Sensorless rotor position estimation through current signature analysis based on rotor saliency harmonic

This paper presents a new technique for estimating the rotor position from the stator current by evaluating rotor saliency harmonics due to rotor slotting effects. These harmonics arise independent of speed and any time-varying machine parameters. Therefore, the proposed technique can be used to estimate the actual rotation of the rotor versus the stator in the time domain using filters and a sophisticated down sampling technique. Since the rotor slot current harmonics are extracted from a line current, this is a strictly noninvasive technique. So far, this technique is applied, but not restricted, to line fed induction machines. Practical results of the proposed estimation technique are compared with the measured rotor position obtained from an encoder