Fault diagnosis system and fault diagnosis method for high-voltage contactor of electric vehicle

Abstract

The invention provides a fault diagnosis system and a fault diagnosis method for a high-voltage contactor of an electric vehicle, and relates to the technical field of electric vehicles. The system comprises a control device and a vehicle high-voltage system, and the vehicle high-voltage system at least comprises a cathode contactor, a voltage monitoring module, an insulation detection module and a load. And the control equipment is used for acquiring the voltage at the first voltage sampling point according to the state of each switch in the insulation detection module, and performing fault diagnosis on the cathode contactor according to the voltage at the first voltage sampling point and the power supply voltage to obtain a fault diagnosis result. According to the invention, fault diagnosis is carried out on the high-voltage contactor by introducing the switching action of the insulation detection module, so that the influence of load charging and discharging on the fault diagnosis of the high-voltage contactor is avoided, and whether the fault of the high-voltage contactor is a false fault or a real fault caused by load charging and discharging can be effectively distinguished; therefore, the accuracy of fault diagnosis of the high-voltage contactor is improved while the load charging and discharging interference is effectively eliminated.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, and more specifically, to a fault diagnosis system and method for electric vehicle high-voltage contactors. Background Technology

[0002] In the high-voltage system of electric vehicles, the contactor is a key component that controls the opening and closing of the high-voltage circuit. Its working status is directly related to the safe and reliable operation of the entire vehicle's high-voltage system. Therefore, accurate status monitoring and fault diagnosis of whether the contactor is properly disconnected is one of the core aspects of high-voltage safety management.

[0003] However, in practical applications, high-voltage systems are connected to power electronic devices such as motor controllers and battery management systems, which contain a large number of energy storage capacitors. Even after the contactor disconnects, these capacitors may still exhibit a brief voltage sustaining or reverse discharge phenomenon, resulting in a temporary voltage difference or a small current across the contactor. Clearly, this phenomenon is not caused by contactor contact sticking, but rather by the charging and discharging of the load-side capacitors. However, existing fault diagnosis methods struggle to effectively distinguish between such pseudo-faults and genuine contactor sticking faults, leading to false alarms. Therefore, effectively eliminating load-side capacitor charging and discharging interference and improving the accuracy of contactor status diagnosis is crucial. Summary of the Invention

[0004] The purpose of this application is to provide a fault diagnosis system and method for electric vehicle high-voltage contactors, addressing the shortcomings of the prior art, in order to solve the problem that the prior art is unable to effectively distinguish between such pseudo-faults and real contactor adhesion faults, thus causing false alarms.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: In a first aspect, embodiments of this application provide a fault diagnosis system for a high-voltage contactor in an electric vehicle, comprising: The control equipment and vehicle high-voltage system, wherein the vehicle high-voltage system includes at least: a negative contactor, a voltage monitoring module, an insulation detection module, and a load; The voltage monitoring module includes a first resistor and a second resistor; the insulation detection module includes at least one switch. One end of the negative contactor is connected to one end of the insulation detection module, and the other end of the negative contactor is connected to one end of the second resistor; One end of the load is connected to the other end of the insulation detection module, and the other end of the load is connected to one end of the second resistor; The other end of the second resistor is connected to one end of the first resistor, and the other end of the first resistor is used to connect to the power supply. A first voltage sampling point is provided between the other end of the second resistor and one end of the first resistor; The control device is used to collect the voltage at the first voltage sampling point according to the state of each switch in the insulation detection module, and to perform fault diagnosis on the negative contactor based on the voltage at the first voltage sampling point and the power supply voltage, so as to obtain the fault diagnosis result of the negative contactor.

[0006] As one possible implementation, the insulation detection module includes: a first switch, a second switch, a first resistor network, and a second resistor network, wherein the first resistor network includes a third resistor, a fourth resistor, and a fifth resistor, and the third resistor, the fourth resistor, and the fifth resistor are connected in series. One end of the first switch is connected to the line connecting the third resistor and the fourth resistor, one end of the third resistor is connected to one end of the battery pack in the vehicle high-voltage system, and one end of the fifth resistor is connected to one end of the negative contactor. One end of the second resistor network is connected to the line connecting the third resistor and the fourth resistor, and the other end of the second resistor network is connected to one end of the second switch, and the other end of the second switch is connected to one end of the negative contactor.

[0007] As one possible implementation, the vehicle high-voltage system further includes: a sixth resistor and a seventh resistor; One end of the sixth resistor is connected to one end of the battery pack, the other end of the sixth resistor is connected to the seventh resistor, the other end of the seventh resistor is connected to one end of the negative contactor, and the other end of the battery pack is connected to one end of the negative contactor. The other end of the first switch is connected to the line connecting the sixth resistor and the seventh resistor.

[0008] As one possible implementation, the control device is also used for: When the vehicle's high-voltage system is in the power-on initialization phase, if the first voltage and the second voltage at the first voltage sampling point are equal when the negative contactor is open, and both the first voltage and the second voltage are equal to the power supply voltage, and both the first voltage and the second voltage are within a first preset range during a first preset time period, then it is determined that the negative contactor has a contact sticking fault; wherein, the first voltage is the voltage collected when the first switch is closed and the second switch is open, and the second voltage is the voltage collected when both the first switch and the second switch are closed; When the vehicle high-voltage system is in the power-on phase, if the first voltage and the second voltage are both within the second preset range during the first preset time period when the negative contactor is closed, then it is determined that the negative contactor has an open circuit fault. When the vehicle's high-voltage system is in the power-off phase, and the negative contactor is disconnected, if the first voltage is equal to the second voltage, and both the first voltage and the second voltage are equal to the power supply voltage, and both the first voltage and the second voltage are within the first preset range during a second preset time period, then it is determined that the negative contactor has a contact sticking fault; wherein, the second preset time period is longer than the first preset time period.

[0009] As one possible implementation, the vehicle high-voltage system also includes a positive contactor; One end of the positive contactor is connected to one end of the battery pack in the vehicle's high-voltage system, and the other end of the positive contactor is connected to the load.

[0010] As one possible implementation, the vehicle high-voltage system further includes: a third resistor network, which includes an eighth resistor and a ninth resistor, one end of the eighth resistor being connected to one end of the positive contactor via a fuse unit, the other end of the eighth resistor being connected to one end of the ninth resistor, and the other end of the ninth resistor being connected to one end of the negative contactor; The control device is also used to: collect the voltage at the second voltage sampling point, and determine the total voltage of the battery pack based on the voltage at the second voltage sampling point, wherein the second voltage sampling point is the node between the eighth resistor and the ninth resistor.

