Battery pack water inlet detection device with self-checking function and detection method thereof

Abstract

The invention provides a battery pack water inflow detection device with a self-checking function and a detection method thereof. The device mainly comprises a touch film, a touch IC (Integrated Circuit), a main control IC and a communication circuit. Based on the capacitive touch principle, the touch film is distributed according to all positions of the battery pack structure and is connected to the BMS board, and the touch sensitivity of the touch film can be changed after water is attached to the touch film. The touch IC is used for collecting capacitance value variation of the touch film, and the master control IC periodically queries a touch sensitivity value detected by the touch IC and compares the touch sensitivity value with a factory reference value to judge whether water enters the battery pack or not. According to the invention, low-cost and multi-sampling-point battery pack water inlet detection is realized, and the problems of high cost, great temperature influence and the like of a humidity sensor in the prior art are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, specifically to the waterproof detection technology of battery packs, and particularly to a battery pack water ingress detection device with a self-checking function and its detection method. Background Art

[0002] With the popularization of new energy vehicles, the sealing detection of battery packs has become a core safety requirement. Existing technologies generally use humidity and temperature sensors to indirectly detect water seepage, infer the water ingress risk by monitoring the humidity change in the battery compartment, or, for example, rely on resistance voltage division to detect capacitance changes as in CN111751743B for detection. Such solutions have the following limitations: 1. Environmental dependence: Humidity sensors are vulnerable to interference from condensed water, environmental temperature and humidity fluctuations, with a false alarm rate as high as 15% - 20%; the resistance method is also vulnerable to temperature interference and has a relatively high false alarm rate; 2. Response delay: It is necessary to wait for the humidity change caused by liquid evaporation, and direct contact detection cannot be achieved. The typical response time exceeds 30 seconds; 3. Inadequate coverage: Single-point sensors are difficult to detect local leaks in the complex cavity structure of the battery pack. Deploying multiple sensors will cause a sharp increase in cost (the cost of a single Honeywell HIH-4000 sensor exceeds $6); the resistance method is only applicable to the overall detection of the battery pack; 4. Lack of hardware linkage: Existing solutions only achieve data reporting and lack a real-time hardware linkage cut-off mechanism with the battery management system.

[0003] Therefore, there is an urgent need for a battery pack water ingress detection device with a self-checking function and its detection method to solve the fatal defects of the existing battery pack water ingress detection technology relying on indirect monitoring by humidity and temperature sensors, such as high detection latency, high cost for multi-point deployment, inability to distinguish between condensed water and real leaks, and lack of a hardware-level safety blocking mechanism. Summary of the Invention

[0004] Embodiments of the present invention provide a battery pack water ingress detection device with a self-checking function and its detection method, aiming at the problems existing in current technologies, such as high cost, susceptibility to temperature interference resulting in insufficient accuracy, and untimely response to trace water intrusion.

[0005] The core technology of the present invention mainly realizes high-precision and anti-interference detection of the waterproof state of the battery pack through multi-channel sensitivity detection of a capacitive touch film, combined with the dynamic comparison of the initial sensitivity value and the real-time sensitivity value by the main control IC.

[0006] In a first aspect, the present invention provides a battery pack water ingress detection device with a self-checking function, including the BMS of the battery pack, and further including: A capacitive touch film array, provided with a plurality of detection points, for detecting capacitance changes in corresponding areas of the battery pack; A touch IC is provided on the BMS and electrically connected to the capacitive touch film array for collecting the sensitivity values of each detection point. A main control IC is communicatively connected to the touch IC for obtaining the sensitivity values collected by the touch IC, comparing the real-time sensitivity values with the initial sensitivity values, and generating a reporting signal when the comparison result exceeds a preset threshold; the preset threshold is obtained by multiplying the difference between the sensitivity values of the battery pack without water ingress and with water ingress by a preset coefficient. A communication module is connected to the main control IC for transmitting the reporting signal to the vehicle system and / or the cloud platform.

[0007] Further, the capacitive touch film array is a film made of ITO-PET material.

[0008] Further, the touch IC is provided with a plurality of signal acquisition channels, and each signal acquisition channel is connected to a detection point of the capacitive touch film array in a one-to-one correspondence.

