System and method for diagnosing poor contact fault of connector terminal and vehicle

Abstract

The invention provides a connector terminal poor contact fault diagnosis system comprising a signal acquisition module used for acquiring a voltage drop signal generated when a current flows through a connector terminal to be diagnosed; the signal amplification module is used for amplifying the voltage drop signal into a diagnosis voltage signal; the control module is used for carrying out analog-to-digital conversion and fault judgment on the diagnosis voltage signal; the protection module is used for quickly cutting off the output of a power switch connected to the connector terminal to be diagnosed when a serious fault is diagnosed; and the early warning information sending module is used for sending early warning information when the early fault is diagnosed. The invention further discloses a corresponding method and a vehicle. By implementing the method, the diagnosis and early warning of the early fault of the large-current terminal and the hard protection of the serious fault can be quickly realized, and the safety and reliability of the whole vehicle can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive fault diagnosis, and particularly to a diagnosis system, method and vehicle for poor contact faults of connector terminals. Background Art

[0002] When driving power loads such as automotive water pumps, windshield wipers, window motors, and heating pads, the controller connector needs to use high-current terminals as the physical medium for current transmission. During the use of high-current connector terminals, poor contact faults are likely to be caused due to poor manufacturing, oxidation corrosion, improper operation during installation, abnormal vibration, etc., resulting in a significant increase in the power consumption and heat generation of the terminals. In some extreme cases, it will cause the connector terminals and wiring harness to overheat and burn out, and even cause the vehicle to catch fire, resulting in huge economic losses.

[0003] Power loads such as automotive water pumps, windshield wipers, window motors, and heating pads need to be controlled and driven through power switches (high-side switches, half-bridge drivers, or relays). As Figure 1 shown, it is a schematic diagram of the connection principle of a power switch using a connector to a power load in the prior art; among them, in a typical drive circuit of a power load, the control chip controls the power switch to conduct, and the current flows along the path indicated by the red arrow. A large current will flow through the power terminal, load positive terminal, load negative terminal, and ground terminal of the controller connector.

[0004] The male and female terminals of the connector are connected by contact, and the terminals have a certain contact impedance (usually from a few milliohms to dozens of milliohms). When a large current flows through the connector terminals, there will be a certain power consumption and heat generation. The formula for calculating the heating power of the connector terminals is as follows:

[0005] P t =I t *I t * Rt

[0006] Where P t is the heating power consumption of the connector terminals, I t is the current flowing through the connector terminals, and R t is the contact impedance between the male and female terminals of the connector.

[0007] Under normal circumstances, the contact impedance of the connector terminals is small, and even if a large current flows through, the heat generation of the terminals is limited. However, due to reasons such as poor terminal manufacturing, oxidation corrosion, improper operation during installation, and abnormal vibration, the effective contact area between the male and female terminals of the connector terminals will decrease, the contact impedance will increase significantly, the power consumption and heat generation of the current flowing through the terminals will increase significantly, and in some extreme cases, it will cause the connector terminals and wiring harness to overheat and burn out.

[0008] Under normal circumstances, assuming that the current flowing through the contact terminals is It = 10 A, the contact impedance R of the connector terminal t_nom = 10 mΩ, the heating power P of the connector terminal t_nom = I t * I t * R t_nom = 10 * 10 * 0.01 Ω = 1 W;

[0009] Assume that the contact impedance of the connector terminal becomes R t_abn = 50 mΩ, and still a current of 10 A flows through. The heating power of the connector increases to P t_abn = I t * I t * R t_abn = 10 * 10 * 0.05 = 5 W;

[0010] Because the heating power of the connector increases significantly, the connector terminal is easily burned out, and even causes the vehicle to catch fire, resulting in huge economic losses. In actual applications, in some vehicle models, the connector is overheated and burned out due to poor contact between the male and female terminals.

[0011] In the prior art, a solution for online diagnosis and monitoring of connectors using Hall sensors and temperature sensors has emerged. However, there are still some deficiencies in the existing solution: First, using Hall sensors and temperature sensors to detect problems such as poor contact of connectors has a high cost. At the same time, it is also difficult to install and arrange Hall sensors or temperature sensors for small-sized contact parts. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a diagnosis system, method and vehicle for poor contact faults of connector terminals, which can detect faults at the large-current end of the connector in advance and protect the circuit when serious faults occur, thereby improving vehicle safety.

