Battery management device and method

Abstract

A battery management device according to an embodiment of the present application includes: a battery information estimation unit configured to estimate battery information including OCV and SOC with respect to a battery cell based on at least one of a voltage and a current of the battery cell; a curve generation unit configured to receive the OCV and the SOC from the battery information estimation unit and generate an SOC curve including a correspondence between the OCV and the SOC; and a control unit configured to: receive the SOC curve from the curve generation unit; determine a turning point in the received SOC curve; and when there is at least one turning point in the SOC curve, set a correction interval in the SOC curve based on the OCV or the SOC corresponding to the turning point; and correct the SOC curve by linearizing the set correction interval.

Description

TECHNICAL FIELD

[0001] This application claims priority to Korean Patent Application No. 10-2020-0101933, filed on August 13, 2020, in the Republic of Korea, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a battery management device and method, and more particularly, to a battery management device and method capable of generating an SOC curve for a battery cell. BACKGROUND

[0003] Recently, there has been a sharp increase in demand for portable electronic products such as notebook computers, video cameras, and portable phones, and electric vehicles, energy storage batteries, robots, satellites, etc. are being developed vigorously. Accordingly, high-performance batteries that allow repeated charging and discharging are being actively researched.

[0004] Currently marketed batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, etc. Among them, lithium batteries are attracting attention because they have almost no memory effect compared to nickel-based batteries, and they also have very low self-charging rates and high energy densities.

[0005] A method of accurately estimating the state of charge (SOC) of a battery, which has an important influence on the performance of such a battery, is being researched (Non-Patent Literature 1). Methods for estimating the SOC of a battery can be roughly divided into a method using coulomb counting and a method using an extended Kalman filter (EKF).

[0006] Coulomb counting is a method of estimating the SOC of a battery by adding the SOC per hour to the initial SOC (SOC0) of the battery. Although coulomb counting is simple in terms of calculation, there is a disadvantage that errors are accumulated when the initial state of charge (SOC0) is not accurately known.

[0007] An extended Kalman filter is widely used to estimate the state of a nonlinear model. In the case of using an extended Kalman filter, the OCV (open circuit voltage) can be estimated using an equivalent circuit model (ECM) set for a battery, and the SOC of the battery can be estimated based on the estimated OCV. However, when using an extended Kalman filter, the internal parameters of the equivalent circuit model are converted by various environmental factors such as load current, SOC, and temperature, and this appears as an error caused by the model. Therefore, there is a need to develop a technology that more accurately estimates the SOC of a battery by correcting errors in the SOC estimated using an extended Kalman filter.

[0008] (Non-Patent Document 1) Compensation Method of EKF Based on LSTM for Estimating State of Charge of Li-polymer Battery, Transactions of KSAE (Korean Society of Agricultural Engineers), Beomjin Yoon, Seougyeol Yoo, Sangman Seong, Vol. 27, No. 7, pp. 501-507, July 2019. SUMMARY

[0009] Technical problem

[0010] The present disclosure aims to solve the problem of the SOC curve generated using an extended Kalman filter, and the present disclosure aims to provide a battery management device and method for generating an SOC curve having improved accuracy in estimating the SOC of a battery cell.

[0011] These and other objects and advantages of the present disclosure can be understood from the following detailed description, and will become more apparent from the exemplary embodiments of the present disclosure. Further, it will be easily understood that the objects and advantages of the present disclosure can be achieved by the means shown in the claims and combinations thereof.

[0012] Technical scheme

[0013] A battery management device according to one aspect of the present disclosure can include a battery information estimation unit configured to estimate battery information including an OCV and an SOC of a battery cell based on at least one of a voltage and a current of the battery cell; a curve generation unit configured to receive the OCV and the SOC from the battery information estimation unit and generate an SOC curve representing a correspondence between the OCV and the SOC; and a control unit configured to: receive the SOC curve from the curve generation unit; determine a point of inflection in the received SOC curve; when there is at least one point of inflection in the SOC curve, set a correction interval in the SOC curve based on the OCV or the SOC corresponding to the point of inflection; and correct the SOC curve by linearizing the set correction interval.

[0014] The control unit can be configured to remove the point of inflection included in the correction interval of the SOC curve by applying a linearization algorithm to the correction interval.

[0015] When there are a plurality of points of inflection in the SOC curve, the control unit can be configured to set a correction interval for each of the plurality of points of inflection and linearize the plurality of set correction intervals independently.

[0016] When at least two of the plurality of set correction intervals overlap, the control unit can be configured to set the plurality of overlapping correction intervals as one correction interval.

[0017] The control unit can be configured to correct the SOC curve a plurality of times while changing the size of the correction interval, calculate an SOC error for each of the plurality of corrected SOC curves based on the preset reference curve, select a target SOC curve having a minimum calculated SOC error among the plurality of corrected SOC curves, and set the selected target SOC curve as the standard curve of the battery cell.

[0018] The control unit can be configured to calculate an SOC error rate for each OCV for each of the plurality of corrected SOC curves by comparing the SOC for each OCV for the reference curve with the SOC for each OCV for the plurality of corrected SOC curves, and select a corrected SOC curve in which an error interval of the calculated SOC error rate for each OCV has a minimum size among the plurality of corrected SOC curves as a target SOC curve.

[0019] The control unit can be configured to select a SOC curve in which an error interval representing a difference between a minimum value and a maximum value of the calculated SOC error rate for each OCV for each of the plurality of corrected SOC curves has a minimum size as a target SOC curve.

