Sliding-mode and fuzzy logic control based MRAS speed estimators for sensorless direct torque and flux control of an induction motor drive

In this paper, a rotor-flux model reference adaptive system (MRAS) based speed sensorless direct torque and flux control (DTFC) of induction motor drive (IMD) using sliding-mode control (SMC) and fuzzy logic control (FLC) based adaptation mechanism schemes are implemented to replace the conventional constant gain PI-controller (PIC). The SMC is considered to minimize the error dynamics under different loading conditions, which is derived based on Lyapunov theorem. Furthermore, the FLC adaptation scheme is proposed to minimize the chattering phenomenon as well as achieve high performance speed sensorless drive with less error signal. The performance of each adaptation control schemes has been tested for its robustness to sudden change in speed and load disturbance. A detailed comparison of different control schemes are carried out in a MATALB/Simulink environment in both sensor and sensorless modes of operation, when a IMD is operating in forward and reversal motoring under no-load, load, sudden change in speed and sudden zero speed conditions.