[0009] Further, the main control IC includes: A reference value storage unit for storing the reference sensitivity values of each channel collected by the touch IC in a dry state. A threshold calculation unit for obtaining the sensitivity values collected by the touch IC, comparing the real-time sensitivity values with the initial sensitivity values, and comparing the comparison result with a preset threshold. A safety decision unit for generating a disconnection instruction when it is detected that the real-time sensitivity value of at least one channel exceeds the preset threshold.

[0010] Further, the preset coefficient is 0.5 - 0.9.

[0011] Further, the main control IC reads the real-time sensitivity values of each channel of the touch IC in a periodic manner, and the cycle duration is adaptively set according to the operating conditions of the battery pack.

[0012] Further, the detection points of the capacitive touch film array are arranged in the water-proof weak areas of the battery pack.

[0013] Further, the initial sensitivity value is the sensitivity value detected when the battery pack leaves the factory without water ingress.

[0014] Further, the capacitive touch film array is equipped with a flexible flat cable, and pins are provided at the end of the cable and fixed to the corresponding pins of the touch IC on the BMS by welding to achieve physical conduction.

[0015] In a second aspect, the present invention provides a detection method for a battery pack water ingress detection device with a self-checking function, including the following steps: In the production and assembly stage of the battery pack, the main control IC obtains the sensitivity values of each channel of the touch IC as initial values. Read the current sensitivity values of each channel of the touch IC in real time through the main control IC; Compare the difference between the current sensitivity value and the corresponding initial value with a preset threshold; If the difference is greater than the preset threshold, report it to the vehicle system or the cloud platform through the communication module.

[0016] The main contributions and innovations of the present invention are as follows: 1. Cost advantage: In the prior art, a humidity sensor is added to the BMS board to detect battery pack water ingress, and the cost of the humidity sensor is relatively high. The present invention uses components such as a capacitive touch film and a touch IC, which are widely supplied in the market and have low costs, achieving multi-sampling point detection at a low cost and effectively reducing the cost investment for battery pack water ingress detection.

[0017] 2. Higher detection accuracy: In the prior art, the resistance value of the humidity-sensitive resistor is affected by the temperature change inside the battery pack, resulting in difficult control methods and difficult to ensure detection accuracy. The present invention utilizes the capacitive touch principle to judge the water ingress situation by identifying the change in the touch sensitivity of the touch film before and after water ingress through the touch IC. The change in touch sensitivity mainly depends on whether the touch film is attached with water and is less interfered by other factors such as temperature, and can more accurately judge whether the corresponding position of the battery pack is water ingress, improving the detection accuracy and reliability.

[0018] 3. Multi-point detection and precise positioning: The present invention can place multiple touch films at different positions inside the battery pack according to the battery pack structure as required to achieve multi-sampling point detection. Once an abnormal touch sensitivity value of a certain membrane channel is detected, the corresponding water ingress position inside the battery pack can be accurately located, facilitating subsequent targeted maintenance and treatment. In the prior art, using a humidity sensor may only detect the overall humidity change inside the battery pack and it is difficult to accurately determine the specific water ingress position.

[0019] 4. Quick response and safety guarantee: After the present invention detects battery pack water ingress, the main control IC can quickly upload the water ingress fault information to the vehicle controller and the cloud (if any), and promptly disconnect the relay or the main MOS transistor, disconnect the battery input and prohibit charging, and quickly take measures to ensure battery safety, avoiding safety problems caused by continued use of the battery with water ingress. In contrast, in the prior art, after detecting the water ingress problem, due to insufficient detection accuracy or slow response speed, it may not be able to effectively guarantee the safety of the battery and equipment in a timely manner.

[0020] Details of one or more embodiments of the present invention are set forth in the following drawings and description to make other features, objects, and advantages of the present invention more concise and understandable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a circuit structure diagram of a battery pack water ingress detection device with a self-check function according to an embodiment of the present invention; Figure 2 is a physical diagram of a capacitive touch film array according to an embodiment of the present invention; Figure 3 is a flowchart of a battery pack water ingress detection method with a self-check function according to an embodiment of the present invention. Detailed implementation manners

[0022] Here, the exemplary embodiments will be described in detail, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with one or more embodiments of this specification. On the contrary, they are merely examples of devices and methods consistent with some aspects of one or more embodiments of this specification as detailed in the appended claims.

