Method for comprehensively diagnosing clamping, separating and clamping faults of contactor for traction converter

Abstract

The invention discloses a comprehensive diagnosis method for clamping, separating and clamping faults of a contactor for a traction converter, is used for solving the technical problem that faults are likely to be misreported in the prior art, and belongs to the technical field of converter fault diagnosis. The detection loop adopts a normally-open auxiliary switch parallel connection mode to feed back the state of the contactor, so that the false alarm rate of the contactor clamping failure can be reduced; the detection loop adopts a normally-open auxiliary switch series connection mode to feed back the contactor state, so that the clamping fault false alarm rate of the contactor can be reduced; the control unit adds a reset condition control strategy to reduce the fault false alarm rate; the control strategy that the control unit detects the state of the auxiliary switch of the contactor and detects whether the voltage and current values in the loop meet the threshold value can reduce the fault false alarm rate. The accuracy of fault diagnosis of the contactor for the traction converter is improved, the fault level is reduced to the maximum extent, meanwhile, the comprehensive diagnosis method is simple in judgment logic, the occupancy rate of computing resources of a control unit is low, and the overall performance of a traction system and the operation efficiency of a locomotive are improved.

Description

Technical Field

[0001] This invention belongs to the field of converter fault diagnosis technology, and specifically relates to a comprehensive diagnostic method for contactor card opening and closing faults in traction converters. Background Technology

[0002] In recent years, the requirements for the safety and reliability of locomotive operation in the rail transit sector have been continuously increasing. As the core component of the traction electric transmission system of electric locomotives, reducing the failure level and failure rate of locomotive converters has received increasing attention. The contactor in the main circuit of the converter accounts for a large proportion of the failure rate, resulting in significant impact and high maintenance costs.

[0003] The traction converter obtains electrical energy from the overhead contact line, converts the single-phase AC power from the secondary side of the transformer into the DC power required by the system through contactors and rectifiers on the input side circuit, and then supplies power to the traction motor through the traction inverter, thereby driving the traction motor. The contactors in the main circuit are used to control the connection and disconnection of the pre-charging circuit and the main circuit, and also undertake the function of fault isolation in the converter system. The reliability of the contactor main contacts and auxiliary interlocking devices directly affects the power output, operational continuity, and power supply safety of the traction electric drive system.

[0004] The electrical connection of a contactor consists of three parts: the actuating mechanism, the driving mechanism, and the auxiliary mechanism. The actuating mechanism refers to the main contacts, which are responsible for connecting and disconnecting the main circuit and carrying normal operating current. The driving mechanism refers to the electromagnetic system, composed of an electromagnetic coil, an iron core, and an armature. The electromagnetic coil is connected to a low-voltage control circuit, and the control unit controls the energization of the electromagnetic coil. The electromagnetic energy generated by the electromagnetic coil is converted into mechanical energy to actuate the contacts. The auxiliary mechanism refers to microswitches, consisting of multiple normally open and normally closed auxiliary switches interlocked with the main contacts. The auxiliary switches are connected to a low-voltage detection circuit. The actuation of the main contacts drives the auxiliary switches. The control unit receives feedback on the on / off status of the auxiliary switches to determine the contactor's open / closed state. If the actuating mechanism, driving mechanism, and auxiliary mechanism operate in the same manner and with the same number of cycles within a specified time, it is considered normal and effective; otherwise, it is considered abnormal.

[0005] In northern regions, locomotives operate in windy, dusty, and hot environments. Factors such as low dust protection levels for the locomotives, converter cabinets, and contactors, along with malfunctions in drive and actuation mechanisms and auxiliary microswitches, increase the probability of contactor jamming or disengagement faults. These faults inevitably lead to a loss of traction / braking power. According to fault severity, from highest to lowest: Main contactor 6 jammed > Pre-charging contactor 4 disengaged / Main contactor 6 disengaged > Pre-charging contactor 4 jammed. The higher the fault severity, the greater the power loss and the lower the operational safety. For example, a main contactor 6 jammed is a major fault, requiring the tripping of the main circuit breaker 2 to prevent further damage. After the main circuit breaker 2 trips, the locomotive will lose half or all of its power and will be unable to continue operating.

