Voltage-Controlled Welding Loop for Low-Spatter Short-Circuit Clearing

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Solution Overview

Problem

Conventional gas metal arc welding (GMAW) systems experience high current levels during short circuit clearing, leading to increased spatter and inefficiencies in the welding process due to the linear response of voltage-controlled control loops.

Innovation Solution

Incorporating a slope parameter into the voltage-controlled control loop to adjust the output voltage based on the output current, reducing the voltage error and current response, thereby minimizing spatter by clearing short circuits at lower currents and reducing energy output during the clearing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If conventional voltage-controlled control loops are used in GMAW systems, then the control loop remains simple and stable, but high current levels occur during short circuit clearing leading to increased spatter

Engineering Contradiction:
ImprovespatterVSAvoidcontrol loop complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent introduces a slope parameter that dynamically adjusts the control loop's response characteristics. By modifying the relationship between voltage error and current output through this slope parameter, the system achieves lower current levels during short circuit clearing, thereby reducing spatter while maintaining the fundamental simplicity of the voltage-controlled architecture

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the voltage-controlled control loop responds linearly to short circuits, then the control response is predictable, but current levels become excessively high during short circuit clearing

Engineering Contradiction:
Improvecontrol response predictabilityVSAvoidcurrent level during short circuit clearing
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent transforms the static linear response into a dynamic response by introducing the slope parameter that adapts during the control process. This allows the system to maintain predictable behavior through controlled non-linearity, where the slope parameter modulates the current response based on the short circuit condition, achieving lower peak currents while preserving control reliability

Inventive Principle:
Principle #15Dynamics

3Loss of time

If high current is used to clear short circuits quickly, then short circuit clearing time is reduced, but spatter generation increases significantly

Engineering Contradiction:
Improveshort circuit clearing timeVSAvoidspatter generation
Core Design Contradiction:
Loss of timeVSObject-generated harmful factors

Solution Approach 1:

The patent employs feedback mechanisms where the slope parameter is adjusted based on the system's response to short circuit conditions. This feedback-controlled adaptation allows the system to clear short circuits efficiently by optimizing the current profile in real-time, reducing both clearing time and spatter generation through intelligent parameter modulation rather than brute-force high current

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3865241B1Systems and methods to control welding processes using a voltage-controlled control loop
Publication Date: 2024.06.19 ILLINOIS TOOL WORKS INC
  • EP3865241B1 patent drawingFigure 1
  • EP3865241B1 patent drawingFigure 2
  • EP3865241B1 patent drawingFigure 3~4

AI summary

An example welding-type power supply, includes: power conversion circuitry configured to convert input power to welding-type power; and control circuitry configured to: control the power conversion circuitry to output the welding-type power based on a voltage-controlled control loop; and in response to detecting an output voltage less than a threshold voltage: during a first state, control the voltage-controlled control loop based on a first value of a control parameter of the voltage-controlled control loop to increase a response rate of the voltage-controlled control loop; and during a second state following the first state, control the voltage-controlled control loop based on a second value of the control parameter, wherein the second value of the control parameter causes a reduction in energy output by the power conversion circuitry relative to the first state.