Relay state diagnosis method and device and battery management system

Abstract

The invention provides a relay state diagnosis method and device and a battery management system, and relates to the technical field of relay detection, a first end of a to-be-detected relay is connected with a positive electrode end or a negative electrode end of a battery pack, and a second end of the to-be-detected relay is connected with a load side; the method comprises the steps that after it is detected that a to-be-detected relay executes an action instruction, detection voltage data of a sampling point of the to-be-detected relay are detected in real time, and the sampling point is located at the second end of the to-be-detected relay; acquiring a ratio range and a ratio change rate of the detection voltage of the second end of the relay to be detected to the voltage of the battery pack according to the detection voltage data; determining the actual state of the relay to be tested according to the ratio range and the ratio change rate; and state diagnosis is carried out on the relay to be tested according to the actual state and the action instruction, so that the state of the relay can be diagnosed timely and accurately, and misdiagnosis caused by whole vehicle interference or hardware interference can be prevented.

Description

Technical Field

[0001] This application relates to the field of relay testing technology, specifically to a relay condition diagnosis method, device, and battery management system. Background Technology

[0002] As the power source of the high-voltage system in electric vehicles, the power battery provides driving power for the entire vehicle and involves high-voltage safety and reliability. The high-voltage power-on and power-off process is controlled by various high-voltage relays, which act as high-voltage "switches". The battery's high-voltage power-on and power-off strategy relies on the voltage range of the high-voltage acquisition point to determine the actual state and faults of the relays. However, due to the influence of other hardware functions, the acquisition voltage at the relay's downstream end is prone to fluctuations, leading to misdiagnosis of relay faults. Summary of the Invention

[0003] In view of this, this application provides a relay status diagnosis method, device and battery management system, which can diagnose the relay status in a timely and accurate manner and can prevent misdiagnosis caused by vehicle interference or hardware interference itself.

[0004] To achieve the above objectives, this application provides the following technical solution: a relay state diagnosis method, wherein the first terminal of the relay under test is connected to the positive or negative terminal of a battery pack, and the second terminal of the relay under test is connected to the load side; the relay state diagnosis includes: after detecting that the relay under test executes an action command, detecting the detection voltage data of a sampling point of the relay under test in real time, wherein the sampling point is located at the second terminal of the relay under test; obtaining the ratio range and ratio change rate of the detection voltage at the second terminal of the relay under test to the battery pack voltage based on the detection voltage data; determining the actual state of the relay under test based on the ratio range and the ratio change rate; and performing state diagnosis on the relay under test based on the actual state and the action command.

[0005] In one embodiment of this application, obtaining the ratio range and ratio change rate of the detection voltage of the second terminal of the relay under test to the battery pack voltage based on the detection voltage data includes: calculating the ratio of each detection voltage to the battery pack voltage in the detection voltage data to obtain ratio data; generating a ratio change curve based on the ratio data, and determining the maximum and minimum values ​​of the ratio, and determining the ratio range based on the maximum and minimum values; and calculating the slope of the ratio change curve to obtain the ratio change rate.

[0006] In one embodiment of this application, determining the actual state of the relay under test based on the ratio range and the ratio change rate includes: determining whether the ratio range is within a first target change range and whether the ratio change rate satisfies a first target threshold range, wherein the first target change range is the possible change range of the ratio calibrated when the relay under test is closed, and the first target threshold range is the possible value range of the ratio change rate calibrated when the relay under test is closed; if the ratio range is within the first target change range and the ratio change rate satisfies the first target threshold range, then it is determined that the relay under test is actually in a closed state; otherwise, it is determined that the relay under test is actually in an open state.

[0007] In one embodiment of this application, determining the actual state of the relay under test based on the ratio range and the ratio change rate includes: determining whether the ratio range is within a second target change range and whether the ratio change rate satisfies a second target threshold range, wherein the second target change range is the possible change range of the ratio calibrated when the relay under test is disconnected, and the second target threshold range is the possible value range of the ratio change rate calibrated when the relay under test is disconnected; if the ratio range is within the second target change range and the ratio change rate satisfies the second target threshold range, then it is determined that the relay under test is actually in an open state; otherwise, it is determined that the relay under test is actually in a closed state.

[0008] In one embodiment of this application, the step of performing state diagnosis on the relay under test based on the actual state and the action command includes: if the action command is a disconnect command and the actual state is an open state, then it is determined that the relay under test has successfully disconnected; if the action command is a disconnect command and the actual state is a closed state, then it is determined that the relay under test has a sticking fault; if the action command is a close command and the actual state is an open state, then it is determined that the relay under test has an open circuit fault; if the action command is a close command and the actual state is a closed state, then it is determined that the relay under test has successfully closed.

[0009] In one embodiment of this application, the method further includes: simulating the usage environment of the relay under test to determine that the relay under test has entered the identification mode; adjusting the complex operating conditions of the relay under test after detecting that the relay under test has executed an action command; monitoring the voltage monitoring data of the sampling point of the relay under test in real time; obtaining the ratio range data and ratio change rate data of the detected voltage at the second terminal of the relay under test to the battery pack voltage based on the voltage monitoring data; calibrating a first target change range representing the possible change range of the ratio and a first target threshold range representing the possible value range of the ratio change rate when the relay under test is in the closed state from the ratio range data and the ratio change rate data; and / or calibrating a second target change range representing the possible change range of the ratio and a second target threshold range representing the possible value range of the ratio change rate when the relay under test is in the open state.

[0010] In one embodiment of this application, adjusting the complex operating conditions of the relay under test includes: randomly connecting a variable resistor and a variable capacitor to the rear end of the relay under test or to the rear end of other relays under test linked with the relay under test; and randomly turning the insulation detection function on or off.

