Method and device for detecting voltage breakdown of a battery pack simulating insulation abnormality

Abstract

The application provides a voltage breakdown detection method for simulating insulation abnormality of a battery pack, belongs to the field of lithium ion battery testing, removes insulation films of two single batteries to obtain a first film-removed battery and a second film-removed battery, and is used for simulating the battery with insulation abnormality in the battery pack; the two film-removed batteries are placed on a metal plate and are used for simulating the contact between the battery shell and the battery pack box; a high-voltage module is placed on a wooden plate and is used for simulating external high voltage; the negative electrode of the high-voltage module is connected to the positive electrode of the first film-removed battery, and a short circuit tester is connected between the positive electrode of the high-voltage module and the negative electrode of the second film-removed battery; the short circuit tester is turned on and the voltage of the high-voltage module is adjusted; when the current in the loop exceeds the breakdown current or the film-removed battery appears breakdown sparking, the voltage of the high-voltage module is determined as the voltage breakdown value of the battery pack insulation abnormality; and the detection device is also provided; after the insulation film of the battery is preliminarily judged to be damaged, the contact between the battery shell and the battery pack box at which voltage will cause the battery breakdown short circuit is determined.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery testing technology, and in particular to a method and apparatus for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities. Background Technology

[0002] With the development of new energy sources, lithium-ion batteries have become increasingly popular due to their advantages such as low environmental pollution, high energy density, long cycle life, and strong rate performance. As the cost of lithium-ion batteries decreases, their economic benefits are becoming more and more prominent, and their application in the energy storage market is becoming more and more widespread. However, the safety of lithium-ion batteries remains a key concern.

[0003] With the rise of energy storage power stations, lithium-ion battery energy storage power stations are widely used in power system frequency regulation, peak-valley electricity price balancing, renewable energy integration, backup power, microgrids, and other fields, playing an important role in improving the reliability, stability, and sustainability of power systems. However, the operation of energy storage power stations requires a large number of individual units to build a massive battery system, which significantly increases safety concerns. Especially under high external voltage conditions, if the battery's outer insulating film is damaged, a short circuit breakdown is highly likely to occur at the contact point between the metal casing and the battery pack housing. Currently, there is no simple and easy-to-operate detection method to detect whether a short circuit breakdown will occur at the contact point between the metal casing and the battery pack housing under high external voltage conditions, leading to module short circuits, thermal runaway, and safety accidents.

[0004] In the prior art, Chinese invention patent application CN114976330A, entitled "A Method and Device for Determining the Withstand Voltage Value of a Battery Device and its Insulating Film," discloses a method for determining the withstand voltage value of an insulating film in a battery device: Based on a pre-determined withstand voltage test voltage and the maximum voltage of the battery device, the initial withstand voltage value of the insulating film in each insulating structure is determined; the maximum value among these initial withstand voltage values ​​is then determined as the withstand voltage value of the insulating film. This method determines the withstand voltage value of the insulating film under normal battery insulation conditions and cannot simulate the battery pack withstand voltage safety level after an insulation abnormality in the battery module. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to detect the withstand voltage breakdown value of the battery casing insulation film after it is damaged and the contact electrode with the battery pack box under external high voltage.

[0006] This invention solves the above-mentioned technical problems through the following technical solution: a method for detecting withstand voltage breakdown simulating insulation abnormalities in battery packs, comprising:

[0007] The insulating films of two individual cells are removed to obtain cell No. 1 and cell No. 2, which are used to simulate cells with abnormal insulation in the battery pack. Two de-coated batteries were placed on a metal plate to simulate the contact between the battery casing and the battery pack housing; Place the high-voltage module on a wooden board to simulate external high voltage. Connect the negative terminal of the high-voltage module to the positive terminal of the No. 1 membrane-removed battery. Connect a short-circuit tester between the positive terminal of the high-voltage module and the negative terminal of the No. 2 membrane-removed battery. Connect the short-circuit tester and adjust the voltage of the high-voltage module. When the current in the circuit exceeds the breakdown current or the de-filmed battery shows breakdown and arcing, the voltage of the high-voltage module is determined as the withstand voltage breakdown value of the battery pack insulation abnormality.

[0008] This invention simulates the pressure conditions of a battery with abnormal insulation under high voltage, and can preliminarily determine the voltage at which the battery casing and battery pack housing will cause battery breakdown and short circuit after the outer insulating film is damaged. The method is simple and easy to operate.

