High-Efficient Portable Welding Machine Based on Full-Bridge Converter with ISOP-Connected Single Transformer and Active Snubber

This paper suggests a high-efficiency portable welding machine based on full-bridge converter with input-series-output-parallel (ISOP)-connected single transformer. Link voltage balance problem is theoretically analyzed according to deviations of transformer leakage inductances and transformer turns-ratios and simple voltage-balancing circuit using flying capacitor is introduced to remove this problem. Also, active-snubbing method is also proposed to improve overall efficiency by recovering parasitic resonant energy and regulating the voltage stress of rectifiers to the level that Schottky diodes are available. The feasibility of the proposed structure has been verified with 17.5-kW welding machine with 60-kHz switching frequency.