[0011] As one possible implementation, the vehicle high-voltage system further includes: a fourth resistor network, the fourth resistor network including a tenth resistor and an eleventh resistor, one end of the tenth resistor being connected to one end of the positive contactor, the other end of the tenth resistor being connected to one end of the eleventh resistor, and the other end of the eleventh resistor being connected to one end of the negative contactor; The control device is further configured to: acquire the voltage at the third voltage sampling point and compare the voltage at the third voltage sampling point with the voltage at the second voltage sampling point; if the voltage at the third voltage sampling point is not equal to the voltage at the second voltage sampling point, then determine that the fuse unit has failed, wherein the third voltage sampling point is the node between the tenth resistor and the eleventh resistor.

[0012] As one possible implementation, the vehicle high-voltage system further includes: a fifth resistor network, the fifth resistor network including a twelfth resistor and a thirteenth resistor, one end of the twelfth resistor being connected to the other end of the positive contactor, the other end of the twelfth resistor being connected to one end of the thirteenth resistor, and the other end of the thirteenth resistor being connected to one end of the negative contactor; The control device is further configured to: acquire the voltage at the fourth voltage sampling point and compare the voltage at the fourth voltage sampling point with the voltage at the second voltage sampling point; if the voltage at the fourth voltage sampling point is equal to the voltage at the second voltage sampling point, then determine that the positive contactor is closed, wherein the fourth voltage sampling point is the node between the twelfth resistor and the thirteenth resistor.

[0013] As one possible implementation, the control device is also used for: When the vehicle high-voltage system is in the power-on initialization phase, if the voltage at the second voltage sampling point is within a third preset range when the positive contactor is disconnected, and the absolute value of the difference between the voltage at the fourth voltage sampling point and the voltage at the second voltage sampling point is less than or equal to the first voltage threshold during the third preset time period, then it is determined that the positive contactor has a contact sticking fault. The third preset range is determined based on the maximum and minimum voltages of the battery pack in the vehicle high-voltage system. When the vehicle high-voltage system is in the power-on phase, if the voltage at the second voltage sampling point is within the third preset range when the positive contactor is closed, and the absolute value of the difference between the voltage at the fourth voltage sampling point and the voltage at the second voltage sampling point is greater than or equal to the second voltage threshold during the third preset time period, then it is determined that the positive contactor has an open circuit fault. When the vehicle's high-voltage system is in the power-off phase, and when the positive contactor is disconnected, if the voltage at the second voltage sampling point is within the third preset range, and the absolute value of the difference between the voltage at the fourth voltage sampling point and the voltage at the second voltage sampling point is less than or equal to the first voltage threshold during the fourth preset time period, then it is determined that the positive contactor has a contact sticking fault, wherein the fourth preset time period is longer than the third preset time period.

[0014] In a second aspect, embodiments of this application provide a method for diagnosing faults in high-voltage contactors of electric vehicles, applied to a control device in a high-voltage contactor fault diagnosis system for electric vehicles as described in any one of the first aspects, the method comprising: Based on the state of each switch in the insulation detection module, the voltage at the first voltage sampling point is collected; Based on the voltage at the first voltage sampling point and the power supply voltage, fault diagnosis is performed on the negative contactor to obtain the fault diagnosis result of the negative contactor.

[0015] Thirdly, embodiments of this application provide a control device, including: a processor, a storage medium, and a bus. The storage medium stores machine-readable instructions executable by the processor. When the control device is running, the processor communicates with the storage medium via the bus, and the processor executes the machine-readable instructions to perform the steps of the electric vehicle high-voltage contactor fault diagnosis method as described in the second aspect above.

[0016] Fourthly, another embodiment of this application provides a storage medium storing a computer program, which, when executed by a processor, performs the steps of the electric vehicle high-voltage contactor fault diagnosis method described in the second aspect above.

[0017] According to the electric vehicle high-voltage contactor fault diagnosis system and method of this application, the control device controls the switching action of each switch included in the insulation detection module of the vehicle's high-voltage system, and collects the voltage at each voltage sampling point in the vehicle's high-voltage system. Then, based on the voltage at each voltage sampling point and the switching state of each switch included in the insulation detection module, fault diagnosis is performed on the high-voltage contactors in the vehicle's high-voltage system, such as the positive and negative contactors. Thus, by introducing the switching action of the insulation detection module to diagnose the high-voltage contactor faults during the fault diagnosis process, the influence of load charging and discharging on the high-voltage contactor fault diagnosis is avoided. This effectively distinguishes between false faults and real faults caused by load charging and discharging of the high-voltage contactor, thereby improving the accuracy of high-voltage contactor fault diagnosis while effectively eliminating load charging and discharging interference. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a vehicle high-voltage system provided in an embodiment of this application is shown; Figure 2 A schematic diagram of another vehicle high-voltage system provided in an embodiment of this application is shown; Figure 3 A schematic diagram of another vehicle high-voltage system provided in an embodiment of this application is shown; Figure 4 A flowchart illustrating a fault diagnosis method for a high-voltage contactor in an electric vehicle provided in an embodiment of this application is shown. Figure 5 A flowchart illustrating a fault diagnosis method for a negative contactor provided in an embodiment of this application is shown. Figure 6 A schematic diagram of the structure of a control device provided in an embodiment of this application is shown. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0021] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0022] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0023] In this embodiment, the electric vehicle high-voltage contactor fault diagnosis system includes a control device and a vehicle high-voltage system, which are communicatively connected. The control device controls the switching actions of each switch included in the insulation detection module of the vehicle high-voltage system, and collects the voltage at each voltage sampling point in the vehicle high-voltage system. Based on the voltage at each sampling point and the switching status of each switch included in the insulation detection module, fault diagnosis is performed on the high-voltage contactors, such as the positive and negative contactors, in the vehicle high-voltage system. Thus, by introducing the switching actions of the insulation detection module to diagnose the high-voltage contactor faults during the fault diagnosis process, the influence of load charging and discharging on the fault diagnosis of the high-voltage contactor is avoided. This effectively distinguishes between false faults and real faults caused by load charging and discharging of the high-voltage contactor, thereby improving the accuracy of high-voltage contactor fault diagnosis while effectively eliminating load charging and discharging interference.

