Low-voltage battery system bms state diagnosis method, device, equipment and storage medium

Abstract

The application provides a low-voltage battery system BMS state diagnosis method, device and equipment and a storage medium, and belongs to the technical field of batteries. The method comprises the following steps: placing a low-voltage battery system to be detected in a preset initial state; controlling a power switching device to make a main circuit generate charging current and discharging current respectively, and collecting temperature change data of a shunt during current loading and after current stopping; calculating a temperature rise characteristic parameter representing the working state of the BMS based on the temperature change data; matching the temperature change data and the temperature rise characteristic parameter with a preset judgment rule, and determining the corresponding fault type or normal state of the BMS according to the matching result. The temperature rise characteristic parameter is calculated based on the temperature change data, and state analysis is performed in combination with the temperature change data. Compared with the mode of judging only by voltage and current parameters, the working state of the BMS can be comprehensively evaluated by using the temperature rise characteristic, and the accuracy of BMS state diagnosis and the abnormal recognition ability are improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and in particular relates to a method, apparatus, device and storage medium for BMS state diagnosis of low-voltage battery systems. Background Technology

[0002] With the development of new energy technologies, low-voltage battery systems are widely used in energy storage devices, low-voltage power equipment, and vehicle auxiliary power supply systems. As a crucial component of low-voltage battery systems, the Battery Management System (BMS) is typically used to monitor battery status, control charge and discharge, and provide safety protection. Among these components, the main circuit and power switching devices within the BMS directly affect the charging and discharging performance and operational safety of the battery system. Therefore, effectively monitoring the operating status of the BMS is of great significance.

[0003] Currently, BMS condition monitoring typically employs parameters such as voltage, current, and temperature to determine if any abnormalities exist in the battery system. For example, the operating status of the battery system is assessed by detecting changes in main circuit current, battery voltage, and temperature. However, in practical applications, BMS fault types are diverse, and relying solely on a single parameter is insufficient to accurately distinguish between different faults. Summary of the Invention

[0004] In view of this, the present invention provides a method, apparatus, device and storage medium for diagnosing the condition of a low-voltage battery system (BMS) to improve the accuracy of fault detection.

[0005] A first aspect of the present invention provides a method for diagnosing the condition of a low-voltage battery system (BMS), comprising: a method for diagnosing the condition of a low-voltage battery system (BMS), characterized in that the BMS includes a main circuit, power switching devices disposed in the main circuit, and a shunt, the method comprising: Place the low-voltage battery system to be tested into a preset initial state; By controlling the power switching device, the main circuit generates charging current and discharging current respectively, and the temperature change data of the shunt is collected during the current loading process and after the current stops. Based on the temperature change data, calculate the temperature rise characteristic parameters that characterize the working state of the BMS; The temperature change data and the temperature rise characteristic parameters are matched with preset judgment rules, and the fault type or normal state corresponding to the BMS is determined based on the matching result.

[0006] A second aspect of the present invention provides a low-voltage battery system BMS state diagnostic device, wherein the BMS includes a main circuit, power switching devices disposed in the main circuit, and a shunt, and the device includes: An initialization module is used to place the low-voltage battery system to be tested into a preset initial state. The temperature change data acquisition module is used to control the power switching device to generate charging current and discharging current in the main circuit, and to acquire the temperature change data of the shunt during current loading and after current stopping. The temperature rise characteristic parameter calculation module is used to calculate the temperature rise characteristic parameters that characterize the working state of the BMS based on the temperature change data. The status monitoring module is used to match the temperature change data and the temperature rise characteristic parameters with preset judgment rules, and determine the fault type or normal state corresponding to the BMS based on the matching result.

[0007] A third aspect of the present invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the low-voltage battery system BMS state diagnosis method as described in the first aspect above.

[0008] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the low-voltage battery system BMS state diagnosis method as described in the first aspect above.

[0009] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: This invention controls the power switching devices in the BMS (Battery Management System) to enable the low-voltage battery system to perform charging and discharging processes separately, and collects temperature change data of the shunt during current loading and after current cessation, thereby obtaining the temperature response characteristics of the BMS during operation. Based on the collected temperature change data, temperature rise characteristic parameters characterizing the BMS's operating state are calculated, and state analysis is performed by combining the temperature change data and temperature rise characteristic parameters. Compared with methods that rely solely on single voltage and current parameters for judgment, this method can comprehensively evaluate the BMS's operating state using temperature change information during operation, improving the accuracy and reliability of BMS state diagnosis. Furthermore, by acquiring state information during the charging and discharging processes and the temperature change process after current cessation, the method can analyze the dynamic temperature rise characteristics of the BMS during operation, thereby improving the ability to identify abnormal BMS states. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of a low-voltage battery system BMS state diagnosis method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the BMS structure in a low-voltage lithium battery system provided in an embodiment of the present invention; Figure 3 This is a graph showing the change of shunt temperature with test time under different fault conditions provided in the embodiments of the present invention; Figure 4 This is a schematic diagram of a low-voltage battery system BMS status diagnostic device provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0012] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the present invention. However, those skilled in the art will recognize that the present application may be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted to avoid unnecessary detail that could obscure the description of the present application.

[0013] The technical solution of the present invention will be illustrated below through specific embodiments.

