الفهرس 
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Abstract
Direct torque, and flux control (DTFC) of an induction motor fed by a voltage source inverter is the simplest control strategy that does not need long computation time, can be implemented without mechanical speed sensors and is not sensitive to motor parameter variations which means parameter identification process is not needed In principle, the motor terminal voltages and currents are sampled and used to estimate the motor flux linkage and electromagnetic torque. By virtue of observing the flux linkage vector position and the instantaneous errors in stator flux linkage, and torque magnitudes, a space voltage vector is selected to restrict the torque and the flux errors within their respective flux, and torque hysteresis bands. In this thesis a fuzzy logic speed controller is presented for adjustable speed DTFC based induction motors driven using two level inverter. Simulation results confirm the superiority of the presented controller in fast speed tracking capability over wide speed control range without affecting system stability. The speed control of an induction motor drive by means of the Artificial Intelligence (AI) based fuzzy logic technique using SVPWM concept has been investigated in this thesis. According to reference speed trajectory the fuzzy logic controller has shown good performance. The settling time of the torque, and speed matched with the desired values that were taken during the simulations. By the method presented in this thesis, the efficiency, performance and reliability of induction motor drive increases. Steady state error in speed control is acceptable and there is no any overshoot. In the previous research the conventional DTFC, the selected space voltage vector is applied for the whole switching period regardless of the magnitude of the torque error. Moreover, high torque ripples due to the selected space voltage vector always cannot generate the exact stator space voltage vector required to obtain the desired electromagnetic torque and stator flux linkage. In conventional direct torque, and flux control, the proportional plus integral (PI) controller when used as a speed controller needs its parameters to be retuned every time the set point is changed because the induction machine is highly nonlinear behavior. Experimental work of variable frequency drive of induction motor has been implemented, and include theoretical basics of voltage/frequency V/F control of induction motor its effect on flux linkage.