[0006] The pantograph 1 collects current from the overhead contact line and supplies AC power to the main transformer 3 on the locomotive, serving as the power source for the entire locomotive.

[0007] Main circuit breaker 2 is used to control the connection and disconnection of the circuit between the locomotive's internal equipment and the high-voltage power grid.

[0008] The secondary traction winding of the main transformer 3 is connected to the input terminal of the converter, and the secondary side of the transformer outputs single-phase AC power to the input terminal of the converter.

[0009] The AC input circuit of the converter is mainly composed of a branch connected in parallel, consisting of one main contactor 6, one pre-charge contactor 4, and one pre-charge resistor 5. The intermediate DC circuit of the converter consists of a four-quadrant module 7, an intermediate support capacitor 8, a slow-release resistor 9, etc.

[0010] The pre-charge contactor 4 is used to control the connection / disconnection of the input terminal of the pre-charge circuit of the four-quadrant converter with the secondary traction winding of the main transformer 3.

[0011] The pre-charge resistor 5 is used to limit the amplitude of the charging current during the initial stage of the four-quadrant converter to prevent damage to the device from instantaneous surge current.

[0012] The main contactor 6 is used to control the connection / disconnection of the input terminal of the main circuit of the four-quadrant converter and the secondary traction winding of the main transformer 3, providing power for the normal operation of the four-quadrant rectifier.

[0013] The main function of the intermediate support capacitor 8 is to stabilize the voltage and absorb the ripple voltage of the intermediate circuit, so as to achieve instantaneous power balance between the four-quadrant converter and the motor inverter.

[0014] The main function of the four-quadrant module 7 is to pulse rectify the input single-phase AC power to charge the intermediate DC circuit intermediate support capacitor 8 to form an intermediate DC voltage for use by the chopper circuit, inverter circuit and auxiliary inverter circuit.

[0015] The normal operating principle of the traction converter is as follows: After the locomotive main circuit breaker 2 is closed, the secondary side of the transformer is energized. The traction converter pre-charging contactor 4 closes first, and the voltage at the intermediate DC circuit capacitor terminal is charged to more than 85% of the peak voltage of the transformer secondary side through the pre-charging resistor 5. Then the main contactor 6 closes. To avoid the arcing effect caused by the breaking current when the pre-charging contactor 4 is opened, the opening of the pre-charging contactor 4 is appropriately delayed. The four-quadrant start-up is then carried out and the intermediate voltage is raised to the rated operating voltage. The four-quadrant start-up process ends.

[0016] In existing technology, the auxiliary mechanism of a typical traction converter contactor is connected to the detection circuit via a set of normally open switches. In actual locomotive operation, after a contactor is reported as stuck, some faults may disappear after a fault reset, and the contactor may test normally with repeated switching operations. These types of faults are usually considered false alarms. This problem significantly impacts locomotive operating safety and increases maintenance costs.

[0017] Introduction to existing technical solutions: 1) The detection circuit of the contactor used in locomotive and EMU converter products detects the status of a single normally open auxiliary switch to determine the opening and closing status of the contactor's main contacts.

[0018] 2) The control unit determines the contactor jamming / unlocking fault protection strategy as follows: If the control unit does not receive feedback on the opening / closing of the pre-charging contactor 4 and the main contactor 6 after issuing the open / close command, the traction protection is triggered, the pre-charging contactor 4 and the main contactor 6 are opened, and the four quadrants and the inverter stop working. The traction protection after the main contactor 6 jamming fault also needs to disconnect the main circuit breaker 2.

[0019] The existing technology has the following drawbacks: 1) The contactor uses a separate normally open auxiliary switch connected to the detection circuit. When the auxiliary switch becomes unstable due to dust contamination, interference or other factors, it may falsely report a contactor jamming or disassembly fault.

[0020] 2) The protection actions for the pre-charging contactor 4's open / closed fault and the main contactor 6's open fault both require isolating the corresponding faulty shaft converter. The protection action for the main contactor 6's close fault requires disconnecting the main circuit breaker 2, isolating all converters in that section or frame, causing the locomotive to be unable to continue operating and affecting the safety of train operation on the line. Summary of the Invention

[0021] The purpose of this invention is to provide a comprehensive diagnostic method for contactor card opening and closing faults in traction converters, which solves the technical problem of false alarms that are prone to occur in the prior art.