[0014] Reference Figure 1 The diagram illustrates a low-voltage battery system (BMS) status diagnostic method provided by an embodiment of the present invention. This method can be executed by a low-voltage battery system (BMS) status diagnostic device, which can be implemented in hardware and / or software and can be configured in an electronic device.

[0015] The low-voltage battery system is a 24V / 48V low-voltage lithium battery system. The BMS includes a main circuit, power switching devices and shunts installed in the main circuit. The main circuit is used to realize the power transfer between the low-voltage battery system and the external charging and discharging circuit. The power switching devices are used to control the on and off state of the main circuit to realize the switching between the charging and discharging processes. The shunt is installed in the main circuit to detect the current state in the main circuit and can obtain the temperature change data of the main circuit under different operating conditions through the temperature detection module.

[0016] In this embodiment, the diagnostic method achieves state detection based on the thermal response characteristics of the BMS main circuit under the action of current. Specifically, according to Joule's law Q=I... 2 During the test, a constant current of a preset amplitude is applied to a closed loop consisting of a shunt, power switching devices, and the main circuit conductive structure. The resistive losses in the loop are converted into heat, causing the shunt to generate a corresponding temperature rise response. Under the condition that the test current amplitude and duration are fixed, the temperature rise change of the shunt can reflect the change in the overall impedance of the BMS main circuit.

[0017] Under normal circumstances, when the BMS operates under preset current conditions, the shunt temperature change process and the temperature recovery process after the current is stopped follow preset patterns. When abnormalities occur in the BMS main circuit impedance, the state of the power switching devices, or the temperature acquisition status, it will cause changes in the shunt temperature rise amplitude, the consistency of charging and discharging temperature rises, the temperature change trend after the current is stopped, or the shape of the temperature change curve. Therefore, by comparing the temperature rise response during charging and discharging, the consistency of the circuit state under different current directions can be characterized; by analyzing the temperature recovery process after the current stops, the thermal state changes of the power switching devices after they are turned off can be determined; and by analyzing the stability of the temperature change curve, it can help determine whether there are any abnormalities in the temperature acquisition channel.

[0018] Based on the above principles, this embodiment collects temperature response data during BMS operation by setting a test condition with fixed current and fixed loading time, and extracts temperature rise characteristic parameters to achieve diagnosis of BMS working status.

[0019] In this embodiment, the low-voltage battery system (BMS) status diagnosis method is based on the thermal response characteristics of the main circuit under different operating conditions to achieve fault detection. Since the conductive components, connecting components, and power switching devices in the BMS main circuit generate power losses and corresponding temperature rise responses under current, the temperature change process of the shunt can reflect the operating status of the BMS main circuit. Under normal circumstances, when the BMS operates under preset current conditions, the temperature change process of the shunt and the temperature recovery process after the current is stopped exhibit certain patterns. When the impedance of the BMS main circuit, the state of the power switching devices, or the temperature acquisition status becomes abnormal, it will cause changes in the shunt temperature rise amplitude, the consistency of charge and discharge temperature rise, the temperature change trend after the current is stopped, or the shape of the temperature change curve. Therefore, by collecting the temperature change data of the shunt during current loading and after current cessation, and extracting temperature rise characteristic parameters based on the temperature change data, the operating status of the BMS can be diagnosed.

[0020] like Figure 1 As shown, the method may specifically include the following steps: S101. Place the low-voltage battery system to be tested into a preset initial state.

[0021] Before performing BMS status diagnosis, the low-voltage battery system to be tested is first initialized to a preset initial state to reduce the impact of differences in the initial state of the system on subsequent test results.

[0022] The preset initial state can be a static state where the low-voltage battery system is not undergoing charging or discharging operations. In this state, there is no operating current in the BMS main circuit, and the shunt temperature is stable.

[0023] In practice, the current ambient temperature and shunt temperature information can be collected, and the current status in the BMS main circuit can be detected. When it is determined that the main circuit is in a no-current state and the shunt temperature meets the preset conditions with respect to the ambient temperature, the low-voltage battery system is considered to have reached the preset initial state and will proceed to the subsequent testing process.

[0024] S102. By controlling the power switching device, the main circuit generates charging current and discharging current respectively, and collects the temperature change data of the shunt during the current loading process and after the current stops.

[0025] After the low-voltage battery system is in the preset initial state, the power switching devices in the main circuit are controlled by the BMS to make the main circuit enter the charging state and the discharging state in sequence.

[0026] Specifically, the temperature change data of the shunt is continuously collected during the charging and discharging current loading processes; after the charging and discharging currents stop (load), the temperature change data of the shunt under no current loading is collected.

[0027] That is, firstly, the corresponding power switching device is turned on to generate a charging current in the main circuit. During the charging current loading process, the temperature change data of the shunt is continuously collected by the temperature detection module. After the charging test is completed, the charging current is stopped, and the temperature change data of the shunt under no current condition is collected again.

[0028] Subsequently, by controlling the power switching device, a discharge current is generated in the main circuit, and the temperature change data of the shunt is continuously collected during the discharge current loading process; after the discharge test is completed, the discharge current is stopped, and the temperature change data of the shunt in the state of no current is collected.

[0029] The above method can be used to obtain the complete temperature response process of the shunt under current loading and after current cessation.

[0030] Optionally, the charging current and the discharging current are constant currents with equal amplitudes, and the time interval between the moment when the charging current stops and the moment when the discharging current starts to load is a preset resting time.

