What does pwm do

It was followed by the use of ordinary resistors to slow the fans down, fans equipped with thermal resistors, various potentiometers for a wide range manual speed control, etc. But nowadays, if you want to control the speed of your fans and pumps, PWM control is the way to go. Every mainstream motherboard that leaves the factory today is equipped with at least one 4-pin PWM header. However, even today, many years after the introduction of PWM in , there are users that are still not familiar with its advantages.

And worse, there are serious companies out there that make advanced and well-designed fans with old-fashioned 3-pin connectors. Therefore, we will explain what PWM actually is, how it controls the speed of fans and pumps, and we will also show you an example of a PWM profile in one of the software provided by the motherboard manufacturers.

By the number of wires — pins that a fan has — we can distinguish three main types of connections. A signal is sent via this third wire with a certain frequency that is proportional to the fan speed, expressed in RPM revolutions per minute.

The third type of fans that use four wires are PWM fans and that is what will be discussed in this article, along with PWM pumps. PWM Pulse Width Modulation or modulation with the width of an impulse, is a widespread term in the world of electrical engineering. It has a broad range of application, like in the field of telecommunications, audio equipment, servo motors, etc.

Interesting for us enthusiasts is the application of PWM in voltage regulation. Some of you probably already know the principle on which pulse width modulation PWM works, but nevertheless, we will explain how it actually controls the speed of a fan or a pump.

In short, PWM operates like a switch which constantly cycles on and off, thereby regulating the amount of power the fan or pump motor gains. To have a better understanding how this works, take a look at the chart bellow.

So, the motor is being fed impulses of power. They turn the current fully on and fully off. They just vary the amount of time that it is on instead. The additional heat generated by traditional transistor circuits is another consideration, as it may increase the amount of time that cooling fans have to stay on to reduce the temperature of said devices.

The tiny power source controls the large one with the help of power transistors. This concept is what enables highly sophisticated microcontrollers often called MCUs and other computers to control very large currents at a reasonable cost. You must log in to post a comment. Skip to content. Applications range from controlling DC motors and light dimming to heating elements. Share this Term. Related Terms Modulation Frequency Modulation. Quadrature Amplitude Modulation. Tech moves fast! Stay ahead of the curve with Techopedia!

Join nearly , subscribers who receive actionable tech insights from Techopedia. You might have gathered by now that PWM, duty cycle, and frequency are interrelated. We use duty cycle and frequency to describe the PWM, and we often talk about frequency in reference to speed. For example, a variable frequency drive motor produces a response like analog device in the real world. The separate pulses that the VFD motor gets are not discernable to us; as far as we can see, the pulses are so fast usually somewhere in the milliseconds that by real world standards it just seems like a motor ramping up.

The duty cycle can change to affect the average voltage that the motor experiences. The frequency of the cycles can increase. The pulse can even be increased in length.