Author : R.Shiju Kumar and T.Ruban Deva Prakash

Welding power supply is a device that supplies high current at low voltages in the range of 50V. Gas tungsten arc welding draws low current in the range of 5A. Gas tungsten arc welding machine operates with dc supply for steel welding and operates with 150Hz rectangular wave ac supply for aluminium welding to avoid oxidation and better welding quality. Welding power supply has constant current or constant voltage operation. This paper deals with constant voltage welding power supply. Conventional welding power supplies are transformer style or IC engine/motor driven generator style or inverter style devices. Harmonics, low power factor and transient disturbance are the major problems with conventional welding power supply. Recently, power electronic transformer gains importance due to reduced size and weight in many applications. Traditional power electronic transformer with its power quality analysis is presented in this paper. This paper also proposes a novel modular power electronic transformer based dc welding power supply for gas tungsten arc welding of steel. Modular topology based on dc-dc buck converter is used for the design. Also matrix converter power electronic transformer based ac welding power supply for gas tungsten arc welding of aluminium is proposed in this paper. DC link in input side is eliminated using 3-phase to 1-phase matrix converter. A simple control method for the matrix converter is explained in this paper. Performance is validated by simulation studies. It if found that the input voltage and current has some harmonics, but much less than that of traditional power electronic transformer topologies.

Keywords: Power quality, welding power supply, power electronic transformer, high frequency transformer, gas tungsten arc welding, steel and aluminium welding.

Article published in International Journal of Current  Engineering  and Technology, Vol.3,No.4(Oct- 2013)