- In this paper, a new strategy for interturn short-circuit fault detection and isolation in Permanent Magnet Synchronous Machines (PMSMs) is proposed. The strategy is based on the measurement of PMSM currents and voltages. The fault detection for any phase of the stator windings is performed from the analysis of a vector residual generated by a state observer. Furthermore, the rotor angular speed is estimated from the measured voltages avoiding the use of a position sensor. In order to avoid false alarms, the stator fault isolation is performed through the sequence decomposition of the vector residual by using the reference-frame theory. Simulation results and experimental tests demonstrate the correct detection and isolation of stator faults in the PMSM. © 2015 IEEE.