Liquid-cooled battery pack cell ground fault detector

Abstract

The application relates to a liquid-cooled battery PACK cell ground fault detector, which comprises a signal acquisition module, a processor unit and a display component, and the signal acquisition module and the display component are connected with the processor unit. The signal acquisition module is used for acquiring the total voltage, the positive electrode-to-ground voltage and the negative electrode-to-ground voltage of the liquid-cooled battery PACK; the processor unit calculates and processes the three types of voltage signals to obtain a fault result; and the display component visually presents the fault result. The detector can realize rapid detection and fault result output of the liquid-cooled battery PACK ground fault, and can complete the detection without large-scale disassembly of the battery pack, effectively solves the problems that the traditional detection method cannot locate the specific fault cell and the detection efficiency is low, and improves the accuracy, convenience and economy of the liquid-cooled battery PACK ground fault detection.

Description

Technical Field

[0001] This application relates to the field of power battery technology, and in particular to a cell grounding fault detection instrument in a liquid-cooled battery pack. Background Technology

[0002] With the widespread adoption of electric vehicles and energy storage systems, the safety of power battery packs is receiving increasing attention. During battery pack operation, insulation failure between the cells and the liquid cooling plate—a grounding fault—is a common and serious failure mode. For example, battery insulation failure is one of the main causes of battery module failure and can seriously threaten battery safety. Furthermore, EVE Energy's patent application addresses the issue of insulation failure at the venting points of the liquid cooling plate, and the liquid cooling plate is designed to prevent thermal runaway and avoid insulation failure.

[0003] Currently, the detection of such grounding faults mainly relies on two methods: The first is the traditional insulation resistance tester. While this tester provides high-precision measurement results and boasts advantages such as rapid response and portability, its main limitation is that it can only measure the overall insulation resistance of the battery pack to ground, failing to pinpoint the specific faulty cell. This forces maintenance personnel to expend considerable time and effort disassembling each cell individually for troubleshooting when the insulation resistance drops. The second method is BMS (Battery Management System) insulation detection. Its core objective is to monitor the insulation resistance between the high-voltage system (i.e., the positive and negative terminals of the battery pack) and (ground) in real time, ensuring that the resistance is above a safe threshold to prevent dangerous situations such as electric shock, short circuits, and fires. However, similarly, BMS insulation detection struggles to accurately locate the faulty cell; once an insulation fault occurs, the entire battery pack still needs to be disassembled for inspection.

[0004] In conclusion, there is an urgent need at maintenance sites for a dedicated testing instrument that is low-cost, easy to operate, and can quickly and accurately locate grounded cells, in order to replace inefficient manual troubleshooting methods and improve the safety and economy of maintenance. Summary of the Invention

[0005] Therefore, it is necessary to provide a detection instrument that can accurately locate the faulty battery cell to address the aforementioned technical problems.

[0006] In a first aspect, this application provides a cell grounding fault detection instrument for a liquid-cooled battery pack, comprising: a signal acquisition module, a processor unit, and a display component, wherein the signal acquisition module and the display component are both connected to the processor unit. The signal acquisition module is used to acquire the total voltage, positive terminal voltage to ground, and negative terminal voltage to ground of the liquid-cooled battery PACK. The processor unit calculates and processes the total voltage, positive-to-ground voltage, and negative-to-ground voltage to obtain the fault result; The display component displays the fault result.

[0007] In one specific embodiment, the processor calculates the total voltage, positive-to-ground voltage, and negative-to-ground voltage to obtain fault results, specifically including: The fault mode is determined based on the matching relationship between the total voltage and the positive-to-ground voltage and the negative-to-ground voltage. The fault modes include single-point grounding fault mode and multi-point grounding fault mode. After determining the fault mode, the fault location of the liquid-cooled battery PACK is calculated using the positive terminal to ground voltage and the negative terminal to ground voltage.

[0008] In one specific embodiment, the fault mode is determined based on the matching relationship between the total voltage and the positive-to-ground voltage and the negative-to-ground voltage, including: If the total voltage is equal to the sum of the positive-to-ground voltage and the negative-to-ground voltage, then the fault mode is a single-point grounding fault mode. If the total voltage is greater than the sum of the positive-to-ground voltage and the negative-to-ground voltage, then the fault mode is a multi-point grounding fault mode.

[0009] In one specific embodiment, after determining the fault mode, the fault location of the liquid-cooled battery PACK is calculated using the positive-to-ground voltage and the negative-to-ground voltage, including: If the fault mode is a single-point grounding fault mode, the following steps are performed to determine the fault location: calculate the voltage of a single cell based on the total voltage and the total number of cells in the liquid-cooled battery PACK; The location of the faulty cell in the liquid-cooled battery pack is calculated based on the negative electrode voltage to ground and the voltage of the individual cell.

[0010] In one specific embodiment, after determining the fault mode, the fault location of the liquid-cooled battery PACK is calculated using the positive-to-ground voltage and the negative-to-ground voltage, including: If the fault mode is a multi-point grounding fault, determine the fault location by following these steps: The voltage of a single battery cell is detected using a signal acquisition module; The starting location of the faulty cell is calculated based on the positive terminal-to-ground voltage and the individual cell voltage. The ending position of the faulty cell is calculated based on the negative electrode voltage to ground and the voltage of the individual cell; the terminal voltage to ground of the cells between the starting and ending positions is detected, and the location of the faulty cell in the liquid-cooled battery pack is determined based on the detection results.

[0011] In one specific embodiment, the processor unit is sequentially connected to a high-precision differential amplifier circuit, a signal isolation circuit, a digital-to-analog converter (ADC), a microcontroller (MCU), and an LED driver circuit. The signal acquisition module is connected to the high-precision differential amplifier circuit, and the LED driving circuit is connected to the display component.

[0012] In one specific embodiment, the digital-to-analog converter (ADC) is connected to a power management module, which is connected to a power supply.