[0009] Preferably, the battery pack includes n individual cells connected in series, where n is an integer greater than 1. Cell #1 and Cell #2 (with membrane removed) simulate the 1st and kth individual cells in the battery pack, respectively, where 2 ≤ k ≤ n. Cell #1 and Cell #2 (with membrane removed) are used to simulate the situation where the insulating membrane of two individual cells in the battery pack is damaged.

[0010] Preferably, when the battery with insulation defects in the battery pack is a positive electrode weakly conductive battery, the voltage between the positive electrode of the No. 1 removed film battery and the positive electrode of the No. 2 removed film battery is: V, This refers to the voltage of each individual cell. Combined with the breakdown voltage of the positive electrode weak conductor of the positive electrode weak conductor cell, the number of individual cells that might cause a module short circuit when the battery casing and battery box are in contact can be calculated, providing guidance for battery pack design.

[0011] Preferably, a positive electrode weak conduction battery refers to a battery where weak conduction resistance exists only at the positive electrode, and the resistance between the positive electrode of the No. 1 defilmed battery and the positive electrode of the No. 2 defilmed battery is the sum of the resistance of the weak conduction plate of the positive electrode of the No. 1 defilmed battery and the resistance of the weak conduction plate of the positive electrode of the No. 2 defilmed battery.

[0012] Preferably, when the battery with insulation defects in the battery pack is a non-positive electrode weakly conductive battery, the voltage between the positive terminal of the No. 1 removed film battery and the negative terminal of the No. 2 removed film battery is: V, the voltage between the negative terminal of cell #1 (without film removal) and the positive terminal of cell #2 (without film removal) is... V, This involves calculating the voltage of each individual cell. Combined with the breakdown voltage of the insulating sheet of the non-positive-polarity, weakly conductive battery, the number of individual cells that could potentially cause a module short circuit when the battery casing and battery box come into contact can be determined, providing guidance for battery pack design.

[0013] Preferably, a non-positive electrode weakly conductive battery refers to a battery where the positive and negative electrodes each have a large insulating sheet resistance. The resistance between the positive electrode of the No. 1 removed film battery and the negative electrode of the No. 2 removed film battery is the sum of the resistances of the insulating sheets of the positive electrode of the No. 1 removed film battery and the negative electrode of the No. 2 removed film battery. The resistance between the negative electrode of the No. 1 removed film battery and the positive electrode of the No. 2 removed film battery is the sum of the resistances of the insulating sheets of the negative electrode of the No. 1 removed film battery and the positive electrode of the No. 2 removed film battery are connected in parallel with each other.

[0014] Preferably, the two decoated batteries are electrically connected via a metal plate. The continuity between the two batteries is determined by measuring the resistance and voltage between them. This ensures that the two batteries are electrically connected via the metal plate.

[0015] Preferably, the breakdown current is 10A, and the current in the circuit is less than 1A when no breakdown occurs.

[0016] This invention also provides a withstand voltage breakdown detection device for simulating insulation abnormalities in battery packs. The detection method described above includes a first-stage battery and a second-stage battery. Both the first-stage battery and the second-stage battery are located on a metal plate and are connected through the metal plate. The positive terminal of the first-stage battery is connected to the negative terminal of a high-voltage module. The positive terminal of the high-voltage module is connected in series with a short-circuit tester and then connected to the negative terminal of the second-stage battery. The high-voltage module is located on a wooden board.

[0017] This invention uses two batteries with their outer insulating film removed, connected by a metal plate, and then connected to a short-circuit tester. After applying a stable external voltage, it can simulate whether a short circuit will occur when the battery casing's outer insulating film is damaged and comes into contact with the battery pack housing. The operation is simple and easy to implement.

[0018] Preferably, the metal plate is a smooth, uncontaminated, pure conductive metal plate. This ensures that the two membrane-removed batteries achieve metallic conductivity through the metal plate. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] Figure 1 This is a schematic diagram of the withstand voltage breakdown detection method for simulating insulation abnormalities in a battery pack provided in Embodiment 1 of the present invention; Figure 2 This is a flowchart of the withstand voltage breakdown detection method for simulating insulation abnormalities in a battery pack provided in Embodiment 1 of the present invention; Figure 3This is a schematic diagram of the battery pack insulation abnormality in the withstand voltage breakdown detection method for simulating battery pack insulation abnormality provided in Embodiment 1 of the present invention; Figure 4 The equivalent circuit diagram of the single cell being a positive electrode weakly conductive cell in the withstand voltage breakdown detection method for simulating insulation abnormalities in a battery pack provided in Embodiment 1 of the present invention; Figure 5 The equivalent circuit diagram of the withstand voltage breakdown detection method for simulating battery pack insulation abnormalities provided in Embodiment 1 of the present invention is a non-positive electrode weakly conductive battery. In the diagram: 10 No. 1 membrane-removed battery, 20 No. 2 membrane-removed battery, 30 metal plate, 40 high voltage module, 50 wooden board, 60 short circuit tester, 100 positive electrode weak conductor sheet, 200 insulating sheet, 300 battery pack box.