[0023] It should be noted that: In other embodiments, the steps of the corresponding methods are not necessarily executed in the order shown and described in this specification. In some other embodiments, the steps included in the method may be more or less than those described in this specification. In addition, a single step described in this specification may be decomposed into multiple steps for description in other embodiments; and multiple steps described in this specification may also be combined into a single step for description in other embodiments.

[0024] The traditional battery pack waterproof detection scheme has defects such as high cost, susceptibility to temperature interference resulting in insufficient accuracy, and untimely response to trace water intrusion.

[0025] Based on this, the present invention solves the problems existing in the prior art based on capacitive touch film multi-channel sensitivity detection.

[0026] Embodiment 1 The present invention aims to propose a battery pack water ingress detection device with a self-check function. Specifically, referring to Figure 1 and Figure 2 , the device includes: (1) Capacitive touch film (capacitive touch film array) Material: Made of PET substrate coated with indium tin oxide (ITO), such as a thickness of 0.1 mm to 0.3 mm, having flexibility, waterproofness, and electrical conductivity.

[0027] Structure: AsFigure 2 As shown, multiple detection points (such as TK1 - TK5, for inductive detection 1 - inductive detection n in Figure 1 testing) are etched on the thin film, and the area of each detection point is 1 - 3 cm 2 . Signal transmission lines are formed by printing silver paste, and the ends are connected to the connector CN1. The touch film is equipped with a flexible flat cable (FPC), and pins (such as gold fingers) are set at the end of the cable, which are fixedly connected to the corresponding pins of the touch IC on the BMS circuit board by soldering to achieve physical conduction, or a board - to - board vertical plug - in structure is adopted. Processes such as reflow soldering can be used to ensure the firm connection between the cable pins and the touch IC pads and avoid false soldering. Preferably, a shielding layer (such as copper - clad shielding) can also be added to the connection lines to prevent electromagnetic interference; and the connection part is encapsulated with potting glue to enhance the waterproof and dust - proof performance and ensure long - term stable connection.

[0028] Dot - distribution rule: According to the battery pack structure, detection points are arranged at weak positions such as the shell seams, wire harness penetration holes, and areas where waterproof glue is prone to failure, ensuring that the water intrusion paths cover all detection points.

[0029] For example, the dot - distribution of the touch membrane can be carried out according to the following steps: 1. Battery pack structure analysis and weak - point location Disassemble the battery pack, analyze the shell structure, seal positions, interfaces (such as charging interfaces, communication interfaces), etc., and mark the waterproof weak areas (such as seams, wire - passing holes, and places where sealant is prone to failure). These areas are potential paths for water intrusion and are the key areas to focus on for dot - distribution.

[0030] 2. In - water - intrusion simulation verification (simulation or experiment) Simulation analysis: Use fluid mechanics simulation software (such as ANSYS Fluent) to simulate scenarios such as rain impact and wading, observe the penetration trajectory of water flow inside the battery pack, and locate the internal positions where water finally contacts.

[0031] Physical experiment: Conduct spray tests and immersion tests on the battery pack, inject liquid into the pack, mark the inner wall or component surface actually contacted after water intrusion, and determine the key areas where water needs to contact the membrane.

[0032] 3. Dot - distribution design and quantity determination Dot - distribution principle: Inside the water - contact area verified by simulation, detection points are distributed according to the battery pack size and waterproof risk level. For example, for a linear water - intrusion path (such as a long - strip seam), multiple detection points are evenly arranged along the path; for an independent chamber, at least 1 detection point is arranged in each chamber.

[0033] Quantity determination: Considering both detection accuracy and cost, if 3 high - risk water - intrusion areas are found in a certain battery pack through simulation, then 3 groups of detection points are arranged correspondingly, with each group containing 1 or more detection points, and finally the total number of dot - distributions n is determined.

[0034] 4. Diaphragm customization and production Design a capacitive touch film according to the dot placement positions, quantities, and internal structures of the battery packs: Appearance customization: Use flexible ITO-PET material to process the film shape (such as long strip shape, special shape) according to the inner wall contour of the battery pack to ensure a snug fit for installation.

