Influence of Leakage Inductance of a Transformer Operating in a DC Resistance Welding Machine on Welding Conditions

The paper is focused on analysis of properties of power electronic transformer operating at resistance welding machine with frequency of 10 kHz and its influence on commutation process in output rectifier. Recently, the most popular resistance welding systems in industrial processes are based on DC welding machines with power electronic inverters. Such systems has numerous advantages for resistance welding, but because of very high welding current, power electronic converters are very sensitive on leakage inductance of the transformer. So, the output transformer, having output current at a level of 10 kA or more, needs special design to minimize the leakage inductance. Analysis in the paper is based on existing resistance welding system and shows in qualitative and quantitative way influence of leakage inductance on the output current of the welding machine. Also some technological aspects are discussed.