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Registered Member #61406
Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268
Hi I've got a 4ms pulse at 15volt which I'm feeding a lead acid battery, through a transformer, and I'm simulation the battery by a 13volt zener and a 0.1ohm reisistor.
The question is what physical trans to select, the pulse is 3amp,at 13-20volt. Thanks
Registered Member #61406
Joined: Thu Jan 05 2017, 11:31PM
Location:
Posts: 268
The pulse is 4ms wide, and happens every 200ms,it is about 3amp,with a voltage of 15-20volt. What type of transformer to use, ferrite or steel. The simulation works at 100mH prim/sec Does the wire gauge need to have a size for 3amp continues. It will be a pulsed dc, will that effect much. Cheers
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
There are several limitations on wire. You have to go with whichever bites first, whichever is the most restrictive. There's heating, for which you use RMS current. 3A/mm2 is a rule of thumb for small transformers, though if it's sparsely wound (that is, well cooled) you can go above that a bit. There's voltage drop, for which you use current and resistance, and will depend on your application. Then there's output impedance, where the resistance gets added to your leakage inductance, which also depends on your applciation.
At 4mS, you're probably talking about ferrite, even if the frequency of the pulse train looks to be within the realms of iron. It's more the risetime of the pulse (which you haven't specified yet) that will explore the differences between steel and ferrite.
The pulse length requires a certain area of core, you can't exceed its volt.seconds product, if you do it saturates.
Note that a uni-directional pulse has a DC component. A train of those pulses will saturate a transformer, unless you do something to reset the flux between pulses. AC coupling the pulses into it with a capacitor works, but you may find that distorts the pulses more than you want. If it does, then you may have to do something more complicated, or rethink entirely.
Registered Member #61406
Joined: Thu Jan 05 2017, 11:31PM
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Posts: 268
It's not a transformer persay, but it can isolated two networks, if I have two of the circuit charging the battery, the capacitor discharge at the same time. I'm not sure how to do it, except with a circuit control the discharge of the two circuit at different times.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
If it's *not* a transformer, per se or not, then a different design process might apply. What is it? Add a schematic, or a photograph, or a link. Your OP seemed to suggest it was a transformer, in the physical sense.
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Selection of a transformer
