A Novel Variable Impedance Design Concept of PM Fault Tolerant Machine

A novel variable impedance fault tolerant design concept is proposed in this paper for high reliable PM machines. The special fault tolerant ring structure realizes the automatic transformation of the machine from low impedance in healthy operation to ultra-high impedance in fault operation, which effectively suppresses the short-circuit current. First, the design guidelines for fault tolerant ring and the fault tolerance mechanism of variable impedance are introduced. Subsequently, two variable impedance machine topologies with separated and integrated fault tolerant rings are investigated. Finally, the prototypes are fabricated and the experimental results show that the proposed variable impedance topology has a turn-to-turn short-circuit current suppression capability that far exceeds that of the conventional fault tolerant topology.