Power factor correction of three phase AC-DC converters

ABSTRACT In this theses, various three phase rectifier converters that are used for active shaping of the mains current are discussed. These converters are classified according to their power and voltage needs. In these discussions circuit topologies, operation principles, the diffrences from conventional methods, simulation and experimental results are explained. In the first chapter, three phase ac-dc converters which have high power factor are classified. Converters are basically separated to two parts, called unidirectional and bidirectional. Then each part is separated to five parts. These are boost, buck, boost-buck, multilevel and multipulse converters. The necessary general information about each converter is given in this chapter. In the second chapter, unidirectional three phase ac-dc converters which have high power factor are discussed. Power flow is just from ac supply to dc load so they are called unidirectional converters. In the third chapter, bidirecitonal three phase ac-dc converter which have high power factor are discussed. These converters have bidirectional power flow. First flow direction is from ac supply to dc load like unidirectional converters and second direction is from dc load to ac supply. The second flow direction is necessary for applications of motor. The last fourth chapter, the results, differences, advantages and disadvantages from conventional converters of each converter in the same category are explained. Keywords: Three phase ac-dc converter, power factor correction, unidirectional and bidirectional power flow, total harmonic distortion. xiv