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

Abstract

The growing popularity of electric motor driven systems emphasize 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 zero sequence voltage, utilizing 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 zero sequence voltage are considered, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$30^{0}$</tex-math></inline-formula> tilted three-level space vector diagram with inner and outer layer is formed. Reference vector residing in outer layer is mapped to 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. The article investigates two-level SVPDM scheme and ZSV eliminated two-level SVPDM scheme, to prove that effectiveness of ZSV elimination can be determined from the shape of demodulated waveform. Better the ZSV elimination, better will be the resemblance of demodulated waveform to sinusoidal signal. The scheme is experimentally validated with 2.2 kW five-level dual inverter fed induction motor drive and is compared with space vector pulse width modulation (SVPWM) scheme. Results of comparison confirms the effectiveness of proposed scheme.