Power Quality Improvement in Multilevel Inverters using Open-end Winding Motor Scheme

This paper presents a power quality improvement scheme on a 3-level inverter using induction-motor drive with open stator. Open-end induction motor(OEIM) is obtained by opening the star connected primary winding and feeding from both ends using two separate voltage-source inverters. A main 3level inverter, obtained by linking two 2-level inverters in cascade supplies the OEIM from one end. The other end of OEIM is fed with a supplementary inverter which works a series active filter to compensate for harmonics produced by the main 3-level inverter. The main inverter is space-vector modulation (SVM) controlled and the supplementary 2-level inverter is controlled with an active filtering control technique to reducing the voltage harmonic distortions produced by the main inverter. As the harmonic distortions in the motor voltage and current waveforms are reduced, efficiency of the drive will be improved.