Welding Controller Calibration for Accurate Remote Arc Voltage
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Solution Overview
Problem
Accurate measurement of arc voltage in welding and cutting systems is challenging, especially when done remotely, due to resistance and inductance variations in the system, which fluctuate with current changes, particularly in pulsed waveforms, leading to inaccuracies.
Innovation Solution
A method involving calibration of the weld circuit to determine resistance and inductance values, and arc voltage compensation to account for resistive and inductive voltage drops, using digital filters to produce accurate estimates of arc voltage remotely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If arc voltage is measured remotely at the power supply, then measurement convenience is improved, but measurement precision deteriorates due to resistance and inductance variations
Solution Approach 1:
The system performs preliminary calibration before welding operations to establish baseline resistance and inductance values. The controller stores these calibrated values and uses them to compensate for voltage drops during actual welding, enabling accurate remote measurement without requiring sensors at the arc location.
Solution Approach 2:
The system continuously monitors welding current and uses feedback control to compensate for inductive effects. By measuring current changes and applying compensation algorithms based on stored calibration data, the system corrects for inductive voltage drops, maintaining measurement accuracy despite remote sensing location.
2Measurement precision
If inductance compensation is applied to improve arc voltage accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The controller acts as an intermediary that performs calculations to determine inductive effects. Instead of adding complex hardware compensation circuits, the system uses the controller to compute inductive voltage drops based on current measurements and stored inductance values, then applies software-based compensation to achieve accurate arc voltage determination.
Solution Approach 2:
The system replaces potential hardware-based inductance compensation circuits with software-based calculations and algorithms. The controller uses mathematical models and calibration data to compensate for inductive effects, eliminating the need for additional physical compensation components and reducing overall system complexity.
3Measurement precision
If calibration procedures are implemented to determine resistance and inductance values, then arc voltage measurement accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The system performs self-calibration by automatically determining its own electrical characteristics. During initial operation, the controller measures current and voltage to calculate the actual resistance and inductance values of the welding circuit, storing these values for future compensation. This eliminates the need for manual calibration procedures and external testing equipment.
Solution Approach 2:
The system performs preliminary calibration operations automatically during initial setup or before welding sequences. The controller executes calibration routines that measure circuit parameters and store compensation values, preparing the system for accurate measurements without requiring manual intervention or complex manufacturing processes.
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
Enables precise control of the welding process by providing accurate arc voltage measurements despite system variations, improving the accuracy and efficiency of welding and cutting operations.
Implementation Method 1
a power supply configured to deliver current pulses through a weld circuit to a contact tip extending from a welding torch to create an arc on a workpiece
Implementation Method 2
voltage values that differ from the arc voltage due to an electrical circuit parameter of the weld circuit
Implementation Method 3
Voltage variations caused by inductance can be particularly troublesome, because they fluctuate with changes in current
Data Source
AI summary
A method, performed in a welding or cutting system including a power supply configured to deliver a current to a welding torch to create an arc on a cut-off workpiece, comprises: sampling the current to produce digitized current values; filtering the digitized current values using a first digital filter to produce filtered digitized current values; sampling a voltage corresponding to the current to produce digitized voltage values; filtering the digitized voltage values using a second digital filter to produce filtered digitized voltage values; and controlling a current level of the current using the filtered digitized current values or the filtered digitized voltage values.