Battery parameter estimation apparatus and method

Abstract

According to an embodiment of the present invention, a battery parameter estimation device includes an impedance measurement unit configured to output a plurality of AC currents to a battery and measure a plurality of impedance values ​​for the battery corresponding to the plurality of AC currents; and a control unit configured to generate a first profile by fitting the plurality of impedance values, correct the plurality of impedance values ​​based on the first profile, determine a plurality of reference values ​​based on the plurality of impedance correction values, generate a second profile by fitting the determined plurality of reference values, compare the plurality of impedance correction values ​​with the second profile, and determine whether to set battery parameters according to a comparison result.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2022-0072101, filed on June 14, 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 battery parameters, and more particularly to an apparatus and method for estimating battery parameters by electrochemical impedance spectroscopy (EIS). [Background technology]

[0003] Recently, with the rapid increase in demand for portable electronic products such as laptops, video cameras, and mobile phones, and the full-scale development of electric vehicles, energy storage batteries, robots, satellites, and other products, active research is being conducted on high-performance batteries that can be repeatedly charged and discharged.

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

[0005] Generally, among various battery parameters, Ro (ohmic resistance), Rct (charge transfer resistance), and Cdl (double layer capacitance) can be estimated using an equivalent circuit model (ECM) and EIS. Here, Ro is the ohmic resistance of the battery, and Rct is the charge transfer resistance of the battery. Also, Cdl is the capacitance value of the capacitor included in the equivalent circuit model, which may be the double layer capacitance required for charge separation at the electrodes.

[0006] Figure 1 is a diagram showing a schematic diagram of an equivalent circuit model of a battery, and Figure 2 is a diagram showing a schematic diagram of a Nyquist plot obtained by EIS.

[0007] Here, the Nyquist diagram is obtained by curve fitting multiple data measured by EIS and is divided into a real part (Zre) and an imaginary part (Zim). Ro can be calculated using the real part value at the maximum frequency. Rct can be calculated using the arc (Ark) derived by curve fitting and Ro. Cdl can be calculated based on the angular frequency at the point where the imaginary part of the arc is maximum and Rct. For example, in Figure 2, Cdl can be calculated using the formula "1 ÷ (w × Rct)".

[0008] However, battery parameters estimated by the Nyquist diagram may contain noise in the measurement and / or calculation processes. Non-patent literature discloses a method for calculating the error between the values ​​measured by EIS and the curve fitting values ​​using the Lin-kk (linear kramers kronig) method.

[0009] Battery parameters estimated by EIS can be used to estimate the internal resistance of a battery, which can then be used to estimate the battery's state of health (SOH). Therefore, there is a need to develop technology that can more accurately estimate battery parameters. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] A Method for Improving the Robustness of linear Kramers-Kronig Validity Tests, Electrochimica Acta, 2014 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made to solve the above problems, and an object of the present invention is to provide a battery parameter estimation apparatus and method capable of more accurately estimating battery parameters.

[0012] Other objects and advantages of the present invention can be understood from the following description and will become more apparent from the embodiments of the present invention. Also, it will be easily understood that the objects and advantages of the present invention can be realized by the means recited in the claims and combinations thereof. [Means for solving the problem]

[0013] According to one aspect of the present invention, a battery parameter estimation device may include an impedance measurement unit configured to output a plurality of AC currents to a battery and measure a plurality of impedance values ​​of the battery corresponding to the plurality of AC currents; and a control unit configured to generate a first profile by fitting the plurality of impedance values, correct the plurality of impedance values ​​based on the first profile, determine a plurality of reference values ​​based on the plurality of impedance correction values, generate a second profile by fitting the determined plurality of reference values, compare the plurality of impedance correction values ​​with the second profile, and determine whether to set battery parameters according to a comparison result.

[0014] The control unit may be configured to calculate a first error rate between each of the plurality of impedance values ​​and the first profile, compare the calculated plurality of first error rates with a predetermined first threshold, and correct the plurality of impedance values ​​based on the comparison result.

[0015] The control unit may be configured to delete an impedance value from the plurality of impedance values ​​for which the corresponding first error rate is equal to or greater than the first threshold value.

[0016] The control unit may be configured to calculate a second error rate between the plurality of impedance correction values ​​and the second profile, and compare the calculated second error rate with a preset second threshold value.

[0017] The controller may be configured to set the plurality of reference values ​​as the battery parameters if the second error rate is less than the second threshold.

