JP-2026074515-A - Battery module anomaly detection device

JP2026074515AJP 2026074515 AJP2026074515 AJP 2026074515AJP-2026074515-A

Abstract

[Problem] To detect a disconnection in a short time in a battery module in which multiple batteries are connected in parallel. [Solution] The battery module has multiple batteries connected in parallel. The battery ECU calculates a first voltage value Uocv(k) corresponding to the OCV of the battery module from the terminal voltage VB and input/output current IB of the battery module (S10), and subtracts the previous first voltage value Uocv(k-1) to obtain the first voltage change ΔUocv (S11). Using the SOC-OCV characteristics from the SOC estimated by the Coulomb counting method, the second voltage value OCV(k) is calculated (S12), and subtracts the previous second voltage value OCV(k-1) to obtain the second voltage change ΔOCV (S13). When the difference between the first voltage change ΔUocv and the second voltage change ΔOCV is greater than or equal to a threshold α, it is determined that a break has occurred in the battery module (S15, S16). [Selection Diagram] Figure 2

Inventors

土田祥生

Assignees

トヨタ自動車株式会社

Dates

Publication Date: 20260507
Application Date: 20241021

Claims (1)

An abnormality detection device for a battery module in which multiple batteries are connected in parallel, A first calculation means that estimates a first voltage value of the battery module based on the terminal voltage of the battery module and calculates a first voltage change amount, which is the amount of change in the first voltage value over a predetermined period, A second calculation means that estimates a second voltage value of the battery module based on the current flowing through the battery module and calculates a second voltage change amount, which is the amount of change in the second voltage value during the predetermined period, An abnormality detection device for a battery module, comprising: a determination unit that determines that a wire break has occurred when the difference between the first voltage change and the second voltage change is greater than or equal to a threshold;

Description

This disclosure relates to a battery module anomaly detection device, and more particularly to a battery module anomaly detection device in which multiple batteries are connected in parallel. Japanese Patent Publication No. 2018-73708 (Patent Document 1) discloses a wire break detection system for a secondary battery in which multiple battery cells are connected in parallel. This wire break detection system calculates the difference in salt concentration between the positive and negative electrodes of the battery cells, and allows wire break detection using the resistance method when the salt concentration difference is greater than the judgment salt concentration difference. This is said to suppress false detections. Japanese Patent Publication No. 2018-73708 This is a schematic overall configuration diagram of the battery module abnormality detection device according to this embodiment.This flowchart shows an example of a wire break detection process performed by the battery ECU.This is a diagram illustrating the equivalent circuit model of a battery module. The embodiments of this disclosure will be described in detail below with reference to the drawings. Parts identical or corresponding to those shown in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated. Figure 1 is a schematic overall configuration diagram of the abnormality detection device S for the battery module 100 according to this embodiment. The battery module 100 includes a plurality of batteries 10 connected in parallel. The number of batteries 10 can be any number, as long as it is two or more. The battery 10 may be configured by connecting a plurality of single cells 10A in series. Alternatively, the battery 10 may consist of a single cell. The single cell 10A may be, for example, a lithium-ion battery. Multiple battery modules 100 are connected in series to form a battery pack 1. The number of battery modules 100 constituting the battery pack 1 can be arbitrary. In this embodiment, n battery modules 100 are connected in series to form the battery pack 1. The battery pack 1 is used, for example, as a drive battery for an electric vehicle and is configured to be rechargeable (externally charged) by power from a charging device (not shown). Furthermore, during braking of the electric vehicle, the battery pack 1 (drive battery) may be charged by regenerative power. The monitoring module 20 detects the terminal voltage VB of the battery module 100, the current IB input and output to the battery module 100, the temperature TB of the battery module 100, etc. For example, the terminal voltage VB is detected by the voltage sensor 21, and the current IB is detected by the current sensor 22. The sign of the current IB differs depending on the direction of current flow; it has a positive (+) sign when the battery module 100 is being charged, and a negative (-) sign when the battery module 100 is being discharged. The monitoring module 20 estimates the State of Charge (SOC) of the battery module 100 using the Coulomb count method by integrating the current IB. The monitoring module 20 outputs the terminal voltage VB, current IB, temperature TB, SOC, etc. to the battery ECU (Electronic Control Unit) 30. The monitoring module 20, battery ECU 30, etc., correspond to an example of the "abnormality detection device" of this disclosure. Figure 2 is a flowchart showing an example of the wire break detection process performed by the battery ECU 30. This flowchart is executed for each battery module 100 and is repeated at predetermined intervals. In step 10 (hereinafter, steps are abbreviated as "S"), the first voltage value Uocv(k) is calculated from the terminal voltage VB and current IB. The first voltage value Uocv(k) is the OCV of the battery module 100, estimated based on the terminal voltage VB. Figure 3 is a diagram illustrating the equivalent circuit model of the battery module 100. The equivalent model in this embodiment is an equivalent circuit model in which multiple batteries 10 connected in parallel are treated as a single cell. The voltage change during charging and discharging of the battery involves a mixture of fast reactions caused by electrolyte resistance, charge transfer resistance, etc., and slow reactions caused by an increase in diffusion resistance. The equivalent circuit model in Figure 3 is a well-known model that approximates the fast reactions with a resistive component Ra and represents the diffusion phenomenon inside the electrodes with a parallel circuit of Rb and Cb. In this equivalent circuit model, the approximation formulas (identification formulas) (1) to (5) shown within the dashed lines in Figure 3 hold true. VB(k) is the current terminal voltage VB, and VB(k-1) is the previous terminal voltage VB. IB(k) is the current current IB, and IB(k-1) is the aforementioned current IB. Ts is the calculation period (operation period). Uocv is the OCV of the single cell in the equiv