Method for identifying contactor fault based on contactor front and rear end voltage method

Abstract

The invention discloses a contactor fault identification method based on a contactor front and rear end voltage method, and relates to the technical field of contactor fault identification. The main loop pre-charging state is divided into a pre-detection state, a pre-charging contactor closing state, a main contactor closing state, a pre-charging contactor opening state, a main contactor closing state and a pre-charging overtime state; in the pre-detection state, if the front end voltage of the main contactor is larger than 380V, adhesion logic detection is carried out; if not, disconnecting the contactor and resetting the main counter; when the pre-charging contactor is closed, the circuit state is judged according to voltage and time; after the main contactor is closed, the delay counter is started to ensure that the circuit is stable; after pre-charging is completed, a counter and fault records are cleared; if the pre-charging is overtime, the contactor is disconnected, the counter is reset, and the fault is activated; in addition, the pre-detection state further comprises special condition processing logic, so that the circuit safety is ensured. According to the invention, the fault state of the contactor is detected by monitoring the voltage change of the main loop in different pre-charging states, and the driving safety is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of contactor fault identification, and in particular, relates to a method for identifying contactor faults based on a contactor front and rear end voltage method. Background Art

[0002] At present, in the all-in-one controller of new energy heavy-duty trucks, fault identification of high-power contactors is a difficult point. The TM1 output port of the all-in-one controller is connected to the bus support capacitor of the motor controller, so the bus support capacitor needs to be pre-charged. The pre-charging circuit is usually composed of a main contactor and a pre-charging contactor, which interferes with the judgment of the adhesion fault of the main contactor. In addition, during the process of powering off the entire vehicle, the motor controller has a rapid discharge process, which also interferes with the judgment of the adhesion fault of the main contactor.

[0003] If a main contactor with an auxiliary contact mechanical structure is used, it is a better method to use the feedback status of the auxiliary contact to identify the fault of the main contactor. However, in the actual field application of the all-in-one product, it is found that the auxiliary contact mechanical structure of the main contactor of the main circuit is damaged due to excessive temperature, which affects the judgment logic of the software. On the other hand, the damage to the auxiliary contact mechanical structure will also cause the main contact of the main contactor to be abnormally disconnected during normal driving, posing a hidden danger to driving safety. Summary of the invention

[0004] The purpose of this application is to provide a method for identifying contactor faults based on the front and rear end voltage method of the contactor, and to detect the fault state of the contactor by monitoring the voltage changes of the main circuit under different pre-charging states.

[0005] In order to achieve the above object, the embodiment of the present application provides a method for identifying contactor faults based on the front and rear end voltage method of the contactor, comprising:

[0006] Obtain the main circuit pre-charging status, which includes pre-check status, pre-charging contactor closing status, main contactor closing status, pre-charging contactor disconnected and main contactor closed status, and pre-charging timeout status;

[0007] When the pre-charge state of the main circuit is the pre-check state, determine whether the front-end voltage of the main contactor is greater than 380V. If the front-end voltage of the main contactor is greater than 380V, perform the main contactor adhesion logic detection to determine whether the main contactor adhesion fault is activated. If the main contactor adhesion fault is activated, maintain the current state; if the main contactor adhesion fault is not activated, jump to the pre-charge contactor closed state; if the front-end voltage of the main contactor is not greater than 380V, disconnect the main contactor and the pre-charge contactor, and clear the main counter;

[0008] When the pre-charging state of the main circuit is the pre-charging contactor closed state, determine whether the front-end voltage of the main contactor is greater than 380V. If the front-end voltage of the main contactor is greater than 380V, start the pre-charging counter to determine whether the pre-charging counter time is greater than 2.7 seconds. If the pre-charging counter time is greater than 2.7 seconds, jump to the pre-charging timeout state; if the pre-charging counter time is not greater than 2.7 seconds, determine whether the rear-end voltage of the main contactor is greater than 0.9 times the front-end voltage of the main contactor. If the rear-end voltage of the main contactor is greater than 0.9 times the front-end voltage of the main contactor, jump to the main contactor closed state; if the rear-end voltage of the main contactor is not greater than 0.9 times the front-end voltage of the main contactor, end this round of identification; if the front-end voltage of the main contactor is not greater than 380V, disconnect the main contactor and the pre-charging contactor, and clear the pre-charging counter;