[0013] To solve the above technical problem, as one aspect of the present invention, there is provided a diagnosis system for poor contact faults of connector terminals, which includes:

[0014] A signal acquisition module, configured to acquire the voltage drop signal generated when a current flows through the connector terminal to be diagnosed;

[0015] A signal amplification module, connected to the signal acquisition module, configured to amplify the voltage drop signal into a diagnostic voltage signal;

[0016] A control module, connected to the signal amplification module, configured to perform analog-to-digital conversion and fault judgment on the diagnostic voltage signal; if the diagnostic voltage signal exceeds the first threshold, it is diagnosed as an early fault, and if the diagnostic voltage signal continuously exceeds the second threshold, it is diagnosed as a serious fault;

[0017] A protection module, connected to the control module, is configured to quickly cut off the output of the power switch connected to the plug-in terminal to be diagnosed when a severe fault is diagnosed.

[0018] An early warning information sending module, connected to the control module, is configured to send early warning information when an early fault is diagnosed.

[0019] Wherein, the signal acquisition module includes a feedback wire, one end of the feedback wire is connected to the output end of the plug-in to be diagnosed, and the other end is connected to the negative input end of the signal amplification module through a small current terminal; and the positive input end of the signal amplification module is connected to the input end of the plug-in to be diagnosed.

[0020] The signal amplification module includes an operational amplifier chip and peripheral passive components, and is configured to amplify the voltage drop signal by 5 to 20 times.

[0021] Wherein, the control module includes a control chip MCU / SOC, and the control chip realizes fault judgment in the following manner:

[0022] Perform analog-to-digital conversion on the diagnostic voltage signal according to a preset impedance threshold;

[0023] If the diagnostic voltage signal exceeds the first threshold, an early fault warning is sent through the early warning information sending module;

[0024] If the diagnostic voltage signal exceeds the second threshold, the protection module is triggered to perform hard protection.

[0025] Wherein, the protection module includes a comparator chip and a delay capacitor. When the diagnostic voltage signal exceeds a preset second threshold, the comparator chip outputs a low-level signal, quickly pulls down the power switch control pin, and shuts off the output current; the delay capacitor is used to delay the restoration of the power switch output after the protection state is released.

[0026] Wherein, the system further includes a power supply module, configured to provide a stable low-voltage power supply for the control module, the signal amplification module, and the protection module.

[0027] Correspondingly, as another aspect of the present invention, a method for diagnosing a poor contact fault of a plug-in terminal is further provided, which includes the following steps:

[0028] Collect the voltage drop signal generated by the plug-in terminal to be diagnosed when current flows through it through a feedback wire;

[0029] Amplify the voltage drop signal through a signal amplification circuit to obtain a diagnostic voltage signal;

[0030] Transmit the diagnostic voltage signal to the control chip, and the control chip performs analog-to-digital conversion and fault judgment on the diagnostic voltage signal according to a preset impedance threshold; if the diagnostic voltage signal exceeds the first threshold, it is diagnosed as an early fault, and if the diagnostic voltage signal continuously exceeds the second threshold, it is diagnosed as a serious fault;

[0031] When an early fault is diagnosed, an early fault warning is sent through the vehicle communication network; when a serious fault is diagnosed, the protection circuit is triggered to quickly cut off the output of the power switch connected to the terminal of the connector to be diagnosed.

[0032] Wherein, in the fault diagnosis step, the control chip calculates the contact impedance of the connector terminal according to the following formula:

[0033] R t =I t *V t

[0034] Wherein, V t is the voltage drop signal, and I t is the current flowing through the terminal;

[0035] The preset impedance threshold includes an early fault threshold and a serious fault threshold, corresponding to the first threshold and the second threshold respectively.

