A method for identifying contactor faults based on the front and rear end voltage method of the contactor

Abstract

The present application discloses a method for identifying contactor faults based on the front-end and back-end voltages of the contactor, which relates to the technical field of contactor fault identification. The pre-charge state of the main circuit is divided into pre-inspection, pre-charge contactor closed, main contactor closed, pre-charge contactor disconnected and main contactor closed, and pre-charge timeout state; in the pre-inspection state, if the voltage at the front end of the main contactor is greater than 380V, adhesion logic detection is performed; if it is not greater than, the contactor is disconnected and the main counter is cleared; when the pre-charge contactor is closed, the circuit state is judged according to the voltage and time; after the main contactor is closed, a delay counter is started to ensure the stability of the circuit; after the pre-charge is completed, the counter and fault records are cleared; if the pre-charge times out, the contactor is disconnected, the counter is cleared and the fault is activated; in addition, the pre-inspection state also includes special situation handling logic to ensure the safety of the circuit. The present application detects the fault state of the contactor by monitoring the voltage change of the main circuit in different pre-charge states, improving the driving safety.

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-end and rear-end voltage method. Background Art

[0002] Currently, 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, when the whole vehicle is powered off, 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, using the feedback status of the auxiliary contact to identify the main contactor fault is a relatively good method. However, in the actual field application of the all-in-one product, it was found that the auxiliary contact mechanical structure of the main contactor of the main circuit was damaged due to excessive temperature, affecting 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-charge states.

[0005] To achieve the above objectives, the present invention 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-charge status, which includes pre-check status, pre-charge contactor closed status, main contactor closed status, pre-charge contactor disconnected and main contactor closed status, and pre-charge timeout status;

[0007] When the main circuit pre-charge state 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 main circuit pre-charging state is the state where the pre-charging contactor is closed, determine whether the voltage at the front end of the main contactor is greater than 380V. If the voltage at the front end of the main contactor is greater than 380V, start the pre-charging counter, and determine whether the time of the pre-charging counter is greater than 2.7 seconds. If the time of the pre-charging counter is greater than 2.7 seconds, jump to the pre-charging timeout state; if the time of the pre-charging counter is not greater than 2.7 seconds, determine whether the voltage at the back end of the main contactor is greater than 0.9 times the voltage at the front end of the main contactor. If the voltage at the back end of the main contactor is greater than 0.9 times the voltage at the front end of the main contactor, jump to the main contactor closed state; if the voltage at the back end of the main contactor is not greater than 0.9 times the voltage at the front end of the main contactor, end this round of identification; if the voltage at the front end 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-charging state is the state where the main contactor is closed, start the delay counter, and determine whether the time of the delay counter is greater than 0.5 seconds; if the time of the delay counter is greater than 0.5 seconds, jump to the state where the pre-charging contactor is disconnected and the main contactor is closed; if the time of the delay counter is not greater than 0.5 seconds, end this round of identification.

[0010] When the main circuit pre-charging state is the state where the pre-charging contactor is disconnected and the main contactor is closed, clear all counters, clear the pre-charging failure fault, and all counters include the main counter, the pre-charging counter, and the delay counter.

[0011] When the main circuit pre-charging state is the pre-charging timeout state, disconnect the main contactor and the pre-charging contactor, clear all counters, and activate the pre-charging failure fault.

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

[0013] Further, the main contactor adhesion logic detection includes:

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

[0015] If it is not powered on and enabled, perform delayed power-off of the auxiliary drive motor circuit, clear the adhesion detection counter and the cycle counter, and determine whether the voltage at the front end of the main contactor is greater than 10V and whether the pressure difference between the front and back ends is less than 3V. If the voltage at the front end of the main contactor is greater than 10V and the pressure difference between the front and back ends is less than 3V, increment the adhesion detection counter and determine 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 pressure difference between the front and back ends is not less than 3V, clear the adhesion detection counter.

[0016] If the adhesion detection counter is greater than the preset threshold, activate the main contactor adhesion fault; if the adhesion detection counter is not greater than the preset threshold, prohibit the main contactor adhesion fault.