[0009] When the main circuit pre-charge state is the main contactor closed state, the delay counter is started to determine whether the delay counter time is greater than 0.5 seconds; if the delay counter time is greater than 0.5 seconds, it jumps to the pre-charge contactor disconnected and the main contactor closed state; if the delay counter time is not greater than 0.5 seconds, this round of identification ends;

[0010] When the pre-charging state of the main circuit is that the pre-charging contactor is disconnected and the main contactor is closed, all counters are cleared to clear the pre-charging failure fault. All counters include the main counter, pre-charging counter and delay counter;

[0011] When the pre-charging state of the main circuit is the pre-charging timeout state, the main contactor and the pre-charging contactor are disconnected, all counters are cleared, and the pre-charging failure fault is activated.

[0012] According to the above method of the embodiment of the present application, the following additional technical features may also be provided:

[0013] Furthermore, the main contactor sticking logic detection includes:

[0014] Determine whether the main circuit pre-charging is enabled by power on. If it is enabled by power on, clear the adhesion detection counter and restart the counting;

[0015] If it is not powered on, the auxiliary drive motor circuit is powered off with a delay, the adhesion detection counter and the cycle counter are cleared, and it is determined whether the voltage at the front end of the main contactor is greater than 10V and whether the voltage difference between the front and rear ends is less than 3V. If the voltage at the front end of the main contactor is greater than 10V and the voltage difference between the front and rear ends is less than 3V, the adhesion detection counter is incremented and it is determined whether the adhesion detection counter is greater than the preset threshold; if the voltage at the front end of the main contactor is not greater than 10V and the voltage difference between the front and rear ends is not less than 3V, the adhesion detection counter is cleared;

[0016] If the sticking detection counter is greater than the preset threshold, the main contactor sticking fault is activated; if the sticking detection counter is not greater than the preset threshold, the main contactor sticking fault is disabled.

[0017] Furthermore, when the pre-charging state of the main circuit is the pre-check state, the pre-check state is judged once every 10ms, and judged 20 times. In the pre-check state, both the pre-charging contactor and the main contactor are disconnected. If the voltage difference between the front and rear ends of the main contactor is less than 30V, it is judged that the main contactor has a adhesion fault, and the judgment of the next pre-charging contactor closing state will no longer be executed.

[0018] The method for identifying contactor faults based on the contactor front and rear voltage method provided by the embodiment of the present application has the following beneficial technical effects compared with the prior art:

[0019] The embodiment of the present application adopts a fault identification method based on the voltage method at the front and rear ends of the contactor, which can accurately determine the state of the main contactor and effectively distinguish between the normal state and the adhesion fault state even during the pre-charging process, thereby improving the accuracy of fault identification; by monitoring the voltage changes at the front and rear ends of the contactor, it can accurately identify the contactor state changes during the discharge process, thereby avoiding misjudgment caused by rapid discharge.

[0020] The embodiment of the present application does not rely on the state of the auxiliary contacts, but directly determines the fault by monitoring the voltage at the front and rear ends of the contactor, thereby avoiding misjudgment or missed judgment due to damage to the auxiliary contacts; the embodiment of the present application improves driving safety by monitoring the state of the main contactor in real time, promptly discovering and handling potential faults.

[0021] The embodiments of the present application can detect and handle faults in a timely manner by accurately monitoring and judging the state of the contactor, thereby avoiding shutdown or damage caused by failure to detect the fault in a timely manner. At the same time, since it does not depend on the state of the auxiliary contacts, it reduces the unstable factors caused by damage to the auxiliary contacts and enhances reliability and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a pre-check state flow chart of a method for identifying contactor faults based on a contactor front and rear end voltage method according to an embodiment of the present application is shown;

[0023] Figure 2 A schematic diagram of the closed state of the pre-charge contactor of the method for identifying contactor faults based on the contactor front and rear end voltage method according to an embodiment of the present application is shown;

[0024] Figure 3 A schematic diagram of the main contactor closing state process of the method for identifying contactor faults based on the contactor front and rear end voltage method according to an embodiment of the present application is shown;

[0025] Figure 4 A schematic flow chart of a state in which the pre-charge contactor is disconnected and the main contactor is closed in a method for identifying a contactor fault based on a contactor front and rear end voltage method according to an embodiment of the present application is shown;

[0026] Figure 5 A schematic diagram of a pre-charge timeout state flow chart of a method for identifying contactor faults based on a contactor front and rear end voltage method according to an embodiment of the present application is shown;

[0027] Figure 6 A schematic diagram of the main contactor sticking logic detection process of a method for identifying contactor faults based on the contactor front and rear end voltage method in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0030] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0031] An embodiment of the present application provides a method for identifying contactor faults based on the contactor front and rear end voltage method, wherein the main circuit pre-charging state includes a pre-check state, a pre-charging contactor closed state, a main contactor closed state, a pre-charging contactor disconnected and a main contactor closed state, and a pre-charging timeout state pre-check state.

