Simple Carrier Based AZSPWM Algorithms for Vector Controlled Induction Motor Drive for Reduced Common Mode Voltage

Abstract

Few simple carrier approach based Active Zero State Pulse Width Modulation (AZSPWM) algorithms are presented for vector controlled induction motor drives for reduced common mode voltage variations. Though, the classical space vector PWM (SVPWM) algorithm gives superior waveform quality, it gives large common mode voltage variations and the complexity involved is more. To overcome these drawbacks, a simple scalar (carrier comparison) approach has been presented in this paper. In the proposed approach, the modulating signals of the AZSPWM algorithms are derived in a simple form. By adding the suitable zero sequence signals to the instantaneous phase voltages, the modulating signals are derived. Then, by using two carrier signals, and by comparing the modulating signals and carrier waves the pulses are derived for the inverter devices. As the AZSPWM algorithms did not use the zero voltage vectors, the common mode voltage variations can be reduced from ±Vdc/2 to ±Vdc/6 when compared with the SVPWM algorithm. To show the effectiveness of the proposed AZSPWM techniques, the simulation studies have been carried out on vector controlled induction motor drive and results are presented and compared. The simulation results show the usefulness of the proposed AZSPWM algorithms.