[0013] In one specific embodiment, the signal acquisition module is sequentially connected to the signal acquisition component, the input protection circuit, and the analog switch circuit, with the analog switch circuit connected to the processor unit.

[0014] In one specific embodiment, the signal acquisition module is a test clamp, a test probe, or a probe.

[0015] In one specific embodiment, a Bluetooth module and / or a Wi-Fi module are provided, which can synchronize the acquired detection data and / or results to the target object, which includes mobile devices or the cloud.

[0016] This application discloses a liquid-cooled battery pack cell grounding fault detector, comprising a signal acquisition module, a processor unit, and a display unit, both connected to the processor unit. The signal acquisition module acquires the total voltage, positive-to-ground voltage, and negative-to-ground voltage of the liquid-cooled battery pack. The processor unit processes these three voltage signals to obtain the fault result, and the display unit visually displays the result. This detector, through modular hardware components and core voltage signal calculation and processing logic, achieves rapid detection and result output for liquid-cooled battery pack grounding faults. Detection can be completed without extensive disassembly of the battery pack, significantly reducing the operational difficulty and workload for maintenance personnel. Furthermore, the detector's voltage acquisition and calculation logic is applicable to series-connected liquid-cooled battery packs with different cell numbers and voltage levels, demonstrating strong versatility. The overall hardware architecture is simple and low-cost, facilitating large-scale deployment in after-sales service systems. It effectively solves the problems of traditional detection methods' inability to locate specific faulty cells and low troubleshooting efficiency, improving the accuracy, convenience, and economy of liquid-cooled battery pack grounding fault detection. Attached Figure Description

[0017] To clearly illustrate the embodiments or related technical solutions of this application, the accompanying drawings required in the description are briefly introduced below. Obviously, the following drawings are only some embodiments of this application, and those skilled in the art can obtain other related drawings based on them without creative effort.

[0018] Figure 1This is a schematic diagram of the internal circuit composition of a cell grounding fault detection tester in a liquid-cooled battery PACK in one embodiment; Figure 2 This is a schematic diagram of the external structure of a cell grounding fault detection and testing instrument in a liquid-cooled battery PACK in one embodiment. Figure 3 This is a schematic diagram of the working state of a cell grounding fault detection tester in a liquid-cooled battery PACK in one embodiment. Detailed Implementation

[0019] To clearly present the objectives, technical solutions, and advantages of this application, a detailed description is provided below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it.

[0020] This embodiment discloses a cell grounding fault detector for liquid-cooled battery packs, applicable to the detection of grounding faults in series-type liquid-cooled battery packs for electric vehicles and energy storage systems. It can quickly detect single-point grounding and multi-point grounding faults and output the results.

[0021] See Figure 1 , Figure 2 In this embodiment, the core components of the detector include a signal acquisition module 10, a processor unit 20, and a display component 30. The signal output terminal of the signal acquisition module 10 and the signal input terminal of the display component 30 are both electrically connected to the processor unit 20 in a bidirectional / unidirectional manner. To meet the requirements of portable on-site testing, this embodiment may also add a power management module 40 and a key input module 50 to the detector. The power management module 40 provides a stable DC power supply (e.g., 5V / 12V selectable) for each component. The key input module 50 is connected to the processor unit 20 and is used for operations such as preset detection parameters and triggering test commands.

[0022] The signal acquisition module includes a signal acquisition component, an input protection circuit, and an analog switch circuit connected in sequence. The analog switch circuit is connected to the processor unit. In this embodiment, the component can be a three-channel high-insulation test assembly, specifically including a red test probe (with metal test clamp), a black test probe (with metal test clamp), a yellow-green grounding test probe (with magnetic grounding connector), and an input protection circuit, an analog switch circuit, a high-precision differential amplifier circuit, and a signal isolation circuit corresponding to each probe. The red test probe is used to connect to the positive terminal (B+) of the liquid-cooled battery pack, the black test probe is used to connect to the negative terminal (B-) of the liquid-cooled battery pack, and the yellow-green grounding test probe is used to connect to the liquid-cooled plate / shell grounding point (GND) of the liquid-cooled battery pack. The input protection circuit can use a combination of a varistor and a current-limiting resistor to prevent overload of the measured voltage from damaging the internal circuitry. The analog switch circuit enables rapid switching and acquisition of the three-channel voltage signals. The high-precision differential amplifier circuit can amplify millivolt-level voltage signals to a range recognizable by the processor unit. The signal isolation circuit can use an opto-isolation chip with an isolation voltage ≥2500V, effectively preventing the detector from colliding with the battery pack. This will prevent electrical interference between the equipment and ensure the safety of the testing personnel.

[0023] During fault detection, the signal acquisition module acquires three types of voltage signals from the liquid-cooled battery pack. The signal acquisition module can accurately acquire the total voltage, positive-to-ground voltage, and negative-to-ground voltage of the liquid-cooled battery pack through synchronous acquisition mode. The specific implementation process is as follows: See Figure 3 The tester first clamps the metal test clamp of the red test probe to the B+ terminal of the liquid-cooled battery PACK, then clamps the metal test clamp of the black test probe to the B- terminal, and finally attaches the magnetic grounding connector of the yellow-green grounding test probe to the metal grounding point of the liquid-cooled plate. This completes the reliable electrical connection between the tester and the liquid-cooled battery PACK under test. The testing personnel send a data acquisition start command to the processor unit via the key input module. The processor unit then sends a synchronous trigger signal to the analog switch circuit of the signal acquisition module. At this time, the three analog switches close simultaneously, thereby realizing the total voltage (U) between B+ and B-. 总 The positive-to-ground voltage (U) between B+ and GND 正 The negative terminal voltage to ground between B- and GND (U) 负 Synchronous acquisition of data.

