Analysis of New 18-Pulse Direct Symmetric Autotransformer Rectifiers with Dual AC-Voltage Feeding Capability

摘要

Ever increasing power quality requirements have impelled the development and usage of new front end ac-to-dc converters. Multi-pulse direct symmetric autotransformer rectifiers (DSAR) have arisen as a most advantageous passive solution, featuring high reliability and simplicity of operation, minimum kVA ratings, solid multi-pulse operation insensitive to impedance path mismatch or voltage distortion, reduced common-mode voltage, and reduced size and weight—hence the interest for mobile transport applications. This paper proposes three new DSAR topologies with the capability to operate from 0.5 pu and 1 pu voltage sources while generating 1 pu output dc voltage, thus significantly enhancing the operational flexibility of DSAR's. The paper presents a complete evaluation using Synopsys Saber to fully assess the thermo-electromagnetic capabilities of these new topologies, focusing on losses and efficiency, size and weight, and the overall power quality of these converters. Specifically, it measures harmonic current distortion, common-mode voltage and dc voltage ripple, all of this while operating under ideal and low power quality 0.5 pu and 1 pu ac voltage networks. Experimental prototypes are used to verify the operation of the proposed converters; a complete experimental evaluation will be included in the final paper.