An 18-Pulse Uncontrolled Star Rectifier for Input Line Current Harmonic Reduction

Abstract

This article introduces a delta/fork transformer based 18-pulse uncontrolled star rectifier for large current and low voltage application. The proposed rectifier consists of two 9-pulse parallel connected uncontrolled star rectifier, delta/fork transformer and interphase transformer (IPT). Delta/fork transformer is designed and modeled optimally to produces two 9-phase supplies for two 9-pulse star rectifiers. The proposed rectifier enables to element lower than 17th order harmonics from the input line voltage and input line current. Total harmonic distortion (THD) of the input line voltage is less than 5% under wide load variation condition. The proposed rectifier suitable where isolation is required such as aluminum potline, traction substations, zinc electrolysis, graphitizing furnaces, copper refining and low voltage ac drives etc. Proposed rectifier is analyzed, designed, modeled and simulated in MATLAB software environment.