Pulse Width Modulation: Controlling Power in Electronics

by Yuvi K - December 17, 2023

Pulse Width Modulation (PWM): Controlling Power in Electronics

Pulse Width Modulation (PWM) is a popular technique in electronic engineering. It is a way to get an analog signal from a digital input. It is used in electronics to control power levels in circuits. Generally, PWM is used in applications such as motor control, load control, light dimming, analog to digital impedance conversion, and in power electronics applications.

What is PWM?

Pulse Width Modulation (PWM) is a modulation procedure where the duration of an electrical pulse is varied to convey information. In this technique, the pulses are usually square waves which are generated with variable duty cycles. The length of the pulse is known as the “duty cycle”. The duty cycle can be as low as 10% or as high as 90%.

In simple words, PWM is a way of varying the voltage and current in digital circuits. This technique is used to create a pulse that has a different width depending on the amount of power being delivered. The width of the pulse needs to be varied to accomplish the task of controlling the power.

How does PWM Work?

To understand the working of PWM, consider a voltage source with a constant voltage output. A PWM is applied to the voltage source, creating a rectangular wave with two discrete values. This waveform is known as a rectangular wave, or a pulse width waveform.

The value of the output signal is set by adjusting the duty cycle of the waveform, or the ratio of the total pulse width to the total cycle time. By changing the ratio of the pulse width to the total cycle time, the output voltage can be adjusted.

Types of PWM

The different types of PWM signals are:

Sinusoidal Pulse Width Modulation (SPWM): The SPWM signal is a sinusoidal waveform with a variable duty cycle. It is used to achieve more efficient power outputs.
Ratio Control Pulse Width Modulation (RC PWM): In this type of PWM, the output signal is determined by a general frequency setting and a ratio control. The ratio control is carried out using a variable resistor or a potentiometer. In this type, the ratio between the output and the input is fixed.
Averaging Pulse Width Modulation (APWM): The APWM signal is generated using a triangular waveform and a reference voltage input. It is also known as average-mode PWM.
Sector-Selective Pulse Width Modulation (SSPWM): The SSPWM signal is generated using two same-frequency sine waves and a reference voltage. This signal is used for higher precision in power control.

Advantages of PWM

Accuracy: PWM signals provide precise control over both power output and speed. This allows engineers to deliver more accurate power levels in circuits.
Efficiency: The PWM technique requires less equipment and provides more efficient power control. This leads to higher efficiency levels in the system.
Durability: The PWM technique is technical robust as compared to other modulation techniques. This leads to high-durability systems.
Cost Savings: The PWM technique requires fewer components and is more energy efficient. This leads to less cost expenditure for the system.

Applications of PWM

Motor Control: One of the most popular applications of PWM is in motor control. PWM is used to control the speed and position of electric motors, such as dc motors, servo motors, induction motors, and stepper motors.
Solar Tracking System: PWM is used in the solar tracking system to control the current feed to the solar controller. This system is used to adjust the output of the motor to track the sun’s position during the day.
Light Dimmers: PWM is used in light dimming systems to adjust the brightness of the lights. This technique is used in rooms to adjust the brightness according to the user’s requirement.
Analog To Digital Impedance Converters: PWM is used in analog-to-digital impedance converters to programmably change the load impedance in a circuit.

Conclusion

Pulse Width Modulation (PWM) is a popular technique in electronic engineering. It is used in various applications such as motor control, load control, and light dimming. PWM is used in circuits to control current and power levels in the circuit. There are four different types of PWM signals: SPWM, RC PWM, APWM, and SSPWM. Some of the advantages of this technique include accuracy, efficiency, durability, and cost savings. It is used in applications such as motor control, solar tracking systems, light dimmers, and analog-to-digital impedance converters.