Modeling of Different Winding Configurations for Fault-Tolerant Permanent Magnet Machines to Restrain Interturn Short-Circuit Current

This paper describes an analytical model to evaluate the short-circuit (SC) current resulting from an interturn fault by computing the self and mutual inductances under SC fault condition. Two different concentrated winding configurations, i.e., horizontally and vertically placed conductors in the slot of a fault-tolerant permanent magnet synchronous machine are considered. By computing the associated slot-leakage and air-gap fluxes, the self inductance of both healthy and faulty windings as well as the mutual inductance between them, the SC current can be determined for any position and number of shorted turns. The proposed model is verified with finite-element analysis and validated experimentally. It will be shown that the magnitude of an interturn SC current depends on both the number of shorted turns and their position in the slot. The measured SC inductance shows that a new proposed concentrated vertical winding configuration can inherently limit the SC current and reduce its dependence on the position within the slot.