Introduction to speed control technique:
There are several techniques for controlling the speed of DC motor. Some of techniques used are rheostat and chopper control technique which are not that much effective. In this project we are going to employ PWM technique for controlling the speed of DC motor.
We need to fabricate a astable and a monostable mutivibrator to a IC556 dual timer to obtain the required pulse. By using IC556 dual timer the modulate output is obtained , which is used to control the speed of motor. The IC556 dual timer works on a supply voltage of +5 to 18v. Here astable produces a square wave which is fed to the trigger pulse of the monostable multivibrator. Then the circuit produces pulses with variable width. The generated variable pulse is given to drive the circuit which controls the speed of the motor.
To obtain the required speed of the DC motor , certain tests are performed to check the speed of the motor. First the PWM circuit is tested the waveform is tested for each pulse of the output voltages so that the changes occurred can be rectified. Then the speed of the motor is tested for varying voltages and the varying speed of motor is noted for every rise in voltages. Thus we conclude that the PWM technique is the most efficient for controlling the speed of the DC motor.
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