Apparatus and method for estimating battery SOC

Abstract

According to an embodiment of the present invention, there is provided a battery SOC estimating device including: a charging / discharging unit configured to receive a control signal including C-rate information, and charge / discharge the battery at a C-rate included in the control signal; a measuring unit configured to measure a voltage of the battery during a charging / discharging process of the battery; and a control unit configured to transmit the control signal to the charging / discharging unit, change the C-rate included in the control signal whenever a voltage value measured by the measuring unit reaches a preset threshold, and estimate the SOC of the battery based on a result of comparing the changed C-rate with a preset cutoff value.

Description

[Technical field]

[0001] This application claims priority to Korean Patent Application No. 10-2022-0011728 filed on January 26, 2022, the entire contents of which are incorporated herein by reference in their entirety in the specification and drawings.

[0002] The present invention relates to an apparatus and method for estimating the SOC of a battery, and more particularly to an apparatus and method for estimating the SOC of a battery. [Background technology]

[0003] In recent years, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has grown rapidly and the development of electric vehicles, energy storage batteries, robots, satellites, and other products has progressed in earnest, active research is being conducted into high-performance batteries that can be repeatedly charged and discharged.

[0004] Currently, commercially available secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium batteries. Of these, lithium batteries are attracting attention due to the advantages that they can be freely charged and discharged as they have almost no memory effect compared to nickel-based batteries, as well as an extremely low self-discharge rate and high energy density.

[0005] Generally, the SOC of a battery can be estimated by a current integration method that integrates the charge / discharge current amount, or from the open circuit voltage (OCV) measured in consideration of the correspondence between the SOC and the OCV. In addition, a method of estimating the SOC using an Extended Kalman Filter (EKF) of a battery model using the voltage behavior of the battery is also used.

[0006] Since the OCV can be measured in a resting state, the current integration method is mainly used in the charging and discharging process. However, the current integration method has a drawback in that the SOC estimation result is inaccurate if errors are accumulated during current integration or if the initial SOC value is inaccurate. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide an apparatus and method for estimating the SOC of a battery, which can estimate the SOC of a battery more accurately by changing the charge / discharge C-rate (C-Rate) and comparing the changed charge / discharge C-rate with a cutoff value.

[0008] Other objects and advantages of the present invention can be understood from the following description and become more apparent from the embodiments of the present invention. Also, the objects and advantages of the present invention can be realized by the means and combinations thereof as claimed in the claims. [Means for solving the problem]

[0009] According to one aspect of the present invention, a battery SOC estimating device may include a charging / discharging unit configured to receive a control signal including C-rate information, and charge / discharge the battery at a C-rate included in the control signal; a measuring unit configured to measure a voltage of the battery during a charging / discharging process of the battery; and a control unit configured to send the control signal to the charging / discharging unit, change the C-rate included in the control signal each time a voltage value measured by the measuring unit reaches a preset threshold, and estimate the SOC of the battery based on a result of comparing the changed C-rate with a preset cutoff value.

[0010] The controller may be configured to decrease the C-rate by a preset rate of change of the C-rate each time the measured voltage value reaches the preset threshold value.

[0011] The controller may be configured to estimate a SOC of the battery as a preset SOC if the modified C-rate is less than or equal to the cutoff value.

[0012] The controller may be configured to estimate the battery's SOC to be 100% if the modified C-rate is less than or equal to the cutoff value while the battery is being charged.

[0013] If the modified C-rate falls below the cutoff value while the battery is being discharged, the battery SOC may be configured to be estimated to be 0%.

[0014] The control unit may be configured to set a reference SOC for the battery at an initial change point when the C rate is first changed when the changed C rate exceeds the cutoff value, and estimate the SOC of the battery based on the reference SOC, the number of changes of the C rate after the initial change point, and an expected number of changes of the C rate expected until charging and discharging of the battery is completed during the charging and discharging process.

