A new space vector modulation scheme for any N-level voltage source inverter which directly quantizes the reference space vector

A new space vector-based sigma-delta modulation scheme for any general N-level voltage source inverter which directly quantizes the reference space vector is proposed. The proposed scheme uses sigma-delta modulation with a quantizer implemented by the principle of space-vector quantization. A new scheme is proposed for directly quantizing the reference space vector to the multi-level inverter switching vectors without mapping it into 2-level inverter vector space. The property of integer values of the inverter switching vectors in 600 coordinates is utilized for the direct vector quantization of the instantaneous reference voltage space vector. The multi-level inverter vector space is divided into different parallelogram to define Voronoi regions around the inverter switching vectors in the proposed space-vector quantizer. The proposed scheme is implemented for a 5-level inverter realized by an open-end-winding induction motor fed with two 3-level inverters from either side having symmetrical DC link voltages, and results are presented.