CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF STUDY
Welding is a means of heating metal parts using electricity or flame so they melt and stick together. It can simply be defined as the joining process of two or more metal parts to act as a single piece. This is often done by melting the workpieces and adding a filler material to form a melt bath which cools to become a solid joint. Because of its strength, welding is used to join beams when constructing buildings, bridges and other structures. Welding can also be used to join pipes in pipelines, power plants, on construction sites and in home appliances. In addition, welding is used in shipbuilding, automobile manufacturing and repair, aerospace applications. There are many types of welding including arc welding, resistance welding, gas welding, among others. The focus will be on the arc welding because it is the most common type of welding and the main objective of this project. Arc welding is the welding process that uses an electrical discharge (arc) to assemble similar materials. The equipment which performs the welding operation under the supervision and control of a welding operator is known as a welding apparatus. To solve the problem of weight and size of the welding machine by conventional arc, it is necessary to design an inverter. The inverter provides much higher frequency than 50Hz or 60Hz for the supply of transformer used in welding. So much smaller mass transformer is used to enable the handling of larger power output. The noise produced by welding the welding machine to the recurve bow is reduced by selecting the operating frequency during the hearing of human capacity. The choice of 20Khz for the type of inverter welding machine arc was determined to meet the expectations above. The welding output current is controlled by controlling the high-frequency power transformer. This power is supplied by a frequency converter. Power switch IGBT (Insulated Gate Bipolar Transistor) or MOSFET is used for the design of the inverter because of its high switching. The use of the control circuit for controlling the welding output current is designed to control the high frequency power switch. Power switch Insulated Gate Bipolar Transistor is more efficient and less prone to MOSFET power switch failure.
1.2 AIMS AND OBJECTIVES OF THE PROJECT
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