Fault-Tolerant Control of a High-Reliability Six-Phase Axial Flux Switching Permanent Magnet Machine

Abstract

In this study, a novel six-phase axial flux switching permanent magnet machine (AFFSSPM-TS) with a twisted structure is explored to enhance fault tolerance and overall system reliability. This design integrates the advantages of flux switching permanent magnet (FSPM) machines, such as high-power density and robust structural characteristics, while significantly improving fault resilience. The machine's electromagnetic behaviour and fault-tolerant capabilities are assessed through experimental validation. To ensure stable torque output under single-phase faults, an advanced control strategy is introduced, regulating the q-axis current and zero-sequence components within the synchronous reference frame. This approach effectively mitigates torque loss caused by phase disconnection while optimising copper losses. Furthermore, a weighted multi-objective optimisation framework, utilising a Genetic Algorithm (GA), is implemented to refine the fault-tolerant current references, maximising torque output and minimising energy dissipation under fault conditions. For short-circuit faults, a compensation strategy based on fault decomposition is developed, eliminating the need for complex real-time computations by directly compensating for faulty phase currents. Experimental results on a prototype machine confirm the proposed control strategy's effectiveness in maintaining torque performance and fault-handling capability.