Improved Power Quality Ac-dc Converter Research Articles

Analysis of Three Phase 3-Level NPC Voltage Source Converter for AC-DC Conversion

The use of power electronic converters influences the generation of harmonics and reactive power flow in power system. Therefore, three-phase multilevel improved power quality AC-DC converters are gaining lot of popularity in power conversion applications. This work deals with critical problem of multilevel structure i.e neutral point potential (NPP) variation. In this paper, a simplified current controlled scheme is presented to ensure unity power factor operation. Neutral point potential (NPP) of three-phase, 3-level NPC AC-DC converter is controlled by modifying control signal in the controller using NPP regulator. An auxiliary circuit is being presented in this paper as an alternative option for controlling the neutral point potential of the converter. Comparison has been carried out between these control techniques in terms of power quality. A complete mathematical model is presented for better understanding of both techniques used for NPP control. The presented control techniques has been verified through simulation investigations and validated

Discussion of “A Comparative Study Between PI and Type-II Compensators for H-Bridge PFC Converter”

Presents a discussion on the paper, “A review of single-phase improved power quality ACDC converters,” (Singh, B. et al), IEEE Trans. Ind. Electron., vol. 50, no. 5, pp. 962–981, Oct 2003.

Microprocessor based Symmetrical Multipulse Modulation in a Three-Phase Improved Power Quality AC-DC Converter with Four-Quadrant Switch Realizations

A three-phase a.c. controller using power MOSFETs operating in high- frequency chopping mode has been developed fabricated and tested with resistive load. The microprocessor based firing scheme is used to test the four-quadrant switch realizations. The output voltage is smoothly varied using symmetrical multipulse modulation by varying the duty cycle, and the relevant experimental results are furnished. The harmonic analysis of the chopped wave is made in terms of the number of pulses per cycle and pulse width. For same values of power factor and per unit output voltage, it can be concluded from the test results that the proposed scheme has much lower values of lower order harmonics as compared to conventional thyristor phase control. The computed results have been experimentally validated.

A Review of Three-Phase Improved Power Quality AC–DC Converters

Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.