[0032] Specifically, Figure 1As shown, when the main circuit pre-charging state is the pre-inspection state, it is first determined whether the front-end voltage of the main contactor is greater than 380V. This is a key voltage threshold judgment, which is used to determine whether to continue the subsequent adhesion logic detection or take other measures.

[0033] If the voltage at the front end of the main contactor is greater than 380V, the main contactor adhesion logic detection is performed. The adhesion logic detection is a complex judgment process, including judging whether the main circuit is powered on and enabled, delaying the power-off of the auxiliary drive motor circuit, judging the voltage and pressure difference, etc., to finally determine whether the main contactor has a adhesion fault.

[0034] If the main contactor sticking fault is active, the current state is maintained and no subsequent operations are performed. This means that if a sticking fault is detected, further pre-charging processes will be stopped to avoid potential fault expansion or damage. If the main contactor sticking fault is not active, jump to the pre-charging contactor closed state and continue the pre-charging process.

[0035] If the voltage at the front end of the main contactor is not greater than 380V, the main contactor and the pre-charge contactor are disconnected, and the main counter is cleared. This is a safety measure. When the voltage is insufficient, the contactor is disconnected to prevent potential electrical failure or damage. At the same time, the main counter is cleared to prepare for the start of the next pre-charge process.

[0036] Adhesion logic detection is a multi-step process designed to accurately determine whether the main contactor has a adhesion fault. It includes steps such as determining whether the main circuit is powered on, delaying the power-off of the auxiliary drive motor circuit, and determining the front-end voltage and the front-end and rear-end voltage difference of the main contactor. These steps together constitute a complete detection process to ensure that the adhesion fault of the main contactor can be accurately and reliably identified.

[0037] The pre-check state is the beginning of the entire pre-charging process and is also a key step to ensure safe operation. By performing voltage judgment and sticking logic detection in the pre-check state, potential faults can be discovered and handled in a timely manner, thereby avoiding more serious problems in the subsequent pre-charging process. In addition, the pre-check state can also provide necessary information and preparation for the subsequent pre-charging process to ensure the smooth progress of the entire process.

[0038] When the pre-charge contactor is closed, the pre-charge contactor is closed, while the main contactor is still open. The voltage at the front end of the main contactor is monitored to determine whether it is ready for the next main contactor closing operation. If the voltage is greater than 380V, the pre-charge counter is started, and the value of the pre-charge counter is used to determine whether to jump to the pre-charge timeout state or the main contactor closed state.

[0039] Specifically, Figure 2As shown, when the pre-charging state of the main circuit is the pre-charging contactor closed state, first detect whether the front-end voltage of the main contactor is greater than 380V. If it is greater than 380V, start the pre-charging counter and start timing. And judge the pre-charging counter time. If the pre-charging counter time is greater than 2.7 seconds, it means that the pre-charging process exceeds the predetermined time limit, and there may be some kind of fault or abnormality. At this time, it will jump to the pre-charging timeout state. If the pre-charging counter time is not greater than 2.7 seconds, further judge the relationship between the rear-end voltage and the front-end voltage of the main contactor. If it is not greater than 380V, disconnect the main contactor and the pre-charging contactor to ensure the safety of the circuit. Clear the pre-charging counter to prepare for the next pre-charging process.

[0040] When the pre-charge counter time is not greater than 2.7 seconds, further determine whether the voltage at the rear end of the main contactor is greater than 0.9 times the voltage at the front end of the main contactor. If it is greater than 0.9 times, it indicates that the main contactor has been closed normally and the circuit is in a normal state, and it will jump to the main contactor closed state. If it is not greater than 0.9 times, it means that the main contactor has not been closed normally or there is some kind of fault, and this round of identification process will end.

[0041] When the main contactor is in the closed state, the main contactor is closed, the delay counter is started, and the value of the delay counter is used to determine whether to jump to the pre-charging contactor disconnected and the main contactor closed state.