[0031] Specifically, during the charging test, the power switching device is controlled to generate a constant amplitude charging current in the main circuit, and the charging current is kept stable within a preset charging time. After the charging test is completed, the power switching device is controlled to stop outputting the charging current, causing the main circuit to enter a current-free state.

[0032] After the charging current is stopped, a preset resting time is maintained to allow the shunt to recover its temperature in a current-free state, thereby reducing the impact of the heat generated during the charging process on the temperature detection results of the subsequent discharge test.

[0033] After a preset resting time is reached, the power switching device is controlled to generate a discharge current in the main circuit, wherein the amplitude of the discharge current is equal to the amplitude of the charging current and remains constant within the preset discharge time.

[0034] By setting the same charging and discharging current amplitude and setting a preset resting time between the cessation of charging current and the commencement of discharging current, the charging and discharging tests can have the same current loading conditions, and the impact of heat accumulation in the previous test stage on the temperature change data in the subsequent test stage can be reduced, thereby improving the accuracy of obtaining temperature rise characteristic parameters based on temperature change data.

[0035] S103. Calculate the temperature rise characteristic parameters that characterize the working state of the BMS based on temperature change data.

[0036] Based on the temperature change data collected in step S102, the temperature response of the shunt at different operating stages is analyzed, and the temperature rise characteristic parameters used to characterize the working state of the BMS are calculated.

[0037] Among them, the temperature rise characteristic parameter can be used to describe the degree of temperature change of the shunt during the current application process and the temperature recovery characteristics after the current stops. For example, the corresponding temperature rise characteristic parameter can be obtained based on information such as the temperature rise amplitude, temperature change trend, and temperature change rate during the temperature change process.

[0038] By extracting features from temperature change data, scattered temperature change information can be converted into feature quantities that reflect the working status of the BMS, providing a data foundation for subsequent status judgment.

[0039] S104. Match the temperature change data and temperature rise characteristic parameters with the preset judgment rules, and determine the fault type or normal state corresponding to the BMS based on the matching results.

[0040] After obtaining the temperature change data and the corresponding temperature rise characteristic parameters, the above data is matched and analyzed with the pre-set judgment rules.

[0041] Specifically, the current operating status of the BMS can be comprehensively judged based on the changing trend of the temperature change data and whether the temperature rise characteristic parameters meet preset conditions. When the matching result meets the conditions corresponding to the normal state, it is determined that the BMS is in a normal working state; when the matching result meets the conditions corresponding to the abnormal state, it is determined that the BMS has a corresponding abnormal state.

[0042] Through the above steps, this embodiment can utilize the temperature change information of the shunt during BMS operation to diagnose the working status of the BMS and achieve effective detection of the BMS status of the low-voltage battery system.

[0043] This invention controls the power switching devices in the BMS (Battery Management System) to enable the low-voltage battery system to perform charging and discharging processes separately, and collects temperature change data of the shunt during current loading and after current cessation, thereby obtaining the temperature response characteristics of the BMS during operation. Based on the collected temperature change data, temperature rise characteristic parameters characterizing the BMS's operating state are calculated, and state analysis is performed by combining the temperature change data and temperature rise characteristic parameters. Compared with methods that rely solely on single voltage and current parameters for judgment, this method can comprehensively evaluate the BMS's operating state using temperature change information during operation, improving the accuracy and reliability of BMS state diagnosis. Furthermore, by acquiring state information during the charging and discharging processes and the temperature change process after current cessation, the method can analyze the dynamic temperature rise characteristics of the BMS during operation, thereby improving the ability to identify abnormal BMS states.

[0044] In an optional embodiment, before performing state diagnostics on the low-voltage battery system BMS, the low-voltage battery system to be tested is first initialized to place it in a preset initial state. Placing the low-voltage battery system to be tested in the preset initial state includes: Collect ambient temperature and the initial temperature of the shunt, and detect the static current of the BMS main circuit; when the static current is zero and the temperature difference between the initial temperature of the shunt and the ambient temperature is less than the preset temperature difference threshold, determine that the low-voltage battery system is in the preset initial state.

[0045] Specifically, the ambient temperature of the current test environment is collected by the temperature detection module, and the initial temperature of the shunt in the BMS main circuit is also collected. At the same time, the quiescent current in the BMS main circuit is detected by the current detection module to determine whether the low-voltage battery system is currently in a no-current operating state.

[0046] When the quiescent current of the BMS main circuit is detected to be zero, it indicates that the main circuit is not currently undergoing charging or discharging operations. Furthermore, the initial temperature of the shunt is compared with the ambient temperature. When the temperature difference between the two is less than a preset temperature difference threshold, it indicates that the shunt temperature has essentially reached the same level as the ambient temperature and has not been affected by the heat generated during previous operation. The preset temperature difference threshold can be 5℃. When the quiescent current is zero and the temperature difference between the initial temperature of the shunt and the ambient temperature meets the preset conditions, the low-voltage battery system is determined to have reached the preset initial state and enters the subsequent charge and discharge test process.

[0047] By assessing the current state of the low-voltage battery system and the initial temperature state of the shunt before testing, the impact of the initial current and initial temperature differences on subsequent temperature change data acquisition results can be reduced, thereby improving the accuracy of temperature rise characteristic parameter calculation.