[0017] Further, when the main circuit pre-charge state is the pre-inspection state, judge the pre-inspection state once every 10 ms for 20 times. In the pre-inspection state, both the pre-charge contactor and the main contactor are disconnected. If the voltage difference across the main contactor is less than 30 V, it is determined that the main contactor has an adhesion fault, and the judgment of the next pre-charge contactor closed state is no longer executed.

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

[0019] The embodiments of the present application can accurately judge the state of the main contactor by adopting the fault identification method based on the voltage across the front and rear ends of the contactor, and can effectively distinguish 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 change across the front and rear ends of the contactor, the state change of the contactor during the discharge process can be accurately identified, thus avoiding misjudgment caused by rapid discharge.

[0020] The embodiments of the present application do not rely on the state of the auxiliary contacts, but directly judge the fault by monitoring the voltage across the front and rear ends of the contactor, thus avoiding misjudgment or missed judgment caused by damage to the auxiliary contacts; the embodiments of the present application improve the driving safety by monitoring the state of the main contactor in real time and timely discovering and handling potential faults.

[0021] The embodiments of the present application can timely discover and handle faults by accurately monitoring and judging the state of the contactor, avoiding shutdown or damage caused by failure to timely discover faults. At the same time, since it does not rely on the state of the auxiliary contacts, the unstable factors caused by damage to the auxiliary contacts are reduced, and the reliability and stability are enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shows the pre-inspection state flow schematic diagram of the method for identifying contactor faults based on the voltage across the front and rear ends of the contactor according to the embodiments of the present application;

[0023] Figure 2 Shows the pre-charge contactor closed state flow schematic diagram of the method for identifying contactor faults based on the voltage across the front and rear ends of the contactor according to the embodiments of the present application;

[0024] Figure 3 Shows the main contactor closed state flow schematic diagram of the method for identifying contactor faults based on the voltage across the front and rear ends of the contactor according to the embodiments of the present application;

[0025] Figure 4 Shows the schematic diagram of the pre-charge contactor disconnection and main contactor closed state process of the method for identifying contactor faults based on the voltage method at the front and rear ends of the contactor in the embodiment of the present application;

[0026] Figure 5 Shows the schematic diagram of the pre-charge timeout state process of the method for identifying contactor faults based on the voltage method at the front and rear ends of the contactor in the embodiment of the present application;

[0027] Figure 6 Shows the schematic diagram of the main contactor adhesion logic detection process of the method for identifying contactor faults based on the voltage method at the front and rear ends of the contactor in the embodiment of the present application. Detailed implementation manners

[0028] To make the above objects, features and advantages of the present application more obvious and understandable, the following will describe the detailed implementation manners of the present application in conjunction with the accompanying drawings. It can be understood that the specific embodiments described herein are only used to explain the present application, rather than limiting the present application. Additionally, it should be noted that for the convenience of description, only parts related to the present application rather than all structures are shown in the accompanying drawings. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

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

[0030] Referring to "embodiment" in the present application means that a specific feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in the present application can be combined with other embodiments.

[0031] The embodiment of the present application provides a method for identifying contactor faults based on the voltage method at the front and rear ends of the contactor, where the pre-charge state of the main circuit includes a pre-inspection state, a pre-charge contactor closed state, a main contactor closed state, a pre-charge contactor disconnection and main contactor closed state, and a pre-charge timeout state pre-inspection state.

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

[0033] If the voltage at the front end of the main contactor is greater than 380V, then perform the adhesion logic detection of the main contactor. The adhesion logic detection is a complex judgment process, including steps such as determining whether the main circuit is powered on and enabled, performing a delayed power-off of the auxiliary drive motor circuit, and judging the voltage and voltage difference. Finally, determine whether there is an adhesion fault in the main contactor.

[0034] If the main contactor adhesion fault is activated, maintain the current state and do not perform subsequent operations. This means that if an adhesion fault is detected, the further pre-charge process will be stopped to avoid potential fault expansion or damage. If the main contactor adhesion fault is not activated, jump to the pre-charge contactor closed state and continue to execute the pre-charge process.