[0011] As a second aspect of this application, this application also provides a relay state diagnostic device, wherein a first terminal of the relay under test is connected to the positive or negative terminal of a battery pack, and a second terminal of the relay under test is connected to a load side; the device includes: a real-time detection module, used to detect the detection voltage data of a sampling point of the relay under test in real time after the relay under test executes an action command, the sampling point being located at the second terminal of the relay under test; a data processing module, used to obtain the ratio range and ratio change rate of the detection voltage at the second terminal of the relay under test to the battery pack voltage based on the detection voltage data; a state determination module, used to determine the actual state of the relay under test based on the ratio range and the ratio change rate; and a state diagnostic module, used to perform state diagnostics on the relay under test based on the actual state and the action command.

[0012] As a third aspect of this application, embodiments of this application also provide a battery management system, including: a memory for storing an executable computer program; and a processor for calling and running the executable computer program from the memory, causing the processor to perform the aforementioned method.

[0013] As a fourth aspect of this application, embodiments of this application also provide a computer-readable storage medium storing a computer program that, when executed, implements the aforementioned method.

[0014] The relay status diagnosis method provided in this application determines the actual status of the relay by obtaining the ratio range and rate of change of the detected voltage to the battery pack voltage at the sampling point after the execution of the relay's action command. Based on the actual status and the action command, the relay is diagnosed. Since the ratio range and rate of change of the detected voltage to the battery pack voltage at the relay's rear end are less affected by the load capacitance of different hardware or other components, the relay status can be diagnosed in a timely and accurate manner, preventing misdiagnosis caused by vehicle interference or hardware interference itself. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, 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 embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic flowchart illustrating the state diagnosis of a relay as provided in an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of a relay network provided for an embodiment of this application.

[0018] Figure 3 This is a schematic diagram of the state calibration process of the relay under test provided in an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of the state diagnosis process of the relay under test provided in the embodiments of this application.

[0020] Figure 5 The diagram shown is a structural schematic of a relay status diagnosis device provided in an embodiment of this application.

[0021] Figure 6 The diagram shown is a structural schematic of a battery management system provided in an embodiment of this application. Detailed Implementation

[0022] This application provides a relay status diagnosis method, device, and battery management system. By real-time detection of the detection voltage data at the sampling point located at the second end of the relay under test, the range and rate of change of the ratio between the detection voltage at the second end of the relay under test and the battery pack voltage are obtained, thereby determining the actual status of the relay under test. Based on the actual status and action command, the status diagnosis of the relay under test is performed, which can diagnose the relay status in a timely and accurate manner, preventing misdiagnosis caused by vehicle interference or hardware interference itself.

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] In related technologies, the power battery, as the power source of the high-voltage system of an electric vehicle, provides driving power for the entire vehicle and involves high-voltage safety and reliability. The high-voltage power-on and power-off process is controlled by various high-voltage relays, which act as high-voltage "switches". The battery's high-voltage power-on and power-off strategy relies on the voltage value range of the high-voltage acquisition points to determine the actual state and faults of the relays. High-voltage control systems often involve multiple different high-voltage acquisition points: when using high-voltage acquisition points to determine the actual state and faults of relays, it depends on the voltage value range of the corresponding high-voltage acquisition points under different control commands.

[0025] Current control strategies for acquiring and diagnosing voltage thresholds for relay status are largely based on fixed data provided by the hardware design. However, during actual vehicle testing, the voltage across the relay can fluctuate due to factors such as the load capacitance of the charger or other components, or the influence of other hardware functions (e.g., insulation detection). This can lead to misdiagnosis of relay faults, requiring manual calibration of different relay diagnostic thresholds for different batches of vehicles. This calibration process is inefficient, and even within the same batch, the complexity of vehicle operating conditions can cause variations in voltage ranges. In short, relying on a fixed voltage range can result in incorrect relay fault diagnoses.

[0026] The existing strategy fails to connect other loads for testing beforehand, does not cover the complex operating conditions of the entire vehicle, assumes that other components and functions have no impact on battery controller voltage acquisition, and directly fixes the voltage threshold range for diagnosis. The testing environment is too ideal, and the strategy has limited coverage. If the calibration data verified on the bench is directly used for the entire vehicle, it will cause incorrect diagnosis of the vehicle's relay status. In practice, it is necessary to adaptively update the strategy or change the threshold range for different vehicle environments and operating conditions.

[0027] To address the issue of false alarms due to relay faults in scenarios involving hardware circuit changes, complex vehicle operating conditions, and voltage fluctuations in hardware acquisition, this application provides a relay status diagnosis method. The first terminal of the relay under test is connected to either the positive or negative terminal of the battery pack, and the second terminal of the relay under test is connected to the load side. Figure 1The diagram shown is a flowchart illustrating a relay status diagnosis method provided in an embodiment of this application, applied to the controller of a battery management system (BMS). Figure 1 As shown, the relay status diagnosis method includes: Step S11: After the relay under test executes the action command, the detection voltage data of the sampling point of the relay under test is detected in real time. The sampling point is located at the second end of the relay under test.

[0028] The power battery, as the power source of the high-voltage system in an electric vehicle, provides driving power to the entire vehicle and relies on various high-voltage relays for high-voltage power-on and power-off control. See [link to relay network diagram for electric vehicle high-voltage system]. Figure 2 The relay network includes: a main positive relay, a main negative relay, a pre-charge relay, a fast-charge positive relay, a fast-charge negative relay, a slow-charge positive relay, a heating positive relay, and a heating negative relay. The positive terminal of the battery pack is connected to the heating positive relay. The positive terminal of the battery pack is also connected to the main positive relay, the slow-charge positive relay, and the fast-charge positive relay via a current sensor. The pre-charge resistor is connected in series with the pre-charge relay and then in parallel across the main positive relay. The negative terminal of the battery pack is connected to the fast-charge negative relay, the main negative relay, and the heating negative relay. A fast-charge input load is connected between the fast-charge positive relay and the fast-charge negative relay; a slow-charge input load is connected between the slow-charge positive relay and the main negative relay; a high-voltage input load is connected between the main positive relay and the main negative relay; and a heating output load is connected between the heating positive relay and the heating negative relay.