[0022] This invention is achieved using the following technical solution: A comprehensive diagnostic method for contactor card opening and closing faults in a traction converter. The traction converter obtains electrical energy from the overhead contact line and converts the single-phase AC power on the secondary side of the transformer into the DC power required by the system through the input side circuit contactor and rectifier. In the main circuit, the contactor is used to control the connection and disconnection of the pre-charging circuit and the main circuit, and also undertakes the function of fault disconnection and isolation of the converter system. The electrical connection of a contactor consists of three parts: the actuating mechanism, the driving mechanism, and the auxiliary mechanism; among which the actuating mechanism is responsible for connecting and disconnecting the circuit and carrying the normal operating current. The control unit in the drive mechanism controls the on and off of the coil, and the electromagnetic energy generated by the coil is converted into mechanical energy that drives the action mechanism. The auxiliary mechanism refers to the micro switch, which consists of multiple normally open and normally closed auxiliary switches interlocked with the actuating mechanism. The auxiliary switch is connected to the low-voltage detection circuit. The actuating mechanism drives the auxiliary switch to operate. The control unit receives feedback on the on / off status of the auxiliary switch to determine the open / closed status of the contactor. The detection circuit adopts a normally open auxiliary switch feedback method, and the contactor is judged by receiving the on / off status feedback of the auxiliary switch through the control unit.

[0023] In application, increasing the redundancy of contactor closing and / or opening feedback can reduce the probability of false alarms of contactor jamming and / or jamming faults due to unstable feedback from a single auxiliary switch.

[0024] More preferably, the auxiliary switch feedback method is a parallel method, which increases the redundancy of contactor closure feedback and can reduce the false alarm rate of contactor jamming failure due to unstable feedback from a single auxiliary switch. After the control unit sends a control command to the contactor to close, the drive mechanism coil is energized, causing the main contacts of the actuating mechanism to close. The two normally open circuits of the auxiliary mechanism change from open to closed. When the control unit receives a high-level feedback signal from any auxiliary switch, it determines that the contactor is normally closed.

[0025] Preferably, the auxiliary switch feedback is in series, increasing the redundancy of the contactor disconnection feedback and reducing the probability of false alarms due to unstable feedback from a single auxiliary switch. This ensures that after the control unit sends a disconnect command to the contactor, the drive mechanism coil loses power, causing the main contacts of the actuating mechanism to disconnect. The two normally open circuits of the auxiliary mechanism change from closed to open. If any one of the auxiliary switch circuits is open, the control unit receives a low-level feedback from the auxiliary switch, thus determining that the contactor has disconnected normally.

[0026] In a further preferred embodiment, after the control unit detects a contactor jamming fault, it increases the number of self-reset checks in the traction system. If the fault cannot be eliminated, it is determined to be a genuine contactor jamming fault. The contactor jamming fault is detected by the traction control unit. Increasing the number of self-reset checks means that after the traction control unit detects a fault once, it automatically eliminates the fault term and then checks again. Generally, the number of resets is 1-3.

[0027] In a further preferred embodiment, if the control unit detects a pre-charge contactor engagement fault that cannot be eliminated, it determines that the pre-charge contactor engagement fault is genuine. In this case, the traction converter maintains the contactor state and continues to operate without causing power loss.

[0028] In a further preferred embodiment, if the control unit detects a main contactor engagement fault and receives feedback from the main contactor closing even though the main circuit breaker is not closed, the control unit will determine that the contactor auxiliary mechanism has falsely reported an engagement fault. In this case, the converter on that shaft will be isolated, resulting in the loss of traction / braking force on that shaft. The logic for detecting engagement of the pre-charge contactor is that the traction control unit sends a pre-charge contactor closing command. If no feedback from the charging contactor auxiliary contact closing is received within 2 seconds, the pre-charge contactor is determined to be engaged.

