Performance analysis on parallel Connected cascaded power converter For arc welding system

Abstract

Welding is an integral process in automotive, construction, and other process industries. Among the several welding techniques available, arc welding is one of the widely used welding methods. Arc welding requires high current to join two metals, which has necessitated the need for power electronics based power source. newlineThe conventional welding power source comprises a three stage conversion employing a diode rectifier, high frequency inverter followed by high frequency rectifier. This power source suffers from high conversion loss and pollutes the grid by injecting harmonics to the grid. The intermittent nature of welding current in the welding process is the main reason for power quality issue. In view of the above aspect, this thesis explores the suitability of single stage parallel cascaded DC-DC converter topology for welding power source. The parallel configuration ensures proper current sharing to reduce the stress on semi conductor devices and cascaded topology ascertains steep step down in voltage. newlineThis thesis presents a detailed performance investigation of three cascaded converter topologies namely buck fed buck, buck fed SEPIC and buck fed cuk converter. The results reveal that the proposed parallel cascaded DC-DC converter topology produces the required voltage and current for the welding process. The buck fed cuk converter exhibits better static and dynamic characteristics in comparison with other topologies. newlineThe design of closed loop controller for buck fed cuk converter is detailed in this thesis with the objective of improving the dynamic characteristics. A hybrid controller combining the merits of PI and Fuzzy controller is proposed to regulate the output voltage of the converter newline