A large cell module aluminum bar welding heat resistance monitoring and life warning method

Abstract

This invention discloses a method for monitoring the welding thermal resistance and providing lifespan early warning for aluminum busbars in large battery cell modules. The method involves acquiring a first temperature of the aluminum busbar, a second temperature at the bottom center of the thermally resistive battery cell, and a third temperature on the surface of a temperature-sensitive water-cooled plate using a temperature measurement module, and determining the temperature difference. When the early warning output module receives the temperature difference data and determines it to be within a first preset value range, it acquires the charging and discharging data and temperature difference fluctuation deviation of the thermally resistive battery cell from the BMS main control module. The BMS main control module transmits the number of charging cycles to the temperature measurement module to execute a preset patrol temperature measurement strategy. If the temperature difference fluctuation deviation exceeds a second preset value, it acquires the charging and discharging power received by the early warning output module, calculates the thermal resistance value of the thermally resistive battery cell, and sends a thermal resistance anomaly message to the BMS main control module if the thermal resistance value exceeds the thermal resistance curve deviation fluctuation range of the thermally resistive battery cell, and executes a target charging and discharging command. The total thermal resistance of the battery cell is broken down into the body, interface, and welding, extracting the core monitoring indicators of welding thermal resistance and accurately distinguishing the causes of failure.

Description

Technical Field

[0001] This invention belongs to the field of energy storage thermal management technology, and in particular relates to a method for monitoring the thermal resistance of aluminum busbar welding in large battery cell modules and providing early warning of their lifespan. Background Technology

[0002] In energy storage systems, liquid-cooled battery modules have become the mainstream technology due to their efficient thermal management performance, especially the large-cell 587Ah and 588Ah models. The heat generation of a single 587Ah cell is more than double that of the previous 280Ah and 314Ah cells, posing a significant challenge to the thermal resistance stability of the aluminum busbar welding process in battery modules. The welding quality of the cell terminals and the aluminum busbar directly determines the reliability and lifespan of the battery module's electrical connection. Problems such as incomplete welding, fatigue cracks, increased contact resistance, and pores in the thermally conductive adhesive between the cell and the water-cooling plate can lead to abnormal local temperature rises, exacerbated thermal unevenness, and consequently, inconsistent cell degradation, thermal runaway risks, and even battery module failure.

[0003] Currently, existing technologies for inspecting the welding quality of battery modules include in-weld detection, but these are not correlated with pull-out force and carry the risk of incomplete welds. Most inspections involve offline manual disassembly of battery modules (such as X-rays and tensile tests), which is insufficient for intelligent online real-time monitoring in energy storage scenarios. Some online monitoring solutions rely solely on single-point temperature or DC internal resistance detection to identify anomalies, resulting in low accuracy, high false alarm rates, and an inability to precisely pinpoint welding degradation issues. A few solutions using cell temperature measurement only monitor the temperature at a single location within the cell, failing to consider the heat transfer characteristics under liquid cooling conditions. This makes it impossible to differentiate between temperature rises caused by cell-level heating, poor liquid-cooling interface contact, and aluminum busbar welding degradation. Furthermore, existing technologies do not use thermal resistance as a core characteristic for quantitative analysis and lifespan warning of welding degradation, making it difficult to meet the practical needs of long-term online health management of liquid-cooled battery modules. Therefore, there is an urgent need to provide a method for monitoring the thermal resistance and providing lifespan warnings of aluminum busbar welding in large-cell modules to address the aforementioned technical problems. Summary of the Invention

[0004] In view of this, the present invention provides a method for monitoring the welding thermal resistance and lifespan warning of aluminum busbars in large battery modules. The total thermal resistance of the battery cells in the battery module can be divided into three parts: the body, the interface, and the welding. The welding thermal resistance is extracted as the core monitoring indicator to accurately distinguish different fault causes, so as to achieve dedicated monitoring of welding deterioration. It is suitable for all energy storage applications and greatly reduces the detection cost. The specific technical solution is as follows.

[0005] This invention provides a method for monitoring the thermal resistance and providing lifespan warning of aluminum busbar welding in large-cell modules, applied to a large-cell module energy storage system. The large-cell module energy storage system includes a cell module and end plates disposed on both sides of the cell module. The cell module includes a cell unit, a temperature measurement module, a BMS main control module, and a warning output module. The cell unit includes multiple thermal resistance cells, multiple aluminum busbars, and a temperature-sensing water-cooled plate. The multiple aluminum busbars are disposed on the multiple thermal resistance cells and connected to the positive and negative terminals of adjacent thermal resistance cells. The temperature-sensing water-cooled plate is located at the bottom of the multiple thermal resistance cells. The thermal resistance monitoring and lifespan warning method includes: The temperature measurement module collects the first temperature of each aluminum busbar, the second temperature of the bottom center of each thermal resistance cell, and the third temperature of the surface of the temperature-sensing water-cooled plate corresponding to each thermal resistance cell. The temperature difference value of each thermal resistance cell is determined based on the first temperature, the second temperature, and the third temperature. The temperature difference data includes the first temperature, the second temperature, the third temperature, and the temperature difference value of all collected thermal resistance cells. When the early warning output module receives the temperature difference data uploaded by the temperature measurement module and determines that the temperature difference data is within the first preset value range, it acquires the charging and discharging data of each thermal resistance cell collected by the BMS main control module and the temperature difference fluctuation deviation corresponding to the temperature difference data. The charging and discharging data includes at least one of the following for each thermal resistance cell: voltage, charging and discharging power, number of charging and discharging cycles, charging and discharging energy, or charging and discharging capacity. The BMS main control module is controlled to upload the number of charging cycles to the temperature measurement module to execute a preset patrol temperature measurement strategy, and to determine whether the temperature difference fluctuation deviation exceeds a second preset value. If so, obtain the charging and discharging power uploaded by the BMS main control module to the early warning output module, and calculate the thermal resistance value of the thermal resistance cell based on the charging and discharging power; When the thermal resistance value exceeds the thermal resistance curve deviation reference fluctuation range of the thermal resistance cell, the warning output module is controlled to send thermal resistance abnormality information corresponding to the thermal resistance value to the BMS main control module, and the BMS main control module executes the target charge and discharge command corresponding to the thermal resistance abnormality information.

[0006] As a preferred embodiment of the above technical solution, the temperature measurement module includes a first temperature sensing probe, a second temperature sensing probe, and a thermistor. The first temperature sensing probe is disposed on the plurality of aluminum busbars, the second temperature sensing probe is disposed at the bottom of each of the thermal resistance cells, and the thermistor is located at the center of the bottom of each of the thermal resistance cells and on the surface of the temperature-sensing water-cooled plate. The first temperature sensor is used to collect the first temperature of the aluminum busbar, the second temperature sensor is used to collect the second temperature of the bottom of the plurality of thermal resistance cells, and the thermistor is used to monitor the third temperature of the surface of the temperature-sensitive water-cooled plate at the corresponding position of each thermal resistance cell.

