Transformer Flux Control in Welding Power Supplies
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Solution Overview
Problem
Conventional welding-type power supplies using transformers are prone to magnetic saturation, leading to system unusability when saturation occurs, and existing solutions typically stop operation rather than mitigating the issue.
Innovation Solution
The implementation of a switched mode power supply with a transformer, current detector, flux accumulator, and controller that controls duty cycles to reduce magnetic flux while maintaining output, using techniques like instantaneous flux limit, flux balancing, and flux centering to avoid saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transformers are used in welding power supplies, then the system is simple and reliable, but magnetic saturation occurs leading to system unusability
Solution Approach 1:
The flux accumulator continuously monitors and accumulates magnetic flux values before saturation occurs. The controller uses this accumulated flux information to predict and prevent saturation by adjusting duty cycles in advance, rather than waiting for saturation to occur and then shutting down the system.
Solution Approach 2:
The system implements a feedback mechanism where the accumulated flux information is fed back to the controller, which then adjusts the duty cycles of the switches. This closed-loop control prevents magnetic saturation by continuously adapting the operating parameters based on the actual flux conditions in the transformer.
2Reliability
If duty cycles are controlled to reduce magnetic flux, then saturation is avoided, but the control system complexity increases
Solution Approach 1:
The flux accumulator automatically performs the integration of voltage over time to calculate magnetic flux, and the controller automatically adjusts duty cycles based on this accumulated information. The system serves itself by using its own operational data (voltage and time) to generate the flux accumulation without requiring external sensors or complex measurement systems.
Solution Approach 2:
The system changes the operating parameter (duty cycle) based on the accumulated flux information. By dynamically adjusting the duty cycle parameter, the controller maintains magnetic flux within safe operating limits, preventing saturation while allowing the system to continue normal operation.
3Reliability
If the system stops operation when saturation occurs, then component damage is prevented, but productivity is reduced
Solution Approach 1:
Instead of a static on/off operation mode, the system dynamically adjusts the duty cycles of the switches based on real-time flux accumulation. This dynamic control allows the system to operate continuously at varying power levels, adapting to prevent saturation while maintaining productivity, rather than simply stopping when saturation is detected.
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 the power supply to continue operating and generating welding-type power even when transformer saturation occurs, preventing system shutdown and ensuring continuous welding processes.
Implementation Method 1
a transformer configured to transform an input voltage to a welding-type voltage
Implementation Method 2
a current detector configured to measure a current through the primary winding
Data Source
AI summary
Systems and methods to reduce magnetic flux in a switched mode power supply are disclosed. An example welding-type power supply includes a switched mode power supply, including a transformer configured to transform an input voltage to a welding-type voltage; switches configured to control a voltage applied to the primary winding of the transformer; a current detector configured to measure a current through the primary winding; a flux accumulator configured to determine a net flux in the transformer based on a number of volt-seconds applied to the primary winding of the transformer; and a controller configured to: control duty cycles of the switches based on the net flux; and set a value of the net flux in response to the current through the primary winding satisfying a current threshold.