Direct torque control of four-switch three phase inverter fed induction motor using a modified SVM to compensate dc-link voltage imbalance

In this paper the direct torque control (DTC) of the induction motor fed by four switch three phase inverter (FSTPI) is investigated. A modified space vector modulation (SVM) approach with optimal voltage vector sequence is proposed to compensate the effect of DC-link voltage variations caused by circulating phase current through the capacitor bank. SVM-DTC scheme of FSTPI fed induction motor is based on stator flux oriented control. According to simulation results, this approach significantly reduces the effect of DC-link voltage variation on the output torque, flux and current waveforms.