Model reference adaptive system based sensorless vector control scheme for a 36‐pulse ac–dc converter fed 9‐level cascaded H‐bridge‐inverter driven induction motor drive

Abstract

A new modular transformer based 36‐pulse ac–dc converter for a cascaded H‐bridge‐inverter fed medium voltage induction motor drive is proposed in this work. The conventional multi‐pulse ac–dc converter has only 18‐pulses in its line input current with six output dc voltages, whereas, the proposed multi‐pulse ac–dc converter has 36‐pulses in its line current with six output voltages. Due to this, the proposed medium voltage induction motor drive has improved power quality at input end. A 9‐level cascaded H‐bridge‐inverter is applied on drive side to boost the performance of medium voltage induction motor drive. A modified model reference adaptive system based speed sensorless vector control is presented in this paper. A nearest level modulation scheme is used to operate a 9‐level inverter at fundamental frequency switching over the entire speed range of an induction motor drive. The performance of this drive is verified through both simulation and experimental results.