Step down converter with hysteretic current control for welding applications

The present paper deals with a buck power converter used to control the current during a welding process. The voltaic arc is modeled by a variable resistance in series with a voltage source. The step-down DC-DC power converter is connected to the output of a conventional electromagnetic power source and a controls the energy flux to the welding process. An hysteretic current control scheme was implemented to guarantee a constant average current during the voltaic arc. The main power circuit is a buck converter that uses a high-power IGBT module as the main switch. The freewheel path is made up of three parallel diodes. The buck converter was designed for load currents of up to 200 A. A microcontrolled interface was developed to simplify the hardware configuration. A temperature sensor fitted on the IGBT heat sink has an indication of the temperature on the switch for monitoring purposes. The power converter´s characteristics are described. Simulations and experimental laboratory results are presented to show the performance of the structure