An improved sensorless control algorithm for faulttolerant control was proposed for the dual winding FTPMM. The sensorless control algorithm, based on the back EMF method, utilized the flux linkage generated by each phase winding and the back electromotive force to estimate the position of rotor. The phaselocked loop technology was used to compensate for errors. The parameters used in this method were identified online, and the identification results were updated to the rotor position estimation algorithm. The rotor position and speed measurement could be achieved through the method in the case of doublewinding permanent magnet faulttolerant motor operating normally, singlephase fault or multi phase faults. The experiment was carried out by MATLAB/Simulink to verifiy the accuracy of the rotor position estimation method.