Cell thermal runaway detection and locating method and apparatus for battery system

Abstract

Disclosed in the present invention is a cell thermal runaway detection and locating method for a battery system, comprising: acquiring the number of cells in a battery system; on the basis of the number of cells, providing the same number of resistors having different resistance values; connecting a temperature switch in parallel to each resistor, and connecting parallel units in series; respectively placing the temperature switches of the series-connected parallel units on explosion-proof valve areas of the cells; providing different resistance value identifiers for the resistors of the series-connected parallel units corresponding to the cells; determining a total resistance value after series connection in the battery system; and when the total resistance value after series connection is the resistance value identifier of a corresponding cell, locating that thermal runaway occurs in the cell at the position, so that the specific runaway cell position can be accurately located, enabling precise prevention and extinguishing, thereby reducing the risk of safety accidents caused by battery system combustion and minimizing losses.

Description

A battery system cell thermal runaway detection positioning method and device TECHNICAL FIELD

[0001] The present application relates to the field of power batteries, in particular to a battery system cell thermal runaway detection positioning method and device. BACKGROUND

[0002] Battery system cell thermal runaway can cause battery failure and even burning to cause safety accidents, so when thermal runaway occurs, it needs to be detected and warned in time to ensure that the vehicle and personnel take action measures to reduce risks and losses. In the prior art, one method is to arrange a thermal runaway gas detection sensor in the battery system to determine whether thermal runaway occurs by detecting the gas composition emitted after the cell thermal runaway. However, the gas detection sensor of this method is affected by the gas type and gas concentration, and under low concentration conditions, it is easy to be disturbed by the external environment to cause false alarms, or high concentration conditions are required to cause the delay of the warning signal, so that the specific runaway cell position cannot be located and accurate prevention and elimination cannot be performed. Another method is to arrange a thermal runaway gas pressure sensor in the battery system to determine whether thermal runaway occurs by detecting the gas pressure in the system after the cell thermal runaway. However, the gas pressure sensor of this method is affected by the gas pressure, and when the cell slowly loses control, the cell explosion-proof valve slowly releases gas, and the gas is released through the gas valve and the outside of the battery system to release the pressure, so that it is difficult to quickly establish the pressure that can be detected by the pressure sensor in the battery system, resulting in delay of the thermal runaway warning, so that the specific runaway cell position cannot be located and accurate prevention and elimination cannot be performed. Another method is to determine whether thermal runaway occurs by detecting the cell voltage and temperature changes. However, when the cell loses control, the cell voltage change is affected by the internal state of the cell, so that the cell voltage change does not have obvious identification characteristics, which can cause misjudgment or delay of the warning, for example, when one of the cells in parallel loses control, the detected voltage does not change, so there is a misjudgment, so that the specific runaway cell position cannot be located and accurate prevention and elimination cannot be performed. SUMMARY

[0003] To solve the above problems, the purpose of the present application is to provide a battery system cell thermal runaway detection positioning method and device which can locate the specific runaway cell position, so as to be able to perform accurate prevention and elimination and reduce risks and losses.

[0004] The present application is realized by the following technical scheme:

[0005] The battery system cell thermal runaway detection positioning method provided by the present application comprises the following steps:

[0006] S1, obtaining the number of cells in the battery system;

[0007] S2, setting the same number of resistors with different resistance values according to the number of the battery cells;

[0008] S3, connecting a temperature switch in parallel to each resistor, and connecting each parallel unit in series;

[0009] S4, placing the temperature switch in each parallel unit after series connection on the explosion-proof valve area of each battery cell respectively;

[0010] S5, identifying the resistance value of each battery cell corresponding to the resistance in each parallel unit after series connection;

[0011] S6, judging the total resistance value after series connection in the battery system; when the total resistance value after series connection is the resistance value identification corresponding to the battery cell, it is determined that the battery cell at the position exists thermal runaway.

[0012] As a preferred scheme of the present application, in step S6, when the total resistance value after series connection is the initial design resistance of the line itself resistance and the temperature switch before excitation, it is determined that the battery system does not exist thermal runaway of the battery cell.

[0013] As a preferred scheme of the present application, the threshold value of the temperature switch opening is less than the threshold value of the explosion-proof valve area of the battery cell being blown off.

