Pulse width-modulated switching strategy for the dynamic balancing of zero-sequence current for a dual-inverter fed open-end winding induction motor drive

Three-level inversion can be achieved with dual two-level inverters feeding an open-end winding induction motor. A space vector-based pulse width-modulated (PWM) switching scheme is proposed, which achieves three-level inversion using all the space vector locations with a single DC power supply. The zero-sequence current is reduced by reducing the zero-sequence voltage to zero, in the average sense, within a sampling time interval. The proposed PWM scheme balances the zero-sequence current dynamically, simply with a relocation of the effective time within a sampling time interval. The switching frequency of the inverters is also reduced to half as only one inverter is switched while the other is clamped in a sampling time interval. Also, the proposed PWM scheme employs only the three instantaneous phase reference voltages obviating the necessity of sector identification and lookup tables.