A refined space vector modulation scheme for a six-level inverter system for dual-fed induction motor drive, using only the instantaneous sampled reference signals is presented in this paper. The dual-fed structure is realized by opening the neutral-point of the conventional squirrel cage induction motor. The six-level inversion is obtained by feeding the dual-fed induction motor with asymmetrical three-level inverter from one end and symmetrical three-level inverter from other end. The proposed space vector pulse width modulation technique does not require the sector information and look-up tables to select the appropriate switching vectors. The inverter leg switching times are directly obtained from the instantaneous sampled reference signal amplitudes and centers the switching times for the middle space vectors in a sampling time interval, as in the case of conventional space vector pulse width modulation.
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