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Help me reduce spike voltage and ring voltage frequency in flyback RCD snubber

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tictac

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Hi
I Simulate one flyback switching power supply with this specification in Orcad 16 cadence.
Vin=24 v (DC) Vout=1300 v (DC) Iout=40 mA
L1=43uH L2=150mH coupling=0.99
I have a problem in snubber circuit. I want to reduce spike voltage to minimum range and reduce ring voltage frequency. is it possible?
please help me to improve it.
 

dick_freebird

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flyback RCD snubber

This involves the self-capacitance of the switch and the
inductor and so on. If it were me, I would just run a loop
of R and C values and inspect the waveforms for the
cleanest switching. I'm sure there are better methods
if you know all the inputs to the equation, but the shotgun
is a proper tool for many circumstances.
 

    tictac

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tictac

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Re: flyback RCD snubber

I'm sure there are better methods
if you know all the inputs to the equation

hi
can you tell me about that,please? or give me some article about this methods?
 

FvM

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flyback RCD snubber

The bad thing with the RCD snubber is, that it's even causing additional losses without any inductive overvoltage. In my opinion, you can simply burn the spikes in the MOSFET's built-in overvoltage clamp, as long as it can stand the power dissipation. It's designed for this mode of operation.

The better alternative is a circuit, that recycles the leak inductance energy to the bus voltage. Unfortunately, it requires two (complementary) switches and two free-wheeling diodes.
 

    tictac

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tictac

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Re: flyback RCD snubber

hi and thank you
I cant change my citcuit topology. I want to improve it with one switching mosfet. could you give me one circuit for this?
or practical article about it?

by regards.
 

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