Design and Analysis of SEPIC-Based Single-Stage Three-Phase Inverter

This chapter presents a novel design of single-stage three-phase inverter based on SEPIC. The designed inverter has special features that are not seen in the traditional current source inverter (CSI) where DC current at input side is always more than AC current at output side or in the case of traditional voltage source inverter (VSI) where we have voltage at output side smaller than the DC voltage at input side. The presented inverter topology has inherent characteristics of both buck and boost converters. By varying the duty ratio, functioning of the converter can be controlled and thus provide flexibility to the inverter which can be used for both isolated and grid mode cases where desired AC voltage output is either smaller or more than the input voltage. Also, in the proposed inverter, the number of energy storage elements, viz. capacitors and inductors, is substantially reduced so as to improve reliability of the system along with reduction in its overall dimensions and thereby reducing the total cost involved. The proposed inverter is controlled by fuzzy logic by defining various implementation rules along with usage of various membership functions so as to get desired output from the inverter. The converter model along with inverter model, the fuzzy controller and results are presented in the present work in detail.