Torque ripple minimization of a five-phase induction motor under open-phase faults using symmetrical components

In order to minimize the torque ripple of five-phase induction motor under open-phase faults, the conventional strategy makes the stator current space vectors to move along the circular anticlockwise trajectories. However, the torque ripple is suppressed indirectly based on the coupling between spatial harmonic fields, and the analytical expression of the torque ripple is not considered. In this paper, according to the steady-state model using symmetrical components (SCs), the torque ripple is mainly caused by the first and fourth SCs. Hence, several possible current commands are deduced under single-phase fault and two-phase fault by suppressing the first and fourth SCs. Under single-phase fault, the proposed strategy shows better performance than the conventional strategy in terms of torque ripple, average torque and efficiency. Under adjacent two-phase fault, the proposed strategy shows lower torque ripple but a lower efficiency than the conventional strategy, and these two strategies can be selected according to the specific application requirements. Finally, the effectiveness of the proposed strategy is validated by the experimental results.