Microcontroller Based Dc Motor Conditioning and Monitoring System

4510 Words Dec 1st, 2012 19 Pages
Microcontroller based DC motor Speed Conditioning and Monitoring System


The proposed system is based on concept of monitoring and control of the various speed of a DC motor. The speed of DC is monitor by optical decoder sensor and which is being collcted on a microcontroller which will subsequently control the DC motor through a motor driver circuit. The values of the speed also displayed on an LCD. The DC motor speed can be set controlled manually using a keypad.(3)

The proposed project is based on the concept of measuring and displaying the speed of motor. The system uses a hall sensor for sensing and optical encoder unit for speed (RPM) measurement. A magnet attached on the shaft of the motor
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The current flow through the motor drops as the rotational speed increases, and a free-spinning motor has very little current flow. It is only when a load is applied to the motor that slows the rotor that the current draw through the motor increases.

"In an experiment of this kind made on a motor with separately excited magnets, the following figures were obtained:

|Revolutions per minute |0 |50 |100 |160 |180 |195 |
|Amperes |20 |16.2 |12.2 |7.8 |6.1 |5.1 |

Apparantly, if the motor had been helped on to run at 261.5 revolutions per minute, the current would have been reduced to zero. In the last result obtained, the current of 5.1 amperes was absorbed in driving the armature against its own friction at the speed of 195 revolutions per minute."(6)

D.C. Motors:

Direct current motors are used in many applications that require adjustable speed. In uses requiring quick stops, a dc motor can minimize the size of a mechanical brake or make it unnecessary. This is done by dynamic braking (motor-generated energy fed to a resistor grid), or by regenerative braking (motor-generated energy returned to the ac supply). DC motor speed can be controlled smoothly down to zero, followed immediately by acceleration
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