[0015] The control unit may be configured to estimate the SOC of the battery based on Equation 1 below when the changed C-rate exceeds the cutoff value.

number

[0016] The control unit may be configured to calculate the expected number of changes to the C rate based on the changed C rate, the cutoff value, and a preset change rate of the C rate.

[0017] The control unit may be configured to calculate the expected number of changes in the C rate based on Equation 2 below.

number

[0018] The measurement unit may be configured to further measure a current of the battery during the charging and discharging process.

[0019] The control unit may be configured to set the reference SOC by integrating a current of the battery measured by the measurement unit from a time point at which the charging / discharging starts to a time point at which the first change occurs.

[0020] The control unit may be configured to transmit a charge / discharge end signal to the charge / discharge unit to end charging / discharging of the battery when the changed C-rate is equal to or less than the cutoff value.

[0021] The control unit may be configured to transmit the control signal including the changed C-rate to the charging / discharging unit when the changed C-rate exceeds the cutoff value.

[0022] A battery pack according to another aspect of the present invention may include the battery SOC estimation device according to one embodiment of the present invention.

[0023] A method for estimating a SOC of a battery according to yet another aspect of the present invention may include a charging / discharging step of receiving a control signal including C-rate information, and charging / discharging a battery at a C-rate included in the control signal; a voltage measuring step of measuring a voltage of the battery during a charging / discharging process of the battery; a C-rate changing step of changing the C-rate included in the control signal every time a voltage value measured in the voltage measuring step reaches a preset threshold; and an SOC estimating step of estimating an SOC of the battery based on a result of comparing the C-rate changed in the C-rate changing step with a preset cutoff value. Effect of the Invention

[0024] According to one aspect of the present invention, the SOC of a battery can be estimated more accurately by charging and discharging the battery while changing the C-rate. In particular, the present invention has an advantage that the SOC of a battery can be estimated accurately even if the initial C-rate and temperature are not set to specific values.

[0025] The effects of the present invention are not limited to the above effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0026] The following drawings attached to this specification are intended to facilitate a further understanding of the technical ideas of the present invention together with the detailed description of the invention described below, and therefore the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief description of the drawings]

[0027] [Figure 1] 1 is a diagram illustrating a battery SOC estimation device according to an embodiment of the present invention; [Diagram 2] 1 is a diagram illustrating an embodiment of a battery SOC estimation device according to an embodiment of the present invention estimating a battery SOC. [Diagram 3]FIG. 2 is a schematic diagram illustrating an exemplary configuration of a battery pack according to another embodiment of the present invention. [Figure 4] FIG. 10 is a schematic diagram illustrating a method for estimating the SOC of a battery according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Prior to this, the terms and words used in the present specification and claims are not to be construed as being limited to their general and dictionary meanings, but are to be construed as being in accordance with the meanings and concepts of the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

[0029] Therefore, it should be understood that the embodiment described in this specification and the configurations shown in the drawings are merely the most preferred embodiment of the present invention and do not represent the entire technical idea of ​​the present invention, and therefore there may be various equivalents and modifications that can be substituted therefor at the time of this application.

[0030] Furthermore, in describing the present invention, if it is recognized that a specific description of related publicly known structures or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0031] Terms including ordinal numbers such as first, second, etc. are used to distinguish one of various components from the other components, and are not used to limit the components by these terms.

[0032] Throughout the specification, when a part is said to "comprise" a certain element, this means that it may further include other elements, not excluding other elements, unless otherwise specified.

[0033] Furthermore, throughout this specification, when a part is said to be "connected" to another part, this includes not only "directly connected" but also "indirectly connected" through another element between them.

[0034] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0035] FIG. 1 is a diagram illustrating a battery SOC estimation device 100 according to an embodiment of the present invention.

[0036] Referring to FIG. 1, a battery SOC estimating device 100 according to an embodiment of the present invention may include a charging / discharging unit 110, a measuring unit 120, and a control unit .

[0037] The charging / discharging unit 110 may be configured to receive a control signal including C-rate information (charge / discharge rate (Current rate) information).