[0020] The control unit can be configured to set a plurality of filter intervals based on the start point and the end point of the correction interval in the corrected SOC curve, respectively, and apply a filter algorithm to each of the plurality of set filter intervals.

[0021] The plurality of filter intervals can be configured to include a linear interval and a nonlinear interval based on the start point or the end point.

[0022] The control unit can be configured to correct each of the plurality of filter intervals by using the filter algorithm such that the linear interval and the nonlinear interval become a continuous interval.

[0023] The battery information estimation unit can be configured to estimate an OCV and an SOC corresponding to each other from a voltage and a current of the battery cell by using an equivalent circuit model and an extended Kalman filter.

[0024] A battery pack according to another aspect of the disclosure can include a battery management device according to one aspect of the disclosure.

[0025] A battery management method according to still another aspect of the present disclosure can include a battery information estimating step for estimating battery information including OCV and SOC of a battery cell based on at least one of voltage and current of the battery cell; a SOC curve generating step for generating a SOC curve representing a correspondence between the OCV and the SOC estimated in the battery information estimating step; an inflection point determining step for determining an inflection point in the SOC curve; a correction interval setting step for setting a correction interval in the SOC curve based on the OCV or the SOC corresponding to the inflection point when there is at least one inflection point in the SOC curve; and a SOC curve correcting step for correcting the SOC curve by linearizing the correction interval set in the correction interval setting step.

[0026] Beneficial effects

[0027] According to one aspect of the present disclosure, a battery management device according to embodiments of the present disclosure has the advantage of generating a more stable SOC curve by correcting an SOC curve of a battery cell generated based on an extended Kalman filter using a linearization algorithm.

[0028] In addition, according to one aspect of the present disclosure, when an inflection point is included in a generated SOC curve, a battery management device according to embodiments of the present disclosure can primarily correct the SOC curve by applying a linearization algorithm to a correction interval set to include the inflection point, and secondarily correct the SOC curve by applying a filtering algorithm to a partial interval of the primarily corrected SOC curve.

[0029] Effects of the present disclosure are not limited to the above-mentioned effects, and other unmentioned effects can be clearly understood from the description of the claims by those skilled in the art. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings illustrate preferred embodiments of the present disclosure and together with the foregoing disclosure, provide further understanding of the technical features of the present disclosure, and therefore, the present disclosure is not construed as being limited to the drawings.

[0031] Figure 1 FIG. 1 is a diagram schematically illustrating a battery management device according to embodiments of the present disclosure.

[0032] Figure 2 FIG. 2 is a diagram schematically illustrating an SOC curve generated by a battery management device according to embodiments of the present disclosure.

[0033] Figure 3 FIG. 3 is a diagram illustrating an example of an inflection point included in the SOC curve of FIG. 2. Figure 2

[0034] FIG. 4 is a diagram illustrating an example of an inflection point included in the SOC curve of FIG. 3.Figure 4 is a graph schematically showing an SOC curve to which a correction interval is set by the battery management device according to an embodiment of the present disclosure.

[0035] Figure 5 is a graph schematically showing an example of an SOC curve corrected by the battery management device according to an embodiment of the present disclosure. Figure 4

[0036] Figure 6 is a graph comparatively showing an SOC error rate of the SOC curve of Figure 2 and an SOC error rate of the corrected SOC curve of Figure 5

[0037] Figure 7 is a graph schematically showing an SOC curve to which a plurality of correction intervals are set by the battery management device according to an embodiment of the present disclosure.

[0038] Figure 8 is a graph schematically showing an example of an SOC curve corrected by the battery management device according to an embodiment of the present disclosure. Figure 7

[0039] Figure 9 is a graph schematically showing an SOC curve to which a plurality of filter intervals are set by the battery management device according to an embodiment of the present disclosure.

[0040] Figure 10 is an enlarged view showing a part of the SOC curve of Figure 9

[0041] Figure 11 is a graph schematically showing an exemplary configuration of a battery pack including the battery management device according to an embodiment of the present disclosure.

[0042] Figure 12 is a graph schematically showing a battery management method according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0043] It should be understood that the terms used in the present specification and the appended claims should not be construed as limited to general and dictionary meanings but interpreted in the context of the skilled in the art and based on the principles in allowing the application appropriately defines the terms for best explaining the idea. Accordingly, it should be understood that the embodiments described herein are merely exemplary and are not to be interpreted as limiting the scope of the disclosure.

[0044] Therefore, the description set forth herein is merely illustrative in nature and is not intended to limit the scope of the disclosure and, therefore, should be understood to be applicable to and adapted for use with other similarly purposed devices, structures, and methods, in the scope of the disclosure, without departing from the scope of the disclosure, and their equivalents. ​​​​

[0045] Additionally, in describing the present disclosure, detailed descriptions of related known elements or functions incorporated herein can be omitted when it is deemed that such an omission makes the key subject matter of the present disclosure unclear.

[0046] Terms including ordinal numbers such as "first," "second," etc. can be used to distinguish one element from another element in various elements, but are not intended to limit the elements by the terms.

[0047] Throughout the specification, when a part is referred to as "including" or "comprising" an arbitrary element, it means that the part can further include other elements, not excluding the other elements, unless otherwise specified.

