Eighteen-pulse AC-DC converter for harmonic mitigation in vector controlled induction motor drives

Abstract

This paper presents a novel autotransformer based eighteen-pulse ac-dc converter with reduced kVA rating, feeding vector controlled induction motor drives (VCIMD's) for power quality improvement at the point of common coupling (PCC). The proposed 18-pulse ac-dc converter is suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is being used. The proposed harmonic mitigator eliminates 5th, 7th, 11thand 13thharmonic currents, thereby improving the power quality at ac mains. A set of different power quality parameters for a VCIMD fed from the proposed 18-pulse ac-dc converter are computed to observe its performance. The effect of load variation on VCIMD is also studied to observe the effectiveness of the proposed harmonic mitigator. The simulated results are verified on the prototype autotransformer designed and developed in the laboratory. A comparative performance of different ac-dc converters based on eighteen-pulse rectification have also been presented to demonstrate the performance of the proposed AC-DC converter feeding VCIMD.