[0018] The control unit may be configured to, when the second error rate is equal to or greater than the second threshold, regenerate the first profile by fitting the plurality of impedance compensation values, and determine whether to set the battery parameters based on the regenerated first profile and the plurality of impedance compensation values.

[0019] The controller may be configured to regenerate the first profile until the second error rate is less than the second threshold.

[0020] The control unit may be configured to calculate an error rate between each of the plurality of impedance correction values ​​and the second profile, and to calculate an average of the calculated error rates as the second error rate.

[0021] The control unit may be configured to determine an ohmic resistance value, a charge transfer resistance value, and a double layer capacitance value of the battery as the plurality of reference values ​​based on the plurality of impedance correction values.

[0022] A battery pack according to another aspect of the present invention may include a battery parameter estimation device according to an aspect of the present invention.

[0023] According to another aspect of the present invention, a battery parameter estimation method may include an impedance value measuring step of outputting a plurality of AC currents to a battery and measuring a plurality of impedance values ​​of the battery corresponding to the plurality of AC currents; a first profile generating step of generating a first profile by fitting the plurality of impedance values; an impedance value correcting step of correcting the plurality of impedance values ​​based on the first profile; a reference value determining step of determining a plurality of reference values ​​based on the plurality of impedance corrected values; a second profile generating step of generating a second profile by fitting the determined plurality of reference values; a comparison step of comparing the plurality of impedance corrected values ​​with the second profile; and a battery parameter setting determination step of determining whether to set battery parameters based on a comparison result. [Effects of the Invention]

[0024] According to one aspect of the present invention, it is possible to estimate battery parameters with high accuracy and reliability by undergoing primary verification and secondary verification, and it is also possible to improve the accuracy and reliability of the battery state estimated using the battery parameters according to the present invention.

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

[0026] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical concepts of the present invention. Therefore, the present invention should not be interpreted as being limited to only the matters described in the drawings. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a diagram schematically illustrating an equivalent circuit model of a battery. [Figure 2] FIG. 1 is a diagram showing a schematic representation of a Nyquist diagram obtained by EIS. [Figure 3] 1 is a diagram illustrating a battery parameter estimation apparatus according to an embodiment of the present invention; [Figure 4] FIG. 2 is a diagram illustrating a number of impedance values ​​according to an embodiment of the present invention. [Figure 5] FIG. 2 is a diagram illustrating a first profile according to an embodiment of the present invention. [Figure 6] FIG. 4 is a diagram illustrating a first error rate between a plurality of impedance values ​​and a first profile according to an embodiment of the present invention. [Figure 7] FIG. 4 is a diagram illustrating a number of impedance correction values ​​according to an embodiment of the present invention. [Figure 8] FIG. 4 is a diagram illustrating a second profile according to an embodiment of the present invention. [Figure 9] FIG. 10 is a diagram illustrating an exemplary configuration of a battery pack according to another embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating a battery parameter estimation method according to another embodiment of the present invention. [Figure 11] 4 is a diagram illustrating a battery parameter estimation method according to another embodiment of the present invention in more detail. [Figure 12] 4 is a diagram illustrating a battery parameter estimation method according to another embodiment of the present invention in more detail. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary and dictionary meanings, but should be construed as having meanings and concepts corresponding to the technical ideas of the present invention, in accordance with the principle that the inventors themselves can appropriately define the concepts of terms in order to best describe the invention.

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

[0030] Furthermore, when describing the present invention, if it is determined that a detailed description of a related known configuration or function would 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 the various components from the rest, and are not used to limit the components by such terms.

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

[0033] Throughout this specification, when a part is said to be "connected" to another part, this includes not only the case where the part is "directly connected" to another part, but also the case where the part is "indirectly connected" via 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. 3 is a diagram illustrating a battery parameter estimation apparatus 100 according to an embodiment of the present invention.

[0036] Here, a battery refers to a single independent cell that has a negative terminal and a positive terminal and can be physically separated. For example, a lithium ion battery or a lithium polymer battery can be considered a battery. A battery can also refer to a battery module in which multiple cells are connected in series and / or parallel. Hereinafter, for convenience of explanation, a battery will be described as meaning a single independent cell.

[0037] Referring to FIG. 3, the battery parameter estimation apparatus 100 may include an impedance measurement unit 110 and a control unit 120.

[0038] The impedance measurement unit 110 may be configured to output a plurality of alternating currents to the battery.

[0039] Specifically, the impedance measuring unit 110 can output a plurality of AC currents to the battery in order to measure the impedance value of the battery by the EIS method.

