Failure diagnosis system, method, and apparatus for electric vehicle insulation detection function

Abstract

The embodiment of the application relates to the technical field of electric vehicles, and discloses a failure diagnosis system, method and equipment for an insulation detection function of an electric vehicle, the system comprising a diagnosis equipment and a server in communication connection, wherein the diagnosis equipment comprises a direct current bus, N detection resistor groups and an equipment ground, the N detection resistor groups one-to-one corresponding to N resistance value intervals, each positive electrode detection resistor being connected to a positive electrode end of the direct current bus and the equipment ground through a first switch, and each negative electrode detection resistor being connected to a negative electrode end of the direct current bus and the equipment ground through a second switch. The diagnosis system can determine whether the detection of the electric vehicle on external resistance is accurate, and further determine whether the insulation detection function is normal or fails. Based on the one-to-one correspondence between the N detection resistor groups and the N resistance value intervals, in multiple diagnoses, the diagnosis system can detect the measurement accuracy of the electric vehicle on the resistance of each resistance value interval, so that the diagnosis result is more accurate.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the technical field of electric vehicles, and in particular to a system, method and device for diagnosing failure of insulation detection function of an electric vehicle. BACKGROUND

[0002] Electric vehicles use electric energy to solve the problems of energy consumption and greenhouse gas emissions caused by traditional oil vehicles, achieve energy saving and emission reduction, and environmental protection and sustainable development. In order to meet the driving power (P=UI) required by electric vehicles, electric vehicles generally adopt high-voltage platform design to reduce working current, reduce heat and loss, etc. At present, the working voltage of most passenger vehicles is 400V, and some high-end vehicles have been launched with 800V working voltage, and the working voltage of some large and heavy electric vehicles has reached more than 1000V.

[0003] Under such a high-voltage system, the insulation between the power battery of the electric vehicle and the external environment is very important. If the insulation of the power battery of the electric vehicle is poor, it will pose a great threat to the personal safety of the user. At present, electric vehicles have insulation detection function, that is, mainly rely on the battery management system (BATTERY MANAGEMENT SYSTEM, BMS) of the battery to detect the insulation of the positive electrode to ground and the negative electrode to ground. However, if the insulation detection function fails, it may cause fatal electric shock risk to the driver and passengers. SUMMARY

[0004] The technical problem solved by the embodiments of the present application is to provide a system, method and device for diagnosing failure of insulation detection function of an electric vehicle, which can accurately diagnose whether the insulation detection function of the electric vehicle is failed, find the function failure problem in time, and improve the safety.

[0005] To solve the above technical problems, in a first aspect, the embodiments of the present application provide a failure diagnosis system for an insulation detection function of an electric vehicle, comprising a diagnosis device and a server connected in communication, the diagnosis device comprising a direct current bus, N detection resistor groups, and a device ground, each of the N detection resistor groups corresponding to one of N resistance value intervals, each of the detection resistor groups comprising a positive detection resistor and a negative detection resistor, the positive detection resistor being connected to a positive terminal of the direct current bus and the device ground through a first switch, and the negative detection resistor being connected to a negative terminal of the direct current bus and the device ground through a second switch, wherein N is an integer greater than or equal to 1; the positive terminal of the direct current bus is used to connect a positive electrode of a battery of the electric vehicle, and the negative terminal of the direct current bus is used to connect a negative electrode of the battery of the electric vehicle, and the diagnosis device is further used to be connected in communication with the electric vehicle; the diagnosis device controls one of the positive detection resistor and the negative detection resistor to be connected to the closed switch each time, and the switch is one of the first switch and the second switch;

[0006] The diagnosis device reads a measured resistance value of the detection resistor fed back by the electric vehicle after each time the diagnosis device controls the switch to be closed;

[0007] The diagnosis device determines a measurement deviation of the electric vehicle for the detection resistor according to the measured resistance value of the detection resistor and an actual resistance value of the detection resistor;

[0008] The diagnosis device uploads the measurement deviation to the server, and the server determines that the insulation detection function of the electric vehicle is normal or fails according to at least one measurement deviation of the electric vehicle for the detection resistor.

[0009] In some embodiments, the diagnosis device controls the first switch and the second switch corresponding to one of the N detection resistor groups to be closed in sequence, and then controls the first switch and the second switch corresponding to the next one of the N detection resistor groups to be closed in sequence.

[0010] The diagnosis device uploads the measurement deviation corresponding to the N detection resistor groups to the server, and the server determines that the insulation detection function of the electric vehicle is normal or fails according to the measurement deviation corresponding to the N detection resistor groups.

[0011] In some embodiments, if the server detects that a target measurement deviation greater than or equal to a deviation threshold exists in the measurement deviation corresponding to the N detection resistor groups for a first preset number of times in succession, it is determined that the insulation detection function of the electric vehicle fails, and the target measurement deviation is any one of the measurement deviation corresponding to the N detection resistor groups.

[0012] In some embodiments, the diagnostic device controls the first switch and the second switch corresponding to one of the N groups of detection resistors to be closed in sequence, and then controls the first switch and the second switch corresponding to the next group of detection resistors to be closed in sequence.

[0013] After the diagnostic device obtains at least one measurement deviation corresponding to one group of detection resistors each time, the diagnostic device uploads the at least one measurement deviation corresponding to the group of detection resistors to the server, and the server determines whether the insulation detection function of the electric vehicle is normal or invalid according to the at least one measurement deviation corresponding to the group of detection resistors.

[0014] In some embodiments, the diagnostic device controls the first switch and the second switch corresponding to the group of detection resistors with the smallest resistance interval to be closed in sequence, and then reads feedback information of the electric vehicle.

[0015] The diagnostic device determines whether the insulation detection function of the electric vehicle is normal or invalid according to the feedback information.

[0016] In some embodiments, the diagnostic device uploads at least one of the feedback information to the server, and the server determines whether the insulation monitoring function of the electric vehicle is normal or invalid according to the at least one feedback information.

[0017] In some embodiments, if the server detects an alarm abnormality in at least one of the feedback information for a second preset number of times in succession, it is determined that the insulation detection function of the electric vehicle is invalid.

[0018] In some embodiments, the diagnostic device further comprises a voltmeter connected between the positive terminal and the negative terminal of the DC bus.

[0019] After the diagnostic device controls the first switch and the second switch corresponding to the group of detection resistors with the smallest resistance interval to be closed in sequence, if the voltage measured by the voltmeter is 0, it is determined that the insulation detection function of the electric vehicle is normal.

[0020] In some embodiments, before the diagnostic device controls the first switch and the second switch corresponding to the group of detection resistors with the smallest resistance interval to be closed in sequence, the diagnostic device reads the voltage measured by the voltmeter, and if the voltage is the normal output voltage of the battery, it prompts the control of the closed switch to perform the diagnostic work.

[0021] In some embodiments, the system further comprises a vehicle communication interface device for communicatively connecting the diagnostic device and the electric vehicle.

[0022] To solve the above technical problems, in a second aspect, the embodiments of the present application provide a diagnostic device, comprising a direct current bus, N detection resistor groups, a device ground, a processor and a communication module;

[0023] Each of the N detection resistor groups corresponds to one of N resistance value intervals, each of the detection resistor groups comprises a positive detection resistor and a negative detection resistor, the positive detection resistor connects a positive terminal of the direct current bus and the device ground through a first switch, and the negative detection resistor connects a negative terminal of the direct current bus and the device ground through a second switch, wherein N is an integer greater than or equal to 1;

[0024] The positive terminal of the direct current bus is used to connect a positive electrode of a battery of an electric vehicle, the negative terminal of the direct current bus is used to connect a negative electrode of the battery of the electric vehicle, and the communication module is used to be communicatively connected with the electric vehicle;

[0025] The processor controls any one of the positive detection resistor and the negative detection resistor to be connected with a closed switch each time, and the switch is one of the first switch and the second switch;

[0026] After the processor controls the switch to be closed each time, the communication module reads a measured resistance value of the detection resistor fed back by the electric vehicle;

[0027] The processor determines a measurement deviation of the detection resistor by the electric vehicle according to the measured resistance value of the detection resistor and an actual resistance value of the detection resistor;

[0028] The processor determines that the insulation detection function of the electric vehicle is normal or fails according to at least one measurement deviation of the detection resistor by the electric vehicle.

[0029] In some embodiments, after the processor controls the first switch and the second switch corresponding to one of the N detection resistor groups to be closed in turn, the processor controls the first switch and the second switch corresponding to the next one of the N detection resistor groups to be closed in turn;

[0030] The processor determines that the insulation detection function of the electric vehicle is normal or fails according to the measurement deviations corresponding to the N detection resistor groups.

[0031] In some embodiments, if the processor detects that a target measurement deviation greater than or equal to a deviation threshold exists in the measurement deviations corresponding to the N detection resistor groups for a first preset number of times in succession, the processor determines that the insulation detection function of the electric vehicle fails, and the target measurement deviation is any one of the measurement deviations corresponding to the N detection resistor groups.

[0032] In some embodiments, the processor controls the first switch and the second switch corresponding to one of the N groups of detection resistors to be closed in turn, and then controls the first switch and the second switch corresponding to the next one of the N groups of detection resistors to be closed in turn.

[0033] After the processor obtains at least one measurement deviation corresponding to one group of detection resistors each time, the processor determines whether the insulation detection function of the electric vehicle is normal or fails according to the at least one measurement deviation corresponding to the group of detection resistors.

[0034] In some embodiments, the processor controls the first switch and the second switch corresponding to the group of detection resistors with the smallest resistance interval to be closed in turn, and then reads feedback information of the electric vehicle.

[0035] According to the feedback information, the processor determines whether the insulation detection function of the electric vehicle is normal or fails.

[0036] In some embodiments, if the processor detects that there is an alarm abnormality in at least one of the feedback information for a second preset number of times in succession, the processor determines that the insulation detection function of the electric vehicle fails.

[0037] In some embodiments, the diagnostic device further comprises a voltmeter connected between the positive terminal and the negative terminal of the direct current bus.

[0038] After the processor controls the first switch and the second switch corresponding to the group of detection resistors with the smallest resistance interval to be closed in turn, if the voltage measured by the voltmeter is 0, the processor determines that the insulation detection function of the electric vehicle is normal.

[0039] In some embodiments, before the processor controls the first switch and the second switch corresponding to the group of detection resistors with the smallest resistance interval to be closed in turn, the communication module reads the voltage measured by the voltmeter, and if the voltage is the normal output voltage of the battery, the processor prompts to control the switch to be closed for diagnosis.

[0040] To solve the above technical problems, in a third aspect, an embodiment of the present application provides a diagnostic device, comprising a direct current bus, N groups of detection resistors, a device ground, a processor, and a communication module.