[0038] For example, the charging / discharging unit 110 may be communicably connected to the control unit 130 via wire and / or wireless communication. The charging / discharging unit 110 may receive a control signal including C-rate information from the control unit 130.

[0039] Specifically, the initial value of the C-rate information included in the control signal may be set directly by the control unit 130 or may be set by a user's input depending on the battery specifications.

[0040] The charging / discharging unit 110 may be configured to charge / discharge the battery at the C rate included in the control signal.

[0041] Here, the term "battery" refers to a single independent cell that has a negative terminal and a positive terminal and can be physically separated. As an example, a lithium ion battery or a lithium polymer battery may be considered as a battery. The term "battery" may also refer to a battery module in which a plurality of cells are connected in series and / or parallel. In the following, for ease of explanation, the term "battery" will be described as meaning a single independent cell.

[0042] Specifically, the charge / discharge unit 110 can read the C-rate information included in the control signal and charge or discharge the battery at the corresponding C-rate.

[0043] For example, if the C rate is preset to 1C, the charge / discharge unit 110 may charge the battery at a C rate of 1C, or may discharge the battery at a C rate of 1C.

[0044] However, it should be noted that the value of the C rate information that can be included in the control signal is not particularly limited. The value of the C rate information may be set to 0.05C or more. Preferably, the value of the C rate information may be set to 0.05C or more and 3C or less.

[0045] The measurement unit 120 may be configured to measure the voltage of the battery during the charging and discharging process of the battery.

[0046] Specifically, the measurement unit 120 may be connected to the positive and negative terminals of the battery. The measurement unit 120 may measure the positive and negative voltages of the battery, respectively, and calculate the difference between the positive and negative voltages to measure the voltage of the battery. That is, the measurement unit 120 may measure the terminal voltage of the battery during the charging and discharging process of the battery.

[0047] The control unit 130 may be configured to transmit a control signal to the charging / discharging unit 110. As described above, the control unit 130 may generate a control signal including C-rate information and transmit the generated control signal to the charging / discharging unit 110.

[0048] The control unit 130 may be configured to change the C-rate included in the control signal every time the voltage value measured by the measurement unit 120 reaches a preset threshold value.

[0049] Here, the preset threshold value may be set for each of the charging process and the discharging process. Preferably, the preset threshold value may be a voltage value at which a constant voltage charge or a constant voltage discharge is started.

[0050] In general, the charging process may include a constant current (CC) charging process and a constant voltage (CV) charging process. For example, constant current charging may be performed until the battery voltage reaches 3.8V, and constant voltage charging may be performed after 3.8V. In this case, the threshold value may be preset to 3.8V, which is the voltage value at which constant voltage charging starts. Similarly, in the case of a discharging process, the voltage value at which constant voltage discharging starts may be set as the threshold value.

[0051] More specifically, the control unit 130 may be configured to decrease the C-rate at a preset rate of change of the C-rate each time the measured voltage value reaches a preset threshold value.

[0052] For example, in the process of charging a battery, assume that the threshold is set to 3.8V, the change rate of the C-rate is 0.5, and the initial C-rate is preset to 1C.

[0053] The charging / discharging unit 110 may receive a control signal including information about a C rate of 1C from the control unit 130 and charge the battery at 1C. When the voltage value measured by the measurement unit 120 reaches 3.8V, the control unit 130 may reduce the value of the C rate information included in the control information from 1C to 0.5C.

[0054] Then, the charging / discharging unit 110 may receive a control signal including information about a C rate of 0.5 C from the control unit 130 and reduce the C rate for the battery to 0.5 C. In this case, since the C rate has been reduced from 1 C to 0.5 C, the voltage value measured by the measurement unit 120 may decrease.

[0055] Specifically, the battery voltage is calculated based on the Ohms method, and the measured battery voltage may decrease because the C rate, which corresponds to "I" in the formula "V=IR", has decreased.

[0056] More specifically, in a normal constant voltage charging process, the charging current is gradually reduced so that the battery voltage remains at a constant level. However, in the present invention, the C-rate is abruptly changed according to the rate of change of the C-rate, so that the measured battery voltage may decrease.