[0040] For example, when an impedance measurement signal is received from the control unit 120, the frequency of the AC current may be changed and the AC current may be output to the battery. That is, the AC currents output by the impedance measurement unit 110 may have different frequencies.

[0041] Furthermore, the impedance measurement unit 110 may be configured to measure a plurality of impedance values ​​for the battery corresponding to a plurality of AC currents.

[0042] Specifically, the impedance measuring unit 110 can measure the impedance value of the battery for each of a plurality of AC currents. Therefore, there may be a plurality of impedance values ​​measured by the impedance measuring unit 110. That is, when each of a plurality of AC currents is applied to the battery, an impedance value corresponding to the applied AC current can be measured.

[0043] FIG. 4 is a diagram illustrating a number of impedance values ​​according to an embodiment of the present invention.

[0044] Referring to FIG. 4, a plurality of impedance values ​​corresponding to a plurality of AC currents can be measured. re ) on the X axis, and the imaginary part (Z im Multiple impedance values ​​can be represented on a complex plane with the Y-axis at θ = 1 / 2.

[0045] The control unit 120 may be configured to fit the plurality of impedance values ​​to generate a first profile (p1).

[0046] Specifically, the control unit 120 may be configured to generate the first profile (p1) by applying a fitting algorithm to the plurality of impedance values. Preferably, the control unit 120 may generate the first profile (p1) using a curve fitting algorithm capable of deriving a curve or an approximate function corresponding to the plurality of impedance values. For example, the control unit 120 may generate the first profile (p1) corresponding to the plurality of impedance values ​​using the Lin-KK (Linear Kramers Kronig) algorithm.

[0047] 5 is a diagram illustrating a first profile (p1) according to an embodiment of the present invention. Specifically, the first profile (p1) in FIG. 5 may be an EIS profile generated by the control unit 120 for multiple impedance values ​​using Lin-KK.

[0048] The control unit 120 may be configured to correct the plurality of impedance values ​​based on the first profile (p1).

[0049] The plurality of impedance values ​​are actual values ​​measured by the impedance measuring unit 110, while the first profile (p1) may be an approximation function generated based on the plurality of impedance values. Therefore, there may be a certain degree of error between the plurality of impedance values ​​and the first profile (p1), and the control unit 120 can correct the plurality of impedance values ​​based on such error.

[0050] First, the control unit 120 may be configured to calculate a first error rate between each of the plurality of impedance values ​​and the first profile (p1). Specifically, the control unit 120 may determine a first reference value corresponding to each of the plurality of impedance values ​​in the first profile (p1). For example, the control unit 120 may determine a first reference value corresponding to the frequency in the first profile (p1) by taking into account the frequency of each of the plurality of impedance values. That is, the corresponding impedance value and the first reference value may be values ​​based on the same frequency.

[0051] Next, the control unit 120 can calculate a first error rate between each of the plurality of impedance values ​​and the corresponding first reference value. Specifically, the control unit 120 can calculate the first error rate for each of the plurality of impedance values ​​by calculating the ratio of the first reference value to the impedance value. For example, the control unit 120 can calculate the first error rate for each of the plurality of impedance values ​​by calculating the formula "(impedance value - first reference value) ÷ impedance value."

[0052] In one embodiment, the control unit 120 may calculate a first error rate for each of the real and imaginary values. FIG. 6 is a diagram illustrating a first error rate between a plurality of impedance values ​​and a first profile (p1) according to an embodiment of the present invention. Specifically, FIG. 6 is a diagram illustrating a real error rate ΔRe and an imaginary error rate Δim. Here, the first error rate may include a real error rate ΔRe and an imaginary error rate Δim for the imaginary values. That is, the control unit 120 may calculate an error rate for each of the real and imaginary values ​​to minimize the influence of noise included in the plurality of impedance values.

[0053] Next, the control unit 120 may be configured to compare the calculated first error rates with a preset first threshold value. Here, the first threshold value may be a value preset to correct the impedance values. For example, the first threshold value may be set to a value equal to or less than 5%. Preferably, since the first error rate may be calculated as a negative number, the control unit 120 may compare the magnitude of the calculated first error rates (i.e., the absolute value of the first error rate) with the first threshold value.

[0054] Finally, the control unit 120 may be configured to correct the impedance values ​​based on the comparison results.

[0055] Specifically, the control unit 120 can correct the plurality of impedance values ​​by changing or deleting the impedance values ​​whose first error rate is equal to or greater than the first threshold value.

