CN-121986272-A - Apparatus and method for diagnosing battery

CN121986272ACN 121986272 ACN121986272 ACN 121986272ACN-121986272-A

Abstract

The method for diagnosing a battery according to one aspect of the present disclosure includes a differential curve generating step of generating a differential curve representing a relationship between a voltage and a differential capacity of the battery for each predetermined diagnosis cycle, the differential capacity being obtained by differentiating the capacity of the battery with respect to the voltage, a target peak detecting step of detecting a target peak among peaks of the differential curve, the differential capacity value of the target peak decreasing first and then increasing or the voltage value of the target peak decreasing first and then increasing as a use time of the battery increases, a peak information obtaining step of obtaining target peak information including the differential capacity value and the voltage value of the target peak from each of a plurality of differential curves generated while the diagnosis cycle is repeated a plurality of times, and a diagnosing step of diagnosing a state of the battery based on the target peak information obtained from the plurality of differential curves.

Inventors

YU RENSHAN
LIU ZHONGXUN
Li Zaidai
Pei Yunding

Assignees

株式会社LG新能源

Dates

Publication Date: 20260505
Application Date: 20250121
Priority Date: 20240131

Claims (15)

1. A method for diagnosing a battery, comprising: a differential curve generation step of generating a differential curve representing a relationship between a voltage of the battery and a differential capacity obtained by differentiating the capacity of the battery with respect to the voltage for each predetermined diagnostic cycle; A target peak detection step of detecting a target peak among peaks of the differential curve, a differential capacity value of the target peak decreasing first and then increasing or a voltage value of the target peak increasing first and then decreasing as a use time of the battery increases; a peak information obtaining step of obtaining target peak information including the differential capacity value and the voltage value of the target peak from each of a plurality of differential curves generated while the diagnostic cycle is repeated a plurality of times, and A diagnosis step of detecting a trend switching point at which a change trend of at least one of the differential capacity value and the voltage value of the target peak is switched from an increasing trend to a decreasing trend or from a decreasing trend to an increasing trend over time, based on the target peak information obtained from the plurality of differential curves, and diagnosing a state of the battery by referring to the trend switching point.
2. The method for diagnosing a battery according to claim 1, Wherein the target peak detection step includes: a step of dividing the entire voltage section of the differential curve into a plurality of subsections different from each other and determining a target subsection among the plurality of subsections, and Detecting a peak located in the target subsection among peaks of the differential curve as the target peak.
3. The method for diagnosing a battery according to claim 2, Wherein the target subsections are sections from 4.0[ V ] to 4.2[ V ].
4. The method for diagnosing a battery according to claim 1, Wherein the diagnosing step comprises: a step of detecting a first trend switching point at which a change trend of the differential capacity value is switched from a decreasing trend to an increasing trend with time, and And determining a state of the battery before the first trend switching point as a first degradation state and determining a state of the battery after the first trend switching point as a second degradation state.
5. The method for diagnosing a battery according to claim 4, Wherein the diagnosing step further includes the step of determining that the battery needs to be replaced when the differential capacity value of the target peak exceeds a predetermined first threshold value after the first trend switching point.
6. The method for diagnosing a battery according to claim 1, Wherein the diagnosing step comprises: A step of detecting a second trend switching point at which the trend of the change in the voltage value is switched from an increasing trend to a decreasing trend with time, and And a step of determining a state of the battery before the second trend switching point as a third degradation state and determining a state of the battery after the second trend switching point as a fourth degradation state.
7. The method for diagnosing a battery according to claim 6, Wherein the diagnosing step further includes the step of determining that the battery needs to be replaced when the voltage value of the target peak decreases below a predetermined second threshold value after the second trend switching point.
8. The method for diagnosing a battery according to claim 1, further comprising: a battery management step of lowering an upper voltage limit of the battery when the trend switching point is detected in the diagnosis step.
9. The method for diagnosing a battery according to claim 8, Wherein the battery management step includes: A step of calculating a difference between a first voltage value of the target peak obtained from a most recently generated differential curve among the plurality of differential curves and a second voltage value of the target peak obtained from a differential curve generated immediately before the most recently differential curve, and And a step of lowering the upper voltage limit of the battery in response to the difference value.
10. An apparatus for diagnosing a battery, comprising: A differential curve generation unit configured to generate a differential curve representing a relationship between a voltage of the battery and a differential capacity obtained by differentiating the capacity of the battery with respect to the voltage for each predetermined diagnostic cycle; A peak information obtaining unit configured to detect a target peak among peaks of the differential curves, to increase a differential capacity value of the target peak first and then increase or to increase a voltage value of the target peak first and then decrease as a usage time of the battery increases, and to obtain target peak information including the differential capacity value and the voltage value of the target peak from each differential curve among a plurality of differential curves generated while the diagnostic cycle is repeated a plurality of times, and A diagnostic unit configured to detect a trend switching point at which a change trend of at least one of the differential capacity value and the voltage value of the target peak is switched from an increasing trend to a decreasing trend or from a decreasing trend to an increasing trend over time, based on the target peak information obtained from the plurality of differential curves, and diagnose a state of the battery by referring to the trend switching point.
11. The apparatus for diagnosing a battery according to claim 10, Wherein the diagnostic step unit is configured to detect a first trend switching point at which a change trend of the differential capacity value is switched from a decreasing trend to an increasing trend over time, determine a state of the battery before the first trend switching point as a first degradation state, and determine a state of the battery after the first trend switching point as a second degradation state.
12. The apparatus for diagnosing a battery according to claim 10, Wherein the diagnostic unit is configured to detect a second trend switching point at which a change trend of the voltage value is switched from an increasing trend to a decreasing trend over time, determine a state of the battery before the second trend switching point as a third degradation state, and determine a state of the battery after the second trend switching point as a fourth degradation state.
13. The apparatus for diagnosing a battery according to claim 10, further comprising: and a battery management unit configured to lower an upper voltage limit of the battery when the trend switching point is detected.
14. A battery pack comprising the apparatus for diagnosing a battery according to any one of claims 10 to 13.
15. A vehicle comprising the apparatus for diagnosing a battery according to any one of claims 10 to 13.