[0024] Figure 1 A schematic diagram of a vehicle high-voltage system according to an embodiment of this application is shown. (Refer to...) Figure 1 As shown, the vehicle's high-voltage system includes at least: a negative contactor 10, a voltage monitoring module 11, an insulation detection module 12, and a load 13. The voltage monitoring module 11 includes a first resistor and a second resistor, as shown in the figure. Figure 1 As shown, the first resistor is R1, the second resistor is R2, and the insulation detection module 12 includes at least one switch.

[0025] Optionally, refer to Figure 1 As shown, one end of the negative contactor 10 is connected to one end of the insulation detection module 12, and the other end of the negative contactor 10 is connected to one end of the second resistor R2. One end of the load 13 is connected to the other end of the insulation detection module 12, and the other end of the load 13 is connected to one end of the second resistor R2. The other end of the second resistor R2 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is used to connect to the power supply VCC.

[0026] Optionally, a first voltage sampling point is provided between the other end of the second resistor R2 and one end of the first resistor R1, such that the first voltage sampling point is as follows: Figure 2 As shown in the figure, AD1. Based on this, the control device can collect the voltage at the first voltage sampling point AD1 according to the state of each switch in the insulation detection module 12, and perform fault diagnosis on the negative contactor 10 according to the voltage at the first voltage sampling point AD1 and the power supply voltage (voltage of power supply VCC), thereby obtaining the fault diagnosis result of the negative contactor 10.

[0027] Optionally, the circuit structure connected to the vehicle's high-voltage system changes when each switch in the insulation detection module 12 is in a different switching state. Based on this, the control device specifically collects the voltage at the first voltage sampling point AD1 in the corresponding state when each switch in the insulation detection module 12 is in a different switching state, compares the voltage at the first voltage sampling point AD1 with the power supply voltage, and performs fault diagnosis on the negative contactor 10 based on the comparison result. This determines whether the negative contactor 10 has a sticking fault or an open circuit fault, and, if the negative contactor 10 has a sticking fault, effectively distinguishes whether the sticking fault is a pseudo-fault caused by load charging and discharging or a real contact sticking fault.

[0028] Figure 2 A schematic diagram of another vehicle high-voltage system provided in an embodiment of this application is shown. (Refer to...) Figure 2 As shown, the insulation detection module 12 includes: a first switch S1, a second switch S2, a first resistor network 121, and a second resistor network 122. The first resistor network 121 includes a third resistor R3, a fourth resistor R4, and a fifth resistor R5, which are connected in series.

[0029] Optionally, one end of the first switch S1 is connected to the line connecting the third resistor R3 and the fourth resistor R4, one end of the third resistor R3 is connected to one end of the battery pack 14 in the vehicle's high-voltage system, and one end of the fifth resistor R5 is connected to one end of the negative contactor 10.

[0030] Optionally, refer to Figure 2 As shown, the vehicle's high-voltage system also includes a sixth resistor R6 and a seventh resistor R7. One end of the sixth resistor R6 is connected to one end of the battery pack 14, specifically to the positive terminal of the battery pack 14. The other end of the sixth resistor R6 is connected to the seventh resistor R7. The other end of the seventh resistor R7 is connected to one end of the negative contactor 10. The other end of the battery pack 14, i.e., the negative terminal of the battery pack 14, is connected to one end of the negative contactor 10. The other end of the first switch S1 is connected to the line connecting the sixth resistor R6 and the seventh resistor R7.

[0031] Optionally, continue to refer to Figure 2 As shown, the second resistor network 122 includes a resistor R8. One end of the resistor R8 is connected to the line connecting the third resistor R3 and the fourth resistor R4. The other end of the resistor R8 is connected to one end of the second switch S2. The other end of the second switch S2 is connected to one end of the negative contactor 10, specifically to the front end of the negative contactor 10.

[0032] Figure 3 A schematic diagram of another vehicle high-voltage system provided in an embodiment of this application is shown. (Refer to...) Figure 3As shown, the vehicle high-voltage system also includes a positive contactor 15, and the load 13 includes capacitors C1, C2 and C3, wherein capacitors C2 and C3 are connected in series, and capacitors C2 and C3 are connected in parallel with capacitor C1 after being connected in series.

[0033] Optionally, one end of the positive contactor 15 is connected to one end of the battery pack 14, and the other end of the positive contactor 15 is connected to one end of capacitor C1 and capacitor C2 respectively.

[0034] Optionally, continue to refer to Figure 3 As shown, the vehicle high-voltage system also includes a third resistor network, which includes an eighth resistor R9 and a ninth resistor R10. One end of the eighth resistor R9 is connected to one end of the positive contactor 15 through a fuse unit FUSE, specifically to the front end of the positive contactor 15. The other end of the eighth resistor R9 is connected to one end of the ninth resistor R10, and the other end of the ninth resistor R10 is connected to one end of the negative contactor 10, specifically to the front end of the negative contactor 10.

[0035] Optionally, continue to refer to Figure 3 As shown, the vehicle high-voltage system also includes a fourth resistor network, which includes a tenth resistor R11 and an eleventh resistor R12. A switch K0 is provided between the tenth resistor R11 and the eleventh resistor R12. One end of the tenth resistor R11 is connected to one end of the positive contactor 15, specifically to the front end of the positive contactor 15. The other end of the tenth resistor R11 is connected to one end of the eleventh resistor R12. The other end of the eleventh resistor R11 is connected to one end of the negative contactor 10, specifically to the front end of the negative contactor 10.

[0036] Optionally, continue to refer to Figure 3 As shown, the vehicle high-voltage system also includes: a fifth resistor network, which includes a twelfth resistor R13 and a thirteenth resistor R14. A switch K1 is provided between the twelfth resistor R13 and the thirteenth resistor R14. One end of the twelfth resistor R13 is connected to the other end of the positive contactor 15, specifically to the rear end of the positive contactor 15. The other end of the twelfth resistor R13 is connected to one end of the thirteenth resistor R14. The other end of the thirteenth resistor R14 is connected to one end of the negative contactor 10, specifically to the front end of the negative contactor 10.

