Rotor position estimation for a sensorless PMSM using high-frequency signal injection method

The high-frequency signal injection method has been proved as a practical technique to estimate the rotor position for PMSM. However, it becomes an additional issue that deserves investigation to improve the detection accuracy. In this paper the detection technique based on fundamental high-frequency signal injection method is presented and its defects are analyzed. A special signal processing method is implemented to demodulate the signal which contains rotor position information. The improved approach with this demodulation technique, which can effectively inhibit the nonlinear distortion caused by inverter and the delay caused by filter, is proposed.