation logic or the second SOH estimation logic.

[0127] The first SOH estimation logic may include any one of a variety of known SOH estimation logics, or a combination of two or more. For example, the control unit 130 may calculate the current maximum capacity of the battery cell BC by dividing the accumulated current over a specific time period or period by the change in SOC over the same time period. The control unit 130 may then determine the estimated SOH as a percentage of the value obtained by dividing the maximum capacity of the battery cell BC by the designed capacity (maximum capacity at BOL) of the battery cell BC. The first estimated SOH is the estimated SOH obtained by executing the first SOH estimation logic.

[0128] When the battery cell BC is in a fully discharged or charged state, the control unit 130 can estimate the SOH of the battery cell BC based on the measured cell temperature and measured negative electrode resistance of the battery cell BC according to the third relationship data by executing the second SOH estimation logic. That is, the second SOH estimation logic can search the third relationship data for the SOH mapped to each of the measured cell temperature and measured negative electrode resistance of the battery cell BC. Curve 510 of the third relationship data can be used when the battery cell BC is in a fully discharged state, and curve 520 of the third relationship data can be used when the battery cell BC is in a fully charged state. The second SOH refers to the estimated SOH obtained by executing the second SOH estimation logic.

[0129] When a battery cell BC is under load, the control unit 130 can determine (estimate) the OCV of the battery cell BC based on each of the measured cell voltage, measured cell current, and / or measured cell temperature collected from the sensing unit 110. For example, according to Ohm's law, the estimated OCV of the battery cell BC can be calculated by subtracting the voltage value corresponding to the product of the battery cell BC current value and the internal resistance of the battery cell BC from the battery cell BC voltage value. The control unit 130 can determine the internal resistance of the battery cell BC based on the ratio between the change in the battery cell BC voltage and the change in the battery cell BC current at each set time according to Ohm's law. Alternatively, the internal resistance of the battery cell BC can be determined based on an internal resistance map that defines the relationship between the battery cell BC SOC, temperature, and internal resistance.

[0130] Figure 6 The flowchart exemplarily shows the battery management method according to the first embodiment of the present disclosure. When the battery cell BC is being charged / discharged or the rest time during which the battery cell BC is maintained at rest is less than the predetermined stabilization time, the battery management system 100 may periodically repeat the execution at each set time. Figure 6For reference, when the rest time is not long enough, even if the battery cell BC is at rest, there may be a non-negligible difference between the measured cell voltage of the battery cell BC detected by the voltage sensor 111 and the actual OCV of the battery cell BC.

[0131] refer to Figures 1 to 6 In step S610, the control unit 130 uses the sensing unit 110 to measure the cell voltage, cell current, and negative electrode resistance of the battery cell BC. That is, the control unit 130 may collect sensing signals from the sensing unit 110, indicating the measured values ​​of each of the cell voltage, cell current, and negative electrode resistance of the battery cell BC. In this example, the control unit 130 may also collect the measured cell temperature of the battery cell BC.

[0132] In step S620, the control unit 130 determines the electrical state of the battery cell BC based on the measured values ​​of each of the cell voltage, cell current, and negative electrode resistance of the battery cell BC. The electrical state includes SOC and may also include SOH.

[0133] Figure 7 It is shown as an example Figure 6 Flowchart of the subroutine of step S620 in .

[0134] refer to Figures 1 to 7 , in step S710 , the control unit 130 determines a first estimated SOC based on each of the measured cell voltage and the measured cell current by executing a first SOC estimation logic.

[0135] The first SOC estimation logic may include any one or a combination of two or more of known SOC estimation logics (eg, OCV map, ampere counting (current integration), Kalman filtering).

[0136] When executing the first SOC estimation logic, the control unit 130 can determine the estimated OCV of the battery cell BC based on the measured values ​​of the cell parameters (at least one of the cell voltage, the cell current, or the cell temperature) obtained from the sensing unit 110, and determine the SOC value associated with the estimated OCV among the SOC values ​​recorded in the first relationship data as the first estimated SOC.

