Electronics > Power/Renewable Energy/EV's

Who knows what kind of SMPS is this one ?

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ym58:
@2N2222A : thanks for your academics reminders, that will surely help those whose EE knowledge is poor to dare tackling SMPS issues ;) !
I will swap the output stage electrolytic caps (i.e. C19 and the likes) from this board with newer ones (maybe 25V besides, as these are 16V, which is kinda marginal as I tweaked the SMPS to 14.6V) but honestly I feel that the area I should rather investigate is 'upstream' ... I think I will have to dig out my scope :bullshit:!
In the past years, I hacked numerous power SMPS to convert them into LFP4 or Li-Ion chargers (from 4S to 10S) like in this thread but this one really sucks ... its particular topology with the two tiny transformers (see pic in OP) isn't really familiar to me (not a flyback, nor a half-bridge ...  :-//)

madires:
As already suggested, one of the small transformers could be part of a flyback SMPS (standby or for SMPS control) while the other one is driving the MOSFETs. The circuit isn't complex and can be reverse engineered without much effort.

f4eru:
culprit could well be the AUX winding supply of the regulator putting a too high voltage to the chip, having all sorts of bad effects.
It could also be the regulation being marginal, and getting unstable with the higher loop gain....

Etc....

ym58:

--- Quote from: madires on December 05, 2022, 03:24:14 pm ---(...) The circuit isn't complex and can be reverse engineered without much effort.
--- End quote ---
Yeah I know, you're right @madires ...  but I've been 'reversing' so often that I'm kind of weary now :=\, very time-consuming for what it's worth !
But anyway, some good news at least for tonight, it looks like the HV caps (the ones in series) were a bit weary too ;)
I replaced them with newer caps (470uF/200V) I had handy somewhere back on my shelves and the PSU now works much better and bears 25A without frying the Mosfets and gate components !
( @2N2222A : I think @faringdon hints and my feeeling were right, the output stage caps were not the culprits :-+ )
The SMPS is now under test connected to an inverter + water heating resistor (250W) ... so far so good.
---
Next step : I will try to output 50A to charge LFP4 batteries ... but for the time being : no rush (I don't have any 20N60C3 left) !

2N2222A:

--- Quote from: ym58 on December 05, 2022, 06:06:13 pm ---But anyway, some good news at least for tonight, it looks like the HV caps (the ones in series) were a bit weary too ;)

--- End quote ---
So you changed those too, meaning you also changed the output stage capacitors in addition to the HV mains input ones?

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