Dunisha Wijeratne

Quadratic Power Conversion for Power Electronics: Principles and Circuits

Quadratic converters have the voltage conversion ratios of two cascaded converters, but with fewer switches. They are not widely used, however, because they are generally less efficient than other converter types, but they can be useful for certain applications. In this paper, the characteristics of quadratic converters are explained, several examples of where they can be used in industrial applications are given, and a new three-phase converter that has been derived from quadratic conversion principles is presented. The feasibility of the new converter is confirmed with results obtained from an experimental prototype.

A Three-Phase Reduced-Switch High-Power-Factor Buck-Type Converter

The paper proposes a three-phase, reduced switch, buck-type converter that can operate with input power factor correction. The key feature of the proposed converter is that a switch in the converter has a lower peak voltage stress than a switch in a conventional three-phase, single-switch buck converter. The voltage stress in the proposed converter is limited to the peak value of the phase voltage of the input capacitors rather than the peak value of the line-to-line voltage, as is the case in the conventional converter. The reduction in the voltage stresses is therefore almost half as compared to that of conventional converter. This allows lower rated, standard devices to be used in the converters and reduces switching losses. In the paper, the steady state operation of the converter is presented and general properties and design considerations are discussed. The feasibility of the proposed converter is confirmed with results obtained from an experimental prototype.

A ZVS-PWM Full-Bridge Converter With Reduced Conduction Losses

A new soft-switching PWM full-bridge converter is proposed in this paper. The proposed converter has zero voltage switching (ZVS) in all its switches with fewer conduction losses than other ZVS-PWM full-bridge converters, due to a novel auxiliary circuit scheme. In the paper, the operation of the proposed converter is explained in detail, its features and design are discussed, and experimental results obtained from a lab prototype are presented.

A Three-Phase Single-Stage AC-DC Full Bridge Converter with High Power Factor and Phase-Shift PWM

Converters that integrate the functions of power factor correction (PFC) and isolated dc-dc conversion in a single power converter have been proposed to reduce the cost associated with operating two separate switch-mode converters. Many low power ac-dc single-stage converters have been proposed in the power electronics literature, but very few three-phase single-stage full-bridge converters and these require sophisticated methods of control to do both the PFC and the dc-dc conversion. A new three-phase ac-dc full-bridge converter that operates with standard phase-shift PWM is proposed in the paper. In the paper, the operation of the new converter is explained and analyzed, its design is discussed, and experimental results that confirm the feasibility of the converter are presented.

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.

A Three-Phase Single-Stage AC–DC PWM Buck-Type Full-Bridge Converter: Analysis, Design, and Characteristics

The main objective of this paper is to examine the operation of a fundamental buck-based three-phase single-stage ac-dc full-bridge converter. In this paper, the operation of this fundamental converter is explained and analyzed, and a procedure for the design of its key components is derived and demonstrated with an example. The performance and characteristics of the converter are shown with experimental results that have been obtained from a prototype, and general concluding remarks comparing buck-based and boost-based three-phase single-stage ac-dc full-bridge converters are made.

A Novel Three-Phase Buck–Boost AC–DC Converter

A simple, low-cost, reduced-switch, three-phase ac-dc buck-boost converter is proposed in this paper. The converter can operate with input power factor correction and is suitable for applications where a converter needs to operate over a wide range of input ac voltages and/or produce a wide range of output dc voltages. The paper will examine how a reduced switched converter with capacitive input filter operates in the boost mode and how a reduced switch converter operates in buck and boost modes. In this paper, the converters operation is explained and analyzed in detail and its design is discussed. The feasibility of the converter is confirmed by experimental results obtained from a prototype.

Three-phase single-stage AC-DC converters

In this paper, various three-phase ac-dc converters are reviewed and a new, simple, low-cost three-phase ac-dc single-stage PWM full-bridge converter is proposed. The operation of the proposed converter is explained and experimental results that confirm the feasibility of the converter are presented.

Analysis and design of a three-phase reduced switch buck-boost ac-dc converter

A simple, low-cost, reduced-switch, three-phase ac-dc buck-boost converter is proposed in this paper. The converter can operate with input power factor correction and is suitable for applications where a converter needs to operate over a wide range of input ac voltages and/or produce a wide range of output dc voltages. In the paper, the converters operation is explained and analyzed in detail and its design is discussed. The feasibility of the converter is confirmed by experimental results obtained from a prototype.

Analysis and design of a ZVS-PWM full-bridge converter with reduced conduction losses

A new soft-switching PWM full-bridge converter is proposed in this paper. The proposed converter has zero voltage switching (ZVS) in all its switches with fewer conduction losses than other ZVS-PWM full-bridge converters, due to a novel auxiliary circuit scheme. In the paper, the operation of the new converter is explained and analyzed, a design procedure is presented and demonstrated with an example, and experimental results that confirm the feasibility of the converter are presented.