[0007] As a preferred embodiment of the above technical solution, the cell number of the plurality of thermal resistance cells is preset to be a. Then, the first temperature measured by the first temperature sensing probe corresponding to the aluminum busbar on the upper surface of the a-th thermal resistance cell is Tu,a, the second temperature measured by the second temperature sensing probe at the bottom of the a-th thermal resistance cell is Td,a, and the third temperature measured by the thermistor on the temperature-sensing water-cooling plate at the position corresponding to the a-th thermal resistance cell is Tc,a, where a = 1, 2, 3... 104. The temperature measurement module determines the first temperature difference between the bottom of the a-th thermal resistance cell and the aluminum busbar as △T1(a)=Tu,a-Td,a based on the first temperature and the second temperature, and determines the second temperature difference between the bottom of the a-th thermal resistance cell and the surface of the temperature-sensing water-cooled plate as △T2(a)=Td,a-Tc,a based on the second temperature and the third temperature. The temperature measurement module uploads the temperature difference data to the BMS main control module. When the BMS main control module determines that the temperature difference fluctuation deviation is within the second preset value range, the BMS main control module controls the temperature measurement module to execute the preset patrol temperature measurement strategy.

[0008] As a preferred embodiment of the above technical solution, when the temperature measurement module receives a temperature difference fluctuation deviation uploaded by the BMS main control module that exceeds the second preset value range, the temperature measurement module suspends the execution of the preset patrol temperature measurement strategy. The temperature measurement module is controlled to execute the dense patrol temperature collection strategy in the preset patrol temperature measurement strategy. The BMS main control module uploads the charging and discharging power to the early warning output module. The predicted patrol temperature measurement strategy includes setting the patrol temperature measurement interval time according to the number of charge and discharge cycles of each thermal resistance cell. The early warning output module calculates the thermal resistance value of the thermal resistance cell based on the charging and discharging power. The BMS main control module receives the thermal resistance abnormality information corresponding to the thermal resistance value and executes reduced power charging or pauses charging and discharging. The target charging and discharging command includes reduced power charging and pauses charging and discharging.

[0009] As a preferred embodiment of the above technical solution, the early warning output module calculates the thermal resistance value of the thermal resistance cell based on the charging and discharging power, including: The total thermal resistance of the battery cell corresponding to the thermal resistance value is broken down to obtain the thermal resistance breakdown result. Based on the thermal resistance breakdown results and the charge / discharge power, multiple thermal resistance models of the battery cell are constructed. Based on the multiple thermal resistance models and the charge / discharge data, thermal resistance anomaly information of multiple thermal resistance cells is determined. The pre-set early warning output module breaks down the total thermal resistance of the battery cell into the thermal resistance of the battery cell body Rc, the thermal resistance from the bottom of the battery cell to the aluminum busbar Rb, the interface thermal resistance from the surface of the temperature-sensing water-cooled plate to the bottom of the battery cell Rs, and the welding thermal resistance between the battery cell electrode and the aluminum busbar Rj. Multiple thermal resistance models are included: the separation model of the total thermal resistance component is Rz=(Rc+Rj)+Rs, the thermal resistance model from the bottom of the cell to the aluminum busbar is Rb=Rc+Rj=△T1(a) / P, the interface thermal resistance model from the surface of the temperature-sensing water-cooled plate to the bottom of the cell is Rs=△T2(a) / P, and the welding thermal resistance model between the cell electrode and the aluminum busbar is Rj=Rb-Rc.

[0010] As a preferred embodiment of the above technical solution, the process for handling deviations in the determination of the thermal resistance Rc of the battery cell body includes: Multiple sets of thermal resistance cells were subjected to full-life-cycle cyclic charge-discharge thermal resistance testing at the charge-discharge power and the ambient temperature corresponding to the charge-discharge power. Calculate the third temperature difference between the bottom and top of the thermal resistance cell, and calculate the cell body thermal resistance values ​​of multiple sets of thermal resistance cells based on the third temperature difference value, wherein all multiple sets of cell body thermal resistance values ​​conform to a normal distribution. Obtain a normal distribution curve as the curve of change of the thermal resistance value of the battery cell body with the number of charge and discharge cycles throughout the entire life cycle of the battery cell body, and import the standard test thermal resistance curve of the battery cell body throughout the entire life cycle into the warning output module according to the curve of change. The standard test cell body thermal resistance curve is used as the thermal resistance curve deviation benchmark Re0 from the bottom of the cell to the aluminum busbar. The area where the measured thermal resistance value from the bottom of the cell to the aluminum busbar exceeds the upper deviation limit Rcs or the lower deviation limit Rcx of the cell body thermal resistance curve is defined as the thermal resistance alarm area from the bottom of the cell to the aluminum busbar. The area between the upper deviation limit Rcs and the lower deviation limit Rcx of the cell body thermal resistance curve is defined as the normal thermal resistance area from the bottom of the cell to the aluminum busbar. The fluctuation range of the thermal resistance curve deviation benchmark is set according to the thermal resistance curve deviation benchmark Re0, the upper deviation limit Rcs, and the lower deviation limit Rcx area.

[0011] As a preferred embodiment of the above technical solution, the process for handling deviations in the thermal resistance judgment of the interface thermal resistance Rs from the surface of the temperature-sensing water-cooled plate to the bottom of the battery cell includes: A test environment was set up for the contact between the battery cell and the water-cooled plate through thermally conductive adhesive, and a full life cycle charge-discharge thermal resistance test was carried out using multiple sets of thermally resistive battery cells. The thermally conductive adhesive was placed between the thermally resistive battery cell and the temperature-sensitive water-cooled plate. Obtain the fourth temperature difference between the surface of the water-cooled plate and the bottom of the thermally resistive cell, and calculate the interface thermal resistance Rs based on the fourth temperature difference to generate the Rs thermal resistance curve for the entire life cycle of the cell. Based on the Rs thermal resistance curve, the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell under the full life cycle standard test of the thermal resistance cell is imported into the early warning output module, and the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell is used as the deviation benchmark Rs0 of the thermal resistance curve from the surface of the temperature-sensing water-cooled plate to the bottom of the cell. The area where the measured thermal resistance of the battery cell exceeds the upper deviation limit Rss of the thermal resistance curve from the surface of the water-cooled plate to the bottom of the battery cell or the lower deviation limit Rsx of the thermal resistance curve from the surface of the water-cooled plate to the bottom of the battery cell is identified as the thermal resistance alarm area from the surface of the water-cooled plate to the bottom of the battery cell. The area within the upper deviation limit Rss of the thermal resistance curve of the battery cell body and the lower deviation limit Rsx of the thermal resistance curve of the battery cell body is identified as the normal thermal resistance area from the surface of the water-cooled plate to the bottom of the battery cell.