Description

Apparatus and method for diagnosing battery Technical Field The present application is based on and claims priority from korean patent application No. 10-2024-0015291, filed on 1 month 31 of 2024, the disclosure of which is incorporated herein by reference in its entirety. 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 battery capable of being charged and discharged. Background Recently, demand for portable electronic products such as notebook computers, digital cameras, and portable phones has drastically increased, and electric vehicles, energy storage systems, robots, satellites, and the like have been greatly developed. Therefore, high-performance batteries that allow charge and discharge and have high energy density are being actively studied. Types of rechargeable batteries include lithium batteries using lithium ions, such as lithium ion batteries or lithium ion polymer batteries, as well as nickel cadmium batteries, nickel hydrogen batteries, and nickel zinc batteries. Among these batteries, lithium batteries have advantages of relatively long life, very low self-discharge rate, and high energy density because they have little memory effect compared to batteries using nickel, and thus their application range is expanding gradually. The positive and negative electrodes of these batteries gradually deteriorate as charge and discharge cycles are repeated, and they no longer maintain the capacitance they had at the time of manufacture, but deteriorate. Therefore, in order to accurately predict the available time, remaining life, and replacement time of the battery, accurate diagnosis of the battery state is required. However, since the related art simply diagnoses the battery through SOH (state of health) of the entire battery, there are problems in that the accuracy and reliability of the diagnosis result are low, and as a result, efficient management corresponding to the current state of the battery is difficult. Disclosure of Invention Technical problem The technical challenge sought to be solved by the present disclosure is to provide an apparatus and method for diagnosing a battery that enables real-time diagnosis of the state of the battery while improving the accuracy and reliability of the diagnosis results. Another technical challenge that the present disclosure seeks to address is to provide an apparatus and method for diagnosing a battery that enables efficient battery management. Technical proposal The method for diagnosing a battery according to one aspect of the present disclosure includes a differential curve generating step of generating a differential curve representing a relationship between a voltage and a differential capacity of the battery for each predetermined diagnosis cycle, the differential capacity being obtained by differentiating the capacity of the battery with respect to the voltage, a target peak detecting step of detecting a target peak among peaks of the differential curve, the differential capacity value of the target peak being decreased before increasing or the voltage value of the target peak being decreased after increasing as a use time of the battery increases, a peak information obtaining step of obtaining target peak information including the differential capacity value and the voltage value of the target peak from each of a plurality of differential curves generated while the diagnosis cycle is repeated a plurality of times, and a diagnosing step of detecting a trend switching point at which a change trend of at least one of the differential capacity value and the voltage value of the target peak is switched from an increasing trend to a decreasing trend or from the decreasing trend to the increasing trend with time, based on the target peak information obtained from the plurality of differential curves, and diagnosing a state of the battery by referring to the switching point. In an embodiment, the target peak detection step may include the step of dividing the entire voltage section of the differential curve into a plurality of subsections different from each other and determining a target subsection among the plurality of subsections, and the step of detecting a peak located in the target subsection among peaks of the differential curve as a target peak. In an embodiment, the target subsections may be sections from 4.0[ V ] to 4.2[ V ]. In an embodiment, the diagnosing step may include a step of detecting a first trend switching point at which a change trend of the differential capacity value is switched from a decreasing trend to an increasing trend over time, and a step of determining a state of the battery before the first trend switching point as a first degradation state and determining a state of the battery after the first trend switching point as a second degradation state. In an embodiment, the diagnosing step may further inclu