Bridge Crane Inverter Control for Sensorless Anti-Sway Operation
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Solution Overview
Problem
Existing anti-sway technologies for bridge cranes require complex system parameters that are difficult to measure, necessitating motor position sensors, which increase cost and implementation difficulty, and often rely on swing angle estimators that are not cost-effective.
Innovation Solution
A full-time anti-sway control method for bridge cranes using an inverter structure that calculates frequency change curves and correction amounts based on rope length and system parameters, eliminating the need for motor position sensors and enabling versatile, low-cost, and easy-to-implement anti-sway control across various crane operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor position sensors (encoder or Hall sensor) are installed to achieve anti-sway control, then anti-sway function can be implemented, but construction cost and implementation difficulty increase
Solution Approach 1:
The patent extracts and eliminates the requirement for motor position sensors from the anti-sway control system. By using the inverter's existing current detection capabilities and implementing a novel control algorithm, the system achieves anti-sway functionality without needing encoders or Hall sensors, thereby reducing hardware complexity and cost while maintaining the core anti-sway function
Solution Approach 2:
The patent replaces the mechanical sensing approach (using encoders or Hall sensors to detect motor position) with an electrical control approach (using inverter current detection and mathematical algorithms to estimate and control swing). This substitution eliminates the need for additional mechanical sensors while achieving the same control objective
2Device complexity
If swing angle estimators are used to replace image identifiers or angle sensors for cost considerations, then cost is reduced, but system parameters are difficult to measure and acquire
Solution Approach 1:
The patent makes the system self-sufficient by using the inverter's built-in current detection capabilities to automatically estimate swing angle and speed. The control algorithm utilizes readily available electrical parameters (current signals) instead of requiring separate mechanical measurements, enabling the system to self-determine swing state without external sensors or complex parameter acquisition processes
Solution Approach 2:
The patent transforms the measurement approach from mechanical parameters (angle, position) to electrical parameters (current). By detecting swing through current variations in the motor drive system, the patent converts an otherwise difficult-to-measure mechanical quantity into an easily measurable electrical quantity that is already available in the inverter control system
Data Source
AI summary
A full-time anti-sway control method of a bridge crane system based on an inverter structure includes steps of: receiving a specified high frequency and a frequency change time, calculating a time setting range according to a plurality of system parameters and a rope length information of the bridge crane system, selecting a time setting value within the time setting range, dividing the frequency change time into a plurality of time intervals according to the time setting value, adjusting an operation frequency command to change between a low frequency and the specified high frequency within the plurality of time intervals to generate a frequency change curve, calculating a frequency correction amount according to the frequency change curve and the rope length information, and superimposing the frequency change curve and the frequency correction amount to generate an anti-sway frequency command to drive the at least one motor.