[0012] As a preferred embodiment of the above technical solution, the early warning output module generates respective thermal resistance curves based on the thermal resistance Rb from the bottom of the battery cell to the aluminum busbar and the thermal resistance Rs from the surface of the water-cooled plate to the bottom of the battery cell during the cyclic charging and discharging process, and compares the deviations with the imported standard test thermal resistance curves, including: When Rb ≤ Rcx or Rs ≤ Rsx and the charging / discharging power P remains constant, the warning output module issues an alarm, indicating a problem with the temperature acquisition of cell number a. When Rcx < Rb < Rcs or Rsx < Rs < Rss and the charging / discharging power P remains unchanged, the warning output module does not issue an alarm. When Rb≥Rcs and the temperature is within the first preset range, the warning output module issues an alarm and provides a warning about the thermal resistance problem of the aluminum busbar welding of cell number a. When Rb≥Rcs and the temperature exceeds the first preset value range, the warning output module issues an alarm and prompts a warning about the thermal resistance of the cell body and the cell cycle life of cell number a. When Rs≥Rss, the warning output module issues an alarm and indicates that the water cooling plate and the thermal conductive adhesive at the bottom of the cell number a are loose or have gaps.

[0013] As a preferred embodiment of the above technical solution, the large cell module energy storage system further includes a housing, a steel strip, and a temperature sensing socket. The housing is disposed on the upper surface of the cell module and covers the end plate. The two ends of the steel strip are respectively connected to the two end plates. The steel strip is attached to the cell unit. The temperature sensing socket is disposed at the bottom of the thermal resistance cell. The second temperature sensing probe is connected to the temperature measurement module through the temperature sensing socket.

[0014] As a preferred embodiment of the above technical solution, the preset patrol temperature measurement strategy includes: If the preset number of charge / discharge cycles for the thermal resistance battery cell is N, and the patrol temperature measurement interval is T, then: When 0 < N ≤ 500 times, T = 60 min, the temperature measuring module patrols and collects temperature once every 60 minutes; When 500 < N ≤ 1000 times, T = 40 min, the temperature measuring module patrols and collects temperature once every 40 minutes; When 1000 < N ≤ 1500 times, T = 20 min, the temperature measuring module patrols and collects temperature once every 20 minutes; When 1500 < N ≤ 2000 times, T = 10 min, the temperature measuring module patrols and collects temperature once every 10 minutes; When 2000 < N ≤ 2500 times, T = 5 min, the temperature measuring module patrols and collects temperature once every 5 minutes; When 2500 < N ≤ 3000 times, T = 1 min, the temperature measuring module patrols and collects temperature once every 1 min; When 3000 < N ≤ 5000 times, T = 0.5 min, the temperature measuring module patrols and collects temperature once every 30 seconds; When N > 5000 times, T = 0.167 min, the temperature measurement module patrols and collects temperature once every 10 seconds; Among them, patrolling and collecting temperature every 10 seconds is the dense patrol and temperature collection strategy.

[0015] This invention provides a method for monitoring the thermal resistance of aluminum busbar welding in large battery cell modules and for early warning of their lifespan. The method involves setting up a battery cell module and an end plate. The battery cell module includes a cell unit, a temperature measurement module, a BMS main control module, and an early warning output module. The temperature measurement module collects a first temperature of each aluminum busbar, a second temperature at the bottom center of each thermally resistive cell, and a third temperature on the surface of the corresponding temperature-sensitive water-cooled plate. Based on these three temperatures, the temperature difference value for each thermally resistive cell is determined. When the early warning output module receives the temperature difference data uploaded by the temperature measurement module and determines that the temperature difference data is within a first preset value range, it acquires the temperature difference fluctuation deviation corresponding to the charge / discharge data and temperature difference data collected by the BMS main control module for each thermally resistive cell, and controls the BMS accordingly. The main control module uploads the number of charging cycles to the temperature measurement module to execute the preset patrol temperature measurement strategy. It also determines whether the temperature difference fluctuation exceeds the second preset value, obtains the charging and discharging power uploaded by the BMS main control module to the early warning output module, and calculates the thermal resistance value of the thermal resistance cell based on the charging and discharging power. When the thermal resistance value exceeds the baseline fluctuation range of the thermal resistance curve deviation of the thermal resistance cell, it controls the early warning output module to send thermal resistance abnormality information to the BMS main control module. The BMS main control module executes the corresponding target charging and discharging command. It can break down the total thermal resistance of the cells in the battery module into three parts: body, interface, and welding. It extracts the welding thermal resistance as the core monitoring indicator, accurately distinguishes different fault causes, realizes dedicated monitoring of welding degradation, adapts to all energy storage application scenarios, and significantly reduces detection costs. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart of the method for monitoring the welding thermal resistance and lifespan warning of aluminum busbars in large battery cell modules provided by the present invention; Figure 2 This is a schematic diagram of the structure of the large-cell module energy storage system provided by the present invention; Figure 3 This is a top view of the large-cell module energy storage system provided by the present invention; Figure 4 The curve of thermal resistance judgment deviation provided by the present invention.

[0018] The symbols for the main components are explained below: 10-Battery cell module; 20-End board; 21-Temperature measurement module; 22-BMS main control module; 23-Early warning output module; 24-Thermoresistive cell; 25-Aluminum busbar; 26-Temperature-sensing water-cooled plate; 27-First temperature sensor probe; 28-Second temperature sensor probe; 29-Thermistor; 30-Thermoconductive adhesive; 31-Housing; 32-Steel strip; 33-Temperature-sensing female connector. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] It should be noted that when an element is said to be "fixed" to another element, it can be directly on the other element or there may be an intervening element. When an element is said to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. Conversely, when an element is said to be "directly" on another element, there is no intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] See Figure 1 , Figure 2 and Figure 3 This invention provides a method for monitoring the thermal resistance and providing lifespan warning of aluminum busbar welding in a large battery cell module, applied to a large battery cell module energy storage system. The large battery cell module energy storage system includes a battery cell module 10 and end plates 20 disposed on both sides of the battery cell module 10. The battery cell module 10 includes a battery cell unit, a temperature measurement module 21, a BMS main control module 22, and a warning output module 23. The battery cell unit includes multiple thermal resistance cells 24, multiple aluminum busbars 25, and a temperature-sensing water-cooled plate 26. The multiple aluminum busbars 25 are disposed on the multiple thermal resistance cells 24 and connected to the positive and negative terminals of adjacent thermal resistance cells 24. The temperature-sensing water-cooled plate 26 is located at the bottom of the multiple thermal resistance cells 24. The thermal resistance monitoring and lifespan warning method includes: S1: The temperature measuring module 21 collects the first temperature of each aluminum busbar 25, the second temperature of the bottom center of each thermal resistance cell 24, and the third temperature of the surface of the temperature-sensing water-cooled plate 26 corresponding to each thermal resistance cell 24, and determines the temperature difference value of each thermal resistance cell 24 based on the first temperature, the second temperature, and the third temperature. The temperature difference data includes the first temperature, the second temperature, the third temperature, and the temperature difference value of all collected thermal resistance cells 24. S2: When the early warning output module 23 receives the temperature difference data uploaded by the temperature measurement module 21 and determines that the temperature difference data is within the first preset value range, it acquires the charging and discharging data of each thermal resistance cell 24 collected by the BMS main control module 22 and the temperature difference fluctuation deviation corresponding to the temperature difference data. The charging and discharging data includes at least one of the following for each thermal resistance cell 24: voltage, charging and discharging power, number of charging and discharging cycles, charging and discharging energy, or charging and discharging capacity. S3: Control the BMS main control module 22 to upload the number of charging cycles to the temperature measurement module 21 to execute the preset patrol temperature measurement strategy, and determine whether the temperature difference fluctuation deviation exceeds the second preset value; S4: If so, obtain the charging and discharging power uploaded by the BMS main control module 22 to the early warning output module 23, and calculate the thermal resistance value of the thermal resistance cell 24 based on the charging and discharging power; S5: When it is determined that the thermal resistance value exceeds the preset thermal resistance value of the thermal resistance cell 24, the warning output module 23 is controlled to send thermal resistance abnormality information corresponding to the thermal resistance value to the BMS main control module 22, and the BMS main control module 22 executes the target charge and discharge command corresponding to the thermal resistance abnormality information.

