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OK, the coils work by magnetizing the ferrite cores, I'm sure you know.. But use the laws of physics to visualize how the magnetic field of the magnetized ferrite choke appears (simulation is one way), and try to place the other chokes so that the magnetic fields of the chokes does not interfer with one another, or at least interfer as little as possible..
One simple way is to place the ferrite chokes next to one another and add a GROUND GUARD BAND between both of them, with the band/ copper connected to the chassis ground. This may reduce the coupling to a certain extent.
Placing common mode chokes one next to the other should not be an issue.
Hello all,
this topic also greatly interests me. For power(~4A) filter especially for SMPS, I usually use coil(~50uH) wrapped around toroid ferrites and separate them by big electrolyte capacitors(4700uF). I don't know how good is this approach is. I never measured efficiency drop due to interference of neighboring coils. Is there a simulation or something that can give a rough estimate for the effect of distance and angle on efficiency drop.
Johnson, I downloaded the sheet of the device you referred to, I saw flat very thin black butterfly shaped sheets on the board, I'm not familiar with these parts, what is beneath them(are they ferrite sheets cut in this shape?), what is their name so I can find their datasheet and information? are they used for high current (>4A) filter?
"black butterfly shaped" component is the air gapped ferrite, also please note that this is isolated converter, the coil(topic of disscution) is implemented in PCB. The PCB is also very thick, 2.5mm.
Also the current rate is from 25A to 60A, input voltage 48-60V and output 1.2, 1.5, 3.3 and so on.
then what you mean it is implemented in PCB? thick copper wires will be wound around their axis right? why PCB needs to be thick?
25-60A! thats alot then current can't be carried out by tracks. all should be carried out by thick wires. how they fix these wires on PCB?
thanks a lot
then what you mean it is implemented in PCB?
- the coil winding is the round traces on PCB
thick copper wires will be wound around their axis right?
- yes
why PCB needs to be thick?
- I do not know exactly why, I suggest it is the problem of heat dissipation and high current.
25-60A! thats alot then current can't be carried out by tracks. all should be carried out by thick wires. how they fix these wires on PCB?
- yes, 60A! it is true I have test on of them for 3.3V, it is exactly what it claims! They use very special mosfets at closest distance to output pins,
hello,
Johnson I'm a little bit confused you acknowledged that wires are wound along axis of parts in photo then you say coil winding is round traces on PCB(from round you mean zigzag, right?). possibly the ferrites in photo are not what you are talking about. I also checked murata site. air gapped ferrite returns nothing. google returns 13 hits for"air gapped ferrite" non of them commercial. also digikey has no record of it.
Another question is how they are mounted on PCB(screw, spacer,...?)
About using tracks as coil winding, can Altium designer calculate inductance of such tracks? (giving it the distance to a ferrite sheet?) how should I calculate the inductance of tracks on PCB?
Thanks
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