A novel sensorless rotor position detection method based on field current pulsation for high power synchronous motors is proposed in this paper. Because of the reduced component count, this method can reduce hardware cost and improve system reliability. Position information is extracted from three-phase back electromotive force. An appropriate pulsation frequency is selected and a suitable control method is proposed. Finally, a series of experiment results are provided proving that proposed rotor position detecting method in this paper is correct and feasible.