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Ferrite Core Parameters

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nec3

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What is the right way to define the main parameters (Bm, Al, Mi..) of a smsp ferrite so that we can choose its replacement?
 

power-twq

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The new ferrite core's BM should be same or greater than the old one,

AL should be enough large, we can adjust ferrite core's air gap to

adjust its inductor to required value.





nec3 said:
What is the right way to define the main parameters (Bm, Al, Mi..) of a smsp ferrite so that we can choose its replacement?
 

nec3

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At my first try i increased air gap to about 0.5 mm just for to make AC current of the input with no load same as the original.The circuit worked well up to 110 A DC output current without air cooling!!After that 30 USD is gone...Original core had no gap.Switching frequency is 100 KHz.Topology 2 transistor forward. Core E65/32/27
May be i should adjust air gap at DC output of 100A to reduce input power for efficiency??
Need Help.
 

VVV

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If you are trying to get a substitute for a certain ferrite, look at the following:
Shape availability
For the material mix, the saturation flux and the losses per volume unit at your operating frequency (usually at a temperature of 80~100°C). Compare these against the original.

The Al value is not really that important: for flybacks it is dictated by the airgap, so it depends very little on the actual ferrite material. For forward-derived topologies, it is generally sufficiently high. Slight variations will cause some change in the magnetizing current, but generally nothing serious. I never worry about it.
 

nec3

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If you are trying to get a substitute for a certain ferrite, look at the following:
Shape availability
For the material mix, the saturation flux and the losses per volume unit at your operating frequency (usually at a temperature of 80~100°C). Compare these against the original.

Yes Iam tring to get a substitute but for an unknown core.Saturation flux is too what I am really worriying most about.For instance difference is only 30 mT between 3c92 and 3c90.I am keeping try..
 

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