Selective Torque Harmonic Elimination for Dual Three-Phase PMSMs Based on PWM Carrier Phase Shift

Recently, dual three-phase drives have attracted an increasing attention with their high torque density, improved fault tolerance, and direct use of the off-the-shelf three-phase inverters. This article presents a carrier-based algorithm for the selective elimination of high-frequency pulsewidth modulation (PWM) torque harmonics in dual three-phase drives. The PWM control of the power converters is one of the main sources of high-frequency torque ripple in high-power electrical machines. The proposed technique selectively eliminates the torque-ripple harmonic components by applying a proper carrier phase shift between the two three-phase subsystems of the dual three-phase drive, considering the arbitrary phase displacements among the two subwindings. Two case studies of dual three-phase machines with phase displacements of 0 and pi/6 are, respectively, analyzed under the most significant carrier phase-shift solutions. The torque performance improvement and the effect on the current ripple introduced by the proposed carrier phase-shifts are presented and validated by means of numerical, finite-element, and experimental results.