Investigation of single phase switch mode sepic PFC rectifiers

Abstract

Single phase diode rectifiers are widely used in industrial, commercial, utility and domesticapplications.Manyinputwaveshapingmethodshavebeenproposedtosolvethep roblem ofpoorpowerfactorwhichcanbeclassifiedasactiveandpassivemethods.Five different configurations based on single phase SEPIC topologies have been proposed to solve the low efficiency, poor input power factor and total harmonic distortion problems of AC-DC converters. The proposed topologies show superior performance over output regulated conventional single phase AC-DC converters. The topologies proposed are input switched output-bridge configuration, input switched output- bridgeless configuration-1 and configuration-2, two switch output-bridge configuration and two switch output bridgeless configuration of single phase SEPIC AC-DC converter. The proposed configurations are designed separately for operating the converters as buck and boost converters. Results are compared with the results of conventional output switched single phase Boost rectifier, input switched Boost rectifier and output switched SEPIC rectifier. Proposed topologies show lower input current THD, higher power factor and high efficiency compared to the previously mentioned conventional rectifiers. Typical output voltage and input current waveforms are shown in the thesis work. It has been found that without feedback control input current THD is not in acceptable range. Therefore a feedback controller is designed in this thesis work which makes the power factor of the rectifier above 0.9 and keeps the input current THD less than almost 10%. The feedback controller with the power stage of the proposed topologies are also designed in such a way that gives regulated output voltage with load changes and input voltage variations as well. The results show that, the proposed configurations based on SEPIC topologies give better performance over all the conventional output switched and input switched boost rectifiers and also output switched SEPIC rectifier.