[0048] In an optional embodiment, to ensure consistent test conditions for the charging and discharging tests, the charging and discharging currents are set to constant currents with the same amplitude. Both the charging and discharging currents have an amplitude of 390A to 410A and a duration of 10 seconds.

[0049] Specifically, during the charging test, a constant charging current of 400A is generated in the BMS main circuit by controlling the power switching devices and continuously applied for 10 seconds to collect the temperature change data of the shunt during the charging current application. When the current is below 390A, the temperature rise difference caused by various latent faults may be less than 3℃, which is difficult to reflect by ambient temperature fluctuations and inherent errors of the devices, making it impossible to effectively distinguish faults; when the current is above 410A, the low-voltage BMS will inevitably trigger hardware overcurrent and overtemperature protection, forcing the test to be interrupted, and easily causing damage to power devices. At the critical time level, when the test time is less than 10s, the heat in the circuit has not formed a steady-state accumulation, and the thermodynamic characteristics of different faults cannot be distinguished; when the test time exceeds 10s, the heat is continuously conducted to the battery cell, causing irreversible thermal damage to the battery cell. At the same time, the temperature rise of the shunt enters a saturation state, the temperature rise difference of the fault is leveled out, and the ability to detect and distinguish faults is lost. Therefore, the application time was determined to be 10s.

[0050] After the charging test is completed and a preset resting time has elapsed, the power switching devices are controlled to generate a constant discharge current of 400A in the BMS main circuit, which is continuously applied for 10 seconds to collect the temperature change data of the shunt during the discharge current's action. By setting the same charge and discharge test current for the same amplitude and duration, the charging and discharging test processes can be made to have the same current loading conditions, facilitating the calculation of temperature rise characteristic parameters based on temperature change data during the charging and discharging process, and improving the consistency of temperature rise characteristic comparisons across different test stages.

[0051] In an optional embodiment, to characterize the operating state of the low-voltage battery system BMS under different current directions, the temperature rise characteristic parameters include charging temperature rise characteristic parameters, discharging temperature rise characteristic parameters, and charging / discharging temperature rise consistency characteristic parameters.

[0052] Temperature rise characteristic parameters characterizing the BMS operating state are calculated based on temperature change data, including: The charging temperature rise characteristic parameters are determined based on the temperature change data during the charging current loading process; the discharging temperature rise characteristic parameters are determined based on the temperature change data during the discharging current loading process; and the charging and discharging temperature rise consistency characteristic parameters are determined based on the difference between the charging temperature rise characteristic parameters and the discharging temperature rise characteristic parameters.

[0053] Specifically, during the charging current loading process, the temperature change data of the shunt is continuously collected, and the charging temperature rise characteristic parameters are determined based on the temperature change before and after the charging current loading; during the discharging current loading process, the temperature change data of the shunt is continuously collected, and the discharging temperature rise characteristic parameters are determined based on the temperature change before and after the discharging current loading.

[0054] Furthermore, based on the difference between the charging temperature rise characteristic parameters and the discharging temperature rise characteristic parameters, charging and discharging temperature rise consistency characteristic parameters are determined. These parameters characterize whether the temperature rise response of the BMS is consistent under the influence of current in both the charging and discharging directions.

[0055] For example, the temperature change of the shunt during charging and discharging can be calculated separately to obtain the corresponding charging temperature rise characteristic parameters and discharging temperature rise characteristic parameters. Furthermore, by calculating the difference, ratio, or other parameters characterizing the degree of difference between these two parameters, the consistency characteristic parameters of the charging and discharging temperature rise can be obtained. The above method can simultaneously obtain the temperature rise response characteristics of the BMS under different current directions, providing a data foundation for subsequent judgment of the BMS working status and identification of abnormal states based on temperature rise characteristic parameters.

[0056] In an optional embodiment, to further characterize the thermal state changes after the BMS stops operating, the temperature rise characteristic parameters include charging recovery characteristic parameters and discharging recovery characteristic parameters. The temperature rise characteristic parameters characterizing the BMS operating state are calculated based on temperature change data, and further include: Based on the temperature change trend of the shunt after the charging current stops over time, the charging recovery characteristic parameters are determined; based on the temperature change trend of the shunt after the discharging current stops over time, the discharging recovery characteristic parameters are determined; both the charging recovery characteristic parameters and the discharging recovery characteristic parameters include the temperature drop rate, the temperature change trend, or the temperature change amount within a preset time.

[0057] The temperature recovery characteristic parameters can include the rate of temperature decrease, the trend of temperature change, and the amount of temperature change within a preset time. By analyzing the temperature change process after the current stops, the heat release state of the shunt after the current is stopped can be obtained.

[0058] For example, the temperature drop rate can be calculated based on the temperature change of the shunt within a preset time period, or the temperature change trend can be determined based on the direction of temperature change over time, and the temperature change within the preset time period can be used as a temperature recovery characteristic parameter.

[0059] By introducing the temperature recovery characteristic parameter after the current stops, the temperature recovery state after the BMS stops applying current can be characterized, thus providing a basis for subsequent BMS working status diagnosis based on the temperature rise characteristic parameter.

