An Eight-level Inverter System for an Induction Motor with Open-end Windings

In this paper, an 8-level inverter system for an open-end winding induction motor drive is described. Multilevel inversion is achieved by feeding an open-end winding induction motor with an asymmetrical 3-level inverter from one end and a symmetric 3-level inverter from the other end. The combined inverter system with open-end winding induction motor produces voltage space phasor locations identical to an 8-level inverter. A total of 4096 space phasor combinations are available in the proposed scheme, distributed over 169 space vector locations. The proposed inverter drive scheme is capable of producing a multilevel PWM waveform for the phase voltage ranging from a 2-level waveform to an 8-level waveform depending on the depth of modulation