[0036] Wherein, in the protection circuit, there are provided:

[0037] A comparator, when the diagnostic voltage signal exceeds the second threshold, the comparator outputs a low-level signal to quickly pull down the power switch control pin and turn off the output current; and

[0038] A delay capacitor is used to delay the recovery of the power switch output after the protection state is released.

[0039] Wherein, the second threshold is determined by any of the following methods:

[0040] Using the theoretical deduction method: Calculate the maximum safe impedance according to the maximum allowable temperature rise of the connector terminal and convert it into a voltage threshold; or

[0041] Using the experimental calibration method: By increasing the contact impedance of the connector terminal, monitor the diagnostic voltage value when the terminal temperature reaches the dangerous temperature as the second threshold.

[0042] Correspondingly, as another aspect of the present invention, a vehicle is further provided, in which the aforementioned system is deployed.

[0043] Implementing the embodiments of the present invention has the following beneficial effects:

[0044] The present invention provides a diagnostic system, method and vehicle for the fault of poor contact of connector terminals. By adopting a signal acquisition module, a signal amplification module, a protection module, a warning information sending module, etc., it is possible to diagnose the early fault of poor contact of connector terminals and give an alarm. At the same time, it is possible to perform hard protection on serious contact terminal faults to avoid the terminals and wire harnesses from burning. The safety of the corresponding circuit is improved, thereby improving the safety of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still belongs to the scope of the present invention;

[0046] Figure 1 It is a schematic diagram of the connection principle of a power switch using a connector to a power load in the prior art;

[0047] Figure 2 It is a schematic structural diagram of an embodiment of a diagnostic system for the fault of poor contact of connector terminals provided by the present invention;

[0048] Figure 3 It is a schematic diagram of the specific application environment of the system provided by the present invention;

[0049] Figure 4 It is the waveform diagram of the hard protection working process V ctl_SW involved in the system provided by the present invention;

[0050] Figure 5 It is a schematic diagram of the main process of an embodiment of a diagnostic method for the fault of poor contact of connector terminals provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings.

[0052] As Figure 2 shown, it shows a schematic structural diagram of an embodiment of a diagnostic system for the fault of poor contact of connector terminals provided by the present invention; combined with Figures 3 to 4 shown, in this embodiment, the diagnostic system 1 for the fault of poor contact of connector terminals at least includes:

[0053] A signal acquisition module 10, configured to acquire the voltage drop signal generated when the current flows through the connector terminal to be diagnosed;

[0054] In a specific example, the signal acquisition module 10 includes a feedback line. One end of the feedback line is connected to the output end of the connector to be diagnosed, and the other end is connected to the negative input end of the signal amplification module 11 through a small current terminal; and the positive input end of the signal amplification module 11 is connected to the input end of the connector to be diagnosed;

[0055] The signal amplification module 11 is connected to the signal acquisition module 10 and is used to amplify the voltage drop signal into a diagnostic voltage signal;

[0056] In a specific example, the signal amplification module 11 includes an operational amplifier chip and peripheral passive components, and is used to amplify the voltage drop signal by 5 to 20 times.

[0057] The control module 12 is connected to the signal amplification module 10 and is used to perform analog-to-digital conversion and fault judgment on the diagnostic voltage signal; if the diagnostic voltage signal exceeds the first threshold, it is diagnosed as an early fault, and if the diagnostic voltage signal continuously exceeds the second threshold, it is diagnosed as a serious fault;

[0058] In a specific example, the control module 12 includes a control chip MCU / SOC, and the control chip realizes fault judgment in the following manner:

[0059] Perform analog-to-digital conversion on the diagnostic voltage signal according to a preset impedance threshold;

[0060] If the diagnostic voltage signal exceeds the first threshold, an early fault warning is sent through the warning information sending module 14;

[0061] If the diagnostic voltage signal exceeds the second threshold, the protection module 13 is triggered to perform hard protection.

[0062] The protection module 13 is connected to the control module 12 and is used to quickly cut off the output of the power switch connected to the terminal of the connector to be diagnosed when a serious fault is diagnosed;

[0063] Specifically, the protection module 13 includes a comparator chip and a delay capacitor. When the diagnostic voltage signal exceeds the preset second threshold, the comparator chip outputs a low-level signal, quickly pulls down the power switch control pin, and turns off the output current; the delay capacitor is used to delay the recovery of the power switch output after the protection state is released.