[0024] The three acquired analog voltage signals are processed sequentially through an input protection circuit, a high-precision differential amplifier circuit, and a signal isolation circuit before being transmitted to the ADC (Analog-to-Digital Converter) module of the processor unit to complete the analog-to-digital conversion. The converted digital voltage signals are temporarily stored in the processor unit's temporary data storage area, awaiting subsequent calculations. In this embodiment, the voltage acquisition range of the signal acquisition module is 0-1000V, with an acquisition accuracy of ±0.1% FS, and it can be adapted to series-connected liquid-cooled battery packs (10-200 cells in series) composed of 3.2V / 3.7V and other different specifications of cells.

[0025] In terms of the processor unit, this embodiment uses a 32-bit microcontroller (MCU, model STM32F407) as the core. This MCU integrates a high-speed ADC digital-to-analog converter module (12-bit conversion accuracy, 1MSPS conversion rate), a data storage unit, and an algorithm processing unit. The MCU's ADC acquisition terminal is connected to the output terminal of the signal isolation circuit of the signal acquisition module, and its function is to receive the analog voltage signal and convert it into a digital signal. The MCU's instruction output terminal is connected to the display component and the key input module respectively, thereby realizing data interaction and instruction response. In addition, the MCU has a ground fault calculation and processing algorithm embedded in it, which can provide logical support for obtaining fault results.

[0026] The processor unit processes three types of voltage signals to obtain fault results. Specifically, when the processor unit receives the converted digital voltage signal, it invokes its internally programmed ground fault calculation and processing algorithm, targeting U... 总 U 正 U 负 By performing logical judgments and numerical calculations, the final fault result, including the fault type and the location / range of the faulty cell, is obtained. The specific calculation process is as follows: In the parameter preset call stage: the processor unit first reads the total number of series-connected cells (N) of the liquid-cooled battery PACK preset via the button input module, and then calls the parameter preset according to the formula U cell = U 总 / N calculates the nominal voltage (U) of each individual cell in the battery pack. cell ), and U cell The value is temporarily stored for later use in fault location calculation; Fault type determination stage: The processor unit will check the U 正 + U 负 The calculated value and U 总 By comparing the fault types, the fault type can be determined. If**|U 正 + U 负 - U总 |≤0.5% U 总 If the values ​​are equal within the error range, it is determined to be a single-point grounding fault. If U 正 + U 负 < U 总 If so, it is determined to be a multi-point grounding fault; Fault Result Calculation: For single-point grounding faults: the processor unit uses the formula P=round (U 负 / U cell ) Calculate the location number of the faulty cell (P, counting from the negative terminal of the battery pack), and finally generate the fault result "single-point grounding fault, cell P is grounded from the negative terminal"; For multi-point grounding faults: The processor unit first generates the basic fault result of "multi-point grounding fault", and then calculates the result according to the formula P1=U. 正 / U cell + 1, PN=U 负 / U cell The starting position (P1) and ending position (PN) of the faulty cell are calculated respectively, and the fault result of "multi-point grounding fault, the range of faulty cells is from cell number P1 to cell number PN" is finally generated. Fault result storage: The processor unit stores the calculated fault results in a non-volatile data storage area, which can support subsequent data playback and uploading. At the same time, it converts the digital signal of the fault result into a drive signal that can be recognized by the display component and transmits it to the display component.

[0027] Display Components: In this embodiment, a 2.4-inch TFT LCD screen with a resolution of 320*240 can be used as the display component, supporting various forms of fault result display, including numbers, text, and icons. The screen is connected to the processor unit via the SPI communication protocol, with a data transmission rate of no less than 1Mbps, ensuring real-time display of fault results. Simultaneously, the screen surface is covered with an anti-scratch and anti-reflective film to meet the visual requirements of outdoor maintenance sites.

[0028] The display component can display fault results in real time: upon receiving a fault result drive signal from the processor unit, it will present the fault results in real time in clear and intuitive text and numerical form according to a preset display interface template. The specific display rules are as follows: For single-point grounding faults, the main interface of the display screen will show "Detection result: Single-point grounding fault" and "Faulty cell: No. P from the negative terminal" (P is the calculated specific number) in a prominent position below. For multi-point grounding faults, the main interface of the display screen will show "Detection Result: Multi-point Grounding Fault," with "Fault Range: Cells P1 to PN" displayed below (P1 and PN are calculated numbers). In this embodiment, the fault result refresh time of the display component does not exceed 0.5 seconds, achieving zero-delay display of the detection results. Furthermore, the display screen supports backlight adjustment, meeting the needs of use in dimly lit repair environments.

[0029] In this embodiment, the detector can also be expanded to include functions such as uploading voltage data and fault results via Bluetooth / Wi-Fi, and local storage and playback. The processor unit is externally connected to a Bluetooth / Wi-Fi module (models HC-05 and ESP8266 respectively), enabling U... 总 U 正 U 负 Data such as fault results are uploaded to mobile terminals (phones / tablets) or cloud servers to achieve remote management of detection data.

[0030] In one optional embodiment, the processor unit's computational processing logic mainly includes: First, by controlling the total voltage (U... 总 ) and positive terminal to ground voltage (U 正 ), negative electrode to ground voltage (U) 负 The numerical matching relationship is used to determine the fault mode, which is divided into two categories: single-point grounding and multi-point grounding. The second step, after determining the specific fault mode, is to select U accordingly. 正 U 负 As a core calculation parameter, the fault location of the liquid-cooled battery pack is calculated by combining the relevant voltage values ​​of the battery cell, avoiding the positioning error caused by indiscriminate calculation, and achieving accurate fault location.

