Multipulse improved-power-quality AC–DC convertors for vector-controlled induction-motor drives

The paper deals with polygon autotransformer-based 12-pulse and 18-pulse AC–DC convertors feeding vector-controlled induction-motor drives (VCIMDs) for improving power quality at the point of common coupling (PCC). The design of autotransformers is carried out for proposed AC–DC convertors to make them suitable for retrofit applications, where at present a six-pulse diode bridge is used. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of proposed AC–DC convertors over a wide operating range. Laboratory prototypes of proposed autotransformer-based 12-pulse and 18-pulse AC–DC convertors are developed and test results are presented to validate the proposed design and model developed of the system.