[0021] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] Example 1 See Figure 1 and Figure 2 This embodiment provides a method for simulating voltage breakdown detection of battery pack insulation abnormalities, including the following steps: Step 1: Remove the insulating film from the two individual cells. In practice, this can be achieved by removing the outer blue film at the bottom of the individual cells, resulting in cell 10 (without insulating film) and cell 20 (without insulating film), used to simulate batteries with insulation abnormalities in the battery pack; see [link to relevant documentation]. Figure 3 In this embodiment, the battery pack includes n individual cells connected in series, where n is an integer greater than 1. These n individual cells are numbered as the 1st individual cell, the 2nd individual cell, ..., the kth individual cell, ..., the nth individual cell. The first de-filmed battery 10 and the second de-filmed battery 20 simulate the 1st and kth individual cells in the battery pack, respectively, where 2 ≤ k ≤ n, to simulate the situation where the insulating film of two individual cells in the battery pack is damaged.

[0024] Step 2: Place the two decoated batteries (battery No. 1 and battery No. 2) on the metal plate 30 to simulate the contact between the battery casing and the battery pack box. The two decoated batteries are connected through the metal plate 30. In actual operation, the method to ensure that the two decoated batteries are in a conductive state can be: by measuring the resistance and voltage between the two decoated batteries to determine whether the two decoated batteries are conductive.

[0025] Step 3: Place the high-voltage module 40 on the wooden board 50 to simulate external high voltage. In actual operation, the high-voltage module 40 is placed separately from the two removed batteries to prevent the high-voltage module and the removed batteries from being grounded simultaneously and conducting. The negative terminal of the high-voltage module 40 is connected to the positive terminal of the first removed battery 10. A short-circuit tester is connected between the positive terminal of the high-voltage module 40 and the negative terminal of the second removed battery 20. The positive terminal of the short-circuit tester 60 is connected to the positive terminal of the high-voltage module 40, and the negative terminal of the short-circuit tester 60 is connected to the negative terminal of the second removed battery 20. By adjusting the short-circuit tester 60, the appropriate external short-circuit resistance value can be adjusted to control the current and switching of the circuit, so that a fixed voltage is applied across the two ends of the first removed battery 10 and the second removed battery 20 for withstand voltage breakdown verification.

[0026] Step 4: Connect the short-circuit tester 60 and adjust the voltage of the high-voltage module 40 to detect the withstand voltage breakdown value of the membrane-removed battery. When the current in the circuit exceeds the breakdown current or the membrane-removed battery experiences breakdown arcing (when the cover or casing of the membrane-removed battery experiences breakdown arcing, it indicates that the membrane-removed battery has experienced breakdown arcing), it indicates that two membrane-removed batteries have broken down. At this time, the voltage of the high-voltage module is determined as the withstand voltage breakdown value of the battery pack insulation abnormality. In this embodiment, the breakdown current is 10A, and the current in the circuit is less than 1A when no breakdown occurs.

[0027] In this invention, the individual cells in the battery pack can be either positive-electrode weakly conductive cells or non-positive-electrode weakly conductive cells, but their withstand voltage breakdown values ​​differ. A positive-electrode weakly conductive cell refers to a special battery design that achieves a weakly conductive connection between the positive electrode and the battery casing by introducing a high-resistance material in its structural design. A "weakly conductive pad" with specific resistance characteristics is placed between the positive electrode platen and the base plate (usually connected to the battery casing). Through this weakly conductive pad, a controllable high-resistance path is formed between the positive electrode and the battery casing, rather than direct conduction or complete insulation. Non-positive-electrode weakly conductive cells are conventional batteries without this design.

