Carrier-Signal Arc Monitoring for Short-Circuit Welding Control
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Solution Overview
Problem
Conventional short circuit gas metal arc welding (GMAW) processes face challenges in accurately predicting the state of the welding arc, particularly the moment of reignition after a short circuit, which can lead to spatter and weld puddle disturbances due to the dynamic nature of the arc.
Innovation Solution
The system injects a carrier signal into the control system to measure impedance by monitoring the phase angle between voltage and current, allowing for improved prediction and control of the welding arc state, including detection of short circuit conditions and adjustments to the reference parameters based on impedance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional short circuit GMAW processes are used, then the welding process is simple and easy to operate, but the accuracy of predicting welding arc state is poor leading to spatter and weld puddle disturbances
Solution Approach 1:
The patent introduces an intermediary carrier signal at a specific frequency (e.g., 100 Hz) that is superimposed on the welding current. This carrier signal acts as a mediator to probe the welding arc impedance without significantly disrupting the welding process. By measuring the phase angle between the injected carrier signal and the resulting current, the system can accurately predict arc state transitions while maintaining relatively simple hardware implementation.
Solution Approach 2:
The patent replaces direct mechanical/sensor-based arc state detection with an electrical measurement approach. Instead of using complex optical sensors or physical probes to monitor arc conditions, the system uses electrical impedance measurement through carrier signal injection. This substitution enables accurate arc state prediction while avoiding the complexity of mechanical or optical detection systems.
2Measurement precision
If the welding arc is monitored without carrier signal injection, then the control system is simple, but the detection precision of arc state transitions is insufficient
Solution Approach 1:
The patent employs periodic carrier signal injection at a specific frequency (e.g., 100 Hz) to continuously probe the welding arc impedance. This periodic action creates a measurable phase angle variation that directly correlates with arc state transitions. The periodic nature of the carrier signal enables consistent and reliable detection of arc conditions without requiring complex continuous monitoring systems.
Solution Approach 2:
The patent utilizes changes in electrical impedance parameters (specifically phase angle) to detect arc state transitions. By monitoring how the phase angle between the injected carrier signal and welding current changes, the system can accurately determine when arc state transitions occur (e.g., from short circuit to arc state). This parameter-based approach simplifies measurement while improving detection precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of impedance measurement and control, reducing spatter and disturbances by proactively managing the welding process, thereby improving the overall welding quality.
Implementation Method 1
measures a phase angle between a voltage signal and a current signal to determine an impedance of the welding arc at the carrier frequency
Data Source
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Figure 3A~3D
AI summary
Disclosed example welding power supplies include: power conversion circuitry configured to convert input power to welding power; and control circuitry configured to: control the power conversion circuitry based on a control loop and a reference parameter; add a carrier signal to the control loop, the carrier signal having a carrier frequency; measure an impedance at an output of the power conversion circuitry based on the carrier frequency; and control the reference parameter based on the impedance.