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KR-20260065758-A - FAULT CELL DIAGNOSIS METHOD AND BATTERY MANAGEMENT SYSTEM AND BATTERY SYSTEM USING THE SAME

KR20260065758AKR 20260065758 AKR20260065758 AKR 20260065758AKR-20260065758-A

Abstract

A battery management system comprising a plurality of battery cells includes a cell voltage monitoring unit for measuring the cell voltage of each of the plurality of battery cells, a cell balancing control unit for controlling cell balancing for the plurality of battery cells, and a main control circuit for diagnosing a battery cell as an abnormal cell if the voltage difference between the cell voltage of the plurality of battery cells when entering a diagnostic mode for diagnosing abnormalities in the plurality of battery cells and the cell voltage of the plurality of battery cells when exiting the diagnostic mode deviates from a predetermined normal range. In the diagnostic mode, the main control circuit controls the cell balancing control unit to discharge the plurality of battery cells with a current of the same magnitude for a predetermined discharge time.

Inventors

  • 박정욱

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260511
Application Date
20260409

Claims (10)

  1. In a battery management system comprising a plurality of battery cells, A cell voltage monitoring unit for measuring the cell voltage of each of the plurality of battery cells above; A cell balancing control unit that controls cell balancing for the plurality of battery cells; and The main control circuit includes a diagnostic mode for diagnosing whether at least one of the plurality of battery cells is abnormal, a voltage difference between the cell voltage of the at least one battery cell when entering the diagnostic mode and the cell voltage of the at least one battery cell when exiting the diagnostic mode, and a diagnosis of the at least one battery cell as an abnormal cell if the voltage difference deviates from a predetermined normal range. The above main control circuit is, A battery management system in which, in the above diagnostic mode, the cell balancing control unit controls the at least one battery cell to discharge with a current of the same magnitude for a predetermined discharge time.
  2. In paragraph 1, The cell voltage monitoring unit measures the voltage of at least one battery cell when entering the diagnostic mode, and The cell balancing control unit controls the discharge of the at least one battery cell during the discharge time, and the cell voltage monitoring unit measures the cell voltage of the at least one battery cell at the end of the discharge time. The above main control circuit is, A battery management system that determines whether the voltage difference between the cell voltage of the at least one battery cell measured at the end of the discharge time and the voltage of each of the at least one battery cell when entering the diagnostic mode is outside the normal range.
  3. In paragraph 1, The above main control circuit is, A battery management system that performs the diagnostic mode during a rest period when no charge or discharge current flows through the battery.
  4. A battery comprising a plurality of battery cells; A cell balancing unit that performs cell balancing for the plurality of battery cells; and A battery system comprising a battery management system that enters a diagnostic mode for diagnosing whether at least one of the plurality of battery cells is abnormal, measures the cell voltage of the at least one battery cell when entering the diagnostic mode, performs a diagnostic mode in which the cell balancing unit controls the at least one battery cell to discharge at the same magnitude of current for a predetermined discharge time, checks the voltage difference between the cell voltage of the at least one battery cell when ending the diagnostic mode and the cell voltage of the at least one battery cell when entering the diagnostic mode, and diagnoses a battery cell in which the voltage difference deviates from a predetermined normal range as an abnormal cell.
  5. In paragraph 4, The battery management system measures the voltage of each of the at least one battery cell when entering the diagnostic mode, and A battery system comprising: a cell balancing unit discharging the at least one battery cell for a discharge time; a battery management system measuring the cell voltage of the at least one battery cell at the end of the discharge time; and determining whether the voltage difference between the cell voltage of the at least one battery cell measured at the end of the discharge time and the voltage of each of the at least one battery cell at the time of entering the diagnostic mode deviates from the normal range.
  6. In paragraph 4, The above battery management system is, A battery system that performs the diagnostic mode while a vehicle equipped with the above battery system is kept in a key-off state.
  7. A method for diagnosing an abnormal cell in a battery system comprising at least one battery cell, A step for determining whether to enter diagnostic mode; A step of measuring the cell voltage of at least one battery cell when entering the above diagnostic mode; A step of discharging the at least one battery cell with a current of the same magnitude for a predetermined discharge time; A step of measuring the cell voltage of at least one battery cell at the end of the discharge time; A step of checking the voltage difference between the cell voltage of the at least one battery cell measured at the time of entering the diagnostic mode and the cell voltage of the at least one battery cell measured at the time of ending the discharge time when the above diagnostic mode ends, and determining whether the voltage difference deviates from a predetermined normal range; and A method for diagnosing an abnormal cell, comprising the step of determining a battery cell as an abnormal cell when the voltage difference is outside the normal range.
  8. In Paragraph 7, The step of discharging the at least one battery cell with a current of the same magnitude during the above discharge time is, A method for diagnosing an abnormal cell, comprising the step of discharging at least one battery cell for the discharge time.
  9. In paragraph 8, The step of determining whether the above voltage difference deviates from a predetermined normal range is, A method for diagnosing an abnormal cell, comprising the step of determining whether the voltage difference between the cell voltage of the at least one battery cell measured at the end of the discharge time and the cell voltage of the at least one battery cell when entering the diagnosis mode deviates from the normal range.
  10. In Paragraph 7, The step of determining whether to enter the above diagnostic mode is, A method for diagnosing an abnormal cell, comprising the step of entering the diagnostic mode after a predetermined time has elapsed since the vehicle equipped with the above battery system is turned off.