[0014] As a preferred scheme of the present application, the temperature switch is a PTC fuse switch.

[0015] As a preferred scheme of the present application, the PTC fuse switch pad on the explosion-proof valve area of the battery cell is provided with heat-conducting copper foils at both ends.

[0016] As a preferred scheme of the present application, a pre-stress groove is provided on the explosion-proof cover plate on the explosion-proof valve area of the battery cell, and the pre-stress groove is located on both sides of the two heat-conducting copper foils.

[0017] As a preferred scheme of the present application, the pre-stress groove is an H-shaped pre-stress groove, and the two heat-conducting copper foils at both ends of the PTC fuse switch pad are respectively provided with circuit lead wires longitudinally passing through the H-shaped pre-stress groove and connected to both ends of the resistance in parallel with the PTC fuse switch.

[0018] A battery cell thermal runaway detection and positioning device of a battery system, comprising resistors with different resistance values set according to the number of the battery cells, a temperature switch connected in parallel to each resistor, and each parallel unit connected in series, an explosion-proof cover plate provided on the explosion-proof valve area of the battery cell, the temperature switch in each parallel unit after series connection placed on the corresponding explosion-proof cover plate of each battery cell, and different resistance values identified for each resistor.

[0019] As a preferred scheme of the present application, the temperature switch is a PTC fuse switch.

[0020] As a preferred scheme of the present application, heat-conducting copper foils are arranged at both ends of the PTC fuse switch pad on the explosion-proof valve area of the battery cell, a pre-stress groove is arranged on the explosion-proof cover plate, the pre-stress groove is located on both sides of the two heat-conducting copper foils, the pre-stress groove is an H-shaped pre-stress groove, and the two heat-conducting copper foils at both ends of the PTC fuse switch pad are respectively arranged to connect the two ends of the resistance in parallel with the PTC fuse switch through the H-shaped pre-stress groove in the longitudinal direction.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The battery cell thermal runaway detection and positioning method and device of the battery system, by arranging the temperature switch in each parallel unit after series connection on the explosion-proof valve area of each battery cell and marking different resistance values, when the total resistance value after series connection is the resistance value mark of the corresponding battery cell, the specific runaway battery cell position can be accurately positioned, so that accurate prevention and elimination can be carried out, the risk of safety accidents caused by burning of the battery system is reduced, and the loss is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 is a flow diagram of a battery cell thermal runaway detection and positioning method of a battery system according to the present application;

[0024] Fig. 2 is a circuit diagram of parallel connection of a resistance and a temperature switch according to the present application;

[0025] Fig. 3 is a schematic diagram of a battery cell thermal runaway detection and positioning device of a battery system according to the present application;

[0026] Fig. 4 is an enlarged view of part A of Fig. 3. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] A battery cell thermal runaway detection and positioning method of a battery system, as shown in Fig. 1, the following steps are:

[0029] S1, obtaining the number of battery cells in the battery system.

[0030] Directly obtaining the number of battery cells currently connected to the system from the battery system.

[0031] S2, setting resistances with the same number of different resistance values according to the number of battery cells. S3, connecting the resistances in parallel with the temperature switch in each parallel unit after series connection.

[0032] Each battery cell is provided with one resistor, and the resistance of each resistor is different. The resistor is a general ordinary resistor.

[0033] S3, a temperature switch is connected in parallel to each resistor, and each parallel unit is connected in series.

[0034] A temperature switch is connected in parallel to each resistor. The temperature switch can be a PTC fuse switch. The threshold of the PTC fuse switch is smaller than the threshold at which the explosion-proof valve area of the battery cell is blown open. Thus, the two functions of early prevention and failure detection can be realized. When the temperature of the battery cell rises to the threshold at which the PTC fuse switch is disconnected, but the threshold at which the explosion-proof valve area of the battery cell is blown open is not blown open, the heat of the battery cell excites the temperature switch in the form of heat conduction, heat radiation, etc., thereby realizing early warning. When the thermal runaway of the battery cell is intensified, further causing the explosion-proof valve area of the battery cell to be blown open, the high-temperature and high-pressure gas or flame excites the PTC fuse switch or damages the PTC fuse switch area, resulting in disconnection, thereby realizing the thermal runaway detection function.

