Electrical fault diagnosis method for deviation of heavy-duty travelling crane

Abstract

The invention discloses an electrical fault diagnosis method for deviation of a heavy crane, which comprises the following steps of: respectively driving walking motors on the left and right sides to walk by two groups of frequency converters of the heavy crane, respectively controlling the first group of frequency converters and the second group of frequency converters to operate, and respectively observing the walking state of the crane; when any one of the frequency converters operates independently and when the two frequency converters operate at the same time, the traveling crane does not deviate, it is judged that the two frequency converters have assembly synchronization faults; the walking motors are operated through frequency converters respectively, and the consistency of motion curve parameters of the two walking motors is detected; and comparing the running states of the two groups of frequency converter driving walking motors, and verifying the consistency of the running states of the two groups of frequency converter driving walking motors. According to the method, the systematized diagnosis process of segmented operation isolation-parameter consistency detection-operation state verification is constructed, so that the deviation problem caused by electrical asynchronization can be accurately detected, and the diagnosis precision and efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of fault diagnosis technology for crane equipment, and specifically to a method for diagnosing electrical faults in heavy-duty cranes that lead to deviation. Background Technology

[0002] Heavy-duty overhead cranes are widely used in industrial settings such as metallurgy, ports, warehousing, and large manufacturing workshops, serving as crucial equipment for material handling and process coordination. The crane's traveling mechanism typically employs a multi-motor drive system, with two sets of frequency converters driving the traveling motors on the left and right sides of the crane. Synchronous control of these motors ensures the crane travels smoothly and linearly along the track. Theoretically, the traveling motors on both sides should maintain consistent speeds and synchronized start and stop times to ensure the crane's trajectory coincides with the track's centerline. However, in practical applications, factors such as frequency converter parameter drift, aging of on-site electrical components, installation and debugging deviations, and differences in drive link response can easily lead to asynchrony between the left and right traveling motors. If one side's traveling motor lags behind or leads, the crane will deviate from its intended direction, causing continuous friction between the wheel flanges and the track side, resulting in what is commonly known in the industry as "rail biting."

[0003] "Rail wear" not only causes abnormal wear between the wheels and rails, shortening their service life, but can also lead to increased noise, increased running resistance, and increased equipment vibration during operation. In severe cases, it can even cause major safety hazards such as train jamming and derailment. Therefore, timely elimination of deviation problems caused by electrical asynchrony is of great significance for ensuring the safe and reliable operation of the train system. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a fault diagnosis method that can conveniently and accurately diagnose and eliminate vehicle deviation caused by electrical problems, thereby improving equipment maintenance efficiency.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for diagnosing electrical faults in heavy-duty overhead cranes, wherein the heavy-duty overhead crane is driven by two sets of frequency converters, which drive the left and right travel motors respectively, includes the following steps: (1) Control the operation of the first group of frequency converters and the second group of frequency converters respectively, and observe the travel status of the crane. When any group of frequency converters runs independently, the crane does not run off track. However, when both groups of frequency converters run simultaneously, the crane does run off track. Therefore, it is determined that there is a component synchronization fault in the two groups of frequency converters. (2) Operate the walking motors separately through the frequency converters and test the consistency of the motion curve parameters of the two walking motors; (3) Compare the operating status of the two sets of frequency converters driving the walking motors to verify the consistency of their operating status.

[0006] In this invention, by firstly operating the vehicle system in segments, faults can be quickly located at the system coordination level, rather than at the single-machine function level, thus avoiding the limitations that may exist in traditional methods. Secondly, verification is performed at two levels: the source of the execution command (the motion curve parameters of the travel motor) and the source of drive execution (the frequency converter control), forming a closed-loop diagnostic system that ensures the comprehensiveness and accuracy of the diagnosis, thereby improving the precision and efficiency of fault diagnosis.

[0007] As an optimization, in step (2), the consistency check of motion curve parameters includes: confirming that the acceleration time parameters, deceleration time parameters, and acceleration / deceleration curve types of the two travel motors are consistent under the same conditions. The consistency of acceleration time parameters and deceleration time parameters ensures that the acceleration and deceleration processes of the two travel motors are synchronized, directly affecting the response speed and coordination of the two motors during operation; the consistency of acceleration / deceleration curve types ensures that the two motors use the same control curve during acceleration and deceleration. This avoids inconsistent dynamic responses of the vehicle during startup or shutdown, which could lead to synchronization problems and ensures the smoothness and synchronization of motor movement.

[0008] As an optimization, in step (3), the running status comparison includes: reading the speed feedback values ​​of the two walking motors in real time, calculating the real-time difference between the speed values ​​of the two walking motors, and determining whether the speed error is within the preset threshold range. By reading the speed feedback of the two walking motors, the speed difference between the motors can be intuitively grasped, the synchronization status of the motors can be tracked in real time, and by calculating the speed difference and comparing it with the preset threshold, synchronization problems that exceed the normal range can be effectively identified.

