DC output vs AC input in rectifier

[ravindranathan]

How is DC output voltage of a full wave rectifier higher that AC input voltage?

 

[LionelHutz]

Peak vs RMS voltage. It's not always more. A single phase rectifier feeding a resistive or inductive load it is less.

 

[jraef]

What we call AC voltage level is actually the RMS voltage, meaning Root, Mean, Squared, a complex form of averaging across a time period. The peak of that RMS voltage is higher than the RMS, by a factor of 1.41:1, but across time it appears lower in terms of what AC devices actually use/respond to.

But when you run the AC through a bridge rectifier, the diodes only conduct when the AC sine waves approach the actual peaks, so the net voltage created is a rippled DC level and if you smooth out the ripple with capacitors and/or inductors you end up at that 1.41 x ACRMS value for the DC.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[waross]

That is for an unloaded circuit.
When the circuit is loaded the voltage will drop.
How much the voltage drops depends on the filtering and the amount of loading.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

jraef - smoothing with an inductor produces a DC voltage that is about 0.89Vrms.