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

[0036] The adhesion logic detection is a multi-step process aimed at accurately judging whether there is an adhesion fault in the main contactor. It includes steps such as determining whether the main circuit is powered on and enabled, performing a delayed power-off of the auxiliary drive motor circuit, and judging the voltage at the front end of the main contactor and the voltage difference between the front and rear ends. 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-inspection state is the starting stage of the entire pre-charge process and a key step to ensure safe operation. By performing voltage judgment and adhesion logic detection in the pre-inspection state, potential faults can be detected and processed in a timely manner, thus avoiding more serious problems in the subsequent pre-charge process. In addition, the pre-inspection state can also provide necessary information and preparations for the subsequent pre-charge process to ensure the smooth progress of the entire process.

[0038] In the pre-charge contactor closed state, the pre-charge contactor is closed while the main contactor remains open. By monitoring the voltage at the front end of the main contactor, determine whether it is ready to perform the next main contactor closing operation. If the voltage is greater than 380V, start the pre-charge counter, and based on the value of the pre-charge counter, decide whether to jump to the pre-charge timeout state or the main contactor closed state.

[0039] Specifically, such as Figure 2As shown, when the main circuit pre-charging state is the state where the pre-charging contactor is closed, first detect whether the voltage at the front end of the main contactor is greater than 380V. If it is greater than 380V, start the pre-charging counter and start timing. Then judge the time of the pre-charging counter. If the time of the pre-charging counter is greater than 2.7 seconds, it means that the pre-charging process has exceeded the predetermined time limit, and there may be some kind of fault or abnormality. At this time, jump to the pre-charging timeout state. If the time of the pre-charging counter is not greater than 2.7 seconds, then further judge the relationship between the voltage at the back end of the main contactor and the voltage at the front end. 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 time of the pre-charging counter is not greater than 2.7 seconds, further judge whether the voltage at the back 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, this indicates that the main contactor has closed normally and the circuit is in a normal state. At this time, jump to the state where the main contactor is closed. If it is not greater than 0.9 times, it means that the main contactor fails to close normally or there is some kind of fault. At this time, end this round of identification process.

[0041] When the main contactor is in the closed state, the main contactor closes, starts the delay counter, and decides whether to jump to the state where the pre-charging contactor is disconnected and the main contactor is closed according to the value of the delay counter.

[0042] Specifically, as Figure 3 shown, when the main circuit pre-charging state reaches the state where the main contactor is closed, this usually means that the main contactor has closed successfully and the circuit has been established. But to ensure the stability and safety of the circuit, further checks will be performed.

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

[0044] If the time of the delay counter is greater than 0.5 seconds, this indicates that the main contactor has remained closed for more than the predetermined time threshold (0.5 seconds), then it is considered that the circuit has been stable and can safely enter the next state. Therefore, at this time, jump to the state where the pre-charging contactor is disconnected and the main contactor is closed. In this state, the pre-charging contactor will be disconnected and the main contactor will remain closed to ensure the normal operation of the circuit. If the time of the delay counter 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 causing the main contactor to not remain closed for a long time. Therefore, end this round of identification process.

[0045] When the precharge contactor is open and the main contactor is closed, the precharge contactor has already opened while the main contactor remains closed. Clear all relevant counters and clear the precharge failure fault.

[0046] Specifically, as Figure 4 shown, in this state, the precharge contactor has already opened while the main contactor is in the closed state. This means that the circuit has completed the precharge process and the main circuit is ready for normal current transmission. Clear all counters and clear the precharge failure fault.

[0047] Clear all counters, which includes the main counter, precharge counter, and delay counter. The counters were used during the previous precharge process to record time or number of times 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 occurred during the previous precharge process (such as precharge timeout, abnormal voltage, etc.), a precharge failure fault will be recorded. When the main circuit enters the "precharge contactor open and main contactor closed state", it indicates that the precharge process has been successfully completed, so this fault record can be cleared to ensure normal operation.