[0042] Specifically, Figure 3 As shown in the figure, when the main circuit pre-charge state reaches the main contactor closed state, it usually means that the main contactor has been successfully closed and the circuit has been established. However, in order to ensure the stability and safety of the circuit, further checks will be performed.

[0043] Once the main contactor is closed, a delay counter is started immediately. The purpose of this counter is to provide a short time window so that the stability of the circuit and the closing state of the main contactor can be monitored. During the operation of the delay counter, its accumulated time is constantly checked.

[0044] If the delay counter time is greater than 0.5 seconds, it means that the main contactor has remained closed for more than the predetermined time threshold (0.5 seconds), and the circuit is considered stable and can safely enter the next state. Therefore, it will jump to the state where the pre-charge contactor is disconnected and the main contactor is closed. In this state, the pre-charge contactor will be disconnected and the main contactor will remain closed to ensure the normal operation of the circuit. If the delay counter time is not greater than 0.5 seconds, it means that the state of the circuit or the main contactor is still unstable, or there is some kind of fault that prevents the main contactor from remaining closed for a long time. Therefore, this round of identification process will end.

[0045] When the pre-charge contactor is disconnected and the main contactor is closed, the pre-charge contactor has been disconnected, but the main contactor is still closed, clearing all related counters and the pre-charge failure fault.

[0046] Specifically, Figure 4 As shown in the figure, in this state, the pre-charge contactor is open and the main contactor is closed. This means that the circuit has completed the pre-charge process and the main circuit is ready for normal current transmission. Clear all counters to clear the pre-charge failure fault.

[0047] Clear all counters, including the main counter, precharge counter, and delay counter. The counters are used to record time or times during the previous precharge process to ensure the safety and reliability of the circuit. When the precharge process is successfully completed and the main circuit is ready for normal operation, these counters are no longer needed, so they are cleared to prepare for the next precharge process.

[0048] If a fault occurs during the previous pre-charging process (such as pre-charging timeout, voltage abnormality, etc.), a pre-charging failure fault will be recorded. When the main circuit enters the "pre-charging contactor disconnected and main contactor closed state", it means that the pre-charging process has been successfully completed, so this fault record can be cleared to ensure normal operation.

[0049] In the previous pre-charging process, the counter played an important role. The main counter is used to record the number or time of the pre-charging process to monitor the stability and reliability of the circuit; the pre-charging counter is used to record the time of the pre-charging process to ensure that the pre-charging process is completed within the specified time. If the pre-charging time exceeds the specified limit, it may indicate that there is a fault in the circuit; the delay counter is used to record a certain delay time after the main contactor is closed to ensure the stability and safety of the circuit. This delay time is used to wait for components such as capacitors or inductors in the circuit to fully discharge or charge to avoid instantaneous current shocks or voltage fluctuations.

[0050] If the pre-charge counter time exceeds the preset threshold (such as 2.7 seconds) when the pre-charge contactor is closed, it will jump to the pre-charge timeout state. In this state, the main contactor and pre-charge contactor will be disconnected, and all related counters will be cleared, and the pre-charge failure fault will be activated.

[0051] Specifically, Figure 5 As shown in the figure, when the main circuit pre-charging state enters the "pre-charging timeout state", it means that the pre-charging process has exceeded the predetermined time limit, which may be caused by some fault or abnormality. In this case, a series of measures need to be taken to ensure safety and prepare for troubleshooting.

[0052] First, the main contactor and pre-charge contactor need to be disconnected. This is to prevent further damage or safety hazards that may be caused by the circuit continuing to work in the pre-charge timeout state. Disconnecting these two contactors can ensure that the circuit is in a safe state and provide conditions for subsequent troubleshooting.

[0053] Next, all relevant counters need to be cleared. These counters may include main counters, precharge counters, and delay counters. The purpose of clearing these counters is to eliminate the data accumulated during the previous precharge process and provide a clean, non-interference starting point for the next precharge process.

[0054] Finally, the pre-charge failure fault needs to be activated. This is an important safety mechanism used to indicate that an abnormality has occurred during the pre-charge process. Activating the pre-charge failure fault can trigger the corresponding alarm or indication signal to alert the operator to pay attention and take appropriate troubleshooting measures.

[0055] Safety and reliability are critical when dealing with pre-charge timeout conditions. Disconnecting the contactor and clearing the counter prevents the circuit from continuing to operate in an abnormal state, thereby avoiding potential damage or danger. At the same time, activating the pre-charge failure fault ensures that the operator is informed of the fault condition in time and can take appropriate measures to repair it.

