Browsing by Author "Umar Zafar, Muhammad"

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    Automatic soft starting control of single phase induction motor
    (University of Management and Technology, 5/24/2013) Adnan Akram; Muhammad Qasim; Umar Zafar, Muhammad
    The electrical machine that converts electrical energy into mechanical energy is the workhorse of motion industry, and when the output speed of the motor is controlled by changing its input frequency, and then the drive is called variable speed drive or variable frequency drive. Presently, it is just the combination of a motor and a controller. Drives can be classified as... 1) DC Drives 2) AC Drives The control of dc motors requires providing a variable dc voltage which can be obtained from dc choppers or controlled rectifiers. These voltage controllers are simple and less expensive. DC motors are relatively expensive and require more maintenance due to brushes and commutates. While the control of AC drives require complex control algorithms by microprocessors or by microcomputers commonly known as controllers. The AC motors have number of advantages e.g. 1) They are 20% to 40% lighter than equivalent dc motors. 2) Applications of variable speed ac motors with inverter control include crane hoists, blowers, pumps and textile plants etc. Induction motor control is complex due to its nonlinear characteristics. The speed and torque of induction motors can be controlled by following methods, a) Stator voltage control b) Voltage control Rotor c) Frequency control d) Stator Voltage and frequency control e) Stator current control f) Voltage, Current and Frequency control In this project we have controlled the speed of induction motor by stator voltage and frequency control method using AVR micro microcontroller. The complete circuit consists of two parts; stator voltage control circuit and frequency control circuit. The stator voltage control circuit consists of PWM Program, Gate Drivers and Opto-couplers and frequency control circuit consist of proximity sensor.