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.
