Novel model of synchronous reluctance motors including magnetic saturation and its sensorless control

In this paper, we discuss a mathematical model that accounts for magnetic saturation in synchronous reluctance motors and we derive a novel mathematical model called extended EMF. In synchronous reluctance motors, since large currents cause magnetic saturation, it is necessary for a precise sensorless control to give it every consideration. We propose here the extended EMF model, which accounts for magnetic saturation, and we apply it to an estimation position method. We also discuss the d-axis directions of a motor model and determine an appropriate d-axis direction for the sensorless control. The experimental results verified that position estimations differ because of differences between the two d-axis directions. The results also demonstrate the success of the proposed sensor-less control based on the extended EMF model.