EP-4737923-A1 - CELL THERMAL RUNAWAY DETECTION AND LOCATING METHOD AND APPARATUS FOR BATTERY SYSTEM

Abstract

The present disclosure provides a method for detecting and locating thermal runaway of a battery cell in a battery system. The method includes: obtaining a quantity of battery cells in a battery system; setting a same quantity of resistors with different resistance values based on the quantity of battery cells; connecting a temperature switch in parallel to each resistor, and connecting each parallel unit in series; placing the temperature switch in each parallel unit connected in series on an explosion-proof valve area of each battery cell; labeling the resistor in each parallel unit connected in series with a different resistance value for each battery cell; determining a total resistance value after the series connection in the battery system; and when the total resistance value after the series connection is a labeled resistance value of a corresponding battery cell, determining that the corresponding battery cell undergoes thermal runaway. In this way, a position of a specific runaway battery cell can be located accurately, thereby performing fire prevention and extinguishing accurately to reduce a risk of a safety accident caused by combustion of the battery system and minimize a loss.

Inventors

• CHEN, Jiawen
• SUN, Junpeng
• YU, MIN
• LI, JIANHUI
• SUN, Gaixian

Assignees

• Guangzhou Amphenol Sincere Flex Circuits Co., Ltd

Dates

Publication Date

20260506

Application Date

20240809

Claims (10)

1. A method for detecting and locating thermal runaway of a battery cell in a battery system, comprising following steps: S1: obtaining a quantity of battery cells in a battery system; S2: setting a same quantity of resistors with different resistance values based on the quantity of battery cells; S3: connecting a temperature switch in parallel to each resistor, and connecting each parallel unit in series; S4: placing the temperature switch in each parallel unit connected in series on an explosion-proof valve area of each battery cell; S5: labeling the resistor in each parallel unit connected in series with a different resistance value for each battery cell; and S6: determining a total resistance value after the series connection in the battery system; and when the total resistance value after the series connection is a labeled resistance value of a corresponding battery cell, determining that the corresponding battery cell undergoes thermal runaway.
2. The method for detecting and locating thermal runaway of a battery cell in a battery system according to claim 1, wherein in the step S6, when the total resistance value after the series connection is equal to a resistance value of a circuit itself plus a resistance value of a temperature switch, it is determined that no thermal runaway occurs in the battery cell in the battery system.
3. The method for detecting and locating thermal runaway of a battery cell in a battery system according to claim 1, wherein a threshold for disconnecting the temperature switch is less than a threshold for breaking through the explosion-proof valve area of the battery cell.
4. The method for detecting and locating thermal runaway of a battery cell in a battery system according to claim 1, wherein the temperature switch is a PTC fuse switch.
5. The method for detecting and locating thermal runaway of a battery cell in a battery system according to claim 4, wherein thermally conductive copper foils are respectively provided on two ends of a pad of the PTC fuse switch on the explosion-proof valve area of the battery cell.
6. The method for detecting and locating thermal runaway of a battery cell in a battery system according to claim 5, wherein pre-stress grooves are provided on an explosion-proof cover plate on the explosion-proof valve area of the battery cell, and respectively disposed on two sides of each of the two thermally conductive copper foils.
7. The method for detecting and locating thermal runaway of a battery cell in a battery system according to claim 6, wherein the pre-stress groove is an H-shaped pre-stress groove, and the two thermally conductive copper foils at the two ends of the pad of the PTC fuse switch each are provided with a circuit lead that longitudinally passes through the H-shaped pre-stress groove and is connected to two terminals of the resistor connected in parallel to the PTC fuse switch.
8. A device for detecting and locating thermal runaway of a battery cell in a battery system, comprising resistors with a same quantity as battery cells and different resistance values, wherein a temperature switch is connected in parallel to each resistor, and each parallel unit is connected in series, an explosion-proof cover plate is disposed on an explosion-proof valve area of the battery cell, the temperature switch in each parallel unit connected in series is placed on the explosion-proof cover plate corresponding to each battery cell, and each resistor is labeled with a different resistance value.
9. The device for detecting and locating thermal runaway of a battery cell in a battery system according to claim 8, wherein the temperature switch is a PTC fuse switch.
10. The device for detecting and locating thermal runaway of a battery cell in a battery system according to claim 9, wherein thermally conductive copper foils are respectively disposed at two ends of a pad of the PTC fuse switch on the explosion-proof valve area of the battery cell, pre-stress grooves are provided on the explosion-proof cover plate, and respectively disposed on two sides of each of the two thermally conductive copper foils, the pre-stress groove is an H-shaped pre-stress groove, and the two thermally conductive copper foils at the two ends of the pad of the PTC fuse switch each are provided with a circuit lead that longitudinally passes through the H-shaped pre-stress groove and is connected to two terminals of the resistor connected in parallel to the PTC fuse switch.