[0060] In an optional embodiment, determining the fault type or normal state corresponding to the BMS based on the matching result includes: When the charging temperature rise characteristic parameter or the discharging temperature rise characteristic parameter exceeds the preset temperature rise threshold, it is determined that there is a main circuit abnormality in the BMS; when the charging and discharging temperature rise consistency characteristic parameter meets the preset consistency abnormality condition, it is determined that there is a charging and discharging temperature rise consistency abnormality in the BMS; when the temperature recovery characteristic parameter does not meet the preset temperature recovery change law, it is determined that there is an abnormal conduction fault in the power switching device of the BMS; when the temperature change curve corresponding to the temperature change data is inconsistent with the preset temperature change law, and the main circuit current status is normal, it is determined that there is a temperature acquisition abnormality in the BMS; when multiple temperature rise characteristic parameters simultaneously meet the corresponding abnormality judgment conditions, it is determined that there is a coupling fault in the BMS.

[0061] Specifically, the operating status of the BMS can be diagnosed based on the changes in different temperature rise characteristic parameters. When the charging temperature rise characteristic parameter or the discharging temperature rise characteristic parameter exceeds the preset temperature rise threshold, it indicates that the temperature rise amplitude of the shunt is abnormal during the current loading process. This may be due to the additional impedance generated by the connecting parts, conductive parts or other circuit structures in the main circuit, leading to increased heat generation. Therefore, it is determined that there is an abnormality in the main circuit of the BMS.

[0062] When the charging and discharging temperature rise consistency characteristic parameter meets the preset consistency anomaly condition, such as the charging and discharging temperature rise consistency characteristic parameter being greater than the preset consistency threshold (3℃), it indicates that there is a significant difference in the temperature rise response corresponding to the charging process and the discharging process, that is, the thermal response of the charging path and the discharging path are inconsistent. Therefore, it is determined that there is a charging and discharging temperature rise consistency anomaly in the BMS.

[0063] When the temperature recovery characteristic parameters do not meet the preset temperature recovery change law, it indicates that the temperature recovery process of the shunt is abnormal after the current is stopped. For example, the temperature does not drop as expected or the rate of temperature drop is abnormal after the current is stopped. At this time, it can be determined that there is an abnormal conduction fault of the power switching device in the BMS.

[0064] When the shape of the temperature change curve corresponding to the temperature change data is inconsistent with the preset temperature change law, and the detected main circuit current status is normal, it indicates that the abnormal temperature change is not caused by the actual current change. Therefore, it can be determined that there is an abnormality in the temperature acquisition of the BMS.

[0065] Furthermore, when multiple temperature rise characteristic parameters simultaneously meet the corresponding anomaly judgment conditions, it indicates that multiple abnormal factors may exist in the BMS at the same time, thus confirming that there is a coupling fault in the BMS.

[0066] Using the above methods, different abnormal states of the BMS can be distinguished based on the temperature rise characteristics during charging and discharging, the temperature recovery characteristics after the current is stopped, and the temperature change curve characteristics, thereby enabling the diagnosis of the BMS's working status.

[0067] To further illustrate the diagnostic process and effect of the low-voltage battery system BMS state diagnosis method of the present invention, the following description is based on a specific test scenario.

[0068] Please refer to Figure 2 This diagram illustrates a BMS structure in a low-voltage lithium battery system provided by an embodiment of the present invention. Figure 2 As shown, the BMS includes a metal plate 21, a PCB board 22, a shunt 23, a thermistor 24, and other electronic components. The power switching device is mounted on the PCB board 22, but is not shown in the figure.

[0069] The thermistor 24 is attached to the surface of the shunt 23 to detect the temperature change of the shunt 23 under different operating conditions. Optionally, the thermistor 24 can be a negative temperature coefficient thermistor (NTC), and the shunt 23 can be made of manganese-copper alloy. The shunt 23 is connected in series in the current loop to be measured. In this embodiment, the shunt 23 is located in the main negative terminal path of the low-voltage battery system to obtain temperature response data under the action of the main circuit current.

[0070] Operating conditions during testing: ambient temperature 25℃, battery SOC maintained at 50%, no BMS fault alarms. Before the test began, the initial temperature of the shunt was measured at 26℃, with a temperature difference of 1℃ from the ambient temperature, which is less than the preset temperature difference threshold of 5℃; the main circuit static current was 0A, meeting the preset initial state conditions.

[0071] Example 1 (BMS in normal working condition): First, by controlling the power switching devices, a constant charging current of 400A was applied to the BMS main circuit for 10 seconds. During the test, the temperature change data of the shunt was continuously collected.

[0072] After the charging test is completed, the charging current is stopped, and the circuit enters a no-current state. Temperature change data during the shunt's recovery process is collected. Subsequently, after a preset resting time, the power switching devices are controlled to apply a constant discharge current of 400A to the main circuit for 10 seconds.

[0073] The test results show that: During the charging process, the shunt temperature rose from 26℃ to 43℃, with a temperature rise of 17℃. The temperature change curve was smooth and there were no abnormal fluctuations. After the charging current is stopped, the shunt temperature gradually decreases, and after standing still for 5 seconds, the temperature drops to 36℃. During the discharge process, the shunt temperature rose from 36℃ to 52℃, with a temperature rise of 16℃. The temperature rise difference during charging and discharging is 1℃, which meets the preset temperature rise consistency judgment condition; Meanwhile, the highest temperature during the entire test was lower than the preset safe temperature threshold, and the temperature recovery process after charging and discharging followed the preset change pattern.

[0074] Based on a comprehensive assessment of the temperature rise amplitude, the consistency of temperature rise during charging and discharging, and the temperature recovery characteristic parameters, the BMS is in normal working condition.

