Pulse Width Modulation (PWM) is a method of controlling the average power delivered by an electrical signal. It is a technique that generates variable-width pulses to represent the amplitude of an analog input signal. PWM is a type of digital signal that is used in a variety of applications, particularly for control. It allows us to vary how much time the signal is high in an analog fashion, which can be used to control the speed of a motor or the brightness of an LED.
In PWM, the signals energy is distributed through a series of pulses rather than a continuously varying (analog) signal. The signal produced will have a train of pulses, and these pulses will be in the form of square waves. The average value of voltage fed to the load is controlled by switching the supply between 0 and 100% at a rate. The percentage of time that the signal is high is called the duty cycle, and it determines the average voltage that is delivered to the load.
Three types of pulse-width modulation are possible:
- The pulse center may be fixed in the center of the time window and both edges of the pulse moved to compress or expand the width.
- The lead edge can be held at the lead edge of the window and the tail edge modulated.
- The tail edge can be fixed and the lead edge modulated.
Pulse width modulation is used in a variety of applications, including sophisticated control circuitry. It is commonly used in power electronics to control semiconductor devices.