[0029] In a further preferred embodiment, if the control unit detects a main contactor engagement fault, and the control unit receives feedback from the main contactor engagement without issuing a closing command when the main circuit breaker is closed, and simultaneously the intermediate circuit voltage is lower than the main contactor engagement threshold, and the effective value of the four-quadrant module current is greater than the threshold or there is a transient overcurrent fault in the four-quadrant module input, it is determined to be a genuine main contactor engagement fault. At this time, the main circuit breaker is disconnected, isolating all converters in that section or rack to protect the transformer and converter safety. The logic of the main contactor engagement detection is that the traction control unit sends a main contactor engagement command, and if no feedback from the main contactor auxiliary contact closure is received within 2 seconds, it is determined that the main contactor is engaged.

[0030] In a further preferred embodiment, the auxiliary switch feedback method is implemented through normally open contact one and normally open contact two. The control unit sends a closing contactor command, and the opening and closing control switch in the control unit closes, causing the main contacts of the contactor to close. At the same time, normally open contact one and normally open contact two should also close. The control unit receives a high-level feedback signal from the contactor and determines whether the contactor is normal through protection logic. If a pre-charging contactor jamming fault or a main contactor jamming fault is determined, the number of self-reset detections of the traction system is increased. If the fault cannot be eliminated, it is determined to be a true jamming fault.

[0031] In a further preferred embodiment, the auxiliary switch feedback method is implemented through normally open contact one and normally open contact three. The control unit sends a disconnect contactor command, and the opening and closing control switch in the control unit is opened, causing the main contacts of the contactor to open. At the same time, normally open contact one and normally open contact three should also be opened. The control unit receives a low-level feedback signal from the contactor and determines whether the contactor is normal through protection logic. If a pre-charging contactor jamming fault is determined, there is basically no current in the pre-charging circuit after the main contactor is closed, which will not cause impact or overheating to the pre-charging circuit components. Therefore, the locomotive is allowed to continue running after a pre-charging contactor jamming fault.

[0032] This invention mainly describes three aspects: contactor status feedback detection method, contactor feedback status detection and judgment strategy, and contactor card opening / closing fault protection strategy. Without increasing hardware costs or algorithm complexity, this invention achieves accurate judgment of contactor card opening / closing faults, reducing the probability of false alarms. It focuses on how to reduce the fault level of contactor faults on locomotive operational safety, maximizing traction / braking force while ensuring safe and reliable locomotive operation. This facilitates accurate judgment of contactor faults and reduces the fault level and number of contactor faults.

[0033] This invention focuses on contactor fault diagnosis, which can improve the accuracy of converter fault diagnosis by combining detection methods and control strategies.

[0034] The present invention has the following beneficial effects: (1) Using a parallel connection of normally open auxiliary switches in the detection circuit to feed back the contactor status can reduce the false alarm rate of contactor jamming fault; using a series connection of normally open auxiliary switches in the detection circuit to feed back the contactor status can reduce the false alarm rate of contactor jamming fault; adding a reset condition control strategy to the control unit can reduce the false alarm rate of fault; the control strategy of the control unit detecting the status of the contactor auxiliary switch and simultaneously detecting whether the voltage and current values ​​in the circuit meet the threshold can reduce the false alarm rate of fault.

[0035] (2) Based on the fault level of the main contactor and the pre-charge contactor card opening and closing fault, the detection method and the control strategy are combined in different ways to further improve the accuracy of the fault diagnosis of the contactor for the traction converter and minimize the fault level. At the same time, the comprehensive diagnosis method has simple judgment logic, low occupancy of the control unit's computing resources, and improves the overall performance of the traction system and the locomotive's operating efficiency. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This diagram illustrates the main circuit schematic of the traction converter of the present invention.

[0039] Figure 2 This diagram illustrates the two normally open parallel connection configuration of the contactor detection circuit of the present invention.

[0040] Figure 3 This diagram illustrates the two normally open circuits connected in series in the contactor detection circuit of the present invention.