[0031] Optionally, the processor unit completes U 总 U 正 U 负 After signal acquisition and analog-to-digital conversion, the fault mode determination subroutine is first activated. This subroutine uses a preset numerical matching determination algorithm to determine the fault mode of U. 正 with U 负 After adding the calculated values, add them to U 总 A comparison is performed to determine the unique fault mode result. Once the fault mode is determined, the processor unit automatically calls the corresponding fault location calculation subroutine. In this subroutine, only the U values ​​matching the current fault mode are extracted. 正 U 负As a calculation parameter, interference from other irrelevant parameters is shielded. Combined with cell voltage-related data, the fault location is calculated. Finally, the fault mode and fault location information are integrated to form a complete fault diagnosis result. In this embodiment, the algorithm program built into the processor unit adopts a modular design, with the fault mode determination subroutine and the corresponding location calculation subroutine for each fault mode being independent of each other. Firmware upgrades can optimize the determination logic and calculation formulas without changing the hardware architecture. Simultaneously, the processor unit records data on each matching relationship and calculation process and stores it in a non-volatile memory area for subsequent fault tracing and data analysis.

[0032] In one optional embodiment, a fault mode determination rule is provided, which clarifies the quantitative determination criteria for single-point grounding and multi-point grounding fault modes: using U 总 Based on U 总 equal to U 正 with U 负 If the sum of the values ​​is equal to the sum of the values ​​of the two points, then the fault is determined to be a single-point grounding fault mode; if U 总 Greater than U 正 with U 负 The sum of these values ​​indicates a multi-point grounding fault mode. This criterion is based on the circuit characteristics of liquid-cooled battery pack grounding faults. In the case of a single-point grounding, the battery pack circuit has no additional voltage loss, U 正 + U 负 with U 总 Completely consistent; with multiple grounding points, the circuit has multiple leakage currents, which will generate additional voltage loss, causing U 正 + U 负 The value is less than U 总 .

[0033] In another optional embodiment, considering the voltage acquisition errors that exist in the actual detection process (such as line loss and detection element accuracy deviation), this embodiment adds an error tolerance to the judgment criteria to improve the accuracy and practicality of fault mode judgment. The specific judgment rules are as follows: The voltage acquisition error tolerance is set to ±0.5% U. 总 **(This value can be adjusted in the range of 0.1% to 1% via the button input module of the detector to adapt to detection scenarios with different accuracy requirements). If **|(U positive + U negative) - U total| ≤ error tolerance**, then it is determined to be a single-point grounding fault mode, and the processor unit calls the single-point grounding fault location calculation subroutine; If U 正 + U 负 < U 总- If the error tolerance is within the acceptable range, the fault is determined to be a multi-point grounding fault mode. In this case, the processor unit calls the multi-point grounding fault location calculation subroutine. If U appears 正 + U 负 > U 总 In cases of abnormal error tolerance, the processor unit determines it as a detection anomaly and subsequently outputs a "Voltage acquisition abnormality, please check test connection" message on the display, while simultaneously triggering a buzzer alarm to remind testing personnel to check for issues such as the test probe connection and battery pack status. In this embodiment, the processor unit's decision-making response time is ≤10ms, which meets the standard for detector response time, enabling rapid fault mode determination and satisfying the needs of rapid on-site testing.

[0034] In one optional embodiment, a fault location calculation method is provided under a single-point grounding fault mode. This fault location calculation includes two core steps: First, the voltage of a single cell (Utotal) is calculated by combining Utotal with the total number of cells (N) in the liquid-cooled battery pack. cell The second step is to use U... 负 with U cell The exact location of the faulty cell is calculated using the ratio of the voltages of the two cells. This calculation method is based on the voltage division characteristics of a series-connected battery pack. When grounded at a single point, the voltage between the negative terminal and ground is the sum of the voltages of all cells from the faulty cell to the negative terminal. Therefore, the location is determined by the ratio of the voltages of the two cells. 负 with U cell The ratio can accurately locate faulty battery cells.

[0035] This implementation method, based on the actual needs of on-site testing, refines the fault location calculation steps under the single-point grounding fault mode and adds a result verification step to improve the positioning accuracy, as detailed below: Total number of cells: The processor unit first reads the total number of series cells N of the liquid-cooled battery PACK preset by the tester through the key input module (the input range of N is 10-200 cells, which is suitable for different specifications of battery packs for passenger cars, commercial vehicles and energy storage systems). Single cell voltage calculation: The processor unit is based on formula U cell = U 总 / N calculates the nominal voltage of a single battery cell, retains 3 decimal places, and temporarily stores it in the temporary data area; Faulty cell location calculation: The processor unit calculates the location using the formula P = round (U_negative / U_f) cell Calculate the faulty cell location number, where round is the rounding function, and P is the cell number counting from the negative terminal of the liquid-cooled battery PACK, with a value of a positive integer; Result verification: The processor unit automatically verifies the range of P values. If 1 ≤ P ≤ N, the calculation result is deemed valid, and a fault result of "single-point grounding fault, grounding fault of cell P starting from the negative terminal" is generated. If P < 1 or if P > N, the calculation result is deemed abnormal. At this time, the display component outputs the prompt "fault location calculation abnormal, please retest" and automatically triggers the operation of re-acquiring voltage and recalculating. Regarding output, once the verification passes, the processor unit transmits the fault location result to the display unit for intuitive display. Simultaneously, the U... 总 U 正 U 负 、N、U cell Data such as P are stored locally to support subsequent data playback. Implementation example: The battery pack under test has N=104 cells. Data collected include Utotal = 341.0V, Upositive = 157.2V, and Unegative = 183.5V. Calculations show Ucell≈3.279V, P=round(183.5 / 3.279)≈56. Verification shows 56 is within the range of 1-104. The final output reads: "Based on the single-point grounding fault detection and location method for cascaded H-bridge battery energy storage systems, after calculation and verification, the fault point is determined to be cell number 56 starting from the negative terminal."

[0036] In one embodiment, a fault location calculation method is provided under a multi-point grounding fault mode. The core multi-step process for fault location calculation in this mode is as follows: First, the voltage of a single battery cell is additionally detected through a signal acquisition module; then, the voltage is calculated separately through U... 正 U 负 With the voltage U of a single battery cell cell The ratio is used to calculate the start and end positions of the faulty cell; finally, the pole-to-ground resistance of the cells within this range is detected, thereby achieving precise location of the faulty cell. For multi-point grounding faults in power transformer cores, this method first narrows down the investigation scope, and then uses resistance detection technology for precise location, effectively solving the technical problems of unclear voltage loss and fault location.