[0049] During the previous precharge process, the counters played an important role. Among them, the main counter is used to record the number of times or time of the precharge process to monitor the stability and reliability of the circuit; the precharge counter is used to record the time of the precharge process to ensure that the precharge process is completed within the specified time. If the precharge time exceeds the specified limit, it may indicate a circuit fault; the delay counter, after the main contactor is closed, is used to record a certain delay time 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 surges or voltage fluctuations.

[0050] If, when the precharge contactor is closed, the time of the precharge counter exceeds the preset threshold (such as 2.7 seconds), it jumps to the precharge timeout state. In this state, the main contactor and the precharge contactor will be opened, all relevant counters will be cleared, and at the same time, the precharge failure fault will be activated.

[0051] Specifically, as Figure 5 shown, when the main circuit precharge state enters the "precharge timeout state", this means that the precharge process has exceeded the predetermined time limit, possibly due to some fault or abnormality. In this case, a series of measures need to be taken to ensure safety and prepare for troubleshooting.

[0052] First, disconnect the main contactor and pre-charge contactor. This prevents further damage or safety hazards that could occur if the circuit continues to operate during a pre-charge timeout. Disconnecting these two contactors ensures a safe circuit state, facilitating subsequent troubleshooting.

[0053] Next, all relevant counters need to be cleared. These counters may include the main counter, precharge counter, and delay counter. 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 precharge failure fault needs to be activated. This is an important safety mechanism that indicates an abnormality during the precharge process. Activating the precharge failure fault triggers an appropriate alarm or indicator signal, alerting the operator to take appropriate troubleshooting measures.

[0055] Safety and reliability are paramount when handling precharge timeout conditions. Disconnecting the contactor and clearing the counter prevents the circuit from continuing to operate under abnormal conditions, thereby avoiding potential damage or danger. Furthermore, activating a precharge failure fault ensures that operators are promptly notified of the fault and can take appropriate action to remedy the situation.

[0056] In practice, when the main circuit precharge state enters the precharge timeout state, the operator should respond quickly and take necessary troubleshooting measures. This includes checking the power supply, contactor, and related circuit connections, as well as checking for other potential sources of failure. After troubleshooting, the operator can restart the precharge process and ensure normal operation.

[0057] Furthermore, main contactor sticking logic detection is a key step in the embodiments of this application. It aims to identify whether a main contactor has a sticking fault through a series of logical judgments and counter operations. A sticking fault occurs when the contactor remains closed when it should be open, which may cause circuit abnormalities or equipment damage.

[0058] Specifically, such as Figure 6 As shown, first, check whether the main circuit precharge is enabled. This ensures that the circuit is in the correct state before performing sticking detection. If it is, proceed to the next step, which is to clear the sticking detection counter and restart the count. This prepares for a new round of sticking detection.

[0059] If the main circuit precharge is not enabled, the auxiliary drive motor circuit is powered off with a delay. This ensures the circuit remains safe during the test. Simultaneously, the adhesion detection counter and cycle counter are reset to zero. This clears previous count data for a new test.

[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, increment the adhesion detection counter. 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 a preset threshold. This threshold is set according to the actual situation and experience and is used to judge whether an adhesion failure has actually occurred. If the value of the adhesion detection counter is greater than the preset threshold, it is considered that the main contactor has an adhesion failure, 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 failure has occurred currently, and the relevant fault indication or alarm is prohibited.

[0062] The adhesion logic detection of the main contactor is an important part of the contactor fault identification method. Through precise logical judgment and counter operation, it can accurately identify whether the main contactor has an adhesion failure, so as to take corresponding measures in a timely manner to ensure the safe 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 situation handling logic when the pre-charging state of the main circuit is the pre-inspection state.

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

[0065] In the pre-inspection state, both the pre-charging contactor and the main contactor are in the open 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 an adhesion failure. Once the adhesion failure of the main contactor is detected, the judgment of the next pre-charging contactor closed state will no longer be executed, but other fault handling measures will be taken, such as alarming, stopping, etc.

