Synchronous Motor Sensorless Drives based on Rotating Signal Injection and Direct Ellipse Estimation

The paper deals with a position sensorless control for synchronous motor drive with a reduced number of tunable parameters. The current response due to the high-frequency rotating signal injection describes an elliptical trajectory centered on the fundamental current vector and its major axis tilt is related to the rotor position. The proposed method fits the motor current response on the implicit ellipse equation by means of the least square (LS) algorithm. The proposed LS algorithm processes the measured currents, without the need to filter them as occurs in conventional injection methods. No motor parameters are required to tune the proposed position estimator. The method was validated throughout several experimental tests performed on a permanent magnet synchronous motor electric drive.