Description

TECHNICAL FIELD The present disclosure relates to the field of power batteries, and in particular, to a method and device for detecting and locating thermal runaway of a battery cell in a battery system. BACKGROUND Thermal runaway of a battery cell in a battery system may lead to battery failure or even combustion, causing a safety accident. Therefore, when the thermal runaway occurs, it is necessary to perform detection and pre-warning in a timely manner to ensure that vehicles and personnel take action measures to reduce a risk and minimize a loss. In the prior art, one method is to install a thermal runaway gas detection sensor in the battery system, such that whether the thermal runaway occurs is determined by detecting a composition of gas erupted after the thermal runaway of the battery cell. However, the gas detection sensor in this method is affected by a type and a concentration of the gas. Under a low concentration, a false alarm may be easily reported due to external environmental interference, or under a high concentration, a pre-warning signal is delayed, making it impossible to locate a position of a specific runaway battery cell and perform fire prevention and extinguishing accurately. Another method is to install a thermal runaway gas pressure sensor in the battery system, such that whether the thermal runaway occurs is determined by detecting gas pressure in the system after the thermal runaway of the battery cell. However, the gas pressure sensor method is affected by a magnitude of the gas pressure. When the battery cell slowly undergoes runaway, an explosion-proof valve of the battery cell slowly releases gas, and the gas communicates with the outside of the battery system through a vent valve to release pressure. This makes it difficult to quickly establish pressure that can be detected by the pressure sensor inside the battery system, resulting in delayed sending of an early warning of the thermal runaway. As a result, it is impossible to locate the position of the specific runaway battery cell and perform the fire prevention and extinguishing accurately. Still another method is to detect changes in a monomer voltage and a temperature of the battery cell to determine whether the thermal runaway occurs. However, when it is determined, based on the changes in the monomer voltage and the temperature of the battery cell, that the battery cell undergoes the thermal runaway, a voltage change of the battery cell cannot be easily identified due to an impact from an internal status of the battery cell, resulting in misjudgment or delayed pre-warning. For example, when monomers of battery cells are connected in parallel, a detected voltage remains unchanged when one of the parallel battery cells undergoes the thermal runaway. As a result, this causes a misjudgment, which makes it impossible to locate the position of the specific runaway battery cell and perform the fire prevention and extinguishing accurately. SUMMARY An objective of the present disclosure is to provide a method and device for detecting and locating thermal runaway of a battery cell in a battery system, which can locate a position of a specific runaway battery cell, so as to perform fire prevention and extinguishing accurately to reduce a risk and minimize a loss. A method for detecting and locating thermal runaway of a battery cell in a battery system in the present disclosure includes following steps: S1: obtaining a quantity of battery cells in a battery system;S2: setting a same quantity of resistors with different resistance values based on the quantity of battery cells;S3: connecting a temperature switch in parallel to each resistor, and connecting each parallel unit in series;S4: placing the temperature switch in each parallel unit connected in series on an explosion-proof valve area of each battery cell;S5: labeling the resistor in each parallel unit connected in series with a different resistance value for each battery cell; andS6: determining a total resistance value after the series connection in the battery system; and when the total resistance value after the series connection is a labeled resistance value of a corresponding battery cell, determining that the corresponding battery cell undergoes thermal runaway. As a preferred solution of the present disclosure, in the step S6, when the total resistance value after the series connection is equal to a resistance value of a circuit itself plus a resistance value of a temperature switch, it is determined that no thermal runaway occurs in the battery cell in the battery system. As a preferred solution of the present disclosure, a threshold for disconnecting the temperature switch is less than a threshold for breaking through the explosion-proof valve area of the battery cell. As a preferred solution of the present disclosure, the temperature switch is a PTC fuse switch. As a preferred solution of the present disclosure, thermally conductive copper foils are respectively