[0064] The warning information sending module 14 is connected to the control module 12 and is used to send warning information when an early fault is diagnosed.

[0065] The power supply module 15 is used to provide a stable low-voltage power supply for the control module 14, the signal amplification module 11, and the protection module 13.

[0066] For a further understanding of the present invention, the following is an explanation in conjunction with the Figure 3 specific application environment therein as follows.

[0067] In a specific application example, the application environment of the system provided by the present invention involves the following components: ① a control chip, namely a microcontroller unit (MCU) or a system on chip (SOC); ② a power switch; ③ a power load (motor, valve, heating pad); ④ a power supply module; ⑤ a connector (high-current terminal); ⑥ a connector (low-current terminal); ⑦ a feedback wire; ⑧ a signal amplification circuit; ⑨ a protection circuit; and ⑩ an MCU control signal transmission and detection network.

[0068] Among them, the control chip MCU / SOC is generally a semiconductor chip with arithmetic and control functions, and the functions it realizes are: controlling the power switch to turn on and off, and performing analog-to-digital conversion and fault judgment on the impedance diagnostic signal of the connector terminal;

[0069] The power switch can be a high-side switch and a half-bridge drive chip, or a relay, and its main function is to control the load to turn on and off;

[0070] The power load is the motor, valve, heating pad, etc. that need to be driven;

[0071] The power supply module can be a DC-DC converter or a low dropout regulator (LDO), which provides a stable low-voltage power supply for the MCU and the power chip;

[0072] The connector (high-current terminal) includes a male terminal at the controller connector end and a female terminal of the wire harness sheath. This terminal serves as a physical relay medium for driving current transmission, connecting the PCB circuit board and the wire, and it is the connector terminal to be diagnosed in the above text;

[0073] The connector - low-current terminal includes a male terminal at the controller connector end and a female terminal of the wire harness sheath. It is a physical relay medium for diagnostic signal transmission, connecting the PCB circuit board and the wire. Since only signals need to be transmitted, terminals with a very small size can be selected;

[0074] The feedback wire is a feedback wire for the terminal impedance diagnostic signal. Since only signals need to be transmitted, a wire harness with the smallest wire diameter can be used;

[0075] The signal amplification circuit includes an operational amplifier chip and peripheral passive components (resistors, capacitors, etc.), and realizes the amplification of the diagnostic feedback signal; it realizes the function of the signal amplification module in this application;

[0076] The protection circuit includes a comparator chip and peripheral passive components (resistors, capacitors, etc.), which monitor the amplified diagnostic feedback signal. If there is an obvious abnormality, it quickly cuts off the output of the power chip to protect the connector terminals and wires. It realizes the function of the protection module in the present invention;

[0077] The MCU controls the signal transmission and detection network, which is used for the signal transmission of the MCU to control the power switch and the real-time detection of the control signal by the MCU. It realizes the function of the communication module in the present invention.

[0078] It can be understood that the contact impedance of the plug-in terminal is R t , and the current I t flowing through it will generate a voltage drop V t , and the calculation formula of V t is as follows:

[0079] V t = I t * R t .

[0080] The positive terminal PCB trace of the signal amplification circuit is pulled out near the large-current terminal of the connector. When making the wire harness, the feedback wire is crimped into the large-current terminal. The voltage drops of V t+ and V t- to the positive and negative poles of the signal amplifier circuit are very small, and the differential-mode voltage V t_in at the front end of the signal amplification circuit is approximately equal to V t ;

[0081] After being amplified 5 to 20 times by the signal amplification circuit, the diagnostic voltage V dig is obtained. The V dig voltage is output to the ADC function pin of the MCU for the diagnosis and early warning of the early faults of the connector terminal. The V dig voltage is also output to the negative terminal of the comparator of the protection circuit to perform hard protection on the serious faults where the contact impedance of the connector terminal has increased significantly and reached the point of overheating and burning the terminal and wire harness, avoiding the risks of burning and catching fire.

