Controlled ac drives in the case of ‘Sensor less control’ without mechanical sensors for speed have the attraction of high reliability. With the sensorless speed control technique the speed information is obtained without the use of speed or position sensors. However, the feedback information is still needed and is generated through indirect technique such as ‘estimation’. In this paper motor model in stationary reference frame is proposed and the speed estimation is done by using Model Reference Adaptive System (MRAS) based on voltages and currents that will give satisfactory operation in low speed region also. In this paper High Pass Filter (HPF) with feed forward control of stator flux is also used to get speed control at very low speeds and to avoid jerks generating at the time of transition from standstill to sensorless control. Simulation of sensorless control of induction motor using MRAS and HPF has been carried out by using Matlab/Simulink. The results have been presented and analyzed.
Sensor less control, Vector control, MRAS