[0037] In another optional embodiment, the fault location calculation and detection steps under the multi-point grounding fault mode are refined, clarifying the operational requirements, calculation standards, and judgment rules for each step to adapt to the needs of portable on-site detection, as follows: Mode prompt: When the processor unit determines that the multi-point grounding fault mode is detected, it will immediately output the prompt message "Multi-point grounding fault mode, please measure the voltage of individual cells" through the display component, and at the same time the buzzer will emit a short beep to remind the test personnel to perform the next operation. Single cell voltage acquisition: The tester uses a high-precision signal acquisition module to connect the red and black test probes to the positive and negative electrode posts of a normal cell in the liquid-cooled battery PACK. By pressing the "single cell test" button on the tester, the module uses a high-precision single cell voltage acquisition channel (range 0 - 5V, accuracy ±0.001V) to acquire the actual voltage U of the single cell cell for acquisition. After the acquisition is completed, the data is automatically transmitted to the processor unit, ensuring the high precision and reliability of the voltage data.

[0038] Calculation of the range of faulty cells: The processor unit calculates the starting position of the faulty cell according to the formula P1 = int (U 正 / U cell ) + 1 (where int() is the floor function); Calculates the ending position of the faulty cell according to the formula PN = round (U 负 / U cell ); The processor unit verifies the value range of P1 and PN. If 1 ≤ P1 < PN ≤ N, it determines that the range is valid and outputs a prompt through the display component: "Insulation fault of cells between No. P1 - PN. Please measure the resistance between the electrode post and the ground respectively"; if the range is invalid, it outputs a prompt: "Abnormal range calculation. Please re-measure the single cell voltage".

[0039] Detection of the resistance between the electrode post and the ground: The tester keeps the yellow-green grounding probe of the signal acquisition module connected to the grounding point of the liquid-cooled plate, connects the red test probe to the positive and negative electrode posts of the cells numbered P1 - PN in turn, leaves the black test probe suspended, and presses the "resistance test" button; The high-resistance detection module of the signal acquisition module (range 1MΩ - 1000MΩ, accuracy ±1%) acquires the resistance value R between the electrode post of each cell and the ground and transmits it to the processor unit; The processor unit presets the insulation resistance threshold to 10MΩ (this threshold can be adjusted between 5MΩ - 20MΩ through buttons). If R < 10MΩ, it determines that there is an insulation fault in this cell, and the display component outputs "Insulation fault of No. X cell"; if R ≥ 10MΩ, it determines that the insulation of this cell is normal, and the display component outputs "Insulation normal of No. X cell"; Result summary: After all the cells numbered P1 - PN are detected, the processor unit automatically summarizes the serial numbers of all faulty cells, displays them in a list through the display component, and at the same time stores all the detection data and fault results and supports Bluetooth / Wi-Fi upload; Implementation example: U 正 = 80V, U 负 = 90V, Ucell =3.2V, calculate P1=int (80 / 3.2)+1=26, PN=round (90 / 3.2)=28, check cells 26-28. If the resistance of cell 27 to ground is R=5MΩ<10MΩ, and the others are 15MΩ≥10MΩ, then the final output is "Multi-point grounding fault, faulty cell: No. 27".

[0040] In one optional embodiment, the processor unit is designed with a high-precision differential amplifier circuit, which possesses excellent common-mode rejection ratio (CMRR) to ensure high-precision signal processing by the signal acquisition module. Furthermore, a signal isolation circuit, a digital-to-analog converter (ADC), a microcontroller (MCU), and an LED driver circuit are connected in series to ensure stable signal transmission and accurate display. This hardware architecture amplifies, isolates, converts, and processes voltage signals, guaranteeing the accuracy and security of signal processing.

[0041] In another specific embodiment of this application, the selection, function, parameters, and connection method of each hardware module of the processor unit are further detailed to ensure the practicality and stability of the hardware architecture. High-precision differential amplifier circuit Selection: The AD620 instrumentation amplifier with a common-mode rejection ratio (CMRR) ≥ 100 dB can be used; Function: Differential amplification of the weak voltage analog signal transmitted by the signal acquisition module, with adjustable amplification factor (1-1000 times), amplifying the millivolt-level signal to a volt-level signal that can be recognized by the digital-to-analog converter (ADC); Connection: The input terminal is connected to the output terminal of the analog switch circuit of the signal acquisition module via a shielded wire, and the output terminal is connected to the input terminal of the signal isolation circuit. The power supply voltage is ±5V.

[0042] Signal isolation circuit Selection: We recommend using the 6N137 opto-isolation chip, which has an isolation voltage ≥2500V AC; Function: To achieve electrical isolation between the internal circuitry of the detector and the high-voltage circuitry of the liquid-cooled battery pack, preventing high voltage from entering the detector and causing damage to components, while also avoiding electromagnetic interference from the detector to the battery pack BMS system, thus ensuring the safety of testing personnel and equipment; Connections: The input terminal is connected to the output terminal of the high-precision differential amplifier circuit, and the output terminal is connected to the input terminal of the digital-to-analog converter (ADC).

[0043] Digital-to-analog converter (ADC) Selection: The recommended choice is the 12-bit high-speed ADC chip ADS8364, which has a conversion rate of 1MSPS; Function: Converts amplified and isolated analog voltage signals into digital signals with a conversion accuracy of ±1LSB; Connection: The input terminal is connected to the output terminal of the signal isolation circuit, and the output terminal is connected to the microcontroller (MCU) via the SPI serial communication interface to achieve high-speed transmission of digital signals.

