Torque ripple reduction PWMs for a single DC source powered dual‐inverter fed open‐end winding induction motor drive

Abstract

Two new pulse width modulation (PWM) methods are proposed for a dual two-level inverter (DTLI) fed open-end winding induction motor drive for complete elimination of zero sequence voltage (ZSV), enabling the DTLI drive to be powered from a single DC power supply only. One of the PWM methods is carefully devised and uses a single inverter only to be switched at all instants of time and dwell times of that switching inverter are derived by applying a simple volt-second balance principle, for ZSV elimination. The second PWM method involves switching of both the inverters, for ZSV elimination in the DTLI. While the dwell times of first inverter are derived using the concept of ‘effective-time’, whereas dwell times of the second inverter are obtained by thoughtfully exploiting the notion of ‘phase-shift’. Additionally, torque ripple performance of the open-end winding induction motor is theoretically analysed; ripple content is quantified to compare the performance of the proposed PWM methods. Finally, a typical PWM variant that results in the least torque ripple in the induction motor is recommended. All the envisaged ZSV elimination PWM methods and its variants are simple to implement and are first analysed, simulated and experimentally verified.