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  1. #21
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    Re: Flyback Airgap Doubts?

    (i'll say nothing, i got my brains smashed up once when asked to design Cuk's single stage isolated PFC'd Cuk converter for an EV charger at 3000W...after a week, all i had was a sim which didnt seem to work that well, so i got taken off the job....i seem to remember they also wanted it bidirectional...could be wrong about that bit)
    sorry to go off topic....OP please send latest schem etc and ill take a look



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  2. #22
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    Re: Flyback Airgap Doubts?

    Isolated PFC Cuk @ 3kW is only for the power electronics engineer with 15+ years of solid experience ...


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  3. #23
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    Re: Flyback Airgap Doubts?

    if i recall, cuk converters need to be individually tuned by gapping the
    inductor one at a time
    please forgive me if i remember incorrectly


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  4. #24
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    Re: Flyback Airgap Doubts?

    you recall incorrectly ... tuning, as such, was only ever required if you wished to get close to minimum current ripple on the coupled inductor AND transformer variants - it is possible to design the coupled chokes - such that very close to minimum ripple is achieved without adjustment.


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  5. #25
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    Re: Flyback Airgap Doubts?

    If I want to avoid the RCD snubber from the primary, what are my options?



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  6. #26
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    Re: Flyback Airgap Doubts?

    its a flyback so you cant avoid the RCD clamp....if you dont like it you could do a two transistor forward instead.



  7. #27
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    Re: Flyback Airgap Doubts?

    no @treez i didnt mean to completely remove it ,, I was talking about an alternative like zener clamp etc


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  8. #28
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    Re: Flyback Airgap Doubts?

    Thats probably the only other one.....the zener or TVS clamp.....there is the RCDZ clamp which reduces rcd clamp dissipation in light or no load.
    Power integrations used to have app notes on it.
    There's also the RCD clamp with a slow diode so that the leakage current can ring back out of the rcd capacitor and therefore not cause so much dissipation in the rcd resistor....it was another power integrations invention but they seem to be distancing themselves from it now.



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