[0075] Example 2 (Single Abnormal State): Abnormality 1: Main circuit abnormality In this test scenario, the contact impedance at the main circuit connection point was increased to simulate abnormal circuit contact. A 400A constant current charge-discharge pulse test was used. The test results showed that the shunt temperature rise was significantly higher than the normal state (temperature rise: 30℃), the temperature rose rapidly, and exceeded the preset temperature rise threshold (70℃).

[0076] Because an increase in loop impedance leads to increased resistance loss under the same test current conditions, resulting in a larger temperature rise in the shunt, the abnormal temperature rise amplitude indicates a main loop anomaly in the BMS. This anomaly may be caused by factors such as abnormal copper busbar connection, loose fasteners, poor crimping (preventing heat from being dissipated through heat conduction via the metal plate), or abnormal conductive path.

[0077] Anomaly 2: Temperature sampling anomaly In this test scenario, the simulated temperature acquisition channel malfunctioned.

[0078] During the test, the main circuit was loaded with a charging current of 400A and a discharging current of 400A, but the temperature rise of the shunt was less than 5℃, indicating that the temperature change data of the shunt remained basically stable and did not reflect the temperature rise response corresponding to the actual current loading process. Therefore, the anomaly may be caused by a faulty thermistor connection, a faulty sampling circuit, or a faulty temperature acquisition circuit, rendering the temperature sampling data invalid.

[0079] Anomaly 3: Abnormal consistency of charging and discharging temperature rise In this test scenario, the paths corresponding to the simulated charging and discharging directions were inconsistent, which was an anomaly.

[0080] The test results show that: The shunt temperature rises to 24℃ during charging. The shunt temperature rises by 9°C during the discharge process; The charging temperature rise was 24°C, and the discharging temperature rise was 9°C, with a temperature difference of 15°C, exceeding the preset consistency threshold of 3°C. Therefore, the charging and discharging temperature rise consistency characteristic parameter is determined to meet the preset consistency anomaly condition. Since the charging and discharging processes use the same amplitude and duration of test current, but the temperature rise response differs significantly, the BMS is determined to have a charging and discharging temperature rise consistency anomaly. This anomaly may be caused by differences in power switching device parameters, connection status, or loop impedance in the charging and discharging path.

[0081] Abnormality 4: MOSFET turn-off failure and leakage current fault In this test scenario, the simulated power switching device shuts off abnormally.

[0082] After the charge and discharge test was completed and the current was stopped, it was found that the main circuit current had returned to zero, but the shunt temperature did not decrease as preset, but continued to rise.

[0083] After the current is stopped, the shunt should normally enter a natural heat dissipation process. However, the continued temperature rise indicates that an abnormal heat source still exists. Therefore, based on the abnormal temperature recovery characteristic parameters, it is determined that there is an abnormal conduction fault in the power switching device of the BMS. This abnormality may be caused by factors such as incomplete turn-off of the power switching device or abnormal leakage current.

[0084] Anomaly 5: Abnormal interference in the acquired signal In this test scenario, the main circuit current was kept stable. During the test, it was found that the shunt temperature readings fluctuated irregularly, and the temperature change curve showed obvious jumps.

[0085] Since the actual temperature rise of the shunt under constant current conditions should remain continuous, but the collected data showed abnormal fluctuations, it was determined that there was an anomaly in the temperature acquisition of the BMS.

[0086] Example 3 (Multiple Fault Coupling State): In this test scenario, coupling anomalies related to the charging and discharging path are simulated, such as the simultaneous existence of increased impedance of the power switching device in the discharge direction and abnormal connection of the discharge circuit.

[0087] The system was configured with a slightly high internal resistance of the discharge MOSFET and a slight loose connection in the discharge circuit. Traditional single-temperature-rise detection can only identify abnormal temperature rises, but cannot accurately pinpoint the fault type. Using the solution of this invention, the charging temperature rise of 18°C ​​is within the normal range, while the discharging temperature rise of 28°C exceeds the standard. The temperature difference between charging and discharging is 10°C, meeting the consistency anomaly condition. Furthermore, after power-off, the shunt temperature drops normally without any sustained temperature rise. Through multi-dimensional indicator decoupling, MOSFET leakage current faults and overall main circuit loose connection faults can be ruled out, accurately locating the fault as a coupling fault between the single-channel MOSFET and the discharge circuit, verifying the unique fault decoupling capability of this invention.

[0088] Please refer to Figure 3 The graph shows the temperature of the shunt under different fault conditions as a function of test time. The horizontal dashed line L0 in the graph is the 70℃ overheat protection threshold line.

[0089] The test timing is divided into four stages: 0~10s is the 400A constant current charging stage, 10~15s is the no-current (no-load) resting stage after charging, 15~25s is the 400A constant current discharging stage, and 25~35s is the no-current resting stage after discharging.

[0090] Characteristics of each curve and corresponding operating conditions: 1. Normal operating condition curve (L1) The initial temperature was 26℃. During the charging phase, the temperature rose linearly and steadily to 43℃, a charging temperature rise of 17℃. During the resting phase, the temperature dropped back to 36℃. During the discharging phase, the temperature rose steadily to 52℃, a discharging temperature rise of 16℃. After discharging, the temperature continued to decrease. The charging and discharging temperature rises were both within the acceptable range of 15~25℃, and the temperature remained below the 70℃ threshold throughout the process, with a smooth curve. Under these conditions, the temperature rise amplitude during charging and discharging met the preset temperature rise conditions, the temperature rise difference during charging and discharging met the consistency requirements, and the temperature change curve was continuous and smooth, without exceeding the preset overheating temperature threshold. Therefore, the BMS was determined to be in normal working condition.

