An electric vehicle troubleshooting system and method

Abstract

The application discloses a kind of electric vehicle troubleshooting system and method, system includes parallel in electric vehicle bus on pre-charging detection module and pre-charging detection loop module;Pre-charging detection loop module includes several parallel pre-charging detection branch, each pre-charging detection branch is connected with electric vehicle bus, and each pre-charging detection branch includes high voltage component and is used to control the high voltage relay of current pre-charging detection branch on-off;The detection end of pre-charging detection module is connected with electric vehicle bus, and the power supply end of pre-charging detection module is connected with electric vehicle battery system, and pre-charging detection module is used to according to the resistance value and / or pipe voltage drop value of electric vehicle bus, pre-charging troubleshooting is carried out to the high voltage component corresponding to high voltage relay.The electric vehicle troubleshooting system and method provided in the embodiment of the application realize the insulation and pre-charging troubleshooting of automation.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle fault detection technology, and in particular to an electric vehicle fault diagnosis system and method. Background Technology

[0002] As electric vehicles become more widely used, pre-charging failures in existing electric vehicles are becoming more and more common.

[0003] In the existing technology, the fault diagnosis method for electric vehicles is manual. For example, for insulation faults, the insulation resistance of the electric vehicle bus is measured by using an automatic fault detection function or an external insulation meter. For pre-charge faults, the voltage drop of the electric vehicle bus is measured by using a multimeter diode. If there is an abnormality, the high-voltage component connectors are checked one by one by manually plugging and unplugging them.

[0004] Therefore, how to achieve automated fault detection has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides an electric vehicle fault diagnosis system and method to solve the technical problem of how to achieve automated fault diagnosis of electric vehicles, so as to achieve the effect of automated fault detection.

[0006] To address the aforementioned technical problems, this invention provides an electric vehicle fault diagnosis system, including a pre-charge detection module and a pre-charge detection circuit module connected in parallel to the electric vehicle bus.

[0007] The pre-charge detection circuit module includes several parallel pre-charge detection branches. Each pre-charge detection branch is connected to the electric vehicle bus, and each pre-charge detection branch includes a high-voltage component and a high-voltage relay for controlling the on / off state of the current pre-charge detection branch.

[0008] The detection end of the precharge detection module is connected to the electric vehicle bus, and the power supply end of the precharge detection module is connected to the electric vehicle battery system. The precharge detection module is used to troubleshoot precharge faults of the high-voltage component corresponding to the high-voltage relay based on the resistance value and / or voltage drop value of the electric vehicle bus.

[0009] As one preferred embodiment, the electric vehicle fault diagnosis system further includes a secondary insulation detection module, a main positive relay, and a main negative relay;

[0010] The detection terminal of the secondary insulation detection module is connected to the positive terminal of the electric vehicle bus via the main positive relay. The detection terminal of the secondary insulation detection module is also connected to the negative terminal of the electric vehicle bus via the main negative relay. The power supply terminal of the secondary insulation detection module is connected to the external electric vehicle battery system. The secondary insulation detection module is used to control the selected high-voltage relay to detect insulation faults in the high-voltage components.

[0011] This invention provides a method for troubleshooting electric vehicle faults, applied to any of the above-described electric vehicle fault troubleshooting systems. The method includes:

[0012] When a precharge fault code is detected, the system enters the precharge fault troubleshooting mode.

[0013] Based on the detected power battery voltage and insulation resistance values ​​of the electric vehicle battery system, determine whether an internal pre-charge fault has occurred in the power battery.

[0014] When the fault is not due to an internal pre-charge fault of the power battery, the resistance value and / or voltage drop value of the electric vehicle bus are used to determine whether a high-voltage component pre-charge fault has occurred.

[0015] As one preferred embodiment, after disconnecting all the high-voltage relays, if an insulation fault code is read, an abnormal voltage is detected in the power battery, or an abnormal insulation resistance is detected, it is determined that an internal pre-charge fault has occurred in the power battery.

[0016] As one preferred solution, the pre-charge detection module is activated when no insulation fault code is read, no abnormal voltage is detected in the power battery, or no abnormal insulation resistance is detected.

[0017] After the pre-charge detection module is started, each of the high-voltage relays is closed in sequence, and the feedback result of the pre-charge detection module after each closure is read, until the pre-charge detection module detects that the resistance value and / or the pipe voltage drop value of the electric vehicle bus is abnormal.

[0018] When an abnormality is detected in the resistance value and / or pipe voltage drop value of the electric vehicle bus, it is determined that the corresponding high-voltage component has a pre-charge fault.

[0019] As one preferred embodiment, the electric vehicle fault diagnosis method further includes the following steps before disconnecting all the high-voltage relays:

[0020] Under the condition of high-voltage power-on control of the whole vehicle, the pre-charge fault code is read;

[0021] Under the high-voltage power control conditions of the whole vehicle, after clearing the pre-charge fault code, disconnect all the high-voltage relays.

[0022] As one preferred embodiment, the abnormal resistance values ​​of the electric vehicle bus include any one of the following: the positive / negative resistance values ​​are different from the negative / positive resistance values; the ratio of the positive / negative resistance values ​​to the negative / positive resistance values ​​or the ratio of the negative / positive resistance values ​​to the positive / negative resistance values ​​is greater than a first threshold; or the positive / negative resistance values ​​and the negative / positive resistance values ​​are greater than a second threshold.

[0023] The abnormal conditions of the pipe pressure drop value include any one of the following: the positive / negative pipe pressure drop value is different from the negative / positive pipe pressure drop value; the positive / negative pipe pressure drop value is less than the third threshold and the negative / positive pipe pressure drop value cannot be detected; the positive / negative pipe pressure drop value cannot be detected and the negative / positive pipe pressure drop value is less than the third threshold value.

[0024] As one preferred embodiment, the electric vehicle fault diagnosis method further includes:

[0025] After detecting an insulation resistance value less than a first preset value and reading the insulation fault code, it is determined that the first insulation fault troubleshooting mode has been satisfied. Based on the action feedback information of the read insulation fault code, it is determined whether a power battery insulation fault or a high-voltage component insulation fault has occurred; and,

[0026] After detecting that the insulation resistance value is less than the second preset value and no insulation fault code is read, it is determined that the second insulation fault troubleshooting mode is satisfied. Based on the action feedback information of the read insulation resistance value, it is determined whether a power battery insulation fault or a high-voltage component insulation fault has occurred.

[0027] As one preferred embodiment, the determination that the first insulation fault investigation mode is satisfied, and the determination of whether a power battery insulation fault or a high-voltage component insulation fault has occurred based on the action feedback information of the read insulation fault code, includes:

[0028] When the first insulation fault investigation mode is met, if the insulation fault code is detected to reappear after being cleared, then the type of insulation fault is determined to be the power battery insulation fault; and,

[0029] When the first insulation fault troubleshooting mode is met, if no insulation fault code is detected to reappear after clearing the insulation fault code, an insulation fault code reappearance action is executed, and each of the high-voltage relays is disconnected in sequence until no reappearance of the insulation fault code is detected and / or the insulation resistance value is detected to meet the first preset value. It is then determined that the corresponding high-voltage component has an insulation fault. The insulation fault code reappearance action includes shielding the vehicle controller and controlling the main positive relay and the main negative relay in the electric vehicle fault troubleshooting system to close.