[0035] Integration of detection points: Make detection points (such as TK1-TK5) at the corresponding water contact positions on the film, plan the internal circuit traces, match the signal acquisition channels of the touch IC, and finally complete the encapsulation to ensure the waterproofness of the film and the stability of signal detection.

[0036] (2) Touch IC circuit Model selection: Select a capacitive touch IC with an I 2 C interface, which supports 15-channel signal acquisition, and each channel corresponds to a touch film detection point.

[0037] Circuit design: Connect the VDD pin of the touch IC to a 3.3V power supply, connect the SDA / SCL pins to the I 2 C bus of the main control IC, and connect the pins of each detection channel to the touch film detection points through FPC cables respectively (refer to the Figure 1 electrical connection diagram).

[0038] (3) Integration of the main control IC and BMS Main control chip: For example, use the STM32F103RET6 microcontroller of STMicroelectronics to periodically read the data of the touch IC through the I 2 C bus, and internally store the initial sensitivity values in the Flash.

[0039] Safety control: Connect the GPIO pin of the main control IC to the driving circuit of the main relay of the battery pack. When water ingress is detected, output a low-level signal to disconnect the relay.

[0040] Embodiment 2 Based on the same concept, the present invention also proposes a detection method for a battery pack water ingress detection device with a self-check function, including: Step 1. Initialization of the reference value (production stage) When the battery pack is assembled and there is no water ingress, the main control IC reads the original sensitivity values (A1-A5) of each channel of the touch IC through the I 2 C bus and stores them in the EEPROM of the BMS.

[0041] Step 2. Real-time detection logic (usage stage) Data acquisition: The main control IC reads the data of the touch IC through the I 2The C bus queries the current sensitivity values (B1~B5) of each channel of the touch IC.

[0042] Threshold calculation: The preset threshold C = (B_wet - A_dry) × 0.7 (where B_wet is the sensitivity value after simulating water ingress, and A_dry is the reference value in the dry state).

[0043] Comparison and determination: If Bn - An > C for any channel, mark the area corresponding to that channel as the water ingress state.

[0044] In this embodiment, for example, in the reference value establishment stage: a) After completing the battery pack assembly, collect the initial values A1 - A5 of each channel through the touch IC in a dry environment (such as the typical value range is 800 - 1200); b) Inject 0.8 ml of deionized water into the TK3 contact and record the maximum sensitivity value B0 (typical value ≥ 2500); c) Calculate the dynamic threshold according to the formula C3 = 0.75 × (B0 - A3) (example: if A3 = 1000 and B0 = 2500, then C3 = 1125).

[0045] Step 3. Fault response mechanism Hierarchical alarm: When a single channel triggers an alarm, the main control IC sends a fault code P0A94 (battery pack water ingress) to the whole vehicle through the CAN bus; if the same channel is detected to be abnormal continuously for 3 times, trigger the emergency disconnection relay.

[0046] Data upload: Push the fault information to the cloud monitoring platform through a 4G module (such as Quectel BC95) or a 5G module, including the water ingress location, timestamp, and sensitivity change curve.

[0047] Embodiment 3 Based on the same concept, the present invention adds failure diagnosis means, specifically as follows: 1. Thin film failure detection: When Δn < 0.2An for 5 consecutive cycles in a certain channel (such as Δ3 < 200 when A3 = 1000); Trigger the pin enable diagnosis mode of the main control IC as in Figure 1 and send a fault code 0xE1 through the pin; 2. Communication redundancy switching: The main communication link and the standby link run in parallel; When the main link signal is lost for more than 50 ms, automatically switch to the standby link to maintain detection.

[0048] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementation manners, and will not be elaborated here.

[0049] In general, various embodiments may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects of the present invention may be implemented in hardware, while other aspects may be implemented by firmware or software executed by a controller, microprocessor, or other computing device, but the present invention is not limited thereto. Although various aspects of the present invention may be shown and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, by way of non-limiting example, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general hardware or a controller or other computing device, or some combination thereof.

