Performance Improvements for MMA Welding Based on Self-Oscillating Inverter

摘要

This paper describes improvements developed in a Manual Metal Arc welding machine based on self-oscillating resonant inverter. A new standby operation sequence based on a double modulation phase is proposed in order to reduce the size of the discharge capacitor. This standby solution also relieves the resonant inductor voltage specification. The proposed converter operates with soft switching at no load and full load. There is no need to use a passive snubber in the converter. Power control of the developed Manual Metal Arc welding machine technique consists in controlling the magnetic saturation of a saturable transformer, by using a DC-control current circulating through an additional winding, in order to ensure a variable asymmetrical control as a function of the dc-control current. Therefore we can regulate the output current while maintaining the switching frequency close to the resonant one. Test results are presented to confirm the viability of the proposed arc welding power supply. The experimental results show that the proposed MMA welding power supply has promising feasibility in industrial applications.