# Tranformers more efficient at resonance?

Discussion in 'General Electronics Chat' started by tonytt98, Sep 21, 2014.

1. ### tonytt98 Thread Starter New Member

Sep 21, 2014
2
0
Greetings all..

New guy here.

Question:
Would a transformer be more efficient at a pulsed AC resonant frequency?

I have this idea of finding a matching resonance frequency for the primary windings that would match the secondary winding's resonant frequency, and there for, you would have a more efficient transformer all around. Would this be true?

Thanks,
Tony

2. ### crutschow Expert

Mar 14, 2008
13,501
3,375
If that were true, transformers would be made resonant.
The efficiency of a transformer is determined mainly by it's winding resistance losses and the eddy current losses. Don't see how that would be significantly affected by making the transformer resonant.

3. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
515
Yes and No.; it depends upon what you mean or are trying to do.

It is not clear what sort of transformer you and circuit you mean.
Some transformers are designed for a wide frequency range of operations some for a very narrow band.

All transformers have a frequency response curve
Within a circuit there can be peaks in the curve due to resonances.
These paeaks are influence bu other circuit components, eg input capacitance.

This effect is taken into consideration in the design of trnasformers for audio purposes, input insterstage and output.

4. ### tonytt98 Thread Starter New Member

Sep 21, 2014
2
0
Example: Transformer used in a cell phone charger with an output capable of 5v +-5% at a max of 10 watts.
If the secondary windings are at resonance, is it outputting at maximum efficiency. I'm guessing there would be capacitors and voltage regulators after the secondary windings and the voltage may be up around 7v for the voltage regulator to operate properly.

So with this example, is it most efficient to have the primary and secondary windings resonating at there prime resonant frequency, with all other components on the primary and secondary circuits taken into account?

Thanks crutschow and studiot for your quick replies.

Tony

5. ### KL7AJ AAC Fanatic!

Nov 4, 2008
2,047
295
The transformer may or may not be more efficient at resonance. However, the entire SYSTEM will be because the power factor will be 1, which generally suggests the most efficient state.