Torque dynamic performance enhancement of five-phase permanent magnet synchronous motor with open-circuit fault

Multiphase permanent magnet synchronous motors (PMSMs) have attracted much more attention for their high efficiency, low torque ripple and good fault tolerance. However, open-circuit fault results in asymmetrical motor behaviour, and deteriorates torque performance, especially dynamic response. This paper proposes a novel fault-tolerant direct torque and flux control (DTFC) strategy to restrain fluctuating torque and enhance torque dynamic performance of a five-phase PMSM with open-circuit fault. The novelty of the proposed strategy is the development of DTFC based on stator flux orientation under the open-circuit fault condition and the third harmonic current suppression with carrier-based pulse width modulation technology. Consequently, the decoupling control of torque and stator flux can be achieved under the open-circuit fault condition, and the third harmonic current can be restrained without additional control. Combined with deadbeat control, the heavy computation burden can be reduced. Thus, the proposed strategy not only can enhance torque dynamic performance under open-circuit fault operation, but also keep smooth torque with circular stator flux trajectory before and after open-circuit fault. The effectiveness of the proposed strategy is verified by the simulation and experimental results.