Transient processes in welding inverters and their influence on the stability of welding current

Abstract

Inverter converters used for dc-arc electric welding have been manufactured by many foreign and domestic companies and showed good results for decades. Until recently, ac welding was carried out only at an industrial frequency of 50 Hz. Earlier, we suggested carrying out arc welding at an increased frequency within the range of 25–75 kHz, proving it to be efficient taking into account welding physical processes. Results of investigations of “slow” electrical processes in a high-frequency inverter for ac welding at different stages of the welding cycle are given in this article. In particular, the transition processes in the inverter are studied in detail taking into account a whole variety of factors. We conducted a complex of investigations concerning the study of the character and duration of the transient processes in an alternative sign welding inverter with increased frequency, as well as the level of influence of the transition coefficient and time constant of the inverter-control system on these processes. The influence of design and parasitic data of the scheme on the nature of the “fast” and “slow” transient processes and changes in the parameters of the electric arc (loading) and parameters of the actuating signals were assessed. All this allowed determining the effect on the stability of the welding current and, therefore, on the welding quality.