Low speed sensorless variable structure control of induction motor

Torque and speed sensorless induction motor control is presented in this paper. The idea is realized using a sliding mode closed loop rotor flux observer for estimation of electromotive force of machine. This signal is then used in nonlinear stator flux and torque control of induction motor and in rotor flux observer for speed and flux estimation. The analysis of the proposed method is included. Proposed control scheme was implemented on DSP system extended with FPGA where PWM procedure with dead time compensation was realized. Experimental results demonstrated high efficiency of the proposed estimation and control method.