Improvements in designing the main circuit of arc welding inverter and the experimental verification

A novel main circuit for arc welding inverter has been proposed, in which the switching frequency is no longer restricted by the electrolytic capacitor, so it enables the DSP-controlled inverter welding machine to exploit the perfect control ability on the welding procedure and to satisfy all kinds of requirements for physical properties, out-characteristics and dynamic characteristics of electric arc. The proposed main circuit can remove soft-start circuit, reduce the capacitance of the capacitors, thus the volume and the cost of the system is further reduced. The adoption of EMI filter in the proposed circuit can suppress the conducted interference. A series of comparative analysis and experiments have been carried out, and the results indicate that the proposed circuit has many other improvements in increasing the power factor and efficiency, restraining inrush current and the harmonic distortion. This study conforms to development trend of ldquohigh frequency and green welding machinerdquo, and provides the potential for the further improvement of the dynamic performance of welding machine.