[0041] Each of the N groups of detection resistors corresponds to one of N resistance intervals, each of the N groups of detection resistors comprises a positive detection resistor and a negative detection resistor, the positive detection resistor connects the positive terminal of the direct current bus and the device ground through a first switch, the negative detection resistor connects the negative terminal of the direct current bus and the device ground through a second switch, and N is an integer greater than or equal to 1.

[0042] The positive terminal of the direct current bus is used for connecting the positive pole of the battery of the electric vehicle, the negative terminal of the direct current bus is used for connecting the negative pole of the battery of the electric vehicle, and the communication module is used for being communicatively connected with the server and the electric vehicle respectively;

[0043] The processor controls the switch connected with any one of the positive detection resistor and the negative detection resistor to be closed each time, and the switch is one of the first switch and the second switch;

[0044] After the processor controls the switch to be closed each time, the communication module reads the measured resistance value of the detection resistor fed back by the electric vehicle;

[0045] The processor determines the measurement deviation of the detection resistor according to the measured resistance value of the detection resistor and the actual resistance value of the detection resistor;

[0046] The communication module uploads the measurement deviation to the server, so that the server determines that the insulation detection function of the electric vehicle is normal or fails according to at least one measurement deviation of the detection resistor of the electric vehicle.

[0047] In some embodiments, after the processor controls the first switch and the second switch corresponding to one detection resistor group in the N detection resistor groups to be closed in turn, the processor controls the first switch and the second switch corresponding to the next detection resistor group in the N detection resistor groups to be closed in turn;

[0048] The communication module uploads the measurement deviation corresponding to the N detection resistor groups to the server, so that the server determines that the insulation detection function of the electric vehicle is normal or fails according to the measurement deviation corresponding to the N detection resistor groups.

[0049] In some embodiments, if the processor detects that a target measurement deviation greater than or equal to a deviation threshold exists in the measurement deviation corresponding to the N detection resistor groups for a first preset number of times in succession, it is determined that the insulation detection function of the electric vehicle fails, and the target measurement deviation is any one of the measurement deviation corresponding to the N detection resistor groups.

[0050] In some embodiments, after the processor controls the first switch and the second switch corresponding to one detection resistor group in the N detection resistor groups to be closed in turn, the processor controls the first switch and the second switch corresponding to the next detection resistor group in the N detection resistor groups to be closed in turn;

[0051] The communication module uploads the at least one measurement deviation corresponding to the detection resistor group to the server, so that the server determines that the insulation detection function of the electric vehicle is normal or invalid according to the at least one measurement deviation corresponding to the detection resistor group.

[0052] In some embodiments, the processor controls the first switch and the second switch corresponding to the detection resistor group with the minimum resistance interval to be closed in sequence, and reads feedback information of the electric vehicle.

[0053] The processor determines that the insulation detection function of the electric vehicle is normal or invalid according to the feedback information.

[0054] In some embodiments, the communication module uploads at least one of the feedback information to the server, so that the server determines that the insulation monitoring function of the electric vehicle is normal or invalid according to at least one of the feedback information.

[0055] In some embodiments, if the server detects that there is an alarm exception in at least one of the feedback information for a second preset number of times in succession, it is determined that the insulation detection function of the electric vehicle is invalid.

[0056] In some embodiments, the diagnostic device further comprises a voltmeter connected between the positive terminal and the negative terminal of the direct current bus.

[0057] The processor controls the first switch and the second switch corresponding to the detection resistor group with the minimum resistance interval to be closed in sequence, and if the communication module reads that the voltage measured by the voltmeter is 0, the processor determines that the insulation detection function of the electric vehicle is normal.

[0058] In some embodiments, before the processor controls the first switch and the second switch corresponding to the detection resistor group with the minimum resistance interval to be closed in sequence, the communication module reads the voltage measured by the voltmeter, and if the voltage is the normal output voltage of the battery, the processor prompts to control the switch to be closed for diagnosis.

[0059] To solve the above technical problems, in a fourth aspect, the embodiments of the present application provide a charging pile, which comprises the diagnostic device of the first aspect or the diagnostic device of the second aspect.

[0060] The beneficial effects of the embodiments of the present application: different from the prior art, the failure diagnosis system of the insulation detection function of the electric vehicle provided by the embodiments of the present application, comprising a diagnostic device and a server connected in communication, wherein the diagnostic device comprises a direct current bus, N detection resistance groups and a device ground, each detection resistance group corresponds to one of N resistance value regions, each detection resistance group comprises a positive detection resistance and a negative detection resistance, the positive detection resistance is connected to the positive terminal of the direct current bus and the device ground through a first switch, and the negative detection resistance is connected to the negative terminal of the direct current bus and the device ground through a second switch. When performing failure diagnosis, the positive terminal of the direct current bus is connected to the positive electrode of the battery of the electric vehicle, the negative terminal of the direct current bus is connected to the negative electrode of the battery of the electric vehicle, and the diagnostic device is connected in communication with the electric vehicle. The diagnostic device controls the closing of the switch connected to any one of the positive detection resistance and the negative detection resistance each time, and the switch is one of the first switch and the second switch. After the diagnostic device controls the closing of the switch each time, the measured resistance value of the detection resistance fed back by the electric vehicle is read. The diagnostic device determines the measurement deviation of the electric vehicle for the detection resistance according to the measured resistance value of the detection resistance and the actual resistance value of the detection resistance. The diagnostic device uploads the measurement deviation to the server, and the server determines whether the insulation detection function of the electric vehicle is normal or fails according to at least one measurement deviation of the electric vehicle for the detection resistance.

[0061] In this diagnosis system, the diagnostic device can accurately monitor the measurement deviation of the electric vehicle to the external resistance, and the server can determine whether the detection of the electric vehicle to the external resistance is accurate based on the measurement deviation. If the measurement is accurate, the insulation detection function is normal, and if the measurement is not accurate, the insulation detection function is failed. Based on the one-to-one correspondence between the N detection resistance groups and the N resistance value intervals, the diagnostic system can detect the measurement accuracy of the electric vehicle to the resistance of each resistance value interval in multiple diagnoses, so that the diagnosis result is more accurate. BRIEF DESCRIPTION OF DRAWINGS

[0062] One or more embodiments are illustrated by way of example in the figures that are part of this disclosure and which are illustrative, but not restrictive, of the embodiments, wherein elements having the same reference numbers designate corresponding elements and wherein the figures do not limit the present embodiments to the precise arrangements and configurations shown in the figures.

[0063] Figure 1 The structure schematic diagram of the battery management system of the battery in some embodiments of the present application;

[0064] Figure 2 The structure schematic diagram of the failure diagnosis system of the insulation detection function of the electric vehicle in some embodiments of the present application;

[0065] Figure 3 The structure schematic diagram of the diagnostic device in some embodiments of the present application. DETAILED DESCRIPTION

[0066] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but in no way limit the application. It should be noted that for those skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made. These are within the scope of protection of the application.

[0067] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described here are only used to explain the application and not to limit the application.

[0068] It should be noted that the features in the embodiments of the application can be combined with each other without conflict, and are within the scope of protection of the application. In addition, although the functional modules are divided in the device schematic diagram, and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order from the module division in the device or the order in the flowchart. In addition, the "first", "second", "third" and the like used herein do not limit the data and execution order, but only distinguish the same items or similar items with basically the same function and effect.

[0069] Unless otherwise defined, all technical and scientific terms used in the specification have the same meaning as understood by those skilled in the art to which the application belongs. The terms used in the specification of the application are only for the purpose of describing the specific embodiments and are not used to limit the application. The term "and / or" used in the specification includes any and all combinations of one or more related listed items.

[0070] In addition, the technical features involved in each embodiment of the application described below can be combined with each other as long as there is no conflict.

[0071] Before introducing the technical scheme of the application, the insulation detection function of the electric vehicle is first introduced. The insulation detection function is mainly to detect the insulation resistance value of the positive electrode to ground and the negative electrode to ground by the battery management system (BATTERY MANAGEMENT SYSTEM, BMS) provided by the battery. If the insulation resistance value of the positive electrode to ground and the negative electrode to ground is large, the insulation between the battery and the external environment is better. If the insulation resistance value of the positive electrode to ground and the negative electrode to ground is small, there is a risk of electric shock, and the battery management system needs to report a warning message and cut off the power supply output end of the battery in time. It can be understood that the power supply output end here can be the positive electrode and the negative electrode of the battery, and the positive electrode and the negative electrode are connected to the direct current bus inside the electric vehicle to supply power to the drive system.

[0072] The battery management system (BMS) is a protection and management unit of the battery. Figure 1 As shown in the figure, the battery 100 includes a battery body 10 and a battery management system 20. The battery body 10 can be a battery cell or one or more battery cell modules.

[0073] The battery management system 20 includes a voltage sampling module 21, a current sampling module 22, an insulation detection module 23, a temperature sensor 24, a controller 25, and a switching circuit 26. The voltage sampling module 21 is used to collect the voltage and passive balancing electric quantity of the battery body 10 in real time. The current sampling module 22 is used to sample the current of the battery body 10 during charging and discharging. The insulation detection module 23 is used to detect the insulation resistance between the positive electrode and the ground and between the negative electrode and the ground of the battery body 10. The greater the resistance value, the better the insulation between the positive electrode and the ground and between the negative electrode and the ground of the battery body 10, and the better the insulation between the battery and the external environment. The temperature sensor 24 is used to collect the temperature of the battery body 10 in real time.

[0074] It can be understood that the voltage sampling module 21, the current sampling module 22, and the insulation detection module 23 can be realized by existing chip modules (such as integrated circuits IC) or conventional circuits in the art, and the circuit structure of the voltage sampling module 21, the current sampling module 22, and the insulation detection module 23 will not be described in detail here. The temperature sensor 24 can be realized by existing thermal resistance or thermocouple, and the structure and principle of the temperature sensor 24 will not be described in detail here.

[0075] The voltage sampling module 21, the current sampling module 22, and the insulation detection module 23 transmit the collected data to the controller 25 (MCU). The controller 25 determines the protection measures corresponding to the abnormal states of the battery 100, such as under-voltage, over-voltage, over-current, short circuit, over-temperature, low temperature, and insulation resistance value, according to the collected data, and then controls the switching circuit 26 to selectively disconnect or conduct the connection between the battery 100 and the external device 30 (load, charger, or diagnostic device, etc.) according to the determined protection measures, in order to implement the determined protection measures.

