ROTOR POSITION AND VELOCITY ESTIMATION FOR A SALIENT-POLE PERMANENT-MAGNET SYNCHRONOUS MACHINE AT STANDSTILL AND HIGH SPEEDS

This paper addresses self-sensing (''sensorless'') control of salient- pole permanent magnet synchronous motors (PMSM's). The major contribut ion of this work is the introduction of a simple-to-implement estimati on technique that operates over a wide speed range, including zero spe ed, The technique achieves simplicity by decoupling the, inherent cros s-coupling in PMSM's, The technique utilizes the dependence of inducta nce on rotor position in interior permanent magnet machines to produce position and velocity estimates both for held orientation and for all motion control of the drives. The technique functions in a manner sim ilar to a resolver and resolver-to-digital converter (RTDC) sensing sy stem, whereby in the proposed technique the motor acts as the electrom agnetic resolver and the power converter applies carrier-frequency vol tages to the stator which produce high-frequency currents that vary wi th position. The sensed currents are then processed with a heterodynin g technique that produces a signal that is approximately proportional to the difference between the actual rotor position and an estimated r otor position, This position error signal and a torque estimate are th en used as inputs to a Luenberger style observer to produce parameter insensitive, zero lag, position and velocity estimates.