A New Space Vector Modulation Scheme for Multilevel Inverters Which Directly Vector Quantize the Reference Space Vector

A new space-vector-based sigma delta modulation scheme for any general N-level voltage source inverter is proposed in this paper, which directly quantizes the reference space vector. The proposed scheme uses the sigma delta modulation with the quantizer implemented by the proposed space vector quantizer. A new scheme is proposed for directly quantizing the reference space vector to the multilevel inverter switching vectors without mapping it into two-level inverter vector space. Voronoi regions of the multilevel inverter vector space in the proposed space vector quantizer are defined as a parallelogram with the inverter switching vectors as its vertices. The property of the integer values of the inverter switching vectors in 60° coordinates is utilized for the direct vector quantization of the instantaneous reference voltage space vector. The proposed scheme is implemented for five-level inverters realized by an open-end-winding induction motor fed with two three-level inverters from either side having symmetrical dc-link voltages, and results are presented.