[0076] In some insulation detection schemes known to the inventors, the vehicle end BMS insulation detection mainly includes the bridge method and the signal injection method. Among them, the bridge method is to obtain the static time from the change of the external insulation environment to the steady state of the electrical environment and the insulation resistance when the external insulation environment changes. After the external insulation environment changes to different degrees, the static time can be accurately and timely obtained and the insulation resistance is calculated, which ensures timely response to the change of the external insulation environment and avoids threatening the safety of the user. The signal injection method is that the insulation detection system selects a suitable PWM pulse signal according to the total voltage of the battery pack, injects it into the high-voltage electrical subsystem of the electric vehicle, and then collects the voltage signals on both sides of the sampling resistor to calculate the insulation resistance value of the electric vehicle.

[0077] According to the industry standard, when the insulation resistance of the positive electrode to ground or the negative electrode to ground is detected to be lower than 100Ω / V, it is determined as a serious insulation failure, and the vehicle high-voltage system (i.e. the battery) should stop output immediately and notify the driver and passengers.

[0078] However, the main factors causing poor insulation and high-voltage leakage are collision, damage, liquid leakage, moisture, corrosion, etc. These factors occur relatively slowly and have a low probability of occurrence. These factors can also cause the insulation detection function of the BMS to fail. In addition, communication failure and measurement error can also cause the insulation detection function to fail to protect or alarm normally. For example, some vehicles may not have insulation problems for several years or hundreds of thousands of kilometers of travel, and lack of detection of the vehicle insulation detection function itself. When a real high-voltage leakage hazard occurs, the system may misreport or even not report the alarm, which can cause serious casualties.

[0079] To solve the above problems, some embodiments of the present application provide a failure diagnosis system for the insulation detection function of an electric vehicle. Please refer to Figure 2 , Figure 2 The structure diagram of the failure diagnosis system for the insulation detection function of the electric vehicle in some embodiments of the present application is shown. The system includes a diagnosis device and a server connected in communication.

[0080] The server can be a local physical server, or a cloud device, such as a cloud server, a cloud host, a cloud service platform, a cloud computing platform, etc. In Figure 2 , the server is a cloud platform. The cloud platform is connected in communication with the diagnosis device through a wireless network such as 4G, 5G or WIFI. In some embodiments, the communication protocols followed by the two can be TCP / IP, NETBEUI and IPX / SPX protocols.

[0081] It can be understood that the server can be in communication connection with multiple diagnostic devices, so that the electric vehicle adopts different diagnostic devices to diagnose the insulation detection function in different places, and each diagnostic device can upload the diagnostic data to the server, and the server determines the diagnostic result based on the diagnostic data. Thus, the server can save the corresponding historical diagnostic result of the electric vehicle, which is convenient for viewing, and in addition, it is not restricted by the location of the diagnostic device, and the electric vehicle can be diagnosed at any time in a place with a diagnostic device, without the need to go to a place each time, which is more flexible.

[0082] In some embodiments, the diagnostic device in the failure diagnosis system can be a diagnostic device dedicated to a car repair point, which not only has an insulation detection function, but also can detect car faults. The user can use it to quickly read the faults in the car electric control system and display the fault information through the liquid crystal display screen to quickly find out the fault part and cause.

[0083] In some embodiments, the diagnostic device in the failure diagnosis system can be integrated in a charging pile to periodically diagnose whether the insulation detection function is effective before or after charging the electric vehicle, so as to timely find out the insulation detection function failure problem and improve the convenience and timeliness.

[0084] Specifically, please refer again to Figure 2 The diagnostic device includes a direct current bus, N detection resistor groups, and a device ground. Each detection resistor group corresponds to one of N resistance value regions, and each detection resistor group includes a positive detection resistor and a negative detection resistor. Each positive detection resistor is connected to a positive terminal of the direct current bus and the device ground through a first switch, and each negative detection resistor is connected to a negative terminal of the direct current bus and the device ground through a second switch. When performing failure diagnosis, the positive terminal of the direct current bus is connected to the positive electrode of the battery of the electric vehicle, and the negative terminal of the direct current bus is connected to the negative electrode of the battery of the electric vehicle. The device ground refers to the device shell that can be touched by the user.

[0085] N is an integer greater than or equal to 1, for example, N can be 4, then there are 4 detection resistor groups of different resistance value intervals, that is, including 4 positive detection resistors of different resistance values and 4 negative detection resistors of different resistance values. The number of first switches can be determined based on the type, for example, if the first switch is a single-pole switch, then one positive detection resistor is connected to the positive terminal of the direct current bus and the device ground through one first switch, and if the first switch is a single-pole double-throw switch, then two positive detection resistors are connected to the positive terminal of the direct current bus and the device ground through one first switch. The number of second switches can be determined based on the type, for example, if the second switch is a single-pole switch, then one negative detection resistor is connected to the positive terminal of the direct current bus and the device ground through one second switch, and if the second switch is a single-pole double-throw switch, then two negative detection resistors are connected to the positive terminal of the direct current bus and the device ground through one second switch. Figure 2Simplified shows that the positive detection resistor Rpi and the corresponding first switch Kpi in any one detection resistor group are connected between the positive terminal of the DC bus and the device ground, and the negative detection resistor Rni and the corresponding second switch Kni are connected between the negative terminal of the DC bus and the device ground.

[0086] It can be understood that when the failure diagnosis is performed, the positive terminal of the DC bus is connected to the positive electrode of the battery of the electric vehicle, the negative terminal of the DC bus is connected to the negative electrode of the battery of the electric vehicle, if the first switch Kpi is closed, it is equivalent to connecting a positive detection resistor Rpi between the positive electrode of the battery and the vehicle ground, if the second switch Kni is closed, it is equivalent to connecting a negative detection resistor Rni between the negative electrode of the battery and the vehicle ground. Here, the vehicle ground refers to the vehicle shell that can be touched by the user, and it can be understood that the vehicle ground and the device ground are both ground terminals, and the device ground can be equivalent to the vehicle ground.

[0087] It can be understood that in theory, the insulation resistance of the positive electrode to ground and the insulation resistance of the negative electrode to ground are both infinite, so as to achieve insulation protection effect. The positive detection resistor and the negative detection resistor are both smaller than the insulation resistance of the positive electrode to ground and the insulation resistance of the negative electrode to ground. Therefore, when any one switch is closed, it is equivalent to connecting a detection resistor between the battery and the vehicle ground, so that the battery is not insulated to ground. Under normal circumstances, the insulation detection module 23 of the battery management system will detect the resistance value of the battery to ground, find that the resistance value is small and the insulation is poor, and there is a risk of electric shock, then the battery management system will report an alarm information, and cut off the power supply output end of the battery in time.

[0088] It can be understood that accurate measurement of the insulation resistance of the battery to ground is the premise of triggering the insulation protection function, and the vehicle insulation detection function will trigger a serious fault when the measured system insulation resistance quantitative value is lower than 100Ω / V, and will trigger a slight alarm when the system insulation resistance quantitative value is between 100Ω / V and 500Ω / V. Here, the system insulation resistance quantitative value refers to the smaller value of the positive electrode to ground and the negative electrode to ground. It can be understood that for vehicles with different working voltages, the system insulation resistance quantitative value is also different.

[0089] In order to diagnose the detection accuracy of the battery management system (BMS) for the resistance of each resistance interval, N detection resistance groups of different resistance intervals are set (for example, N is 4) to cover 4 resistance intervals. For example, one resistance value is selected from each of the 4 resistance intervals of 0 Ω / V~100 Ω / V, 100 Ω / V~500 Ω / V, 500 Ω / V~2000 Ω / V and greater than 2000 Ω / V as the resistance value of the positive detection resistance and the negative detection resistance. As shown in Table 1, the resistance values of the 4 positive detection resistances and the 4 negative detection resistances are distributed in the 4 resistance intervals of 0 Ω / V~100 Ω / V, 100 Ω / V~500 Ω / V, 500 Ω / V~2000 Ω / V and greater than 2000 Ω / V, and for each resistance interval, the system insulation resistance quantitative value of the vehicle with different working voltages is also different. The positive detection resistance or the negative detection resistance in the same resistance interval is less than the system insulation resistance quantitative value of the different vehicles.

[0090] Table 1, resistance value setting of positive detection resistance and negative detection resistance

[0091]

[0092] Based on Figure 2 The structure of the diagnosis device is that the diagnosis device controls the closing of the switch connected to any one of the positive detection resistance and the negative detection resistance each time, and the switch is one of the first switch and the second switch. After the switch is closed, a detection resistance is connected between the battery and the vehicle ground, and the battery management system of the electric vehicle measures the resistance value of the detection resistance. Based on the communication connection between the diagnosis device and the electric vehicle, after the diagnosis device controls the closing of the switch each time, the measurement resistance value of the detection resistance fed back by the electric vehicle can be read. For example, for the positive detection resistance Rpi, after the first switch Kpi corresponding to the positive detection resistance Rpi is controlled to be closed, the insulation detection module 23 of the battery management system measures the resistance value of the positive electrode to the ground, that is, measures the resistance value of the positive detection resistance Rpi, and the measured resistance value is called the measurement resistance value Rpi_read. Therefore, the diagnosis device reads the measurement resistance value Rpi_read of the detection resistance Rpi fed back by the electric vehicle.

[0093] The diagnosis device determines the measurement deviation of the electric vehicle for the detection resistance according to the measurement resistance value of the detection resistance and the actual resistance value of the detection resistance. In some embodiments, the measurement deviation of the positive detection resistance can be calculated by the following formula:

[0094]

[0095] wherein, R pi is the i-th positive detection resistance, and R pi_read is the measurement resistance value corresponding to the i-th positive detection resistance.

[0096] Similarly, the measurement deviation of the negative electrode detection resistor is calculated by the following formula:

[0097]

[0098] wherein, R ni is the i-th negative electrode detection resistor, R ni_read is the measured resistance value corresponding to the i-th negative electrode detection resistor.

[0099] The diagnostic device uploads the measurement deviation to the server, and the server determines whether the insulation detection function of the electric vehicle is normal or invalid according to the measurement deviation of the electric vehicle for the detection resistor. If the measurement deviation is small, it means that the electric vehicle measures the resistance to ground accurately, and the insulation detection function is normal. If the measurement deviation is large, it means that the electric vehicle measures the resistance to ground inaccurately, and the insulation detection function is invalid.

[0100] It can be understood that in some embodiments, the diagnostic device can control the same detection resistor connection switch to be closed during several consecutive diagnoses, so that the server obtains at least one measurement deviation of the electric vehicle for the detection resistor, and based on the at least one measurement deviation, the insulation detection function of the electric vehicle can be accurately determined to be normal or invalid, avoiding diagnostic errors.

[0101] In some embodiments, the diagnostic device can control different detection resistor connection switches to be closed during several consecutive diagnoses, so that the server obtains the measurement deviation of the electric vehicle for multiple detection resistors. Based on the N detection resistor group corresponding to the N resistance value interval, the diagnostic system can detect the measurement accuracy of the electric vehicle for the resistors in each resistance value interval during multiple diagnoses, so that the diagnosis result of the insulation detection function is more accurate.

