Weld Circuit Calibration for Accurate Remote Arc Voltage Estimation
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Solution Overview
Problem
Accurate measurement of arc voltage in welding and plasma cutting systems is challenging due to fluctuations caused by resistance and inductance in the system, particularly when measuring remotely from the welding/cutting arc, leading to inaccuracies and increased system complexity.
Innovation Solution
A method for weld circuit calibration that determines the resistance and inductance values of the weld circuit and compensates for resistive and inductive voltage drops to provide an accurate estimate of arc voltage, using a power supply controller to filter and process current and voltage signals.
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 accuracy deteriorates due to resistance and inductance effects
Solution Approach 1:
The system performs preliminary calibration before normal operation to determine resistance and inductance values. During calibration, the contact tip is shorted to the workpiece and current pulses are applied to measure the relationship between voltage and current. This pre-determined electrical characteristic data is then used during normal welding to compensate for remote measurement errors, allowing accurate arc voltage estimation without direct measurement at the arc.
2Measurement precision
If additional sensors are added to measure arc voltage accurately, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system uses its existing power supply components and measurement capabilities to perform self-calibration and self-compensation. The power supply controller utilizes the same voltage and current sensing circuitry already present in the system, applying calibration currents and measuring the resulting voltage drops to determine electrical characteristics. This self-service approach eliminates the need for additional dedicated sensors or measurement equipment.
Solution Approach 2:
The power supply controller performs multiple functions: it generates welding current pulses, measures voltage drops during calibration, determines electrical characteristics (resistance and inductance), and compensates for measurement errors during normal operation. This multi-functionality allows a single controller to handle both calibration and welding control without requiring separate dedicated hardware for each function.
3Measurement precision
If inductive effects are compensated for, then measurement accuracy is improved, but device complexity increases due to additional compensation mechanisms
Solution Approach 1:
The system implements feedback by continuously monitoring the relationship between current and voltage during calibration and normal operation. The power supply controller uses the measured voltage and current values to calculate inductive voltage drops and compensate for them in real-time. This feedback mechanism allows the system to adapt to changing electrical characteristics and maintain measurement accuracy without complex hardware modifications.
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 an accurate estimation of arc voltage, reducing system complexity and cost by eliminating the need for additional sensors and improving measurement accuracy.
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
sampling a voltage pulse associated with the current pulse to produce voltage values that differ from the arc voltage due to an electrical circuit parameter of the weld circuit
Implementation Method 3
voltage values that differ from the arc voltage due to an electrical circuit parameter of the weld circuit
Data Source
AI summary
A method is performed in a welding or cutting system including 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. The method includes: while the contact tip is shorted to the workpiece to set an arc voltage equal to zero: sampling a current pulse to produce current values; and at a voltage sense point, on the power supply or the weld circuit, that is spaced-apart from the welding torch, sampling a voltage pulse associated with the current pulse to produce voltage values that differ from the arc voltage due to an electrical circuit parameter of the weld circuit; and computing a value of the electrical circuit parameter based on the current values, the voltage values, and the arc voltage equal to zero.