[0066] In summary, the embodiment of the present application provides a method for identifying contactor faults based on the front and rear end voltages of the contactor, and elaborates in detail each stage of the main circuit pre-charge state and its processing logic. The pre-charge state includes states such as pre-inspection, pre-charge contactor closed, main contactor closed, pre-charge contactor disconnected and main contactor closed, and pre-charge timeout. In the pre-inspection stage, by judging whether the voltage at the front end of the main contactor is greater than 380V, it is decided whether to perform the 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 state where the pre-charge contactor is closed, by monitoring the voltage and time, it is judged whether to jump to other states or perform fault handling. After the main contactor is closed, a delay counter is started to ensure the stability of the circuit. If the pre-charge times out, the contactor is disconnected, the counter is cleared, and the fault indication is activated. In addition, the specific steps of the main contactor adhesion logic detection and the processing logic for special cases are provided, that is, the handling measures when the main contactor adhesion fault is detected in the pre-inspection 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 "include", "comprise" 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 not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including such element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments 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 a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may 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 have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection scope of the present application.

Claims

1. A method for identifying contactor faults based on the front and rear end voltage method of the contactor, characterized in that The method includes: Obtaining the pre-charging state of the main circuit, where the pre-charging state of the main circuit includes a pre-inspection state, a pre-charging contactor closed state, a main contactor closed state, a pre-charging contactor open and main contactor closed state, and a pre-charging timeout state; When the pre-charging state of the main circuit is the pre-inspection state, determine whether the voltage at the front end of the main contactor is greater than 380V. If the voltage at the front end 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-charging contactor closed state; if the voltage at the front end of the main contactor is not greater than 380V, disconnect the main contactor and the pre-charging 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 voltage at the front end of the main contactor is greater than 380V. If the voltage at the front end of the main contactor is greater than 380V, start the pre-charging counter and determine whether the time of the pre-charging counter is greater than 2.7 seconds. If the time of the pre-charging counter is greater than 2.7 seconds, jump to the pre-charging timeout state; if the time of the pre-charging counter is not greater than 2.7 seconds, 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 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, jump to the main contactor closed state; if the voltage at the rear end of the main contactor is not greater than 0.9 times the voltage at the front end of the main contactor, end this round of identification; if the voltage at the front end 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 pre-charging state of the main circuit is the main contactor closed state, start the delay counter and determine whether the time of the delay counter is greater than 0.5 seconds; if the time of the delay counter is greater than 0.5 seconds, jump to the pre-charging contactor open and main contactor closed state; if the time of the delay counter is not greater than 0.5 seconds, end this round of identification; When the pre-charging state of the main circuit is the pre-charging contactor open and main contactor closed state, clear all counters, clear the pre-charging failure fault, and all counters include the main counter, the pre-charging counter, and the delay counter; When the pre-charging state of the main circuit is the pre-charging timeout state, disconnect the main contactor and the pre-charging contactor, clear all counters, and activate the pre-charging failure fault.

2. The method according to claim 1, characterized in that, The main contactor adhesion logic detection includes: Determine whether the main circuit pre-charging is powered on and enabled. If it is powered on and enabled, clear the adhesion detection counter and re-count; If it is not powered on and enabled, perform the auxiliary drive motor circuit delayed power-off, clear the adhesion detection counter and the cycle counter, and determine whether the voltage at the front end of the main contactor is greater than 10V and the front-back voltage difference is less than 3V. If the voltage at the front end of the main contactor is greater than 10V and the front-back voltage difference is less than 3V, increment the adhesion detection counter and determine 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 front-back voltage difference is not less than 3V, clear the adhesion detection counter; If the contact adhesion detection counter is greater than a preset threshold value, activate the main contactor adhesion fault; if the contact adhesion detection counter is not greater than the preset threshold value, prohibit the main contactor adhesion fault.

3. The method according to claim 1 or 2, characterized in that, The method includes: When the main circuit pre-charging state is the pre-inspection state, judge the pre-inspection state once every 10 ms for 20 times. In the pre-inspection state, both the pre-charging contactor and the main contactor are disconnected. If the pressure difference between the front and rear ends of the main contactor is less than 30 V, it is judged that there is a main contactor adhesion fault, and the judgment of the next pre-charging contactor closing state is not executed.

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