[0041] In the diagram: 1-Pantograph, 2-Main circuit breaker, 3-Main transformer, 4-Pre-charge contactor, 5-Pre-charge resistor, 6-Main contactor, 7-Four-quadrant module, 8-Intermediate support capacitor, 9-Slow release resistor, 10-Normally open I, 11-Normally open II, 12-Normally open III, 13-Coil, 14-Control unit, 15-Opening feedback, 16-Opening control. Detailed Implementation

[0042] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0043] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" 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 connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0044] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0045] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Example

[0046] A comprehensive diagnostic method for contactor locking / unlocking faults in traction converters is disclosed. This method employs a two-way normally open auxiliary switch feedback mechanism in the contactor detection circuit, and detects the locking / unlocking fault through the control unit 14. Locking / unlocking refers to the control unit 14 sending a closing command to the contactor, but receiving a feedback signal from the contactor indicating separation. Based on logical judgment, the control unit 14 determines that the contactor cannot close and reports a lock / unlocking fault.

[0047] "Stuck" refers to a situation where the control unit 14 sends a disconnect command to the contactor, but receives a feedback signal from the contactor indicating that it is closed. The control unit 14 then determines that the contactor cannot be disconnected based on its logic and reports a contactor stuck fault.

[0048] The auxiliary switch feedback method is a parallel connection. Because the converter has no power input, the traction / braking force of that axle is lost. Taking the HXD2 eight-axle locomotive as an example, 1 / 8 of the power is lost, but 7 / 8 of the power is utilized for sustainable operation.

[0049] The working principle is as follows: In this embodiment, the locomotive consists of two sections, A and B, each equipped with one main transformer and 3-4 independently controlled traction converters for each axle. Under normal operating conditions, the locomotive's electric drive system can provide traction / braking force for all eight axles.

[0050] By using two normally open auxiliary switches in parallel in the contactor detection circuit, such as... Figure 2 As shown in the figure, the control unit 14 sends a command to close the contactor. The opening and closing control 16 switch in the control unit 14 closes, the contactor coil 13 is energized, and the main contacts of the contactor close. At the same time, the normally open contacts 10 and 11 should also close. The control unit 14 receives a high-level feedback signal from the contactor and uses the protection logic to determine whether the contactor is functioning properly.

[0051] Because normally open contacts 10 and 11 are connected in parallel in the DC110+ circuit, if either one is closed, the control unit 14 will receive a high-level signal, which determines that the contactor sends a command and receives a feedback signal. This avoids the card failure caused by one of the normally open contacts being unstable and not closing.

[0052] If a fault is determined to be a card-type fault in pre-charging contactor 4 and a card-type fault in main contactor 6, the control strategy increases the number of self-reset checks in the traction system. If the fault cannot be eliminated, it is determined to be a true card-type fault. Because there is no power input to the converter, the traction / braking force of that axle is lost. Taking an eight-axle locomotive as an example, 1 / 8 of the power is lost, but the remaining 7 / 8 of the power allows for continued operation. Example

[0053] A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter is provided. The contactor detection circuit adopts a two-way normally open auxiliary switch feedback method, and the control unit 14 detects card opening / closing faults. The auxiliary switch feedback method is a series connection.

[0054] Control unit 14 detected a pre-charge contactor 4 engaging fault that could not be eliminated, and determined it to be a genuine pre-charge contactor 4 engaging fault.

[0055] If the control unit 14 detects a jamming fault in the main contactor 6, and the main circuit breaker 2 is not closed, the control unit 14 receives feedback from the main contactor 6 closing even though it does not issue a closing command. It determines that the contactor auxiliary mechanism has falsely reported a jamming fault. At this time, the converter of that shaft is isolated, resulting in the loss of traction / braking force of that shaft.

[0056] If the control unit 14 detects a main contactor 6 engaging fault, and if the main circuit breaker 2 is closed, but the control unit 14 does not issue a closing command but receives feedback that the main contactor 6 is closed, and the intermediate circuit voltage is lower than the main contactor 6 closing threshold value, and the effective value of the current of the four-quadrant module 7 is greater than the threshold or there is a momentary overcurrent fault in the input of the four-quadrant module 7, it is determined to be a real main contactor 6 engaging fault. At this time, the main circuit breaker 2 is disconnected, isolating all converters in this section or rack to protect the transformer and converter safety.