[0030] As one preferred embodiment, the determination that the second insulation fault investigation mode is satisfied, based on the action feedback information of the read insulation resistance value, determines whether a power battery insulation fault or a high-voltage component insulation fault has occurred, including:

[0031] When the second insulation fault investigation mode is met, if the insulation resistance value is detected to reappear after being cleared, then the type of insulation fault is determined to be the power battery insulation fault; and,

[0032] When the second insulation fault investigation mode is met, if the insulation resistance value is not detected to reappear after clearing the insulation resistance value, the insulation resistance value reappearance action is executed, and each of the high-voltage relays is closed in sequence until the detected insulation resistance value meets the second preset value. It is then determined that the high-voltage component currently has an insulation fault. The insulation resistance value reappearance action includes operating the secondary insulation detection module in the electric vehicle fault investigation system.

[0033] Compared with the prior art, the beneficial effects of the embodiments of the present invention are at least one of the following:

[0034] (1) The fault diagnosis system and the fault diagnosis method based on the electric vehicle fault diagnosis system of the present invention do not require manual measurement of each component parameter and manual analysis, which greatly reduces the manpower and time cost of fault diagnosis and realizes automated insulation and pre-charge fault diagnosis.

[0035] (2) When a vehicle malfunctions, the sampling frequency of data detected by manual means is low, and in many cases it is even impossible to collect data on occasional malfunctions, resulting in failure to troubleshoot. This circuit and method can continuously collect parameters of components, with a high sampling frequency and long cycle, which is especially effective for troubleshooting and analyzing occasional malfunctions. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of an electric vehicle fault diagnosis system in one embodiment of the present invention;

[0037] Figure 2 This is a schematic flowchart of a method for troubleshooting pre-charging faults in electric vehicles, according to one embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the structure of an electric vehicle pre-charging and insulation fault diagnosis system in one embodiment of the present invention;

[0039] Figure 4 This is a flowchart of a pre-charging fault diagnosis method based on an electric vehicle pre-charging and insulation fault diagnosis system, according to one embodiment of the present invention.

[0040] Figure 5 This is a flowchart of a method for troubleshooting an electric vehicle insulation resistance value that is less than a preset threshold and an insulation fault is reported, based on an electric vehicle pre-charging and insulation fault troubleshooting system, according to one embodiment of the present invention.

[0041] Figure 6 This is a flowchart of a method for troubleshooting an electric vehicle insulation resistance value that is less than a preset threshold and does not report an insulation fault, based on an electric vehicle pre-charging and insulation fault troubleshooting system, according to one embodiment of the present invention.

[0042] Figure label:

[0043] The components include: 1. Electric vehicle fault diagnosis system; 2. Pre-charge detection circuit module; 21. Pre-charge detection branch; 211. High-voltage relay; 212. High-voltage components; 3. Pre-charge detection module; 4. Insulation and pre-charge detection unit; 5. Battery management system; 6. Secondary insulation detection module; 7. Main positive relay; 8. Main negative relay; 9. Electric vehicle bus. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] In the description of this application, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] In the description of this application, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0048] When electric vehicles are charging, a pre-charging circuit is usually installed to avoid excessive current from adversely affecting the relays. The main function of the pre-charging circuit is to charge the pre-charging capacitor of the motor controller, thereby reducing the sparking and arcing phenomenon generated when the high-voltage relay 211 is closed, thus preventing high-voltage surges from damaging components and improving the safety performance of the entire high-voltage system.

[0049] In the pre-charging mechanism of electric vehicles, if an abnormality occurs during the pre-charging process, such as the charging time being too long and failing to reach the expected voltage, it is considered a pre-charging fault. A pre-charging fault may cause the high-voltage system to malfunction, thereby affecting the charging and driving performance of the new energy vehicle. If the pre-charging fault is not repaired in time, it may also damage other components of the high-voltage system and increase maintenance costs.

[0050] Precharge fault codes are specific codes recorded and generated by the battery system or related battery management system of an electric vehicle or new energy vehicle when a problem occurs during the precharge phase. These codes are used to indicate the specific type of fault that occurs during the precharge process so that maintenance personnel can quickly locate and resolve the problem.

[0051] Meanwhile, insulation failure is also a possible fault in the electrical system of electric vehicles, posing a threat to the safety and reliability of electric vehicles. Insulation failure refers to the phenomenon of short circuit, leakage and other phenomena caused by the damage of insulation materials in electrical equipment or circuits. In electric vehicles, insulation failure may damage high-voltage components such as batteries and motors, and may even cause serious accidents such as fires.

[0052] Insulation fault codes are fault information recorded by the battery system or related battery management system of an electric vehicle when abnormal insulation resistance is detected. Insulation faults can also cause the insulation resistance value of electrical equipment or lines to deviate from the normal range. Under normal circumstances, the insulation resistance should be high enough to prevent current leakage to the surrounding environment or other non-conductive parts.

[0053] There are two types of judgments regarding abnormal insulation resistance values. The first is below the standard value. Different electric vehicle electrical equipment and lines have corresponding insulation resistance qualification standards based on their voltage level, operating environment, and other factors. When the measured insulation resistance value is lower than the specified standard value, it is considered an abnormal insulation resistance value. The second is unstable fluctuation. If a significant fluctuation in the insulation resistance value is found during regular testing of electrical equipment or lines, this is also an abnormal situation.

[0054] When insulation is severely damaged and the insulation resistance is almost zero, the current will bypass the normal conductive path and flow directly between conductors at different potentials, thus causing a short circuit. A short circuit will generate a large current, which may lead to serious consequences such as damage to the electrical equipment of electric vehicles and fire.

[0055] To troubleshoot pre-charge and insulation faults, one embodiment of the present invention provides an electric vehicle fault diagnosis system. For details, please refer to [link to relevant documentation]. Figure 1 , Figure 1 The image shows an electric vehicle fault diagnosis system according to one embodiment of the present invention.

[0056] The electric vehicle fault diagnosis system 1 includes a pre-charge detection module 3 and a pre-charge detection circuit module 2 connected in parallel to the electric vehicle bus.

[0057] The precharge detection circuit module 2 includes several parallel precharge detection branches. Each precharge detection branch is connected to the electric vehicle bus, and each precharge detection branch includes a high-voltage component 212 and a high-voltage relay 211 for controlling the current high-voltage component 212.

[0058] The precharge detection module 3 includes a resistance detection circuit and / or a tube voltage drop detection circuit. The detection terminals of the resistance detection circuit and / or tube voltage drop detection circuit are connected to the electric vehicle bus, and the power supply terminals of the resistance detection circuit and / or tube voltage drop detection circuit are connected to the external electric vehicle battery system. The precharge detection module 3 is used to control the selected high-voltage relay 211 to realize the precharge fault diagnosis of the high-voltage component 212.

[0059] Among them, the resistance detection circuit includes the volt-ampere method detection circuit, the Wheatstone bridge method detection circuit, and the substitution method detection circuit, etc., and the tube voltage drop detection circuit includes the IGBT tube voltage drop detection circuit, the diode tube voltage drop detection circuit, and the self-driven power semiconductor conduction voltage drop detection circuit, etc. The working principles of different detection circuits are also different, which will not be described in detail here.

[0060] Specifically, the precharge detection module 3 is used to monitor the precharge voltage and current in real time, and to troubleshoot precharge faults in the electric vehicle's power battery and the high-voltage component 212 corresponding to the high-voltage relay 211. The precharge detection module 3 is powered by the electric vehicle's low-voltage battery or an external electric vehicle battery system. The resistance detection circuit detects the positive / negative resistance value and the negative / positive resistance value of the bus, and the tube voltage drop detection circuit detects the positive / negative tube voltage drop value and the negative / positive tube voltage drop value of the bus, thereby realizing the troubleshooting of precharge faults.

