Effect of Zero-Vector Placement in a Dual-Inverter Fed Open-End Winding Induction Motor Drive With Alternate Sub-Hexagonal Center PWM Switching Scheme

Three-level inversion can be achieved by the cascade connection of two two-level inverters to an open-end winding induction motor. Several space vector based pulsewidth modulation (PWM) control strategies have been proposed for this power circuit configuration in the past. It is known that space vector modulation offers a degree of freedom in its implementation with regard to the distribution of the zero-vector. In this paper, the effect of placement of zero-vector for the implementation of space vector based PWM techniques for a dual-inverter fed open-end winding induction motor drive is reported. Apart from constructing a consistent theoretical frame work, experimental results with continuous and discontinuous PWM are presented in this paper and all the cases are compared.