[0057] Thereafter, the battery is charged at a C-rate of 0.5C, and when the battery voltage reaches 3.8V again, the control unit 130 may reduce the C-rate information included in the control signal to 0.25C.

[0058] FIG. 2 is a diagram illustrating an embodiment in which a battery SOC estimation device 100 according to an embodiment of the present invention estimates the SOC of a battery.

[0059] 2, charging of the battery may be started at time t0. Specifically, at time t0, the control unit 130 may send a control signal to the charging / discharging unit 110. The charging / discharging unit 110 may read the C-rate information included in the control signal and start charging the battery at the corresponding C-rate.

[0060] From time t0 to time t1 the battery may be charged at 1C.

[0061] At time t1, the battery voltage reaches the threshold V THIn this case, the control unit 130 may decrease the value of the C rate information included in the control signal according to the rate of change of the C rate. For example, the control unit 130 may decrease the value of the C rate information included in the control signal from 1C to 0.5C.

[0062] From time t1 to time t2 the battery may be charged at 0.5C.

[0063] At time t2, the battery voltage reaches the threshold V TH For example, the control unit 130 may decrease the value of the C rate information included in the control signal from 0.5C to 0.25C.

[0064] From time t2 to time t3 the battery may be charged at 0.25C.

[0065] At time t3, the battery voltage reaches the threshold V TH For example, the control unit 130 may decrease the value of the C rate information included in the control signal from 0.25C to 0.125C.

[0066] From time t3 to time t4 the battery may be charged at 0.125C.

[0067] At time t4, the battery voltage reaches the threshold V TH For example, the control unit 130 may decrease the value of the C rate information included in the control signal from 0.125C to 0.0625C.

[0068] From time t4 to time t5 the battery may be charged at 0.0625C.

[0069] At time t5, the battery voltage reaches the threshold V TH For example, the control unit 130 may decrease the value of the C rate information included in the control signal from 0.0625C to 0.03125C.

[0070] Then, at time t5, charging of the battery may be terminated.

[0071] The control unit 130 may be configured to estimate the SOC of the battery based on a result of comparing the modified C-rate with a preset cutoff value.

[0072] Here, the cutoff value may be a predetermined C-rate value, which may be a reference value for terminating the charging and discharging of the battery. For example, the cutoff value may be preset to 0.05C.

[0073] That is, the control unit 130 detects whether the voltage of the battery is equal to or lower than the threshold value V TH , the control unit 130 may change the C-rate value included in the control signal each time the cutoff value is reached, and compare the changed C-rate value with the cutoff value. Then, the control unit 130 may estimate the SOC of the battery based on the comparison result.

[0074] Specifically, when the changed C rate is equal to or less than the cutoff value, the control unit 130 may estimate the SOC of the battery as a preset SOC. Here, when the changed C rate is equal to or less than the cutoff value, this may correspond to a condition for terminating charging or discharging of the battery.

[0075] For example, if the changed C-rate falls below a cutoff value while the battery is being charged, the controller 130 may be configured to estimate the battery's SOC to be 100%. Conversely, if the changed C-rate falls below a cutoff value while the battery is being discharged, the controller 130 may be configured to estimate the battery's SOC to be 0%.

[0076] As in the above embodiment, in the embodiment of FIG. 2, if it is assumed that the battery starts to be charged at 1C at time t0, the cutoff value may be preset to 0.05C. At times t1, t2, t3, t4, and t5, the voltage value of the battery falls below the threshold V TH, and at time t5, the control unit 130 may change the C rate to 0.3125 C. Because the changed C rate (0.3125 C) is equal to or less than the cutoff value (0.05 C), the control unit 130 may estimate the SOC of the battery to be 100% at time t5.

[0077] In general, the current integration method used to estimate the SOC has a drawback in that if errors are accumulated during current integration or if the initial SOC value is not accurate, the SOC estimation result is inaccurate.