[0091] 2. Loose connection / high internal resistance curve (L2) The temperature rise slope was significantly greater than the normal curve, and the temperature at the end of charging reached 62℃, exceeding the temperature rise standard. During the discharge stage, the temperature rose to 73℃, exceeding the 70℃ overheat protection threshold. After power failure, the cooling rate was slow. Since the temperature rise amplitude was obviously abnormal under fixed current and fixed loading time conditions, it can be judged that there is an abnormality in the main circuit of the BMS based on the temperature rise characteristic parameters.

[0092] 3. Temperature sampling failure curve (L3) In this state, although the main circuit is loaded with a charging and discharging current of 400A, the temperature change curve of the shunt obtained by the sampling remains basically horizontal, with only a small fluctuation within about 2℃, and does not reflect the temperature rise response corresponding to the actual current loading process.

[0093] Since the main circuit current is normal, but the temperature change data does not conform to the preset temperature rise change pattern, it can be determined that there is an abnormality in the temperature acquisition of the BMS.

[0094] This anomaly may be caused by a faulty temperature sensor connection, a faulty sampling line, or a faulty temperature acquisition circuit.

[0095] 4. Abnormal conduction curve of power switching device (L4) In this state, the temperature rise characteristics during the charging and discharging phases are close to normal operating conditions. However, after the current is stopped and the main circuit is disconnected, the shunt temperature does not decrease naturally but continues to rise, indicating that abnormal heat is still generated after the current is stopped. Therefore, based on the abnormal temperature recovery characteristics after the current stops, it can be determined that there is an abnormal conduction fault in the power switching device of the BMS. This abnormality may be caused by incomplete turn-off of the power switching device or abnormal leakage current.

[0096] 5. Abnormal charging / discharging temperature rise consistency curve (L5) The temperature rise during charging is within the standard range, but the temperature rise during discharging is significantly lower, with the difference between charging and discharging temperature rises exceeding the preset consistency threshold of 3°C. This indicates that the thermal response of the BMS is inconsistent under different current directions. Therefore, based on the abnormal charging and discharging temperature rise consistency characteristic parameters, it can be determined that the BMS has an abnormal charging and discharging temperature rise consistency. This abnormality may be caused by differences in the parameters of power switching devices, loop impedance, or connection status in the charging and discharging path.

[0097] By combining multiple temperature rise characteristic parameters for analysis, compared to using only a single temperature rise amplitude for judgment, this embodiment can further distinguish the state changes caused by the combined effect of different abnormal factors, thereby improving the BMS's ability to identify abnormal states.

[0098] It should be noted that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0099] Reference Figure 4 This diagram illustrates a low-voltage battery system (BMS) status diagnostic device according to an embodiment of the present invention. The BMS includes a main circuit, power switching devices disposed in the main circuit, and a shunt. The device includes: Initialization module 401 is used to place the low-voltage battery system to be tested into a preset initial state; The temperature change data acquisition module 402 is used to control the power switching device to make the main circuit generate charging current and discharging current respectively, and to acquire the temperature change data of the shunt during the current loading process and after the current stops. Temperature rise characteristic parameter calculation module 403 is used to calculate temperature rise characteristic parameters that characterize the working state of the BMS based on the temperature change data; The status monitoring module 404 is used to match the temperature change data and the temperature rise characteristic parameters with preset judgment rules, and determine the fault type or normal state corresponding to the BMS based on the matching result.

[0100] The present invention provides a low-voltage battery system BMS status diagnostic device. By using the low-voltage battery system BMS status diagnostic device, the various steps in the aforementioned low-voltage battery system BMS status diagnostic method embodiments can be implemented.

[0101] It should be noted that the module division in the various low-voltage battery system BMS status diagnostic devices provided in the above embodiments is illustrative and only represents one logical functional division. In actual implementation, other division methods may also be used. Furthermore, the functional modules in the various embodiments of this invention can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0102] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the technical solution of the embodiments of the present invention can be embodied in the form of a computer program product, which is stored in a computer storage medium and includes several instructions to cause an electronic device or processor to execute all or part of the steps of the methods in the various embodiments of the present invention. The aforementioned computer storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0103] Furthermore, the low-voltage battery system BMS status diagnosis device and the low-voltage battery system BMS status diagnosis method provided in the above embodiments belong to the same concept, and their specific implementation process can be found in the method embodiments, which will not be repeated here.

[0104] Reference Figure 5 The diagram illustrates an electronic device according to an embodiment of the present invention. Figure 5 As shown, the electronic device in this embodiment of the invention includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the above-described low-voltage battery system BMS state diagnostic method embodiment. Alternatively, when the processor executes the computer program, it implements the functions of each module in the above-described low-voltage battery system BMS state diagnostic device embodiment.

[0105] For example, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to complete this application. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which can be used to describe the execution process of the computer program in the electronic device.