[0061] Among them, the electric vehicle bus is the core conductive component in the electric vehicle system. It is mainly responsible for transmitting electrical energy and connecting the battery pack, motor controller and various high-voltage components 212. The bus transmits electrical energy by conducting DC current internally to ensure the normal operation of the electric vehicle.

[0062] In a specific embodiment, the electric vehicle fault diagnosis system 1 further includes a secondary insulation detection module, a main positive relay, and a main negative relay. The detection end of the secondary insulation detection module is connected to the positive terminal of the electric vehicle bus via the main positive relay, and the detection end of the secondary insulation detection module is also connected to the negative terminal of the electric vehicle bus via the main negative relay. The power supply end of the secondary insulation detection module is connected to the external electric vehicle battery system. The secondary insulation detection module is used to control the selected high-voltage relay 211 to realize the insulation fault diagnosis of the high-voltage component 212.

[0063] Specifically, the secondary insulation detection module can monitor the insulation resistance value of power equipment in real time and predict the trend of insulation faults through data analysis. Once the insulation resistance value is detected to be too low, the module will issue an alarm message to remind the user or vehicle control system to carry out maintenance.

[0064] During operation, the main positive relay and the main negative relay control the connection and disconnection of the positive and negative circuits of the battery pack, ensuring the safe, stable and efficient operation of the battery pack.

[0065] In this embodiment, the secondary insulation detection module includes a boost chopper circuit, and the voltage output terminal of the boost chopper circuit is connected to the electric vehicle bus.

[0066] In the automotive electrical system, the positive terminal of the bus is usually connected to the positive terminal of the power source or the positive terminal of the battery, and transmits electrical energy to various high-voltage components 212 through the bus. The negative terminal of the bus is usually connected to the negative terminal of the power source or the negative terminal of the battery, and transmits electrical energy to various high-voltage components 212 through the bus.

[0067] In a specific embodiment, the electric vehicle high-voltage electrical architecture also includes a pre-charge detection circuit module 2. The pre-charge detection circuit module 2 includes several parallel pre-charge detection branches. Each pre-charge detection branch is connected to the electric vehicle bus, and each pre-charge detection branch includes a high-voltage component 212 and a high-voltage relay 211 for controlling the current high-voltage component 212. A high-voltage relay 211 is designed at the high-voltage end of each high-voltage component 212. The various pre-charge detection branches are connected in parallel and connected to the pre-charge detection module 3.

[0068] Specifically, the high-voltage components 212 mainly include drive motors, high-voltage distribution boxes, electric compressors, on-board chargers, and motor controllers, etc. This is only an illustrative example, and the specific high-voltage components 212 shall be based on the specific electric vehicle.

[0069] In electric vehicles, each high-voltage component 212 corresponds to a high-voltage relay 211. The high-voltage relay 211 acts as a controlled switch device, precisely controlling the on / off state of each high-voltage component 212. When a high-voltage component 212 needs to operate, the corresponding high-voltage relay 211 closes, allowing current to flow; when the component does not need to operate, the relay opens, cutting off the current. Simultaneously, the high-voltage relay 211 can also serve as a starting point for troubleshooting.

[0070] The electric vehicle fault diagnosis system 1 can perform pre-charge fault diagnosis, diagnosis of electric vehicle insulation resistance value less than preset threshold and reporting insulation fault, and diagnosis of insulation resistance value less than preset threshold and not reporting insulation fault.

[0071] One embodiment of the present invention provides a method for troubleshooting pre-charging faults in electric vehicles. For details, please refer to [link / reference]. Figure 2 , Figure 2 The diagram shown is a flowchart of a pre-charge fault troubleshooting method in one embodiment of the present invention.

[0072] In this embodiment, the precharge fault diagnosis and judgment conditions are as follows:

[0073] When a precharge fault code is detected, the system enters the precharge fault troubleshooting mode.

[0074] Based on the detected power battery voltage and insulation resistance values ​​of the electric vehicle battery system, determine whether an internal pre-charge fault has occurred in the power battery.

[0075] When the fault is not due to an internal pre-charge fault of the power battery, the resistance value and / or voltage drop value of the electric vehicle bus can be used to determine whether a high-voltage component pre-charge fault has occurred.

[0076] Based on the criteria for troubleshooting pre-charge faults, the specific process for troubleshooting pre-charge faults is as follows:

[0077] S1: After disconnecting all high-voltage relays 211, if an insulation fault code is read, an abnormal voltage is detected in the power battery, or an abnormal insulation resistance is detected, it is determined that an internal pre-charge fault of the power battery has occurred.

[0078] S2: When no insulation fault code is read, no abnormal voltage is detected in the power battery, or no abnormal insulation resistance is detected, the pre-charge detection module is activated.

[0079] S3: After starting the pre-charge detection module, close each high-voltage relay 211 in sequence, and read the feedback result of the pre-charge detection module after each closure until the pre-charge detection module detects that the resistance value and / or pipe voltage drop value of the electric vehicle bus is abnormal.

[0080] S4: When an abnormal resistance value and / or pipe voltage drop value is detected in the electric vehicle bus, it is determined that the corresponding high-voltage component 212 has a high-voltage component pre-charge fault.

[0081] Before the control insulation and precharge fault detection unit disconnects all high-voltage relays 211, the following steps must be performed:

[0082] Under the condition of vehicle high voltage power-on control, read the pre-charge fault code; under the condition of vehicle high voltage power-off control, clear the pre-charge fault code and then execute the step of disconnecting all high voltage relays 211.

[0083] The high-voltage power-on control of the vehicle is a key step in starting a new energy vehicle. Based on the driver's control of the ignition key switch, the vehicle controller receives the start signal and controls the high-voltage circuit of the power battery by controlling the high-voltage contactor switch.

[0084] The high-voltage power-off control of the vehicle is a necessary step when a new energy vehicle is shut down to ensure the safe stopping of the vehicle. The vehicle control unit (VCU) sends instructions to each controller to stop working and disconnect the high-voltage circuit according to the driver's shutdown signal or emergency situation.

[0085] Specifically, the pre-charging fault diagnosis method implemented based on the electric vehicle fault diagnosis system 1 includes the following steps:

[0086] Step 1: Under the condition of vehicle high-voltage power-on control, the normal operation is to turn the key to the On position and press the foot brake pedal to read the pre-charge fault code. If it exists, proceed to Step 2 under the condition of vehicle high-voltage power-off control.

[0087] Step 2: Clear the pre-charge fault codes of the entire vehicle. After a period of time, disconnect all high-voltage components and 212 relays. Under the condition of high-voltage power-on control of the entire vehicle, read the voltage, insulation resistance and fault codes of the power battery. If the voltage or insulation resistance of the power battery is abnormal or an insulation fault code appears, it is determined that the power battery has an internal pre-charge fault. If the above abnormalities do not occur, proceed to Step 3.

[0088] Step 3: Activate the pre-charge detection module 3 to determine the bus resistance value and / or pipe voltage drop value;

[0089] Step 4: Sequentially close high-voltage relay 211 and read the feedback result of pre-charge detection module 3 after each closure of high-voltage relay 211 until pre-charge detection module 3 detects abnormal resistance value and / or pipe voltage drop value of the bus. Based on the resistance value and / or pipe voltage drop value of the electric vehicle bus, output the electric vehicle fault type as pre-charge fault of high-voltage component of electric vehicle connected to high-voltage relay 211 when the resistance value and / or pipe voltage drop value of the bus is abnormal.

[0090] In this embodiment, the resistance value refers to the resistance generated by the electric vehicle bus when transmitting current, and the pipe voltage drop value refers to the voltage drop generated due to the presence of resistance when current passes through a pipe or wire.

