Single-Phase Open-Circuit Fault-Tolerant Direct Torque Control for Dual Three-Phase PMSM Based on SVPWM

High reliability is one of the primary advantages of the dual three-phase permanent magnet synchronous motor (DTP-PMSM). However, single-phase open-circuit fault in the DTP-PMSM drive suffers from large current harmonics and significant torque ripple. To solve these problems, a fault-tolerant direct torque control (FT-DTC) strategy based on space vector pulse width modulation (SVPWM) is proposed in this paper. Firstly, the component of stator flux on β-axis is modified under postfault. Based on this modified stator flux on β-axis, the stator current and the stator flux maintain the same circular trajectory both pre- and postfault. Secondly, the reference voltage is derived based on the relationship between the stator flux and the stator voltage. Then, the closed-loop controller on z-axis is introduced to suppress current harmonics caused by factors such as dead-time and back electromotive force (EMF) distortion. The output of the closed-loop controller is the harmonic voltage. Furthermore, a novel SVPWM technique is designed to modulate the reference voltage and harmonic voltage. Finally, experimental results demonstrate that the proposed FT-DTC strategy based on SVPWM can achieve high-performance operation under singlephase open-circuit fault.