[0029] The relay under test can be any relay in the relay network described above, with the corresponding sampling point located at the second end of the relay, i.e., the side of the relay furthest from the battery pack. For example, the heating positive voltage sampling point is located at the rear end of the heating positive relay, i.e., the side furthest from the battery pack. The total positive voltage sampling point is located at the rear end of the total positive relay and the pre-charge relay; the slow charging positive voltage sampling point is located at the rear end of the slow charging positive relay; the fast charging positive voltage sampling point is located at the rear end of the fast charging positive relay; the fast charging negative voltage sampling point is located at the rear end of the fast charging negative relay; the total negative voltage sampling point is located at the rear end of the total negative relay; and the heating negative voltage sampling point is located at the rear end of the heating negative relay.

[0030] After successful parameter identification of the relay under test (DUT), the DUT is connected to the vehicle's operating conditions, and diagnostic mode is entered to diagnose the relay's status. In diagnostic mode, relevant detection circuits and controllers can be used to monitor the voltage at the sampling point at the second terminal of the DUT in real time. The specific voltage detection method is not limited. The DUT executes an action command, which can be either an open or closed command. This involves determining whether the relay command has switched, including whether the previous command was open and the current command is closed, or vice versa. After detecting the DUT's action command, the voltage data at the sampling point of the DUT is monitored in real time. Specifically, the voltage data obtained after the DUT has executed the action command and stabilized for a certain period can be selected from the real-time voltage data. This time period can be set as needed and is not specifically limited here.

[0031] Step S12: Obtain the range and rate of change of the ratio between the detected voltage at the second terminal of the relay under test and the battery pack voltage based on the detected voltage data.

[0032] The battery pack voltage is the voltage of the battery pack connected to the first terminal of the relay under test. It can be obtained through communication with the battery pack or through direct measurement; there is no restriction on this. The detected voltage data includes multiple detected voltages, and the ratio of each detected voltage to the battery pack voltage can be calculated to obtain the range and rate of change of the ratio between the detected voltage and the battery pack voltage.

[0033] Step S13: Determine the actual state of the relay under test based on the ratio range and the ratio change rate.

[0034] In this embodiment, target ranges corresponding to the ratio range and the ratio change rate are pre-calibrated. It is then determined whether the ratio range and the ratio change rate are within their respective target ranges, thereby determining the actual state of the relay under test. The actual state of the relay under test can be either in an open state or in a closed state.

[0035] Step S14: Perform a status diagnosis on the relay under test based on the actual status and the action command.

[0036] Determine whether the actual state of the relay under test matches the target state after the action command is executed. If they match, the relay under test is operating normally. If they do not match, the relay under test is not operating normally, i.e., the relay under test has a sticking or open circuit fault.

[0037] The relay status diagnosis method of this application determines the actual status of the relay by obtaining the range and rate of change of the ratio between the detected voltage and the battery pack voltage at the sampling point after the execution of the action command of the relay under test. Based on the actual status and the action command, the relay under test is diagnosed. Since the range and rate of change of the ratio between the detected voltage and the battery pack voltage at the relay's rear end are less affected by the load capacitance of different hardware or other components, the relay status can be diagnosed in a timely and accurate manner, preventing misdiagnosis caused by vehicle interference or hardware interference itself.

[0038] To more clearly illustrate the technical solutions provided in the embodiments of this application, the following further describes a relay state diagnosis method provided in this application.

[0039] In this embodiment of the application, before performing state diagnosis on the relay under test, it is necessary to pre-calibrate the ratio range and the rate of change of the ratio between the detection voltage at the second terminal of the relay and the battery pack voltage, so as to determine the target range of the possible range of the ratio and the target threshold range of the possible range of the rate of change of the ratio. The target range of the ratio and the target threshold range can be the corresponding ranges when the relay under test is in a closed state or an open state, so that the actual state of the relay under test can be determined based on the obtained ratio range and the rate of change of the ratio during subsequent state diagnosis.

[0040] Based on this, in this embodiment of the application, optionally, the method further includes: simulating the usage environment of the relay under test to determine that the relay under test has entered the identification mode; adjusting the complex operating conditions of the relay under test after detecting that the relay under test has executed an action command; monitoring the voltage monitoring data of the sampling point of the relay under test in real time; obtaining the ratio range data and ratio change rate data of the detected voltage at the second terminal of the relay under test to the battery pack voltage based on the voltage monitoring data; calibrating, from the ratio range data and the ratio change rate data, a first target change range representing the possible change range of the ratio and a first target threshold range representing the possible value range of the ratio change rate when the relay under test is in the closed state, and / or calibrating, a second target change range representing the possible change range of the ratio and a second target threshold range representing the possible value range of the ratio change rate when the relay under test is in the open state.

[0041] In this embodiment, the relay under test (DUT) and the BMS controller are first connected to a test bench, and the DUT enters recognition mode. The test bench simulates various complex operating conditions in advance, such as charger output circuit detection, rapid discharge at the load end, and insulation detection, using simulated power supplies, variable resistors, and variable capacitors, covering a full range of vehicle operating conditions. The BMS controller software can be configured with a recognition calibration switch. If calibration of the current relay is required, the recognition calibration switch is turned on; otherwise, it is turned off. It should be noted that this embodiment does not require calibration of every DUT; only relays of the same type need to be calibrated, such as the same model, or relays of different models but with essentially the same parameters. This way, even if a relay of the same model or other similar hardware is subsequently replaced, recalibration of the DUT is not required.

