Sensorless Speed Control Strategy for Brushless Doubly-Fed Reluctance Machines

The brushless doubly-fed reluctance machine (BDFRM) is a prospective low cost candidate for applications with limited variable speed requirements. The machine allows the use of a partially rated power electronic converter whilst its brushless design offers reliable and maintenance-free operation. This paper proposes a new observer based algorithm for speed and direct torque (and flux) control (DTC) of this machine without a shaft position sensor. The experimental results have demonstrated good controller performance down to zero applied frequency to the inverter-fed winding.