[0037] Furthermore, continue to refer to Figure 3 As shown, the vehicle's high-voltage system also includes a second voltage sampling point AD2, a third voltage sampling point AD3, and a fourth voltage sampling point AD4. Based on this, the control device can collect the voltage at the second voltage sampling point AD2 and determine the total voltage of the battery pack 14 according to the voltage at the second voltage sampling point AD2.

[0038] For example, refer to Figure 3 As shown, the eighth resistor R9 and the ninth resistor R10 form a voltage divider circuit, which can be used to safely reduce the total voltage of the battery pack 14 to a measurable range. For example, if the resistance ratio of the eighth resistor R9 to the ninth resistor R10 is 1:1, the voltage at the second voltage sampling point AD2 will be approximately half of the total voltage of the battery pack 14. Assuming the total voltage of the battery pack 14 is 500V, the voltage measured at the second voltage sampling point AD2 after voltage division will be approximately 250V. Then, through sampling and conversion, the actual total voltage of the battery pack 14 can be obtained.

[0039] Optionally, the control device may also collect the voltage at the third voltage sampling point AD3 and compare the voltage at the third voltage sampling point AD3 with the voltage at the second voltage sampling point AD2; if the voltage at the third voltage sampling point AD3 is not equal to the voltage at the second voltage sampling point AD2, it is determined that the fuse unit FUSE has failed.

[0040] For example, refer to Figure 3 As shown, the tenth resistor R11 and the eleventh resistor R12 also form a voltage divider network to monitor the voltage difference across the fuse unit (e.g., a fuse). When the fuse is conducting normally, there is no voltage drop between points B and C, and the voltage sampled at the third voltage sampling point AD3 is close to zero or a very small value, such as a few millivolts, indicating a good circuit path. However, if the fuse blows due to overcurrent, an open circuit occurs between points B and C. In this case, the third voltage sampling point AD3 will detect a higher voltage. For example, when the second voltage sampling point AD2 measures 500V, the third voltage sampling point AD3 may measure close to 200V, indicating that current cannot pass through the fuse, meaning the fuse is damaged. Thus, by comparing the voltage values ​​at the second voltage sampling point AD2 and the third voltage sampling point AD3, the control device can determine whether the fuse is intact, thereby triggering an alarm or taking protective measures in a timely manner.

[0041] Optionally, the control device may also collect the voltage at the fourth voltage sampling point AD4 and compare the voltage at the fourth voltage sampling point AD4 with the voltage at the second voltage sampling point AD2. If the voltage at the fourth voltage sampling point AD4 is equal to the voltage at the second voltage sampling point AD2, then the positive contactor 15 is determined to be closed.

[0042] For example, refer to Figure 3As shown, the twelfth resistor R13 and the thirteenth resistor R14 form another voltage divider circuit to monitor the state of the positive contactor 15. When the positive contactor 15 is closed, the path between points A and C is open. If the voltage at point A is 500V, the voltage at point C should also be close to 500V. At this time, the voltage sampled at the fourth voltage sampling point AD4 will also be relatively high. When the positive contactor 15 is open, the voltage at point C drops to near ground potential, and the voltage sampled at the fourth voltage sampling point AD4 is close to 0V. Therefore, the voltage value at the fourth voltage sampling point AD4 can be used to determine whether the positive contactor 15 is in the closed state. In this way, it can be confirmed whether the high-voltage circuit is connected, ensuring that the system starts or operates under safe conditions.

[0043] Optionally, continue to refer to Figure 3 As shown, the vehicle's high-voltage system also includes a fifth voltage sampling point AD5. The insulation detection module 12, through switching the on / off states of the first switch S1 and the second switch S2, combined with the voltage sampling at the third resistor R3, the fourth resistor R4, the fifth resistor R5, the resistor R8, and the fifth voltage sampling point AD5, can measure the resistance values ​​of the sixth resistor R6 and the seventh resistor R7. Specifically, when the first switch S1 is closed and the second switch S2 is open, the fifth resistor R5 and the resistor R8 are not connected. The voltage sampled at the fifth voltage sampling point AD5 is determined by the voltage division relationship formed by the sixth resistor R6, the third resistor R3, and the fourth resistor R4, from which the first voltage equation can be derived. When both the first switch S1 and the second switch S2 are closed, the fifth resistor R5 and the resistor R8 are connected in parallel. The voltage sampled at the fifth voltage sampling point AD5 is affected by the fifth resistor R5 and the resistor R8, changing the overall voltage division ratio, from which the second voltage equation can be derived. Based on this, by simultaneously solving the first voltage equation and the second voltage equation under the above two different states, the resistance values ​​of the sixth resistor R6 and the seventh resistor R7 can be obtained.

[0044] Based on this, the electric vehicle high-voltage contactor fault diagnosis system provided in the embodiments of this application can safely and accurately obtain the battery total voltage, fuse on / off status and positive contactor switch status without direct contact with high voltage, and promptly detect faults such as open circuit and open circuit, significantly improving the system's safety, reliability and fault diagnosis capability.

[0045] The following is in conjunction with the above. Figures 1 to 3 The description of the high-voltage system in the vehicle shown in this application provides a detailed explanation of the electric vehicle high-voltage contactor fault diagnosis method provided in the embodiments of this application.

[0046] Figure 4 This illustration shows a flowchart of a fault diagnosis method for a high-voltage contactor in an electric vehicle according to an embodiment of this application. The execution subject of this method is the control equipment in the fault diagnosis system for the high-voltage contactor in an electric vehicle. (Refer to...) Figure 4 As shown, the method specifically includes the following steps: S401. Based on the status of each switch in the insulation detection module, collect the voltage at the first voltage sampling point.

[0047] Optionally, in the vehicle's high-voltage system, the insulation detection module 12 controls the on / off states of the first switch S1 and the second switch S2 to change the circuit connection method, thereby achieving voltage measurement under different paths. The first voltage sampling point AD1 is located between the power supply VCC and the voltage divider network formed by the first resistor R1 and the second resistor R2. The voltage value of the first voltage sampling point AD1 is affected by the state of the negative contactor 10 and the load 13. When the first switch S1 and the second switch S2 are in different combined states, such as the first switch S1 being closed and the second switch S2 being open, or both the first switch S1 and the second switch S2 being closed, the current path changes, causing the voltage at the first voltage sampling point AD1 to change accordingly.

