06-08-2011, 02:46 PM
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ABSTRACT
The aim of the project is to design the speed control of AC motor using PWM technique. A pulse width modulator (PWM) is a device that may be used as an efficient AC motor speed controller or light dimmer. This project is a versatile device that can control AC devices which draw up to a few amps of current. The circuit may be used in either 12 or 24 Volt systems with only a few minor wiring changes. This device has been used to control the speed of the AC motor and to control brightness of an automotive tail lamp. One additional advantage of pulse width modulation is that the pulses reach the full supply voltage and will produce more torque in a motor by being able to overcome the internal motor resistances more easily. Two push-to-on switches are provided for increasing / decreasing the speed of the motor. Two more push-to-on switches are provided to rotate the motor in Clock wise / Counter clock wise direction. 16X2 LCD is connected to display the speed level of the motor and the direction. LED indication is also provided for visual indication. A buzzer is provided for audio indication of AC motor speed variation and change in direction. Whenever the speed is increased / decreased, the system acknowledges by a short beep. This buzzer is driven by transistor driver circuit.
BLOCK DIAGRAM
HARDWARE REQUIREMENTS
• 89C51 IC
• LCD
• BUZZER
• DC MOTOR
• OPTO-COUPLER
• CRYSTAL OSCILLATOR
• RESET SWITCH
• REGULATOR
• TRANSFORMER
• BRIDGE RECTIFIER
SOFTWARE REQUIREMENTS
• 89C51 C COMPILER
• 89C51 IC PROGRAMMER
