A Space Vector Modulation Scheme for a Dual Two Level inverter fed Open-End Winding Induction Motor Drive for the Elimination of Zero Sequence Currents

The dual two level inverter fed open-end winding induction motor drive gives voltage space phasor locations similar to a three-level inverter fed induction motor drive. The dual inverter scheme renders advantages such as redundancy of the space vector combinations for the same number of space vector locations and the absence of neutral point fluctuations. In a dual inverter scheme, a total of 64 space vector combinations are distributed over 19 space vector locations compared to 27 space vector combinations distributed over the same number of locations in a three level inverter. The common mode voltages (the harmonics of the triplen order) need to be suppressed by transformer isolation or by the use of harmonic filters. In this paper, a space vector modulation scheme for the suppression of zero sequence currents (the harmonics of the triplen order) for a dual two level inverter fed open-end winding induction motor drive is described. The proposed scheme does not require bulky transformers or harmonic filters for the elimination of the zero sequence currents. The proposed space vector PWM is based on the observation that certain voltage space vector combinations in the dual inverter scheme do not contribute to the triplen harmonics and hence the PWM scheme that exclusively employs these combinations is used to eliminate the triplen harmonic current