[0102] In some embodiments, the diagnostic device controls the first switch and the second switch corresponding to one of the N detection resistance groups to be closed in turn, and then controls the first switch and the second switch corresponding to the next detection resistance group of the N detection resistance groups to be closed in turn. Taking N=4 as an example, the first detection resistance group includes the positive detection resistance Rpl and the negative detection resistance Rnl, the second detection resistance group includes the positive detection resistance Rp2 and the negative detection resistance Rn2, the third detection resistance group includes the positive detection resistance Rp3 and the negative detection resistance Rn3, and the fourth detection resistance group includes the positive detection resistance Rp4 and the negative detection resistance Rn4. In some embodiments, the diagnostic device controls Rpl and Rnl to be closed in turn, and then obtains two measured resistance values. Then, the diagnostic device controls Rp2 and Rn2 to be closed in turn, and then obtains two measured resistance values. Then, the diagnostic device controls Rp3 and Rn3 to be closed in turn, and then obtains two measured resistance values. Then, the diagnostic device controls Rp4 and Rn4 to be closed in turn, and then obtains two measured resistance values. Through the above-mentioned control of the switches to be closed in turn, 2N measured deviations corresponding to the N detection resistance groups are obtained.

[0103] It can be understood that, in some embodiments, the diagnostic device controls the first switch corresponding to the N positive detection resistances and the second switch corresponding to the N negative detection resistances to be closed in turn, and then obtains 2N measured resistance values. In this embodiment, the closing order of the switches corresponding to the 2N detection resistances is not limited, and it is only required that the switches corresponding to the 2N detection resistances are closed respectively. For example, after the first switches corresponding to the N positive detection resistances are closed in turn, the second switches corresponding to the N negative detection resistances are closed in turn.

[0104] Then, the diagnostic device uploads the measured deviations (2N measured deviations) corresponding to the N detection resistance groups to the server, and the server determines whether the insulation detection function of the electric vehicle is normal or invalid according to the measured deviations corresponding to the N detection resistance groups. For example, if there is a measured deviation greater than or equal to a deviation threshold value in the measured deviations corresponding to the N detection resistance groups, it is determined that the insulation detection function of the electric vehicle is invalid; if the measured deviations corresponding to the N detection resistance groups are all within a certain range, it is determined that the insulation detection function of the electric vehicle is normal.

[0105] In this embodiment, the diagnostic device controls the switches corresponding to the detection resistances in the N detection resistance groups to be closed respectively, that is, 2N detection resistances are turned on respectively and individually, 2N measured deviations are obtained, and the server performs diagnosis based on the 2N measured deviations. For example, if there is a measured deviation greater than or equal to a deviation threshold value in the measured deviations corresponding to the N detection resistance groups, it is determined that the insulation detection function of the electric vehicle is invalid; if the measured deviations corresponding to the N detection resistance groups are all within a certain range, it is determined that the insulation detection function of the electric vehicle is normal.

[0106] Based on the N detection resistor groups corresponding to N resistance value intervals, the diagnosis system can detect the measurement accuracy of the electric vehicle for the resistors in each resistance value interval during each diagnosis, so that the diagnosis result of the insulation detection function is more accurate.

[0107] In some embodiments, if the server continuously detects that the target measurement deviation is greater than or equal to the deviation threshold in the measurement deviations corresponding to the N detection resistor groups for a first preset number of times, it is determined that the insulation detection function of the electric vehicle is invalid. The target measurement deviation is any one of the measurement deviations corresponding to the N detection resistor groups.

[0108] The first preset number of times can be set by those skilled in the art according to actual conditions, for example, the first preset number of times is 3 times. In this embodiment, the diagnosis system diagnoses the electric vehicle multiple times, and obtains the measurement resistances of the 2N detection resistors fed back by the electric vehicle each time to obtain 2N measurement deviations. If the target measurement deviation greater than or equal to the deviation threshold appears in the 2N measurement deviations for 3 consecutive times, it means that the measurement value of the electric vehicle for the detection resistor is inaccurate, and the electric vehicle cannot accurately collect the resistance value of the ground resistance, thereby affecting the insulation detection function and causing the insulation detection function to be invalid.

[0109] In this embodiment, the server can be in communication connection with multiple diagnosis devices, and the multiple diagnosis devices respectively send the measurement data to the server to determine the diagnosis result by the server. Therefore, the electric vehicle can be diagnosed multiple times on different diagnosis devices, and is not restricted by the location of the diagnosis device. If the server continuously detects that the electric vehicle measures the external resistor inaccurately for a first preset number of times, it is determined that the insulation detection function of the electric vehicle is invalid. By continuously restricting for a first preset number of times, the probability of misdiagnosis can be reduced, and the reliability of diagnosis can be improved.

[0110] In some embodiments, the diagnosis device controls the first switch and the second switch corresponding to one of the N detection resistor groups to be closed in turn, and then controls the first switch and the second switch corresponding to the next one of the N detection resistor groups to be closed in turn.

[0111] The diagnosis device uploads the at least one measurement deviation corresponding to the detection resistor group to the server after obtaining the at least one measurement deviation corresponding to the detection resistor group each time, so that the server determines whether the insulation detection function of the electric vehicle is normal or invalid according to the at least one measurement deviation corresponding to the detection resistor group.

[0112] For example, for any one detection resistor group, the detection resistor group includes a positive detection resistor Rpi and a negative detection resistor Rni, the diagnostic device controls the first switch corresponding to the positive detection resistor Rpi to be closed and the second switch corresponding to the negative detection resistor Rni to be closed in sequence, respectively obtains two measurement resistances, and then respectively obtains two measurement deviations based on the actual resistance values of Rpi and Rni. When the diagnostic device obtains at least one of the measurement deviation corresponding to the positive detection resistor Rpi or the measurement deviation corresponding to the negative detection resistor Rni, the diagnostic device uploads the at least one measurement deviation to the server. For example, the diagnostic device uploads the measurement deviation to the server after obtaining the measurement deviation corresponding to the positive detection resistor Rpi or the measurement deviation corresponding to the negative detection resistor Rni, or the diagnostic device uploads the two measurement deviations to the server after obtaining the measurement deviation corresponding to the positive detection resistor Rpi and the measurement deviation corresponding to the negative detection resistor Rni. Thus, when the diagnostic device collects the measurement resistance of the electric vehicle for the detection resistor, the server can determine in real time whether the measurement of the electric vehicle for the detection resistor is abnormal, so as to determine whether the insulation detection function is normal or fails. For example, if the measurement deviation is greater than the deviation threshold, the measurement is abnormal, and the insulation detection function fails; if the measurement deviation is less than or equal to the deviation threshold, the measurement is accurate, and the insulation detection function is normal.

[0113] In this embodiment, after collecting the measurement resistance of the detection resistor in each detection resistor group, real-time uploading is performed, so that the server can determine in real time whether the measurement of the detection resistor is abnormal, thereby determining in real time whether the insulation detection function is normal or fails.

[0114] Based on the fact that the insulation resistance of the positive electrode to ground and the insulation resistance of the negative electrode to ground are both infinite in theory to achieve insulation protection effect, the positive detection resistor and the negative detection resistor are both smaller than the insulation resistance of the positive electrode to ground and the insulation resistance of the negative electrode to ground. Thus, after the first switch or the second switch corresponding to the detection resistor group with the smallest resistance interval is closed, a smaller resistance (less than 100Ω / V) is connected between the battery and the vehicle ground, so that the electric vehicle is not insulated to ground and leakage occurs. Under normal circumstances, the insulation detection module 23 of the battery management system will detect the resistance value of the battery to ground, find that the resistance value is small and the insulation is poor, and there is a risk of electric shock due to leakage, so the battery management system will report an alarm information and cut off the power output end of the battery in time.

[0115] In some embodiments, after the diagnostic device controls the first switch and the second switch corresponding to the detection resistor group with the smallest resistance interval to be closed in sequence, the diagnostic device reads the feedback information of the electric vehicle; and the diagnostic device determines whether the insulation detection function of the electric vehicle is normal or fails according to the feedback information.

[0116] Taking the detection resistor group with the minimum resistance interval as an example, the diagnostic device controls the first switch corresponding to Rpl to be closed, so that the positive terminal of the battery of the electric vehicle is short-circuited. In the case where the insulation detection function is normal, the feedback information sent by the electric vehicle includes the insulation warning information, i.e., reminding the user that a short-circuit and leakage accident has occurred; in the case where the insulation detection function is invalid, the feedback information sent by the electric vehicle does not include the insulation warning information, and the user cannot be reminded. Then, the diagnostic device controls the second switch corresponding to Rn1 to be closed, so that the negative terminal of the battery of the electric vehicle is short-circuited. In the case where the insulation detection function is normal, the feedback information sent by the electric vehicle includes the insulation warning information, reminding the user that a short-circuit and leakage accident has occurred; in the case where the insulation detection function is invalid, the feedback information sent by the electric vehicle does not include the insulation warning information, and the user cannot be reminded.

[0117] It can be understood that the diagnostic device can read the feedback information of the electric vehicle whenever the diagnostic device controls a switch to be closed. After the diagnostic device controls the first switch and the second switch corresponding to the detection resistor group with the minimum resistance interval to be closed in turn, two feedback information can be read. If both of the two feedback information include the warning information, it indicates that the insulation detection function of the electric vehicle is normal; if at least one of the two feedback information does not include the warning information, it indicates that the insulation detection function of the electric vehicle is invalid.

[0118] In this scheme, the diagnostic device can accurately monitor whether the insulation detection function of the electric vehicle is normally warned, and timely detect the event that the insulation detection function is invalid due to communication failure.

[0119] In some embodiments, the diagnostic device uploads at least one feedback information to a server, and the server determines whether the insulation monitoring function of the electric vehicle is normal or invalid according to the at least one feedback information.

[0120] It can be understood that the diagnostic device can read the feedback information of the electric vehicle whenever the diagnostic device controls a switch to be closed. After the diagnostic device controls the first switch and the second switch corresponding to the detection resistor group with the minimum resistance interval to be closed in turn, two feedback information can be read. In this embodiment, the diagnostic device uploads at least one feedback information to a server, for example, uploads the feedback information corresponding to the positive terminal, the feedback information corresponding to the negative terminal, or both of the feedback information. Thus, the server can determine whether the insulation detection function of the electric vehicle is normal or invalid according to the at least one feedback information. For example, when the server receives two feedback information, if both of the two feedback information include the warning information, it indicates that the insulation detection function of the electric vehicle is normal; if at least one of the two feedback information does not include the warning information, it indicates that the insulation detection function of the electric vehicle is invalid.

