Sensorless speed and direct torque control of doubly fed reluctance motors

The brushless doubly fed reluctance machine (BDFRM) is a potential low cost alternative to the existing solutions in applications with limited variable speed ranges. The cost effectiveness of the BDFRM drive can be attributed to the possibility of using a partially rated power electronic converter and reliable, maintenance-free operation afforded by the absence of brush gear. This paper proposes a load model based observer algorithm for speed and direct torque (and flux) control (DTC) of this machine without using a shaft position sensor. The preliminary results have demonstrated good controller performance over the desired speed range for different loading conditions.