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LLC resonant converter vs series resonant converter

Karla Drazenovic
Prodigy 15 points

Hi,

I'm little bit confused with the topology of series resonant converter shown in figure below

Why can we neglect transformer magnetizing inductance (it's not even shown in figure)? If we don't neglect transformer magnetizing inductance this would be LLC resonant converter, right?

I'm working on project where transformer magnetizing inductance is 40 uH and resonant inductance is 0.3 uH. Since magnetizing inductance is much bigger than series resonant inductance can I just neglect it?

When I simulate this converter with Lm = 40 uh and Lr = 0.3uH I got these:

And this result is very similar to LLC converter waveforms.

 

  • 0
    TI__Mastermind 32420 points

    Hello Karla,

    Thank you for your interest in TI LLC controllers.

    I am not an expert in LLC or series resonance, however, this application note may explain the benefits of LLC over the "strict" series-resonant converter.

    Please see the Introduction and early subsections A and B of part I of the text.
    Your simulation may work well at one specific line and load point, but may not work over wide ranges of conditions (where the LLC has advantages).

    There are several other app notes and documents to peruse at this location:

    Regards,
    Ulrich