[0106] The electronic device may be a desktop computer, a cloud server, or other computing device. The electronic device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that... Figure 5 This is merely one example of an electronic device and does not constitute a limitation on the electronic device. It may include more or fewer components than illustrated, or combine certain components, or different components. For example, the electronic device may also include input / output devices, network access devices, buses, etc.

[0107] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0108] The memory can be an internal storage unit of the electronic device, such as a hard drive or RAM. Alternatively, it can be an external storage device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, Flash Card, etc. Furthermore, the memory can include both internal and external storage units. The memory is used to store the computer program and other programs and data required by the electronic device. The memory can also be used to temporarily store data that has been output or will be output.

[0109] This invention also discloses a computer-readable storage medium storing a computer program that, when executed by a processor, implements the low-voltage battery system BMS state diagnosis method as described in the foregoing embodiments.

[0110] The embodiments described above are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for diagnosing the state of a low-voltage battery system's BMS, characterized in that, The BMS includes a main circuit, power switching devices disposed in the main circuit, and a shunt. The method includes: Place the low-voltage battery system to be tested into a preset initial state; By controlling the power switching device, the main circuit generates charging current and discharging current respectively, and the temperature change data of the shunt is collected during the current loading process and after the current stops. Based on the temperature change data, calculate the temperature rise characteristic parameters that characterize the working state of the BMS; The temperature change data and the temperature rise characteristic parameters are matched with preset judgment rules, and the fault type or normal state corresponding to the BMS is determined based on the matching result.

2. The method according to claim 1, characterized in that, The step of placing the low-voltage battery system to be tested into a preset initial state includes: Collect ambient temperature and the initial temperature of the shunt, and detect the static current of the BMS main circuit; When the static current is zero and the temperature difference between the initial temperature of the shunt and the ambient temperature is less than a preset temperature difference threshold, the low-voltage battery system is determined to be in the preset initial state.

3. The method according to claim 1, characterized in that, The acquisition of temperature change data of the shunt during current loading and after current cessation includes: Temperature change data of the shunt are continuously collected during the charging current and discharging current loading processes, respectively. After the charging and discharging currents stop, the temperature change data of the shunt under no current action are collected.

4. The method according to claim 3, characterized in that, The charging current and the discharging current are constant currents with equal amplitudes, and the time interval between the moment when the charging current stops and the moment when the discharging current starts to load is a preset resting time.

5. The method according to claim 1, characterized in that, The temperature rise characteristic parameters include charging temperature rise characteristic parameters, discharging temperature rise characteristic parameters, and charging / discharging temperature rise consistency characteristic parameters; The temperature rise characteristic parameters that characterize the BMS operating state based on the temperature change data include: The characteristic parameters of charging temperature rise are determined based on the temperature change data during the charging current loading process; The discharge temperature rise characteristic parameters are determined based on the temperature change data during the discharge current loading process. The charging and discharging temperature rise consistency characteristic parameter is determined based on the difference between the charging temperature rise characteristic parameter and the discharging temperature rise characteristic parameter.

6. The method according to claim 5, characterized in that, The temperature rise characteristic parameters include charging recovery temperature characteristic parameters and discharging recovery temperature characteristic parameters. The calculation of the temperature rise characteristic parameters characterizing the BMS operating state based on the temperature change data further includes: Based on the trend of the shunt temperature change over time after the charging current stops, the charging recovery characteristic parameters are determined; Based on the temperature change trend of the shunt over time after the discharge current stops, the discharge recovery characteristic parameters are determined. Both the charging recovery characteristic parameters and the discharging recovery characteristic parameters include the temperature drop rate, the temperature change trend, or the temperature change within a preset time.

7. The method according to claim 6, characterized in that, The step of determining the fault type or normal state corresponding to the BMS based on the matching result includes: When the charging temperature rise characteristic parameter or the discharging temperature rise characteristic parameter exceeds the preset temperature rise threshold, it is determined that there is a main circuit abnormality in the BMS. When the charge / discharge temperature rise consistency characteristic parameter meets the preset consistency anomaly condition, it is determined that the BMS has a charge / discharge temperature rise consistency anomaly. When the temperature recovery characteristic parameters do not meet the preset temperature recovery change law, it is determined that the BMS has an abnormal conduction fault of the power switching device. When the shape of the temperature change curve corresponding to the temperature change data is inconsistent with the preset temperature change law, and the main circuit current status is normal, it is determined that the BMS has an abnormal temperature acquisition. When multiple temperature rise characteristic parameters simultaneously meet the corresponding anomaly determination conditions, it is determined that the BMS has a coupling fault.

8. A low-voltage battery system BMS status diagnostic device, characterized in that, The BMS includes a main circuit, power switching devices disposed in the main circuit, and a shunt. The device includes: An initialization module is used to place the low-voltage battery system to be tested into a preset initial state. The temperature change data acquisition module is used to control the power switching device to generate charging current and discharging current in the main circuit, and to acquire the temperature change data of the shunt during current loading and after current stopping. The temperature rise characteristic parameter calculation module is used to calculate the temperature rise characteristic parameters that characterize the working state of the BMS based on the temperature change data. The status monitoring module is used to match the temperature change data and the temperature rise characteristic parameters with preset judgment rules, and determine the fault type or normal state corresponding to the BMS based on the matching result.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the low-voltage battery system BMS status diagnosis method as described in any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the low-voltage battery system BMS state diagnosis method as described in any one of claims 1-7.

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