Autoconnected transformer-based 18-pulse ac–dc converter for power quality improvement in switched mode power supplies

Abstract

Switched mode power supplies (SMPS) are commonly used in telecommunication towers and welding equipments. In medium capacity SMPS, power quality at the utility interface is a major concern. A new autoconnected transformer is presented for power quality improvement in 18-pulse ac–dc converter fed SMPS with least magnetic rating. Various autoconnected transformers are studied for 18-pulse ac–dc rectification and a new autoconnected transformer is selected to improve the power quality of the supply current. The effect of load variation on SMPS is studied to demonstrate the performance and effectiveness of the proposed 18-pulse ac–dc converter-based SMPS in the wide operating range of the power supply system. A set of power quality indices at input ac mains and magnetic rating of various autoconnected transformers are presented to compare their performance. Laboratory prototype of the proposed autoconnected transformer-based 18-pulse ac–dc converter is developed and test results are presented to validate the proposed design and developed model of the converter system.