Identifying Open-Circuit Fault Symmetries for Six-Phase Electric Machines

In this paper, all open-circuit fault cases of a six-phase machine are evaluated to identify fault symmetries and reduce the effective fault set. Recognizing these symmetries allows the development of optimal fault-specific control strategies because it substantially decreases the number of distinct cases that require analysis, tuning, and testing. The study performs a systematic classification for different fault combinations that yield identical torque harmonics by decoupling the multiphase system into alpha-beta components via the Clarke transformation. The results show that the use of the inherent symmetries in six-phase machines can greatly reduce the number of unique fault cases. This makes it possible to create a practical framework for designing robust and fault-tolerant drives.