[0082] The principle of the diagnosis and early warning of the early faults involved in the present invention is specifically as follows: The MCU performs analog-to-digital conversion on V dig to measure the amplitude of the voltage, and the early faults of poor contact of the connector can be judged according to V dig . For example, the normal contact impedance range of a certain large-current terminal is 5 to 10 mΩ, the rated current flowing through the terminal is 10 A, and the amplification factor of the signal amplification circuit is designed to be 10 times. The maximum value of the voltage drop V t of the connector terminal under normal conditions is 1 V. If the MCU detects that the V dig voltage exceeds 1.5 to 2 times V t, it can be considered that the terminal has an early failure, and an alarm message can be sent through the vehicle communication network (CAN bus, LIN bus, Ethernet, etc.), or the fault code can be stored in the Flash of the ECU. When the user goes to the 4S store for maintenance next time, the staff of the 4S store reads the fault through ODB and focuses on detecting and maintaining the connector terminal.

[0083] The principle of the hard protection involved in the present invention: V dig When the voltage is greater than the positive terminal reference voltage of the protection circuit comparator, the comparator output is pulled low, quickly pulling low the power switch control pin to turn off the output current. When inductive loads such as motors start, there is a certain transient impact current, which is much larger than the rated current. Therefore, filter capacitors C2 and C3 are added at the front end of the input of the signal amplification current operational amplifier, and filter capacitor C4 is added at the back end to avoid misoperation of the protection circuit and affect the normal function. Because after the protection circuit turns off the power switch, the current of the large-current terminal of the connector will also be turned off, V t and V dig will both become 0V, and the comparator output will be pulled high. Therefore, a delay capacitor C1 is added to the comparator output terminal, so that the power switch can be quickly turned off and delayed to turn on in the abnormal state of the large-current terminal of the connector. The MCU can read the PWM signal entering the protection state through the voltage V ctl_FB fed back by the resistor R4, and combined with the voltage value of V dig read by the MCU. If it is diagnosed that V ctl_SW has an abnormal situation more than 20 to 50 times, it indicates that the connector terminal has an irreparable fault. The MCU turns off the V ctl output and records the fault code. The waveform diagram of the working process of the hard protection V ctl_SW can be seen in Figure 4 as shown.

[0084] In the present invention, when the large-current terminal of the connector has a serious fault, it enters the working voltage of the hard protection. In practical applications, the positive terminal reference voltage V ref of the comparator in the protection circuit can be determined by the following two methods.

[0085] Method 1, theoretical calculation method, the process is as follows:

[0086] Connect the connector, wire harness and load, and install a thermocouple near the outlet of the terminal of the connector to measure the temperature of the connector terminal;

[0087] Calibrate the thermocouple and record the ambient temperature T1 when the large-current terminal of the connector has no current passing through;

[0088] Apply the rated current to the large-current terminal of the connector to be tested. After working for a period of time until the temperature of the thermocouple is stable, record the temperature T2 of the terminal and the temperature rise ΔT of the terminal _Sn= T2 - T1;

[0089] Replace the test sample and repeat the above three steps. Test a predetermined number (e.g., 20) of samples, and take the maximum value ΔT of the temperature rise ΔT_Sn _Sn_max ;

[0090] Assume the maximum allowable temperature rise ΔT of the connector terminal _max , it can be generally considered that the maximum safe impedance that the connector can allow is R t_saf = 0.7 - 0.8 * R t_nom *ΔT _max / ΔT _Sn_max , where R t_nom is the rated maximum impedance, and calculate the positive terminal reference voltage V of the comparator according to R t_saf . ref .

[0091] Method 2, test calibration method:

[0092] Determined according to test calibration, and the process is as follows:

[0093] Process the male terminal of the connector by mechanical means to reduce the effective contact area and increase the contact impedance to N times the maximum rated impedance;

[0094] Place the test sample in a temperature environment, connect the wire harness and the load, and add a thermocouple near the outlet of this terminal of the connector to measure the temperature of the connector terminal;

[0095] Make the power circuit pass through the rated current, run for a period of time, and monitor the temperature of the terminal;

[0096] Repeat the above three steps, increasing the contact impedance of the connector terminal (for example, increasing in multiples of 1.5 times, 2 times, 2.25 times, 2.5 times, 3 times, 3.25 times the maximum rated impedance) until the temperature of the terminal in the previous step reaches the dangerous temperature, and the theoretical value of V corresponding to this contact impedance value is used as the positive terminal reference voltage. dig .

