Analytical modeling of inter-turn short circuit for multiphase fault-tolerant PM machines with fractional-slot concentrated windings

Inter-turn short-circuit faults that occur inside stator coils are difficult to cope with compared to terminal short-circuit faults. A general analytical model for inter-turn short-circuit faults is developed that employs a novel T-type equivalent circuit. When this model is used to investigate the impact of inter-turn short-circuit faults in PM machines with fractional-slot concentrated windings (FSCW), the model delivers fault response predictions that agree very well with results from finite element (FE) analysis. The model is used to show that the 24-slot/14-pole FSCW PM machine is vulnerable to very high inter-turn fault currents even when the remaining turns are shorted, offsetting its advantage of low magnetic coupling between phases.