Description

Falter Cell Diagnosis Method and Battery Management System and Battery System Applying the Same The present disclosure relates to a method for diagnosing abnormal cells, a battery management system applying the same, and a battery system. To diagnose whether a battery cell is abnormal, the battery management system measures cell voltage, cell current, cell temperature, etc. However, since the battery management system utilizes values measured based on the battery's operating conditions, there is a problem in that the diagnosis to determine the presence of abnormalities in the battery cell is performed in a limited manner. FIG. 1 is a drawing showing a battery system according to one embodiment. FIG. 2 is a flowchart illustrating an abnormal cell detection method according to one embodiment. FIG. 3 is a flowchart illustrating an abnormal cell detection method according to one embodiment. Figure 4 is a graph of voltage fluctuations due to discharge between a normal cell and an abnormal cell. Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components are assigned identical or similar reference numerals, and redundant descriptions thereof will be omitted. The suffixes "module" and/or "part" for components used in the following description are assigned or used interchangeably solely for the ease of drafting the specification and do not have distinct meanings or roles in themselves. Furthermore, in describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments disclosed in this specification, such detailed description will be omitted. Additionally, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification; the technical concept disclosed in this specification is not limited by the attached drawings, and it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the invention. Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between. In this application, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof. FIG. 1 is a drawing showing a battery system according to one embodiment. The battery system of Fig. 1 may be a power source that supplies power to an electrical load (3), such as a motor, mounted on a vehicle to drive the vehicle. The Electronic Control Circuit (ECU) (2) equipped in the vehicle and the Battery Management System (BMS) (10) of the battery system (1) can transmit and receive necessary information through CAN communication. The battery system (1) includes a battery (10), a battery management system (BMS) (20), a cell balancing unit (30), a relay unit (50), a fuse (60), and a current sensor (70). As illustrated in FIG. 1, the battery (10) includes a plurality of battery cells (11-15) connected in series. In FIG. 1, the battery (10) is shown as including five battery cells (11-15), but this is merely an example and the invention is not limited thereto. The fuse (60) is connected between the positive terminal and the output terminal (+) of the battery (10) and can be blown when the temperature reaches a critical value due to an overcurrent. The relay unit (50) controls the current path during charging and discharging of the battery (10). The closing and opening of the relay unit (50) is controlled according to the relay control signal (RSC) supplied from the BMS (20). The current sensor (70) detects the current flowing through the battery (10) (hereinafter, battery current), and the current sensor (70) can transmit a signal indicating the detected current to the BMS (20). The BMS (20) controls the charging and discharging current of the battery (10) based on information such as cell voltage and battery current of the multiple battery cells (11-15), controls cell balancing operations for the multiple battery cells (11-15), and can diagnos