[0056] In actual applications, when the main circuit pre-charging state enters the pre-charging timeout state, the operator should respond quickly and take necessary troubleshooting measures. This includes checking the connection of the power supply, contactor and related circuits, and checking whether there are other potential sources of failure. After troubleshooting, the operator can restart the pre-charging process and ensure that it can work normally.

[0057] Furthermore, the main contactor sticking logic detection is a key step in the embodiment of the present application, which aims to identify whether the main contactor has a sticking fault through a series of logical judgments and counter operations. A sticking fault means that the contactor remains closed when it should be disconnected, which may cause circuit abnormality or equipment damage.

[0058] Specifically, Figure 6 As shown, first, it is necessary to check whether the main circuit pre-charging has been powered on. This is to ensure that the circuit is in the correct state before the adhesion detection. If it has been powered on, the next step is to clear the adhesion detection counter and restart the counting. This is to prepare for a new round of adhesion detection.

[0059] If the main circuit pre-charge is not powered on, the auxiliary drive motor circuit is powered off with a delay. This is to ensure that the circuit is in a safe state during the detection process. At the same time, the adhesion detection counter and cycle counter are cleared to clear the previous counting data for a new detection.

[0060] Next, determine whether the voltage at the front end of the main contactor is greater than 10V and whether the voltage difference between the front and rear ends is less than 3V. These two conditions together form the basis for adhesion detection. If the voltage at the front end of the main contactor is greater than 10V and the voltage difference between the front and rear ends is less than 3V, it indicates that adhesion may exist. At this time, the adhesion detection counter is incremented. If the voltage at the front end of the main contactor is not greater than 10V or the voltage difference between the front and rear ends is not less than 3V, it indicates that the current situation does not meet the adhesion conditions, so the adhesion detection counter is cleared.

[0061] After the above steps, it is also necessary to determine whether the value of the adhesion detection counter exceeds the preset threshold. This threshold is set based on actual conditions and experience to determine whether an adhesion fault has actually occurred. If the value of the adhesion detection counter is greater than the preset threshold, it is considered that an adhesion fault has occurred in the main contactor, and the corresponding fault indication or alarm is activated. If the value of the adhesion detection counter is not greater than the preset threshold, it is considered that no adhesion fault has occurred at present, and the relevant fault indication or alarm is prohibited.

[0062] Main contactor adhesion logic detection is an important part of the contactor fault identification method. Through precise logic judgment and counter operation, it can accurately identify whether the main contactor has adhesion fault, so that corresponding measures can be taken in time to ensure the safety and stable operation of the circuit. This method not only improves the accuracy and efficiency of fault identification, but also reduces equipment damage and maintenance costs caused by faults.

[0063] Furthermore, the embodiment of the present application also includes a special case processing logic when the main circuit pre-charging state is a pre-check state.

[0064] The pre-check state is an initial state in the main circuit pre-charging process, which is used to check the readiness of the circuit and contactor. In this state, the pre-check state is judged every 10 milliseconds, and a total of 20 times, which means that the entire pre-check process will last 200 milliseconds.

[0065] In the pre-check state, both the pre-charge contactor and the main contactor are in the disconnected state to ensure the safety and readiness of the circuit. By monitoring the voltage difference between the front and rear ends of the main contactor, if the voltage difference is less than 30V, it is judged that the main contactor has a sticking fault. Once the main contactor sticking fault is detected, the judgment of the next pre-charge contactor closing state will no longer be executed, but other fault handling measures such as alarm, shutdown, etc. will be taken.

[0066] In summary, the embodiment of the present application provides a method for identifying contactor faults based on the front and rear voltage method of the contactor, and elaborates on the various stages of the main circuit pre-charging state and its processing logic. The pre-charging state includes pre-check, pre-charging contactor closure, main contactor closure, pre-charging contactor disconnection and main contactor closure, and pre-charging timeout. In the pre-check stage, by judging whether the front voltage of the main contactor is greater than 380V, it is determined whether to perform adhesion logic detection. If the voltage is insufficient, the contactor is disconnected and the counter is cleared. The adhesion logic detection includes multiple steps to accurately identify the adhesion fault of the main contactor. In the closed state of the pre-charging contactor, by monitoring the voltage and time, it is determined whether to jump to other states or perform fault processing. After the main contactor is closed, the delay counter is started to ensure that the circuit is stable. If the pre-charging timeout, the contactor is disconnected, the counter is cleared, and the fault indication is activated. In addition, specific steps for the main contactor adhesion logic detection and special case processing logic are provided, that is, the processing measures when the main contactor adhesion fault is detected in the pre-check state. This method improves the accuracy and efficiency of fault identification and reduces equipment damage and maintenance costs.