[0078] Therefore, in the present invention, the SOC of the battery can be estimated by taking into consideration the characteristic of the battery that the ultimate charge or discharge amount is the same under the same cut-off condition, and thus the estimation error of the SOC by the current integration method can be corrected and the SOC of the battery can be accurately estimated.

[0079] Here, the battery characteristics considered in the present invention are that even if the charge / discharge C rate and the temperature of the battery are different, the battery can be charged / discharged at a uniform amount under the same cut-off conditions. For example, when a predetermined cut-off value (e.g., 0.05C) is applied as in the present invention, the final charge or discharge amount can be the same even if the initial C rate and the temperature of the battery are different.

[0080] Therefore, the present invention has an advantage that the SOC of the battery can be accurately estimated based on the result of comparing the changed C-rate with the cutoff value.

[0081] Meanwhile, the control unit 130 provided in the battery SOC estimating device 100 may selectively include a processor, an application specific integrated circuit (ASIC), other chipsets, logic circuits, registers, a communication modem, a data processing device, etc., known in the art, for executing various control logics performed in the present invention. Also, when the control logic is realized by software, the control unit 130 may be realized by a collection of program modules. In this case, the program modules may be stored in a memory and may be executed by the control unit 130. The memory may be inside or outside the control unit 130, and may be connected to the control unit 130 by various known means.

[0082] The battery SOC estimation device 100 may further include a storage unit 140. The storage unit 140 may store data and programs required for each component of the battery SOC estimation device 100 to operate and function, or data generated in the process of operating and functioning. The storage unit 140 is not particularly limited in type as long as it is a known information storage means known to be capable of recording, erasing, updating, and reading data. As an example, the information storage means may include a random access memory (RAM), a flash memory, a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a register, and the like. The storage unit 140 may also store a program code in which a process that can be activated by the control unit 130 is defined.

[0083] The control unit 130 may be configured to transmit a control signal including the changed C rate to the charging / discharging unit 110 when the changed C rate exceeds the cutoff value. Conversely, the control unit 130 may be configured to transmit a charge / discharge end signal to the charging / discharging unit 110 to end charging / discharging of the battery when the changed C rate is equal to or less than the cutoff value.

[0084] Specifically, if the modified C-rate exceeds the cutoff value, the controller 130 may be configured to set the reference SOC for the battery at the time when the C-rate was first modified.

[0085] Here, the first change occurs when the battery voltage exceeds the threshold V TH This may be the point at which the first

[0086] For example, in the embodiment of FIG. 2, at time t1, the voltage value of the battery exceeds a threshold value V TH In order to reach this, the control unit 130 may change the C rate. Thus, in the embodiment of FIG. 2, time t1 may be the first time point of change.

[0087] More specifically, the reference SOC at the first change point may be set by a current integration method. To this end, the measurement unit 120 may be configured to further measure the current of the battery during the charging / discharging process. The control unit 130 may be configured to set the reference SOC by integrating the current of the battery measured by the measurement unit 120 from the start of charging / discharging to the first change point.

[0088] 2, the measurement unit 120 may measure the charging current of the battery from time t0 when charging of the battery starts to time t1, and may integrate the charging current from time t0 to time t1 to set the reference SOC at time t1 to 95%.

[0089] The control unit 130 may be configured to estimate the SOC of the battery based on the reference SOC, the number of changes in the C rate after the first change point, and the expected number of changes in the C rate expected until the charging / discharging of the battery is completed during the charging / discharging process.

[0090] Specifically, the control unit 130 may estimate the SOC during charging / discharging (when the changed C rate initializes the cutoff value) by taking into account the ratio of the number of times the C rate has been changed to the expected number of times of change and the reference SOC.

[0091] More specifically, the control unit 130 may be configured to estimate the SOC of the battery based on Equation 1 below.

number

[0092] For example, in the embodiment of Fig. 2, an embodiment in which the control unit 130 estimates the SOC of the battery at time t3 will be described. At time t3, the control unit 130 changes the C rate from 0.25 C to 0.125 C. At time t3, the number of times (m) the control unit 130 changes the C rate is two, excluding the first change time t1.

