Autotransformer Based Nine-Phase AC-DC Converter for Harmonic Mitigation in Induction Motor drives

This paper deals with an autotransformer based improved power quality nine-phase ac-dc converter feeding vector controlled induction motor drives (VCIMD's). The design of the proposed autotransformer is presented alongwith the necessary modifications required for making it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed ac-dc converter is found capable of improving the power quality indices in a wide operating range of the drive. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed ac-dc converter. A set of power quality indices on input ac mains and on dc bus for a VCIMD fed from various ac-dc converters are presented to compare their performance.