A novel approach to sensorless control of induction motors

In this paper, sensorless control of induction motor is studied by reducing the adverse effect caused by the variation of the rotor time constant, which is the most effective parameter. For this purpose, a new robust observer for the parameter variation, is designed with the combination of sliding mode approach and Luenberger observer. Then, the observer is used in the rotor flux oriented vector control of induction motor. The control hardware is realized by using a motion control card on a computer. The current and the voltage values of the motor are transferred to the control algorithm software by means of the analog-to-digital converter on the motion control card. The actual speed of the motor is measured through the encoder and it is compared with it´s estimated value. Experimental results have shown that the estimated speed successfully converged to measured one. Simulation studies are performed in MATLAB, before implementing the proposed observer with rotor flux oriented control for the induction machine. The observer constants and the control parameters are tuned based on this simulation results. The comparative results and related overall conclusions are presented accordingly.