DC Motor intro
DC motor is a device which converts electrical energy into kinetic energy. It converts the DC power into movement. The typical DC motor looks like
A typical 5V battery can supply the required energy for the DC motor to serve projects which need a tiny amount of torque at constant or variable speed. The variable speed can be achieved by Pulse Width Modulation concept.
PWM Concept
PWM is short form of Pulse Width Modulation, where the electrical pulse fed to the DC motor or any device has varying width depending on the need, in other words the energy is not supplied to the motor at all the times. The supplied power is regulated wrt time to generate the varying width of the pulse over a period of time.
The typical PWM wave appears as
Observe the variation in pulse width. The width of the pulse changes wrt time.
Controlling DC motor with PWM
The concept of DC motor control involves feeding the PWM wave to DC motor and in turn controlling the speed of the motor over a period of time. The time for which the amplitude of the pulse is nonzero is called the on time of the pulse and this value is used in determining the duty cycle of the pulse.
Duty cycle indicates the percentage if the time the pulse amplitude is nonzero. For example if the pulse amplitude is nonzero for 50% of the time then the duty cycle is 50%.
Role of Arduino
Generating the PWM can be done with any processor/micro controller. The wave is generated by programmatically turning on and off of the signal at micro controller pin.
Arduino makes the programming and interfacing with various sensors easy. In second part of the post we will see how to interface DC motor with Arduino.
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