Weld Cable Impedance Measurement via Power-Line Communication
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Solution Overview
Problem
Welding systems face challenges in accurately measuring the impedance of weld cables, particularly in applications where the welding location is distant from the power source, leading to significant voltage drops and inefficiencies in power delivery.
Innovation Solution
The system includes a welding power supply with communication circuitry to command a switch closure in the weld circuit, generating a controlled voltage signal with limited current to calculate resistance and inductance, allowing for impedance measurement at any time, even when not welding, and using the measured impedance to adjust the weld voltage and power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If weld cables are used to transmit power over long distances, then the welding system can reach distant work locations, but voltage drop increases and power delivery efficiency decreases
Solution Approach 1:
The system measures the actual voltage at the wire feeder and feeds this information back to the power supply controller. The controller then adjusts the output voltage to compensate for cable voltage drop, ensuring the wire feeder receives the correct voltage regardless of cable length or impedance changes.
Solution Approach 2:
The system dynamically changes the power supply output voltage parameter based on measured cable impedance and voltage drop. By adjusting the output voltage parameter in real-time, the system compensates for energy loss in long cables without requiring physical cable replacement.
2Reliability
If separate control cables are used for communication, then control signals can be transmitted reliably, but system complexity and number of cables increase
Solution Approach 1:
The weld cable is designed to serve multiple functions: power transmission, voltage sensing, and communication. The same cable that carries welding current also carries sense wires for voltage measurement and communication signals, eliminating the need for separate control cables and reducing overall system complexity.
Solution Approach 2:
The system merges power transmission and communication functions into a single cable infrastructure. Control signals and voltage measurements are superimposed on the power cable conductors, combining multiple functions into one physical medium and simplifying the cable routing and connections.
3Measurement precision
If impedance measurement is performed during welding, then real-time compensation is possible, but measurement accuracy decreases due to arc interference
Solution Approach 1:
The system performs impedance measurement during a preheat phase or open-circuit condition before actual welding begins. This preliminary measurement captures accurate cable impedance data without arc interference, and the results are stored for use during the subsequent welding operation.
Solution Approach 2:
The system periodically remeasures cable impedance at intervals during welding operations, such as during pause periods or between welds. This periodic measurement approach maintains measurement accuracy by avoiding arc interference while still providing timely updates to the power supply controller.
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 enables precise measurement and compensation for weld cable impedance, improving power delivery efficiency and simplifying the welding system by eliminating the need for separate control cables, thus enhancing the overall performance and reliability of welding operations.
Implementation Method 1
outputting a first signal at a controlled voltage to the measurement circuit; and after the first communication, limiting a current of the first signal to a first threshold level
Implementation Method 2
The weld circuit voltages and the current may then be used with Ohm's law to calculate a resistance of the remaining portion of the weld circuit after the weld circuit is shunted
Implementation Method 3
The power supply may also determine an inductance of a portion of the weld circuit by sampling the current and sampling voltages at points in the weld circuit during a ramp up condition of the test signal
Data Source
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AI summary
Welding power supplies, wire feeders, and systems to measure a weld circuit resistance via communications over the weld circuit are disclosed. An example welding-type power supply includes: a power conversion circuitry configured to: convert input power to output a signal via a weld circuit; and convert the input power to output welding-type power via the weld circuit; a voltage monitor configured to measure a power supply output voltage of the signal; communications circuitry configured to receive, via the weld circuit, a communication of a second voltage measurement; and control circuitry configured to: determine a resistance and/or and inductance of a portion of the weld circuit based on the power supply output voltage measurement, the second voltage measurement, and a weld circuit current.