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Three-level voltage space phasor can be obtained using a dual two-level voltage source inverter (VSI). Two zero sequence voltage elimination pulse width modulation (PWM) switching variants are proposed in this paper for complete elimination of zero sequence voltage (ZSV) in the dual-VSI scheme. Both the PWM variants are designed in such a way that only one inverter is switched at any instant of time; to ensure that switching power losses in the dual-VSI is limited to one inverter only at any instant of time. Analytical expressions for the dwell times of the dual-VSI are developed and presented that successfully forces the ZSV in the dual-VSI to zero; at all instants of time. As a result, both the PWMs facilitate the dual-VSI to be driven from a single DC power source only. The implementation of the proposed PWM algorithms is greatly simplified and involves just the use of instantaneous magnitudes of the reference space vector. The implementation of PWMs totally avoids the time consuming task of sector identification and do not use look up tables. The PWMs proposed in this paper are first analysed, simulated using MATLAB/SIMULINK and then verified experimentally to validate the proposed PWMs.

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This paper discusses two new pulse width modulation (PWM) switching methods for eliminating common mode voltage (CMV) in the dual two-level voltage source inverter (VSI). Both the PWM methods also ensures that the switching power loss is limited to one inverter only at all instants of time. Analytical expressions for switching times of the phase switching devices of the two inverters are developed to force the CMVs in a dual two level VSI configuration to zero which enables the dualinverter drive to be driven from a single DC power supply. The implementation of the proposed PWM algorithm depends only on the instantaneous magnitudes of the reference space vector on the stationary reference axes. The impementation totally avoids use of sector identification and also the use of look up tables.Index Terms-Dual-inverter, Three-level inverter, Open-end winding induction motor drive, Pulse width modulation, Common mode voltage.