{"id":272,"date":"2023-06-28T07:41:57","date_gmt":"2023-06-28T07:41:57","guid":{"rendered":"http:\/\/localhost\/embeddedwala\/?p=272"},"modified":"2023-07-27T04:14:11","modified_gmt":"2023-07-27T04:14:11","slug":"pulse-width-modulation-pwm-an-introduction-and-applications","status":"publish","type":"post","link":"https:\/\/embeddedwala.com\/beta\/blogs\/digital-communication\/pulse-width-modulation-pwm-an-introduction-and-applications\/","title":{"rendered":"Pulse Width Modulation (PWM) : An Introduction and Applications"},"content":{"rendered":"\t\t
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What is PWM?<\/p>

Pulse width modulation\u00a0(PWM)<\/strong>\u00a0is a method used in electronics to control the power output of a circuit by modulating the width of a pulse signal. In PWM, a fixed frequency electrical signal, often a square wave, is turned on and off at a rapid rate, and the width of the “on” part of the duty cycle is varied to achieve the desired output.<\/p>

Duty Cycle of PWM :<\/p>

The duty cycle of a\u00a0PWM<\/strong>\u00a0signal is a measure of the proportion of time during each cycle of the signal that the signal is in its “on” state, which is typically a high voltage state. Essentially, the duty cycle is the fraction of time that the signal is in its “on” state relative to the total time of the signal cycle, expressed as a percentage. For instance, if the\u00a0duty cycle<\/strong>\u00a0is 50%, the signal is in its “on” state for half of the signal cycle duration.<\/p>

\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Turn on Time<\/strong><\/p>

Duty Cycle\u00a0 \u00a0 =\u00a0 \u00a0 —————————————<\/strong><\/p>

\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Turn On Time + Turn Off Time<\/strong><\/p>

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Process for generating the pulse width modulation :<\/b><\/p>

To generate a pulse width modulation\u00a0(PWM)<\/strong>\u00a0signal, a comparator is used. The comparator has two inputs – one is the modulating signal that represents the information to be transmitted (such as the desired power level for a motor), while the other input is a non-sinusoidal or Sawtooth wave that serves as a reference signal. The comparator compares these two signals and generates a\u00a0PWM<\/strong> signal as its output waveform.<\/p>

If the saw tooth wave is greater than the modulating signal, the comparator output will be in a\u00a0“High”<\/strong>\u00a0state. The magnitude of the difference between the two signals determines the comparator output, which defines the width of the pulse generated at the output. This process is repeated for each cycle of the saw tooth wave, resulting in a train of pulses with varying widths that encode the modulating signal.<\/p>

Types of Pulse Width Modulation Technique :<\/b><\/p>

\"\"<\/p>

There are three conventional types of pulse width modulation technique and they are named as follows:<\/strong><\/p>

  • Trail Edge Modulation:-<\/strong>\u00a0Trail Edge Modulation is a technique used in pulse width modulation (PWM) to control the duty cycle of the output signal. In this technique, the rising edge of the signal is kept fixed, while the\u00a0falling edge is modulated<\/strong>. This results in a constant frequency output waveform, but with varying duty cycles. Trail Edge Modulation is used in applications where a fixed frequency is required, but with varying power or intensity levels. This technique is commonly used in lighting applications, such as\u00a0LED lighting<\/strong>, where it is used to control the brightness of the lights while maintaining a constant flicker-free output.<\/li><\/ul>
    • Lead Edge Modulation:-\u00a0<\/strong>Leading edge pulse width modulation (PWM), is a technique used to control the power delivered to a load. In\u00a0leading edge modulation<\/strong>, the leading edge of the pulse or waveform is modulated, while the trailing edge remains fixed. By varying the width of the pulse’s leading edge, the average power delivered to the load can be controlled. This technique is commonly used in applications such as LED lighting, motor control, and power supplies. Leading edge modulation is also used in high-frequency switching power supplies to improve efficiency and reduce electromagnetic interference.<\/li><\/ul>
      • Pulse Centre Two Edge Modulation:-<\/strong>\u00a0Pulse Center or Dual Edge Modulation is a technique used in Pulse Width Modulation (PWM) that modifies the timing of\u00a0both the leading and trailing edges of the PWM signa<\/strong>l. This technique involves the generation of two consecutive pulses of the same polarity but with different pulse widths. The center point of the two pulses is the reference point or center of the waveform. By adjusting the width of both pulses, the effective duty cycle of the PWM signal can be changed without altering the frequency. Pulse Center Modulation is commonly used in power electronics applications such as motor control, power inverters, and voltage regulators.<\/li><\/ul>

        Applications of Pulse Width Modulation<\/b>\u00a0(PWM) :<\/b><\/p>