In this application note, a power AC-DC converter suitable for use as the current supply for the MMA welding process is described. The MMA welding method is the most common method used for welding iron or steel. In recent years, the availability of low-cost and reliable solutions based on power electronics has shifted the approach to this application from a standard magnetic solution based on a low-frequency iron transformer to a high-frequency switching solution. This allows for compact and lightweight solutions at a relatively low price. The electronic control used in modern welding machines enables simple and safe use, so even an unskilled person can achieve good weld quality.
This document describes an AC-DC converter suitable for use as a current supply in Manual Metal Arc (MMA) welding processes. The MMA method is commonly used for welding iron or steel in small home repairs and light professional applications. The note explains how modern power electronics have shifted this application from traditional low-frequency transformers to high-frequency switching solutions, offering compact and cost-effective designs.
| Input Voltage (AC) | 185 Vac to 265 Vac |
|---|---|
| Output Peak Voltage | 80 V |
| Maximum Output Current | 135 A |
| Switching Frequency | 70 kHz |
| Efficiency | > 75 % |
| Power Rating | 2.5 kW |
The topology chosen is a double switch asymmetrical forward converter.
The duty cycle must not surpass 50% to ensure full demagnetization of the transformer.