[0056] For example, the control unit 120 may be configured to delete impedance values ​​(hereinafter, target impedance values) whose corresponding first error rate is equal to or greater than a first threshold value from among the plurality of impedance values. That is, the control unit 120 may delete impedance values ​​containing a large amount of noise, thereby improving the reliability of the plurality of impedance values, which are basis data for estimating battery parameters.

[0057] As another example, the control unit 120 may change the target impedance value to a corresponding first reference value. That is, the control unit 120 may change the target impedance value without deleting it, thereby securing basic data related to the frequency (the frequency corresponding to the target impedance value).

[0058] 5 and 6, it is assumed that the first threshold is preset to 2.5%. The frequency corresponding to the first impedance value d1 may be the first frequency fd1. The control unit 120 may calculate a first error rate (specifically, a real error rate ΔRe and an imaginary error rate Δim) between the first impedance value d1 and the first reference value corresponding to the first frequency fd1 in the first profile (p1). Because the magnitudes of the calculated real error rate ΔRe and imaginary error rate Δim are greater than or equal to the first threshold, the control unit 120 may delete the first impedance value d1.

[0059] 5 and 6, the frequency corresponding to the second impedance value d2 may be the second frequency fd2. The control unit 120 may calculate a first error rate (specifically, a real error rate ΔRe and an imaginary error rate Δim) between the second impedance value d2 and a first reference value corresponding to the second frequency fd2 in the first profile (p1). Because the magnitude of the calculated real error rate ΔRe is equal to or greater than the first threshold, the control unit 120 may delete the second impedance value d2.

[0060] 7 is a diagram illustrating a plurality of impedance compensation values ​​according to an embodiment of the present invention. Comparing FIG. 5 with FIG. 7, the control unit 120 can perform compensation by deleting the first impedance value d1 and the second impedance value d2.

[0061] The controller 120 may be configured to determine a plurality of reference values ​​based on a plurality of impedance correction values.

[0062] Specifically, the control unit 120 may determine parameters of an equivalent circuit model for the battery based on a plurality of impedance correction values.

[0063] For example, the control unit 120 may be configured to determine the ohmic resistance value Ro, the charge transfer resistance value Rct, and the double layer capacitance value Cdl of the battery as the plurality of reference values ​​based on the plurality of impedance correction values.

[0064] The control unit 120 may determine the real value having the maximum frequency among the plurality of impedance compensation values ​​as the ohmic resistance value Ro. For example, in the embodiment of Fig. 7, the control unit 120 may select the first impedance compensation value r1 having the maximum frequency among the plurality of impedance compensation values. Furthermore, the control unit 120 may determine the real value R1 of the first impedance compensation value r1 as the ohmic resistance value Ro.

[0065] 7, the control unit 120 may select a second impedance compensation value r2 corresponding to a frequency at which a Bode plot is minimum among the plurality of impedance compensation values. The control unit 120 may also determine a value obtained by subtracting the real value R1 of the first impedance compensation value r1 from the real value R2 of the second impedance compensation value r2 as the charge transfer resistance value Rct.

[0066] 7, the control unit 120 may select a third impedance compensation value r3 having the largest imaginary value between the first impedance compensation value r1 and the second impedance compensation value r2. The control unit 120 may calculate a double-layer capacitance value Cdl based on a frequency (or angular frequency) corresponding to the third impedance compensation value r3 and a real value R3 of the third impedance compensation value r3. For example, the control unit 120 may calculate the double-layer capacitance value Cdl by calculating the equation "1 ÷ (2 × π × f3 × R3)." Here, f3 is the frequency corresponding to the third impedance compensation value r3, and "2 × π × f3" may be replaced with the angular frequency w for the third impedance compensation value r3.

[0067] The control unit 120 may be configured to generate a second profile (p2) by fitting the determined reference values.

[0068] Specifically, the control unit 120 may be configured to generate the second profile (p2) by applying a fitting algorithm to the plurality of reference values. Preferably, the control unit 120 may generate the second profile (p2) using a curve fitting algorithm that can derive a curve or an approximate function corresponding to the plurality of reference values.

[0069] Since the first profile (p1) is generated based on a plurality of impedance values ​​and the second profile (p2) is generated based on a plurality of reference values ​​(which may include capacitance values ​​in addition to impedance values), the fitting algorithms used by the control unit 120 to generate the first profile (p1) and the second profile (p2) may be different from each other. For example, the control unit 120 may generate the second profile (p2) corresponding to the plurality of reference values ​​using a curve fit in SciPy.

