Pulse Width Modulation is a method of reducing the average power delivered by an electrical, by effectively cutting it up into several equal parts. By turning the switch between the supply and load on and off at a very fast rate the average value of the voltage and current fed to the load can be controlled. The longer the switch is on compared to the off period, the higher the total power supplied to the load.
PWM is particularly used for running inertial load which is not as easily affected by the discrete switching because their inertia caused the components to react slowly. The switching frequency of the PWM has to be high enough not to affect the load, that is to say, the resultant waveform perceived by the load must be as smooth as possible. The rate or frequency at which the power supply must switch on can vary greatly depending on load and application. The main advantage of PWM is that the power loss in switching devices is very low.
When the switch is off there is practically no current, and when it is on and power is being transferred to the load, there is almost no voltage drop across the switch. Power load is the product of voltage and current, is thus in both cases zero. The PWM signal consists of two main components that define its behavior, the duty cycle, and frequency.
The duty cycle describes the amount of time the signal is in and on the state as a percentage of the total time it takes to complete one cycle. The frequency determines how fast the PWM completes a cycle for these reasons. PWM signal is one method of generating an analog signal using a digital source.
Types of Pulse Width Modulation (PWM) Techniques
- Lead Edge Modulation
- Trail Edge Modulation
- Phase Correct PWM
Application of Pulse Width Modulation
- PWM Techniques are used in Telecommunications for encoding purposes.
- Pulse Width Modulation helps in voltage regulation and thus finds its use in controlling Brightness in Smart Lighting Systems and also controls the speed of motors.
- The computer Motherboard requires PWM Signals that control the heat generated on the board. 4 Pin PWM header is embedded in the fan that helps to dissipate the heat from the motherboard.
- It is also used in Audio/Video Amplifiers.
- It is also used to control DC motor
Pulse Width Modulation (PWM) With Arduino
You will know what PWM is, and see its effects on an LED, I will demonstrate the PWM with the Arduino
- Arduino Prototype Board
- Breadboard and Jumper Wires
- 1x 1K Resistor (Brown, Black, Black, Brown, Brown)
Note: The LED will not be damaged if it is placed in backward, however, it will not light until it is swapped to the correct direction.