[0042] During calibration, after detecting the execution of an action command by the relay under test (DUT), the complex operating conditions of the DUT can be adjusted. This includes, but is not limited to: randomly connecting variable resistors and variable capacitors to the downstream end of the DUT or other relays linked to it; randomly enabling or disabling the insulation detection function. Different battery pack voltages can also be simulated using a simulated power supply. The simulated power supply can simulate different voltage platforms, and each DUT needs to be linked with other relays to collect voltage changes, with different resistors or capacitors connected to the downstream load to simulate voltage changes under various operating conditions. During this adjustment process, the voltage monitoring data at the sampling points of the DUT is monitored in real time. This voltage monitoring data can be the voltage data at the sampling points before and after the DUT's action, including the voltage data after the DUT has been in operation for a period of time, i.e., the voltage data that tends to stabilize after the DUT's action. Based on the voltage monitoring data, the ratio range data and the ratio change rate data of the detected voltage at the second terminal of the DUT to the battery pack voltage are obtained. Based on the ratio range data and the ratio change rate data, the possible range of change of the ratio and the possible value range of the ratio change rate can be determined, thereby completing the calibration of the target change range and the target threshold range. Since the action command may be a closing command or an opening command, the calibrated target variation range can be either a first target variation range of the possible variation range of the characteristic ratio of the relay under test in the closed state, or a second target variation range of the possible variation range of the characteristic ratio of the relay under test in the open state. Similarly, the calibrated target threshold range can be either a first target threshold range of the possible values ​​of the characteristic ratio change rate of the relay under test in the closed state, or a second target threshold range of the possible values ​​of the characteristic ratio change rate of the relay under test in the open state. The calibrated target variation range and target threshold range are stored in the electrically erasable programmable read-only memory (EEPROM) of the BMS controller for state diagnosis of the relay under test.

[0043] This application embodiment identifies the voltage changes of the relay under test before and after its operation under various operating conditions. Finally, for all the test data of the relay under test, the corresponding diagnostic thresholds are stored. The diagnostic thresholds include the aforementioned target change range and target threshold range, which can accurately define the diagnostic thresholds of the relay under test, facilitating subsequent state diagnosis of the relay under test.

[0044] The following explanation uses the first target range of the possible range of the characteristic ratio and the first target threshold range of the possible range of the characteristic ratio change rate when the relay under test is in the closed state as an example. Figure 3 As shown, the state calibration process for the relay under test includes: Step 100: Connect to the test bench.

[0045] Connect the relay under test and the BMS controller to the test bench, which can only simulate the full-scenario vehicle operating conditions.

[0046] Step 101: The relay enters the identification mode.

[0047] The BMS controller software can be configured with an identification calibration switch. If it is necessary to calibrate the current relay, turn on the identification calibration switch.

[0048] Step 102: Determine if a closure instruction has been issued. If yes, proceed to step 103; otherwise, jump to step 106.

[0049] Does the BMS controller issue a closing command to the relay? If yes (Y in the figure), the relay executes the closing command. If no (N in the figure), proceed to step 106 for judgment.

[0050] Step 103: Connect a variable resistor, variable capacitor, or insulation.

[0051] To simulate full-scale vehicle operating conditions, variable resistors and variable capacitors can be randomly connected to the downstream end of the relay under test or other relays linked to it. Insulation detection functions can also be randomly enabled or disabled. Different battery pack voltages can also be simulated using a simulated power supply.

[0052] Step 104: Monitor the voltage acquisition value changes in real time after the relay is closed.

[0053] The BMS controller monitors the voltage monitoring data of the corresponding sampling point after the relay is closed in real time. The voltage monitoring data includes the voltage acquisition values ​​at different times.

[0054] Step 105: Calculate the range of the ratio between the collected voltage value and the battery voltage value after the relay is closed, as well as the rate of change of the ratio.

[0055] Based on the collected voltage values, the ratio of each voltage value to the battery voltage value is calculated, and then the range of the ratio and the rate of change of the ratio are determined.

[0056] Step 106: Determine if a disconnect command has been issued. If yes, proceed to step 107; otherwise, return to step 102.

[0057] Determine if the BMS controller has issued a disconnect command to the relay. If so (Y in the figure), the relay executes the disconnect command. Otherwise, return to step 102.

[0058] Step 107: Connect a variable resistor, variable capacitor, or insulation.

[0059] Step 108: Monitor the voltage acquisition value changes in real time after the relay is closed.

[0060] Step 109: Calculate the range of the ratio between the collected voltage value and the battery voltage value after the relay is closed, as well as the rate of change of the ratio.

[0061] The methods for steps 107 to 109 are the same as those for steps 103 to 105, and will not be repeated here.

[0062] Step 110: Filter out the ratio range and ratio change rate of the relay closure and in EE.

[0063] The system filters out the range of ratios that indicate relay closure from all acquired ratio ranges, and filters out the ratio change rate that indicates relay closure from all acquired ratio change rates. The filtered ratio ranges and ratio change rates are then stored in an electrically erasable programmable read-only memory (EEPROM) (EE).

[0064] In other embodiments of this application, the range of ratios in which the relay is disconnected can be selected from all the obtained ratio ranges, and the rate of change of the ratio in which the relay is disconnected can be selected from all the obtained ratio change rates.

[0065] Step 111: Recognition successful.

[0066] This completes the calibration of the relay's ratio range and ratio change rate.

[0067] This application embodiment does not require on-site testing of the entire vehicle, nor does it require obtaining component information of each vehicle in advance. On the test bench, various complex operating conditions such as charger output circuit detection, whether there is rapid discharge at the load end, and insulation detection process are simulated in advance by simulating power supply, variable resistor and variable capacitor. It can cover the simulation of the entire vehicle operating conditions, identify specific voltage curves in advance, and adaptively adjust the corresponding relay diagnostic strategies and thresholds during the later vehicle operation, so as to diagnose the fault status of each relay in a timely and accurate manner.

