A Comparative Study of Two Buck-Type Three-Phase Single-Stage AC–DC Full-Bridge Converters

Almost all previously proposed single-stage, three-phase ac-dc converters are based on the boost converter, and the strengths and weaknesses of boost-based single-stage converters are well known. This is not the case for buck-based single-stage converters as little, if any, comparable research has been performed on these converters. The authors have previously investigated a three-phase ac-dc, single-stage buck-type converter that can simultaneously perform power factor correction and dc-dc conversion using the standard phase-shift pulse-width modulation technique for dc-dc full-bridge converters. This paper is a continuation of that work as its main focus is a comparison of the performance and characteristics of this converter with those of a modified version of the same converter. In this paper, the fundamental principles of both the converters are explained, the modes of operation of the modified converter are explained in detail and a procedure for the design of this converter is demonstrated with an example. Experimental results obtained from a prototype of the modified converter are presented and based on these results; the two converters are compared in terms of parameters such as input power factor and efficiency.