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EP-4206713-B1 - BATTERY DIAGNOSIS APPARATUS, BATTERY PACK, ELECTRIC VEHICLE AND BATTERY DIAGNOSIS METHOD

EP4206713B1EP 4206713 B1EP4206713 B1EP 4206713B1EP-4206713-B1

Inventors

  • LEE, SUN-JONG
  • KIM, CHEOL-TAEK
  • SUNG, YONG-CHUL

Dates

Publication Date
20260513
Application Date
20220712

Claims (15)

  1. A battery diagnosis apparatus, comprising: a voltage detector (110) configured to measure a cell voltage of a battery cell; and a control circuit (140) configured to determine a plurality of sub-voltage curves (S K ) by applying a moving window of a first time length (A) to a reference voltage curve (200, 300), the reference voltage curve (200, 300) being a time series of voltage values indicating the cell voltage measured at each sampling time for a predetermined period of time, characterised in that the control circuit (140) is configured to, for each sub-voltage curve (S K ), determine a long-term average voltage value of the sub-voltage curve (S K ) using a first average filter of the first time length (A), determine a short-term average voltage value of the sub-voltage curve (S K ) using a second average filter of a second time length (B) that is shorter than the first time length (A), and determine a voltage deviation associated with the sub-voltage curve (S K ) by subtracting one of the long-term average voltage value and the short-term average voltage value of each sub-voltage curve (S K ) from the other, and the control circuit (140) is configured to determine whether the battery cell is abnormal by comparing each of a plurality of the voltage deviations determined for the plurality of sub-voltage curves (S K ) with at least one of a first deviation threshold or a second deviation threshold.
  2. The battery diagnosis apparatus according to claim 1, wherein the first deviation threshold is a positive number, and wherein the second deviation threshold is a negative number of which an absolute value is equal to the first deviation threshold.
  3. The battery diagnosis apparatus according to claim 1, wherein the control circuit (140) is configured to determine that the battery cell is abnormal when the voltage deviations of a predetermined number or more of sub-voltage curves (S K ) among the plurality of sub-voltage curves (S K ) are larger than the first deviation threshold or smaller than the second deviation threshold.
  4. The battery diagnosis apparatus according to claim 1, wherein the control circuit (140) is configured to determine that the battery cell is abnormal when any two of the plurality of voltage deviations determined for the plurality of sub-voltage curves (S K ) meet a first requirement, a second requirement and a third requirement, wherein the first requirement is met when one of the two voltage deviations is equal to or larger than the first deviation threshold, wherein the second requirement is met when the other of the two voltage deviations is equal to or smaller than the second deviation threshold, and wherein the third requirement is met when a time interval between the two voltage deviations is equal to or smaller than a threshold time.
  5. The battery diagnosis apparatus according to claim 1, further comprising: a current detector (120) configured to measure a battery current flowing through the battery cell.
  6. The battery diagnosis apparatus according to claim 5, wherein the control circuit (140) is configured to determine a plurality of sub-current curves (R K ) by applying the moving window to a reference current curve (310), the reference current curve (310) being a time series of current values indicating the battery current measured at each sampling time for the predetermined period of time, and wherein the plurality of sub-current curves (R K ) have a one-to-one correspondence with the plurality of sub-voltage curves (S K ).
  7. The battery diagnosis apparatus according to claim 6, wherein the control circuit (140) is configured to, for each sub-current curve (R K ), determine a current change which is a difference between a maximum current value and a minimum current value of the sub-current curve (R K ), and determine the long-term average voltage value and the short-term average voltage value of the sub-voltage curve (S K ) associated with the sub-current curve (R K ) on a condition that the current change is smaller than a threshold change.
  8. A battery pack (10) comprising the battery diagnosis apparatus according to any one of claims 1 to 7.
  9. An electric vehicle (1) comprising the battery pack (10) according to claim 8.
  10. A battery diagnosis method, comprising: measuring a cell voltage of a battery cell at each sampling time for a predetermined period of time, and determining (S710, S810) a plurality of sub-voltage curves (S K ) by applying a moving window of a first time length (A) to a reference voltage curve (200, 300), the reference voltage curve (200, 300) being a time series of voltage values indicating the cell voltage; characterised in that the battery diagnosis method further comprises: for each sub-voltage curve (S K ), determining (S722) a long-term average voltage value of the sub-voltage curve (S K ) using a first average filter of the first time length (A), determining (S724) a short-term average voltage value of the sub-voltage curve (S K ) using a second average filter of a second time length (B) that is shorter than the first time length (A), and determining (S726) a voltage deviation associated with the sub-voltage curve (S K ) by subtracting one of the long-term average voltage value and the short-term average voltage value of each sub-voltage curve (S K ) from the other; and determining (S730, S830) whether the battery cell is abnormal by comparing each of a plurality of the voltage deviations determined for the plurality of sub-voltage curves (S K ) with at least one of a first deviation threshold or a second deviation threshold.
  11. The battery diagnosis method according to claim 10, wherein the first deviation threshold is a positive number, and wherein the second deviation threshold is a negative number of which an absolute value is equal to the first deviation threshold.
  12. The battery diagnosis method according to claim 10, wherein the step of determining whether the battery cell is abnormal comprises determining that the battery cell is abnormal when the voltage deviation of a predetermined number or more of sub-voltage curves (S K ) among the plurality of sub-voltage curves (S K ) is larger than the first deviation threshold or smaller than the second deviation threshold.
  13. The battery diagnosis method according to claim 10, wherein the step of determining whether the battery cell is abnormal comprises determining that the battery cell is abnormal when any two of a plurality of the voltage deviations determined for the plurality of sub-voltage curves (S K ) meet a first requirement, a second requirement and a third requirement, wherein the first requirement is met when one of the two voltage deviations is equal to or larger than the first deviation threshold, wherein the second requirement is met when the other of the two voltage deviations is equal to or smaller than the second deviation threshold, and wherein the third requirement is met when a time interval between the two voltage deviations is equal to or smaller than a threshold time.
  14. The battery diagnosis method according to claim 10, further comprising: Determining (S800) a plurality of sub-current curves (R K ) by applying the moving window to a reference current curve (310), the reference current curve (310) being a time series of current values indicating a battery current measured at each sampling time for the predetermined period of time, and wherein the plurality of sub-current curves (R K ) have a one-to-one correspondence with the plurality of sub-voltage curves (S K ).
  15. The battery diagnosis method according to claim 14, further comprising, for each sub-current curve (R K ), Determining (S812) a current change which is a difference between a maximum current value and a minimum current value of the sub-current curve (R K ), and determining the long-term average voltage value and the short-term average voltage value of the sub-voltage curve (S K ) associated with the sub-current curve (R K ) on a condition that the current change is smaller than a threshold change.

