الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In this thesis a new scheme for multi-speed operation of single phase induction motors is presented. This scheme depends on controlling both the fundamental frequency and the rms value of the voltage supplied to the stator of the motor. This changes the speed of the motor as a result. Frequency control is achieved by using integral half cycle control of the supply voltage. To obtain the motor rated torque at the different speeds, the rms value of the applied voltage should be controlled. The rms value of the applied voltage is controlled using a TRIAC connected in series with the stator of the motor. The TRIAC is used to control the power circuit. The TRIAC firing pulses are produced and controlled using a PIC16F877A microcontroller which is programed using microC language. To control the frequency of the applied voltage, the supply zero voltage crossing point is obtained to synchronize the TRIAC firing angle with the applied voltage. The motor applied voltages at the different speeds are scored. The circuit is a constant V/F control circuit.