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EP-4600680-B1 - APPARATUS AND METHOD FOR DIAGNOSING A BATTERY

EP4600680B1EP 4600680 B1EP4600680 B1EP 4600680B1EP-4600680-B1

Inventors

  • KIM, MIN-SEOK
  • KIM, JU-RI
  • BAE, YOON-JUNG
  • JEONG, HEE-SEOK

Dates

Publication Date
20260513
Application Date
20250207

Claims (15)

  1. A method for diagnosing a battery assembly including a battery bank, wherein the battery bank is provided by connecting a plurality of battery cells in parallel with each other, the method comprising: a differential profile generating step (S10) of generating a differential battery bank profile representing a relationship between a differential capacity and the voltage of the battery bank, wherein the differential capacity is obtained by differentiating a capacity of the battery bank with respect to a voltage of the battery bank; the method is characterised by a diagnosing step (S20) of diagnosing a state of the battery bank based on a difference value between a differential capacity value of a target peak located in a predetermined voltage section among a plurality of peaks of the differential battery bank profile and a differential capacity value of a valley adjacent to the target peak.
  2. The method for diagnosing a battery according to claim 1, wherein the differential profile generating step includes: a step of repeatedly measuring a voltage value and a current value of the battery bank using at least one electrical sensor while the battery bank is being charged or discharged; and a step of generating the differential battery bank profile using the voltage values and the current values measured while the battery bank is being charged or discharged.
  3. The method for diagnosing a battery according to claim 1 or 2, wherein the differential profile generating step includes: a step of generating a battery bank profile representing a relationship between the voltage and the capacity of the battery bank; and a step of generating the differential battery bank profile by differentiating the battery bank profile with respect to the voltage of the battery bank.
  4. The method for diagnosing a battery according to one of claims 1 to 3, wherein the diagnosing step includes a step of diagnosing the state of the battery bank as an abnormal state when the difference value is less than a predetermined reference value.
  5. The method for diagnosing a battery according to one of claims 1 to 4, wherein the diagnosing step includes a step of diagnosing the state of the battery bank as an abnormal state in which the plurality of battery cells are unevenly deteriorated, when the difference value is less than a predetermined reference value and the number of target peaks located in the predetermined voltage section exceeds a predetermined reference number.
  6. The method for diagnosing a battery according to one of claims 1 to 5, wherein the diagnosing step includes: a step of calculating a first difference value between a differential capacity value of a first target peak located in a first voltage section among the predetermined voltage sections and a differential capacity value of a first valley adjacent to the first target peak; a step of calculating a second difference value between a differential capacity value of a second target peak located in a second voltage section among the predetermined voltage sections and a differential capacity value of a second valley adjacent to the second target peak; and a step of determining the state of the battery bank as an abnormal state in which the plurality of battery cells are unevenly deteriorated, when the first difference value is less than a predetermined first reference value and the second difference value is less than a predetermined second reference value.
  7. The method for diagnosing a battery according to one of claims 1 to 6, wherein the battery assembly includes a plurality of battery banks, wherein the differential profile generating step includes a step of generating a plurality of differential battery bank profiles respectively corresponding to the plurality of battery banks, and wherein the diagnosing step includes a step of diagnosing a state of each of the plurality of battery banks as a normal state or an abnormal state based on the plurality of differential battery bank profiles.
  8. The method for diagnosing a battery according to one of claims 1 to 7, wherein the diagnosing step includes a step of diagnosing the state of the battery bank as an abnormal state when the difference value is less than a predetermined reference value, and wherein the method for diagnosing a battery further comprises a step of controlling a charger that charges the battery bank to reduce a voltage at an end of charging of the battery bank or reduce a current rate of a current that charges the battery bank, when the state of the battery bank is diagnosed as an abnormal state.
  9. A battery diagnosis apparatus for diagnosing a battery assembly, the battery assembly including a battery bank in which a plurality of battery cells are connected in parallel with each other, the apparatus comprising: a differential profile generating unit (112) configured to generate a differential battery bank profile representing a relationship between a differential capacity, which is obtained by differentiating a capacity of the battery bank with respect to a voltage of the battery bank, and the voltage of the battery bank; the apparatus is characterised by further comprising a diagnosing unit (114) configured to diagnose a state of the battery bank based on a difference value between a differential capacity value of a target peak located in a predetermined voltage section among a plurality of peaks of the differential battery bank profile and a differential capacity value of a valley adjacent to the target peak.
  10. The apparatus for diagnosing a battery according to claim 9, wherein the diagnosing unit is configured to diagnose the state of the battery bank as an abnormal state when the difference value is less than a predetermined reference value.
  11. The apparatus for diagnosing a battery according to claim 9 or 10, wherein the diagnosing unit includes: a calculation module (114a) configured to calculate a first difference value between a differential capacity value of a first target peak located in a first voltage section among the predetermined voltage sections and a differential capacity value of a first valley adjacent to the first target peak and calculate a second difference value between a differential capacity value of a second target peak located in a second voltage section among the predetermined voltage sections and a differential capacity value of a second valley adjacent to the second target peak; and a determination module (114b) configured to determine the state of the battery bank as an abnormal state in which the plurality of battery cells are unevenly deteriorated, when the first difference value is less than a predetermined first reference value and the second difference value is less than a predetermined second reference value.
  12. The apparatus for diagnosing a battery according to one of claims 9 to 11, wherein the battery assembly includes a plurality of battery banks, wherein the differential profile generating unit is configured to generate a plurality of differential battery bank profiles respectively corresponding to the plurality of battery banks, and wherein the diagnosing unit is configured to diagnose a state of each of the plurality of battery banks as a normal state or an abnormal state based on the plurality of differential battery bank profiles.
  13. The apparatus for diagnosing a battery according to one of claims 9 to 12, wherein the diagnosing unit is configured to diagnose the state of the battery bank as an abnormal state when the difference value is less than a predetermined reference value, and wherein the apparatus for diagnosing a battery further comprises a battery management unit (118) configured to control a charger that charges the battery bank to reduce a voltage at an end of charging of the battery bank or reduce a current rate of a current that charges the battery bank, when the state of the battery bank is diagnosed as an abnormal state.
  14. A battery pack comprising the apparatus for diagnosing a battery according to any one of claims 9 to 13.
  15. A vehicle comprising the apparatus for diagnosing a battery according to any one of claims 9 to 13.