[0070] 8 is a diagram illustrating a second profile (p2) according to an embodiment of the present invention. Specifically, the second profile (p2) in FIG. 8 may be an EIS profile generated by the control unit 120 for multiple reference values ​​using a curve fit in SciPy.

[0071] The control unit 120 may be configured to compare the plurality of impedance correction values ​​with the second profile (p2).

[0072] Specifically, the control unit 120 may be configured to calculate a second error rate between the plurality of impedance correction values ​​and the second profile (p2), and compare the calculated second error rate with a preset second threshold value.

[0073] First, the control unit 120 may be configured to calculate an error rate between each of the plurality of impedance compensation values ​​and the second profile (p2). For example, the control unit 120 may determine a second reference value corresponding to the frequency in the second profile (p2) by taking into account the frequency of each of the plurality of impedance compensation values. That is, the corresponding impedance compensation value and the second reference value may be values ​​based on the same frequency. The control unit 120 may also calculate an error rate between the plurality of impedance compensation values ​​and the corresponding second reference value. Specifically, the control unit 120 may calculate the ratio of the second reference value to the impedance compensation value to calculate the error rate for each of the plurality of impedance compensation values. For example, the control unit 120 may calculate the error rate for each of the plurality of impedance compensation values ​​by calculating the equation "(impedance compensation value - second reference value) ÷ impedance compensation value."

[0074] The control unit 120 may then be configured to calculate an average of the calculated error rates as a second error rate. For example, the control unit 120 may calculate an average of the calculated error rates and set the calculated average as the second error rate. That is, the first error rate may refer to an error rate for each of the multiple impedance values, while the second error rate may refer to an average error rate of the multiple impedance correction values.

[0075] Finally, the control unit 120 may be configured to compare the calculated second error rate with a preset second threshold value. Specifically, the control unit 120 may compare the calculated second error rate with the second threshold value.

[0076] The control unit 120 may be configured to determine whether to set the battery parameters depending on the comparison result.

[0077] For example, the control unit 120 may be configured to set the battery parameters to the reference values ​​when the second error rate is less than the second threshold value, or conversely, the control unit 120 may not set the battery parameters when the second error rate is equal to or greater than the second threshold value.

[0078] Generally, battery parameters can be important elements for constructing an equivalent circuit model, and can be used to estimate the battery's SOH, etc. Therefore, the accuracy and reliability of the battery parameters can have a significant impact on the estimation of the battery's SOH.

[0079] The battery parameter estimation apparatus 100 according to an embodiment of the present invention determines battery parameters after performing primary and secondary verifications using different curve fitting algorithms, and therefore, the battery parameters estimated by the battery parameter estimation apparatus 100 may have high accuracy and reliability. Furthermore, when the SOH of a battery is estimated based on these battery parameters, the SOH may also have high accuracy and reliability.

[0080] Meanwhile, the control unit 120 included in the battery parameter estimation apparatus 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 performing various control logics performed in the present invention. Furthermore, when the control logic is realized in software, the control unit 120 may be realized as a collection of program modules. In this case, the program modules may be stored in memory and executed by the control unit 120. The memory may be internal or external to the control unit 120 and may be connected to the control unit 120 by various well-known means.

[0081] The battery parameter estimation apparatus 100 may further include a storage unit 130. The storage unit 130 may store data and programs necessary for each component of the battery parameter estimation apparatus 100 to operate and function, or data generated during the operation and function. The storage unit 130 may be any known information storage means known to be capable of recording, erasing, updating, and reading data. For example, the information storage means may include a RAM, a flash memory, a ROM, an EEPROM, a register, etc. The storage unit 130 may also store program code defining processes executable by the control unit 120.

[0082] For example, the storage unit 130 may previously store a library of curve fitting algorithms to be used by the control unit 120. The control unit 120 may generate a first profile (p1) and a second profile (p2) using the algorithms stored in the storage unit 130.

[0083] The case where the second error rate is equal to or greater than the second threshold value will be specifically described below.

[0084] The control unit 120 may be configured to regenerate the first profile (p1) by fitting the multiple impedance correction values ​​when the second error rate is equal to or greater than the second threshold.

[0085] Specifically, when the battery parameters cannot be set because the second error rate is equal to or greater than the second threshold, the control unit 120 may treat the plurality of impedance compensation values ​​as the plurality of impedance values. Also, the control unit 120 may regenerate the first profile (p1) by applying a curve fitting algorithm to the plurality of impedance compensation values.