[0091] Abnormal resistance values ​​of electric vehicle busbars include differences between positive / negative resistance values ​​and negative / positive resistance values, a ratio of positive / negative resistance values ​​to negative / positive resistance values ​​or a ratio of negative / positive resistance values ​​to positive / negative resistance values ​​greater than a first threshold, and positive / negative resistance values ​​and negative / positive resistance values ​​greater than a second threshold.

[0092] Under normal circumstances, the resistance value of the busbar in an electric vehicle should be stable and should not change due to changes in the direction of current. If the positive / negative resistance values ​​are different from the negative / positive resistance values, this may indicate that the busbar has asymmetrical resistance characteristics, which may be caused by factors such as uneven busbar material, poor connection, or interference from the external environment.

[0093] When the ratio of positive / negative resistance value to negative / positive resistance value or the ratio of negative / positive resistance value to positive / negative resistance value is greater than the first threshold (usually greater than 1000), this abnormal ratio indicates that the change in bus resistance value exceeds the normal range. The first threshold is a preset critical value used to determine whether the change in resistance value is significant. If the ratio is greater than the first threshold, it means that there is a fault in the electric vehicle bus or high-voltage component 212, resulting in a resistance problem, such as a sharp increase in resistance or unstable resistance.

[0094] When the positive / negative resistance value and the negative / positive resistance value are greater than the second threshold, the second threshold is greater than 2 megohms. The second threshold is a preset upper limit of resistance value used to determine whether the bus resistance is within an acceptable range. If the resistance value is greater than the second threshold, it means that the electric vehicle bus resistance is too large, thereby increasing the loss in the current transmission process.

[0095] Abnormal pipe pressure drop values ​​include: the positive / negative pipe pressure drop values ​​differing from the negative / positive pipe pressure drop values; the positive / negative pipe pressure drop values ​​being less than the third threshold and the negative / positive pipe pressure drop values ​​being undetectable; and the positive / negative pipe pressure drop values ​​being undetectable and the negative / positive pipe pressure drop values ​​being less than the third threshold. Normally, the third threshold is less than 1 volt.

[0096] Specifically, when current flows from one end of the busbar to the other (forward current), a voltage drop is generated due to the busbar resistance. The value of this voltage drop depends on the magnitude of the current and the resistance of the busbar. If the direction of the current changes (reverse current), theoretically, since the busbar resistance remains unchanged, the voltage drop should be the same as that under forward current conditions, i.e., the positive / negative tube voltage drop should be the same as the negative / positive tube voltage drop. However, if the positive / negative tube voltage drop is different from the negative / positive tube voltage drop, it is considered an abnormality in the voltage drop value, thus indicating whether a pre-charge fault has occurred in the high-voltage component.

[0097] Based on the electric vehicle fault diagnosis system 1, an embodiment of the present invention provides a method for diagnosing insulation faults in electric vehicles. In this embodiment, the insulation fault diagnosis judgment condition is:

[0098] After detecting an insulation resistance value less than a first preset value and reading the insulation fault code, it is determined that the first insulation fault troubleshooting mode has been satisfied. Based on the action feedback information of the read insulation fault code, it is determined whether a power battery insulation fault or a high-voltage component insulation fault has occurred; and,

[0099] After detecting that the insulation resistance value is less than the second preset value and no insulation fault code is read, it is determined that the second insulation fault troubleshooting mode is satisfied. Based on the action feedback information of the read insulation resistance value, it is determined whether a power battery insulation fault or a high-voltage component insulation fault has occurred.

[0100] In this embodiment, the first insulation fault is when the insulation resistance is less than a preset threshold and an insulation fault is reported, and the second insulation fault is when the insulation resistance is less than the preset threshold and no insulation fault is reported.

[0101] In the insulation fault troubleshooting method where the insulation resistance is less than the preset threshold and the first insulation fault troubleshooting mode is met, the action feedback information of the read insulation fault code, i.e. whether the insulation fault code can be reproduced, is used to determine whether it is a power battery insulation fault or a high-voltage component insulation fault.

[0102] The specific troubleshooting methods for insulation resistance values ​​less than a preset threshold and an insulation fault report are as follows:

[0103] Step 1: Under the high voltage and electrical control conditions of the whole vehicle, read the insulation resistance value and the first insulation fault code. After clearing the first insulation fault code, read the second insulation fault code. If the second insulation fault code is the same as the first insulation fault code, it is determined to be a power battery insulation fault.

[0104] Step 2: If the second insulation fault code is not read, disable the vehicle controller in the electric vehicle fault diagnosis system and control the main positive relay and main negative relay in the electric vehicle fault diagnosis system 1 to close.

[0105] Step 3: Read the insulation fault code and insulation resistance value, and check if the overall vehicle insulation resistance value is less than the preset threshold and if an insulation fault code is found. If so, proceed to Step 4.

[0106] Step 4: Clear the insulation fault code. After a period of time, disconnect the first high-voltage relay 211. After another period of time, check if the insulation fault code reappears. If the insulation fault code still appears, proceed to Step 5.

[0107] Step 5: Clear the insulation fault code. Sequentially disconnect the high-voltage relay 211 and read the insulation fault code and insulation resistance value after each disconnection of the high-voltage relay 211 until no insulation fault code appears and / or the insulation resistance value is within the preset threshold. Output the fault type of the electric vehicle as the insulation fault of the high-voltage component of the electric vehicle corresponding to the high-voltage relay 211 when the insulation fault code disappears and the insulation resistance value is within the preset threshold.

[0108] In step two, if the high-voltage interlock failure function of the vehicle controller is not disabled, the vehicle will malfunction and alarm once the main positive relay and the main negative relay are closed. In order to find out which high-voltage component 212 is faulty, the high-voltage interlock failure function of the vehicle controller needs to be disabled first, and then the closing steps of the main positive relay and the main negative relay are executed. In this way, the corresponding high-voltage component 212 fault can be identified by disconnecting the high-voltage relay 211.

[0109] By sequentially closing high-voltage relay 211, insulation faults can be gradually identified and located. Maintenance personnel can quickly find and repair faulty components, thereby restoring the normal operation of the electric vehicle.

[0110] In the method of troubleshooting insulation faults where the insulation resistance value is less than the preset threshold and no insulation fault is reported, i.e. when the second insulation fault troubleshooting mode is met, the action feedback information of the read insulation resistance value, i.e. whether the insulation resistance value can be reproduced, is used to determine whether a power battery insulation fault or a high-voltage component insulation fault has occurred.

[0111] Specific troubleshooting methods for insulation resistance values ​​less than a preset threshold that do not report insulation faults include:

[0112] Step 1: Under the high-voltage electrical control conditions of the whole vehicle, read the first insulation resistance value and insulation fault code, and determine whether the first insulation resistance value is less than the preset threshold and no insulation fault code appears;

[0113] Step 2: When the first insulation resistance value is less than the preset threshold and no insulation fault code appears, clear the first insulation resistance value and read the second insulation resistance value. If the second insulation resistance value is less than the preset threshold and no insulation fault code appears, it is determined to be a power battery insulation fault.

[0114] Step 3: If no insulation resistance value is detected after clearing the insulation resistance value, then the insulation resistance value reproduction action is executed. Each high-voltage relay 211 is closed sequentially until the detected insulation resistance value meets the second preset value. It is then determined that the corresponding high-voltage component 212 has a high-voltage component insulation fault. The insulation resistance value reproduction action includes operating the secondary insulation detection module in the electric vehicle fault diagnosis system 1.

[0115] In steps one and two, by comparing the insulation resistance values, if the second insulation resistance value is the same as the first insulation resistance value, it indicates that there is a fault in the power battery where the insulation resistance value is too low, and it needs to be repaired.