[0067] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0068] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for identifying contactor faults based on the front and rear voltage method of the contactor, characterized in that: The method comprises: Obtaining the main circuit pre-charging state, wherein the main circuit pre-charging state includes a pre-check state, a pre-charging contactor closing state, a main contactor closing state, a pre-charging contactor disconnected and main contactor closed state, and a pre-charging timeout state; When the pre-charge state of the main circuit is the pre-check state, determine whether the front-end voltage of the main contactor is greater than 380V. If the front-end voltage of the main contactor is greater than 380V, perform the main contactor adhesion logic detection to determine whether the main contactor adhesion fault is activated. If the main contactor adhesion fault is activated, maintain the current state; if the main contactor adhesion fault is not activated, jump to the pre-charge contactor closed state; if the front-end voltage of the main contactor is not greater than 380V, disconnect the main contactor and the pre-charge contactor, and clear the main counter; When the pre-charging state of the main circuit is the pre-charging contactor closed state, determine whether the front-end voltage of the main contactor is greater than 380V. If the front-end voltage of the main contactor is greater than 380V, start the pre-charging counter to determine whether the pre-charging counter time is greater than 2.7 seconds. If the pre-charging counter time is greater than 2.7 seconds, jump to the pre-charging timeout state; if the pre-charging counter time is not greater than 2.7 seconds, determine whether the rear-end voltage of the main contactor is greater than 0.9 times the front-end voltage of the main contactor. If the rear-end voltage of the main contactor is greater than 0.9 times the front-end voltage of the main contactor, jump to the main contactor closed state; if the rear-end voltage of the main contactor is not greater than 0.9 times the front-end voltage of the main contactor, end this round of identification; if the front-end voltage of the main contactor is not greater than 380V, disconnect the main contactor and the pre-charging contactor, and clear the pre-charging counter; When the main circuit pre-charge state is the main contactor closed state, the delay counter is started to determine whether the delay counter time is greater than 0.5 seconds; if the delay counter time is greater than 0.5 seconds, it jumps to the pre-charge contactor disconnected and the main contactor closed state; if the delay counter time is not greater than 0.5 seconds, this round of identification ends; When the pre-charging state of the main circuit is that the pre-charging contactor is disconnected and the main contactor is closed, all counters are cleared to clear the pre-charging failure fault. All counters include the main counter, pre-charging counter and delay counter; When the pre-charging state of the main circuit is the pre-charging timeout state, the main contactor and the pre-charging contactor are disconnected, all counters are cleared, and the pre-charging failure fault is activated.

2. The method according to claim 1, characterized in that The main contactor sticking logic detection includes: Determine whether the main circuit pre-charging is enabled by power on. If it is enabled by power on, clear the adhesion detection counter and restart the counting; If it is not powered on, the auxiliary drive motor circuit is powered off with a delay, the adhesion detection counter and the cycle counter are cleared, and it is determined whether the front-end voltage of the main contactor is greater than 10V and the front-end and rear-end pressure difference is less than 3V. If the front-end voltage of the main contactor is greater than 10V and the front-end and rear-end pressure difference is less than 3V, the adhesion detection counter is incremented and it is determined whether the adhesion detection counter is greater than a preset threshold; if the front-end voltage of the main contactor is not greater than 10V and the front-end and rear-end pressure difference is not less than 3V, the adhesion detection counter is cleared; If the adhesion detection counter is greater than a preset threshold, the main contactor adhesion fault is activated; if the adhesion detection counter is not greater than the preset threshold, the main contactor adhesion fault is prohibited.

3. The method according to claim 1 or 2, characterized in that The method comprises: When the main circuit pre-charge state is the pre-check state, the pre-check state is judged once every 10ms, and judged 20 times. In the pre-check state, the pre-charge contactor and the main contactor are both disconnected. If the voltage difference between the front and rear ends of the main contactor is less than 30V, it is judged that the main contactor has a adhesion fault, and the judgment of the next pre-charge contactor closing state will no longer be executed.

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