[0023] In this embodiment, the temperature measurement module 21 includes a first temperature sensing probe 27, a second temperature sensing probe 28, and a thermistor 29. The first temperature sensing probe 27 is disposed on the plurality of aluminum busbars 25, the second temperature sensing probe 28 is disposed at the bottom of each thermal resistance cell 24, and the thermistor 29 is located at the center of the bottom of each thermal resistance cell 24 and on the surface of the temperature-sensing water-cooled plate 26. The first temperature sensing probe 27 is used to collect the first temperature of the aluminum busbars 25, the second temperature sensing probe 28 is used to collect the second temperature of the bottom of the plurality of thermal resistance cells 24, and the thermistor 29 is used to monitor the third temperature of the surface of the temperature-sensing water-cooled plate 26 at the corresponding position of each thermal resistance cell 24. The large cell module energy storage system also includes a housing 31, a steel strip 32, and a temperature sensing socket 33. The housing 31 is disposed on the upper surface of the cell module 10 and covers the end plate 20. The two ends of the steel strip 32 are respectively connected to the two end plates 20. The steel strip 32 is attached to the cell unit. The temperature sensing socket 33 is disposed at the bottom of the thermal resistance cell 24. The second temperature sensing probe 28 is connected to the temperature measuring module 21 through the temperature sensing socket 33.

[0024] It should be noted that the aluminum busbar 25 is made of high-purity aluminum with considerable hardness and deformation resistance. Its surface is smooth and has two positioning holes (not shown in the figure). The aluminum busbar 25 connects the positive electrode of one (thermally resistive) battery cell to the negative electrode of an adjacent cell using laser welding, fusing the aluminum busbar and the positive and negative electrodes of the battery cell together to ensure minimal weld resistance. Voltage and temperature sensing probes (first temperature sensor 27) are mounted on the surface of the aluminum busbar 25, and all collected data is transmitted to the BMS main control module 22 for storage. The end plate 20 is made of alloy steel with a pressure-resistant insulating coating. The high-strength end plate has dimensions consistent with the battery (cell unit). The end plate 20 has 32mm thick steel strip grooves on its top and bottom. The end plate 20 has pre-drilled through holes in the vertical direction for bolts to pass through and tighten into threaded holes on the corrugated base plate, thus securing the battery cell. The steel strip 32 is made of high-strength and high-toughness polymer composite material with an insulating surface, and has fire-resistant and high-temperature resistant properties. The steel strip 32 is used to press and fix the tail plate, high-strength end plate, expansion force communication sensor and battery together. The strength of the steel strip 32 is greater than the limit expansion force of the battery cell.

[0025] The main difference between the thermal resistance cell 24 and ordinary cells lies in the presence of a temperature sensor (second temperature sensor 28) at the bottom of the cell. This sensor can detect the temperature at the bottom of the cell in real time and transmit the temperature value to the temperature measurement module 21 via the temperature-sensing female socket 33 and the temperature-sensing male plug (not shown). Combined with the temperature value from the temperature sensor (first temperature sensor 27) on the aluminum busbar 25, the total thermal resistance of the cell body, the terminal, and the aluminum busbar 25 is calculated. The temperature-sensing water-cooled plate 26 has internal coolant channels. Low-temperature coolant enters from the inlet and flows out from the outlet, carrying away heat from the cell during this process, achieving indirect liquid cooling through heat dissipation from the bottom of the cell. The temperature-sensitive water-cooled plate 26 is made of aluminum alloy with a high thermal conductivity. Tiny grooves are provided on the surface in contact with the bottom of the battery cell to accommodate surface-mount thermistors 29. One thermistor 29 is placed at the center of the bottom of each battery cell to monitor the surface temperature (interface temperature) of the temperature-sensitive water-cooled plate 26 at the corresponding location of the cell. This temperature difference is then compared with the temperature-sensing probe (second temperature-sensing probe 28) at the bottom of the thermally resistive battery cell 29 to calculate the change in thermal resistance between the battery cell and the thermally conductive adhesive 30. An extremely thin insulating coating is sprayed onto the surface of the temperature-sensitive water-cooled plate 26; its thickness does not affect thermal conductivity and it maintains good adhesion to the thermally conductive adhesive 30. The temperature measurement module 21 can be installed inside the battery module or externally. The temperature measurement module 21 has built-in AI learning and AI algorithms. The temperature measurement module 21 is mainly responsible for the temperature values ​​of the bottom of the thermal resistance cell 24, the surface temperature of the aluminum busbar 25, and the temperature values ​​on the temperature-sensing water-cooled plate 26. It stores the collected temperature values ​​and calculates the temperature difference, the temperature difference from the aluminum busbar 25 to the bottom of the thermal resistance cell (first temperature difference value), and the temperature difference from the bottom of the thermal resistance cell 24 to the surface of the temperature-sensing water-cooled plate 26 (second temperature difference value).

[0026] The BMS main control module 22 is responsible for collecting the cell voltage, calculating power, counting charge / discharge cycles, calculating charge / discharge energy, and calculating charge / discharge capacity. It then uploads the charge / discharge cycle count to the temperature measurement module 21 to execute a patrol temperature measurement strategy. The BMS main control module 21 is installed inside the battery module. It uploads the charge / discharge power values ​​to the warning output module 23, which calculates the cell's thermal resistance based on the power. Upon receiving abnormal thermal resistance information from the warning output module 23, the BMS main control module 22 will either reduce the charge / discharge power or directly suspend charge / discharge (target charge / discharge command). The warning output module 23 has a built-in AI algorithm for comparison and judgment. It primarily receives temperature difference data uploaded by the temperature measurement module 21 and the charge / discharge power parameter P uploaded by the BMS main control module 22, calculates the thermal resistance value, and monitors whether the thermal resistance value is within the normal range. If it exceeds the preset thermal resistance value of the cell, an alarm is triggered, and the alarm signal is uploaded to the BMS main control module 22 to execute derating (charge / discharge power) operation or shutdown. The adoption of AI algorithms has improved the efficiency of big data collection and processing, and reduced data deviations caused by the timeliness of calculations.

