Welding Power Supply Current Ramping for Stable Stick Arc Control

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Solution Overview

Problem

Conventional electronic/inverter welding power sources lack the dynamic current responses necessary to replicate the high-quality welding characteristics of DC generators, particularly in stick welding applications, leading to suboptimal arc control and increased risk of electrode sticking during pipe welding.

Innovation Solution

A welding power supply with adjustable current ramping rates and a control circuit that dynamically adjusts the welding current based on voltage thresholds, allowing for increasing and decreasing ramp rates, hold amperages, and dwell times to mimic the response of a DC generator, thereby improving arc control and reducing electrode sticking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional electronic/inverter welding power sources are used, then device complexity is reduced and ease of manufacture is improved, but welding characteristics and arc control quality deteriorate compared to DC generators

Engineering Contradiction:
Improveease of manufactureVSAvoidwelding characteristics
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent copies the dynamic current response characteristics of DC generators by implementing adjustable current ramping rates and voltage-threshold-based control circuits in electronic/inverter welding power sources. The control circuit replicates the magnetic design behaviors of DC generators through software-controlled current adjustment, allowing the inverter power source to mimic the arc control qualities that make DC generators reliable for pipe welding applications

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent introduces dynamic current control by implementing adjustable current ramping rates that can increase or decrease based on voltage thresholds. The control circuit dynamically adjusts the welding current in real-time based on arc conditions, transforming the static current control of conventional inverters into a dynamic system that adapts to changing welding conditions, thereby achieving DC generator-like reliability

Inventive Principle:
Principle #15Dynamics

2Reliability

If DC generator welding machines are used, then arc control quality and welding characteristics are improved, but device complexity and cost increase

Engineering Contradiction:
Improvewelding characteristicsVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/magnetic control system of DC generators with an electronic control system. Instead of relying on the physical magnetic design and tap switches of DC generator magnetics, the invention uses electronic control circuits with voltage comparators and programmable logic to achieve the same current control effects, thereby reducing device complexity while maintaining welding characteristics

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameters from fixed magnetic tap settings to dynamically adjustable current ramping rates. By allowing the current ramping rate to be modified based on voltage thresholds and welding conditions, the system achieves the adaptability of DC generators through electronic parameter adjustment rather than fixed mechanical configurations, reducing overall device complexity

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If conventional inverter power sources with fixed current control are used, then device simplicity is maintained, but arc control precision and response to short circuit conditions deteriorate

Engineering Contradiction:
Improvedevice complexityVSAvoidarc control
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements feedback control by using voltage sensing circuits to monitor weld voltage and feed this information back to the control circuit. The control circuit compares the sensed voltage against threshold values and adjusts the current ramping rate accordingly, creating a closed-loop control system that precisely controls arc conditions. This feedback mechanism enables the system to detect short circuit conditions and respond with appropriate current adjustments, achieving high arc control precision without excessive complexity

Inventive Principle:
Principle #23Feedback

4Reliability

If dynamic current control with voltage thresholds is implemented, then arc control precision and welding reliability are improved, but device complexity and control circuit requirements increase

Engineering Contradiction:
Improvewelding reliabilityVSAvoidcontrol circuit
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the control function into distinct voltage threshold levels (first threshold, second threshold, third threshold) with specific current ramping rates assigned to each. This segmentation allows the complex control logic to be divided into manageable discrete states, making the control circuit implementation more straightforward while maintaining high welding reliability through precise threshold-based decision making

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3768455B1Welding power supplies having dynamic current responses
Publication Date: 2024.01.31 ILLINOIS TOOL WORKS INC
  • EP3768455B1 patent drawingFigure 1
  • EP3768455B1 patent drawingFigure 2~3A
  • EP3768455B1 patent drawingFigure 3B~3C

AI summary

Welding power supplies having dynamic current responses are disclosed. Example welding power supplies include: power conversion circuitry (102) configured to convert supply power to welding current; a voltage sense circuit (104) configured to measure an output voltage of the power conversion circuitry; and control circuitry (106) configured to: in response to detecting that the output voltage has decreased below a lower voltage limit: control an increasing ramp rate of the welding current output by the power conversion circuitry; and in response to detecting that the output voltage has increased above the lower voltage limit, control a decreasing ramp rate of the welding current output by the power conversion circuitry.