[0048] In addition, the term "control unit" described in the specification refers to a unit processing at least one function or operation, and can be implemented by hardware, software, or a combination of hardware and software.

[0049] In addition, throughout the specification, when a part is referred to as "connected" to another part, it is not limited to the case where they are "directly connected", but also includes the case where they are "indirectly connected" with another element interposed therebetween.

[0050] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0051] Figure 1 is a diagram schematically illustrating a battery management apparatus 100 according to an embodiment of the present disclosure.

[0052] Referring to Figure 1 , the battery management apparatus 100 according to an embodiment of the present disclosure can include a battery information estimation unit 110, a curve generation unit 120, and a control unit 130.

[0053] The battery information estimation unit 110 can be configured to estimate battery information including OCV and SOC for the battery cell B based on at least one of voltage and current of the battery cell B.

[0054] Here, the battery cell B means one independent unit including a negative terminal and a positive terminal and physically separable. For example, one pouch-type lithium polymer cell can be considered as the battery cell B.

[0055] In addition, OCV means open-circuit voltage, and SOC means state of charge.

[0056] Specifically, the battery information estimation unit 110 can be configured to estimate the corresponding OCV and SOC of the battery cell B based on the voltage and current using an equivalent circuit model (ECM) and an extended Kalman filter (EKF). Since the method of estimating the battery's OCV and SOC based on the battery's voltage and current and the equivalent circuit model using an extended Kalman filter is a known method, its detailed description will be omitted.

[0057] The curve generation unit 120 can be configured to receive OCV and SOC from the battery information estimation unit 110.

[0058] Preferably, the curve generation unit 120 and the battery information estimation unit 110 can be connected to each other to achieve communication. When the battery information estimation unit 110 outputs the estimated OCV and SOC, the curve generation unit 120 can receive the OCV and SOC from the battery information estimation unit 110.

[0059] In addition, the curve generation unit 120 can be configured to generate a SOC curve representing the correspondence between OCV and SOC.

[0060] Specifically, the SOC curve can be a curve representing the correspondence between OCV and SOC estimated by the battery information estimation unit 110.

[0061] Figure 2 This is a schematic diagram illustrating the SOC curve P1 generated by the battery management device 100 according to an embodiment of the present disclosure.

[0062] For example, in Figure 2 In this implementation, the SOC curve P1 is an XY graph where SOC is set to X and OCV is set to Y. Furthermore, the entire range of SOC for the SOC curve P1 can be from 0% to 100%. That is, the SOC curve P1 is a planar graph showing the OCV and SOC in a one-to-one relationship.

[0063] The control unit 130 can be configured to receive the SOC curve P1 from the curve generation unit 120.

[0064] Preferably, the control unit 130 can be communicatively connected to the curve generation unit 120. Furthermore, when the curve generation unit 120 outputs the generated SOC curve P1, the control unit 130 can receive the SOC curve P1 from the curve generation unit 120.

[0065] Additionally, the control unit 130 can be configured to determine the inflection point in the received SOC curve P1.

[0066] Here, the inflection point means a point at which a graph changes from an upper convex state to a lower convex state or from a lower convex state to an upper convex state in a twice differentiable function. In general, in a flat curve, a point at which a curvature changes from positive to negative or from negative to positive is referred to as an inflection point.

[0067] For example, the control unit 130 can set the SOC curve P1 representing the correspondence between the OCV and the SOC as an f(x) function, and perform a second differentiation on the f(x) function to obtain a second derivative f"(x) of the SOC curve P1. Here, it is assumed that the function f(x) is continuous and can be twice differentiated. In addition, the control unit 130 can determine a point at which a sign of f"(x) changes from positive to negative or from negative to positive based on f"(SOC) = 0 as an inflection point in the second derivative f"(x).

[0068] Figure 3 is a graph schematically showing an example of an inflection point included in the SOC curve P1 of Figure 2 .

[0069] Hereinafter, for convenience of description, it is assumed that only the first inflection point IP1, the second inflection point IP2, and the third inflection point IP3 are included in the SOC curve P1 as shown in Figure 3 . Here, the SOC of the first inflection point IP1 can be 10%, the SOC of the second inflection point IP2 can be 55%, and the SOC of the third inflection point IP3 can be 95%.

[0070] When at least one inflection point is present in the SOC curve P1, the control unit 130 can be configured to set a correction interval in the SOC curve P1 based on an OCV or an SOC corresponding to the inflection point.

[0071] For example, the control unit 130 can set the correction interval based on the SOC.

[0072] In detail, the control unit 130 can set the correction interval in the SOC curve P1 only when it is determined that the inflection point is present in the SOC curve P1. If the inflection point is not present in the SOC curve P1, the control unit 130 does not set the correction interval in the SOC curve P1, and sets the SOC curve P1 received from the curve generation unit 120 as a standard curve of the corresponding battery cell B.

[0073] More specifically, the control unit 130 can set the correction interval to include the inflection point. That is, the correction interval set by the control unit 130 can always include the inflection point.

[0074] Figure 4 is a graph schematically showing the SOC curve P1 in which the correction interval C is set by the battery management apparatus 100 according to the embodiment of the disclosure.

[0075] For example, in Figure 4 In this implementation, the control unit 130 can set the correction interval C based on the State of Charge (SOC) to include all inflection points of the first inflection point IP1, the second inflection point IP2, and the third inflection point IP3. Here, the correction interval C can be a SOC range from 3% to 100%.

