Design and Analysis of Universal Natural Fault-Tolerant SVPWM Strategy With Simplified Fault Diagnosis for Multiphase Motor Drives

Conventional space vector pulsewidth modulation (SVPWM) would degrade the operating performance of the multiphase motor drives under open-phase fault. To resolve this issue, existing solutions require the reconfiguration of transformation matrices. However, for the variable positions of faulty phases, the structure of matrices needs to be redefined, which is a restraint to the industrial implementation of such technologies. This study examined the offset of the voltage vectors after fault occurrence. Accordingly, a universal fault-tolerant SVPWM strategy is proposed for the purpose of natural fault tolerance, as well as a simplified fault detection scheme. Compared with conventional fault-tolerant SVPWM, it is highlighted with the characteristics of minimum reconfiguration, torque ripple-free operation, and applicability to handle various types of open-phase faults using a single-transformation matrix. Besides, the proposed strategy eliminates the redundant controllers and also reduces the degree of difficulty for fault diagnosis. Finally, the effectiveness of the proposed approach is evaluated experimentally with a seven-phase induction machine, which shows that the torque ripple could be reduced by about 40% in the presence of multiple faults compared with the conventional SVPWM strategy.