Welding Power Source Restriking Circuit Charging Control
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Solution Overview
Problem
In AC arc welding, charging of the restriking voltage often is not completed by the time of the next discharge, leading to potential arc interruptions, especially when the charging speed is slow or the output current is small.
Innovation Solution
The control circuit starts charging the restriking voltage during the opposite polarity period and ends charging after switching to the positive polarity, thereby extending the charging time and ensuring completion before the next discharge. Additionally, charging can begin after a predetermined time has elapsed or when the output current meets specific criteria, and may resume based on voltage or current conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charging of the restriking voltage is performed only during the positive polarity period, then the charging time is limited, but charging completion becomes unreliable especially when charging speed is slow or output current is small
Solution Approach 1:
The charging of the restriking voltage is started in advance during the opposite polarity period, before the positive polarity period begins. This preliminary action ensures that charging is well underway before the arc needs to be restriken, providing a buffer that ensures charging completion even when charging speed is slow or output current is small.
Solution Approach 2:
The charging action is extended to continue across the polarity transition, being started during the opposite polarity period and continuing through the positive polarity period. This continuous charging approach eliminates the gap that would otherwise exist between polarity periods, ensuring uninterrupted charging accumulation.
2Reliability
If the charging time is extended to ensure charging completion, then charging reliability improves, but the timing control becomes more complex
Solution Approach 1:
The control circuit monitors the polarity state and uses this feedback to determine when to start and end charging. By detecting the polarity transitions and using this information to control the charging timing, the system achieves reliable charging completion through a relatively simple feedback-based control mechanism rather than complex predetermined timing sequences.
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 effectively suppresses instances of incomplete charging, ensuring sufficient restriking voltage is available, reducing arc interruptions, and allows for the use of lower-voltage components in the charging circuit, potentially reducing costs.
Implementation Method 1
a restriking circuit 6 that applies a restriking voltage when the output polarity of the welding power source apparatus 100 switches
Implementation Method 2
transforms the high frequency power with a transformer 3
Implementation Method 3
converts AC power that is input from a commercial power source D into direct current (DC) power with a rectifying and smoothing circuit 1
Implementation Method 4
converts the DC power into high frequency power with an inverter circuit 2
Implementation Method 5
In AC arc welding, arc interruption tends to occur when the output polarity switches
Data Source
Figure 1
Figure 2A~2B
Figure 3(a)~3(e)
AI summary
A power source (A1) applies an AC voltage between a welding torch (B) and a workpiece (W). The power source (A1) includes an inverter circuit (2) to switch between a positive polarity and an opposite polarity, a restriking circuit (6) to apply a restriking voltage to an output of the inverter circuit (2) when the positive polarity is switched to the opposite polarity, and a control circuit (8) to control the restriking circuit (6). The restriking circuit (6) includes a restriking capacitor (62) to be charged with the restriking voltage, a charging circuit (63) to charge the restriking capacitor (62) with the restriking voltage, and a discharging circuit (64) to discharge the restriking voltage in the restriking capacitor (62). The control circuit (8) causes the charging circuit (63) to start charging at a time of the opposite polarity, and to end charging after the opposite polarity is switched to the positive polarity.