[0116] Low insulation resistance of power battery may be caused by a variety of reasons: internal battery structure problems, battery short circuit, installation problems or system vibration. Repair is required to ensure the safe and reliable operation of the electric vehicle's high-voltage system.

[0117] In step three, the insulation resistance value reproduction action specifically includes activating the secondary insulation detection module, injecting insulation detection voltage into the busbar through the boost chopper circuit, and reading the insulation resistance value.

[0118] When a problem is suspected in the insulation performance of high-voltage component 212, the secondary insulation detection module is activated. The secondary insulation detection module injects a specific insulation detection voltage into the high-voltage bus outside the power battery through a boost chopper circuit. This voltage is usually higher than the normal operating voltage in order to more accurately detect the performance of the insulation layer. After the insulation detection voltage is injected, the insulation resistance value fed back by the secondary insulation detection module is read. This resistance value reflects the current insulation status of high-voltage component 212.

[0119] The insulation resistance value is compared with the preset threshold. If the insulation resistance value is less than the threshold, it indicates that there is a problem with the insulation performance of the high-voltage component 212 and further investigation is required. In order to determine the specific component that causes the insulation resistance value to be low, the high-voltage relay 211 needs to be disconnected step by step, and the insulation resistance value is read after each disconnection. The purpose of this step is to find the high-voltage component 212 that causes the insulation resistance value to be low through step-by-step investigation.

[0120] The insulation resistance value is continuously read until it reaches the preset threshold. This indicates that the high-voltage component 212 causing the low insulation resistance value has been found and the fault has been eliminated by disconnecting the corresponding high-voltage relay 211.

[0121] Specifically, by determining which high-voltage relay 211, after which the insulation resistance returned to normal, the high-voltage component 212 causing the insulation fault can be identified. Based on the type and location of the output fault, maintenance personnel can take appropriate measures to repair or replace the faulty component. For example, if it is determined that the fault is caused by damage to the insulation layer of a high-voltage cable, then that cable needs to be replaced.

[0122] One embodiment of the present invention provides an electric vehicle fault diagnosis system. For details, please refer to [link / reference]. Figure 3 , Figure 3 The diagram shows an electric vehicle pre-charging and insulation fault diagnosis system according to one embodiment of the present invention.

[0123] The electric vehicle pre-charge and insulation fault detection system includes an insulation and pre-charge fault detection unit 4, a battery management system 5 controlled by the insulation and pre-charge fault detection unit 4, and several high-voltage relays.

[0124] The battery management system 5 includes a precharge detection module 3, a secondary insulation detection module 6, a main positive relay 7, and a main negative relay 8;

[0125] The detection terminal of the secondary insulation detection module 6 is connected to the positive terminal of the electric vehicle bus 9 through the main positive relay 7. The detection terminal of the secondary insulation detection module 6 is also connected to the negative terminal of the electric vehicle bus 9 through the main negative relay 8. The power supply terminal of the secondary insulation detection module 6 is connected to the external electric vehicle battery system. The secondary insulation detection module 6 is used to control the selected high-voltage relay to realize the investigation of insulation faults in high-voltage components.

[0126] The insulation and precharge fault detection unit 4 (FDU) serves as the central hub for insulation and precharge fault detection. It communicates and controls the BMS, precharge detection module 3, secondary insulation detection module 6, high-voltage relays of various high-voltage components, and vehicle controller (VCU) through the vehicle communication network. The communication network can be CAN communication or LIN communication, etc.

[0127] The insulation and precharge fault detection unit 4 (FDU) has the function of communicating with the vehicle remote terminal, thereby exchanging data with the automotive after-sales maintenance cloud platform through the vehicle remote terminal. The after-sales maintenance cloud platform can also realize remote troubleshooting of insulation and precharge faults in the vehicle. At the same time, the insulation and precharge fault detection unit 4 (FDU) has the function of clearing fault codes related to insulation and precharge failures in various high-voltage controllers and vehicle controllers of electric vehicles.

[0128] The insulation and precharge fault detection unit 4 (FDU) has the function of shielding the high-voltage interlock failure of the vehicle controller (VCU) or controlling the BMS to open and close the main positive (K positive) relay 7 and the main negative (K negative) relay 8 of the power battery when the vehicle controller (VCU) reports a high-voltage interlock failure.

[0129] The electric vehicle pre-charge and insulation fault detection system also includes a vehicle controller, which is controlled by the insulation and pre-charge fault detection unit 4.

[0130] The vehicle control unit (VCU), as the central control unit of a new energy vehicle, is the core of the entire control system. The VCU collects motor and battery status data (usually through CAN or LIN communication, directly interacting with the battery management system). It also collects accelerator pedal signals, brake pedal signals, actuator and sensor signals through its own I / O ports. Based on the driver's intentions, it comprehensively analyzes and makes corresponding judgments, then monitors the actions of lower-level component controllers. It is responsible for normal vehicle operation, regenerative braking, energy management of the vehicle's drive system and power battery, network management, fault diagnosis and handling, and vehicle status monitoring, thereby ensuring the vehicle operates normally and stably with good power, high economy, and high reliability.

[0131] The secondary insulation detection module 6 can monitor the insulation resistance value of power equipment in real time and predict the trend of insulation faults through data analysis. Once the insulation resistance value is detected to be too low, the module will issue an alarm message to remind the user or vehicle control system to carry out maintenance.

[0132] In the operation of the battery management system 5, the main positive relay 7 and the main negative relay 8 control the connection and disconnection of the positive and negative circuits of the battery pack, ensuring the safe, stable and efficient operation of the battery pack.

[0133] In electric vehicles, each high-voltage component corresponds to a high-voltage relay (K1, K2, ..., Kn). The high-voltage relay acts as a controlled switch, precisely controlling the on / off state of each high-voltage component. When a high-voltage component needs to operate, the corresponding high-voltage relay closes, allowing current to flow; when the component is not needed, the relay opens, cutting off the current. Simultaneously, the high-voltage relay can also serve as a starting point for troubleshooting.

[0134] Specifically, high-voltage components mainly include drive motors, high-voltage distribution boxes, electric compressors, on-board chargers, and motor controllers. These are just illustrative examples; the specific high-voltage components depend on the specific electric vehicle.

[0135] The electric vehicle pre-charging and insulation fault diagnosis system can diagnose three types of faults: pre-charging fault diagnosis, diagnosis of electric vehicle insulation resistance value less than preset threshold and reporting insulation fault, and diagnosis of insulation resistance value less than preset value and not reporting insulation fault.

[0136] One embodiment of the present invention provides a method for troubleshooting electric vehicle faults. For details, please refer to [link / reference]. Figure 4 , Figure 4 The diagram shown is a flowchart of a pre-charging fault diagnosis method based on an electric vehicle pre-charging and insulation fault diagnosis system, according to one embodiment of the present invention. The method includes:

[0137] S11: After the control insulation and precharge fault detection unit disconnects all high-voltage relays, the control insulation and precharge fault detection unit reads the insulation fault code. When the insulation and precharge fault detection unit reads the insulation fault code, detects an abnormal voltage in the power battery, or detects an abnormal insulation resistance, it is determined to be an internal precharge fault of the power battery.

[0138] S12: When the insulation and precharge fault detection unit does not read the insulation fault code, does not detect the abnormal voltage inside the power battery, or does not detect the abnormal insulation resistance, control the insulation and precharge fault detection unit to start the precharge detection module to determine the electric vehicle bus resistance value and / or pipe voltage drop value.