[0137] The first SOC estimation logic may be prepared for the control unit 130 to estimate the SOC of the battery cell BC within the voltage plateau range (Z A ~Z B ), the estimated OCV is determined by subtracting a voltage value obtained by the internal resistance from a voltage value indicating the OCV of the battery cell BC (measured cell voltage).

[0138] When the estimated SOC of the battery cell BC is within the voltage platform range (Z A ~Z B ), the first SOC estimation logic may be prepared to determine that the first estimated SOC is equal to the estimated SOC of the battery cell BC by comparing the estimated SOC of the battery cell BC to the voltage platform range (Z A ~Z B ) and the SOC change corresponding to the current accumulation amount calculated at the same time are the same as the change immediately after the estimated SOC enters the voltage platform range (Z A ~Z B ) is a value obtained by adding the past estimated SOC calculated before.

[0139] In step S720, the control unit 130 determines a first estimated SOC based on the measured negative electrode resistance by executing the second SOC estimation logic. When executing the second SOC estimation logic, a series of processes may be performed to determine the SOC value associated with the measured negative electrode resistance collected in step 710 among the negative electrode resistance values ​​stored in the second relationship data as the second estimated SOC.

[0140] In step S730 , the control unit 130 determines an estimated SOC of a current cycle of the battery cell based on at least one of the first estimated SOC or the second estimated SOC.

[0141] The control unit 130 records the estimated SOC in the memory 140 each time step S730 is executed, and thus the memory 140 generates a change history (time series) of the estimated SOC. The estimated SOC of the current cycle determined in step S730 is again executed in the next cycle according to Figure 7 The method becomes the estimated SOC of the previous cycle.

[0142] Figure 8 It is schematically shown Figure 7 Flowchart of an example of a subroutine of step S730 in FIG.

[0143] refer to Figures 1 to 8 In step S810, the control unit 130 determines whether the first estimated SOC determined in step S710 is within the voltage plateau range (Z A ~Z B That is, in step S810, it is determined whether the first estimated SOC is less than the starting SOC (Z A ) or greater than the end SOC (Z B ). When the value of step S810 is “yes”, step S820 is executed. The value of step S810 is “no”, which means that the first estimated SOC is within the voltage platform range Z A ~Z B When the value of step S810 is "No", step S830 is executed.

[0144] In step S820 , the control unit 130 determines whether the estimated SOC of the current cycle of the battery cell BC is equal to the first estimated SOC.

[0145] In step S830 , the control unit 130 determines whether the estimated SOC of the current cycle of the battery cell BC is equal to the second estimated SOC.

[0146] Figure 9 It is schematically shown Figure 7 A flowchart of another example of a subroutine of step S730 in FIG. 1 , and Figure 10 Shows that in the implementation Figure 9 The method is an example of a weight map that can be used.

[0147] refer to Figures 1 to 7 、 Figure 9 and Figure 10 In step S910, the control unit 130 determines whether the first estimated SOC determined in step S610 is within the voltage plateau range (Z A ~Z B ). When the value of step S910 is "yes", step S920 is executed. When the value of step S910 is "no", step S940 is executed.

[0148] In step S920, the control unit 130 generates a voltage signal according to the voltage platform range (Z A ~Z B ) and the first estimated SOC to determine a first weight associated with the first estimated SOC and a second weight associated with the second estimated SOC.

[0149] When the first estimated SOC is less than the starting SOC (Z A ), the voltage platform range (Z A ~Z B ) and the first estimated SOC may be determined to be equal to the difference between the first estimated SOC and the starting SOC (Z A ) is the difference between .

[0150] When the first estimated SOC is greater than the termination SOC (Z B ), the voltage platform range (Z A ~Z B ) and the first estimated SOC may be determined to be equal to the difference between the first estimated SOC and the termination SOC (Z B ) is the difference between .