[0057] like Figure 3 As shown, the control unit 14 sends a disconnect contactor command. The opening and closing control 16 switch in the control unit 14 is opened, the contactor coil 13 is de-energized, and the main contacts of the contactor are opened. At the same time, the normally open contacts 10 and 12 should also be opened. The control unit 14 receives a low-level feedback signal from the contactor and determines whether the contactor is normal through the protection logic.

[0058] Because normally open circuit 10 and normally open circuit 312 are connected in series in the DC110+ circuit, if either one is disconnected, the control unit 14 will receive a low-level signal, which will determine that the contactor sends a command and receives a feedback signal. This avoids the problem of a fault caused by one of the auxiliary switches not being disconnected due to instability.

[0059] If the pre-charging contactor 4 is determined to be stuck, analysis shows that after the main contactor 6 closes, there is essentially no current in the pre-charging circuit, which will not cause impact or overheating to the components of the pre-charging circuit. Therefore, the control strategy after the pre-charging contactor 4 fails to engage allows the locomotive to continue operating. Taking an eight-axle locomotive as an example, there will be no loss of power, and it can continue to operate.

[0060] After the main contactor 6 closes, there is essentially no current in the pre-charging circuit, which will not cause impact or overheating to the components of the pre-charging circuit. Therefore, the control strategy after the pre-charging contactor 4 fails to engage allows the locomotive to continue operating.

[0061] Example 3: Based on Example 2, the judgment of the main contactor 6 engagement failure is divided into two levels of fault handling.

[0062] In a Level 1 fault, when the main circuit breaker 2 is not closed, the control unit 14 receives feedback that the main contactor 6 is closed without issuing a closing command. This is determined to be a false alarm of a jamming fault in the contactor auxiliary mechanism, requiring isolation of the converter on that axle, resulting in a loss of traction / braking power for that axle. Taking an eight-axle locomotive as an example, 1 / 8 of the power is lost, but the remaining 7 / 8 of the power allows for continued operation.

[0063] A level 2 fault occurs when the main circuit breaker 2 is closed, but the control unit 14 receives feedback from the main contactor 6 that the main contactor 6 is closed without issuing a closing command. Simultaneously, the intermediate circuit voltage is lower than the main contactor 6 closing threshold, and the effective value of the four-quadrant current is greater than the threshold, or there is a four-quadrant input instantaneous overcurrent fault. This is determined to be a genuine main contactor 6 jamming fault. The main circuit breaker 2 must be disconnected to isolate all converters in that section or frame, protecting the transformer and converters. Taking an eight-axle locomotive as an example, half the power is lost, and the remaining half is used for operation.

[0064] The present invention has the following advantages: 1. By using multiple normally open auxiliary switches in parallel in the contactor detection circuit, the redundancy of contactor closure feedback is increased, which can reduce the false alarm rate of contactor card failure due to unstable feedback from a single auxiliary switch.

[0065] 2. By using multiple normally open auxiliary switches in series in the contactor detection circuit, the redundancy of contactor disconnection feedback is increased, which can reduce the false alarm rate of contactor jamming due to unstable feedback from a single auxiliary switch.

[0066] 3. The control strategy for the card-splitting faults of pre-charging contactor 4 and main contactor 6 increases the number of self-reset detections of the traction system, and makes multiple judgments to eliminate false alarms or interference.

[0067] 4. The control strategy after a pre-charging contactor 4 fails to engage allows the locomotive to continue operating without causing power loss or affecting track safety.

[0068] 5. The control strategy for main contactor 6 engaging faults adds judgment conditions, with two levels of fault protection. It can distinguish between false alarms and genuine engaging faults. If a false alarm occurs, the shaft can be isolated for continued operation without affecting line safety. If a genuine engaging fault occurs, the main circuit breaker 2 is tripped, isolating all converters in that section or rack, protecting the transformer and converters.