[0139] S13: Control insulation and precharge fault detection unit reads the feedback result of the precharge detection module after each closing of the high-voltage relay until the precharge detection module detects abnormal resistance value and / or pipe voltage drop value of the electric vehicle bus. Based on the resistance value and / or pipe voltage drop value of the electric vehicle bus, output the electric vehicle fault type as the electric vehicle high-voltage component precharge fault corresponding to the high-voltage relay when the resistance value and / or pipe voltage drop value of the electric vehicle bus is abnormal.

[0140] Before step S11, under the condition of high-voltage power-on control of the whole vehicle, the insulation and pre-charge fault detection unit 4 needs to read the pre-charge fault code fed back by the battery management system 5. By reading the pre-charge fault code, the insulation and pre-charge fault detection unit 4 can quickly locate the fault point. Then, under the condition of high-voltage power-off control of the whole vehicle, after the insulation and pre-charge fault detection unit 4 clears the pre-charge fault code, the insulation and pre-charge fault detection unit 4 disconnects all high-voltage relays. Clearing the pre-charge fault code when the high voltage is off is to ensure that the system will not misjudge or affect normal operation due to the previous fault code when the next power is on.

[0141] In other words, the operation of the control insulation and pre-charge fault detection unit 4 during the high-voltage power-on and power-off control process of the whole vehicle is to ensure the safety, stability and reliability of the high-voltage system.

[0142] In S12 and S13, the faulty high-voltage component of the electric vehicle is identified by judging the resistance value and / or the voltage drop value of the electric vehicle bus 9.

[0143] Abnormal resistance values ​​of the electric vehicle bus 9 include any one of the following: the positive / negative resistance values ​​differ from the negative / positive resistance values; the ratio of the positive / negative resistance values ​​to the negative / positive resistance values, or the ratio of the negative / positive resistance values ​​to the positive / negative resistance values, is greater than a first threshold; or the positive / negative resistance values ​​and the negative / positive resistance values ​​are greater than a second threshold. Typically, the first threshold is greater than 1000, and the second threshold is greater than 2 megohms.

[0144] Abnormal pipe pressure drop conditions include any of the following: the positive / negative pipe pressure drop values ​​differ from the negative / positive pipe pressure drop values; the positive / negative pipe pressure drop values ​​are less than the third threshold and the negative / positive pipe pressure drop values ​​cannot be detected; or the positive / negative pipe pressure drop values ​​cannot be detected and the negative / positive pipe pressure drop values ​​are less than the third threshold. Normally, the third threshold is less than 1 volt.

[0145] Specifically, the pre-charge fault troubleshooting method includes the following steps:

[0146] Step 1: Under the condition of vehicle high-voltage power-on control, the normal operation is to turn the key to the On position and press the foot brake pedal. The insulation and pre-charge fault detection unit 4 reads the fault codes detected by the battery management system 5 to check if there is a pre-charge fault code. If there is, proceed to Step 2 under the condition of vehicle high-voltage power-off control.

[0147] Step Two: The insulation and pre-charge fault detection unit 4 sends an instruction to the battery management system 5 to clear the vehicle's pre-charge fault codes. After a period of time, all high-voltage component relays are disconnected. Under the vehicle's high-voltage power-on control condition, the insulation and pre-charge fault detection unit 4 reads the voltage, insulation resistance, and fault codes inside the power battery. If the voltage or insulation resistance inside the power battery is abnormal, or if an insulation fault code appears, the insulation and pre-charge fault detection unit 4 determines that there is an internal pre-charge fault in the power battery. If no abnormality occurs, proceed to Step Three.

[0148] Step 3: Insulation and pre-charge fault detection unit 4 starts pre-charge detection module 3 to determine the resistance value and / or pipe voltage drop value of electric vehicle bus 9;

[0149] Step 4: Control insulation and precharge fault detection unit 4 reads the feedback result of precharge detection module 3 after each closing of high voltage relay until precharge detection module 3 detects abnormal resistance value and / or pipe voltage drop value of electric vehicle bus 9. Based on the resistance value and / or pipe voltage drop value of electric vehicle bus 9, output the fault type of electric vehicle as precharge fault of electric vehicle high voltage component corresponding to high voltage relay when the resistance value and / or pipe voltage drop value of electric vehicle bus 9 is abnormal.

[0150] The rules for determining abnormal resistance and voltage drop are as follows:

[0151] Abnormal resistance values ​​of the electric vehicle bus 9 include any of the following: the positive / negative resistance values ​​differ from the negative / positive resistance values; the ratio of the positive / negative resistance values ​​to the negative / positive resistance values, or the ratio of the negative / positive resistance values ​​to the positive / negative resistance values, is greater than a first threshold; or the positive / negative resistance values ​​and the negative / positive resistance values ​​are greater than a second threshold. Typically, the first threshold is greater than 1000, and the second threshold is greater than 2 megohms.

[0152] Abnormal pipe pressure drop conditions include any of the following: the positive / negative pipe pressure drop values ​​differ from the negative / positive pipe pressure drop values; the positive / negative pipe pressure drop values ​​are less than the third threshold and the negative / positive pipe pressure drop values ​​cannot be detected; or the positive / negative pipe pressure drop values ​​cannot be detected and the negative / positive pipe pressure drop values ​​are less than the third threshold. Normally, the third threshold is less than 1 volt.

[0153] One embodiment of the present invention provides a method for troubleshooting pre-charging faults in electric vehicles. For details, please refer to [link / reference]. Figure 5 , Figure 5 The diagram shows a flowchart of a method for troubleshooting an electric vehicle insulation resistance value less than a preset threshold and reporting an insulation fault, based on an electric vehicle pre-charging and insulation fault detection system, according to one embodiment of the present invention. The method includes:

[0154] S21: Under the high voltage power control conditions of the whole vehicle, the control insulation and precharge fault detection unit reads the first insulation fault code fed back by the battery management system. After clearing the first insulation fault code, the control insulation and precharge fault detection unit reads the second insulation fault code. If the second insulation fault code is the same as the first insulation fault code, it is determined to be a power battery insulation fault.

[0155] S22: When the insulation and precharge fault detection unit does not read the second insulation fault code, the vehicle controller is disabled, and the main positive relay and the main negative relay are closed.

[0156] S23: Sequentially disconnect the high-voltage relays, control the insulation and pre-charge fault detection unit to read the insulation fault code and insulation resistance value fed back by the battery management system after each disconnection of the high-voltage relay, until the insulation fault code disappears and the insulation resistance value is within the preset threshold, and output the fault type of the electric vehicle as the insulation fault of the high-voltage component of the electric vehicle corresponding to the high-voltage relay when the insulation fault code disappears and the insulation resistance value is within the preset threshold.

[0157] In step S21, by comparing the second insulation fault code with the first insulation fault code, if the second insulation fault code is the same as the first insulation fault code, it usually means that there is a continuous insulation fault in the power battery. This process is an important part of the electric control process under high voltage in electric vehicles. By reading and comparing the insulation fault codes, insulation faults in the power battery system can be detected and dealt with in a timely manner, ensuring the safety and reliability of electric vehicles.

[0158] During step S22, after ensuring the vehicle controller is shielded, close the main positive relay 7 and the main negative relay 8. These two relays are key components connecting the power battery and the high-voltage load; their closure will allow the high-voltage system to be re-energized for further troubleshooting.

[0159] In step S22, if the high-voltage interlock failure function of the vehicle controller is not disabled, the vehicle will malfunction and alarm once the main positive relay 7 and the main negative relay 8 are closed. In order to find out which high-voltage component is faulty, the high-voltage interlock failure function of the vehicle controller needs to be disabled first, and then the closing steps of the main positive relay 7 and the main negative relay 8 are executed. In this way, the corresponding high-voltage component fault can be identified by disconnecting the high-voltage relay.