[0151] The first weight can be related to the voltage platform range (Z A ~Z B) has a predetermined positive correlation with the SOC difference between the first estimated SOC. The second weight may be related to the voltage platform range (Z A ~Z B ) has a predetermined negative correlation with the SOC difference between the first estimated SOC and the first estimated SOC. The sum of the first weight and the second weight may be a constant (e.g., 1), and thus, when either the first weight or the second weight is determined, the other weight may also be automatically determined. The first weight may be equal to or greater than the second weight.

[0152] Figure 10 A weight map 1000 recording the relationship between the first weight and the SOC difference is shown. The weight map 1000 may be stored in the memory 140 in advance.

[0153] The SOC difference close to 0 refers to the voltage platform range (Z A ~Z B ) of the first estimated SOC. On the contrary, close to the lower limit (Z A ) or upper limit (Z B ) refers to the SOC difference far away from the voltage platform range (Z A ~Z B )’s first estimated SOC.

[0154] When the first estimated SOC is less than the lower limit (Z A ) when the initial SOC (Z A ) can be set to Figure 10 The maximum value of the horizontal axis, and when the first estimated SOC is greater than the upper limit (Z B ) when SOC (Z B ) can be set to Figure 10 The maximum value of the horizontal axis.

[0155] In step S930 , the control unit 130 determines the estimated SOC of the current cycle of the battery cell BC to be equal to a weighted average of the first estimated SOC and the second estimated SOC based on the first weight and the second weight.

[0156] For example, when the first weight = 0.8, the second weight = 0.2, the first estimated SOC = 80%, and the second estimated SOC = 81%, the weighted average = (first estimated SOC × first weight) + (second estimated SOC × second weight) = (80% × 0.8) + (81% × 0.2) = 80.2%.

[0157] In step S940 , the control unit 130 determines the estimated SOC of the current cycle of the battery cell BC to be equal to a weighted average of the first and second estimated SOCs based on the third weight associated with the first estimated SOC and the fourth weight associated with the second estimated SOC.

[0158] In contrast to the first and second weights, the third and fourth weights may be pre-stored constants in memory 140. The fourth weight may be equal to or greater than the third weight, and the sum of the third and fourth weights may be equal to the sum of the first and second weights. For example, if the third weight = 0.3, the fourth weight = 0.7, the first estimated SOC = 60%, and the second estimated SOC = 61%, the weighted average = (first estimated SOC × third weight) + (second estimated SOC × fourth weight) = (60% × 0.3) + (61% × 0.7) = 18% + 42.7% = 60.7%. The third weight may be equal to or less than the minimum value that can be set as the first weight. The fourth weight may be equal to or greater than the maximum value that can be set as the second weight.

[0159] Figure 11 is schematically shown in Figure 7 A flowchart of another example of the subroutine of step S730, Figure 12 An example of a first correction coefficient map for correcting the first weight is shown, and Figure 13 An example of a second correction coefficient map for correcting the fourth weight is shown.

[0160] refer to Figures 1 to 7 as well as Figures 11 to 13 In step S1110, the control unit 130 determines whether the first estimated SOC determined in step S610 is within the voltage plateau range (Z A ~Z B ). When the value of step S1110 is "yes", step S1120 is executed. When the value of step S1110 is "no", step S1160 is executed.

[0161] In step S1120, the control unit 130 generates a voltage signal according to the voltage platform range (Z A ~Z B ) and the first estimated SOC to determine a first weight associated with the first estimated SOC and a second weight associated with the second estimated SOC.

[0162] In step S1130, the control unit 130 determines whether the estimated SOC is within the voltage plateau range (Z A ~Z B That is, determine the retention time outside the voltage platform range (Z A ~Z B ) from the latest time, it is estimated that the SOC has stayed in the voltage platform range (Z A ~Z B ) outside of the time.