[0035] S4, the temperature switch in each parallel unit after series connection is respectively arranged on the explosion-proof valve area of each battery cell.

[0036] An explosion-proof cover plate is arranged on the explosion-proof valve area of the battery cell. A pre-stressed groove is arranged on the explosion-proof cover plate. The pre-stressed groove is an H-shaped pre-stressed groove. The pre-stressed groove is arranged on both sides of two pieces of heat-conducting copper foil. The two pieces of heat-conducting copper foil are respectively provided with circuit lead wires which are longitudinally arranged through the H-shaped pre-stressed groove and connected to the ends of the resistor in parallel with the PTC fuse switch. The heat-conducting copper foil is efficient in heat conduction. When the battery cell is ejected, the heat-conducting copper foil is arranged above the explosion-proof valve of the battery cell. The heat is conducted to the PTC fuse switch through the large-area copper foil, thereby more efficiently exciting the function of the PTC fuse switch and further speeding up the accurate positioning to the specific runaway battery cell position. In addition, the pre-stressed groove is designed as an H-shaped pre-stressed groove. The high-pressure gas ejected from the battery cell is released through the H-shaped pre-stressed groove area. When the pressure is sufficient, the H-shaped pre-stressed groove can break the circuit lead wires at both ends of the PTC fuse switch, thereby further speeding up the accurate positioning to the specific runaway battery cell position.

[0037] S5, the resistors in each parallel unit after series connection are marked with different resistance values corresponding to each battery cell.

[0038] S6, the total resistance value after series connection in the battery system is judged. When the total resistance value after series connection is the resistance value mark corresponding to the battery cell, it is determined that the battery cell at this position has thermal runaway. When the total resistance value after series connection is the initial design resistance before the temperature switch is excited, it is determined that the battery system does not have thermal runaway of the battery cell.

[0039] A kind of battery system electric core thermal runaway detection positioning device, as shown in Figure 2-4, including the resistance R of setting with the same number of electric core different resistance value, each resistance is connected in parallel with a temperature switch PTC, and each parallel unit is connected in series, explosion-proof cover plate 1 is arranged on the explosion-proof valve area of electric core, the temperature switch in each parallel unit after series connection is placed on each electric core corresponding explosion-proof cover plate respectively, and the resistance of each resistance is marked with different resistance value.

[0040] By placing the temperature switch in each parallel unit after series connection on the explosion-proof valve area of each electric core respectively, and marking with different resistance value, when the total resistance value after series connection is the resistance value mark of corresponding electric core, then the specific runaway electric core position can be accurately positioned, so that accurate prevention and elimination can be carried out, reduce the risk of safety accident caused by battery system combustion and reduce loss.

[0041] Temperature switch is PTC fuse switch, both ends of PTC fuse switch pad on the explosion-proof valve area of electric core are provided with heat-conducting copper foil 2, pre-stressed groove is arranged on explosion-proof cover plate, pre-stressed groove is located on both sides of two pieces of heat-conducting copper foil, the pre-stressed groove is H-shaped pre-stressed groove 3, two pieces of heat-conducting copper foil at both ends of PTC fuse switch pad are respectively provided with circuit lead 4, which is connected to both ends of resistance connected in parallel with PTC fuse switch by longitudinally passing through H-shaped pre-stressed groove.

[0042] High-efficiency heat-conducting copper foil, when electric core is ejected, heat-conducting copper foil is arranged above the explosion-proof valve of electric core, heat is conducted to PTC fuse switch through large-area copper foil, so that the function of PTC fuse switch is more efficiently excited, and the specific runaway electric core position is further accurately positioned. In addition, the pre-stressed groove is designed as H-shaped pre-stressed groove, high-pressure gas ejected from electric core is released through H-shaped pre-stressed groove area, when the pressure is sufficient, H-shaped pre-stressed groove can break the circuit lead at both ends of PTC fuse switch pad, further accelerating the accurate positioning to the specific runaway electric core position.