[0076] In addition, the control unit 130 can be configured to correct the SOC curve P1 by linearizing the set correction interval C.

[0077] Referring to the definition of the inflection point described above, the inflection point may occur in the nonlinear region of the SOC curve P1. Therefore, the control unit 130 can correct the SOC curve P1 by linearizing the nonlinear region that includes the inflection point.

[0078] In other words, the control unit 130 can be configured to remove inflection points in the correction interval C of the SOC curve P1 by applying a linearization algorithm to the correction interval C.

[0079] Here, as a linearization algorithm, an algorithm that can convert the nonlinear interval of the curve into a linear interval can be applied. For example, regression analysis methods such as least squares (LSM), least squares approximation (LSA), and least mean squares (LMSM) can be applied as linearization algorithms.

[0080] Figure 5 This schematically illustrates the calibration of a battery management device 100 according to an embodiment of the present disclosure. Figure 4 A graph showing an example of the SOC curve P1.

[0081] Specifically, Figure 5 The SOC curve P2 is obtained by linearizing the correction interval C using the least squares method by the control unit 130. Since the correction interval C, including inflection points, is linearized, the corrected SOC curve P2 may not include inflection points. Figure 5 In this context, Q refers to the linearization correction interval C.

[0082] In the following text, reference will be made to Figure 6 The SOC error rate of the SOC curve P2 after the inflection point has been removed by the control unit 130 is described, as well as the SOC error rate of the SOC curve P1 including the inflection point.

[0083] Figure 6 It is shown in comparison Figure 2 The SOC error rate of the SOC curve P1 and Figure 5 The graph shows the SOC error rate of the corrected SOC curve P2.

[0084] The SOC error rate means a difference between a preset reference curve and an SOC curve of the battery cell B for each OCV. Here, the reference curve can be a preset curve to represent a correspondence between the OCV and the SOC of the battery cell B. For example, the reference curve can be a curve representing a correspondence between the OCV and the SOC of the battery cell B estimated according to a method different from the extended Kalman filter (e.g., coulomb counting).

[0085] For example, for each OCV, the SOC error rate can be calculated according to a formula of "(SOC of the SOC curve - SOC of the reference curve) ÷ SOC of the reference curve x 100". According to the above formula, the unit of the SOC error rate can be expressed as [%].

[0086] In an embodiment of the SOC curve P2, Figure 6 In an embodiment of the SOC curve P2,

[0087] Referring to Figure 6 The SOC error rate of the corrected SOC curve P2, from which the inflection point is removed by the control unit 130, can have a small variation compared to the SOC error rate of the SOC curve P1 including the inflection point. Specifically, the size of the error interval (Perr) of the SOC curve P1 can be greater than the size of the error interval (Qerr) of the corrected SOC curve P2.

[0088] Since the SOC error rate can occur uniformly as the size of the error interval is smaller for the total OCV interval, the SOC curve P2 corrected by the control unit 130 can be regarded as a curve more suitable for the battery cell B compared to the SOC curve P1 generated by the curve generation unit 120. That is, the SOC curve P2 corrected by the control unit 130 can be a more stable curve than the SOC curve P1 generated by the curve generation unit 120.

[0089] For example, when the battery information estimation unit 110 estimates the SOC of the battery cell B using the extended Kalman filter, noise can affect the Kalman gain near the inflection point included in the SOC curve P1. Accordingly, the size of the error interval (Perr) of the SOC curve P1 generated by the curve generation unit 120 can be greater than the size of the error interval (Qerr) of the SOC curve P2 corrected by the control unit 130. That is, the SOC curve P1 generated by the curve generation unit 120 can not be more stable than the SOC curve P2 corrected by the control unit 130 due to the influence of noise.

[0090] Accordingly, the battery management device 100 according to the embodiment of the disclosure has the following advantage: a more stable SOC curve P1 is generated by correcting the SOC curve P1 generated based on the extended Kalman filter of the battery cell B using a linearization algorithm.

[0091] Meanwhile, the control unit 130 provided to the battery management device 100 according to the embodiment of the disclosure can selectively include a processor, an application specific integrated circuit (ASIC), other chip sets, logic circuits, registers, communication modems, data processing devices, etc. known in the art to perform various control logics performed in the disclosure. Furthermore, when the control logics are implemented in software, the control unit 130 can be implemented as a set of program modules. At this time, the program modules can be stored in a memory and executed by the control unit 130. The memory can be located inside or outside the control unit 130, and can be connected to the control unit 130 by various well-known means.

[0092] In addition, the battery management device 100 according to the embodiment of the disclosure can further include a storage unit 140. The storage unit 140 can store data necessary for the operation and functions of each component of the battery management device 100, data generated in the process of performing the operation or function, etc. The storage unit 140 is not particularly limited in terms of its kind, as long as it is a known information storage device that can record, erase, update, and read data. As an example, the information storage device can include a RAM, a flash memory, a ROM, an EEPROM, a register, etc. In addition, the storage unit 140 can store program codes in which processes executable by the control unit 130 are defined.

[0093] For example, the storage unit 140 can store voltage information and current information of the battery cell B. In addition, the storage unit 140 can store parameters and functions related to the equivalent circuit model and the extended Kalman filter preset to correspond to the battery cell B.

[0094] When there are a plurality of inflection points in the SOC curve P1, the control unit 130 can be configured to set a correction interval for each of the plurality of inflection points IP1, IP2, IP3.