Description

TECHNICAL FIELD The present application claims the benefit of Korean Patent Application No. 10-2021-0091231 filed on July 12, 2021 with the Korean Intellectual Property Office. The present disclosure relates to battery cell anomaly diagnosis. BACKGROUND ART Recently, there has been a rapid increase in the demand for portable electronic products such as laptop computers, video cameras and mobile phones, and with the extensive development of electric vehicles, accumulators for energy storage, robots and satellites, many studies are being made on high performance batteries that can be recharged repeatedly. Currently, commercially available batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries and the like, and among them, lithium batteries have little or no memory effect, and thus they are gaining more attention than nickel-based batteries for their advantages that recharging can be done whenever it is convenient, the self-discharge rate is very low and the energy density is high. More recently, with the widespread use of applications (for example, electric vehicles, energy storage systems) requiring high voltage, there is a growing need for diagnosis technology for accurate anomaly detection for each of a plurality of battery cells connected in series in a battery pack. Prior art usually employs a method of detecting anomalies in each battery cell by comparing the state parameters (for example, a cell voltage) of each battery cell with the state parameters of at least one of the remaining battery cells. However, the corresponding method has disadvantages: (i) since it needs the number of comparison processes corresponding to the number of battery cells, it requires a lot of software resources (computational complexity) and time to individually diagnose anomalies in all the battery cells and (ii) diagnostic errors are more likely to occur with the increasing number of abnormal battery cells. Further examples and embodiments of prior art may be found in US 2020/025832 A1, EP 4 152 021 A1, and JP 2001 027663 A. DISCLOSURE Technical Problem The present disclosure is designed to solve the above-described problem, and therefore the present disclosure is directed to providing a battery diagnosis apparatus, a battery pack, an electric vehicle and a battery diagnosis method for diagnosing anomalies in a single battery cell or each of a plurality of battery cells connected in series using time-dependent changes in cell voltage of each battery cell without a process of comparing the cell voltage of each battery cell with the cell voltage of other battery cell(s). These and other objectives and advantages of the present disclosure may be understood by the following description and will be apparent from an embodiment of the present disclosure. In addition, it will be readily understood that the objectives and advantages of the present disclosure may be realized by the means set forth in the appended claims. Technical Solution A battery diagnosis apparatus according to an aspect of the present disclosure includes a voltage detector configured to measure a cell voltage of a battery cell; and a control circuit configured to determine a plurality of sub-voltage curves by applying a moving window of a first time length to a reference voltage curve, the reference voltage curve being a time series of voltage values indicating the cell voltage measured at each sampling time for a predetermined period of time. The control circuit is configured to, for each sub-voltage curve, determine a long-term average voltage value of the sub-voltage curve using a first average filter of the first time length, determine a short-term average voltage value of the sub-voltage curve using a second average filter of a second time length that is shorter than the first time length, and determine a voltage deviation associated with the sub-voltage curve by subtracting one of the long-term average voltage value and the short-term average voltage value of each sub-voltage curve from the other. The control circuit is configured to determine whether the battery cell is abnormal by comparing each of a plurality of the voltage deviations determined for the plurality of sub-voltage curves with at least one of a first deviation threshold or a second deviation threshold. The first deviation threshold may be a positive number, and the second deviation threshold may be a negative number of which an absolute value is equal to the first deviation threshold. The control circuit may be configured to determine that the battery cell is abnormal when the voltage deviations of a predetermined number or more of sub-voltage curves among the plurality of sub-voltage curves are larger than the first deviation threshold or smaller than the second deviation threshold. The control circuit may be configured to determine that the battery cell is abnormal when any two of the plurality of voltage deviations determined for th