[0048] For example, when the first switch S1 is closed and the second switch S2 is open, the fifth resistor R5 and resistor R8 are not connected, and the voltage at the first voltage sampling point AD1 is determined by the first resistor R1, the second resistor R2, and the load circuit. However, when the second switch S2 is closed, resistor R8 is connected in parallel, changing the overall impedance distribution and thus affecting the voltage at the first voltage sampling point AD1. In this way, the control device monitors the voltage at the first voltage sampling point AD1 in real time under different switching states and records the sampling data under different switching configurations, providing crucial input for subsequent fault diagnosis.

[0049] S402. Based on the voltage at the first voltage sampling point and the power supply voltage, perform fault diagnosis on the negative contactor and obtain the fault diagnosis result of the negative contactor.

[0050] Optionally, refer to Figure 3 As shown, the resistance values ​​of the first resistor R1 and the second resistor R2 are equal. The relationship between the voltage at the first voltage sampling point AD1 and the first resistor R1, the second resistor R2, and the power supply voltage VCC is shown in the following expression (1): (1) in, This represents the voltage at the first voltage sampling point AD1. Indicates the power supply voltage. This indicates the resistance value of the first resistor R1. This indicates the resistance value of the second resistor, R2.

[0051] Optionally, the control device, based on the voltage at the first voltage sampling point AD1 acquired from multiple switching states, combines the known power supply voltage... Combined with the correlation shown in the above expression (1), that is, under ideal conditions of no load interference, negative contactor 10 disconnected and normal insulation, the voltage at the first voltage sampling point AD1 should be stable at the power supply voltage. Half of the value. Based on this, the control device can accurately analyze the operating status of the negative contactor 10. For example, if the voltage at the first voltage sampling point AD1 is abnormally low when the first switch S1 is closed and the second switch S2 is open, it indicates that the negative contactor may have a sticking fault, that is, the contacts cannot open normally, resulting in a short circuit between the high voltage side and ground. If the voltage at the first voltage sampling point AD1 remains unchanged after the second switch S2 is closed, it may indicate that the negative contactor 10 has an open circuit fault, that is, the contacts of the negative contactor 10 cannot close, resulting in a closed circuit.

[0052] Furthermore, by comparing the voltage change trends under different switching states, it is possible to distinguish whether the adhesion is due to a transient pseudo-fault caused by load charging and discharging or genuine mechanical adhesion. For example, if the voltage fluctuation only occurs during the load dynamic process and recovers over time, it is a pseudo-fault; if the voltage remains consistently low, it is determined to be genuine adhesion. In this way, high-precision diagnosis of the state of the negative contactor 10 is achieved, improving the safety and reliability of the entire vehicle's electrical system.

[0053] As one possible implementation, when the vehicle's high-voltage system is in the power-on initialization phase, if the first voltage and the second voltage at the first voltage sampling point AD1 are equal when the negative contactor 10 is disconnected, and both the first voltage and the second voltage are equal to the power supply voltage, and both the first voltage and the second voltage are within the first preset range during the first preset time period, then it is determined that the negative contactor 10 has a contact sticking fault.

[0054] Optionally, the first voltage is the voltage collected when the first switch S1 is closed and the second switch S2 is open, and the second voltage is the voltage collected when both the first switch S1 and the second switch S2 are closed.

[0055] For example, the first preset time period is T1, and the first preset range is 1V-1.5V, as shown in the reference. Figure 3 As shown, the power supply voltage is VCC voltage. During the power-on initialization phase of the vehicle's high-voltage system, the negative contactor 10 should be in the open state, at which time there should be no conductive path between the entire high-voltage circuit and ground. Under this premise, if the first voltage collected when the first switch S1 is closed and the second switch S2 is open is equal to the second voltage collected when the first switch S1 is closed and both the first switch S1 and the second switch S2 are closed, and both are equal to the power supply voltage... This indicates that the first voltage sampling point AD1 did not exhibit the expected half-power supply voltage division state, but was instead pulled high to the power supply voltage, indicating an abnormal conduction path on the load capacitor side. Since the negative contactor 10 should have been disconnected at this time, but its back end was still pulled high, it is highly likely that its contacts have physically stuck together, causing the vehicle's high-voltage system to be connected to the downstream circuit without being instructed to close.

[0056] Furthermore, if the voltage state of the sampled voltage at the first voltage sampling point AD1 remains stable within the first preset time period T1 (e.g., 100ms~500ms) and falls within the first preset range of 1V-1.5V, then the influence of transient interference or measurement noise is eliminated, and the control equipment can determine that the negative contactor 10 has experienced a real contact sticking fault. Based on this, through multi-state voltage comparison and time window verification, the accuracy and reliability of fault identification are effectively improved, misjudgment of faults is avoided, and high-voltage safety hazards are detected in time before vehicle startup, ensuring the safety of personnel and equipment.

[0057] Figure 5 A schematic flowchart of a fault diagnosis method for a negative contactor provided in an embodiment of this application is shown. (Refer to...) Figure 5 As shown, when the vehicle's high-voltage system is in the power-on initialization phase, to accurately diagnose whether the negative contactor 10 has a contact sticking fault, a 500ms delay is first set to determine if the vehicle's sleep time after the last power-off exceeds 60 seconds, ensuring that the load-side capacitor has fully discharged and avoiding residual voltage interference in the judgment. Subsequently, timing Ti is started and incremented every 10ms. Within a cumulative period of less than 100 times, i.e., 1000ms, the contact detection voltage of the negative contactor 10 and the voltage U at the first voltage sampling point AD5 are continuously collected, and the maximum value Umax and minimum value Umin of the voltage U at the first voltage sampling point AD1 are calculated. If the voltage U at the first voltage sampling point AD1 is always within the sticking threshold range, which is the aforementioned first threshold range of 1V - 1.5V, and |Umax - Umin| < 5mV, it indicates that the voltage is stable without fluctuation, and a preliminary judgment is made that sticking may exist.

[0058] Furthermore, to further eliminate false diagnoses of adhesion caused by the charging and discharging of the downstream capacitors and to enable the insulation detection function, the first switch S1 and the second switch S2 periodically operate to actively disturb the charging and discharging process of capacitors C1, C2, and C3 in the vehicle's high-voltage system. During this period, the voltage U at the first voltage sampling point AD5 is collected 20 times. If the voltage U at the first voltage sampling point AD5 satisfies |U - Umin| < 15mV and |Umax - U| < 15mV each time, it indicates that the voltage remains highly stable even under external dynamic interference, proving that the high level is not a transient phenomenon, but a continuous conduction caused by physical contact adhesion. In this way, through the dual mechanism of static observation combined with dynamic disturbance verification, the true adhesion and false capacitor discharge faults are effectively distinguished, significantly improving the diagnostic accuracy and reliability.