[0028] In a positive electrode weakly conductive battery, a relatively large weakly conductive resistance exists only at the positive electrode, i.e. Figure 3Each individual cell has a positive weak conducting plate 100 at its positive terminal. When one battery casing contacts the casing, the entire circuit is connected between the batteries through the contact between the casings. The resistance between the batteries is the resistance of the weak conducting plate. The connection between each battery occurs through the weak conducting plate connecting the casing to the next battery. Connection is only achieved when the weak conducting plate is broken down by high voltage. In non-positive weak conducting batteries, there is a large resistance insulating sheet at both the positive and negative terminals. Figure 3 Each individual cell has an insulating sheet 200 at its positive and negative terminals to prevent conductivity between the positive and negative terminals and the casing. When the battery casing is in contact with the housing, the conductivity between each cell is achieved through the insulating sheet between the positive and negative terminals. However, the insulation resistance between the positive and negative terminals is in parallel, and conductivity is only achieved when the insulating sheet is broken down by high voltage. The equivalent circuits under external high voltage are described below in principle for both positive and non-positive weakly conductive cells when insulation is abnormal: In this embodiment, the first individual cell in the battery pack is designated as the first cell to undergo membrane removal, and the nth individual cell is designated as the second cell to undergo membrane removal (where k=n). See [link to documentation]. Figure 4 When the battery with abnormal insulation in the battery pack is a positive electrode weakly conductive battery, the voltage between the positive electrode of battery No. 1 (without film removal) and the positive electrode of battery No. 2 (without film removal) is: V, In this embodiment, the voltage of each individual cell is... That is, the voltage between the positive terminal of cell No. 1 and cell No. 2 is... V. The resistance between the positive terminals of battery 1 and battery 2 is the sum of the resistance of the weak conductor at the positive terminal of battery 1 and battery 2.

[0029] See Figure 5 When the battery with insulation defects in the battery pack is a non-positive electrode weakly conductive battery, the voltage between the positive terminal of battery #1 (without film removal) and the negative terminal of battery #2 (without film removal) is: V, the voltage between the negative terminal of cell #1 (without film removal) and the positive terminal of cell #2 (without film removal) is... V, The voltage of each individual cell. For example, the voltage between the positive terminal of cell #1 and the negative terminal of cell #2 is... V, the voltage between the negative terminal of cell #1 (without film removal) and the positive terminal of cell #2 (without film removal) is... V.

[0030] The resistance between the positive terminal of battery #1 and the negative terminal of battery #2 is the sum of the resistances of the insulating sheets at the positive and negative terminals of battery #1 and battery #2, respectively. The resistance between the negative terminal of battery #1 and the positive terminal of battery #2 is the sum of the resistances of the insulating sheets at the negative and positive terminals of battery #2. The insulating sheets at the positive and negative terminals of battery #1 are connected in parallel, and the insulating sheets at the positive and negative terminals of battery #2 are also connected in parallel.

[0031] The breakdown voltage of the positive electrode weak conductor is much lower than that of the insulating sheet. Therefore, when the battery casing comes into contact with the battery box, the positive electrode weak conductor battery is more prone to module short circuits. For example, if the resistance of the positive electrode weak conductor in a positive electrode weak conductor battery is 210 ohms, its breakdown voltage is less than 12.4V. When there are more than 9 individual cells in the battery pack, a module short circuit may occur when the battery casing comes into contact with the battery box. Conversely, if the breakdown voltage of the insulating sheet in a non-positive electrode weak conductor battery is 300V, a module short circuit may only occur when there are more than 200 individual cells in the battery pack, and the battery casing comes into contact with the battery box.

[0032] This invention simulates the pressure conditions of a battery with abnormal insulation under high voltage. It can preliminarily determine the voltage at which the battery casing and battery pack housing will cause a short circuit after the outer insulating film is damaged. When no breakdown occurs, there are no obvious phenomena in the entire circuit, and the battery's resistance is normal. When a short circuit breakdown occurs, a large current will first appear in the circuit, followed by violent short-circuit arcing between the batteries.

[0033] Example 2 This embodiment provides a withstand voltage breakdown detection device for simulating battery pack insulation abnormalities, employing the withstand voltage breakdown detection method for simulating battery pack insulation abnormalities from Embodiment 1. See also... Figure 1 The testing device includes a first-stage battery 10 and a second-stage battery 20. Both batteries are located on a metal plate 30 and are electrically connected through the metal plate 30. The positive terminal of the first-stage battery 10 is connected to the negative terminal of a high-voltage module 40. The positive terminal of the high-voltage module 40 is connected in series with a short-circuit tester 60 and then connected to the negative terminal of the second-stage battery 20. The high-voltage module 40 is located on a wooden board 50. The metal plate 30 is a smooth, uncontaminated, pure conductive metal plate.