[0027] Optionally, if the cell number of the plurality of thermal resistance cells is preset to be a, then the first temperature measured by the first temperature sensing probe corresponding to the aluminum busbar on the upper surface of the a-th thermal resistance cell is Tu,a, the second temperature measured by the second temperature sensing probe at the bottom of the a-th thermal resistance cell is Td,a, and the third temperature measured by the thermistor on the temperature-sensing water-cooling plate corresponding to the a-th thermal resistance cell is Tc,a, where a = 1, 2, 3... 104; The temperature measurement module determines the first temperature difference between the bottom of the a-th thermal resistance cell and the aluminum busbar as △T1(a)=Tu,a-Td,a based on the first temperature and the second temperature, and determines the second temperature difference between the bottom of the a-th thermal resistance cell and the surface of the temperature-sensing water-cooled plate as △T2(a)=Td,a-Tc,a based on the second temperature and the third temperature. The temperature measurement module uploads the temperature difference data to the BMS main control module. When the BMS main control module determines that the temperature difference fluctuation deviation is within the second preset value range, the BMS main control module controls the temperature measurement module to execute the preset patrol temperature measurement strategy.

[0028] As described above, the temperature measurement module uploads the temperature and temperature difference values ​​of all (thermal resistance) cells in the battery module to the early warning output module, and backs up the temperature and temperature difference values ​​in the temperature measurement module. The data can be exported separately. Since the charge / discharge cycle count of the (battery module) energy storage system is inversely proportional to the cell lifespan, and the loosening of the aluminum busbar and cell electrode welding has a time-sensitive effect, the time accuracy needs to be controlled at the second level. To save storage space and extend the lifespan of the temperature measurement module, a patrol temperature measurement strategy is designed. This patrol monitoring process reduces the pressure on the system's large data storage and also saves energy. Figure 3 As shown, taking 104 thermal resistance cells in the cell module as an example, the 104 thermal resistance cells are divided into 4 groups of 26 cells each, corresponding to 26 aluminum busbars. Adjacent thermal resistance cells are connected in series or in parallel through aluminum busbars. Depending on actual needs, adjacent thermal resistance cells can also be connected in parallel through aluminum busbars, or adjacent thermal resistance cells can be connected in series or in parallel through aluminum busbars.

[0029] When the temperature measurement module receives a temperature difference fluctuation deviation from the BMS main control module that exceeds the second preset value range, it pauses the execution of the preset patrol temperature measurement strategy. The module then controls the temperature measurement module to execute the dense patrol temperature sampling strategy within the preset patrol temperature measurement strategy. The BMS main control module uploads the charging and discharging power to the early warning output module. The predicted patrol temperature measurement strategy includes setting a patrol temperature measurement interval based on the number of charge and discharge cycles for each thermal resistance cell. The early warning output module calculates the thermal resistance value of the thermal resistance cell based on the charging and discharging power. The BMS main control module receives the thermal resistance anomaly information corresponding to the thermal resistance value and executes reduced-power charging or pauses charging and discharging. The target charging and discharging command includes reduced-power charging and paused charging and discharging. In other words, the preset patrol temperature measurement strategy is executed normally when the temperature difference (temperature difference data) of the aluminum busbar module and the aluminum busbar is within the first preset value range. If the temperature difference fluctuation deviation received from the BMS main control module exceeds the second preset value, the patrol temperature measurement strategy is paused. The temperature measurement module directly uploads the data to the early warning output module to calculate the thermal resistance value according to the dense patrol temperature sampling strategy of patrolling and sampling once every 10 seconds. If the thermal resistance value fluctuation deviation is within the normal allowable range, the original regular patrol temperature measurement strategy is restored, directly excluding the abnormal temperature difference (large thermal resistance value fluctuation deviation) from being caused by thermal resistance.

[0030] It should be noted that the early warning output module calculates the thermal resistance value of the thermally resistive battery cell based on the charging and discharging power, including: decomposing the total thermal resistance of the cell corresponding to the thermal resistance value to obtain a thermal resistance decomposition result; constructing multiple thermal resistance models of the battery cell unit based on the thermal resistance decomposition result and the charging and discharging power; and determining thermal resistance anomaly information of multiple thermally resistive battery cells based on the multiple thermal resistance models and the charging and discharging data; wherein, the early warning output module is preset to decompose the total thermal resistance of the battery cell into the cell body thermal resistance Rc, the electrical resistance of the battery cell, and the thermal resistance of the battery cell. The thermal resistance from the bottom of the cell to the aluminum busbar is Rb, the interfacial thermal resistance from the surface of the temperature-sensitive water-cooled plate to the bottom of the cell is Rs, and the welding thermal resistance between the cell terminal and the aluminum busbar is Rj. Multiple thermal resistance models are included: the separation model of the total thermal resistance component is Rz=(Rc+Rj)+Rs, the thermal resistance model from the bottom of the cell to the aluminum busbar is Rb=Rc+Rj=△T1(a) / P, the interfacial thermal resistance model from the surface of the temperature-sensitive water-cooled plate to the bottom of the cell is Rs=△T2(a) / P, and the welding thermal resistance model between the cell terminal and the aluminum busbar is Rj=Rb-Rc.

[0031] Specifically, the process for handling deviations in the thermal resistance judgment of the battery cell body Rc includes: conducting a full-lifecycle cyclic charge-discharge thermal resistance test on multiple groups of thermal resistance cells at the stated charge-discharge power and the corresponding ambient temperature; calculating a third temperature difference between the bottom and top of the thermal resistance cell, and calculating the cell body thermal resistance value of multiple groups of thermal resistance cells based on the third temperature difference value, wherein all multiple groups of cell body thermal resistance values ​​conform to a normal distribution; obtaining a normal distribution curve as the curve of change of the cell body thermal resistance value with the number of charge-discharge cycles throughout the cell body's full lifecycle, and importing a standard test cell of the thermal resistance cell throughout its full lifecycle into the warning output module based on the curve. The thermal resistance curve of the battery cell body is used as the reference Re0 for the deviation of the thermal resistance curve from the bottom of the battery cell to the aluminum busbar. The area where the measured thermal resistance value from the bottom of the battery cell to the aluminum busbar exceeds the upper deviation limit Rcs or the lower deviation limit Rcx of the thermal resistance curve of the battery cell body is defined as the thermal resistance alarm area from the bottom of the battery cell to the aluminum busbar. The area between the upper deviation limit Rcs and the lower deviation limit Rcx of the thermal resistance curve of the battery cell body is defined as the normal thermal resistance area from the bottom of the battery cell to the aluminum busbar. The fluctuation range of the thermal resistance curve deviation reference is set according to the thermal resistance curve deviation reference Re0, the upper deviation limit Rcs, and the lower deviation limit Rcx area.