[0093] In addition, when the initial C rate (1C) is changed by a preset C rate change rate (0.5), the time when the changed C rate becomes equal to or less than the cutoff value is time t5, so the expected number of changes (n) of the C rate is 4, excluding the first change time t1. Here, the expected number of changes can be calculated by the control unit 130 using the initial C rate and the change rate, even if the charging and discharging of the battery is not completed.

[0094] In the embodiment of FIG. 2, the battery is charging so that the predetermined SOC value (T SOC ) is 100%, and the reference SOC (R SOC Therefore, the control unit 130 calculates "95 + {(100 - 95) ÷ 4 × 2}" based on the formula 1 to obtain the SOC (B SOC ) can be estimated to be 97.5%.

[0095] Therefore, the battery SOC estimating device 100 according to an embodiment of the present invention has an advantage in that it can estimate the SOC of the battery not only when charging / discharging of the battery is completed, but also when charging / discharging is being performed.

[0096] Meanwhile, referring to Equation 1, when the changed C rate becomes equal to or less than the cutoff value, the expected change number (n) and the C rate change number (m) may be the same. Then, the estimated SOC (B SOC ) is the predetermined SOC value (T SOC ) should be the same as Equation 1. Therefore, even if the charge / discharge is terminated (when the changed C rate is equal to or less than the cutoff value), the control unit 130 can estimate the predetermined SOC value and the SOC of the battery.

[0097] The control unit 130 may also be configured to calculate an expected number of changes to the C rate based on the changed C rate, the cutoff value, and a preset change rate of the C rate.

[0098] Specifically, the control unit 130 may be configured to calculate the expected number of changes in the C rate based on the following Equation 2.

[0099]

number

number

[0100] For example, in the embodiment of FIG. 2, the change rate (d) of the C rate may be 0.5, the initial C rate value (y) included in the control signal may be 1C, and the cutoff value may be 0.05C.

number

[0101] In other words, the battery SOC estimating device 100 according to an embodiment of the present invention has the advantage of being able to accurately estimate the SOC of a battery by taking into account the battery characteristic that the ultimate charge or discharge amount is the same even if the initial C rate and battery temperature are different when a predetermined cutoff value (e.g., 0.05C) is applied.

[0102] In addition, according to an embodiment of the present invention, since the SOC value calculated by the current integration method can be corrected by comparing the changed C-rate with the cutoff value, there is an advantage that the SOC can be accurately estimated even for an LFP battery in which a plateau appears in the SOC-OCV profile.

[0103] The battery SOC estimation device 100 according to the present invention may be applied to a battery management system (BMS). That is, the BMS according to the present invention may include the battery SOC estimation device 100 described above. In such a configuration, at least some of the components of the battery SOC estimation device 100 may be realized by complementing or adding functions of components included in a conventional BMS. For example, the charge / discharge unit 110, the measurement unit 120, the control unit 130, and the storage unit 140 of the battery SOC estimation device 100 may be realized as components of the BMS.

[0104] Furthermore, the battery SOC estimating device 100 according to the present invention may be provided in a battery pack 1. That is, the battery pack 1 according to the present invention may include the above-described battery SOC estimating device 100 and one or more battery cells. Furthermore, the battery pack 1 may further include electrical components (relays, fuses, etc.), a case, etc.

[0105] FIG. 3 is a diagram illustrating an exemplary configuration of a battery pack 1 according to another embodiment of the present invention.

[0106] Referring to FIG. 3, the positive pole of battery B may be connected to the positive terminal P+ of battery pack 1, and the negative pole of battery B may be connected to the negative terminal P− of battery pack 1.

[0107] The measurement unit 120 may be connected between the positive electrode of the battery B and the positive electrode terminal P+ of the battery pack 1 via a first sensing line SL1, and between the negative electrode of the battery B and the negative electrode terminal P- of the battery pack 1 via a second sensing line SL2. Thus, the measurement unit 120 may measure the voltage of the battery B via the first sensing line SL1 and the second sensing line SL2.

