Inter-turn fault modeling in IPMSMs for flux and fault index estimation, and torque compensation

This paper proposes a novel way to form the model for internal permanent magnet synchronous machines (IPMSM) under inter-turn short circuit (ISC) faults. Based on this model, an observer is formed for ISC diagnostics and torque compensation. The IPMSM model under ISC is presented as the model of a healthy machine, but with a disturbance given by the ratio between shorted and total turns times the current flowing in the failure path. The disturbance, defined as the fault index current (FIC), is estimated using an observer. The method is tested in Matlab/Simulink and corroborated with finite element analysis (FEA). The proposed technique provides the ability to identify the FIC for early ISC diagnostics. Furthermore, it also provides flux linkage estimation and torque performance compensation under ISC conditions.