[0032] Among them, such as Figure 4 As shown, Figure 4 This is a schematic diagram of the thermal resistance deviation curve. The horizontal axis represents the number of charge-discharge cycles (N), and the vertical axis represents the thermal resistance (K / W). The cell's thermal resistance Rc is determined by conducting full-lifecycle cyclic charge-discharge thermal resistance tests on multiple sets of cells. Under the same charge-discharge power P and ambient temperature (the ambient temperature corresponding to the charge-discharge power), the temperature difference between the bottom and top of the cell is calculated, thereby calculating multiple sets of cell thermal resistance values. All sets of cell thermal resistance values ​​are normally distributed, and the normal distribution curve is obtained as the curve showing the change of cell thermal resistance with the number of charge-discharge cycles throughout the cell's lifecycle. The warning output module imports the standard test cell thermal resistance curve for the entire lifecycle of the thermal resistance cell as the reference Rc0 for the deviation curve from the bottom of the cell to the aluminum busbar in the system of this invention. Figure 4 The standard test thermal resistance curve of the battery cell body is used. If the actual measured thermal resistance from the bottom of the battery cell to the aluminum busbar exceeds the upper deviation limit Rcs or the lower deviation limit Rcx of the thermal resistance curve of the battery cell body, it is an alarm area for the thermal resistance from the bottom of the battery cell to the aluminum busbar; if it is within the range of the upper deviation limit Rcs and the lower deviation limit Rcx of the thermal resistance curve of the battery cell body, it is a normal thermal resistance area from the bottom of the battery cell to the aluminum busbar. Specifically, as shown in the figure... Figure 4 The standard test thermal resistance curves of the battery cell body, the upper deviation limit of the thermal resistance curve from the bottom of the battery cell to the aluminum busbar, and the lower deviation limit of the thermal resistance curve from the bottom of the battery cell to the aluminum busbar are respectively represented by the curves.

[0033] Specifically, the process for handling deviations in the interfacial thermal resistance Rs from the surface of the temperature-sensitive water-cooled plate to the bottom of the battery cell includes: setting up a test environment where the battery cell and the water-cooled plate are in contact through thermally conductive adhesive, and conducting full-lifecycle cyclic charge-discharge thermal resistance tests using multiple sets of thermally resistive battery cells, wherein the thermally conductive adhesive is placed between the thermally resistive battery cell and the temperature-sensitive water-cooled plate; obtaining a fourth temperature difference value between the surface of the water-cooled plate and the bottom of the thermally resistive battery cell, and calculating the interfacial thermal resistance Rs based on the fourth temperature difference value and generating an Rs thermal resistance value curve for the entire lifecycle of the battery cell; importing the thermal resistance curve from the surface of the water-cooled plate to the bottom of the battery cell under the full-lifecycle standard test into the warning output module based on the Rs thermal resistance value curve, and using the thermal resistance curve from the surface of the water-cooled plate to the bottom of the battery cell as the deviation benchmark Rs0 for the thermal resistance curve from the surface of the temperature-sensitive water-cooled plate to the bottom of the battery cell. Figure 4 The standard test thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell is used to determine the deviation limit Rss of the measured thermal resistance of the cell exceeding the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell. Figure 4 The upper deviation limit of the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell (Rsx) or the lower deviation limit of the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell (Rsx) Figure 4 The area within the deviation limit of the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell is the alarm area for thermal resistance from the surface of the water-cooled plate to the bottom of the cell. The area within the deviation limit Rss of the thermal resistance curve of the cell body and the deviation limit Rsx of the thermal resistance curve of the cell body are the normal thermal resistance areas from the surface of the water-cooled plate to the bottom of the cell.

[0034] The aforementioned consistent inspection of thermal resistance cells abandons the traditional method of monitoring individual cells separately. By analyzing the mean and dispersion of the welding thermal resistance of all cells in the module, early warning of batch welding degradation can be achieved. This can identify hidden faults such as cold solder joints and fatigue cracks, enabling early warning of welding degradation and prediction of remaining life, avoiding sudden failures, extending the overall service life of the battery module, and reducing maintenance risks. A thermal resistance-lifetime correlation prediction method is adopted, establishing a correlation model between the growth rate of welding thermal resistance and cycle life, upgrading from simple fault alarms to remaining life prediction, and providing predictive maintenance capabilities. The installation of a temperature-sensing water-cooled plate enables all-round thermal resistance monitoring, ensuring cell safety without blind spots. Thermal resistance monitoring calculations can detect the presence of numerous pores between the water-cooled plate and the thermally conductive adhesive, effectively monitoring and predicting changes in thermal resistance and preventing thermal runaway.

[0035] Optionally, the warning output module generates respective thermal resistance curves based on the thermal resistance Rb from the bottom of the cell to the aluminum busbar and the thermal resistance Rs from the surface of the water-cooled plate to the bottom of the cell during the cyclic charging and discharging process, and compares the deviations with the imported standard test thermal resistance curves, including: When Rb ≤ Rcx or Rs ≤ Rsx and the charging / discharging power P remains constant, the warning output module issues an alarm, indicating a problem with the temperature acquisition of cell number a. When Rcx < Rb < Rcs or Rsx < Rs < Rss and the charging / discharging power P remains unchanged, the warning output module does not issue an alarm. When Rb≥Rcs and the temperature is within the first preset range, the warning output module issues an alarm and provides a warning about the thermal resistance problem of the aluminum busbar welding of cell number a. When Rb≥Rcs and the temperature exceeds the first preset value range, the warning output module issues an alarm and prompts a warning about the thermal resistance of the cell body and the cell cycle life of cell number a. When Rs≥Rss, the warning output module issues an alarm and indicates that the water cooling plate and the thermal conductive adhesive at the bottom of the cell number a are loose or have gaps.

[0036] In this embodiment, the preset patrol temperature measurement strategy includes: If the preset number of charge / discharge cycles for the thermal resistance battery cell is N, and the patrol temperature measurement interval is T, then: When 0 < N ≤ 500 times, T = 60 min, the temperature measuring module patrols and collects temperature once every 60 minutes; When 500 < N ≤ 1000 times, T = 40 min, the temperature measuring module patrols and collects temperature once every 40 minutes; When 1000 < N ≤ 1500 times, T = 20 min, the temperature measuring module patrols and collects temperature once every 20 minutes; When 1500 < N ≤ 2000 times, T = 10 min, the temperature measuring module patrols and collects temperature once every 10 minutes; When 2000 < N ≤ 2500 times, T = 5 min, the temperature measuring module patrols and collects temperature once every 5 minutes; When 2500 < N ≤ 3000 times, T = 1 min, the temperature measuring module patrols and collects temperature once every 1 min; When 3000 < N ≤ 5000 times, T = 0.5 min, the temperature measuring module patrols and collects temperature once every 30 seconds; When N > 5000 times, T = 0.167 min, the temperature measurement module patrols and collects temperature once every 10 seconds; Among them, patrolling and collecting temperature every 10 seconds is the dense patrol and temperature collection strategy.

[0037] It should be understood that by setting up a cell module and end plate, the cell module includes a cell unit, a temperature measurement module, a BMS main control module, and an early warning output module. The temperature measurement module collects the first temperature of each aluminum busbar, the second temperature of the bottom center of each thermal resistance cell, and the third temperature of the surface of the temperature-sensing water-cooled plate corresponding to each thermal resistance cell. Based on the first, second, and third temperatures, it determines the temperature difference value of each thermal resistance cell. When the early warning output module receives the temperature difference data uploaded by the temperature measurement module and determines that the temperature difference data is within the first preset value range, it acquires the charging and discharging data and temperature difference data of each thermal resistance cell collected by the BMS main control module, and controls the BMS main control module to upload the number of charging cycles to the temperature measurement module to execute the preset value. The system employs a patrol and temperature measurement strategy. It determines when the temperature difference fluctuation exceeds a second preset value, obtains the charging and discharging power uploaded by the BMS main control module to the early warning output module, and calculates the thermal resistance value of the thermally resistive cell based on this power. When the thermal resistance value exceeds the baseline fluctuation range of the thermal resistance curve deviation of the thermally resistive cell, the system controls the early warning output module to send an abnormal thermal resistance information to the BMS main control module. The BMS main control module then executes the corresponding target charging and discharging command. This system can break down the total thermal resistance of the cells in the battery module into three parts: the body, the interface, and the welding. Welding thermal resistance is extracted as a core monitoring indicator, accurately distinguishing different fault causes to achieve dedicated monitoring of welding degradation. This system is suitable for all energy storage scenarios, significantly reducing detection costs, decreasing maintenance frequency to some extent, and improving operating profits.