[0160] By sequentially closing high-voltage relays to gradually identify and locate insulation faults, maintenance personnel can quickly find and repair faulty components, thereby restoring the normal operation of electric vehicles.

[0161] Specifically, the troubleshooting method for insulation resistance values ​​less than a preset threshold and an insulation fault report includes the following steps:

[0162] Step 1: Under the high-voltage power control condition of the whole vehicle, the insulation and pre-charge fault detection unit 4 reads the insulation fault code detected by the battery management system 5 and checks whether there is an insulation resistance value less than the preset threshold. If so, proceed to step 2.

[0163] Step 2: The insulation and pre-charge fault detection unit 4 sends an instruction to the battery management system 5 to clear the insulation fault code. After a period of time, the insulation and pre-charge fault detection unit 4 reads the insulation fault code fed back by the battery management system 5. If the insulation fault code is the same as that in Step 1, the insulation and pre-charge fault detection unit 4 determines that it is a power battery insulation fault. If the above abnormality does not occur, proceed to Step 3.

[0164] Step 3: The insulation and pre-charge fault detection unit 4 shields the vehicle controller and controls the main positive relay 7 and the main negative relay 8 to close;

[0165] Step 4: The insulation and pre-charge fault detection unit 4 reads the insulation fault code and insulation resistance value fed back by the battery management system 5, and checks whether the insulation resistance value of the whole vehicle is less than the preset threshold and the insulation fault code. If so, proceed to step 5.

[0166] Step 5: The insulation and pre-charge fault detection unit 4 sends a command to the battery management system 5 to clear the insulation fault code. After a period of time, the insulation and pre-charge fault detection unit 4 controls the disconnection of the first high-voltage relay. After a period of time, it checks whether an insulation fault code appears. If an insulation fault code still appears, proceed to step 6.

[0167] Step Six: The insulation and pre-charge fault detection unit 4 sends an instruction to the battery management system 5 to clear the insulation fault code. The insulation and pre-charge fault detection unit 4 reads the insulation fault code and insulation resistance value fed back by the battery management system 5 after each closing of the high-voltage relay until the insulation fault code disappears and the insulation resistance value is within the preset threshold. The fault type of the electric vehicle is output as the insulation fault of the high-voltage component of the electric vehicle corresponding to the high-voltage relay when the insulation fault code disappears and the insulation resistance value is within the preset threshold.

[0168] One embodiment of the present invention provides a method for troubleshooting pre-charging faults in electric vehicles. For details, please refer to [link / reference]. Figure 6 , Figure 6 The diagram shows a flowchart of a method for troubleshooting an electric vehicle whose insulation resistance is less than a preset threshold and which does not report an insulation fault, based on an electric vehicle pre-charging and insulation fault troubleshooting system according to one embodiment of the present invention. The method includes:

[0169] S31: Under the high voltage control conditions of the whole vehicle, the control insulation and precharge fault detection unit reads the first insulation resistance value fed back by the battery management system and determines whether the first insulation resistance value is less than the preset threshold and whether no insulation fault code appears.

[0170] S32: When the insulation and precharge fault detection unit detects that the first insulation resistance value is less than the preset threshold and no insulation fault code appears, refresh the first insulation resistance value and control the insulation and precharge fault detection unit to read the second insulation resistance value fed back by the battery management system. If the second insulation resistance value is less than the preset threshold and no insulation fault code appears, it is determined to be a power battery insulation fault.

[0171] S33: After starting the secondary insulation detection module, the insulation detection voltage is injected into the electric vehicle bus through the boost chopper circuit, and the insulation and pre-charge fault detection unit is controlled to read the insulation resistance value fed back by the secondary insulation detection module. Then, the high-voltage relays are disconnected in sequence. When the insulation resistance value is less than the preset threshold, the insulation and pre-charge fault detection unit is controlled to read the insulation resistance value fed back by the battery management system after each disconnection of the high-voltage relay, until the insulation fault code disappears and the insulation resistance value is within the preset threshold. The fault type of the electric vehicle is output as the insulation fault of the high-voltage component of the electric vehicle corresponding to the high-voltage relay when the insulation fault code disappears and the insulation resistance value is within the preset threshold.

[0172] In steps S31 and S32, by comparing the insulation resistance values, if the second insulation resistance value is the same as the first insulation resistance value, it indicates that there is a fault of low insulation resistance value of the power battery, and it needs to be repaired.

[0173] Low insulation resistance of power battery may be caused by a variety of reasons: internal battery structure problems, battery short circuit, installation problems or system vibration. Repair is required to ensure the safe and reliable operation of the electric vehicle's high-voltage system.

[0174] In step S33, when a problem with the insulation performance of the power battery is suspected, the secondary insulation detection module 6 is activated. The secondary insulation detection module 6 injects a specific insulation detection voltage into the electric vehicle bus 9 through a boost chopper circuit. This voltage is usually higher than the normal operating voltage in order to more accurately detect the performance of the insulation layer. After the insulation detection voltage is injected, the insulation and precharge fault detection unit 4 reads the insulation resistance value fed back by the secondary insulation detection module 6. This resistance value reflects the current insulation state of the power battery system.

[0175] The insulation resistance value is compared with the preset threshold. If the insulation resistance value is less than the threshold, it indicates that there is a problem with the insulation performance of the power battery and further investigation is required. In order to determine the specific component that causes the insulation resistance value to be low, the high voltage relay needs to be disconnected step by step, and the insulation resistance value fed back by the battery management system 5 is read after each disconnection. The purpose of this step is to find the component that causes the insulation resistance value to be low through step-by-step investigation.

[0176] Continuously read the insulation resistance value until it reaches the preset threshold. This indicates that the component causing the low insulation resistance value has been found and the fault has been eliminated by disconnecting the corresponding high-voltage relay.

[0177] Once the component causing the low insulation resistance is identified, the insulation and pre-charge fault detection unit 4 will output the fault type and location. Specifically, it will indicate the moment the high-voltage relay was disconnected after which the insulation resistance returned to normal, thus identifying the high-voltage component causing the insulation fault. Based on the output fault type and location, maintenance personnel can take appropriate measures to repair or replace the faulty component. For example, if it is determined that the fault is caused by damage to the insulation layer of a high-voltage cable, then that cable needs to be replaced.

[0178] Specifically, the troubleshooting method for insulation resistance values ​​less than a preset threshold that do not report insulation faults includes the following steps:

[0179] Step 1: Under the high-voltage power control condition of the whole vehicle, the insulation and pre-charge fault detection unit 4 reads the insulation fault code and insulation resistance value detected by the battery management system 5 and checks whether there is an insulation resistance value less than the preset threshold. If so, proceed to step 2.

[0180] Step 2: The insulation and precharge fault detection unit 4 sends an instruction to the battery management system 5 to refresh the insulation resistance value. After a period of time, the insulation and precharge fault detection unit 4 reads the insulation resistance value fed back by the battery management system 5 and confirms whether the insulation resistance value is less than the preset threshold. If the insulation resistance value is less than the preset threshold and no insulation fault code appears, the insulation and precharge fault detection unit 4 determines that the power battery insulation is faulty. If the above abnormality does not occur, proceed to step 3.

[0181] Step 3: The insulation and pre-charge fault detection unit 4 activates the secondary insulation detection module 6. Through a boost chopper circuit, it injects insulation detection voltage into the busbar and controls the insulation and pre-charge fault detection unit 4 to read the insulation resistance value fed back by the secondary insulation detection module 6. Then, it confirms whether the actual insulation resistance value of the entire vehicle is less than the preset threshold. If the measured insulation resistance value is less than the preset threshold, proceed to Step 4.