[0043] The initial design resistance of line itself resistance and PTC fuse switch before being excited is small enough to have no influence on circuit detection unit and system. In order to facilitate the demonstration of calculation principle, the value is assumed to be 0, then the electric core thermal runaway detection positioning mode of battery system is as shown in Table 1:

[0044] Total resistance: RT1=(R1xRPTC1) / (R1+RPTC1)=(1x0) / (1+0)=0KΩ; RT2=(R2xRPTC2) / (R2+RPTC2)=(2x0) / (2+0)=0KΩ; RT3=(R3xRPTC3) / (R3+RPTC3)=(3x∞) / (3+∞)=3KΩ; RT4=(R4xRPTC4) / (R4+RPTC4)=(4x0) / (4+0)=0KΩ; RT5=(R5xRPTC5) / (R5+RPTC5)=(5x0) / (5+0)=0KΩ; RTtotal=RT1+RT2+RT3+RT4+RT5=0+0+3+0+0=3KΩ. Thus, the total resistance of the circuit is R3, thereby enabling accurate positioning to the specific out-of-control battery cell 3.

[0045] The above examples are only used to illustrate the detailed schemes of the present application, and the present application is not limited to the above detailed schemes, i.e. it does not mean that the present application must rely on the above detailed schemes to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for cell thermal runaway detection and localization of a battery system, the method comprising: The method comprises the following steps: S1, obtaining the number of battery cells in a battery system; S2, setting resistors with the same number but different resistance values according to the number of battery cells; S3, connecting a temperature switch in parallel to each resistor and connecting each parallel unit in series; S4, placing the temperature switches in each parallel unit after series connection on the explosion-proof valve area of each battery cell; S5, identifying the resistors in each parallel unit after series connection with different resistance values for each battery cell; S6, judging the total resistance value after series connection in the battery system; when the total resistance value after series connection is the resistance value identification of the corresponding battery cell, it is determined that the battery cell at the position has thermal runaway.

2. The cell thermal runaway detection and localization method of claim 1, wherein, In step S6, when the total resistance value after series connection is the initial design resistance of the line itself resistance and the temperature switch before excitation, it is determined that the battery system does not have battery cell thermal runaway.

3. The method of claim 1, wherein, The threshold value of the temperature switch disconnection is less than the threshold value of the explosion-proof valve area of the battery cell being blown off.

4. The method of claim 1, wherein, The temperature switch is a PTC fuse switch.

5. The method of claim 4, wherein: Heat-conducting copper foils are arranged at both ends of the PTC fuse switch pad on the explosion-proof valve area of the battery cell.

6. The cell thermal runaway detection and localization method of claim 5, wherein, A pre-stressed groove is arranged on the explosion-proof cover plate on the explosion-proof valve area of the battery cell, and the pre-stressed groove is located on both sides of the two heat-conducting copper foils.

7. The cell thermal runaway detection and localization method of claim 6, wherein, The pre-stressed groove is an H-shaped pre-stressed groove, and the two heat-conducting copper foils at both ends of the PTC fuse switch pad are respectively arranged with circuit leads longitudinally passing through the H-shaped pre-stressed groove to connect both ends of the resistor in parallel with the PTC fuse switch.

8. A cell thermal runaway detection localization device for a battery system, comprising: The method comprises setting resistors with the same number but different resistance values as the battery cells, connecting a temperature switch in parallel to each resistor, connecting each parallel unit in series, arranging an explosion-proof cover plate on the explosion-proof valve area of the battery cell, placing the temperature switches in each parallel unit after series connection on the corresponding explosion-proof cover plate of each battery cell, and identifying each resistor with different resistance values.

9. The cell thermal runaway detection and localization apparatus of claim 8, wherein, The temperature switch is a PTC fuse switch.

10. The cell thermal runaway detection localization apparatus of claim 9, wherein, Heat-conducting copper foils are arranged at both ends of the PTC fuse switch pad on the explosion-proof valve area of the battery cell, a pre-stressed groove is arranged on the explosion-proof cover plate, the pre-stressed groove is located on both sides of the two heat-conducting copper foils, the pre-stressed groove is an H-shaped pre-stressed groove, and the two heat-conducting copper foils at both ends of the PTC fuse switch pad are respectively arranged with circuit leads longitudinally passing through the H-shaped pre-stressed groove to connect both ends of the resistor in parallel with the PTC fuse switch.

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