INTRO_Labsguru_LGEC016.pdf (Size: 323.7 KB / Downloads: 56)
Now a days DC motor plays a vital role in most of the industrial areas, it can be seen in most of the
electronic devices. They are mainly used for the mechanical movements of physical applications
such as rolling the bundle of sheets or CD drives, lifts etc.
Many methods evolved to control the revolution of a motor. DC motors can be controlled either
by software or directly by hardware. Software controlling needs computers which are bulky and
common man cannot afford for it, so hardware controls are in use. Even in hardware if it is
programmable device then it is preferred because it can be modeled according to the requirements
of the user.
The first thing that can be controlled in a motor is its direction of rotation. Direction of the motor
can be controlled by controlling the polarity of the current flowing through it. Usually a DC
motors are driven by famous H-Bridge circuits made up of either transistors or the buffers or any
other suitable methods.
Controlling the speed of the motor is another important area to be considered. The speed of motor
is directly proportional to the DC voltage applied across its terminals. Hence, if we control the
voltage applied across its terminal we actually control its speed.
PWM is a common technique for speed control. A good analogy is bicycle riding. You peddle
(exert energy) and then coast (relax) using your momentum to carry you forward. As you slow
down (due to wind resistance, friction, and road shape) you peddle to speed up and then coast
again. The duty cycle is the ratio of peddling time to the total time (peddle +coast time). A 100% duty
cycle means you are peddling all the time, and 50% only half the time.
The aim of objective of this project is to control the speed of DC motor using microcontroller.
The other fundamental objectives of the system include:
Correct programming of microcontroller.
Proper interfacing of motor drive and microcontroller.
This circuit allows you to control the speed of a DC motor from microcontroller. Basically, there are
three ways to vary the speed of DC motors:
Use a gear-box.