[0044] Microcontroller MCU Selection: We recommend using the 32-bit embedded MCU STM32F407ZGT6, which has 1MB of built-in Flash and 192KB of RAM; Function: As the core of the processor unit, it has a built-in fault detection algorithm, which can perform digital signal processing, fault mode determination and fault location calculation, and can also receive key input commands to control the working status of each module. Connections: Connects to the ADC via the SPI interface, connects to the LED driver circuit and key input module via I / O ports, and has built-in timers, serial ports and other peripherals to support expansion functions.

[0045] LED driver circuit Selection: The TM1628 driver chip can be used, which supports driving multi-segment digital tubes and LCD screens; Function: It can amplify the digital signal of fault result output by microcontroller (MCU) to drive the display component to work normally and effectively improve the stability of the display signal; Connection: The input terminal connects to the I / O port of the microcontroller (MCU), and the output terminal connects to the drive interface of the display component, while also providing operating voltage to the display component.

[0046] In terms of overall connectivity, all circuit modules can be surface-mounted on PCBs. The layout follows the principle of separating analog and digital circuits to reduce electromagnetic interference. Furthermore, the PCBs undergo three-proof treatment (moisture-proof, mildew-proof, and salt spray-proof) to enhance the instrument's adaptability to harsh maintenance environments such as outdoor and humid conditions.

[0047] In one optional embodiment, the digital-to-analog converter (ADC) is connected to a power management module, which provides power to the entire processor unit and all electrical components of the detector; it is the energy core of the detector hardware system. The power management module is configured to provide voltage regulation, filtering, and overcurrent protection for the input power supply, ensuring stable operation of each hardware module at its rated voltage.

[0048] In another specific embodiment, the selection, function, power supply method, and protection mechanism of the power management module are detailed, and its power supply connection relationship with the digital-to-analog converter (ADC) and various hardware modules is clarified to adapt to the power supply requirements of portable testing, as follows: Power management module selection: The MP2307 integrated power management chip can be used, along with external filtering, voltage regulation and protection circuits, to form a complete power management module that supports wide voltage input.

[0049] Power supply: This detector supports dual power supply modes to meet the needs of different testing scenarios. Built-in rechargeable lithium battery power supply: It can use a 3.7V / 5000mAh lithium-ion battery, which is boosted to 5V and ±12V by the power management module to power the hardware modules. It can work continuously for no less than 8 hours when fully charged, and supports USB Type-C interface fast charging. External DC power supply: Supports 9V-24V DC power input, which is regulated to the rated operating voltage of each hardware module through the power management module, suitable for fixed testing scenarios in the workshop.

[0050] Connection with the ADC: The power management module provides an independent 5V reference voltage and operating voltage for the ADC. A low-noise voltage regulator circuit can be used to reduce the impact of power supply ripple on the ADC conversion accuracy and ensure the accuracy of voltage signal conversion. At the same time, a 0.5A self-resetting fuse is connected in series in the power supply circuit to prevent the ADC chip from being damaged by overcurrent.

[0051] Overall power supply and protection mechanism: The power management module provides tiered power supply for each hardware module of the detector. Analog circuits (including high-precision differential amplifier circuits and signal isolation circuits): provide a clean power supply of ±12V to effectively reduce signal interference; Digital circuits (including ADC, MCU, and LED driver circuits): provide a stable 5V power supply; Peripherals (including display components, key input modules, Bluetooth / Wi-Fi modules): provide optional 3.3V or 5V power supply; Protection Mechanism: The power management module has built-in overvoltage, overcurrent, overtemperature, and undervoltage protection functions. When the input voltage is abnormal, a short circuit occurs, the device temperature is too high (≥60℃), or the lithium battery voltage is low (≤3.0V), the module will automatically cut off the power supply to protect the hardware module and output the corresponding fault prompt through the display component.

[0052] Power management display: The display unit shows the current power supply mode and remaining power in real time. When powered by lithium battery, it displays the power percentage (10%-100%). When the voltage is low, it displays "Insufficient power, please charge" and triggers an intermittent buzzer alarm.

[0053] In one optional embodiment, the signal acquisition module consists of a signal acquisition component, an input protection circuit, and an analog switch circuit connected in series. The analog switch circuit is connected to a high-precision differential amplifier circuit in the processor unit. This hardware architecture can safely acquire voltage signals and implement overload protection and channel switching functions, thereby ensuring the safety and flexibility of the signal acquisition process.

[0054] In another embodiment, the functions, parameters, selection, and operating modes of each hardware module of the signal acquisition module are detailed, and the switching logic of the three-channel signal acquisition is clarified to adapt to the synchronous or sequential acquisition requirements of total voltage and voltage to ground, as follows: Signal acquisition component Function: Directly connect to the positive terminal, negative terminal, and liquid cooling plate grounding point of the liquid-cooled battery PACK to obtain the raw voltage signal; Selection: The test end can be made of high-conductivity copper alloy material, with nickel plating on the surface to prevent oxidation, and is equipped with high-temperature resistant, high-insulation-level (≥10kV) silicone wire with a length of 2m to meet the operation distance requirements of on-site testing.

[0055] Input protection circuit Selection: A composite overvoltage and overcurrent protection circuit consisting of a varistor (MOV14D471K), a current-limiting resistor (100kΩ / 2W), and a diode (1N4007) is adopted; Function: When the voltage being measured exceeds the acquisition range of the detector (>1000V) or a momentary surge voltage occurs, the varistor will quickly break down and conduct, the current-limiting resistor will limit the short-circuit current, and the diode will prevent the current from reversing, thereby protecting the subsequent analog switching circuit, processor unit and other precision components from damage. Connection method: The input terminal is connected to the signal acquisition component, and the output terminal corresponds one-to-one with the input terminal of the analog switch circuit. Each acquisition channel is equipped with an independent input protection circuit to achieve individual protection.

