A PFC based power quality improved bridgeless converter for welding applications

Arc welding is performed using different technologies and most of them employ the welding power converter to form the arc. This paper presents a Power Factor Corrected (PFC), two stage bridgeless (BL) Single Ended Primary Inductance Converter (SEPIC) based switched mode power supply for arc welding applications. The front-end consists of a BL-SEPIC operating in Discontinuous Conduction Mode (DCM) to attain unity Power Factor (PF) at the AC mains while at the back end, a PWM isolated Full Bridge (FB) DC-DC converter is used to regulate the output DC voltage. Eliminating the input Diode Bridge Rectifier reduces the conduction losses and improves the thermal utilization of the BL converter´s switches. Individual controller is designed for the two stages. The proposed topology forms an arc welding power supply (AWPS) configured in constant voltage mode operation with over-current protection to improve the welding performance and weld bead quality. The performance of the AWPS system is evaluated to assess its power quality in terms of input PF (Power Factor), THD (Total Harmonic Distortion) of the AC mains current, voltage regulation and robustness.