[0086] For example, the control unit 120 may regenerate the first profile (p1) by applying Lin-KK to the plurality of impedance compensation values. That is, the first profile (p1) based on the plurality of impedance values ​​and the first profile (p1) based on the plurality of impedance compensation values ​​may be generated differently because the input data is different.

[0087] In the embodiment of FIG. 8, if a second error rate between the second profile (p2) and the plurality of impedance correction values ​​is greater than or equal to a second threshold, the control unit 120 can regenerate the first profile (p1) for the plurality of impedance correction values.

[0088] The control unit 120 may be configured to determine whether to set battery parameters based on the regenerated first profile (p1) and the plurality of impedance correction values. Preferably, the control unit 120 may be configured to regenerate the first profile (p1) until the second error rate is less than a second threshold.

[0089] Specifically, the control unit 120 may compare the regenerated first profile (p1) with the plurality of impedance recompensation values ​​and recompensate the plurality of impedance recompensation values ​​according to the comparison result. The control unit 120 may also determine a plurality of new reference values ​​based on the plurality of impedance recompensation values. The control unit 120 may generate the second profile (p2) according to the newly determined reference values. Finally, the control unit 120 may compare the generated second profile (p2) with the plurality of impedance recompensation values ​​and determine whether to set battery parameters according to the comparison result. If a second error rate of the plurality of impedance recompensation values ​​is equal to or greater than a second threshold, the first profile (p1) may be regenerated based on the plurality of impedance recompensation values.

[0090] That is, the battery parameter estimation apparatus 100 according to an embodiment of the present invention can update the base data and repeatedly perform the primary verification and the secondary verification until the accuracy and reliability of the set battery parameters reach a predetermined level or higher. Therefore, the accuracy and reliability of the battery parameters estimated by the battery parameter estimation apparatus 100 can be very high.

[0091] The battery parameter estimation apparatus 100 according to the present invention can be applied to a BMS (Battery Management System). That is, the BMS according to the present invention can include the above-described battery parameter estimation apparatus 100. In this configuration, at least some of the components of the battery parameter estimation apparatus 100 can be implemented by complementing or adding functions of components included in a conventional BMS. For example, the impedance measurement unit 110, the control unit 120, and the storage unit 130 of the battery parameter estimation apparatus 100 can be implemented as components of the BMS.

[0092] The battery parameter estimation apparatus 100 according to the present invention may be included in a battery pack 10. That is, the battery pack 10 according to the present invention may include the above-described battery parameter estimation apparatus 100 and one or more battery cells B. The battery pack 10 may further include electrical components (relays, fuses, etc.), a case, etc.

[0093] FIG. 9 is a diagram schematically illustrating an exemplary configuration of a battery pack 10 according to another embodiment of the present invention.

[0094] 9, the impedance measuring unit 110 may be connected to a positive terminal and a negative terminal of the battery cell B. When the impedance measuring unit 110 receives an impedance measurement signal from the control unit 120, the impedance measuring unit 110 may output an AC current to the battery cell B. Furthermore, the impedance measuring unit 110 may output a plurality of AC currents having different frequencies to the battery cell B and measure the impedance of the battery cell B corresponding to each frequency. The impedance measuring unit 110 may transmit the measured impedance values ​​to the control unit 120 and store them in the memory unit 130.

[0095] 10 is a diagram schematically illustrating a method for estimating battery parameters according to another embodiment of the present invention, and FIGS. 11 and 12 are diagrams more specifically illustrating a method for estimating battery parameters according to another embodiment of the present invention.

[0096] Preferably, each step of the battery parameter estimation method can be performed by the battery parameter estimation apparatus 100. Hereinafter, for convenience of explanation, the contents overlapping with the above contents will be omitted or will be explained briefly.

[0097] Referring to FIG. 10, the battery parameter estimation method may include an impedance value measuring step (S100), a first profile generating step (S200), an impedance value correcting step (S300), a reference value determining step (S400), a second profile generating step (S500), a comparison step of the impedance corrected value with the second profile (S600), and a battery parameter setting determining step (S700).

[0098] The impedance value measuring step (S100) is a step of outputting a plurality of AC currents to the battery and measuring a plurality of impedance values ​​for the battery corresponding to the plurality of AC currents, and can be performed by the impedance measuring unit 110.

[0099] For example, the impedance measuring unit 110 can output a plurality of alternating currents having different frequencies to the battery and measure the impedance value corresponding to each frequency.

[0100] The first profile generating step (S200) is a step of generating a first profile (p1) by fitting a plurality of impedance values, and can be performed by the control unit 120.