[0038] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not as limitations; therefore, other examples of exemplary embodiments may have different values.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for monitoring the thermal resistance and providing lifespan early warning of aluminum busbar welding in large battery cell modules, characterized in that, This invention relates to a large-cell module energy storage system, comprising a cell module and end plates disposed on both sides of the cell module. The cell module includes a cell unit, a temperature measurement module, a BMS main control module, and an early warning output module. Each cell unit includes multiple thermal resistance cells, multiple aluminum busbars, and a temperature-sensing water-cooled plate. The multiple aluminum busbars are disposed on the multiple thermal resistance cells and connected to the positive and negative terminals of adjacent thermal resistance cells. The temperature-sensing water-cooled plate is located at the bottom of the multiple thermal resistance cells. The thermal resistance monitoring and lifespan early warning method includes: The temperature measurement module collects the first temperature of each aluminum busbar, the second temperature of the bottom center of each thermal resistance cell, and the third temperature of the surface of the temperature-sensing water-cooled plate corresponding to each thermal resistance cell. The temperature difference value of each thermal resistance cell is determined based on the first temperature, the second temperature, and the third temperature. The temperature difference data includes the first temperature, the second temperature, the third temperature, and the temperature difference value of all collected thermal resistance cells. When the early warning output module receives the temperature difference data uploaded by the temperature measurement module and determines that the temperature difference data is within the first preset value range, it acquires the charging and discharging data of each thermal resistance cell collected by the BMS main control module and the temperature difference fluctuation deviation corresponding to the temperature difference data. The charging and discharging data includes at least one of the following for each thermal resistance cell: voltage, charging and discharging power, number of charging and discharging cycles, charging and discharging energy, or charging and discharging capacity. The BMS main control module is controlled to upload the number of charging cycles to the temperature measurement module to execute a preset patrol temperature measurement strategy, and to determine whether the temperature difference fluctuation deviation exceeds a second preset value. If so, obtain the charging and discharging power uploaded by the BMS main control module to the early warning output module, and calculate the thermal resistance value of the thermal resistance cell based on the charging and discharging power; When the thermal resistance value exceeds the thermal resistance curve deviation reference fluctuation range of the thermal resistance cell, the warning output module is controlled to send thermal resistance abnormality information corresponding to the thermal resistance value to the BMS main control module, and the BMS main control module executes the target charge and discharge command corresponding to the thermal resistance abnormality information.

2. The method for monitoring the thermal resistance and providing early warning of lifespan of aluminum busbar welding in large battery cell modules according to claim 1, characterized in that, The temperature measurement module includes a first temperature sensing probe, a second temperature sensing probe, and a thermistor. The first temperature sensing probe is disposed on the plurality of aluminum busbars, the second temperature sensing probe is disposed at the bottom of each of the thermal resistance cells, and the thermistor is located at the center of the bottom of each of the thermal resistance cells and on the surface of the temperature-sensing water-cooled plate. The first temperature sensor is used to collect the first temperature of the aluminum busbar, the second temperature sensor is used to collect the second temperature of the bottom of the plurality of thermal resistance cells, and the thermistor is used to monitor the third temperature of the surface of the temperature-sensitive water-cooled plate at the corresponding position of each thermal resistance cell.

3. The method for monitoring the welding thermal resistance and providing lifespan early warning of aluminum busbars in large battery cell modules according to claim 2, characterized in that, If the cell number of the plurality of thermal resistance cells is preset to be a, then the first temperature measured by the first temperature sensing probe corresponding to the aluminum busbar on the upper surface of the a-th thermal resistance cell is Tu,a, the second temperature measured by the second temperature sensing probe at the bottom of the a-th thermal resistance cell is Td,a, and the third temperature measured by the thermistor on the temperature-sensing water-cooled plate corresponding to the a-th thermal resistance cell is Tc,a, where a = 1, 2, 3... 104; The temperature measurement module determines the first temperature difference between the bottom of the a-th thermal resistance cell and the aluminum busbar as △T1(a)=Tu,a-Td,a based on the first temperature and the second temperature, and determines the second temperature difference between the bottom of the a-th thermal resistance cell and the surface of the temperature-sensing water-cooled plate as △T2(a)=Td,a-Tc,a based on the second temperature and the third temperature. The temperature measurement module uploads the temperature difference data to the BMS main control module. When the BMS main control module determines that the temperature difference fluctuation deviation is within the second preset value range, the BMS main control module controls the temperature measurement module to execute the preset patrol temperature measurement strategy.

4. The method for monitoring the thermal resistance and providing lifespan early warning of aluminum busbar welding in large battery cell modules according to claim 3, characterized in that, When the temperature measurement module receives a temperature difference fluctuation deviation from the BMS main control module that exceeds the second preset value range, the temperature measurement module will pause the execution of the preset patrol temperature measurement strategy. The temperature measurement module is controlled to execute the dense patrol temperature collection strategy in the preset patrol temperature measurement strategy. The BMS main control module uploads the charging and discharging power to the early warning output module. The predicted patrol temperature measurement strategy includes setting the patrol temperature measurement interval time according to the number of charge and discharge cycles of each thermal resistance cell. The early warning output module calculates the thermal resistance value of the thermal resistance cell based on the charging and discharging power. The BMS main control module receives the thermal resistance abnormality information corresponding to the thermal resistance value and executes reduced power charging or pauses charging and discharging. The target charging and discharging command includes reduced power charging and pauses charging and discharging.

5. The method for monitoring the thermal resistance and providing early warning of lifespan of aluminum busbar welding in large battery cell modules according to claim 4, characterized in that, The early warning output module calculates the thermal resistance value of the thermal resistance cell based on the charging and discharging power, including: The total thermal resistance of the battery cell corresponding to the thermal resistance value is broken down to obtain the thermal resistance breakdown result. Based on the thermal resistance breakdown results and the charge / discharge power, multiple thermal resistance models of the battery cell are constructed. Based on the multiple thermal resistance models and the charge / discharge data, thermal resistance anomaly information of multiple thermal resistance cells is determined. The pre-set early warning output module breaks down the total thermal resistance of the battery cell into the thermal resistance of the battery cell body Rc, the thermal resistance from the bottom of the battery cell to the aluminum busbar Rb, the interface thermal resistance from the surface of the temperature-sensing water-cooled plate to the bottom of the battery cell Rs, and the welding thermal resistance between the battery cell electrode and the aluminum busbar Rj. Multiple thermal resistance models are included: the separation model of the total thermal resistance component is Rz=(Rc+Rj)+Rs, the thermal resistance model from the bottom of the cell to the aluminum busbar is Rb=Rc+Rj=△T1(a) / P, the interface thermal resistance model from the surface of the temperature-sensing water-cooled plate to the bottom of the cell is Rs=△T2(a) / P, and the welding thermal resistance model between the cell electrode and the aluminum busbar is Rj=Rb-Rc.