[0068] If the relay under test is a positive relay, such as a main positive relay, pre-charge relay, fast-charge positive relay, slow-charge positive relay, or heating positive relay, the relay status is diagnosed by testing the voltage change during the relay's operation (0V or close to the battery pack voltage). 0V indicates open, otherwise, close to the battery pack voltage indicates closed. However, in reality, during rapid power-on and power-off, the load motor at the main drive end does not have a rapid discharge function, and the voltage at the main drive's rear end will be close to the battery pack voltage. In this case, it is easy to falsely report a main positive relay sticking fault. If the relay under test is a negative relay, such as a main negative relay, fast-charge negative relay, or heating negative relay, the relay status is diagnosed by testing the voltage change during the relay's operation (0mV-5000mV). A value greater than 3300mV (which can be calibrated according to the hardware design) indicates open, otherwise, a value less than 3300mV indicates closed. However, in reality, during the initial interaction between the battery and the charger during battery charging, before the battery-side relay closes, the charger detects the output circuit and executes the closing and then opening of the charger-side relay. This results in a negative voltage being collected at the negative terminal of the battery charging circuit, which can lead to a false alarm of a stuck battery charging negative relay. In non-heating conditions, with the heating relay not closed, the voltage at the rear of the heating negative relay fluctuates periodically between 0mV and 5000mV due to the operation of the insulation detection circuit relay, which can also lead to a false alarm of a stuck heating negative relay.

[0069] It is evident that directly determining the relay's state based on threshold judgments using the collected voltage is prone to false alarms. This embodiment of the application obtains the range and rate of change of the ratio between the detected voltage at the second terminal of the relay under test and the battery pack voltage based on the detected voltage data, thereby determining the relay's state. Optionally, the ratio of each detected voltage to the battery pack voltage in the detected voltage data is calculated to obtain ratio data; a ratio change curve is generated based on the ratio data, and the maximum and minimum values ​​of the ratios are determined; the ratio range is determined based on the maximum and minimum values; the slope of the ratio change curve is calculated to obtain the rate of change of the ratio. After calculating the ratio of each detected voltage to the battery pack voltage in the detected voltage data, the maximum and minimum values ​​of the ratios can be directly determined, or a ratio change curve showing the ratio changing over time can be generated based on the relationship between each ratio and time, and the maximum and minimum values ​​of the ratios can be determined based on this ratio change curve. The ratio range is the numerical interval formed by the maximum and minimum values. The slope of each point on the ratio change curve is also calculated; this slope is the rate of change of the ratio, and the range of values ​​for the rate of change of the ratio can be determined. This allows for the accurate acquisition of the ratio range and rate of change of the detection voltage at the second terminal of the relay under test to the battery pack voltage. Subsequently, the actual state of the relay under test can be accurately determined based on this ratio range and rate of change.

[0070] After obtaining the ratio range and rate of change of the detected voltage at the second terminal of the relay under test (TUT) to the battery pack voltage, it is necessary to further determine the actual state of the TUT for subsequent state diagnosis. Specifically, the ratio range can be compared with a target range of change, and the rate of change of the ratio can be compared with a corresponding target threshold range. The actual state of the TUT is determined based on the comparison results. Considering that the target range of change and the target threshold range can be the first target range of change and the first target threshold range when the TUT is in a closed state, it is optional to determine whether the ratio range is within the first target range of change and whether the rate of change of the ratio meets the first target threshold range. Here, the first target range of change is the possible range of change of the ratio calibrated when the TUT is closed, and the first target threshold range is the possible range of values ​​for the rate of change of the ratio calibrated when the TUT is closed. If the ratio range is within the first target range of change and the rate of change of the ratio meets the first target threshold range, it is determined that the TUT is actually in a closed state; otherwise, it is determined that the TUT is actually in an open state. By comparing the obtained ratio range and ratio change rate with the first target change range and first target threshold range when the relay under test is in the closed state, respectively, if both are within the corresponding diagnostic threshold range, it indicates that the relay under test is currently in the closed state. If the ratio range exceeds the corresponding first target change range, or the ratio change rate exceeds the corresponding first target threshold range, it is determined that the relay under test is currently in the open state, thus accurately determining the actual state of the relay under test.

[0071] The target change range and target threshold range can also be a second target change range and a second target threshold range when the relay under test is in an open state. Optionally, it is determined whether the ratio range is within the second target change range and whether the ratio change rate meets the second target threshold range, wherein the second target change range is the possible change range of the ratio calibrated when the relay under test is open, and the second target threshold range is the possible value range of the ratio change rate calibrated when the relay under test is open; if the ratio range is within the second target change range and the ratio change rate meets the second target threshold range, then it is determined that the relay under test is actually in an open state; otherwise, it is determined that the relay under test is actually in a closed state. By comparing the obtained ratio range and ratio change rate with the second target change range and the second target threshold range when the relay under test is in an open state, if both are within the corresponding diagnostic threshold range, it indicates that the relay under test is currently in an open state. If the ratio range exceeds the corresponding second target change range, or the ratio change rate exceeds the corresponding second target threshold range, then it is determined that the relay under test is currently in a closed state, which can also accurately determine the actual state of the relay under test.

[0072] After determining the actual state of the relay under test, if the actual state of the relay under test is the same as the state required by the executed action command, it indicates that the command was executed successfully and the relay under test is normal. If the actual state of the relay under test is different from the state required by the executed action command, it indicates that the command execution failed and the relay under test has an abnormal fault. Based on this, in this embodiment, optionally, if the action command is a disconnect command and the actual state is disconnected, it is determined that the relay under test has successfully disconnected; if the action command is a disconnect command and the actual state is closed, it is determined that the relay under test has a sticking fault; if the action command is a close command and the actual state is disconnected, it is determined that the relay under test has an open circuit fault; if the action command is a close command and the actual state is closed, it is determined that the relay under test has successfully closed.

