Abstract:
Five-phase permanent-magnet synchronous motor (PMSM) with traditional direct torque control (DTC) has such problems as large harmonic currents, high common-mode voltage (CMV), large torque and flux linkage ripples, and unsmooth operation under open-circuit fault. To solve these problems, a natural fault-tolerant switching-table-based DTC strategy is proposed. According to the fundamental voltage vector distribution characteristics under pre- and post-fault conditions and the principle that synthetic voltage vectors are zero in the third subspace, virtual vectors (VVs) are built, and then the same set of natural fault-tolerant switching-tables for pre- and post-faults are designed. Therefore, not only the torque fluctuations caused by open-circuit fault can be restrained, but also the third harmonic currents and CMV can be suppressed, and the ripples of torque and flux can be reduced both under healthy and fault conditions. The feasibility of proposed strategy is verified by the experimental results.