[0163] In step S1140, the control unit 130 corrects the first weight and the second weight according to the retention time determined in step S1130. For example, after correcting either of the first weight and the second weight, the value of the other weight can be determined by subtracting the corrected weight from a predetermined constant (e.g., 1).

[0164] Figure 12 The first correction coefficient graph 1200 shown in FIG. 1 may be pre-stored in the memory 140 and used to correct the first weight.

[0165] According to the first correction coefficient map 1200, until the estimated SOC is within the voltage plateau range (Z A ~Z B ) reaches the predetermined reference time t R1 Previously, the correction coefficient of the first weight may have a positive correlation with the retention time. R1 Thereafter, the correction coefficient of the first weight may have a negative correlation with the retention time. The minimum value of the correction coefficient of the first weight is 1. The reference value L may be greater than 1 and may be a preset value to prevent an excessive increase in the corrected first weight.

[0166] Since in the voltage platform range (Z A ~Z B ) increases, the accumulation of current integration error occurs, resulting in a gradual decrease in the accuracy of the first estimated SOC determined by the first SOC estimation logic. R1 When the SOC of the battery cell BC is in the voltage platform range (Z A ~Z B ) leads to a decrease in the accuracy of SOC estimation due to excessive retention time.

[0167] In this regard, although Figure 12 shows that at the reference time t R1 The correction coefficient of the first weight before and after is linearly changed, but this should be simply understood as an example.

[0168] The corrected first weight may be equal to the product of the correction coefficient determined in the first correction coefficient map 1200 and the first weight. When the corrected first weight is determined, the control unit 130 may calculate the corrected second weight so that the sum of the corrected first weight and the corrected second weight is equal to a predetermined value (e.g., 1).

[0169] In step S1150, the control unit 130 determines the estimated SOC of the current cycle of the battery cell BC as a weighted average of the first estimated SOC and the second estimated SOC based on the corrected first weight and the corrected second weight. For example, when the corrected first weight = 0.81, the corrected second weight = 0.19, the first estimated SOC = 80%, and the second estimated SOC = 81%, the weighted average = (first estimated SOC × corrected first weight) + (second estimated SOC × corrected second weight) = (80% × 0.81) + (81% × 0.19) = 20.25% + 4.94% = 80.19%.

[0170] That is, the first estimated SOC and the second estimated SOC are the same as those in the above reference Figure 9 The described examples are equal, 80% and 81% respectively, but the corrected first weight determined based on the length of the retention time is greater than the original first weight, and the corrected secondary weight is less than the original second weight, so it can be seen that the SOC determined in step S1150 changes from 80.2% to 80.19%, which is closer to the first estimated SOC.

[0171] In step S1160, the control unit 130 determines whether the estimated SOC is within the voltage plateau range (Z A ~Z B ) retention time. That is, determine the time from the estimated SOC to the voltage platform range (Z A ~Z B ) from the latest time to estimate the SOC in the voltage platform range (Z A ~Z B ) within the time.

[0172] In step S1170 , the control unit 130 corrects the third weight and the fourth weight according to the retention time determined in step S1160 .

[0173] Figure 13 A second correction coefficient graph 1300 showing the relationship between the record correction coefficient and the retention time for correcting the fourth weight is shown. The second correction coefficient graph 1300 may be stored in the memory 140.

[0174] refer to Figure 13 , until the retention time reaches the predetermined reference time t R2 Previously, the correction factor could have a positive correlation with the retention time and be used when the retention time is equal to or greater than the reference time t R2 At the same time, the correction coefficient may be maintained as a reference value U. The reference value U may be greater than 1. The reference value U may be a preset value to prevent an excessive increase in the corrected fourth weight.

[0175] In this regard, although Figure 13 shows that at a time less than the reference time t R2 The linear change of the correction coefficient of the fourth weight within the time range of , but it should be simply understood as an example.

[0176] The corrected fourth weight may be equal to the product of the correction coefficient determined in the second correction coefficient map 1300 and the fourth weight. When the corrected fourth weight is determined, the control unit 130 may calculate the corrected third weight so that the sum of the corrected third weight and the corrected fourth weight is equal to a predetermined value (e.g., 1).