[0059] As one possible implementation, when the vehicle's high-voltage system is energized, if the first voltage and the second voltage are both within the second preset range during the first preset time period when the negative contactor 10 is closed, then it is determined that the negative contactor has an open circuit fault.

[0060] Optionally, the first preset time period is T1, and the second preset range is 2V-3V. During the power-on phase of the vehicle's high-voltage system, when the control device has issued a command to close the negative contactor 10, the high-voltage circuit should normally be connected. The insulation detection module 12 can form a predictable voltage division relationship at the first voltage sampling point AD1 by switching the different states of the first switch S1 and the second switch S2. If the first voltage sampled when the first switch S1 is closed and the second switch S2 is open, and the second voltage sampled when both the first switch S1 and the second switch S2 are closed, remain within the second preset range of 2V~3V within the first preset time T1, it indicates that the voltage at the first voltage sampling point AD1 has not reached the theoretically close level to the power supply voltage. Instead of being half of the expected value, it was limited to an abnormally low intermediate range, indicating that although the negative contactor 10 received the closing command, it did not actually conduct.

[0061] In this situation, it indicates that the current cannot form an effective circuit through the negative contactor 10, meaning the contacts of the negative contactor 10 have failed to close properly. The control equipment can then determine that the negative contactor 10 has an open-circuit fault. Thus, by setting a time window and voltage threshold range, transient fluctuations or noise interference can be eliminated, ensuring the stability and accuracy of fault diagnosis results. This allows for timely identification of contactor failure during the power-on phase of the vehicle's high-voltage system, preventing system failure to power on or damage to subsequent components due to a closed circuit, thereby improving overall vehicle safety and reliability.

[0062] As one possible implementation, when the vehicle's high-voltage system is in the power-off phase, if the first voltage and the second voltage are equal when the negative contactor 10 is disconnected, and both the first voltage and the second voltage are equal to the power supply voltage, and both the first voltage and the second voltage are within the first preset range during the second preset time period, then it is determined that the negative contactor has a contact sticking fault.

[0063] Optionally, the second preset time period T2 is greater than the first preset time period T1. When the vehicle's high-voltage system is in the power-off phase, the negative contactor 10 should be disconnected, and the main circuit between the vehicle's high-voltage system and the subsequent circuit should be cut off. Ideally, the sampling point of the insulation detection module 12 should not be pulled up by the high-voltage side. However, if the first voltage collected when the first switch S1 is closed and the second switch S2 is open while the negative contactor 10 is open, and the second voltage collected when both the first switch S1 and the second switch S2 are closed, and both are equal to the power supply voltage... This indicates that the potential at the first voltage sampling point AD1 has been abnormally pulled up to the power supply voltage. If the voltage does not exhibit the characteristics of a normal disconnection state, such as half or lower of the power supply voltage, it indicates that there is still a continuous conduction path on the high-voltage negative side.

[0064] Furthermore, if the voltage state of the sampled voltage at the first voltage sampling point AD1 remains stable and within the first preset range during the second preset time period T2, such as 500ms to 1s, transient interference can be ruled out, and it can be determined that the contacts of the negative contactor 10 have failed to separate normally, i.e., the negative contactor 10 has experienced a contact sticking fault. In other words, even if the control equipment has issued a command to disconnect the negative contactor, the high voltage continues to supply power through the sticking contacts, posing a serious safety risk. Thus, by jointly judging the consistency and stability of the multi-state voltage during the power-off phase, accurate identification of the sticking fault is achieved, which helps to trigger alarms or protection mechanisms in a timely manner and ensure electrical safety during vehicle maintenance and parking.

[0065] As one possible implementation, when the vehicle's high-voltage system is in the power-on initialization phase, if the voltage at the second voltage sampling point AD2 is within the third preset range when the positive contactor 15 is disconnected, and the absolute value of the difference between the voltage at the fourth voltage sampling point AD4 and the voltage at the second voltage sampling point AD2 is less than or equal to the first voltage threshold during the third preset time period, then it is determined that the positive contactor has a contact sticking fault.

[0066] Optionally, the third preset time period is T3, and the first voltage threshold is, for example, 10V. During the power-on initialization phase of the vehicle's high-voltage system, the positive contactor 15 should be in the open state, and there should be no conductive path between the positive terminal of the battery pack 14 and the downstream load 13. Under normal circumstances, the second voltage sampling point AD2 should be able to detect the complete battery voltage, while the voltage of the fourth voltage sampling point AD4 should be close to 0V or at an extremely low level due to the disconnection at the front end. If the voltage at the second voltage sampling point AD2 is within the third preset range, such as being close to the actual battery voltage, it indicates that the battery is normally powered on. However, if the voltage at the fourth voltage sampling point AD4 is very close to the voltage at the second voltage sampling point AD2 within 500ms during the third preset time period T3, and the absolute value of the difference between the two is less than or equal to the first voltage threshold of 10V, it indicates that the back end of the positive contactor 15 is abnormally pulled up to the total battery voltage.

[0067] In other words, under these circumstances, although the control equipment requires the positive contactor 15 to disconnect, the contacts of the positive contactor 15 are actually still in a conductive state, causing high voltage to be continuously transmitted to the load 13 side, i.e., the positive contactor 15 has experienced contact adhesion failure. Therefore, by continuously monitoring the voltage difference between the second voltage sampling point AD2 and the fourth voltage sampling point AD4 during the vehicle's high-voltage system power-on initialization phase, and combining this with a time window to determine its stability, transient interference can be effectively eliminated, physical adhesion can be accurately identified, and potential safety hazards on the positive side can be detected in time before the vehicle starts, preventing unexpected power-on.

