A novel sensorless control strategy of doubly-fed induction machines

Available sensorless speed control strategy of doubly-fed induction machines uses the rotor flux to estimate the rotor position and speed. It fails around the synchronous speed due to the numerical errors of integration operation required by the rotor flux calculation. A novel control strategy is proposed in this paper. It uses the stator excitation current to estimate the rotor position and speed. This strategy works properly in the whole speed zone. The principle of speed and position estimation is explained and the corresponding speed regulation system is built. In addition to the speed control, this system allows adjusting stator power factor. The proposed control strategy is examined in Simulink. The simulation results demonstrate the feasibility of the stator excitation current based rotor position and speed estimation as well as the control behaviors of the speed regulation system