6. The method for monitoring the thermal resistance and providing early warning of lifespan of aluminum busbar welding in large battery cell modules according to claim 5, characterized in that, The process for handling deviations in the determination of the thermal resistance Rc of the battery cell includes: Multiple sets of thermal resistance cells were subjected to full-life-cycle cyclic charge-discharge thermal resistance testing at the charge-discharge power and the ambient temperature corresponding to the charge-discharge power. Calculate the third temperature difference between the bottom and top of the thermal resistance cell, and calculate the cell body thermal resistance values ​​of multiple sets of thermal resistance cells based on the third temperature difference value, wherein all multiple sets of cell body thermal resistance values ​​conform to a normal distribution. Obtain a normal distribution curve as the curve of change of the thermal resistance value of the battery cell body with the number of charge and discharge cycles throughout the entire life cycle of the battery cell body, and import the standard test thermal resistance curve of the battery cell body throughout the entire life cycle into the warning output module according to the curve of change. The standard test cell body thermal resistance curve is used as the thermal resistance curve deviation benchmark Re0 from the bottom of the cell to the aluminum busbar. The area where the measured thermal resistance value from the bottom of the cell to the aluminum busbar exceeds the upper deviation limit Rcs or the lower deviation limit Rcx of the cell body thermal resistance curve is defined as the thermal resistance alarm area from the bottom of the cell to the aluminum busbar. The area between the upper deviation limit Rcs and the lower deviation limit Rcx of the cell body thermal resistance curve is defined as the normal thermal resistance area from the bottom of the cell to the aluminum busbar. The fluctuation range of the thermal resistance curve deviation benchmark is set according to the thermal resistance curve deviation benchmark Re0, the upper deviation limit Rcs, and the lower deviation limit Rcx area.

7. The method for monitoring the welding thermal resistance and providing lifespan early warning of aluminum busbars in large battery cell modules according to claim 6, characterized in that, The process for handling deviations in judging the interfacial thermal resistance Rs from the surface of the temperature-sensitive water-cooled plate to the bottom of the battery cell includes: A test environment was set up for the contact between the battery cell and the water-cooled plate through thermally conductive adhesive, and a full life cycle charge-discharge thermal resistance test was carried out using multiple sets of thermally resistive battery cells. The thermally conductive adhesive was placed between the thermally resistive battery cell and the temperature-sensitive water-cooled plate. Obtain the fourth temperature difference between the surface of the water-cooled plate and the bottom of the thermally resistive cell, and calculate the interface thermal resistance Rs based on the fourth temperature difference to generate the Rs thermal resistance curve for the entire life cycle of the cell. Based on the Rs thermal resistance curve, the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell under the full life cycle standard test of the thermal resistance cell is imported into the early warning output module, and the thermal resistance curve from the surface of the water-cooled plate to the bottom of the cell is used as the deviation benchmark Rs0 of the thermal resistance curve from the surface of the temperature-sensing water-cooled plate to the bottom of the cell. The area where the measured thermal resistance of the battery cell exceeds the upper deviation limit Rss of the thermal resistance curve from the surface of the water-cooled plate to the bottom of the battery cell or the lower deviation limit Rsx of the thermal resistance curve from the surface of the water-cooled plate to the bottom of the battery cell is identified as the thermal resistance alarm area from the surface of the water-cooled plate to the bottom of the battery cell. The area within the upper deviation limit Rss of the thermal resistance curve of the battery cell body and the lower deviation limit Rsx of the thermal resistance curve of the battery cell body is identified as the normal thermal resistance area from the surface of the water-cooled plate to the bottom of the battery cell.

8. The method for monitoring the welding thermal resistance and providing lifespan early warning of aluminum busbars in large battery cell modules according to claim 7, characterized in that, The warning output module generates thermal resistance curves based on the thermal resistance Rb from the bottom of the battery cell to the aluminum busbar and the thermal resistance Rs from the surface of the water-cooled plate to the bottom of the battery cell during the cyclic charging and discharging process. It then compares the deviations with the imported standard test thermal resistance curves, including: When Rb ≤ Rcx or Rs ≤ Rsx and the charging / discharging power P remains constant, the warning output module issues an alarm, indicating a problem with the temperature acquisition of cell number a. When Rcx < Rb < Rcs or Rsx < Rs < Rss and the charging / discharging power P remains unchanged, the warning output module does not issue an alarm. When Rb≥Rcs and the temperature is within the first preset range, the warning output module issues an alarm and provides a warning about the thermal resistance problem of the aluminum busbar welding of cell number a. When Rb≥Rcs and the temperature exceeds the first preset value range, the warning output module issues an alarm and prompts a warning about the thermal resistance of the cell body and the cell cycle life of cell number a. When Rs≥Rss, the warning output module issues an alarm and indicates that the water cooling plate and the thermal conductive adhesive at the bottom of the cell number a are loose or have gaps.

9. The method for monitoring the welding thermal resistance and providing lifespan early warning of aluminum busbars in large battery cell modules according to claim 2, characterized in that, The large battery cell module energy storage system also includes a housing, a steel strip, and a temperature sensing socket. The housing is disposed on the upper surface of the battery cell module and covers the end plate. The two ends of the steel strip are respectively connected to the two end plates. The steel strip is attached to the battery cell unit. The temperature sensing socket is disposed at the bottom of the thermal resistance battery cell. The second temperature sensing probe is connected to the temperature measurement module through the temperature sensing socket.

10. The method for monitoring the welding thermal resistance and providing lifespan early warning of aluminum busbars in large battery cell modules according to claim 1, characterized in that, The preset patrol temperature measurement strategy includes: If the preset number of charge / discharge cycles for the thermal resistance battery cell is N, and the patrol temperature measurement interval is T, then: When 0 < N ≤ 500 times, T = 60 min, the temperature measuring module patrols and collects temperature once every 60 minutes; When 500 < N ≤ 1000 times, T = 40 min, the temperature measuring module patrols and collects temperature once every 40 minutes; When 1000 < N ≤ 1500 times, T = 20 min, the temperature measuring module patrols and collects temperature once every 20 minutes; When 1500 < N ≤ 2000 times, T = 10 min, the temperature measuring module patrols and collects temperature once every 10 minutes; When 2000 < N ≤ 2500 times, T = 5 min, the temperature measuring module patrols and collects temperature once every 5 minutes; When 2500 < N ≤ 3000 times, T = 1 min, the temperature measuring module patrols and collects temperature once every 1 min; When 3000 < N ≤ 5000 times, T = 0.5 min, the temperature measuring module patrols and collects temperature once every 30 seconds; When N > 5000 times, T = 0.167 min, the temperature measurement module patrols and collects temperature once every 10 seconds; Among them, patrolling and collecting temperature every 10 seconds is the dense patrol and temperature collection strategy.

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