Sondeep Bassan

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.

Novel dual auxiliary circuits for ZVT-PWM converters

Novel active auxiliary circuits that allow the power switch in single-switch, pulse-width-modulated (PWM) converters to operate with zero-voltage switching (ZVS) are proposed in this paper. The main feature of these circuits is that the auxiliary switch can operate with a zero-current switching turn-on and turn-off without increasing the peak current stresses of the main switch. In this paper, the operation of active auxiliary circuits in general is reviewed, and a systematic method for synthesizing auxiliary circuits belonging to the new family is presented and demonstrated with several examples. Several new auxiliary circuits are presented, and the operation of one of the new circuits is briefly explained. A general set of guidelines for the design of auxiliary circuits belonging to the new family is presented. The feasibility of the new family of circuits is confirmed by experimental results obtained from a 500 W, 100 kHz zero-voltage-transition (ZVT)-PWM boost converter prototype implemented with an example auxiliary circuit.

Zero-current-switching techniques for buck-type AC-DC converters

Zero-current switching (ZCS) techniques are used to reduce the switching losses of the switches in three-phase power converters. In this paper, a number of ZCS techniques are considered for use in a three-phase single-switch buck-type ac-dc converter. This paper first reviews various ZCS techniques, then proposes a new ZCS three-phase single-switch quasi-resonant buck converter that can operate with input power factor correction. The operation of the proposed converter is discussed in the paper and its feasibility is confirmed with results obtained from an experimental prototype.

Properties and Applications of Quadratic Converters

The properties and applications of power electronic converters with voltage conversion ratios that are quadratically dependent on the duty ratio are discussed in this paper. A novel, soft-switched, three-phase, single-switch quadratic buck converter is also proposed. The converter is a zero-current- switching (ZCS) quasi-resonant type converter that can operate with significantly less switching frequency variation because of the quadratic nature of the converter. The operating principle of the proposed converter is explained, its operating modes along with key waveforms are shown and simulated results are presented in the paper.

A Three-Phase Single-Switch High Power Factor Buck-Type Converter Operating with Soft-Switching

This paper proposes a three-phase, single-switch, quasi-resonant, buck converter that can operate with input power factor correction. The converter can operate with a narrower switching frequency range and can therefore perform power factor correction over a wider range of line and load conditions than other converters of the same type. In the paper, the operation of the converter is discussed, a mathematical analysis of its steady-state characteristics is performed, and a design procedure is presented. The feasibility of the converter is confirmed with experimental results obtained from a prototype.

A three-phase reduced switch high power factor buck-type converter

This 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 this 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 voltage stress reduction technique for three-phase single-switch buck-type ac-dc converters

A three-phase single-switch ac-dc buck converter can operate with an excellent input power factor if the voltage across the three input ac-side capacitors is made to be discontinuous with zero voltage states. The main drawback to operating the converter in this Discontinuous Voltage Mode (DVM) that the peak voltage stress of the switch can be extremely high. A new variable switching frequency technique that will allow the converter to operate with reduced peak stress will therefore be introduced in the paper. In the paper, the new technique will be explained and its implementation in a standard buck and a quadratic buck converter will be analyzed. Comparisons between the new technique and conventional DVM will be made for both types of converters, and the analysis will be confirmed with results obtained from computer simulation.

Higher and Lower Power Single-Stage AC-DC Converters

In this paper, the properties of single-stage full-bridge converters are compared to those of single-stage forward converters. It is shown that, although both types of converters share similar properties, there are significant and surprising differences that have not been previously reported with respect to operating modes, DC bus voltage reduction techniques, and soft-switching. These differences are discussed in the paper, and conclusions about the properties of single-stage full-bridge converters are made based on results obtained from experimental prototypes

A New ZVT-PWM Converter with Reduced Circulating Current Losses

A new auxiliary circuit for single switch, zero-voltage-transition pulse width modulated (ZVT-PWM) converters is proposed in this paper. This circuit can assist the zero-voltage-switching (ZVS) operation of the main converter switch with lower auxiliary switch switching losses than many previously proposed ZVT-PWM converters, but with less circulating current than that found in ZVT-PWM converters with resonant type auxiliary circuits. The paper will review the operation of auxiliary circuits in ZVT-PWM converters and then discuss the properties and characteristics of the new circuit. Experimental results obtained from a prototype of a ZVT-PWM boost converter with the new auxiliary circuit are presented

A comparative study of three-phase single-switch buck converters

Three-phase single-switch buck converters can be made to operate with a very good power factor if their input capacitor voltages are discontinuous. Operating these converters in discontinuous voltage mode (DVM), however, results in high peak voltages that cause the switch to have peak voltage stresses. In this paper, a variable switching frequency control technique that can reduce these stresses is presented and a comparative study between the conventional three-phase single-switch buck and the quadratic buck converters operating with this technique is made.