Position and velocity sensorless control for synchronous reluctance motor at low speeds and under loaded conditions using high-frequency extended EMF observer and heterodyne detection

Recently, synchronous reluctance motors (SynRMs) have attracted study because of their favorable properties, including limited thermal expansion of the shaft due to low heat generation by the rotor, the ability to drive at high velocity, a low degree of torque ripple and an absence of demagnetization problems. Sensorless control of SynRMs is now desired, and several methods have been proposed. These methods, however, have difficulties at low speed when the voltage signal necessary to estimate rotor position is very small. This paper proposes a new rotor position estimation method using both a high-frequency extended e.m.f.(EEMF) disturbance observer and a heterodyne detection. In this paper, it is shown, experimentally, that it is possible to control the SynRMs at low speeds and under loaded conditions without the position and velocity sensor using the new proposed method.