Crane Travel Inverter Torque Control for Vibration Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Quay cranes experience deformation and vibration during travel and stop due to misalignment of travel devices, leading to swinging of the boom, which necessitates waiting for the swinging to settle before loading or unloading operations can be performed.
Innovation Solution
Incorporating torque measurement units and control units in the inverters of the travel devices to adjust the rotation speed command, ensuring that higher torque values result in greater reduction ratios, thereby minimizing misalignment and strain in the crane structure, and applying brakes only after the rotation speeds are maintained at zero and torques are balanced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sea-side travel device and land-side travel device are controlled independently with the same speed command, then the crane can travel in the travel direction, but the sea-side travel device falls behind the land-side travel device causing misalignment
Solution Approach 1:
The control unit receives detection results from detection units that monitor the actual positions of both travel devices, and adjusts the speed commands accordingly to maintain proper alignment between the sea-side and land-side travel devices
Solution Approach 2:
The system changes the speed command parameter dynamically based on the detected alignment state, giving different speed commands to the sea-side and land-side travel devices to compensate for the weight difference and maintain proper positioning
2Duration of action of moving object
If the crane structure is misaligned due to travel device positioning errors, then the crane can continue traveling, but rotation moments are generated causing deformation and vibration
Solution Approach 1:
The control unit performs preliminary correction by adjusting the speed commands to travel devices before significant misalignment occurs, preventing the generation of harmful rotation moments and deformation in the crane structure
Solution Approach 2:
The system converts the harmful effect of weight difference causing misalignment into a beneficial control signal, where the detection unit measures the misalignment and the control unit uses this information to adjust speed commands and maintain proper alignment
3Reliability
If brakes are applied before complete stop to prevent wind movement, then the crane can be secured, but vibration occurs due to residual strain in the misaligned structure
Solution Approach 1:
The control unit performs preliminary alignment correction by adjusting travel device positions before braking is applied, ensuring the crane structure is properly aligned and free of residual strain when the brakes are engaged, thereby preventing vibration
Data Source
AI summary
Provided is a crane which can suppress deformation and vibration of a crane structure in travel and stop of the crane. Inverters are installed respectively in travel devices which are arranged on the opposite sides with a gap in a transverse direction. Each of the inverters independently measures a torque generated in a motors to which the inverter is connected and reduces the rotation speed in the command from a controller to the motor such that the greater the measured torque is, the greater a ratio of reduction is.