[0101] For example, the control unit 120 can generate the first profile (p1) by fitting a plurality of impedance values ​​using Lin-KK.

[0102] The impedance value correcting step (S300) is a step of correcting a plurality of impedance values ​​based on the first profile (p1), and can be performed by the control unit 120.

[0103] For example, the control unit 120 can calculate a first error rate between the first profile (p1) and each of the plurality of impedance values, and can correct the plurality of impedance values ​​according to a result of comparing the first error rate with a preset first threshold value.

[0104] Referring to FIG. 11, the impedance value correction step (S300) may include a plurality of first error rate calculation steps (S310), a comparison step (S320) between the first error rate and a first threshold value, and an impedance value deletion step (S320).

[0105] The step of calculating a plurality of first error rates (S310) is a step of calculating a first error rate between each of a plurality of impedance values ​​and the first profile (p1), and can be performed by the control unit 120.

[0106] For example, the control unit 120 can calculate, for each frequency, a first error rate between the impedance value and a first reference value on the first profile (p1).

[0107] The step of comparing the first error rate with the first threshold value (S320) is a step of comparing a plurality of first error rates with a preset first threshold value, and can be performed by the control unit 120.

[0108] For example, the control unit 120 can compare the magnitude of the plurality of first error rates with the first threshold value.

[0109] The impedance value deletion step (S320) is a step of correcting a plurality of impedance values ​​based on the comparison result, and can be performed by the control unit 120.

[0110] For example, the control unit 120 can delete, from among the plurality of impedance values, impedance values ​​whose first error rate is equal to or greater than a first threshold value.

[0111] As another example, the control unit 120 may change an impedance value among the plurality of impedance values ​​whose first error rate is equal to or greater than the first threshold value to a corresponding first reference value. That is, the original impedance value may be deleted, and the plurality of impedance values ​​may include the first reference value.

[0112] The reference value determination step (S400) is a step of determining a plurality of reference values ​​based on a plurality of impedance correction values, and can be performed by the control unit 120.

[0113] For example, the control unit 120 may determine the ohmic resistance Ro, the charge transfer resistance Rct, and the double layer capacitance Cdl of the battery as the plurality of reference values ​​based on the plurality of impedance correction values.

[0114] The second profile generating step (S500) is a step of generating a second profile (p2) by fitting the determined plurality of reference values, and can be performed by the control unit 120.

[0115] For example, the control unit 120 can generate a second profile (p2) corresponding to a plurality of reference values ​​using a curve fit in SciPy.

[0116] The step of comparing the impedance correction values ​​with the second profile (S600) is a step of comparing a plurality of impedance correction values ​​with the second profile (p2), and can be performed by the control unit 120.

[0117] The step of determining whether to set battery parameters (S700) is a step of determining whether to set battery parameters according to the comparison result, and can be performed by the control unit 120.

[0118] For example, the control unit 120 can calculate a second error rate between the second profile (p2) and a plurality of impedance correction values. Furthermore, the control unit 120 can determine whether to configure the battery depending on the result of comparing the second error rate with a preset second threshold value.

[0119] 12, the step of comparing the impedance correction value with the second profile (S600) may include a step of calculating a plurality of error rates (S610), a step of calculating a second error rate (S620), and a step of comparing the second error rate with a second threshold value (S630). The step of determining whether to set the battery parameters (S700) may include a step of comparing (S710) and a step of setting the battery parameters (S720).

[0120] The step of calculating a plurality of error rates (S610) is a step of calculating the error rate between each of a plurality of impedance correction values ​​and the second profile (p2), and can be performed by the control unit 120.

[0121] For example, the control unit 120 can compare each of the multiple impedance correction values ​​with the second reference value on the second profile (p2) and calculate the error rate for the multiple impedance correction values.

[0122] The second error rate calculation step (S620) is a step of calculating an average of the calculated plurality of error rates as a second error rate, and can be performed by the control unit 120.

[0123] For example, the control unit 120 may calculate the second error rate by averaging the plurality of error rates calculated in the step of calculating the plurality of error rates (S610).

[0124] The step of comparing the second error rate with the second threshold value (S630) is a step of comparing the calculated second error rate with a preset second threshold value, and can be performed by the control unit 120.

[0125] For example, the control unit 120 can compare the magnitude of the second error rate with the second threshold value.

[0126] The comparison step (S710) is a step of comparing the second error rate with the second threshold value, and can be performed by the control unit 120.

