A Space Vector Based PWM Method Using Only the Instantaneous Amplitudes of Reference Phase Voltages for Three Level Inverters

This paper presents a space vector based PWM method for the 3-level inverter. The three level inverter space phasors are located in 19 locations forming 24 sectors. The instantaneous reference space phasor is generated by switching between the three vectors forming the sector in which the tip of the reference vector lies. The proposed PWM method does not require the sector identification and look up tables to select the appropriate vectors. The inverter leg switching times are directly obtained from the instantaneous reference phase voltage amplitudes and the inverter switching vectors are automatically generated. The inverter leg switching times and the appropriate vectors are obtained using an algorithm, which does not involve computations like square root or coordinate transformations. The proposed method is implemented on a 1hp induction motor drive and the experiment results are presented.