[0182] Step 4: The insulation and pre-charge fault detection unit 4 controls the disconnection of the first high-voltage relay. After a period of time, it checks whether the insulation resistance value is less than the preset threshold. If the insulation resistance value is still less than the preset threshold, proceed to step 5.

[0183] Step 5: Control the insulation and pre-charge fault detection unit 4 to read the insulation resistance value fed back by the battery management system 5 after each disconnection of the high-voltage relay, until the insulation fault code disappears and the insulation resistance value is within the preset threshold, and output the fault type of the electric vehicle as the insulation fault code disappears and the insulation resistance value is within the preset threshold when the high-voltage relay corresponds to the high-voltage component of the electric vehicle experiencing an insulation fault.

[0184] One embodiment of the present invention provides an electric vehicle, which includes any electric vehicle fault diagnosis system or an electric vehicle for implementing any of the electric vehicle fault diagnosis methods described herein.

[0185] Specifically, electric vehicles can be categorized into pure electric vehicles, hybrid electric vehicles, and fuel cell vehicles. Pure electric vehicles are vehicles that are entirely powered by electricity, hybrid electric vehicles combine two power sources: an internal combustion engine and an electric motor, while fuel cell vehicles use fuel cells to generate electricity to drive the vehicle.

[0186] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for troubleshooting electric vehicle faults, characterized in that, The electric vehicle fault diagnosis system includes a pre-charge detection module and a pre-charge detection circuit module connected in parallel to the electric vehicle bus. The pre-charge detection circuit module includes several parallel pre-charge detection branches. Each pre-charge detection branch is connected to the electric vehicle bus, and each pre-charge detection branch includes a high-voltage component and a high-voltage relay for controlling the on / off state of the current pre-charge detection branch. The detection end of the precharge detection module is connected to the electric vehicle bus, and the power supply end of the precharge detection module is connected to the electric vehicle battery system. The precharge detection module is used to troubleshoot precharge faults of the high-voltage component corresponding to the high-voltage relay based on the resistance value and / or voltage drop value of the electric vehicle bus. The electric vehicle fault diagnosis method includes: When a precharge fault code is detected, the system enters the precharge fault troubleshooting mode. Based on the detected power battery voltage and insulation resistance values ​​of the electric vehicle battery system, determine whether an internal pre-charge fault has occurred in the power battery. When the fault is not due to an internal pre-charge fault of the power battery, the resistance value and / or voltage drop value of the electric vehicle bus are used to determine whether a high-voltage component pre-charge fault has occurred. After disconnecting all the high-voltage relays, if an insulation fault code is read, an abnormal voltage is detected in the power battery, or an abnormal insulation resistance is detected, it is determined that an internal pre-charge fault has occurred in the power battery. The pre-charge detection module is activated when no insulation fault code is read, no abnormal voltage is detected in the power battery, or no abnormal insulation resistance is detected. After the pre-charge detection module is started, each of the high-voltage relays is closed in sequence, and the feedback result of the pre-charge detection module after each closure is read, until the pre-charge detection module detects that the resistance value and / or the pipe voltage drop value of the electric vehicle bus is abnormal. When an abnormality is detected in the resistance value and / or the voltage drop value of the electric vehicle bus, it is determined that the corresponding high-voltage component has a pre-charge fault.

2. The electric vehicle fault diagnosis method as described in claim 1, characterized in that, The electric vehicle fault diagnosis system also includes a secondary insulation detection module, a main positive relay, and a main negative relay; The detection terminal of the secondary insulation detection module is connected to the positive terminal of the electric vehicle bus via the main positive relay. The detection terminal of the secondary insulation detection module is also connected to the negative terminal of the electric vehicle bus via the main negative relay. The power supply terminal of the secondary insulation detection module is connected to the external electric vehicle battery system. The secondary insulation detection module is used to control the selected high-voltage relay to detect insulation faults in the high-voltage components.

3. The electric vehicle fault diagnosis method as described in claim 1, characterized in that, Before disconnecting all the high-voltage relays, the electric vehicle fault diagnosis method further includes: Under the condition of high-voltage power-on control of the whole vehicle, read the pre-charge fault code; Under the high-voltage power control conditions of the whole vehicle, after clearing the pre-charge fault code, disconnect all the high-voltage relays.

4. The electric vehicle fault diagnosis method as described in claim 1, characterized in that, Abnormal resistance values ​​of the electric vehicle bus include any one of the following: positive / negative resistance values ​​are different from negative / positive resistance values; the ratio of positive / negative resistance values ​​to negative / positive resistance values ​​or the ratio of negative / positive resistance values ​​to positive / negative resistance values ​​is greater than a first threshold; and the positive / negative resistance values ​​and negative / positive resistance values ​​are greater than a second threshold. The abnormal conditions of the pipe pressure drop value include any one of the following: the positive / negative pipe pressure drop value is different from the negative / positive pipe pressure drop value; the positive / negative pipe pressure drop value is less than the third threshold and the negative / positive pipe pressure drop value cannot be detected; the positive / negative pipe pressure drop value cannot be detected and the negative / positive pipe pressure drop value is less than the third threshold value.

5. The electric vehicle fault diagnosis method as described in claim 1, further comprising: After detecting that the insulation resistance is less than the preset threshold and reading the insulation fault code, it is determined that the first insulation fault troubleshooting mode is satisfied. Based on the action feedback information of the read insulation fault code, it is determined whether a power battery insulation fault or a high-voltage component insulation fault has occurred. and, After detecting that the insulation resistance value is less than the preset threshold and no insulation fault code is read, it is determined that the second insulation fault troubleshooting mode is satisfied. Based on the action feedback information of the read insulation resistance value, it is determined whether a power battery insulation fault or a high-voltage component insulation fault has occurred.

6. The electric vehicle fault diagnosis method as described in claim 5, characterized in that, The determination that the first insulation fault investigation mode is satisfied, based on the action feedback information of the read insulation fault code, determines whether a power battery insulation fault or a high-voltage component insulation fault has occurred, including: When the first insulation fault investigation mode is met, if the insulation fault code is detected to reappear after being cleared, then the type of insulation fault is determined to be the power battery insulation fault; and, When the first insulation fault investigation mode is met, if no insulation fault code is detected to reappear after clearing the insulation fault code, an insulation fault code reappearance action is performed, and each of the high-voltage relays is disconnected in sequence until no reappearance of the insulation fault code is detected and / or the insulation resistance value is detected to meet the preset threshold. It is then determined that the corresponding high-voltage component has an insulation fault. The insulation fault code reappearance action includes shielding the vehicle controller and controlling the main positive relay and the main negative relay in the electric vehicle fault investigation system to close.

7. The electric vehicle fault diagnosis method as described in claim 5, characterized in that, The determination that the second insulation fault investigation mode is satisfied is based on the action feedback information of the read insulation resistance value, and it is determined whether a power battery insulation fault or a high-voltage component insulation fault has occurred, including: When the second insulation fault investigation mode is met, if the insulation resistance value is detected to reappear after being cleared, then the type of insulation fault is determined to be the power battery insulation fault; and, When the second insulation fault investigation mode is met, if the insulation resistance value is not detected to reappear after clearing the insulation resistance value, the insulation resistance value reappearance action is executed, and each of the high-voltage relays is closed in sequence until the detected insulation resistance value meets the preset threshold. It is then determined that the high-voltage component currently has an insulation fault. The insulation resistance value reappearance action includes operating the secondary insulation detection module in the electric vehicle fault investigation system.

Images