[0009] As an optimization, in step (3), the operating status comparison includes: during the vehicle start-up, constant speed travel, and braking stages, the output current data of each group of frequency converters and / or the output torque data of the travel motor are collected and compared respectively. In any stage, if the output current data of any group of frequency converters or the output torque data of the travel motor show the following situation, it is determined that the output of that group of frequency converters is abnormal: (a) The output current continuously exceeds the threshold of the set rated current range; (b) The set threshold for the output torque to continuously deviate from the normal operating range; (c) The fluctuation range of the output current or output torque exceeds the predetermined fluctuation threshold.

[0010] By collecting and comparing the output current of the frequency converter and the output torque of the motor, the operating status between the frequency converter and the motor can be monitored comprehensively. The current output of the frequency converter directly affects the operation of the motor, while the output torque of the motor reflects the actual workload and performance of the motor. Combining and comparing the status of these two data points can provide more comprehensive data support for fault diagnosis.

[0011] As an optimization, if no fault is found after completing all steps, an auxiliary diagnostic mode is executed, including: using an oscilloscope to measure the output voltage and frequency waveforms of the two inverters and comparing their consistency; and checking whether the encoder feedback signal of the travel motor is normal. Using an oscilloscope to compare the output voltage and frequency waveforms can reveal some subtle synchronization issues, especially inconsistencies in frequency control by the inverters; checking whether the encoder feedback signal is normal can determine whether the actual operating state of the motor matches expectations.

[0012] Compared with existing technologies, this invention constructs a systematic diagnostic process of segmented operation isolation, parameter consistency detection, and operation status verification, which can accurately detect deviation problems caused by electrical asynchrony; the consistency analysis of key parameters such as motor acceleration and deceleration time, output current, and torque optimizes the fault diagnosis process, realizes comprehensive diagnosis from control commands to execution results, and thus improves diagnostic accuracy and efficiency. Detailed Implementation

[0013] The electrical fault diagnosis method for heavy-duty crane deviation in this specific embodiment involves the heavy-duty crane being driven by two sets of frequency converters, which respectively drive the left and right travel motors. The method includes the following steps: (1) Control the operation of the first group of frequency converters and the second group of frequency converters respectively, and observe the travel status of the crane. When any group of frequency converters runs independently, the crane does not run off track. However, when both groups of frequency converters run simultaneously, the crane does run off track. Therefore, it is determined that there is a component synchronization fault in the two groups of frequency converters. (2) Operate the walking motors separately through the frequency converters and test the consistency of the motion curve parameters of the two walking motors; (3) Compare the operating status of the two sets of frequency converters driving the walking motors to verify the consistency of their operating status.

[0014] In step (2), the consistency detection of motion curve parameters includes: confirming that the acceleration time parameters, deceleration time parameters and acceleration / deceleration curve types of the two walking motors are consistent under the same conditions.

[0015] In step (3), the running status comparison includes: reading the speed feedback values ​​of the two walking motors in real time, calculating the real-time difference between the speed values ​​of the two walking motors, and determining whether the speed error is within the preset threshold range.

[0016] In step (3), the operation status comparison includes: during the vehicle start-up, constant speed travel, and braking stages, the output current data of each group of frequency converters and / or the output torque data of the travel motor are collected and compared respectively. If the output current data of any group of frequency converters or the output torque data of the travel motor show the following situation at any stage, it is determined that the output of that group of frequency converters is abnormal: (a) The output current continuously exceeds the threshold of the set rated current range; (b) The set threshold for the output torque to continuously deviate from the normal operating range; (c) The fluctuation range of the output current or output torque exceeds the predetermined fluctuation threshold.

[0017] If no fault is found after all steps have been performed, the auxiliary diagnostic mode is executed, including: using an oscilloscope to measure the output voltage and frequency waveforms of the two inverters and comparing their consistency; and checking whether the encoder feedback signal of the walking motor is normal.

[0018] Taking a double-girder bridge crane (heavy-duty overhead crane) as an example, its trolley traveling mechanism is driven by two frequency converters, A and B (i.e., the first group and the second group of frequency converters), which drive the traveling motors on the left and right sides respectively.

[0019] Before starting fault diagnosis, mechanical troubleshooting must be performed first; this is the prerequisite for all electrical diagnostics. On-site maintenance personnel should check: whether the track span, parallelism, and elevation meet design specifications; whether the track joint gaps are normal and whether there is any height misalignment; whether the diameter of the trolley wheels is within the allowable tolerance range, and whether the wheel flanges are severely worn or deformed; and whether the wheel bearings are intact and adequately lubricated. Only after confirming that all the above mechanical factors are normal can the following electrical diagnostic steps be performed.

[0020] The core purpose of segmented operation and fault isolation is to determine whether the deviation problem originates from a fault in one side of the drive system or a coordinated fault between the two drive systems. The first set of inverters is tested individually, with only inverter A and its driven left-side motor powered on, while inverter B is in standby mode with power off. The trolley is moved forward (or backward) approximately 10-20 meters, and its trajectory is carefully observed throughout. If the trolley travels in a straight line along the track without any deviation or "rail-biting" sound, it is recorded as "Set A is operating normally." The second set of inverters is tested individually, again with only inverter B and its driven right-side motor running, while inverter A is powered off. The above operation is repeated, and observations are recorded. If the trolley travels in a straight line, it is recorded as "Set B is operating normally." Both sets of inverters, A and B, are then started simultaneously, driving the trolley along the same track section. If the trolley is observed to significantly deviate to one side (e.g., to the left), accompanied by friction noise from the wheels against the track, then the fault is determined to be a problem with the synchronization and coordination between inverters A and B.