[0121] In this embodiment, the diagnostic device uploads at least one feedback information to the server, and the server determines whether the insulation monitoring function of the electric vehicle is normal or invalid, so that the server can save the results of multiple diagnoses and analyze the trend of the diagnosis structure after multiple diagnoses. In addition, based on the server, multiple diagnostic devices can be communicatively connected to the server, and the multiple diagnostic devices respectively send feedback information to the server, and the server determines the diagnosis result, so that the electric vehicle can be diagnosed multiple times on different diagnostic devices, without being restricted by the location of the diagnostic device, and the historical diagnosis result can be traced back, so that the diagnosis is more accurate and reliable.

[0122] By storing the feedback information detected by the electric vehicle on different diagnostic devices through the server, the historical trend of the feedback information can be analyzed to accurately determine whether the insulation detection function of the electric vehicle is invalid, to reduce the probability of misdiagnosis, to discover the function failure problem in time, and to improve the safety. The server can present the diagnosis result to the user through the diagnostic device screen, the printing device, the mobile phone APP, the management background and the like. If it is determined that the insulation detection function of the vehicle is invalid, the user is suggested to go to the repair shop for troubleshooting and repair as soon as possible.

[0123] In some embodiments, if the server detects an alarm abnormality in at least one feedback information for a second preset number of consecutive times, it is determined that the insulation detection function of the electric vehicle is invalid.

[0124] Here, the alarm abnormality refers to a case where the first switch or the second switch corresponding to the detection resistance group with the smallest resistance interval is closed, and the feedback information of the electric vehicle should include alarm information but does not include the alarm information.

[0125] The second preset number can be set by those skilled in the art according to actual conditions, for example, the second preset number is 3 times. In this embodiment, the diagnostic system diagnoses the electric vehicle multiple times, and obtains the feedback information sent by the electric vehicle each time. If the feedback information of three times exists alarm abnormality for three consecutive diagnoses, it indicates that the electric vehicle does not accurately report the alarm in the case of short circuit and leakage, and the insulation detection function is invalid.

[0126] In this embodiment, if the server detects that the electric vehicle reports a fault for a second preset number of consecutive times, it is determined that the insulation detection function of the electric vehicle is invalid. By restricting the second preset number of consecutive times, the probability of misdiagnosis can be reduced, and the reliability of the diagnosis can be improved.

[0127] In some embodiments, please continue to refer to Figure 2The diagnostic device further comprises a voltmeter connected between the positive terminal and the negative terminal of the DC bus. When the failure diagnosis is performed, the positive terminal of the DC bus is connected to the positive pole of the battery of the electric vehicle, and the negative terminal of the DC bus is connected to the negative pole of the battery of the electric vehicle, so that the voltmeter can measure the voltage of the battery.

[0128] After the voltage of the battery is measured by the voltmeter, the diagnostic device reads the voltage of the battery of the electric vehicle measured by the voltmeter. If the voltage is the normal output voltage of the battery, the prompt control closes the switch to perform the diagnostic work. It can be understood that if the voltage is the normal output voltage of the battery, it means that the battery of the electric vehicle is connected to the diagnostic device normally, so that the diagnostic work can be started, and therefore the prompt control closes the switch to perform the diagnostic work.

[0129] In this embodiment, the voltage of the battery of the electric vehicle is measured by the voltmeter, and the prompt control closes the switch to perform the diagnostic work under the condition that the battery of the electric vehicle is connected to the diagnostic device normally, so that the diagnostic device is more accurate and safe.

[0130] In some embodiments, after the diagnostic device controls the first switch and the second switch corresponding to the detection resistance group with the smallest resistance interval to be closed in turn, if the diagnostic device reads that the voltage measured by the voltmeter is 0, it is determined that the diagnosis result of the positive pole of the battery of the electric vehicle is normal.

[0131] It can be understood that after the first switch corresponding to the detection resistance group with the smallest resistance interval is closed, the positive pole resistance of the battery of the electric vehicle is the positive pole detection resistance with the smallest resistance, that is, the positive pole of the battery is not insulated from the ground, and there is a risk of positive pole leakage. At this time, if the insulation detection module of the battery management system works normally, it should trigger the cut-off protection, that is, cut off the power output end of the battery in time, so that the output voltage of the battery is 0. Therefore, under the condition that the first switch corresponding to the detection resistance group with the smallest resistance interval is closed, if the diagnostic device reads that the voltage measured by the voltmeter is 0, it means that the insulation detection module of the battery management system can trigger the protection in time for the positive pole insulation fault, and therefore it is determined that the diagnosis result of the positive pole of the battery of the electric vehicle is normal.

[0132] Similarly, after the second switch corresponding to the detection resistance group with the smallest resistance interval is closed, the negative pole resistance of the battery of the electric vehicle is the negative pole detection resistance with the smallest resistance, that is, the negative pole of the battery is not insulated from the ground, and there is a risk of negative pole leakage. At this time, if the insulation detection module of the battery management system works normally, it should trigger the cut-off protection, that is, cut off the power output end of the battery in time, so that the output voltage of the battery is 0. Therefore, under the condition that the second switch corresponding to the detection resistance group with the smallest resistance interval is closed, if the diagnostic device reads that the voltage measured by the voltmeter is 0, it means that the insulation detection module of the battery management system can trigger the protection in time for the negative pole insulation fault, and therefore it is determined that the diagnosis result of the negative pole of the battery of the electric vehicle is normal.

[0133] In this embodiment, the battery management system can timely trigger the cut-off protection after monitoring the risk of electric leakage of the battery of the electric vehicle by the voltmeter, so as to accurately determine whether the positive or negative diagnosis result of the battery of the electric vehicle is normal.

[0134] In some embodiments, referring again to Figure 2 The failure diagnosis system further includes a vehicle communication interface (VCI) device, which is used to communicatively connect the diagnosis device and the electric vehicle. The VCI device is arranged at the periphery of the steering wheel of the vehicle. One port of the VCI device is used to connect to the OBD interface of the vehicle, and the other port is used to connect to the OBD interface of the diagnosis device.

[0135] In summary, the failure diagnosis system of the insulation detection function of the electric vehicle provided by the embodiments of the present application includes a diagnosis device and a server communicatively connected, wherein the diagnosis device includes a direct current bus, N detection resistor groups, and a device ground. Each detection resistor group corresponds to one of N resistance value ranges, and each detection resistor group includes a positive detection resistor and a negative detection resistor. The positive detection resistor is connected to the positive terminal of the direct current bus and the device ground through a first switch, and the negative detection resistor is connected to the negative terminal of the direct current bus and the device ground through a second switch. When performing failure diagnosis, the positive terminal of the direct current bus is connected to the positive terminal of the battery of the electric vehicle, the negative terminal of the direct current bus is connected to the negative terminal of the battery of the electric vehicle, and the diagnosis device is communicatively connected to the electric vehicle. The diagnosis device controls the closing of the switch connected to any one of the positive detection resistor and the negative detection resistor each time, and the switch is one of the first switch and the second switch. After the diagnosis device controls the closing of the switch each time, the diagnosis device reads the measured resistance value of the detection resistor fed back by the electric vehicle. The diagnosis device determines the measurement deviation of the electric vehicle for the detection resistor according to the measured resistance value of the detection resistor and the actual resistance value of the detection resistor. The diagnosis device uploads the measurement deviation to the server, and the server determines whether the insulation detection function of the electric vehicle is normal or fails according to at least one measurement deviation of the electric vehicle for the detection resistor.

[0136] In this diagnosis system, the diagnosis device can accurately monitor the measurement deviation of the electric vehicle for external resistance, and the server can determine whether the detection of the electric vehicle for external resistance is accurate based on the measurement deviation. If the measurement is accurate, the insulation detection function is normal, and if the measurement is not accurate, the insulation detection function fails. Based on the one-to-one correspondence between the N detection resistor groups and the N resistance value ranges, the diagnosis system can detect the measurement accuracy of the electric vehicle for the resistors in each resistance value range in multiple diagnoses, so that the diagnosis result is more accurate.

[0137] Some embodiments of the present application further provide a diagnosis device, which is described with reference toFigure 3 The diagnostic device comprises a direct current bus, N detection resistance groups, a device ground and a processor, and a communication module.

[0138] The processor can be a central processing unit (CPU), a network processor (NP), a hardware chip, or any combination thereof. In some embodiments, the communication module can comprise a communication interface for wired communication connection with the electric vehicle and a network antenna for wireless communication connection with the server.

[0139] Each detection resistance group corresponds to one of the N resistance value intervals, and each detection resistance group comprises a positive detection resistance and a negative detection resistance. The positive detection resistance is connected between the positive terminal of the direct current bus and the device ground through a first switch, and the negative detection resistance is connected between the negative terminal of the direct current bus and the device ground through a second switch. When performing the failure diagnosis, the positive terminal of the direct current bus is connected to the positive terminal of the battery of the electric vehicle, and the negative terminal of the direct current bus is connected to the negative terminal of the battery of the electric vehicle. The device ground refers to the device shell that can be touched by the user.

[0140] N is an integer greater than or equal to 1. For example, N can be 4, and there are four detection resistance groups with different resistance values, i.e., four positive detection resistances with different resistance values and four negative detection resistances with different resistance values. Figure 3 For simplicity, the positive detection resistance Rpi in any one detection resistance group and the corresponding first switch Kpi are connected between the positive terminal of the direct current bus and the device ground, and the negative detection resistance Rni and the corresponding second switch Kni are connected between the negative terminal of the direct current bus and the device ground. It can be understood that in Figure 3 the other detection resistance groups are not shown.

[0141] It can be understood that when performing the failure diagnosis, the positive terminal of the direct current bus is connected to the positive terminal of the battery of the electric vehicle, and the negative terminal of the direct current bus is connected to the negative terminal of the battery of the electric vehicle. If the first switch Kpi is closed, it is equivalent to connecting a positive detection resistance Rpi between the positive terminal of the battery and the device ground. If the second switch Kni is closed, it is equivalent to connecting a negative detection resistance Rni between the negative terminal of the battery and the device ground. Here, the device ground is the ground terminal.

[0142] It can be understood that theoretically, the insulation resistance of the positive electrode to ground and the insulation resistance of the negative electrode to ground are both infinite to achieve insulation protection effect. The positive electrode detection resistance and the negative electrode detection resistance are both smaller than the insulation resistance of the positive electrode to ground and the insulation resistance of the negative electrode to ground. Therefore, when any one of the switches is closed, it is equivalent to connecting a detection resistance between the battery and the vehicle ground, so that the battery is not insulated to ground. Under normal circumstances, the insulation detection module 23 of the battery management system will detect the resistance value of the battery to ground, find that the resistance value is small and the insulation is poor, and there is a risk of electric shock, so the battery management system will report an alarm information and cut off the power supply output end of the battery in time.

