An Investigation of the Interleaved Operation of a Stacked AC-DC Single-Stage Flyback Converter

Abstract

Low power AC-DC power conversion is typically done with a two-stage converter that consists of an AC-DC front-end boost converter that also performs input power factor correction and an isolated DC-DC back-end converter that is either a flyback or a forward converter. In applications where cost is an overriding factor, single-stage AC-DC converters that use a single power converter to simultaneously perform input power factor correction and AC-DC conversion can be used. In applications where output filtering and hold-up time are important considerations, single-stage AC-DC converters are implemented with a DC bus capacitor. The main objective of this thesis is to investigate the interleaved operation of a single-stage stacked AC-DC flyback converter that has less cost, size, and component stress than interleaved two-stage converters and interleaved non-stacked single-stage AC-DC converters. In this thesis, the steady-state operation of a stacked converter with interleaving is explained and analyzed in detail by using a computer program that is based on the principle of energy equilibrium. The results of the analysis, which are a set of equations related to key component stresses and losses and a set of graphs of steady-state characteristic curves is then used to select component values using an iterative design procedure. The performance of the stacked converter with interleaving is confirmed with results obtained by PSIM simulation as is the accuracy of the analysis. The thesis concludes with a summary of the thesis contents, conclusions, contributions, and suggestions for future work