[0068] Optionally, the third preset range is determined based on the maximum and minimum voltages of the battery pack in the vehicle's high-voltage system, and is used to determine whether the voltage at the second voltage sampling point AD2 is within a reasonable range. Specifically, if the nominal voltage range of the battery pack 14 is 300V to 500V, the third preset range can be set to a range slightly wider than this range, such as 290V to 510V, to cover the instantaneous voltage fluctuations of the battery pack 14 under extreme operating conditions. It is worth noting that the setting of the third preset range can not only be based on the electrical characteristics of the battery pack itself, but also comprehensively consider sampling errors, voltage sensor measurement deviations, and instantaneous overvoltage or undervoltage phenomena caused by temperature changes, load changes, etc., in the vehicle's high-voltage system. By appropriately relaxing the boundaries, it avoids misjudging normal fluctuations as faults, thereby improving the robustness and accuracy of system diagnosis, ensuring that alarms are triggered only when the voltage is severely abnormal, and guaranteeing the stable operation of the vehicle's high-voltage system.

[0069] As one possible implementation, when the vehicle's high-voltage system is powered on, if the voltage at the second voltage sampling point AD2 is within the third preset range when the positive contactor 15 is closed, and the absolute value of the difference between the voltage at the fourth voltage sampling point AD4 and the voltage at the second voltage sampling point AD2 is greater than or equal to the second voltage threshold during the third preset time period, then it is determined that the positive contactor has an open circuit fault.

[0070] Optionally, the third preset time period is T3, and the second voltage threshold is 20V. When the vehicle's high-voltage system is powered on, the positive contactor 15 should have received a closing command and be conducting, allowing the battery pack 14 to normally transfer electrical energy to the downstream load 13. At this time, if the total battery voltage detected at the second voltage sampling point AD2 is within the third preset range determined based on the minimum and maximum voltages of the battery pack 14, it indicates that the battery-side voltage is normal. Simultaneously, the voltage collected at the fourth voltage sampling point AD4 under normal conditions should be basically consistent with the voltage at the second voltage sampling point AD2. However, if, during the third preset time period T3, the absolute value of the voltage difference between the fourth voltage sampling point AD4 and the second voltage sampling point AD2 is continuously greater than or equal to the second voltage threshold of 20V, it indicates that the downstream end of the positive contactor 15 has not been effectively pulled up to the battery voltage, meaning the load side has not received the necessary high-voltage power supply.

[0071] In other words, under these circumstances, although the control equipment has closed the positive contactor 15, the contacts of the positive contactor 15 are not actually conducting, and the current path remains open. Therefore, the control equipment can determine that the positive contactor 15 has an open-circuit fault. Thus, through dual-point voltage comparison and time window verification, abnormalities such as contactor drive failure and contact erosion can be effectively identified, ensuring timely detection of circuit faults during the power-on process of the vehicle's high-voltage system, preventing equipment from starting incorrectly or malfunctioning, and improving overall vehicle safety and operational reliability.

[0072] As one possible implementation, when the vehicle's high-voltage system is in the power-off phase, if the voltage at the second voltage sampling point AD2 is within the third preset range when the positive contactor 15 is disconnected, and the absolute value of the difference between the voltage at the fourth voltage sampling point AD4 and the voltage at the second voltage sampling point is less than or equal to the first voltage threshold during the fourth preset time period, then it is determined that the positive contactor 15 has a contact sticking fault.

[0073] Optionally, the fourth preset time period T4 is longer than the third preset time period T3. When the vehicle's high-voltage system is in the power-down phase, the positive contactor 15 should be disconnected, and the connection between the battery's high-voltage positive terminal and the downstream load 13 is broken. At this time, the second voltage sampling point AD2 can still detect the battery pack voltage through the front-end voltage divider network. As long as it is within the third preset range based on the battery's minimum / maximum voltage and considering error relaxation, it indicates that the battery-side voltage is normal. The fourth voltage sampling point AD4 is located at the rear end of the positive contactor 15. Under normal circumstances, its voltage should approach zero or a very low value due to the circuit being disconnected, resulting in a significant voltage difference with the second voltage sampling point AD2. However, if, during the fourth preset time period T4, such as within 800ms, the absolute value of the voltage difference between the fourth voltage sampling point AD4 and the second voltage sampling point AD2 remains less than or equal to the first voltage threshold of 10V, it indicates that the rear end of the positive contactor 15 still maintains a high potential close to the battery voltage, meaning that the high-voltage electricity is still being continuously output and has not been physically disconnected. Furthermore, since the fourth preset time period T4 is longer than the third preset time period T3, sufficient time can be allowed for the system to discharge completely, eliminating transient effects such as residual capacitor voltage. Therefore, under the above circumstances, it can be clearly determined that the positive contactor 15 has a contact sticking fault. In this way, by extending the monitoring time, the reliability of the judgment is improved, ensuring that the high-voltage system is truly disconnected after the vehicle is powered off, preventing serious safety accidents such as leakage and spontaneous combustion, and ensuring the safety of maintenance and parking.

[0074] This application embodiment also provides a control device 600, such as... Figure 6 The diagram shown is a structural schematic of a control device 600 provided in an embodiment of this application, including: a processor 601 and a memory 602, and optionally, a bus 603. The memory 602 stores machine-readable instructions executable by the processor 601. When the control device 600 is running, the processor 601 and the memory 602 communicate via the bus 603. When the machine-readable instructions are executed by the processor 601, the steps of the electric vehicle high-voltage contactor fault diagnosis method described in any of the preceding claims are performed.

[0075] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps of the electric vehicle high-voltage contactor fault diagnosis method as described in any of the preceding claims.

[0076] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some communication interfaces; the indirect coupling or communication connection of devices or modules can be electrical, mechanical, or other forms.

[0077] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0078] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A fault diagnosis system for high-voltage contactors in electric vehicles, characterized in that, include: The control equipment and vehicle high-voltage system, wherein the vehicle high-voltage system includes at least: a negative contactor, a voltage monitoring module, an insulation detection module, and a load; The voltage monitoring module includes a first resistor and a second resistor; the insulation detection module includes at least one switch. One end of the negative contactor is connected to one end of the insulation detection module, and the other end of the negative contactor is connected to one end of the second resistor; One end of the load is connected to the other end of the insulation detection module, and the other end of the load is connected to one end of the second resistor; The other end of the second resistor is connected to one end of the first resistor, and the other end of the first resistor is used to connect to the power supply. A first voltage sampling point is provided between the other end of the second resistor and one end of the first resistor; The control device is used to collect the voltage at the first voltage sampling point according to the state of each switch in the insulation detection module, and to perform fault diagnosis on the negative contactor based on the voltage at the first voltage sampling point and the power supply voltage, so as to obtain the fault diagnosis result of the negative contactor.