[0073] If the action command is a disconnect command, the target state of the relay under test should be disconnected after the relay executes the disconnect command. If the actual detected state is disconnected, it means that the actual state of the relay under test matches the target state of the action command, and the relay under test has successfully disconnected. If the actual detected state is closed, it means that the actual state of the relay under test does not match the target state of the action command, and the relay under test has failed to disconnect, indicating that the relay under test has a sticking fault.

[0074] If the action command is a closing command, the target state of the relay under test should be closed after executing the closing command. If the actual detected state is open, it means that the actual state of the relay under test is inconsistent with the target state of the action command, the relay under test has failed to close, and there is an open circuit fault in the relay under test. If the actual detected state is closed, it means that the actual state of the relay under test is consistent with the target state of the action command, the relay under test has closed successfully, and the relay under test is normal and without fault.

[0075] This application embodiment can accurately determine whether the state of the relay under test is normal and whether there is a sticking or open circuit fault by judging whether the actual state of the relay under test is consistent with the target state required by the action command.

[0076] The following explanation uses the first target variation range and the first target threshold range when the relay under test is in the closed state as examples to illustrate the diagnostic thresholds. Figure 4 As shown, the state diagnosis process for the relay under test includes: Step 200: Access vehicle operating conditions.

[0077] Connect the relay under test and the BMS controller to the vehicle operating conditions.

[0078] Step 201: The relay enters diagnostic mode.

[0079] The BMS controller software can be configured with an identification calibration switch, which is turned off when performing status diagnostics on the current relay.

[0080] Step 202: Determine if a closure instruction has been issued. If yes, proceed to step 203; otherwise, jump to step 208.

[0081] Where Y represents yes and N represents no. Does the BMS controller issue a closing command to the relay? If yes, the relay executes the closing command. If no, proceed to step 208 for judgment.

[0082] Step 203: Monitor the voltage acquisition value changes in real time after the relay is closed.

[0083] Step 204: Calculate the range of the ratio between the collected voltage value and the battery voltage value after the relay is closed, as well as the rate of change of the ratio.

[0084] The methods in steps 203 and 204 are respectively the same as Figure 3 The methods for steps 104 and 105 are the same, and will not be repeated here.

[0085] Step 205: Determine whether the calculated ratio range and the ratio change rate are within the threshold range of the closed relay. If yes, proceed to step 207; otherwise, jump to step 206.

[0086] Determine whether the ratio range is within the range of the first target change, and whether the ratio change rate is within the range of the first target threshold.

[0087] Step 206: Relay closure failed, reporting a relay open circuit fault.

[0088] If the ratio is not within the range of the first target change, or the ratio change rate is not within the range of the first target threshold, it indicates that the actual state of the relay under test is inconsistent with the target state of the closing command, the relay closing fails, and an open circuit fault is reported.

[0089] Step 207: The relay closed successfully.

[0090] If the ratio is within the range of the first target change and the rate of change of the ratio is within the range of the first target threshold, it means that the actual state of the relay under test is consistent with the target state of the closing command, the relay is successfully closed, and the relay is normal.

[0091] Step 208: Determine if a disconnect command has been issued. If yes, proceed to step 209; otherwise, return to step 202.

[0092] Does the BMS controller issue a disconnect command to the relay? If so, the relay executes the disconnect command. Otherwise, return to step 202.

[0093] Step 209: Monitor the voltage acquisition value changes in real time after the relay is closed.

[0094] Step 210: Calculate the range of the ratio between the collected voltage value and the battery voltage value after the relay is closed, as well as the rate of change of the ratio.

[0095] Step 211: Determine whether the calculated ratio range and the ratio change rate are within the threshold range of the closed relay. If yes, proceed to step 212; otherwise, jump to step 213.

[0096] The methods for steps 209 to 211 are the same as those for steps 203 to 205, and will not be repeated here.

[0097] Step 212: Relay disconnection failed, reporting a relay sticking fault.

[0098] If the ratio is within the range of the first target change and the rate of change of the ratio is within the range of the first target threshold, it indicates that the actual state of the relay under test is inconsistent with the target state of the disconnection command, the relay disconnection fails, and a relay sticking fault is reported.

[0099] Step 213: The relay was successfully disconnected.

[0100] If the ratio is not within the range of the first target change, or the ratio change rate is not within the range of the first target threshold, it means that the actual state of the relay under test is consistent with the target state of the disconnection command, the relay is successfully disconnected, and the relay is normal.

[0101] The relay status diagnosis method of this application addresses the problems of low efficiency in manual calibration and false alarms of relay faults in scenarios involving hardware circuit changes, complex vehicle operating conditions, and voltage fluctuations in hardware acquisition. In recognition mode, the method detects the voltage changes after successful closure of different relays in real time, calculates the ratio of this voltage change to the battery pack voltage, and stores the closure diagnosis thresholds (including the ratio range and the ratio change rate) of each relay in the EEPROM memory of the BMS controller. A software-configured recognition calibration switch is used; if the vehicle hardware is replaced, this switch can be turned on, requiring re-identification of the corresponding diagnostic thresholds on a test bench. After successful identification, the data is then sent to the vehicle. In diagnostic mode, the voltage change during the current relay operation is acquired, and the ratio of this voltage change to the battery pack voltage is calculated. The diagnostic thresholds (ratio range and ratio change rate) of each relay identified in the EEPROM memory of the BMS controller are retrieved for comparison. Only when both the ratio range and the ratio change rate are met can the relay be judged to have closed successfully. Otherwise, if the ratio range or the ratio change rate does not meet the requirements, it indicates that the relay has not closed successfully. The fault status of the relay can be diagnosed in real time, thereby protecting the high-voltage circuit in a timely manner.