[0127] For example, if the result of the comparison step (S710) is Yes, the battery parameter setting step (S720) may be performed, and if the result is No, the first profile generation step (S200) may be performed. That is, if the second error rate is equal to or greater than the second threshold, the first profile (p1) may be regenerated based on the plurality of impedance correction values.

[0128] The battery parameter setting step (S720) is a step of setting a plurality of reference values ​​as battery parameters, and can be performed by the control unit 120.

[0129] For example, the control unit 120 may set an ohmic resistance Ro, a charge transfer resistance Rct, and a double layer capacitance Cdl as the battery parameters.

[0130] The embodiments of the present invention described above can be implemented not only by an apparatus and a method, but also by a program that realizes functions corresponding to the configuration of the embodiments of the present invention or a recording medium on which the program is recorded. Such implementation will be easy for an expert in the technical field to which the present invention pertains from the description of the above-mentioned embodiments.

[0131] Although the present invention has been described above using limited embodiments and drawings, it goes without saying that the present invention is not limited thereto, and 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 technical spirit of the present invention and the equivalent scope of the claims set forth below.

[0132] Furthermore, the present invention described above can be variously replaced, modified, and changed by a person having ordinary knowledge in the technical field to which the present invention belongs within the scope that does not deviate from the technical concept of the present invention, and therefore is not limited to the above-described embodiments and the accompanying drawings, and all or part of each embodiment can be selectively combined to make various modifications. [Explanation of symbols]

[0133] 10: Battery pack 100: Battery parameter estimation device 110: Impedance measurement unit 120: Control unit 130: Storage section

Claims

1. an impedance measurement unit that outputs a plurality of AC currents to a battery and measures a plurality of impedance values ​​for the battery corresponding to the plurality of AC currents; a control unit that generates a first profile by fitting the plurality of impedance values, calculates a first error rate between each of the plurality of impedance values ​​and the first profile, compares the calculated plurality of first error rates with a predetermined first threshold, generates a plurality of impedance correction values ​​by changing or deleting impedance values ​​among the plurality of impedance values ​​whose corresponding first error rate is equal to or greater than the first threshold, determines a plurality of reference values ​​related to a Nyquist diagram based on the plurality of impedance correction values, generates a second profile by fitting the determined plurality of reference values, compares the plurality of impedance correction values ​​with the second profile, and determines whether to set the plurality of reference values ​​as battery parameters according to a comparison result.

2. The control unit 2. The battery parameter estimation device according to claim 1, further comprising: calculating a second error rate between the plurality of impedance correction values ​​and the second profile; and comparing the calculated second error rate with a preset second threshold value.

3. The control unit The battery parameter estimation device according to claim 2 , wherein the plurality of reference values ​​are set as the battery parameters when the second error rate is less than the second threshold value.

4. The control unit 3. The battery parameter estimation device of claim 2, further comprising: if the second error rate is equal to or greater than the second threshold, fitting the plurality of impedance correction values ​​to regenerate the first profile; and determining whether to set the battery parameters based on the regenerated first profile and the plurality of impedance correction values.

5. The control unit The battery parameter estimation device of claim 4 , wherein the first profile is regenerated until the second error rate is less than the second threshold.

6. The control unit The battery parameter estimation device according to claim 2 , further comprising: calculating an error rate between each of the plurality of impedance correction values ​​and the second profile; and calculating an average of the calculated error rates as the second error rate.

7. The control unit The battery parameter estimation device according to claim 1 , wherein an ohmic resistance value, a charge transfer resistance value, and a double layer capacitance value of the battery are determined as the plurality of reference values ​​based on the plurality of impedance correction values.

8. A battery pack comprising a battery parameter estimation device according to any one of claims 1 to 7.

9. an impedance value measuring step of outputting a plurality of AC currents to a battery and measuring a plurality of impedance values ​​for the battery corresponding to the plurality of AC currents; a first profile generating step of generating a first profile by fitting the plurality of impedance values; an impedance value correction step of calculating a first error rate between each of the plurality of impedance values ​​and the first profile, comparing the calculated plurality of first error rates with a predetermined first threshold, and changing or deleting impedance values ​​among the plurality of impedance values ​​whose corresponding first error rate is equal to or greater than the first threshold, thereby generating a plurality of impedance correction values; a reference value determining step of determining a plurality of reference values ​​related to a Nyquist diagram based on the plurality of impedance correction values; a second profile generating step of generating a second profile by fitting the determined plurality of reference values; a comparing step of comparing the plurality of impedance correction values ​​with the second profile; and a battery parameter setting determination step of determining whether or not to set the plurality of reference values ​​as battery parameters according to a comparison result.

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