[0056] Analog switch circuit Selection: The CD4051 high-speed CMOS analog switch chip can be used. A single chip supports 8-channel switching. This detector is configured with 3 three-channel, corresponding to B+, B-, and GND for voltage acquisition respectively. Function: Enables switching between synchronous acquisition and fast sequential acquisition modes for three-channel voltage signals, and controls the on / off state of signal acquisition. This function is controlled by the I / O port of the microcontroller MCU, and the switching response time is ≤1μs. Connection method: The three input terminals are respectively connected to the output terminals of the three input protection circuits, and the output terminals are combined and connected to the input terminal of the high-precision differential amplifier circuit of the processor unit; Data Acquisition Mode Switching: The detector supports two data acquisition modes, which can be switched using buttons: Synchronous acquisition mode: The microcontroller (MCU) controls the simultaneous closure of three channels of the analog switch circuit to achieve synchronous acquisition of Utotal, Upositive, and Unegative, ensuring no phase error and minimal crosstalk between multiple channels, effectively avoiding acquisition errors caused by battery pack voltage fluctuations, and is suitable for high-precision detection scenarios.

[0057] Fast Sequential Acquisition Mode: The microcontroller (MCU) enables rapid sequential closure of three channels through precise control, with an acquisition interval of ≤10μs, thereby quickly and sequentially acquiring voltage signals. This low-power sampling technology not only improves data acquisition efficiency but also significantly reduces circuit power consumption, making it particularly suitable for detection scenarios requiring long-term operation and sensitive to power consumption.

[0058] In one optional embodiment, the signal acquisition module can be selected from three physical forms: test clamp, test probe, and probe, to adapt to different terminal structures, installation spaces, and other field testing conditions of liquid-cooled battery PACKs, thereby improving the versatility and ease of operation of the tester.

[0059] In another embodiment, the structure, applicable scenarios, and operational characteristics of the three physical forms are described in detail. These three forms adopt a replaceable design, and the signal interface of the detector uses a universal aviation connector, enabling quick disassembly and replacement without altering the internal circuitry, as detailed below: Test clamp Structure: It can adopt ratchet-type insulation test clamps with anti-slip serrated jaws, a maximum opening diameter of 30mm, and the body is covered with high insulation level (≥10kV) PVC material. The handle has anti-slip texture, and the tail connects to the tester cable via an aviation plug. Applicable scenarios: Suitable for liquid-cooled battery packs with bolt-type terminals for positive and negative terminals, and where the terminals are spaced far apart and there is sufficient operating space, such as large battery packs for energy storage systems and commercial vehicle battery packs; Operational features: The ratchet design enables hand-held clamping, eliminating the need for continuous gripping by the operator and effectively reducing operational intensity. Simultaneously, the large clamping contact area ensures stable signal acquisition.

[0060] Test probe Structure: It can be equipped with a pen-type insulation test probe with a gold-plated probe tip (2mm in diameter), a telescopic insulating rod body (telescopic range 15cm-50cm), an aviation plug at the tail, and a non-slip pen cap; Applicable scenarios: Suitable for scenarios where liquid-cooled battery packs have small terminals, dense wiring, and narrow operating space, such as power battery packs for passenger vehicles and small energy storage battery packs; Operating features: The telescopic insulating rod can reach into narrow spaces to carry out testing work; the gold-plated probe has good conductivity and is not easy to oxidize, which can ensure the accuracy of weak signal acquisition; the pen design is flexible to operate and facilitates precise single-point contact.

[0061] probe Structure: A needle-type insulated probe can be selected. The probe is made of hard alloy material (1mm in diameter and 5cm in length). The needle shaft is wrapped with polytetrafluoroethylene high insulation material. The tail is connected to the aviation plug through a flexible shielded wire and is equipped with a handheld fixing base. Applicable scenarios: Suitable for liquid-cooled battery PACK terminals that are covered by protective covers, requiring the protective layer to be pierced for testing, or for fine-grained scenarios of terminal-to-ground resistance testing; Operating features: The hard alloy probe has high hardness and is not easy to bend, which can easily pierce the insulation protection layer. The flexible shielding wire can flexibly adjust the detection angle. The handheld fixing base can ensure the operation safety of the testing personnel and prevent the probe from slipping.

[0062] Universal connection design: All three physical tail configurations can utilize a low-temperature 7-pin aviation connector for foolproof connection to the detector's signal cable. The connector features a waterproof sealing ring, achieving an IP65 protection rating, ensuring stability and reliability in harsh outdoor environments such as rain and humidity.

[0063] In one optional embodiment, the detector may be equipped with a Bluetooth module and / or a Wi-Fi module to enable synchronous transmission of detection data and fault results. The target objects of the transmission include mobile devices (phones, tablets) and cloud servers, breaking the limitation of local storage of the detector and realizing remote management, real-time sharing and big data analysis of detection data.

[0064] In another optional embodiment, the selection, functional characteristics, transmission methods, data synchronization content, and interaction methods of the target object for the Bluetooth and Wi-Fi modules are further detailed to achieve seamless transmission of detection data. The specific implementation details are as follows: Module selection and connection Bluetooth module: Can use Bluetooth 5.0 module HC-08, transmission distance ≤100m, low power consumption, connects to microcontroller MCU via UART serial port, supports Bluetooth pass-through mode; Wi-Fi module: Can use ESP8266 wireless module, supports 802.11b / g / n protocol, transmission distance ≤50m (indoor), connects to microcontroller MCU via SPI interface, supports STA / AP dual mode; Regarding the module layout, these two modules are integrated on the PCB board of the detector. They are optional modules that can be configured individually or simultaneously according to customer needs, and will not affect the core functions of the detector.

[0065] Data transmission content: The content synchronized by the detector via Bluetooth / Wi-Fi module includes raw detection data and fault result data, specifically: U total, U positive, U negative, total number of cells N, individual cell voltage Ucell, fault mode, location of faulty cell / range involved, terminal resistance to ground value, detection time, detector number, etc. All data are transmitted in JSON format, which facilitates subsequent parsing and storage.