2. The system according to claim 1, characterized in that, The insulation detection module includes: a first switch, a second switch, a first resistor network, and a second resistor network. The first resistor network includes a third resistor, a fourth resistor, and a fifth resistor, and the third resistor, the fourth resistor, and the fifth resistor are connected in series. One end of the first switch is connected to the line connecting the third resistor and the fourth resistor, one end of the third resistor is connected to one end of the battery pack in the vehicle high-voltage system, and one end of the fifth resistor is connected to one end of the negative contactor. One end of the second resistor network is connected to the line connecting the third resistor and the fourth resistor, and the other end of the second resistor network is connected to one end of the second switch, and the other end of the second switch is connected to one end of the negative contactor.

3. The system according to claim 2, characterized in that, The vehicle high-voltage system also includes: a sixth resistor and a seventh resistor; One end of the sixth resistor is connected to one end of the battery pack, the other end of the sixth resistor is connected to the seventh resistor, the other end of the seventh resistor is connected to one end of the negative contactor, and the other end of the battery pack is connected to one end of the negative contactor. The other end of the first switch is connected to the line connecting the sixth resistor and the seventh resistor.

4. The system according to claim 2, characterized in that, The control device is also used for: When the vehicle's high-voltage system is in the power-on initialization phase, if the first voltage and the second voltage at the first voltage sampling point are equal when the negative contactor is open, and both the first voltage and the second voltage are equal to the power supply voltage, and both the first voltage and the second voltage are within a first preset range during a first preset time period, then it is determined that the negative contactor has a contact sticking fault; wherein, the first voltage is the voltage collected when the first switch is closed and the second switch is open, and the second voltage is the voltage collected when both the first switch and the second switch are closed; When the vehicle high-voltage system is in the power-on phase, if the first voltage and the second voltage are both within the second preset range during the first preset time period when the negative contactor is closed, then it is determined that the negative contactor has an open circuit fault. When the vehicle's high-voltage system is in the power-off phase, and the negative contactor is disconnected, if the first voltage is equal to the second voltage, and both the first voltage and the second voltage are equal to the power supply voltage, and both the first voltage and the second voltage are within the first preset range during a second preset time period, then it is determined that the negative contactor has a contact sticking fault; wherein, the second preset time period is longer than the first preset time period.

5. The system according to claim 1, characterized in that, The vehicle high-voltage system also includes a positive contactor; One end of the positive contactor is connected to one end of the battery pack in the vehicle's high-voltage system, and the other end of the positive contactor is connected to the load.

6. The system according to claim 5, characterized in that, The vehicle high-voltage system further includes: a third resistor network, which includes an eighth resistor and a ninth resistor. One end of the eighth resistor is connected to one end of the positive contactor through a fuse unit, and the other end of the eighth resistor is connected to one end of the ninth resistor. The other end of the ninth resistor is connected to one end of the negative contactor. The control device is also used to: collect the voltage at the second voltage sampling point, and determine the total voltage of the battery pack based on the voltage at the second voltage sampling point, wherein the second voltage sampling point is the node between the eighth resistor and the ninth resistor.

7. The system according to claim 6, characterized in that, The vehicle high-voltage system further includes: a fourth resistor network, which includes a tenth resistor and an eleventh resistor. One end of the tenth resistor is connected to one end of the positive contactor, the other end of the tenth resistor is connected to one end of the eleventh resistor, and the other end of the eleventh resistor is connected to one end of the negative contactor. The control device is further configured to: acquire the voltage at the third voltage sampling point and compare the voltage at the third voltage sampling point with the voltage at the second voltage sampling point; if the voltage at the third voltage sampling point is not equal to the voltage at the second voltage sampling point, then determine that the fuse unit has failed, wherein the third voltage sampling point is the node between the tenth resistor and the eleventh resistor.

8. The system according to claim 6, characterized in that, The vehicle high-voltage system further includes: a fifth resistor network, which includes a twelfth resistor and a thirteenth resistor, one end of the twelfth resistor being connected to the other end of the positive contactor, the other end of the twelfth resistor being connected to one end of the thirteenth resistor, and the other end of the thirteenth resistor being connected to one end of the negative contactor; The control device is further configured to: acquire the voltage at the fourth voltage sampling point and compare the voltage at the fourth voltage sampling point with the voltage at the second voltage sampling point; if the voltage at the fourth voltage sampling point is equal to the voltage at the second voltage sampling point, then determine that the positive contactor is closed, wherein the fourth voltage sampling point is the node between the twelfth resistor and the thirteenth resistor.

9. The system according to claim 8, characterized in that, The control device is also used for: When the vehicle high-voltage system is in the power-on initialization phase, if the voltage at the second voltage sampling point is within a third preset range when the positive contactor is disconnected, and the absolute value of the difference between the voltage at the fourth voltage sampling point and the voltage at the second voltage sampling point is less than or equal to the first voltage threshold during the third preset time period, then it is determined that the positive contactor has a contact sticking fault. The third preset range is determined based on the maximum and minimum voltages of the battery pack in the vehicle high-voltage system. When the vehicle high-voltage system is in the power-on phase, if the voltage at the second voltage sampling point is within the third preset range when the positive contactor is closed, and the absolute value of the difference between the voltage at the fourth voltage sampling point and the voltage at the second voltage sampling point is greater than or equal to the second voltage threshold during the third preset time period, then it is determined that the positive contactor has an open circuit fault. When the vehicle's high-voltage system is in the power-off phase, and when the positive contactor is disconnected, if the voltage at the second voltage sampling point is within the third preset range, and the absolute value of the difference between the voltage at the fourth voltage sampling point and the voltage at the second voltage sampling point is less than or equal to the first voltage threshold during the fourth preset time period, then it is determined that the positive contactor has a contact sticking fault, wherein the fourth preset time period is longer than the third preset time period.

10. A method for diagnosing faults in high-voltage contactors of electric vehicles, characterized in that, The control device applied to the electric vehicle high-voltage contactor fault diagnosis system according to any one of claims 1-9, the method comprising: Based on the state of each switch in the insulation detection module, the voltage at the first voltage sampling point is collected; Based on the voltage at the first voltage sampling point and the power supply voltage, fault diagnosis is performed on the negative contactor to obtain the fault diagnosis result of the negative contactor.

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