Speed Estimation of Sensorless Induction Motor through Vector Control Using MRAS and Direct Synthesis Test

The objective of this project is to develop a vector controlled induction motor drive operating without a speed or position sensor but having a dynamic performance comparable to a sensored vector drive. This thesis presents the control of an induction motor through sensorless vector control using MRAS and also with direct synthesis test. The theoretical basis of each algorithm is explained in detail and its performance is tested with simulations implemented in MATLAB/SIMULINK.Vector control of induction motor is based upon the field-oriented co-ordinates aligned in the direction of the rotor m.m.f. However, there is no direct means of measuring the rotor flux linkage position ρ and therefore an observer is needed to estimate ρ for the implementation of sensorless vector control. First the Dynamic model of induction machine was developed in the arbitrary reference frame. Second, with the help of synchronous reference frame model the indirect field oriented vector control was developed. Third, Model Reference Adaptive System is studied as a state estimator. Rotor flux estimation scheme is applied to MRAS to estimate rotor speed. . By using the Direct Synthesis test, we can estimate the speed directly without feedback and control algorithm. This test can reduce the total cost.