[0050] Embodiments of the present invention may be implemented by computer software executable by a data processor of a mobile device, such as in a processor entity, or by hardware, or by a combination of software and hardware. A computer software or program (also referred to as a program product), including software routines, applets, and / or macros, may be stored in any device-readable data storage medium, and they include program instructions for performing specific tasks. The computer program product may include one or more computer-executable components configured to perform the embodiments when the program runs. The one or more computer-executable components may be at least one software code or a part thereof. Additionally, in this regard, it should be noted that any block in the logical flow in the figures may represent a program step, or an interconnected logical circuit, block, and function, or a combination of a program step and a logical circuit, block, and function. The software may be stored on physical media such as memory chips or storage blocks implemented within the processor, magnetic media such as hard disks or floppy disks, and optical media such as, for example, DVDs and their data variants, CDs. The physical media is a non-transitory medium.

[0051] Those skilled in the art should understand that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0052] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A battery pack water ingress detection device with a self-checking function, comprising a BMS of a battery pack, characterized in that: Also includes: Capacitive touch film array, with multiple detection points, used to detect the capacitance change of the corresponding area of ​​the battery pack; A touch IC, which is disposed on the BMS and is electrically connected to the capacitive touch film array and is used to collect the sensitivity value of each detection point; A main control IC is connected to the touch IC for obtaining the sensitivity value collected by the touch IC, comparing the real-time sensitivity value with the initial sensitivity value, and generating a reporting signal when the comparison result exceeds a preset threshold; The preset threshold is obtained by multiplying the difference between the sensitivity values ​​of the battery pack not being flooded and the battery pack being flooded by a preset coefficient; A communication module, the communication module is connected to the main control IC and is used to transmit the reporting signal to the vehicle system and / or the cloud platform.

2. A battery pack water ingress detection device with a self-checking function as claimed in claim 1, characterized in that: The capacitive touch film array is a film made of ITO-PET material.

3. A battery pack water ingress detection device with a self-checking function as claimed in claim 1, characterized in that: The touch IC is provided with a plurality of signal acquisition channels, and each signal acquisition channel is connected to a detection point of the capacitive touch film array in a one-to-one correspondence.

4. A battery pack water ingress detection device with a self-checking function as claimed in claim 1, characterized in that: The main control IC includes: A reference value storage unit, storing the reference sensitivity value of each channel collected by the touch IC in a dry state; The threshold calculation unit obtains the sensitivity value collected by the touch IC, compares the real-time sensitivity value with the initial sensitivity value, and compares the comparison result with the preset threshold value; The safety decision unit generates a disconnection instruction when it is detected that the real-time sensitivity value of at least one channel exceeds a preset threshold.

5. A battery pack water ingress detection device with a self-checking function as claimed in claim 1, characterized in that: The preset coefficient is 0.5-0.

9.

6. A battery pack water ingress detection device with a self-checking function as claimed in claim 1, characterized in that: The main control IC reads the real-time sensitivity values ​​of each channel of the touch IC in real time at a frequency of periodic reading, and the cycle duration is set according to the adaptability of the battery pack usage conditions.

7. A battery pack water ingress detection device with a self-checking function as claimed in claim 1, characterized in that: The detection points of the capacitive touch film array are arranged in the waterproof weak area of ​​the battery pack.

8. A battery pack water ingress detection device with a self-checking function as claimed in claim 1, characterized in that: The initial sensitivity value is a sensitivity value obtained when the battery pack is detected without water ingress when it leaves the factory.

9. A battery pack water ingress detection device with a self-checking function as claimed in any one of claims 1 to 8, characterized in that: The capacitive touch film array is equipped with a flexible flat cable, and pins are arranged at the ends of the cable, which are fixed to the corresponding pins of the touch IC on the BMS by welding to achieve physical conduction.

10. The detection method of the battery pack water ingress detection device with self-checking function according to any one of claims 1 to 9, characterized in that: The following steps are involved: During the battery pack production and assembly stage, the sensitivity value of each channel of the touch IC is obtained through the main control IC as the initial value; The current sensitivity value of each channel of the touch IC is read in real time through the main control IC; Compare the difference between the current sensitivity value and the corresponding initial value with a preset threshold; If the difference is greater than the preset threshold, it will be reported to the vehicle system or cloud platform through the communication module.

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