A Sensorless Control for Five-Phase PMSMs Based on a Hybrid-Speed Estimator, Operating under Both Healthy and Single-Phase Open-Fault Conditions

The five-phase permanent magnet synchronous motor (5Ph-PMSM) exhibits a phase redundancy property, making it a promising candidate for electrified transportation. To enhance the reliability of 5Ph-PMSM drives, this study presents a simple sensorless control method that is filter-free, less dependent on parameters, and effective under both healthy and single-phase open-fault conditions. Central to this methodology is a hybrid-speed estimator, capable of estimating both rotor speed and the electromagnetic constant (which is also a speed quantity), meanwhile relying only upon the phase resistance and rotor flux. Specifically, a natural fault-tolerant control (FTC) strategy is implemented, utilizing the healthy mode Clarke and Park matrices continuously. Combined with a neutral voltage compensation method, this approach enables the sensorless control to effectively accommodate the single-phase open-circuit condition. The effectiveness of the proposed method is experimentally confirmed, demonstrating its resilience and universality in both healthy and single-phase fault conditions.