Investigation and comparison of single phase power factor correction (PFC) bridgeless ac-dc converters

AC-DC power converter circuits, where alternating current and voltage are converted to direct current and voltage, are the type of converters that we use the most in everyday life. In general, the connections of these circuits to the network are made via full bridge diode rectifiers. Since the full bridge structure found in a single phase AC-DC power converters is made up solely of diodes, there is no external control or intervention during the mentioned rectification. Single phase full bridge AC-to-DC converter circuits do infact have very low power quality. The reason for this is that full bridge construction behaves like a non-linear load group on its own, and large quantities of harmonics at the input of the converter are generated. In addition, the applications requiring high power are exhibiting over heating problems on the full-bridge. In order to overcome these problems caused by full bridge construction and to perform a more efficient power conversion operation, active power factor correction circuits are used. The main purpose of these circuits is to approximate the power factor value to unity on the network side during the conversion process. DC-DC converter circuit is required right after the full bridge in order to perform this operation in active power factor correction circuits. In general, this DC-DC converter circuit exhibits voltage boosting capability. xvi Power factor correction in AC-DC converter circuits with single phase active power factor amplification is performed by switching the semiconductor switch in the DC-DC converter at high frequency. As this process is carried out, the input current reaches to the output passing through at least three semiconductor elements. Because of this situation, the conduction losses are increasing and the efficent productivity is hence dropping. In addition, since the full bridge structure is found at the entrance of these circuits, problems of excessive heating occur in high power applications. In this study, the concept of bridgeless topology has been handled, in order to solve the problems caused by full bridge construction in AC-DC converters. How the bridgeless construction used in AC-DC converters has been examined and it's effect on the conduction losses has been assessed. Performance and usability of the bridge-free boost type AC-DC converter circuits are analyzed and compared according to the determined parameters stated in the the respective literature. Keywords: Full-bridge, active power factor correction, bridgeless converters, conduction loss