A novel sensorless control strategy of doubly fed induction motor and its examination with the physical modeling of machines

Available sensorless speed control strategy of doubly fed induction machines based on rotor flux linkage fails around the synchronous speed due to the inaccurate estimation of the rotor flux linkage. In order to solve this problem, an excitation-current-based speed/position estimation strategy is proposed. The corresponding speed regulation system is constructed. Using the nonlinear transient finite element solutions of the doubly fed induction machine, a physical phase variable motor model is developed. The speed regulation system is verified using the proposed machine model. Simulation results show that the novel sensorless speed control strategy works properly in the whole speed zone and provides good speed regulation performance.