[0095] For example, in the embodiment of Figure 4 , the control unit 130 sets a correction interval C including all of the first inflection point IP1, the second inflection point IP2, and the third inflection point IP3. Alternatively, the control unit 130 can set a correction interval for each of the first inflection point IP1, the second inflection point IP2, and the third inflection point IP3.

[0096] Figure 7is a graph schematically showing an SOC curve P1 corrected by the battery management device 100 according to the embodiment of the present disclosure.

[0097] For example, in the embodiment of the present disclosure, the control unit 130 can set a first correction interval C1 for the first inflection point IP1, a second correction interval C2 for the second inflection point IP2, and a third correction interval C3 for the third inflection point IP3. Here, the first correction interval C1 can be an SOC interval of 5% to 15%, the second correction interval C2 can be an SOC interval of 50% to 60%, and the third correction interval C3 can be an SOC interval of 90% to 100%. Figure 7

[0098] In addition, the control unit 130 can be configured to linearize each of the plurality of set correction intervals C1, C2, C3 independently.

[0099] Specifically, when the SOC curve P1 is corrected by linearizing each of the plurality of correction intervals C1, C2, C3, the control unit 130 can set the correction intervals C1, C2, C3 so that there is no inflection point in the corrected SOC curve P3.

[0100] For example, when all of the inflection points included in the SOC curve P1 are not completely removed by only the plurality of correction intervals C1, C2, C3, the control unit 130 can set one correction interval including all of the inflection points IP1, IP2, IP3 as in the embodiment of the present disclosure. Figure 3

[0101] Figure 8 is a graph schematically showing an example of the SOC curve P1 corrected by the battery management device 100 according to the embodiment of the present disclosure. Figure 7

[0102] The control unit 130 can linearize each of the first correction interval C1, the second correction interval C2, and the third correction interval C3. In the embodiment of the present disclosure, Q1 means the linearized first correction interval C1, Q2 means the linearized second correction interval C2, and Q3 means the linearized third correction interval C3. Accordingly, the first inflection point IP1, the second inflection point IP2, and the third inflection point IP3 can be removed from the corrected SOC curve P3 of the embodiment of the present disclosure. That is, there can be no inflection point in the corrected SOC curve P3. Figure 8 Figure 8

[0103] In addition, in the embodiment of the present disclosure, the control unit 130 can set the first correction interval C1, the second correction interval C2, and the third correction interval C3 so that the first inflection point IP1, the second inflection point IP2, and the third inflection point IP3 are removed from the SOC curve P1. Figure 7 Figure 8 ​​​​​​In the implementation of the method, even if the first inflection point IP1, the second inflection point IP2 and the third inflection point IP3 are set as the midpoints of the first correction interval C1, the second correction interval C2 and the third correction interval C3 respectively, in some cases, the midpoint of each of the first correction interval C1, the second correction interval C2 and the third correction interval C3 may not be set as the first inflection point IP1, the second inflection point IP2 and the third inflection point IP3.

[0104] Furthermore, although the interval sizes of the first correction interval C1, the second correction interval C2, and the third correction interval C3 are all set to the same 10% SOC, the interval sizes of the first correction interval C1, the second correction interval C2, and the third correction interval C3 can also be set differently to remove multiple inflection points IP1, IP2, and IP3 included in the SOC curve P1.

[0105] According to embodiments of this disclosure, the battery management device 100 can improve the SOC estimation accuracy of battery cell B by setting correction intervals C1, C2, C3 for each of a plurality of inflection points IP1, IP2, IP3 and linearizing each of the plurality of set correction intervals C1, C2, C3 independently through the corrected SOC curve P3.

[0106] When at least two of the multiple set correction intervals C1, C2, C3 overlap, the control unit 130 can be configured to set the multiple overlapping correction intervals C1, C2, C3 as a single correction interval.

[0107] and Figure 7 The implementation methods differ, assuming that the first correction interval C1 and the second correction interval C2 overlap. For example, assume that the first correction interval C1 is set to a SOC range of 5% to 35%, and the second correction interval C2 is set to a SOC range of 30% to 60%. In this case, the first correction interval C1 and the second correction interval C2 can overlap in the 30% to 35% SOC range. In this case, when the control unit 130 linearizes the first correction interval C1 and the second correction interval C2 respectively, the linearized first correction interval C1 and the linearized second correction interval C2 can coexist in the 30% to 35% SOC range. Therefore, the control unit 130 can integrate the first correction interval C1 and the second correction interval C2 to set the 5% to 60% SOC range as a single correction interval.

[0108] The control unit 130 can be configured to calibrate the SOC curve P1 multiple times while changing the size of the calibration interval.

[0109] For example, the control unit 130 can generate a plurality of corrected SOC curves by reducing the size of the plurality of correction intervals C1, C2, C3 by 1% SOC. In this case, Figure 8 The corrected SOC curve P3 can be any one of the plurality of corrected SOC curves.

[0110] Preferably, the plurality of corrected SOC curves generated by the control unit 130 can be stored in the storage unit 140.

[0111] In addition, the control unit 130 can be configured to calculate an SOC error for each of the plurality of corrected SOC curves generated based on the preset reference curve.

[0112] For example, it is assumed that 10 SOC curves corrected by the control unit 130 are generated. The control unit 130 can calculate an SOC error rate for each of the 10 corrected SOC curves.