[0177] In step S1180, the control unit 130 determines the estimated SOC of the current cycle of the battery cell BC as a weighted average of the first estimated SOC and the second estimated SOC based on the corrected third weight and the corrected fourth weight. For example, when the corrected third weight = 0.25, the corrected fourth weight = 0.75, the first estimated SOC = 60%, and the second estimated SOC = 61%, the weighted average = (first estimated SOC × corrected third weight) + (second estimated SOC × corrected fourth weight) = 60.75%.

[0178] That is, the first estimated SOC and the second estimated SOC are Figure 9 The examples in are equal, 60% and 61% respectively, but the corrected third weight determined according to the retention time is smaller than the original third weight, and the corrected fourth weight is larger than the original fourth weight, so it can be seen that the SOC determined in step S1180 changes from 60.7% to closer to the second estimated SOC 60.75%.

[0179] Figure 14 is a flowchart exemplarily illustrating a battery management method according to a second embodiment of the present disclosure. Figure 7 The method determines the estimated SOC of the battery cell BC and then performs the following Figure 14 method.

[0180] refer to Figure 14 In step S1410 , the control unit 130 determines a first estimated SOH by executing a first SOH estimation logic.

[0181] In step S1420, the control unit 130 determines whether the battery cell BC is in a fully discharged state or a fully charged state. As an example, if the estimated SOC of the current cycle determined in step S730 is 0%, it indicates that the battery cell BC is in a fully discharged state. As another example, if the estimated SOC of the current cycle determined in step S730 is 100%, it indicates that the battery cell BC is in a fully charged state.

[0182] If the result of step S1420 is "yes", step S1430 is executed. If the result of step S1420 is "no", it means that the battery cell BC is neither in a fully discharged state nor in a fully charged state. If the result of step S1420 is "no", step S1440 is executed.

[0183] In step S1430 , the SOH of the battery cell BC is determined to be equal to the first estimated SOH.

[0184] In step S1440, the control unit 130 determines a second estimated SOH by executing the second SOH estimation logic. When the fully discharged state is determined in step S1420, the curve 510 is used to determine the second estimated SOH. Conversely, when the fully charged state is determined in step S1420, the curve 520 is used to determine the second estimated SOH.

[0185] In step S1450, the control unit 130 determines the current estimated SOH of the battery cell BC using the second estimated SOH or a weighted average of the first and second estimated SOH. The weighted average of the first and second estimated SOH may be equal to the sum of a value obtained by multiplying the first estimated SOH by a predetermined weight (fifth weight) and a value obtained by multiplying the second estimated SOH by a predetermined weight (sixth weight). The sum of the fifth and sixth weights may be a constant (e.g., 1). Each of the fifth and sixth weights may be preset.

[0186] The above-mentioned embodiments of the present disclosure are not only embodied by devices and methods, but can also be implemented by programs that execute functions corresponding to the exemplary configurations of the present disclosure or a recording medium on which the programs are recorded, and those skilled in the art can easily implement such implementation methods based on the disclosure of the aforementioned embodiments.

[0187] Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations may be made thereto within the technical aspects of the present disclosure and the scope of the appended claims and their equivalents.

[0188] In addition, those skilled in the art may make many substitutions, modifications and changes to the present disclosure as described above without departing from the technical aspects of the present disclosure. The present disclosure is not limited to the above embodiments and drawings, and some or all of the embodiments may be selectively combined to allow various modifications.

Claims

1. A battery management system comprising: a sensing unit configured to measure a cell voltage, a cell current, and a negative electrode resistance of a battery cell; as well as A control unit is configured to determine a state of the battery cell based on a measured value of each of the cell voltage, the cell current, and the negative electrode resistance.