[0143] It can be understood that accurate measurement of the insulation resistance of the battery to ground is the premise of triggering the insulation protection function. Generally, the vehicle insulation detection function will trigger a serious fault when the system insulation resistance quantitative value is measured to be lower than 100Ω / V, and will trigger a slight alarm when the system insulation resistance quantitative value is between 100Ω / V and 500Ω / V. Here, the system insulation resistance quantitative value refers to the smaller value of the positive electrode to ground and the negative electrode to ground. It can be understood that the system insulation resistance quantitative value is different for vehicles with different working voltages.

[0144] In order to diagnose the detection accuracy of the battery management system (BMS) to the resistance of each resistance interval, N detection resistance groups with different resistance intervals are set (for example, N is 4), covering 4 resistance intervals. For example, in the 4 resistance intervals of 0Ω / V-100Ω / V, 100Ω / V-500Ω / V, 500Ω / V-2000Ω / V and greater than 2000Ω / V, one resistance value is selected as the resistance value of the positive electrode detection resistance and the negative electrode detection resistance.

[0145] The resistance values of the positive electrode detection resistance and the negative electrode detection resistance can be set according to Table 1. The resistance values of the 4 positive electrode detection resistances and the 4 negative electrode detection resistances are distributed in the 4 resistance intervals of 0Ω / V-100Ω / V, 100Ω / V-500Ω / V, 500Ω / V-2000Ω / V and greater than 2000Ω / V. For each resistance interval, the system insulation resistance quantitative value is different for vehicles with different working voltages. The positive electrode detection resistance or the negative electrode detection resistance in the same resistance interval is smaller than the system insulation resistance quantitative value of different vehicles.

[0146] Based on Figure 3In the structure of the diagnostic device, the processor controls the closure of a switch connected to either the positive or negative detection resistor. This switch is one of the first and second switches. When the switch is closed, it is equivalent to connecting a detection resistor between the battery and the vehicle ground. The electric vehicle's battery management system measures the resistance value of this detection resistor. Since the diagnostic device and the electric vehicle are connected via a communication module, the communication module can read the measured resistance value of the detection resistor fed back by the electric vehicle after each switch closure. For example, for the positive detection resistor Rpi, after controlling the closure of its corresponding first switch Kpi, the insulation detection module 23 of the battery management system measures the resistance value of the battery's positive terminal to ground, i.e., measures the resistance value of the positive detection resistor Rpi. This measured resistance value is called the measured resistance value Rpi_read. Therefore, the communication module reads the measured resistance value Rpi_read fed back by the electric vehicle for the detection resistor Rpi.

[0147] The processor determines the measurement deviation of the electric vehicle for the sensing resistor based on the measured resistance value and the actual resistance value of the sensing resistor. In some embodiments, the measurement deviation of the positive electrode sensing resistor can be calculated using the following formula:

[0148]

[0149] Among them, R pi R is the detection resistor for the i-th positive electrode. pi_read This represents the measured resistance value corresponding to the i-th positive electrode detection resistor.

[0150] Similarly, the measurement deviation of the negative electrode sensing resistor is calculated using the following formula:

[0151]

[0152] Among them, R ni R is the detection resistor for the i-th negative electrode. ni_read This represents the measured resistance value corresponding to the i-th negative electrode detection resistor.

[0153] The processor determines whether the electric vehicle's insulation detection function is normal or malfunctioning based on the measurement deviation of the electric vehicle's resistance to the detection resistor. If the measurement deviation is small, it indicates that the electric vehicle's resistance to ground is measured accurately, and the insulation detection function is normal. If the measurement deviation is large, it indicates that the electric vehicle's resistance to ground is measured inaccurately, and the insulation detection function is malfunctioning.

[0154] It is understood that, in some embodiments, during several consecutive diagnostics, the processor can control the switch connected to the same detection resistor to close, thereby obtaining at least one measurement deviation of the electric vehicle for the detection resistor. Based on at least one measurement deviation, the processor can accurately determine whether the insulation detection function of the electric vehicle is normal or malfunctioning, avoiding diagnostic errors.

[0155] In some embodiments, the processor controls the different detection resistance connected switches to be closed in succession in several times of diagnosis, so that the processor obtains the measurement deviation of the electric vehicle for the plurality of detection resistances. Based on the N detection resistance groups corresponding to the N resistance value intervals, the diagnosis device can detect the measurement accuracy of the electric vehicle for the resistance of each resistance value interval in multiple times of diagnosis, so that the diagnosis result of the insulation detection function is more accurate.

[0156] In some embodiments, after the processor controls the first switch and the second switch corresponding to one detection resistance group in the N detection resistance groups to be closed in turn, the diagnosis device controls the first switch and the second switch corresponding to the next detection resistance group in the N detection resistance groups to be closed in turn. Taking N as 4 as an exemplary illustration, the first detection resistance group includes the positive detection resistance Rp1 and the negative detection resistance Rn1, the second detection resistance group includes the positive detection resistance Rp2 and the negative detection resistance Rn2, the third detection resistance group includes the positive detection resistance Rp3 and the negative detection resistance Rn3, and the fourth detection resistance group includes the positive detection resistance Rp4 and the negative detection resistance Rn4. In some embodiments, after the diagnosis device controls Rp1 and Rn1 to be closed in turn, two measurement resistances are obtained. Then, after the diagnosis device controls Rp2 and Rn2 to be closed in turn, two measurement resistances are obtained. Then, after the diagnosis device controls Rp3 and Rn3 to be closed in turn, two measurement resistances are obtained. Then, after the diagnosis device controls Rp4 and Rn4 to be closed in turn, two measurement resistances are obtained. Through the above-mentioned control of the switches to be closed in turn, 2N measurement deviations corresponding to the N detection resistance groups are obtained.

[0157] It can be understood that, in some embodiments, the processor controls the first switch corresponding to the N positive detection resistances and the second switch corresponding to the N negative detection resistances to be closed in turn to obtain 2N measurement resistances. In this embodiment, the closing order of the switches corresponding to the 2N detection resistances is not limited, and it is only required that the switches corresponding to the 2N detection resistances are closed respectively. For example, after the first switches corresponding to the N positive detection resistances are closed in turn, the second switches corresponding to the N negative detection resistances are closed in turn.

[0158] Then, the processor determines whether the insulation detection function of the electric vehicle is normal or invalid according to the measurement deviations corresponding to the N detection resistance groups. For example, if there is a measurement deviation greater than or equal to a deviation threshold value in the measurement deviations corresponding to the N detection resistance groups, it is determined that the insulation detection function of the electric vehicle is invalid; if the measurement deviations corresponding to the N detection resistance groups are all within a certain range, it is determined that the insulation detection function of the electric vehicle is normal.

[0159] In this embodiment, the processor controls the switches corresponding to the detection resistors in the N detection resistor groups to be closed, that is, 2N detection resistors are turned on respectively, 2N measurement deviations are obtained, and diagnosis is performed based on the 2N measurement deviations. For example, if there is a measurement deviation greater than or equal to the deviation threshold in the measurement deviations corresponding to the N detection resistor groups, it is determined that the insulation detection function of the electric vehicle fails; if the measurement deviations corresponding to the N detection resistor groups are all within a certain range, it is determined that the insulation detection function of the electric vehicle is normal.

[0160] Based on the N detection resistor groups corresponding to the N resistance value intervals, the diagnosis equipment can detect the measurement accuracy of the resistance of each resistance value interval of the electric vehicle during each diagnosis, so that the diagnosis result of the insulation detection function is more accurate.

[0161] In some embodiments, if the processor detects that there is a target measurement deviation greater than or equal to the deviation threshold in the measurement deviations corresponding to the N detection resistor groups for a first preset number of times in succession, it is determined that the insulation detection function of the electric vehicle fails. The target measurement deviation is any one of the measurement deviations corresponding to the N detection resistor groups.

[0162] The first preset number of times can be set by those skilled in the art according to actual conditions, for example, the first preset number of times is 3 times. In this embodiment, the diagnosis equipment diagnoses the electric vehicle multiple times, and obtains the measurement resistance values of the 2N detection resistors fed back by the electric vehicle each time to obtain 2N measurement deviations. If a target measurement deviation greater than or equal to the deviation threshold is detected in the 2N measurement deviations for 3 times in succession, it indicates that the measurement value of the electric vehicle for the detection resistor is inaccurate, and the electric vehicle cannot accurately collect the resistance value of the ground resistance, thereby affecting the insulation detection function and causing the insulation detection function to fail.

[0163] In this embodiment, if the processor detects that the electric vehicle measures the external resistance inaccurately for a first preset number of times in succession, it is determined that the insulation detection function of the electric vehicle has failed. By the constraint of the first preset number of times in succession, the probability of misdiagnosis can be reduced, and the reliability of diagnosis can be improved.

[0164] In some embodiments, after the processor controls the first switch and the second switch corresponding to one of the N detection resistor groups to be closed in turn, the processor controls the first switch and the second switch corresponding to the next one of the N detection resistor groups to be closed in turn.

[0165] The processor obtains at least one measurement deviation corresponding to each detection resistor group each time, and determines whether the insulation detection function of the electric vehicle is normal or fails according to the at least one measurement deviation corresponding to the detection resistor group.

[0166] For example, for any one detection resistor group, the detection resistor group includes a positive detection resistor Rpi and a negative detection resistor Rni, the processor controls the first switch corresponding to the positive detection resistor Rpi to be closed and the second switch corresponding to the negative detection resistor Rni to be closed in sequence, two measurement resistances are obtained respectively, and then two measurement deviations are obtained based on the actual resistance values of Rpi and Rni. The processor determines the corresponding measurement deviation when at least one of the measurement deviation corresponding to the positive detection resistor Rpi or the measurement deviation corresponding to the negative detection resistor Rni is obtained. For example, the processor determines whether the measurement of the electric vehicle for the detection resistor is abnormal in real time when the measurement deviation corresponding to the positive detection resistor Rpi or the measurement deviation corresponding to the negative detection resistor Rni is obtained, or the processor determines whether the measurement of the electric vehicle for the detection resistor is abnormal in real time after the measurement deviation corresponding to the positive detection resistor Rpi and the measurement deviation corresponding to the negative detection resistor Rni are obtained. Thus, it is determined whether the insulation detection function is normal or fails. For example, if the measurement deviation is greater than the deviation threshold, the measurement is abnormal, and the insulation detection function fails. If the measurement deviation is less than or equal to the deviation threshold, the measurement is accurate, and the insulation detection function is normal.

[0167] In this embodiment, after collecting the measurement resistance of the detection resistor in each detection resistor group, real-time detection is performed, so that the diagnosis equipment can confirm whether the measurement of the detection resistor is abnormal in real time, thereby determining whether the insulation detection function is normal or fails in real time.