[0113] Specifically, the control unit 130 can be configured to calculate an SOC error rate for each OCV for each of the plurality of corrected SOC curves by comparing the SOC for each OCV for the reference curve with the SOC for each OCV for each of the plurality of corrected SOC curves.

[0114] In addition, the control unit 130 can be configured to select a target SOC curve having a minimum calculated SOC error rate from among the plurality of corrected SOC curves.

[0115] Here, the minimum SOC error rate means minimizing the size of the error interval of the SOC error rate calculated for each OCV in the plurality of corrected SOC curves.

[0116] For example, when Figure 8 The corrected SOC curve P3 is an SOC curve in which the error interval of the SOC error rate calculated for each OCV in the plurality of corrected SOC curves has the smallest size, the control unit 130 can be configured to select the corrected SOC curve P3 as the target SOC curve.

[0117] Specifically, the control unit 130 can be configured to select the corrected SOC curve P3 in which the error interval representing the difference between the minimum value and the maximum value of the SOC error rate for each OCV calculated for each of the plurality of corrected SOC curves has the smallest size as the target SOC curve.

[0118] In addition, the control unit 130 can be configured to set the selected target SOC curve as a standard curve of the battery cell B.

[0119] That is, by setting the target SOC curve having the smallest size of error interval among the plurality of corrected SOC curves as the standard curve of the battery cell B, the battery management device 100 can improve the accuracy, stability, and reliability of the estimation of the SOC of the battery cell B and the secondary battery of the same type as the battery cell B based on the set standard curve.

[0120] The control unit 130 can be configured to set a plurality of filter intervals based on each of the start point and the end point of the correction interval in the corrected SOC curve P2, P3.

[0121] Here, the start point of the correction interval means the lowest SOC of the correction interval, and the end point of the correction interval means the highest SOC of the correction interval. For example, in the embodiment of FIG. 10, Figure 8 In the embodiment of FIG. 10, the start point of the first correction interval C1 is the SOC of 5%, and the end point is the SOC of 15%. The start point of the second correction interval C2 is the SOC of 50%, and the end point is the SOC of 60%. The start point of the third correction interval C3 is the SOC of 90%, and the end point is the SOC of 100%.

[0122] Figure 9 FIG. 11 is a graph schematically showing the SOC curve P3 in which a plurality of filter intervals are set by the battery management device 100 according to the embodiment of the disclosure.

[0123] In the embodiment of FIG. 11, Figure 9 In the embodiment of FIG. 11, the control unit 130 can set the first filter interval F1, the second filter interval F2, the third filter interval F3, the fourth filter interval F4, and the fifth filter interval F5. In the embodiment of FIG. 11, Figure 9 In the embodiment of FIG. 11, since the end point of the third correction interval C3 is the SOC of 100%, the control unit 130 can not separately set the sixth filter interval F6 corresponding to the end point of the third correction interval C3.

[0124] In addition, the control unit 130 can be configured to apply a filter algorithm to each of the plurality of set filter intervals.

[0125] Here, the filter algorithm can be a smoothing algorithm that can remove noise included in the correction interval. As the filter algorithm, various algorithms can be applied, and for example, Gaussian smoothing or a low-pass filter can be applied.

[0126] Specifically, the plurality of filter intervals F1, F2, F3, F4, F5 can be configured to include a linear interval and a nonlinear interval based on the start point or the end point. Here, the nonlinear interval can be an interval present according to the SOC curve P1 generated by the curve generation unit 120, and the linear interval can be the intervals Q, Q1, Q2, Q3 linearized by the control unit 130. This will be described with reference to FIGS. 12 to 14. Figure 10The non-linear region and the linear region are described in detail.

[0127] Figure 10 is an enlarged view of a portion of the SOC curve P3 of Figure 9 . Specifically, Figure 10 is an enlarged view of a portion of the SOC curve P3 of Figure 9 near the second correction region C2.

[0128] Referring to Figure 10 , the third filter region F3 and the fourth filter region F4 can include the non-linear region R_nl and the linear region R_l. For example, in an embodiment of Figure 10 , the linear region R_1 can mean the linearized second correction region C2. That is, since the filter region includes the start point or the end point of the correction region, both the non-linear region R_nl and the linear region R_l can be included in the filter region.

[0129] In addition, the control unit 130 can be configured to correct each of the plurality of filter regions F1, F2, F3, F4, F5 using a filter algorithm such that the linear region R_1 and the non-linear region R_nl become continuous regions.

[0130] For example, it is assumed that a least square method is used as the linearization algorithm. When the control unit 130 linearizes the second correction region C2 using the least square method, the linear region R_1 and the non-linear region R_nl included in the second correction region C2 can not be continuous with each other. That is, the linear region R_l can be discontinuous with the non-linear region R_nl because the least square method is a regression analysis method for approximately deriving an equation that minimizes the sum of squares of residuals of a plurality of data.

[0131] Therefore, the control unit 130 can correct the SOC curve P3 by setting the filter regions F3, F4 for each of the start point and the end point of the correction region C2 and applying a filter algorithm to each of the set filter regions F3, F4 such that the non-linear region R_nl and the linear region R_1 become continuous regions.

