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LLC Gain Characteristics

Pixelx

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Is it possible to read such a characteristic from an LLC converter in practice?
I have such a converter and I would like to read such a characteristic from it. How to do it practically?
Or do you have any ideas what other characteristics can be obtained from it
 

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Yes just set up an LLC with a 50/50 oscillator whose frequency you can control with a pot, say ( i think the ICE2... can be controlled as such) ....then ensure you have a load on.....then vary the frequency and you will see the voltage rise as you reduce the frequency......but beware of going too low in frequency and getting severe reverse recovery.
Or you could cheat and use a UF diode in series with the FET, and a SiC diode in anti-pllel to the LLC fets....then you avoid rev rec...even if you "go over the hill".....read AN-4151 by onsemi (or is it Fairchild?) to see what that means.
 
you can't really get the exact same curves, as, the output diodes place a limit on the voltage you generate on the secondary at light load as you reduce the freq

you can take the LLC power parts, connect them on the bench ( or on a spare pcb ) and run a sig gen say 4V rms into the pri side in place of the fets, sine or square - makes little difference - then look at the Tx output, or after the sec side diodes with a very light load attached - then you can get these curves.

it is instructive to look across the L too, and the C

the sec side load will have to be stepped - and will be different ohms from a full power scenario.

You can do all of the above in LTspice too - a lot faster and with good results @Pixelx
 


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