Input switched high performance single phase AC-DC converters

Abstract

Single phase diode rectifiers are widely used in industrial, commercial, utility and domestic applications. Many input wave shaping methods have been proposed to solve the problem of poor power factor which can be classified as active and passive methods. Six different DC-DC converter topologies have been studied to solve the low efficiency, poor input power factor and total harmonic distortion problems of single phase AC-DC converters. The proposed topologies showed superior performance over passive filtering techniques and output regulated single phase AC-DC converters. Some of the input switched topologies have been reported earlier, whereas, new input switched topologies with reduced component number are proposed in this thesis. Five reduced component input switched single phase AC-DC rectifier has been studied. The topologies used are Boost configuration-2, Buck-Boost configuration-3, Ćuk configuration-2, SEPIC configuration-2 and Inverse SEPIC configuration-2. Results are compared with the reported ones. Proposed topologies show lower input current THD, higher PF compared to previously reported topologies. However efficiency remains almost the same for both previous and proposed topologies. All the newly reported topologies are easier to implement. Typical output voltage and input current waveforms are shown. It has been found that without feedback control, the input switched single phase rectifiers perform better than output regulated single phase AC-DC converters in terms of input current THD, input power factor and conversion efficiency. Input switched single phase AC-DC converters reported earlier and proposed in this thesis are expected to perform better with feedback control circuit as well. As an example an input switched Boost regulated single phase AC-DC converter is studied and its performance is briefly compared with output regulated Boost single phase AC-DC converter.