[0132] That is, if the generated SOC curve P1 includes an inflection point, the battery management device 100 according to the embodiment of the present disclosure can primary correct the SOC curve P1 by applying a linearization algorithm to a correction interval set to include the inflection point, and secondary correct the SOC curve P3 by applying a filter algorithm to a partial interval (filter interval) of the primary corrected SOC curve P3. That is, the SOC curve P3 corrected by the battery management device 100 can more accurately represent the correspondence between the OCV and the SOC of the battery cell B than the SOC curve P1 generated using the extended Kalman filter. Accordingly, according to the SOC curve P3 corrected by the battery management device 100, the accuracy and reliability of the SOC estimation of the battery cell B can be improved.

[0133] The battery management device 100 according to the present disclosure can be applied to a BMS (Battery Management System). That is, the BMS according to the present disclosure can include the battery management device 100 described above. In this configuration, at least some components of the battery management device 100 can be implemented by supplementing or adding the functions of components included in a conventional BMS. For example, the battery information estimation unit 110, the curve generation unit 120, the control unit 130, and the storage unit 140 of the battery management device 100 can be implemented as components of the BMS. In addition, the BMS can estimate the SOC of the battery cell B using the SOC curve corrected by the control unit 130.

[0134] In addition, the battery management device 100 according to the present disclosure can be provided to the battery pack 1. That is, the battery pack 1 according to the present disclosure can include the battery management device 100 described above and at least one battery cell B. In addition, the battery pack 1 can further include electrical devices (relays, fuses, etc.) and a housing.

[0135] Figure 11 FIG. 1 is a diagram schematically illustrating an exemplary configuration of a battery pack 1 including a battery management device 100 according to an embodiment of the present disclosure.

[0136] Referring to Figure 11 , the battery pack 1 can include a battery cell B, a measurement unit 200, and the battery management device 100.

[0137] The measurement unit 200 can be configured to measure the voltage and the current of the battery cell B. For example, in an embodiment of the present disclosure, the measurement unit 200 can measure the voltage of the battery through first and second sense lines SL1 and SL2. In addition, the measurement unit 200 can measure the current of the battery through a third sense line SL3 connected to a current measurement unit A. Figure 11

[0138] ​In addition, the measurement unit 200 can be connected to communicate with the battery information estimation unit 110 of the battery management device 100. Accordingly, when the measurement unit 200 outputs the measured voltage information and current information of the battery cell B, the battery information estimation unit 110 can receive the voltage information and current information of the battery cell B from the measurement unit 200.

[0139] In addition, a load capable of charging or discharging the battery cell B can be further connected to the positive terminal (P+) and the negative terminal (P-) of the battery pack 1.

[0140] In addition, the battery management device 100 according to the disclosure can be included in a battery manufacturing system. Here, the battery manufacturing system can mean a system that can be applied to a process of producing, assembling, and inspecting the battery cell B.

[0141] The battery management device 100 can be used to obtain the corrected SOC curve P2, P3 of the produced battery cell B in the process of inspecting the battery cell B. That is, the SOC curve P2, P3 corrected by the battery management device 100 can be set as a standard curve of the corresponding battery cell B. Thereafter, the SOC of the corresponding battery cell B can be estimated based on the standard curve set by the battery management device 100.

[0142] Figure 12 FIG. 1 is a diagram schematically illustrating a battery management method according to an embodiment of the disclosure.

[0143] Each step of the battery management method can be performed by the battery management device 100. Hereinafter, it should be noted that, for convenience of description, overlapping content with the previously described content will be briefly described or omitted.

[0144] Referring to Figure 12 , the battery management method can include a battery information estimation step (S100), an SOC curve generation step (S200), an inflection point determination step (S300), a correction interval setting step (S400), and an SOC curve correction step (S500).

[0145] The battery information estimation step (S100) is a step of estimating battery information including OCV and SOC of the battery cell B based on at least one of voltage and current of the battery cell B, and can be performed by the battery information estimation unit 110.

[0146] For example, the battery information estimation unit 110 can estimate the OCV and SOC of the battery cell B using the voltage and current of the battery cell B and a pre-set equivalent circuit model and an extended Kalman filter.

[0147] The SOC curve generation step (S200) is a step of generating the SOC curve P1 indicating a correspondence between the OCV estimated in the battery information estimation step (S100) and the SOC, and can be executed by the curve generation unit 120.

[0148] For example, in an embodiment of the present technology, Figure 2 The curve generation unit 120 can generate the SOC curve P1.

[0149] The inflection point determination step (S300) is a step of determining the inflection points in the SOC curve P1, and can be executed by the control unit 130.

[0150] For example, in an embodiment of the present technology, Figure 3 The control unit 130 can determine the first inflection point IP1, the second inflection point IP2, and the third inflection point IP3 in the SOC curve P1.

[0151] The correction interval setting step (S400) and the SOC curve correction step (S500) can be executed when there is at least one inflection point in the SOC curve P1. If there is no inflection point in the SOC curve P1 generated in the SOC curve generation step (S200), the correction interval setting step (S400) and the SOC curve correction step (S500) can not be executed.

[0152] Specifically, the correction interval setting step (S400) is a step of setting the correction interval C in the SOC curve P1 based on the OCV or the SOC corresponding to the inflection point, and can be executed by the control unit 130.

[0153] For example, in an embodiment of the present technology, Figure 4 The control unit 130 can set the correction interval C to include the inflection points IP1, IP2, IP3 of the SOC curve P1. Specifically, when the correction interval is corrected in the SOC curve correction step (S500), the control unit 130 can set the correction interval so that there is no inflection point in the corrected SOC curve.

