Fuzzy Luenberger Observer for Sensorless Control of Induction Motor Drive

The paper presents integration of fuzzy logic into adaptation mechanism of Luenberger observer for sensorless pulse width modulation-direct torque controlled (PWM-DTC) induction motor (IM) drive. At first, DTC strategy and PWM technique are described. Next, basic mathematical model for state representation, adaptive signal and proportional-integral (PI) adaptation mechanism of Luenberger observer is shown. However, the PI adaptation mechanism cannot ensure desired motor speed responses in both dynamic and steady-state operations of IM drive. Fuzzy logic control theory is added to overcome the disadvantage of PI adaptation mechanism via update proportional gain and integral constant time of PI controller. Simulations of sensorless control for two adaptation mechanisms are carried out at different reference speeds. Speed deviations are utilized to evaluate the performance of two adaptation mechanisms at both dynamic and steady-state operations. Theoretical assumptions of high performance of fuzzy logic are validated by assessments.