[0034] This invention uses two batteries with their outer insulating film removed, connected by a metal plate, and then connected to a short-circuit tester. After applying a stable external voltage, it can simulate whether a short circuit will occur when the battery casing's outer insulating film is damaged and comes into contact with the battery pack housing. The operation is simple and easy to implement.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting withstand voltage breakdown simulating insulation abnormalities in a battery pack, characterized in that: include: The insulating films of two individual cells are removed to obtain cell No. 1 and cell No. 2, which are used to simulate cells with abnormal insulation in the battery pack. Two de-coated batteries were placed on a metal plate to simulate the contact between the battery casing and the battery pack housing; Place the high-voltage module on a wooden board to simulate external high voltage. Connect the negative terminal of the high-voltage module to the positive terminal of the No. 1 membrane-removed battery. Connect a short-circuit tester between the positive terminal of the high-voltage module and the negative terminal of the No. 2 membrane-removed battery. Connect the short-circuit tester and adjust the voltage of the high-voltage module. When the current in the circuit exceeds the breakdown current or the de-filmed battery shows breakdown and arcing, the voltage of the high-voltage module is determined as the withstand voltage breakdown value of the battery pack insulation abnormality.

2. The method for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities according to claim 1, characterized in that: The battery pack consists of n individual cells connected in series, where n is an integer greater than 1. Cell No. 1 and Cell No. 2 simulate the 1st and kth individual cells in the battery pack, respectively, where 2 ≤ k ≤ n.

3. The method for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities according to claim 2, characterized in that: When the battery with insulation defects in the battery pack is a positive electrode weakly conductive battery, the voltage between the positive terminals of the No. 1 removed film battery and the No. 2 removed film battery is: V, The voltage of each individual cell.

4. The method for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities according to claim 3, characterized in that: A positive electrode weak conduction battery refers to a battery where weak conduction resistance exists only at the positive electrode. The resistance between the positive electrodes of the No. 1 and No. 2 defilmed batteries is the sum of the resistance of the weak conduction plate at the positive electrode of the No. 1 and No. 2 defilmed batteries.

5. The method for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities according to claim 2, characterized in that: When the battery with insulation defects in the battery pack is a non-positive electrode weakly conductive battery, the voltage between the positive terminal of battery number one (without film removal) and the negative terminal of battery number two (without film removal) is: V, the voltage between the negative terminal of cell #1 (without film removal) and the positive terminal of cell #2 (without film removal) is... V, The voltage of each individual cell.

6. The method for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities according to claim 5, characterized in that: A non-positive electrode weakly conductive battery refers to a battery where both the positive and negative electrodes have a large insulating sheet resistance. The resistance between the positive electrode of battery #1 and the negative electrode of battery #2 is the sum of the resistances of the insulating sheets at the positive and negative electrodes of battery #1 and battery #2, respectively. The resistance between the negative electrode of battery #1 and the positive electrode of battery #2 is the sum of the resistances of the insulating sheets at the negative and positive electrodes of battery #2. The insulating sheets at the positive and negative electrodes of battery #1 are connected in parallel, and the insulating sheets at the positive and negative electrodes of battery #2 are also connected in parallel.

7. The method for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities according to claim 1, characterized in that: Two decoction cells are connected by a metal plate. The connection between the two decoction cells is determined by measuring the resistance and voltage between them.

8. The method for detecting withstand voltage breakdown in simulated battery pack insulation abnormalities according to claim 1, characterized in that: The breakdown current is 10A, and the current in the circuit is less than 1A when no breakdown occurs.

9. A withstand voltage breakdown detection device for simulating insulation abnormalities in battery packs, employing the detection method described in any one of claims 1-8, characterized in that: It includes a No. 1 de-film battery and a No. 2 de-film battery. Both No. 1 and No. 2 de-film batteries are located on a metal plate and are connected through the metal plate. The positive terminal of the No. 1 de-film battery is connected to the negative terminal of the high-voltage module. The positive terminal of the high-voltage module is connected in series with a short-circuit tester and then connected to the negative terminal of the No. 2 de-film battery. The high-voltage module is located on a wooden board.

10. The withstand voltage breakdown detection device for simulating insulation abnormalities in a battery pack according to claim 9, characterized in that: The metal plate is a pure, conductive metal plate with a smooth, uncontaminated surface.

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