Description

This application is based on and claims priority from Korean Patent Application No. 10-2024-0019805, filed on February 8, 2024, with the Korean Intellectual Property Office. TECHNICAL FIELD The present disclosure relates to an apparatus and method for diagnosing a battery, and more particularly, to an apparatus and method for non-destructively diagnosing a state of a battery capable of charging and discharging. BACKGROUND ART Recently, the demand for portable electronic products such as notebook computers, digital cameras and portable telephones has increased sharply, and electric vehicles, energy storage systems, robots, satellites, and the like have been developed in earnest. Accordingly, high-performance batteries allowing charging and discharging and having a high energy density are being actively studied. Types of rechargeable batteries include lithium batteries that use lithium ions, such as lithium-ion batteries or lithium-ion polymer batteries, and nickel cadmium batteries, nickel hydrogen batteries, and nickel zinc batteries. Among these, lithium batteries have the advantages of having a relatively long lifespan, a very low self-discharge rate, and high energy density because they have almost no memory effect compared to batteries that use nickel, and thus their application range is gradually expanding. The positive electrode and negative electrode of these batteries gradually deteriorate as the charge and discharge cycles are repeated, and they no longer maintain the electrical capacity they had at the time of manufacture but are deteriorated. Therefore, in order to accurately predict the usable time, remaining life, and replacement time of the battery, an accurate diagnosis of the battery state is required. However, in diagnosing the battery assembly (e.g., battery module or battery pack) that includes a plurality of battery cells corresponding to the basic units of charge and discharge, the existing technologies perform diagnosis based on the SOH (State of Health) of the corresponding battery assembly. As a result, when the battery assembly includes a plurality of battery banks that are provided by connecting a plurality of battery cells in parallel with each other, the existing technologies have a problem in that they cannot diagnose the state of the corresponding battery assembly for each battery bank, and cannot diagnose whether the battery cells of each battery bank are deteriorated unevenly. ZHANG QI ET AL: "Lithium-ion battery calendar aging mechanism analysis and impedance-based State-of-Health estimation method", JOURNAL OF ENERGY STORAGE, ELSEVIER BV, NL, vol. 64, 21 March 2023 describes Differential Voltage Analysis to explore the variation of lithium intercalation or de-intercalation processes from active materials inside batteries. DISCLOSURE Technical Problem The present disclosure is designed to solve one or more of the problems of the related art. Therefore, some aspects of the present disclosure are directed to providing an apparatus and method for diagnosing a battery, which may diagnose the state of a battery assembly including a plurality of battery banks, which are formed by connecting a plurality of battery cells in parallel, for each battery bank, and may diagnose whether the battery cells of each battery bank are deteriorated unevenly. In the present disclosure, the battery may be a secondary battery and may also be denoted a rechargeable battery. Another technical challenge that the present disclosure seeks to address is to provide an apparatus and method for diagnosing a battery that may extend the life of a battery assembly and improve safety. Technical Solution A method for diagnosing a battery according to first aspect of the present disclosure diagnoses a battery assembly including a battery bank provided by connecting a plurality of battery cells in parallel with each other. The method comprises a differential profile generating step of generating a differential profile representing a relationship between a differential capacity and the voltage of the battery bank. The differential capacity is obtained by differentiating a capacity of the battery bank with respect to a voltage of the battery bank. The method further comprises a diagnosing step of diagnosing a state of the battery bank based on a difference value between a differential capacity value of a target peak located in a predetermined voltage section among a plurality of peaks of the differential profile and a differential capacity value of a valley adjacent to the target peak. The differential profile is also denoted differential battery bank profile in the following. In an embodiment, the differential profile generating step may include a step of repeatedly measuring a voltage value and a current value of the battery bank using at least one electrical sensor. The measurements may be performed while the battery bank is being charged or discharged. The differential profile generating step may further include