Three-phase push-pull modular converter based welding power supply with improved power quality

This paper deals with an efficient method of improving power quality for arc welding power supply. The analysis and design of modular three-phase ac-dc converter using three single-phase high frequency transformer based push-pull converter are carried out for welding power supply. A three-phase modular power-factor-correction (PFC) converter connected to a pulse width modulated (PWM) dc-dc converter ensures nearly unity power-factor of arc welding power supply and also suppresses input current harmonics. It includes the operation of a modular converter in discontinuous-conduction-mode (DCM) of operation with inherent power factor correction (DCM-PFC). This PFC converter exhibits ease of control, high frequency isolation as well as single stage power conversion. The fast dynamic response of this converter has a constant voltage mode in the range of welding currents and inherent parametrical short-circuit limit. This leads to improved arc stability and weld bead quality.