Pulse Width Modulation (PWM):
It is modulation technique in which the width of pulse or digital control signals changes with respect to time keeping frequency and amplitude constant. It is used to control the power delivered to any load. It is mainly used to control analog devices.
PWM has low power loss and high efficiency therefore it is used in wide range of operation.
Generation of PWM Signal:
By using comparator we can generate the PWM signal. By applying triangular wave to the non-inverting terminal and control voltage to the inverting terminal we get PWM signal at the output of comparator. When triangular wave voltage is less than the control voltage then output of comparator gets low, and when the triangular voltage is greater than the control voltage then output of comparator become high. The width of pulse depends on value of control voltage.
As control voltage reduces the width of pulse increases and vice versa.
Switching frequency defines as how fast switching takes place. If the switching frequency is higher, then the greater number of times switches changes per second.
The Duty cycle defines ON time of pulse. It is ratio of ON time of pulse to total time period. It is expressed in %.
Duty Cycle= Ton/T*100%
If the duty cycle is 25% that means the pulse ON for 25% of the time.
If the duty cycle is 50% that means the pulse ON for 50% of the time.
If the duty cycle is 75% that means the pulse ON for 75% of the time.
Application of PWM: