In electronics, pulse width modulation (PWM) serves as a method for controlling a circuit’s power output by adjusting the width of the pulse signal. In Pulse Width Modulation (PWM), a constant frequency electrical signal, typically in the form of a square wave, is rapidly switched on and off. The duration of the “on” phase within the duty cycle is adjusted to produce the desired output.
In the context of PWM, the duty cycle represents the percentage of time that the output signal remains high during a complete cycle, highlighting the relationship between the active time and the total cycle length. The duty cycle can be understood as the ratio of the time a signal is active to the total time of the signal cycle, expressed as a percentage. To illustrate, with a duty cycle of 50%, the signal is in the “on” position for 50% of the complete cycle time.
Duty Cycle = 
The generation of a PWM signal is accomplished through the use of a comparator. Among the inputs to the comparator is the modulating signal, which encapsulates the information that is to be transmitted. In contrast, the second input is a non-sinusoidal waveform known as a Sawtooth wave, which acts as a reference signal. By assessing the two signals, the comparator generates a PWM signal that serves as its output waveform.
When the sawtooth wave exceeds the modulating signal, the output of the comparator will be in a “High” state. The degree of variation between the two signals dictates the output of the comparator, which defines the pulse width produced at the output. Each cycle of the sawtooth wave undergoes this process, leading to the generation of a sequence of pulses with variable widths that encode the modulating signal.
Trail Edge Modulation:- In this approach, the rising edge of the signal remains unchanged, whereas the falling edge is adjusted through modulation. Consequently, the output waveform has a uniform frequency, but the duty cycles vary. In applications that demand a stable frequency, Trail Edge Modulation is utilized to manage varying levels of power or intensity. This strategy is often applied in lighting contexts, notably in LED lighting, to adjust the brightness of the lights while preserving a uniform, flicker-free output.
Lead Edge Modulation:- State-of-the-art pulse width modulation (PWM) is utilized to control the amount of power delivered to a load. In state-of-the-art modulation, the modulation occurs at the leading edge of the pulse or waveform, with the trailing edge remaining unchanged. Controlling the average power delivered to the load can be achieved by modifying the width of the pulse’s leading edge. This approach is widely utilized in fields such as LED illumination, motor regulation, and power supply management.
Pulse Centre Two Edge Modulation:- The technique referred to as Dual Edge Modulation, or Pulse Center, is utilized within Pulse Width Modulation (PWM) to alter the timing of the signal’s leading and trailing edges. This approach consists of creating two sequential pulses that have identical polarity but vary in their respective pulse widths. The intersection of the two pulses acts as the reference point, marking the center of the waveform. The effective duty cycle of the PWM signal can be altered by adjusting the width of the pulses, all without affecting the frequency. In the realm of power electronics, Pulse Center Modulation is often employed in various applications, such as controlling motors, operating power inverters, and regulating voltage.
The application of Pulse Width Modulation (PWM) in telecommunications involves encoding digital signals onto an analog carrier wave. The mechanism varies the width of pulses in a continuous train of periodic signals to represent data. This technique is utilized in several applications, including remote control systems, audio and video transmission, and motor control.
PWM is employed to mitigate the risk of overheating in electronic circuits. By adjusting the time a signal spends in the “on” state versus the “off” state, it is possible to control the average power provided to a load. This enhances the efficiency of the circuit’s operation and lowers the heat output.
In motor control applications, PWM is utilized to create outputs that can vary in speed. By manipulating the duty cycle of a PWM signal, one can effectively control the speed of a motor. Common applications of this technology include robotics, electric vehicles, and industrial machinery.
A clear demonstration of this concept is found in electric scooters, where the controller generates a PWM signal with a duty cycle that corresponds to the speed the user wishes to achieve, triggered by the action of twisting the throttle. This method provides accurate speed regulation, economic efficiency, and long-lasting performance by minimizing mechanical strain and overheating, which contributes to a smooth and secure driving experience. Furthermore, it removes the necessity for intricate analog circuits and costly components.