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KR-102965212-B1 - BATTERY DIAGNOSIS APPARATUS, BATTERY PACK, ELECTRIC VEHICLE AND BATTERY DIAGNOSIS METHOD

KR102965212B1KR 102965212 B1KR102965212 B1KR 102965212B1KR-102965212-B1

Abstract

A battery diagnostic device, a battery pack, an electric vehicle, and a battery diagnostic method are provided. The battery diagnostic device includes a sensing unit that generates a detection signal representing the voltage of a battery cell, and a control circuit that generates voltage time series data of the battery cell using the detection signal. Based on the voltage time series data, the control circuit generates a Q-V profile representing the correspondence relationship between the capacity and voltage of the battery cell, a normalized Q-V profile representing the correspondence relationship between the normalized capacity and voltage of the battery cell, and a Q-dV/dQ profile representing the correspondence relationship between the normalized capacity and differential voltage of the battery cell. Based on the voltage time series data, the control circuit determines a profile characteristic parameter of the battery cell from the Q-V profile of interest, which is the high-capacity side portion of the Q-dV/dQ profile. Based on the profile characteristic parameter, the control circuit determines at least one degradation parameter.

Inventors

  • 김태현
  • 김영덕
  • 최현준

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260513
Application Date
20250812

Claims (13)

  1. A step of generating a normalized QV profile representing the correspondence relationship between the normalized capacity and voltage of the battery cell and a Q-dV/dQ profile representing the correspondence relationship between the normalized capacity and differential voltage of the battery cell based on voltage time series data of the battery cell; A step of extracting a QV profile of interest, which is a part of the normalized QV profile, based on the capacity value of the cut-off reference point set from the above Q-dV/dQ profile; A step of generating a corrected interest QV profile by executing a shifting operation and a scaling operation so that the start point and end point of the interest QV profile correspond to a predetermined first reference point and a second reference point, respectively; and A step of determining at least one degradation parameter associated with the degradation state of the battery cell based on the profile characteristic parameter of the corrected interest QV profile above; A battery diagnostic method including
  2. In paragraph 1, The above Q-dV/dQ profile is, A battery diagnostic method that is the derivative of the normalized QV profile above.
  3. In paragraph 1, A step of determining the area of the region of interest corresponding to the above-mentioned corrected interest QV profile as the profile characteristic parameter; A battery diagnostic method including
  4. In paragraph 1, The step of determining at least one degradation parameter associated with the degradation state of the battery cell is, A step of determining a first degradation parameter of the battery cell by inputting the above profile characteristic parameter into a linear regression model; A battery diagnostic method including
  5. In paragraph 4, The step of determining at least one degradation parameter associated with the degradation state of the battery cell is, A step of determining a second degradation parameter of the battery cell based on the total capacity degradation rate of the battery cell and the first degradation parameter; A battery diagnostic method including further
  6. A recording medium having a program that executes a battery diagnostic method according to any one of paragraphs 1 to 5.
  7. A control circuit that generates a normalized QV profile representing the correspondence relationship between the normalized capacity and voltage of the battery cell and a Q-dV/dQ profile representing the correspondence relationship between the normalized capacity and differential voltage of the battery cell based on voltage time series data of the battery cell; wherein The above control circuit is, Based on the capacity value of the cut-off reference point set from the above Q-dV/dQ profile, the QV profile of interest, which is a part of the normalized QV profile, is extracted, and A shifting operation and a scaling operation are executed so that the start point and end point of the above interest QV profile correspond to a predetermined first reference point and a second reference point, respectively, to generate a corrected interest QV profile, and A battery diagnostic device configured to determine at least one degradation parameter associated with the degradation state of the battery cell based on the profile characteristic parameter of the above-mentioned corrected interest QV profile.
  8. In Paragraph 7, The above Q-dV/dQ profile is, A battery diagnostic device that is the derivative of the above normalized QV profile.
  9. In Paragraph 7, The above control circuit is, A battery diagnostic device configured to determine the area of the region of interest corresponding to the above-mentioned corrected interest QV profile as the profile characteristic parameter.
  10. In Paragraph 7, The above control circuit is, A battery diagnostic device configured to determine a first degradation parameter of the battery cell by inputting the above profile characteristic parameter into a linear regression model.
  11. In Paragraph 10, The above control circuit is, A battery diagnostic device that determines a second degradation parameter of a battery cell based on the total capacity degradation rate of the battery cell and the first degradation parameter.
  12. A battery pack comprising a battery diagnostic device according to any one of paragraphs 7 through 11.
  13. An electric vehicle comprising a battery pack according to paragraph 12.

Description

Battery diagnostic apparatus, battery pack, electric vehicle and battery diagnostic method The present invention relates to a technology for diagnosing the degradation state of a battery cell. Recently, as the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased rapidly, and the development of electric vehicles, energy storage batteries, robots, and satellites has accelerated, research on high-performance batteries capable of repeated charging and discharging is actively underway. Currently commercialized batteries include nickel-cadmium, nickel-hydrogen, nickel-zinc, and lithium batteries. Among these, lithium batteries are gaining attention for their advantages, such as the ability to freely charge and discharge with almost no memory effect compared to nickel-based batteries, a very low self-discharge rate, and high energy density. There are various techniques for monitoring the degradation of battery cells. In particular, Differential Voltage Analysis (also referred to as 'DVA') is based on time series data of at least one battery parameter (e.g., voltage, current) observable from outside the battery cell. In DVA, peaks appearing on the differential voltage curve (which can be referred to as the 'Q-dV/dQ profile') are considered as key factors, but some types of battery cells have a voltage flatness characteristic in which the rate of change of voltage remains close to zero during charging or discharging. Since the differential voltage is also close to zero within the capacity range exhibiting the voltage flatness characteristic, it is difficult to detect peaks from the Q-dV/dQ profile. Therefore, a method is required to accurately and easily diagnose the degradation state of a battery cell without extracting peak information indicating the degradation state from the Q-dV/dQ profile. The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is a diagram illustrating the configuration of an electric vehicle according to the present invention in an exemplary manner. Figure 2 is a graph illustrating an example of the QV profile of a battery cell. Figure 3 is an example of a normalized QV profile obtained from the QV profile of Figure 2. Figure 4 is an example of a Q-dV/dQ profile associated with the normalized QV profile shown in Figure 3. Figure 5 is a graph showing an example of a QV profile of interest extracted from the normalized QV profile of Figure 4. Figure 6 is an example of a corrected interest QV profile obtained from the interest QV profile of Figure 5. FIG. 7 is a figure referenced to illustrate the relationship between different anodic degradation degrees and corrected QV profiles of interest. Figure 8 is a figure referenced to exemplarily explain the relationship between different anodic degradation degrees and the area of the region of interest. FIG. 9 is a flowchart schematically illustrating a battery diagnostic method according to one embodiment of the present invention. FIG. 10 is a flowchart illustrating exemplary subroutines that may be included in step S920 of FIG. 9. FIG. 11 is a flowchart illustrating exemplary subroutines that may be included in step S930 of FIG. 9. FIG. 12 is a flowchart illustrating exemplary subroutines that may be included in step S950 of FIG. 9. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application. Terms including ordinal numbers, such as first, second, etc., are used for the purpose of distinguishing one of the various components from the rest, and are not used to limit the components by such terms. Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Add