[0066] Sync with mobile devices A dedicated app has been developed for mobile devices, supporting both Android and iOS systems. When the detector is powered on, it automatically enables Bluetooth / Wi-Fi broadcasting, allowing mobile devices to pair and connect with a single click via the app, without requiring a password. Once the connection is successful, the test data and fault results will be synchronized to the app in real time. The app supports local data storage, chart display, historical record query, and fault report generation (PDF format). Testers can send fault reports to the maintenance team through the app, thereby achieving remote collaboration.

[0067] Synchronization with the cloud Once the Wi-Fi module successfully connects to the on-site wireless network, the detector will automatically upload the detection data to a dedicated cloud server. This server can be an Alibaba Cloud / Tencent Cloud server, which has functions such as data encryption and disaster recovery backup. The cloud server supports multi-terminal access (computers, tablets, and mobile phones). Through big data analytics, it can identify key information such as the high-incidence locations, failure rates, and geographical distribution of battery pack grounding faults. For example, based on the failure case analysis of the Leapmotor T03 battery pack, fault codes and causes can be identified, enabling troubleshooting and repair. Furthermore, by combining market failure statistics and classifications, such as the 53 publicly reported failure cases in 2022, and suggestions for improving power battery safety, it can provide strong data support for battery pack design optimization and after-sales maintenance.

[0068] The cloud server has a fault warning function. Once it detects that the insulation resistance of the battery pack is close to the threshold, it will automatically send an SMS / APP warning to the administrator to enable early maintenance.

[0069] Data transmission protection: All transmitted data is encrypted using the AES-128 encryption algorithm, effectively preventing data leakage and tampering. Simultaneously, the detector supports offline storage; when there is no network or Bluetooth connection, the test data is automatically stored locally and automatically retransmitted upon reconnection, ensuring no data loss.

[0070] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by computer program instructions to related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it includes the processes of the above method embodiments. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory includes random access memory (RAM) and external cache memory, etc. It should be noted that RAM is not limited to a specific form; it can be various types such as Static Random Access Memory (SRAM) and Dynamic Random Access Memory (DRAM). The databases involved in the embodiments of this application include at least one of relational databases and non-relational databases. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0071] The technical features in the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations are described, but as long as the combination is not contradictory, it falls within the scope of this application.

[0072] The above embodiments only present several implementation methods of this application. Although the descriptions are detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A cell grounding fault detection instrument for liquid-cooled battery packs, characterized in that, It includes a signal acquisition module, a processor unit, and a display component; wherein, both the signal acquisition module and the display component are connected to the processor unit. The signal acquisition module is used to acquire the total voltage, positive terminal voltage to ground, and negative terminal voltage to ground of the liquid-cooled battery PACK. The processor unit calculates and processes the total voltage, positive-to-ground voltage, and negative-to-ground voltage to obtain the fault result; The display component displays the fault result.

2. The fault detector according to claim 1, characterized in that, The processor unit calculates and processes the total voltage, positive-to-ground voltage, and negative-to-ground voltage to obtain fault results, specifically including: The fault mode is determined based on the matching relationship between the total voltage and the positive-to-ground voltage and the negative-to-ground voltage. The fault modes include single-point grounding fault mode and multi-point grounding fault mode. After determining the fault mode, the fault location of the liquid-cooled battery pack is calculated using the positive-to-ground voltage and the negative-to-ground voltage.

3. The fault detector according to claim 2, characterized in that, The fault mode is determined based on the matching relationship between the total voltage and the positive-to-ground voltage and the negative-to-ground voltage, including: If the total voltage is equal to the sum of the positive-to-ground voltage and the negative-to-ground voltage, then the fault mode is a single-point grounding fault mode. If the total voltage is greater than the sum of the positive-to-ground voltage and the negative-to-ground voltage, then the fault mode is a multi-point grounding fault mode.

4. The fault detector according to claim 2, characterized in that, After determining the fault mode, the fault location of the liquid-cooled battery pack is calculated using the positive-to-ground voltage and the negative-to-ground voltage, including: If the fault mode is a single-point grounding fault mode, the following steps are performed to determine the fault location: calculate the voltage of a single cell based on the total voltage and the total number of cells in the liquid-cooled battery PACK; The location of the faulty cell in the liquid-cooled battery pack is calculated based on the negative electrode voltage to ground and the voltage of the individual cell.

5. The fault detector according to claim 2, characterized in that, After determining the fault mode, the fault location of the liquid-cooled battery pack is calculated using the positive-to-ground voltage and the negative-to-ground voltage, including: If the fault mode is a multi-point grounding fault mode, determine the fault location by following these steps: The voltage of a single battery cell is detected using a signal acquisition module; The starting location of the faulty cell is calculated based on the positive terminal-to-ground voltage and the individual cell voltage. The ending position of the faulty cell is calculated based on the negative electrode voltage to ground and the voltage of the individual cell; the terminal voltage to ground of the cells between the starting and ending positions is detected, and the location of the faulty cell in the liquid-cooled battery pack is determined based on the detection results.

6. The fault detector according to claim 1, characterized in that, The processor unit includes a high-precision differential amplifier circuit, a signal isolation circuit, a digital-to-analog converter (ADC), a microcontroller (MCU), and an LED driver circuit connected in sequence. The signal acquisition module is connected to the high-precision differential amplifier circuit, and the LED driving circuit is connected to the display component.

7. The fault detector according to claim 6, characterized in that, The digital-to-analog converter (ADC) is also connected to a power management module, which is connected to a power supply.

8. The fault detector according to claim 1, characterized in that, The signal acquisition module includes a signal acquisition component, an input protection circuit, and an analog switch circuit connected in sequence. The analog switch circuit is connected to the processor unit.

9. The fault detector according to claim 1, characterized in that, The signal acquisition module is a test clamp, test probe, or test pen.

10. The fault detector according to claim 1, characterized in that, It is also equipped with a Bluetooth module and / or a Wi-Fi module, which can synchronize the acquired detection data and / or results to the target object, including mobile devices or the cloud.

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