[0097] In addition, in the present invention, the pictures and text are described by taking the negative terminal of the load as an example. The system of the present invention can also be applied to the diagnosis of poor contact faults of other high - current connector terminals. These other high - current connector terminals can be, for example, the positive terminal of the load, the power supply terminal, the ground terminal, etc. The principle is the same as that described above and will not be elaborated here.

[0098] As Figure 5 shown, it shows the main flow diagram of an embodiment of a method for diagnosing poor contact faults of a connector terminal provided by the present invention. In this embodiment, the method at least includes the following steps:

[0099] Step S10: Collect the voltage drop signal generated when current flows through the connector terminal to be diagnosed via a feedback line;

[0100] Step S11: Amplify the voltage drop signal through a signal amplification circuit to obtain a diagnostic voltage signal;

[0101] Step S12: Transmit the diagnostic voltage signal to a control chip, and the control chip performs analog-to-digital conversion and fault judgment on the diagnostic voltage signal according to a preset impedance threshold; if the diagnostic voltage signal exceeds the first threshold, it is diagnosed as an early fault, and if the diagnostic voltage signal continuously exceeds the second threshold, it is diagnosed as a serious fault;

[0102] Specifically, in the fault diagnosis step, the control chip calculates the contact impedance of the connector terminal according to the following formula:

[0103] R t =I t *V t

[0104] where V t is the voltage drop signal, and I t is the current flowing through the terminal;

[0105] The preset impedance threshold includes an early fault threshold and a serious fault threshold, corresponding to the first threshold and the second threshold respectively.

[0106] Step S13: When an early fault is diagnosed, send an early fault warning through the vehicle communication network; when a serious fault is diagnosed, trigger a protection circuit to quickly cut off the output of the power switch connected to the connector terminal to be diagnosed.

[0107] Specifically, in the protection circuit, there are:

[0108] A comparator. When the diagnostic voltage signal exceeds the second threshold, the comparator outputs a low-level signal to quickly pull down the power switch control pin and turn off the output current; and

[0109] A delay capacitor, which is used to delay the restoration of the power switch output after the protection state is released.

[0110] Among them, the second threshold is determined by any of the following methods:

[0111] Using the theoretical calculation method: Calculate the maximum safe impedance according to the maximum allowable temperature rise of the connector terminal and convert it into a voltage threshold; or

[0112] Using the experimental calibration method: By increasing the contact impedance of the connector terminal, monitor the diagnostic voltage value when the terminal temperature reaches the dangerous temperature as the second threshold.

[0113] For more details, reference may be made to and in combination with the foregoing description of Figures 2 to 5 which will not be elaborated herein.

[0114] As another aspect of the present invention, a vehicle is further provided, in which a system as described in Figures 2 to 5 is deployed. For more details, reference may be made to and in combination with the foregoing description of Figures 2 to 5 which will not be elaborated herein.

[0115] Implementing the embodiments of the present invention has the following beneficial effects:

[0116] The present invention provides a diagnostic system, method and vehicle for poor contact faults of connector terminals. By adopting a signal acquisition module, a signal amplification module, a protection module, a warning information sending module, etc., early faults of poor contact of connector terminals can be diagnosed and an alarm can be given. At the same time, hard protection can be carried out on serious contact terminal faults to avoid burning of terminals and wire harnesses. The safety of the corresponding circuit is improved, thereby improving the safety of the vehicle.