[0108] In addition, the measurement unit 120 may be connected to a current measuring element A disposed in a charge / discharge path (large current path) of the battery B via a third sensing line SL3 to measure the charge / discharge current of the battery B. Here, the current measuring element A may be an ammeter and / or a shunt resistor.

[0109] One end of the charging / discharging unit 110 may be connected between the positive electrode of the battery B and the positive terminal P+ of the battery pack 1, and the other end may be connected between the negative electrode of the battery B and the negative terminal P- of the battery pack 1. The charging / discharging unit 110 may charge / discharge the battery B based on C rate information included in a control signal received from the control unit 130.

[0110] FIG. 4 is a diagram illustrating a method for estimating the SOC of a battery according to still another embodiment of the present invention.

[0111] Preferably, each step of the battery SOC estimation method may be performed by the battery SOC estimation device 100. Please note that in the following, for ease of explanation, the contents overlapping with those described above will be briefly explained or omitted.

[0112] Referring to FIG. 4, the method for estimating the SOC of a battery may include a charging / discharging step (S100), a voltage measuring step (S200), a C-rate changing step (S300), and an SOC estimation step (S400).

[0113] The charging / discharging step (S100) is a step of receiving a control signal including C-rate information and charging / discharging the battery B at the C-rate included in the control signal, and may be performed by the charging / discharging unit 110.

[0114] For example, the charging / discharging unit 110 may receive a control signal including C-rate information from the control unit 130. Then, the charging / discharging unit 110 may read the C-rate information included in the control signal and charge or discharge the battery B at the corresponding C-rate.

[0115] The voltage measuring step (S200) is a step of measuring the voltage of battery B during the charging and discharging process of battery B, and may be performed by the measuring unit 120.

[0116] The C rate change step (S300) is a step of changing the voltage measured in the voltage measurement step (S200) to a preset threshold value V TH This step may be performed by the control unit 130 to change the C rate whenever the C rate reaches the

[0117] Specifically, the control unit 130 determines whether the measured voltage value is equal to or lower than a preset threshold value V TH Each time the C rate reaches a predetermined rate, the C rate may be changed by a preset C rate change rate.

[0118] For example, the control unit 130 may detect whether the measured voltage value is equal to or lower than a preset threshold value V TH Each time it reaches this, the C rate may be decreased by a factor of 0.5.

[0119] The SOC estimation step (S400) is a step of estimating the SOC of battery B based on the result of comparing the C rate changed in the C rate change step (S300) with a preset cutoff value, and can be performed by the control unit 130.

[0120] Specifically, if the changed C rate is equal to or less than the cutoff value, the control unit 130 may estimate the SOC of the battery B as a preset SOC. Then, the control unit 130 may be configured to transmit a charge / discharge end signal to the charging / discharging unit 110 to end the charging / discharging of the battery B.

[0121] Conversely, if the changed C rate exceeds the cutoff value, the control unit 130 may be configured to estimate the SOC of the battery B based on the above-described Equations 1 and 2. Then, the control unit 130 may be configured to transmit a control signal including the changed C rate to the charging / discharging unit 110.

[0122] The above-described embodiments of the present invention may be realized not only by an apparatus and a method, but also by a program for implementing functions corresponding to the configurations of the embodiments of the present invention or a recording medium having the program recorded thereon. Such implementation can be easily achieved by a person skilled in the technical field to which the present invention pertains, based on the description of the above-described embodiments.

[0123] Although the present invention has been described above using limited embodiments and drawings, the present invention is not limited thereto, and it goes without saying that various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains within the equivalent scope of the technical concept of the present invention and the scope of the claims.