[0069] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A comprehensive diagnostic method for contactor card opening / closing faults in traction converters, characterized in that: The traction converter obtains electrical energy from the overhead contact line and converts the single-phase AC power on the secondary side of the transformer into the DC power required by the system through the input-side circuit contactor and rectifier. In the main circuit, the contactor is used to control the connection and disconnection of the pre-charging circuit and the main circuit, and also undertakes the function of fault disconnection and isolation of the converter system. The electrical connection of a contactor consists of three parts: the actuating mechanism, the driving mechanism, and the auxiliary mechanism; among which the actuating mechanism is responsible for connecting and disconnecting the circuit and carrying the normal operating current. The control unit (14) in the drive mechanism controls the on and off of the coil, and the electromagnetic energy generated by the coil is converted into mechanical energy that drives the action mechanism. The auxiliary mechanism refers to the micro switch, which consists of multiple normally open and normally closed auxiliary switches interlocked with the actuating mechanism. The auxiliary switch is connected to the low-voltage detection circuit. The actuating mechanism drives the auxiliary switch to operate. The control unit (14) receives feedback on the on / off status of the auxiliary switch to determine the open / closed status of the contactor. The detection circuit adopts a normally open auxiliary switch feedback method. The control unit (14) receives the feedback of the on / off status of the auxiliary switch to determine the contactor card opening / closing fault.

2. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 1, characterized in that: The auxiliary switch feedback method is a parallel connection.

3. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 1, characterized in that: The auxiliary switch feedback method is a series connection.

4. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 2, characterized in that: After the control unit (14) detects a carding fault, it increases the number of self-reset detections of the traction system. If the fault cannot be eliminated, it is determined to be a real carding fault.

5. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 3, characterized in that: The control unit (14) detects a pre-charging contactor (4) engagement failure and the failure cannot be eliminated. It determines that the pre-charging contactor (4) engagement failure is real. At this time, the traction converter maintains the contactor state and continues to operate without causing power loss.

6. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 3, characterized in that: If the control unit (14) detects a jamming fault in the main contactor (6), and the main circuit breaker (2) is not closed, the control unit (14) does not issue a closing command but receives feedback from the main contactor (6) closing. It is determined that the contactor auxiliary mechanism falsely reports a jamming fault. At this time, the shaft converter is isolated, and the traction / braking force of the shaft is lost.

7. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 3, characterized in that: If the control unit (14) detects a main contactor (6) engagement fault, and the control unit (14) receives feedback from the main contactor (6) closing even though the main circuit breaker (2) is closed, and the intermediate circuit voltage is lower than the main contactor (6) closing threshold value, and the effective value of the current of the four-quadrant module (7) is greater than the threshold or there is a momentary overcurrent fault in the input of the four-quadrant module (7), it is determined to be a real main contactor (6) engagement fault. At this time, the main circuit breaker (2) is disconnected, and all converters in the section or rack are isolated to protect the transformer and converter safety.

8. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 4, characterized in that: The auxiliary switch feedback method is implemented through normally open one (10) and normally open two (11). The control unit (14) sends a closing contactor command, and the opening and closing control (16) switch in the control unit (14) closes, so that the main contact of the contactor closes. At the same time, normally open one (10) and normally open two (11) of the contactor should both close. The control unit (14) receives the high-level signal of the contactor feedback and judges whether the contactor is normal through the protection logic. If the pre-charging contactor (4) is found to be stuck and the main contactor (6) is found to be stuck and the number of self-reset detections of the traction system is increased. If the fault cannot be eliminated, it is determined to be a real stuck and split fault.

9. A comprehensive diagnostic method for contactor card opening / closing faults in a traction converter according to claim 5, characterized in that: The auxiliary switch feedback method is implemented through normally open one (10) and normally open three (12). The control unit (14) sends a disconnect contactor command, and the opening and closing control (16) switch in the control unit (14) is opened, so that the main contact of the contactor is disconnected. At the same time, normally open one (10) and normally open three (12) of the contactor should be disconnected. The control unit (14) receives the low-level signal of the contactor feedback and judges whether the contactor is normal through the protection logic. If the pre-charging contactor (4) is found to be stuck, there is basically no current in the pre-charging circuit after the main contactor (6) is closed. It will not cause impact or overheating to the pre-charging circuit components. Therefore, the locomotive is allowed to continue running after the pre-charging contactor (4) is stuck.

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