[0117] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0118] The foregoing disclosure is only a preferred embodiment of the present invention, and of course, it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A diagnostic system for the fault of poor contact of a connector terminal, characterized in that, Comprising: A signal acquisition module, configured to acquire the voltage drop signal generated when a current flows through the connector terminal to be diagnosed; A signal amplification module, connected to the signal acquisition module, and configured to amplify the voltage drop signal into a diagnostic voltage signal; A control module, connected to the signal amplification module, and configured to perform analog-to-digital conversion and fault judgment on the diagnostic voltage signal; if the diagnostic voltage signal exceeds a first threshold, it is diagnosed as an early fault, and if the diagnostic voltage signal continuously exceeds a second threshold, it is diagnosed as a serious fault; A protection module, connected to the control module, and configured to quickly cut off the output of the power switch connected to the connector terminal to be diagnosed when a serious fault is diagnosed; An early warning information sending module, connected to the control module, and configured to send early warning information when an early fault is diagnosed.

2. The system according to claim 1, wherein Wherein: The signal acquisition module includes a feedback wire, one end of the feedback wire is connected to the output end of the connector to be diagnosed, and the other end is connected to the negative input end of the signal amplification module through a small current terminal; and the positive input end of the signal amplification module is connected to the input end of the connector to be diagnosed; The signal amplification module includes an operational amplifier chip and peripheral passive components, and is configured to amplify the voltage drop signal by 5 to 20 times.

3. The system according to claim 2, wherein The control module includes a control chip MCU / SOC, and the control chip realizes fault judgment in the following manner: Performing analog-to-digital conversion on the diagnostic voltage signal according to a preset impedance threshold; If the diagnostic voltage signal exceeds the first threshold, an early fault warning is sent through the early warning information sending module; If the diagnostic voltage signal exceeds the second threshold, the protection module is triggered for hard protection.

4. The system according to claim 3, wherein Wherein: The protection module includes a comparator chip and a delay capacitor. When the diagnostic voltage signal exceeds the preset second threshold, the comparator chip outputs a low-level signal, quickly pulls down the power switch control pin, and shuts off the output current; the delay capacitor is used to delay the restoration of the power switch output after the protection state is released.

5. The system according to claim 4, wherein The system further includes a power supply module, configured to provide a stable low-voltage power supply for the control module, the signal amplification module, and the protection module.

6. A diagnostic method for poor contact faults of connector terminals, characterized in that, Including the following steps: Acquiring the voltage drop signal generated when a current flows through the connector terminal to be diagnosed through a feedback wire; Amplifying the voltage drop signal through a signal amplification circuit to obtain a diagnostic voltage signal; Transmitting the diagnostic voltage signal to the control chip, and the control chip performs analog-to-digital conversion and fault judgment on the diagnostic voltage signal according to a preset impedance threshold; if the diagnostic voltage signal exceeds the first threshold, it is diagnosed as an early fault, and if the diagnostic voltage signal continuously exceeds the second threshold, it is diagnosed as a serious fault; When an early fault is diagnosed, an early fault warning is sent through the vehicle communication network; when a serious fault is diagnosed, the protection circuit is triggered to quickly cut off the output of the power switch connected to the connector terminal to be diagnosed.

7. The diagnostic method according to claim 6, wherein In the fault diagnosis step, the control chip calculates the contact impedance of the connector terminal according to the following formula: R t = I t * V t Among them, V t is the pressure drop signal, and I t is the current flowing through the terminal; The preset impedance threshold includes an early fault threshold and a serious fault threshold, corresponding to the first threshold and the second threshold respectively.

8. The diagnostic method according to claim 7, characterized in that In the protection circuit, there is provided: A comparator that outputs a low-level signal when the diagnostic voltage signal exceeds the second threshold, quickly pulling down the power switch control pin to turn off the output current; and A delay capacitor for delaying the recovery of the power switch output after the protection state is released.

9. The diagnostic method according to claim 8, characterized in that, The second threshold is determined by any of the following methods: Using the theoretical calculation method: calculating the maximum safe impedance based on the maximum allowable temperature rise of the connector terminal and converting it into a voltage threshold; Or Using the test calibration method: by increasing the contact impedance of the connector terminal, monitoring the diagnostic voltage value when the terminal temperature reaches the dangerous temperature as the second threshold.

10. A vehicle, characterized in that, Wherein a system as described in any one of claims 1 to 5 is deployed.

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