[0102] Compared to simple diagnosis with a fixed voltage threshold range, the relay status diagnosis method of this application embodiment does not require on-site calibration data for different vehicles and different operating conditions. Using the same version of software, through the threshold range identified on the test bench and the adaptive diagnostic threshold range of the vehicle, the relay status can be diagnosed in a timely manner, and the misdiagnosis of relay faults caused by vehicle interference or hardware interference itself can be prevented.

[0103] In one exemplary embodiment of this specification, a relay condition diagnostic device is also provided, applied to the controller of a power battery management system. The first terminal of the relay under test is connected to the positive or negative terminal of the battery pack, and the second terminal of the relay under test is connected to the load side. Figure 5 As shown, the relay status diagnostic device 500 includes: The real-time detection module 501 is used to detect the detection voltage data of the sampling point of the relay under test in real time after the relay under test executes the action command. The sampling point is located at the second end of the relay under test. The data processing module 502 is used to obtain the range and rate of change of the ratio between the detected voltage at the second terminal of the relay under test and the battery pack voltage based on the detected voltage data. The state determination module 503 is used to determine the actual state of the relay under test based on the ratio range and the ratio change rate. The status diagnosis module 504 is used to perform status diagnosis on the relay under test based on the actual status and the action command.

[0104] In one specific embodiment, the data processing module 502 is used to: calculate the ratio of each of the detected voltages to the battery pack voltage in the detected voltage data to obtain ratio data; generate a ratio change curve based on the ratio data, and determine the maximum and minimum values ​​of the ratio, and determine the ratio range based on the maximum and minimum values; calculate the slope of the ratio change curve to obtain the ratio change rate.

[0105] In one specific implementation, the state determination module 503 is used to: determine whether the ratio range is within a first target change range and whether the ratio change rate satisfies a first target threshold range, wherein the first target change range is the possible change range of the ratio calibrated when the relay under test is closed, and the first target threshold range is the possible value range of the ratio change rate calibrated when the relay under test is closed; if the ratio range is within the first target change range and the ratio change rate satisfies the first target threshold range, then it is determined that the relay under test is actually in a closed state; otherwise, it is determined that the relay under test is actually in an open state.

[0106] In one specific embodiment, the state determination module 503 is used to: determine whether the ratio range is within the second target change range and whether the ratio change rate meets the second target threshold range, wherein the second target change range is the possible change range of the ratio calibrated when the relay under test is disconnected, and the second target threshold range is the possible value range of the ratio change rate calibrated when the relay under test is disconnected; if the ratio range is within the second target change range and the ratio change rate meets the second target threshold range, then it is determined that the relay under test is actually in the disconnected state; otherwise, it is determined that the relay under test is actually in the closed state.

[0107] In one specific implementation, the state diagnosis module 504 is used to: determine that the relay under test has successfully disconnected if the action command is a disconnect command and the actual state is a disconnected state; determine that the relay under test has a sticking fault if the action command is a disconnect command and the actual state is a closed state; determine that the relay under test has an open circuit fault if the action command is a closed command and the actual state is a disconnected state; and determine that the relay under test has successfully closed if the action command is a closed command and the actual state is a closed state.

[0108] In one specific embodiment, the device further includes a calibration module, configured to: simulate the operating environment of the relay under test and determine that the relay under test has entered the identification mode; adjust the complex operating conditions of the relay under test after detecting that the relay under test has executed an action command; monitor the voltage monitoring data of the sampling point of the relay under test in real time; obtain the ratio range data and ratio change rate data of the detected voltage at the second terminal of the relay under test to the battery pack voltage based on the voltage monitoring data; calibrate, from the ratio range data and the ratio change rate data, a first target range of possible changes in the ratio and a first target threshold range of possible values ​​of the ratio change rate when the relay under test is in the closed state, and / or, calibrate a second target range of possible changes in the ratio and a second target threshold range of possible values ​​of the ratio change rate when the relay under test is in the open state.

[0109] In one specific implementation, the calibration module is also used to: randomly connect a variable resistor and a variable capacitor to the rear end of the relay under test or to the rear end of other relays under test that are linked to the relay under test; and randomly enable or disable the insulation detection function.

[0110] Specific limitations regarding the relay condition diagnostic device can be found in the limitations of the relay condition diagnostic method described above, and will not be repeated here. Each module in the aforementioned relay condition diagnostic device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in a computer device, or stored in software in the memory of a computer device, so that the processor can call and execute the corresponding operations of each module.

[0111] Regarding the apparatus in the above embodiments, the specific manner in which each unit performs its operation has been described in detail in the embodiments concerning the relay state diagnosis method, and will not be elaborated upon here.

[0112] Figure 6 This is a schematic diagram of a battery management system provided in an embodiment of this application.

[0113] For example, such as Figure 6 As shown, the battery management system includes a memory 601 and a processor 602. The memory 601 stores an executable computer program 6011, and the processor 602 is used to call and execute the executable computer program 6011 to perform a relay status diagnosis method.

[0114] This embodiment can divide the battery management system into functional modules according to the above method embodiment. For example, each module can correspond to a separate function module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0115] When each functional module is divided according to its corresponding function, the battery management system may include: a real-time detection module, a data processing module, a status determination module, and a status diagnosis module, etc.

[0116] It should be noted that all relevant content of each step involved in the above method embodiments can be referenced from the functional description of the corresponding functional module, and will not be repeated here.

[0117] The battery management system provided in this embodiment is used to execute the above-described relay status diagnosis method, and thus can achieve the same effect as the above implementation method.

[0118] When using integrated units, the battery management system may include a processing module and a storage module. The processing module is used to control and manage the operations of the battery management system. The storage module supports the processing module in executing computer programs and processing data.

[0119] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits as disclosed in this application. The processor may also be a combination of computing functions, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and microprocessors, etc., and the storage module may be a memory.