[0021] After determining that the problem was a synchronization issue, the motion curve parameters of the motor were checked: Acceleration and deceleration time: Check the time required to accelerate from 0Hz to 50Hz and the time required to decelerate from 50Hz to 0Hz. It is essential to ensure that these two time parameters are set exactly the same for both inverters, for example, both should be set to 10 seconds. Any difference will cause one motor to reach the target speed while the other is still accelerating at the moment of startup and shutdown, thus causing the motor to run off track.

[0022] Acceleration / deceleration curve type: Check and ensure that the curve types selected by inverters A and B are consistent. If the acceleration / deceleration curves are inconsistent, even if the acceleration / deceleration time is set the same, the actual torque and speed change rate of the motor will be different in the initial and final stages of acceleration, resulting in dynamic asynchrony.

[0023] Speed ​​Synchronization Verification: With the vehicle unloaded and at low speed, start inverters A and B simultaneously. Read the "output frequency" (Hz) or "actual motor speed" (rpm) from inverters A and B in real time via their panels, and calculate the real-time speed difference between the two sides. For example, if the motor speed on side A is 1450 rpm and on side B is 1440 rpm, the difference is 10 rpm. Determine if this difference is within a preset threshold range. This threshold can be set according to the equipment's accuracy requirements, for example, 0.5% of the rated speed (approximately 7.25 rpm for a 1450 rpm motor). If the difference consistently exceeds the threshold, it indicates a speed asynchrony.

[0024] Current / torque synchronization verification: During the three typical stages of vehicle start-up, constant speed travel, and braking, the "output current" (A) and / or "output torque" (%) of inverters A and B are read and recorded in real time through the inverter panel. During the start-up stage, observe the peak current on both sides. Under normal circumstances, the starting current on both sides should be similar in magnitude and have a consistent trend. If the current on one side is significantly higher than the other side and persists for a long time, it may indicate that the motor on that side is sluggish or that the inverter torque boost parameter is set too high. During the constant speed travel stage, observe the steady-state operating current on both sides. The currents on both sides should be very close and stable. During the braking stage, observe the current during braking. Inconsistency may indicate a problem with the braking unit or resistor configuration. If the current / torque data on one side is found to be consistently high or fluctuates drastically at any stage, it can be determined that the inverter-motor system output on that side is abnormal.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described with reference to preferred embodiments, those skilled in the art should understand that various changes in form and detail can be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for diagnosing electrical faults in heavy-duty cranes, wherein the heavy-duty crane is driven by two sets of frequency converters, which respectively drive the left and right travel motors, characterized in that: Includes the following steps: (1) Control the operation of the first group of frequency converters and the second group of frequency converters respectively, and observe the travel status of the crane. When any group of frequency converters runs independently, the crane does not run off track. However, when both groups of frequency converters run simultaneously, the crane does run off track. Therefore, it is determined that there is a component synchronization fault in the two groups of frequency converters. (2) Operate the walking motors separately through the frequency converters and test the consistency of the motion curve parameters of the two walking motors; (3) Compare the operating status of the two sets of frequency converters driving the walking motors to verify the consistency of their operating status.

2. The electrical fault diagnosis method for heavy-duty vehicle deviation according to claim 1, characterized in that: In step (2), the consistency detection of motion curve parameters includes: confirming that the acceleration time parameters, deceleration time parameters and acceleration / deceleration curve types of the two walking motors are consistent under the same conditions.

3. The electrical fault diagnosis method for heavy-duty vehicle deviation according to claim 1, characterized in that: In step (3), the running status comparison includes: reading the speed feedback values ​​of the two walking motors in real time, calculating the real-time difference between the speed values ​​of the two walking motors, and determining whether the speed error is within the preset threshold range.

4. The electrical fault diagnosis method for heavy-duty vehicle deviation according to claim 1, characterized in that: In step (3), the operation status comparison includes: during the vehicle start-up, constant speed travel, and braking stages, the output current data of each group of frequency converters and / or the output torque data of the travel motor are collected and compared respectively. If the output current data of any group of frequency converters or the output torque data of the travel motor show the following situation at any stage, it is determined that the output of that group of frequency converters is abnormal: (a) The output current continuously exceeds the threshold of the set rated current range; (b) The set threshold for the output torque to continuously deviate from the normal operating range; (c) The fluctuation range of the output current or output torque exceeds the predetermined fluctuation threshold.

5. The electrical fault diagnosis method for heavy-duty vehicle deviation according to any one of claims 1 to 4, characterized in that: If no fault is found after all steps have been performed, the auxiliary diagnostic mode is executed, including: using an oscilloscope to measure the output voltage and frequency waveforms of the two inverters and comparing their consistency; and checking whether the encoder feedback signal of the walking motor is normal.