A 28-pulse AC-DC converter based SMPS for telecom power supply

Abstract

This paper presents a new 28-pulse ac-dc converter for enhancing the power quality at the point of common coupling, while feeding a medium capacity switched mode power supply (SMPS). It consists of two series connected 14-pulse ac-dc uncontrolled converters fed by seven phase-shifted ac voltages. The proposed converter is found capable of suppressing up to 27 harmonic currents in the ac mains. The power factor is also improved to near unity over a wide operating range of the SMPS. The design and analysis of the proposed ac-dc converter is carried-out in detail. A laboratory prototype of the autoconnected transformer based 28-pulse ac-dc converter is developed, and various tests have been conducted on it to validate the simulated performance of the proposed converter. Several experimental results are also included to show the effectiveness and robustness of the proposed converter.