Pulse Doubling in 18-Pulse AC-DC Converters

In this paper, a novel 36-pulse AC-DC converter is designed, modeled and simulated using pulse multiplication in an 18-pulse AC-DC converter using DC ripple re-injection technique. The proposed technique is suitable for large current rating rectifiers such as electrowinning, electrochemical processes, induction heating, plasma torches, etc., where isolation is required mainly for stepping down the supply voltage. It consists of a parallel 18-pulse AC-DC converter configuration involving three phase shifted uncontrolled diode bridges and interphase reactors tapped with diodes. A set of interphase reactors is used which is capable of effectively doubling the pulse number in the converter. A prototype of 36-pulse converter is developed to validate the design and its model. It improves the power quality to meet IEEE-519 standard at varying loads.