2. The battery management system according to claim 1, in, The control unit is configured to: determining a first estimated SOC based on the measured values ​​of each of the cell voltage and the cell current by executing a first state of charge (SOC) estimation logic, determining a second estimated SOC based on the measured value of the negative electrode resistance by executing a second SOC estimation logic, and An estimated SOC of a current cycle of the battery cell is determined based on at least one of the first estimated SOC and the second estimated SOC.

3. The battery management system according to claim 2, in, The control unit is configured to determine the estimated SOC of the current cycle of the battery cell to be equal to either one of the first estimated SOC and the second estimated SOC or a weighted average of the first estimated SOC and the second estimated SOC based on a result of comparing the first estimated SOC with a voltage plateau range.

4. The battery management system according to claim 3, in, The control unit is configured to: The estimated SOC of the current cycle of the battery cell is determined to be equal to the first estimated SOC when the first estimated SOC is outside the voltage plateau range.

5. The battery management system according to claim 3, in, The control unit is configured to: The estimated SOC of the current cycle of the battery cell is determined to be equal to the second estimated SOC when the first estimated SOC is within the voltage plateau range.

6. The battery management system according to claim 3, in, The control unit is configured to: determining a first weight associated with the first SOC estimation logic and a second weight associated with the second SOC estimation logic according to a difference between the voltage plateau range and the first estimated SOC when the first estimated SOC is outside the voltage plateau range, and The estimated SOC of the current cycle of the battery cell is determined to be equal to a weighted average of the first estimated SOC and the second estimated SOC based on the first weight and the second weight.

7. The battery management system according to claim 6, in, The first weight has a predetermined positive correlation with a difference between the voltage plateau range and the first estimated SOC, and The second weight has a predetermined negative correlation with a difference between the voltage platform range and the first estimated SOC.

8. The battery management system according to claim 3, in, The control unit is configured to: The estimated SOC of the current cycle of the battery cell is determined to be equal to a weighted average of the first estimated SOC and the second estimated SOC based on a third weight and a fourth weight when the first estimated SOC is within the voltage plateau range.

9. The battery management system according to claim 3, in, The control unit is configured to: determining a first weight associated with the first SOC estimation logic and a second weight associated with the second SOC estimation logic according to a difference between the voltage plateau range and the first estimated SOC when the first estimated SOC is outside the voltage plateau range, Correcting the first weight and the second weight according to the retention time of the SOC within the voltage platform range, and The estimated SOC of the current cycle of the battery cell is determined to be equal to a weighted average of the first estimated SOC and the second estimated SOC based on a corrected first weight and a corrected second weight.

10. The battery management system according to claim 2, in, The control unit is configured to: When the estimated SOC of the current cycle indicates a fully discharged or fully charged state, a current estimated SOH of the battery cell is determined based on a measured value of each of the negative electrode resistance and a cell temperature of the battery cell.

11. A battery pack comprising the battery management system according to any one of claims 1 to 10.

12. An electric vehicle comprising the battery pack according to claim 11.

13. A battery management method comprising the following steps: Measure the cell voltage, cell current and negative electrode resistance of the battery cell; as well as The state of the battery cell is determined based on the measured value of each of the cell voltage, the cell current, and the negative electrode resistance.

14. The battery management method according to claim 13, in, The step of determining the electrical state of the battery cell comprises the following steps: determining a first estimated SOC based on the measured values ​​of each of the cell voltage and the cell current by executing first state of charge (SOC) estimation logic; determining a second estimated SOC based on the measured value of the negative electrode resistance by executing second SOC estimation logic; and An estimated SOC of a current cycle of the battery cell is determined based on at least one of the first estimated SOC and the second estimated SOC.

15. The battery management method according to claim 14, in, The step of determining the estimated SOC of the current cycle of the battery cell comprises the following steps: The estimated SOC of the current cycle of the battery cell is determined to be equal to either one of the first estimated SOC and the second estimated SOC or a weighted average of the first estimated SOC and the second estimated SOC according to a result of comparing the first estimated SOC with a voltage plateau range.

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