[0154] The SOC curve correction step (S500) is a step of correcting the SOC curve P1 by linearizing the correction interval set in the correction interval setting step (S400), and can be executed by the control unit 130.

[0155] For example, in an embodiment of the present technology, Figure 5In an embodiment of the present disclosure, the control unit 130 can remove the inflection points IP1, IP2, IP3 included in the correction interval C by linearizing the correction interval C. Accordingly, since there are no inflection points in the corrected SOC curve P2, the SOC error rate of the corrected SOC curve P2 can be less than the SOC error rate of the SOC curve P1 generated in the SOC curve generation step (S200).

[0156] Further, the control unit 130 can set the corrected SOC curve P2 as a standard curve of the battery cell B.

[0157] Accordingly, the battery management method according to another embodiment of the present disclosure has the advantage of setting a more suitable standard curve for the battery cell B by correcting the SOC curve P1 generated using the extended Kalman filter.

[0158] The embodiments of the present disclosure described above cannot be implemented only by the apparatus and the method, but can be implemented by a program implementing a function corresponding to the configuration of the embodiments of the present disclosure or a recording medium on which the program is recorded. A person skilled in the art can easily implement the program or the recording medium according to the above description of the embodiments.

[0159] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, although indicating preferred embodiments of the present disclosure, are given by way of illustration only, since various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

[0160] Additionally, a person skilled in the art can make many substitutions, modifications, and changes to the present disclosure described above without departing from the technical aspects of the present disclosure, and the present disclosure is not limited to the embodiments described above and the accompanying drawings, but each embodiment can be selectively combined in part or in whole to allow various modifications.

[0161] (Reference Signs)

[0162] 1: battery pack

[0163] 100: battery management apparatus

[0164] 110: battery information estimation unit

[0165] 120: curve generation unit

[0166] 130: control unit

[0167] 140: storage unit

[0168] 200: measurement unit

[0169] B: battery cell

Claims

1. A battery management device comprising: a battery information estimation unit configured to estimate battery information including an OCV and an SOC of a battery cell based on at least one of a voltage and a current of the battery cell; a curve generation unit configured to receive the OCV and the SOC from the battery information estimation unit and generate an SOC curve representing a correspondence between the OCV and the SOC; and a control unit configured to: receive the SOC curve from the curve generation unit; determine an inflection point in the received SOC curve; when there is at least one inflection point in the SOC curve, set a correction interval including the inflection point in the SOC curve; and correct the SOC curve by linearizing the set correction interval. 2.The battery management device according to claim 1, the control unit is configured to remove the inflection point included in the correction interval of the SOC curve by applying a linearization algorithm to the correction interval. wherein, 3.The battery management device according to claim 1, when there are a plurality of inflection points in the SOC curve, the control unit is configured to set a correction interval for each of the plurality of inflection points and linearize the plurality of set correction intervals independently. wherein 4.The battery management device according to claim 3, when at least two of the plurality of set correction intervals overlap, the control unit is configured to set the overlapping at least two correction intervals as one correction interval. wherein, 5.The battery management device according to claim 1, the control unit is configured to: correct the SOC curve a plurality of times while changing a size of the correction interval; calculate an SOC error for each of the plurality of corrected SOC curves based on a preset reference curve; select a target SOC curve having a minimum calculated SOC error among the plurality of corrected SOC curves; wherein and set the selected target SOC curve as a standard curve of the battery cell. 6.The battery management device according to claim 5, the control unit is configured to: calculate an SOC error rate for each OCV for each of the plurality of corrected SOC curves by comparing an SOC for each OCV for the reference curve with an SOC for each OCV for each of the plurality of corrected SOC curves; wherein and select a corrected SOC curve in which an error interval of the calculated SOC error rate for each OCV has a minimum size among the plurality of corrected SOC curves as the target SOC curve. 7.The battery management device according to claim 6, the control unit is configured to select an SOC curve in which an error interval representing a difference between a minimum value and a maximum value of the calculated SOC error rate for each OCV for each of the plurality of corrected SOC curves has a minimum size as the target SOC curve. wherein 8.The battery management device according to claim 1, ​ wherein The control unit is configured to set a plurality of filter intervals based on the start point and the end point of the correction interval in the corrected SOC curve, respectively, and apply a filter algorithm to each of the plurality of set filter intervals.

9. The battery management device according to claim 8, wherein, The plurality of filter intervals are configured to include a linear interval and a nonlinear interval based on the start point or the end point, and wherein the control unit is configured to correct each of the plurality of filter intervals by using the filter algorithm so that the linear interval and the nonlinear interval become a continuous interval.

10. The battery management device according to claim 1, wherein The battery information estimating unit is configured to estimate OCV and SOC corresponding to each other from a voltage and a current of the battery cell by using an equivalent circuit model and an extended Kalman filter.

11. A battery pack including the battery management device according to any one of claims 1 to 10.

12. A battery management method comprising: a battery information estimating step of estimating battery information including OCV and SOC of a battery cell based on at least one of a voltage and a current of the battery cell; an SOC curve generating step of generating an SOC curve representing a correspondence between the OCV and the SOC estimated in the battery information estimating step; an inflection point determining step of determining an inflection point in the SOC curve; a correction interval setting step of setting a correction interval including the inflection point in the SOC curve when there is at least one inflection point in the SOC curve; and an SOC curve correcting step of correcting the SOC curve by linearizing the correction interval set in the correction interval setting step.

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