Ripple factor formulas for rectifiers?

[akyip]

Hi guys,

I have a question about two different ripple factor formulas that I've seen.

One is: ripple factor = √[ (Vrms / Vavg)^2 - 1]

The other I've seen is: ripple factor = Vac / Vdc

I'm just trying to understand the difference between these two ripple factor equations I've seen for rectifiers so far. I would appreciate if someone can help clarify the difference between these two formulas.

From what I understand, the first formula uses the DC RMS and DC average output voltages of the load. The second formula uses the input AC RMS voltage and DC output load voltage.

Again, I hope someone is able to clarify the difference between these two ripple factor formulas that I've seen so far. I appreciate the time spent by anyone answering this question.

Thank you!

 

[Orchid PE]

Both equations are correct, but which one to use depends on what values you are given in the problem.

Ripple Factor, RF, is defined as RF = Vac / Vdc. It's the ratio of the ac component to the dc component.

Vrms is defined as the square-root of the Vac and Vdc components squared.

We can find Vac by rearranging the equation such that Vrms and Vdc are on the same side. Once we find the equation for Vac, we can then divide it by Vdc.

Note that Vac in all these equations is an rms value.

Vavg that you listed in an equation above is really the Vdc component.

 

[akyip]

This explanation is simple yet really helps. Thank you, Chattaneer!