[0124] Furthermore, the present invention described above may be variously replaced, modified, and altered by a person having ordinary knowledge in the technical field to which the present invention pertains, without departing from the technical spirit of the present invention. Therefore, the present invention is not limited to the above-described embodiments and the accompanying drawings, but may be configured by selectively combining all or part of each embodiment for various modifications. [Explanation of symbols]

[0125] 1 Battery Pack 100 Battery SOC Estimator 110 Charge / discharge section 120 Measuring section 130 Control section 140 Storage section

Claims

1. A charge / discharge unit configured to receive a control signal including C-rate information and charge / discharge the battery at the C-rate included in the control signal; A measurement unit configured to measure a voltage of the battery during a charging / discharging process of the battery; a control unit configured to transmit the control signal to the charge / discharge unit, change the C-rate included in the control signal each time the voltage value measured by the measurement unit reaches a preset threshold value, and estimate an SOC of the battery based on a result of comparing the changed C-rate with a preset cutoff value; A battery SOC estimation device comprising:

2. The control unit is The battery SOC estimating device according to claim 1 , configured to decrease the C-rate by a preset C-rate change rate each time the measured voltage value reaches the preset threshold.

3. The control unit is The battery SOC estimating device according to claim 1 , configured to estimate the SOC of the battery as a preset SOC if the modified C-rate is less than or equal to the cutoff value.

4. The control unit is configured to estimate a SOC of the battery as 100% if the modified C-rate falls below the cutoff value while the battery is being charged; 4. The battery SOC estimating device according to claim 3, configured to estimate the SOC of the battery to be 0% if the changed C-rate becomes equal to or less than the cutoff value while the battery is being discharged.

5. The control unit is 2. The battery SOC estimation device according to claim 1, configured to, when the changed C rate exceeds the cutoff value, set a reference SOC for the battery at a time point when the C rate was first changed, and estimate the SOC of the battery based on the reference SOC, the number of changes of the C rate after the time point when the C rate was first changed, and an expected number of changes of the C rate expected until charging and discharging of the battery is completed in the charging and discharging process.

6. The control unit is If the changed C-rate exceeds the cutoff value, the SOC of the battery is estimated based on the following Equation 1: [0010] Here, B ＳＯＣ is the estimated SOC of the battery, T ＳＯＣ is a SOC value that is predetermined according to the charge / discharge state of the battery, and R ＳＯＣ 6. The battery SOC estimating device according to claim 5, wherein n is the reference SOC, n is the expected number of changes in the C-rate, and m is the number of changes in the C-rate.

7. The control unit is The battery SOC estimating device according to claim 5 , configured to calculate the predicted number of changes in the C rate based on the changed C rate, the cutoff value, and a preset change rate of the C rate.

8. The control unit is The expected number of changes in the C rate is calculated based on the following formula 2: [0025] 8. The battery SOC estimating device of claim 7, wherein n is the expected number of changes in the C-rate, d is the rate of change of the C-rate, x is the cutoff value, and y is an initial C-rate value included in the control signal.

9. The measurement unit includes: The battery is further configured to measure a current of the battery during the charging and discharging process; The control unit is 6. The battery SOC estimating device according to claim 5, configured to set the reference SOC by integrating the current of the battery measured by the measurement unit from a time point when the charging / discharging starts to a time point when the first change occurs.

10. The control unit is When the changed C-rate is equal to or less than the cutoff value, a charge / discharge end signal for ending charging / discharging of the battery is transmitted to the charge / discharge unit; The battery SOC estimating device according to claim 1 , configured to transmit the control signal including the changed C-rate to the charge / discharge unit when the changed C-rate exceeds the cutoff value.

11. A battery pack comprising the battery SOC estimation device according to any one of claims 1 to 10.

12. receiving a control signal including C-rate information and charging / discharging the battery at the C-rate included in the control signal; a voltage measuring step of measuring a voltage of the battery during a charging / discharging process of the battery; a C-rate changing step of changing the C-rate included in the control signal every time the voltage value measured in the voltage measuring step reaches a preset threshold value; an SOC estimating step of estimating an SOC of the battery based on a result of comparing the C rate changed in the C rate changing step with a preset cutoff value; A method for estimating a battery SOC, comprising:

13. A program for causing a computer to function as the charge / discharge unit, the measurement unit, and the control unit included in the SOC estimation device described in any one of claims 1 to 10.

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