[0168] Based on the fact that the insulation resistance of the positive electrode of the battery to the ground and the insulation resistance of the negative electrode to the ground are both infinite to achieve insulation protection effect, the positive detection resistor and the negative detection resistor are both smaller than the insulation resistance of the positive electrode of the battery to the ground and the insulation resistance of the negative electrode to the ground. Thus, when the first switch or the second switch corresponding to the detection resistor group with the smallest resistance interval is closed, a smaller resistance (less than 100Ω / V) is connected between the battery and the vehicle ground, so that the electric vehicle is not insulated to the ground and leakage occurs. Under normal circumstances, the insulation detection module 23 of the battery management system will detect the resistance value of the battery to the ground, find that the resistance value is small and the insulation is poor, and there is a risk of electric shock due to leakage, so the battery management system will report an alarm information and cut off the power supply output end of the battery in time.

[0169] In some embodiments, after the processor controls the first switch and the second switch corresponding to the detection resistor group with the smallest resistance interval to be closed in sequence, the feedback information of the electric vehicle is read; and the diagnosis equipment determines whether the insulation detection function of the electric vehicle is normal or fails according to the feedback information.

[0170] Taking the detection resistor group with the minimum resistance interval, Rp1 and Rn1, as an example, the diagnostic device controls the first switch corresponding to Rp1 to be closed, so that the positive terminal of the battery of the electric vehicle is short-circuited. In the case where the insulation detection function is normal, the feedback information sent by the electric vehicle includes the insulation warning information, i.e., the user is reminded that a short-circuit and leakage accident has occurred; in the case where the insulation detection function is invalid, the feedback information sent by the electric vehicle does not include the insulation warning information, and the user cannot be reminded. Then, the diagnostic device controls the second switch corresponding to Rn1 to be closed, so that the negative terminal of the battery of the electric vehicle is short-circuited. In the case where the insulation detection function is normal, the feedback information sent by the electric vehicle includes the insulation warning information, and the user is reminded that a short-circuit and leakage accident has occurred; in the case where the insulation detection function is invalid, the feedback information sent by the electric vehicle does not include the insulation warning information, and the user cannot be reminded.

[0171] It can be understood that the communication module can read the feedback information of the electric vehicle whenever the processor controls a switch to be closed. After the processor controls the first switch and the second switch corresponding to the detection resistor group with the minimum resistance interval to be closed in turn, the communication module can read two feedback information, and if both the two feedback information include the warning information, it indicates that the insulation detection function of the electric vehicle is normal; if at least one of the two feedback information does not include the warning information, it indicates that the insulation detection function of the electric vehicle is invalid.

[0172] In this scheme, the diagnostic device can accurately monitor whether the insulation detection function of the electric vehicle is normally warned, and timely detect the event that the insulation detection function is invalid due to communication failure.

[0173] In some embodiments, if the processor detects that there is a warning abnormality in at least one feedback information for a second preset number of times in succession, it is determined that the insulation detection function of the electric vehicle is invalid.

[0174] Here, the warning abnormality refers to the case where, when the first switch or the second switch corresponding to the detection resistor group with the minimum resistance interval is closed, the feedback information of the electric vehicle should include the warning information but does not include the warning information.

[0175] The second preset number of times can be set by those skilled in the art according to actual conditions, for example, the second preset number of times is 3 times. In this embodiment, the diagnostic device diagnoses the electric vehicle multiple times, and obtains the feedback information sent by the electric vehicle each time. If there is a warning abnormality in the feedback information for 3 times in succession, it indicates that the electric vehicle does not accurately report the warning in the case of short-circuit and leakage, and the insulation detection function is invalid.

[0176] In this embodiment, if the processor detects that the electric vehicle reports a fault for a second preset number of times in succession, it is determined that the insulation detection function of the electric vehicle has failed. By the constraint of the second preset number of times in succession, the probability of misdiagnosis can be reduced, and the reliability of diagnosis can be improved.

[0177] In some embodiments, please refer to Figure 3 , the diagnostic device further comprises a voltmeter connected between the positive terminal and the negative terminal of the DC bus. When performing the failure diagnosis, the positive terminal of the DC bus is connected to the positive electrode of the battery of the electric vehicle, and the negative terminal of the DC bus is connected to the negative electrode of the battery of the electric vehicle, so that the voltmeter can measure the voltage of the battery.

[0178] After the voltmeter measures the voltage of the battery, the processor reads the voltage of the battery of the electric vehicle measured by the voltmeter. If the voltage is the normal output voltage of the battery, the control is prompted to close the switch to perform the diagnostic work. It can be understood that if the voltage is the normal output voltage of the battery, it means that the battery of the electric vehicle is connected normally with the diagnostic device, so that the diagnostic work can be started, and therefore the control is prompted to close the switch to perform the diagnostic work.

[0179] In this embodiment, the voltage of the battery of the electric vehicle is measured by the voltmeter, and the control is prompted to close the switch to perform the diagnostic work under the condition that the battery of the electric vehicle is connected normally with the diagnostic device, so that the diagnostic device is more accurate and safe.

[0180] In some embodiments, after the processor controls the first switch and the second switch corresponding to the detection resistance group with the smallest resistance interval to be closed in turn, if the processor reads that the voltage measured by the voltmeter is 0, it is determined that the diagnostic result of the positive electrode of the battery of the electric vehicle is normal.

[0181] It can be understood that after the first switch corresponding to the detection resistance group with the smallest resistance interval is closed, the positive electrode of the battery of the electric vehicle has the positive electrode detection resistance with the smallest resistance to ground, i.e. the positive electrode of the battery is not insulated to ground, and there is a risk of positive electrode leakage. At this time, if the insulation detection module of the battery management system works normally, it should trigger the cut-off protection, i.e. cut off the power output end of the battery in time, so that the output voltage of the battery is 0. Therefore, under the condition that the first switch corresponding to the detection resistance group with the smallest resistance interval is closed, if the processor reads that the voltage measured by the voltmeter is 0, it means that the insulation detection module of the battery management system can trigger the protection in time for the positive electrode insulation fault, and therefore it is determined that the diagnostic result of the positive electrode of the battery of the electric vehicle is normal.

[0182] Similarly, after the second switch corresponding to the detection resistance group with the minimum resistance interval is closed, the negative electrode of the battery of the electric vehicle is connected to the ground through the negative electrode detection resistance with the minimum resistance, that is, the negative electrode of the battery is not insulated from the ground, and a negative electrode leakage risk occurs. At this time, if the insulation detection module of the battery management system is working normally, the protection of cutting off should be triggered, that is, the power output end of the battery is cut off in time, so that the output voltage of the battery is 0. Therefore, in the case that the second switch corresponding to the detection resistance group with the minimum resistance interval is closed, if the processor reads that the voltage measured by the voltmeter is 0, it indicates that the insulation detection module of the battery management system can trigger the protection in time in the case of a positive electrode insulation fault, and therefore, it is determined that the diagnosis result of the negative electrode of the battery of the electric vehicle is normal.

[0183] In this embodiment, the diagnosis device can monitor whether the battery management system can trigger the protection in time after the battery of the electric vehicle occurs a leakage risk, and can accurately determine whether the diagnosis result of the positive electrode or the negative electrode of the battery of the electric vehicle is normal.

[0184] In summary, the diagnosis device can accurately monitor the measurement deviation of the external resistance of the electric vehicle, and the server can determine whether the detection of the external resistance of the electric vehicle is accurate based on the measurement deviation. If the measurement is accurate, the insulation detection function is normal, and if the measurement is not accurate, the insulation detection function is invalid. Based on the fact that the N detection resistance groups correspond to N resistance intervals one by one, in multiple diagnoses, the diagnosis device can detect the measurement accuracy of the resistance of each resistance interval of the electric vehicle, so that the diagnosis result is more accurate.

[0185] Some embodiments of the present application also provide a diagnosis device, which comprises a direct current bus, N detection resistance groups, a device ground, a processor and a communication module. The processor can be a central processing unit (CPU), a network processor (NP), a hardware chip or any combination thereof. In some embodiments, the communication module can comprise a communication interface for wired communication connection with the electric vehicle and a network antenna for wireless communication connection with the server.

[0186] The N detection resistance groups correspond to N resistance intervals one by one, each detection resistance group comprises a positive electrode detection resistance and a negative electrode detection resistance, the positive electrode detection resistance is connected to the positive electrode end of the direct current bus and the device ground through a first switch, and the negative electrode detection resistance is connected to the negative electrode end of the direct current bus and the device ground through a second switch. When performing the failure diagnosis, the positive electrode end of the direct current bus is connected to the positive electrode of the battery of the electric vehicle, and the negative electrode end of the direct current bus is connected to the negative electrode of the battery of the electric vehicle. The device ground refers to the device shell that can be touched by the user.

[0187] N is an integer greater than or equal to 1, for example, N can be 4, then there are 4 different resistance value interval detection resistance groups, that is, including 4 different resistance value positive detection resistors and 4 different resistance value negative detection resistors. It can be understood that when performing failure diagnosis, the positive terminal of the DC bus is connected to the positive terminal of the electric vehicle battery, and the negative terminal of the DC bus is connected to the negative terminal of the electric vehicle battery. If the first switch Kpi is closed, it is equivalent to connecting a positive detection resistor Rpi between the positive terminal of the battery and the device ground. If the second switch Kni is closed, it is equivalent to connecting a negative detection resistor Rni between the negative terminal of the battery and the device ground. Here, the device ground is the ground terminal.

[0188] It can be understood that in theory, the insulation resistance of the positive terminal of the battery to ground and the insulation resistance of the negative terminal of the battery to ground are both infinite, in order to achieve insulation protection effect. The positive detection resistor and the negative detection resistor are both smaller than the insulation resistance of the positive terminal of the battery to ground and the insulation resistance of the negative terminal of the battery to ground. Therefore, when any one of the switches is closed, it is equivalent to connecting a detection resistor between the battery and the vehicle ground, so that the battery is not insulated to ground. Under normal circumstances, the insulation detection module 23 of the battery management system will detect the resistance value of the battery to ground, find that the resistance value is small and the insulation is poor, and there is a risk of electric shock, then the battery management system will report an alarm information, and cut off the power supply output end of the battery in time.

[0189] It can be understood that accurate measurement of the insulation resistance of the battery to ground is the premise of triggering the insulation protection function. Generally, the vehicle insulation detection function will trigger a serious fault when the system insulation resistance quantitative value is measured to be lower than 100Ω / V, and will trigger a slight alarm when the system insulation resistance quantitative value is between 100Ω / V and 500Ω / V. Here, the system insulation resistance quantitative value refers to the smaller value of the positive terminal to ground and the negative terminal to ground. It can be understood that for vehicles with different working voltages, the system insulation resistance quantitative value is also different.

