Rotor-flux based MRAS speed estimator for direct torque and flux control of an induction motor drive

This paper presents a speed estimation scheme using Rotor flux based Model Reference Adaptive System (MRAS). This estimated speed is incorporated as a feedback to the Direct Torque and Flux Control (DTFC) of Induction Motor Drive (IMD). In this scheme the rotor flux linkage components of the Induction Motor (IM) are obtained from the Reference Model (RM) and Adaptive Model (AM) respectively. The difference between these quantities is called speed tuning error signal. The speed tuning error signal is passed through a PI controller to get the estimated speed. The estimated rotor speed is feedback into AM to reduce the error signal. The performance of the Rotor flux based MRAS is compared with the measured quantities of the IMD using MATLAB/SIMULINK software. The performance of IMD is simulated under various operating conditions, such as, no-load, load, change in speed and sinusoidal speed respectively.