[0120] This embodiment also provides a computer-readable storage medium (including but not limited to disk storage, CD-ROM, optical storage, etc.) storing computer program code. When the computer program code is run on a computer, the computer executes the above-mentioned related method steps to implement the relay status diagnosis method provided in the above embodiment. The computer-readable storage medium may include, but is not limited to, any type of disk, including floppy disks, optical disks, Digital Video Discs (DVDs), Compact Disc Read-Only Memory (CD-ROMs), microdrives, and magneto-optical disks, read-only memory (ROMs), random access memory (RAMs), erasable programmable read-only memory (EPROMs), electrically erasable programmable read-only memory (EEPROMs), dynamic random access memory (DRAMs), video random access memory (VRAMs), flash memory devices, magnetic cards or optical cards, nanosystems (including molecular memory ICs), or any type of medium or device suitable for storing instructions and / or data.

[0121] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned related steps to implement a relay status diagnosis method provided in the above embodiment.

[0122] The beneficial effects of the above embodiments can be referred to the beneficial effects of the corresponding methods provided above, and will not be repeated here.

[0123] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0124] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0125] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0126] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0127] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0128] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for diagnosing the condition of a relay, characterized in that, The first terminal of the relay under test is connected to either the positive or negative terminal of the battery pack, and the second terminal of the relay under test is connected to the load side; the method includes: After the relay under test is detected to execute an action command, the detection voltage data of the sampling point of the relay under test is detected in real time, and the sampling point is located at the second end of the relay under test; Based on the detected voltage data, obtain the range and rate of change of the ratio between the detected voltage at the second terminal of the relay under test and the battery pack voltage; The actual state of the relay under test is determined based on the ratio range and the ratio change rate. The status of the relay under test is diagnosed based on the actual status and the action command.

2. The method according to claim 1, characterized in that, The step of obtaining the range and rate of change of the ratio between the detected voltage at the second terminal of the relay under test and the battery pack voltage based on the detected voltage data includes: Calculate the ratio of each detected voltage to the battery pack voltage in the detected voltage data to obtain the ratio data; A ratio change curve is generated based on the ratio data, and the maximum and minimum values ​​of the ratio are determined. The range of the ratio is then determined based on the maximum and minimum values. Calculate the slope of the ratio change curve to obtain the ratio change rate.

3. The method according to claim 1, characterized in that, Determining the actual state of the relay under test based on the ratio range and the ratio change rate includes: Determine whether the range of the ratio is within the first target change range and whether the ratio change rate meets the first target threshold range, wherein the first target change range is the possible change range of the ratio calibrated when the relay under test is closed, and the first target threshold range is the possible value range of the ratio change rate calibrated when the relay under test is closed; If the ratio is within the range of the first target change and the rate of change of the ratio meets the range of the first target threshold, then it is determined that the relay under test is actually in a closed state. Otherwise, it is determined that the relay under test is actually in the open state.

4. The method according to claim 1, characterized in that, Determining the actual state of the relay under test based on the ratio range and the ratio change rate includes: Determine whether the ratio range is within the second target change range and whether the ratio change rate meets the second target threshold range, wherein the second target change range is the possible change range of the ratio calibrated when the relay under test is disconnected, and the second target threshold range is the possible value range of the ratio change rate calibrated when the relay under test is disconnected; If the ratio is within the range of the second target change and the rate of change of the ratio meets the range of the second target threshold, then it is determined that the relay under test is actually in the open state. Otherwise, it is determined that the relay under test is actually in a closed state.

5. The method according to claim 1, characterized in that, The step of performing state diagnosis on the relay under test based on the actual state and the action command includes: If the action command is a disconnect command and the actual state is a disconnect state, then it is determined that the relay under test has successfully disconnected. If the action command is a disconnect command and the actual state is a closed state, then it is determined that the relay under test has a sticking fault. If the action command is a closing command and the actual state is an open state, then it is determined that the relay under test has an open circuit fault. If the action command is a closing command and the actual state is a closed state, then the relay under test is determined to have closed successfully.

6. The method according to claim 1, characterized in that, The method further includes: Simulate the operating environment of the relay under test to determine if the relay under test enters the identification mode; After detecting that the relay under test has executed an action command, the complex operating conditions of the relay under test are adjusted. Real-time monitoring of voltage monitoring data at the sampling points of the relay under test; Based on the voltage monitoring data, obtain the range of the ratio between the detected voltage at the second terminal of the relay under test and the battery pack voltage, as well as the rate of change of the ratio. From the ratio range data and the ratio change rate data, a first target range of possible changes in the ratio and a first target threshold range of possible values ​​of the ratio change rate are defined for the relay under test when it is in the closed state, and / or, a second target range of possible changes in the ratio and a second target threshold range of possible values ​​of the ratio change rate are defined for the relay under test when it is in the open state.

7. The method according to claim 6, characterized in that, The adjustment of the complex operating conditions of the relay under test includes: A variable resistor and a variable capacitor are randomly connected to the rear end of the relay under test or to the rear end of other relays under test that are linked to the relay under test. The insulation detection function can be turned on or off randomly.

8. A relay status diagnostic device, characterized in that, The first terminal of the relay under test is connected to either the positive or negative terminal of the battery pack, and the second terminal of the relay under test is connected to the load side; the device includes: The real-time detection module is used to detect the detection voltage data of the sampling point of the relay under test in real time after the relay under test executes the action command. The sampling point is located at the second end of the relay under test. The data processing module is used to obtain the range and rate of change of the ratio between the detected voltage at the second terminal of the relay under test and the battery pack voltage based on the detected voltage data. A state determination module is used to determine the actual state of the relay under test based on the ratio range and the ratio change rate. The status diagnosis module is used to perform status diagnosis on the relay under test based on the actual status and the action command.

9. A battery management system, characterized in that, The battery management system includes: Memory, used to store executable computer programs; A processor for calling and running the executable computer program from the memory, such that the processor performs the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the method as described in any one of claims 1 to 7.

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