[0190] In order to diagnose the detection accuracy of the battery management system (BMS) to the resistance of each resistance value interval, N different resistance value interval detection resistance groups are set (for example, N is 4), covering 4 resistance value intervals. For example, in the 4 resistance value intervals of 0Ω / V-100Ω / V, 100Ω / V-500Ω / V, 500Ω / V-2000Ω / V and greater than 2000Ω / V, one resistance value is selected as the resistance value of the positive detection resistor and the negative detection resistor.

[0191] The resistance values of the positive electrode detection resistors and the negative electrode detection resistors can be set with reference to Table 1. The resistance values of the four positive electrode detection resistors and the four negative electrode detection resistors are distributed in four resistance value intervals, i.e., 0 Ω / V-100 Ω / V, 100 Ω / V-500 Ω / V, 500 Ω / V-2000 Ω / V, and greater than 2000 Ω / V. For each resistance value interval, the system insulation resistance quantitative value is different for vehicles with different working voltages. The positive electrode detection resistors or the negative electrode detection resistors in the same resistance value interval are smaller than the system insulation resistance quantitative value of different vehicles.

[0192] The diagnostic device controls the closing of the switch connected to any one of the positive electrode detection resistors and the negative electrode detection resistors each time, and the switch is one of the first switch and the second switch. When the switch is closed, a detection resistor is connected between the battery and the vehicle ground, and the battery management system of the electric vehicle measures the resistance value of the detection resistor. Based on the communication connection between the diagnostic device and the electric vehicle, the communication module can read the measurement resistance value of the detection resistor fed back by the electric vehicle each time the diagnostic device controls the closing of the switch. For example, for the positive electrode detection resistor Rpi, after the closing of the corresponding first switch Kpi is controlled, the insulation detection module 23 of the battery management system measures the resistance value between the positive electrode of the battery and the ground, i.e., the resistance value of the positive electrode detection resistor Rpi, and the measured resistance value is referred to as the measurement resistance value Rpi_read. Thus, the communication module reads the measurement resistance value Rpi_read of the detection resistor Rpi fed back by the electric vehicle.

[0193] The diagnostic device determines the measurement deviation of the electric vehicle for the detection resistor according to the measurement resistance value of the detection resistor and the actual resistance value of the detection resistor. In some embodiments, the measurement deviation of the positive electrode detection resistor can be calculated by using the following formula:

[0194]

[0195] wherein, Rpi is the i-th positive electrode detection resistor, Rpi_actual is the actual resistance value of the i-th positive electrode detection resistor, and Rpi_read is the measurement resistance value of the i-th positive electrode detection resistor. pi pi_read

[0196] Similarly, the measurement deviation of the negative electrode detection resistor can be calculated by using the following formula:

[0197]

[0198] wherein, Rni is the i-th negative electrode detection resistor, Rni_actual is the actual resistance value of the i-th negative electrode detection resistor, and Rni_read is the measurement resistance value of the i-th negative electrode detection resistor. ni ni_read

[0199] ​​​​The communication module of the diagnosis device uploads the measurement deviation to the server, and the server determines whether the insulation detection function of the electric vehicle is normal or invalid according to the measurement deviation of the electric vehicle for the detection resistor. If the measurement deviation is small, it indicates that the electric vehicle measures the ground resistance accurately, and the insulation detection function is normal. If the measurement deviation is large, it indicates that the electric vehicle measures the ground resistance inaccurately, and the insulation detection function is invalid.

[0200] It can be understood that in some embodiments, the diagnosis device can control the same detection resistor connected switch to be closed during several consecutive diagnoses, so that the server obtains at least one measurement deviation of the electric vehicle for the detection resistor, and based on the at least one measurement deviation, the insulation detection function of the electric vehicle can be accurately determined to be normal or invalid, avoiding diagnosis errors.

[0201] In some embodiments, the diagnosis device can control different detection resistor connected switches to be closed during several consecutive diagnoses, so that the server obtains measurement deviations of the electric vehicle for multiple detection resistors. Based on the N detection resistor group corresponding to the N resistance value interval, the measurement accuracy of the electric vehicle for the resistance of each resistance value interval can be detected in multiple diagnoses, so that the diagnosis result of the insulation detection function is more accurate.

[0202] Some embodiments of the present application also provide a charging pile including the diagnosis device in any one of the above embodiments. The structure and function of the diagnosis device are the same as those of the diagnosis device in some embodiments described above, and will not be repeated here.

[0203] The charging pile can periodically diagnose whether the insulation detection function is valid before or after charging the electric vehicle, so as to timely find the insulation detection function invalid problem, and improve the convenience and timeliness.

[0204] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; under the idea of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above. In order to be brief, they are not provided in details; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A failure diagnosis system for insulation detection function in electric vehicles, characterized in that, The diagnostic device and the server are connected in communication, the diagnostic device comprises a direct current bus, N detection resistance groups and a device ground, each of the N detection resistance groups corresponds to a resistance interval, each of the detection resistance groups comprises a positive detection resistance and a negative detection resistance, the positive detection resistance is connected to a positive terminal of the direct current bus and the device ground through a first switch, and the negative detection resistance is connected to a negative terminal of the direct current bus and the device ground through a second switch, wherein N is an integer greater than or equal to 1; the positive terminal of the direct current bus is used for connecting a positive electrode of a battery of an electric vehicle, the negative terminal of the direct current bus is used for connecting a negative electrode of the battery of the electric vehicle, and the diagnostic device is further used for being connected in communication with the electric vehicle; the diagnostic device controls the first switch and the second switch corresponding to one of the N detection resistance groups to be closed in turn, and then controls the first switch and the second switch corresponding to the next one of the N detection resistance groups to be closed in turn. The diagnostic device reads a measured resistance value of the detection resistance fed back by the electric vehicle after each time the switch is controlled to be closed. The diagnostic device determines a measurement deviation of the electric vehicle for the detection resistance according to the measured resistance value of the detection resistance and an actual resistance value of the detection resistance. The diagnostic device uploads the measurement deviations corresponding to the N detection resistance groups to the server, and the server determines that the insulation detection function of the electric vehicle is normal or invalid according to the measurement deviations corresponding to the N detection resistance groups.

2. The system of claim 1, wherein, If the server detects that a target measurement deviation greater than or equal to a deviation threshold exists in the measurement deviations corresponding to the N detection resistance groups for a first preset number of times in succession, it is determined that the insulation detection function of the electric vehicle is invalid, and the target measurement deviation is any one of the measurement deviations corresponding to the N detection resistance groups.

3. The system of claim 1, wherein, The diagnostic device controls the first switch and the second switch corresponding to one of the N detection resistance groups to be closed in turn, and then controls the first switch and the second switch corresponding to the next one of the N detection resistance groups to be closed in turn. The diagnostic device uploads at least one measurement deviation corresponding to a detection resistance group to the server after obtaining the at least one measurement deviation corresponding to the detection resistance group each time, and the server determines that the insulation detection function of the electric vehicle is normal or invalid according to the at least one measurement deviation corresponding to the detection resistance group.

4. The system of any of claims 1-3, wherein, The diagnostic device reads feedback information of the electric vehicle after controlling the first switch and the second switch corresponding to the detection resistance group with the smallest resistance interval to be closed in turn. The diagnostic device determines that the insulation detection function of the electric vehicle is normal or invalid according to the feedback information.

5. The system of claim 4, wherein, The diagnostic device uploads at least one of the feedback information to the server, and the server determines that the insulation monitoring function of the electric vehicle is normal or invalid according to the at least one of the feedback information.

6. The system of claim 5, wherein, If the server detects the alarm abnormality in at least one of the feedback information for a second preset number of times in succession, it is determined that the insulation detection function of the electric vehicle is invalid.

7. The system of claim 4, wherein, The diagnostic device further comprises a voltmeter connected between the positive terminal and the negative terminal of the DC bus; The diagnostic device reads the voltage measured by the voltmeter before the diagnostic device controls the first switch and the second switch corresponding to the detection resistance group with the smallest resistance interval to be closed in turn, and if the voltage is the normal output voltage of the battery, it prompts the control to close the switch to perform the diagnosis work.

8. The system of claim 7, wherein, The system further comprises a vehicle communication interface device for communicatively connecting the diagnostic device and the electric vehicle.

9. The system of claim 1, wherein, The system comprises a DC bus, N detection resistance groups, a device ground, a processor, and a communication module.

10. A diagnostic device, characterized by Each of the N detection resistance groups corresponds to one of N resistance intervals, and each of the detection resistance groups comprises a positive detection resistance and a negative detection resistance. The positive terminal of the DC bus is used to connect the positive electrode of the battery of the electric vehicle, and the negative terminal of the DC bus is used to connect the negative electrode of the battery of the electric vehicle. The processor controls the first switch and the second switch corresponding to one of the N detection resistance groups to be closed each time, and then controls the first switch and the second switch corresponding to the next one of the N detection resistance groups to be closed in turn. The communication module reads the measured resistance value of the detection resistance group fed back by the electric vehicle after the processor controls the switch to be closed each time. The processor determines the measurement deviation of the electric vehicle for the detection resistance according to the measured resistance value of the detection resistance and the actual resistance value of the detection resistance. The processor determines whether the insulation detection function of the electric vehicle is normal or invalid according to the measurement deviation of the electric vehicle for the N detection resistance groups. The system comprises a DC bus, N detection resistance groups, a device ground, a processor, and a communication module.

11. A diagnostic device, characterized by Each of the N detection resistance groups corresponds to one of N resistance intervals, and each of the detection resistance groups comprises a positive detection resistance and a negative detection resistance. The positive terminal of the DC bus is used to connect the positive electrode of the battery of the electric vehicle, and the negative terminal of the DC bus is used to connect the negative electrode of the battery of the electric vehicle. The positive terminal of the direct current bus is used for connecting the positive pole of the battery of the electric vehicle, the negative terminal of the direct current bus is used for connecting the negative pole of the battery of the electric vehicle, and the communication module is used for being communicatively connected with a server and the electric vehicle respectively; After the processor controls the first switch and the second switch corresponding to one of the N groups of detection resistors to be closed each time, the diagnostic device controls the first switch and the second switch corresponding to the next one of the N groups of detection resistors to be closed in turn; After the processor controls the switch to be closed each time, the communication module reads the measured resistance value of the detection resistor fed back by the electric vehicle; The processor determines the measurement deviation of the electric vehicle for the detection resistor according to the measured resistance value of the detection resistor and the actual resistance value of the detection resistor; The communication module uploads the measurement deviation to the server, so that the server determines whether the insulation detection function of the electric vehicle is normal or invalid according to the measurement deviation corresponding to the N groups of detection resistors of the electric vehicle.

12. A charging station, characterized in that The diagnostic device as claimed in claim 10 or 11.

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