Efficacious Zero Sequence Voltage Elimination in Space Vector Modulation by Sigma Delta Modulation

The growing popularity of electric-motor-driven systems emphasizes the need for proper motor maintenance and necessitates zero sequence voltage (ZSV) elimination in electrical machines and drives. A spread spectrum modulation scheme for eliminating ZSV utilizing the space vector pulse density modulation (SVPDM) approach is proposed in this article. In the presented five-level inverter scheme, when vectors that do not contribute ZSV are considered, a 30° tilted three-level space vector diagram with inner and outer layers is formed. Reference vector residing in the outer layer is mapped to the inner layer and is vector quantized in a space vector quantizer to generate inner layer switching vectors. Outer layer switching vectors are then realized by the process of reverse mapping. This article investigates the two-level SVPDM scheme and ZSV-eliminated two-level SVPDM scheme to prove that the effectiveness of ZSV elimination can be determined from the shape of the demodulated waveform. Better the ZSV elimination, better will be the resemblance of demodulated waveform to sinusoidal signal. The scheme is experimentally validated with a 2.2-kW five-level dual inverter-fed induction motor drive and is compared with the space vector pulsewidth modulation scheme. The results of comparison confirm the effectiveness of the proposed scheme.