AC Arc Welding Bridge Circuit for Rapid Current Decay
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Solution Overview
Problem
Existing AC arc welding processes face challenges in rapidly reducing output current while minimizing leakage currents and spatter, particularly during short circuit transfer processes like surface tension transfer, where maintaining and re-establishing the arc between a consumable electrode and a workpiece is difficult.
Innovation Solution
The introduction of a high impedance path in the weld circuit of an AC welding machine, facilitated by a hybrid bridge circuit with main and auxiliary bridge configurations, allows for directional switching of the output current, enabling rapid decay of arc current to a regulated non-zero level, reducing spatter and facilitating easy re-establishment of the arc.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional AC welding processes are used to reduce output current, then current reduction is achieved, but leakage currents and spatter increase while arc re-establishment becomes difficult
Solution Approach 1:
The patent introduces an auxiliary bridge circuit as an intermediary component between the main bridge circuit and the welding output. This auxiliary circuit provides a controlled high impedance path that acts as a mediator to rapidly reduce current while preventing harmful effects. The auxiliary bridge circuit with its switching devices and resistors creates a controlled current decay path that eliminates spatter and leakage currents that would otherwise occur during rapid current reduction.
Solution Approach 2:
The patent dynamically changes the impedance parameter of the welding circuit by switching between different bridge configurations. During normal welding, the circuit operates in low impedance mode for stable arc. During droplet transfer, the auxiliary bridge circuit is activated to switch the circuit to high impedance mode, enabling rapid current decay. This parameter change allows controlled current reduction without producing harmful spatter or leakage currents.
2Speed
If output current is rapidly reduced to zero, then current decay is achieved, but arc re-establishment becomes difficult
Solution Approach 1:
The patent applies preliminary action by controlling the current decay to stop at a regulated non-zero level rather than allowing it to reach zero. The auxiliary bridge circuit with its switching devices and resistors is configured to maintain a minimal current flow during the decay process. This preliminary control ensures that the arc remains partially sustained and can easily re-establish after droplet transfer, improving reliability while achieving rapid current decay.
3Adaptability or versatility
If bridge circuit topologies are added to provide AC welding capability, then welding flexibility is improved, but device complexity increases
Solution Approach 1:
The patent merges the auxiliary bridge circuit with the existing main bridge circuit topology. The auxiliary circuit is integrated into the same power source housing and control system, sharing common components where possible. This merging approach provides AC welding capability and rapid current decay functionality without creating a completely separate complex system, thus improving versatility while controlling device complexity.
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 solution effectively reduces spatter during the transfer of molten metal balls and ensures reliable re-establishment of the arc, improving the efficiency and control of the welding process.
Implementation Method 1
The auxiliary bridge circuit may include, for example, at least two switching transistors and at least one resistor. The resistance value of the at least one resistor may be less than two ohms or less than one ohm... configured to introduce a high impedance path between the power conversion circuit and the welding output circuit path
Implementation Method 2
A half-bridge topology may be used in a welding power source having dual output current paths configured to share a common path, such that each output can induce a flow of opposite polarity in the shared path
Data Source
AI summary
Systems and methods for providing controlled AC arc welding processes. In arc welding power source embodiments, configurations of main and auxiliary bridge circuits allow for the directional switching of the output welding current through the welding output circuit path and selectively provide one or more high impedance paths to rapidly decay the arc current. The high impedance path aids in the low spatter transfer of molten metal balls from a consumable electrode to a workpiece and further aids in the maintaining or the re-establishing of an arc between the consumable electrode and the workpiece when a molten metal ball is transferred.