Electronics > Projects, Designs, and Technical Stuff
Help with Pulse Transformer Design
Berni:
--- Quote from: KurtK on August 23, 2019, 03:18:08 pm ---So you are spooked by the mentioning of 50KW, and for that I deserve a personal attack, thank you very much. Well I guess I had it coming and can only thank myself, I must have exceed some maximum allowed avereage power for posting on this forum that I wasn't aware of.
To the rest of the contributes in this post, I tank you for your input.
Cheers!
--- End quote ---
I'm pretty sure there is no such power limit on this forum.
Just that saying its a pulse transformer generally means its a transformer designed for wide bandwidth and typically high speed operation. These are typically small low power transformers such as used for signal isolation (Ethernet, SPDIF), driving floating transistors, baluns etc... These transformers are typically the size of a sugar cube and don't handle any sort of high power levels. I know its a bit odd to call these pulse transformers but i suppose pulses are wide bandwidth when you look at there frequency content.
So describing it as that gave a large majority of users trying to help the completely wrong idea of what you want, hence leading to all round confusion at conflicting specifications.
This is the sort of specialized transformer you would find in some sort of physics experiment rig to produce some weird high energy effect or driving some ridiculously high pulse power radar equipment or something along those lines. Stuff that you really want someone on your team that knows what they are doing. Especially since the construction of such a transformer that performs at its best can also be quite tricky and costly.
The number one thing for efficient transformers at these powers is to keep leakage inductance as low as possible and have hugely thick wingdings to provide the low resistance required to keep the pesky P=I^2*R at bay despite the huge currents. The core material is not that hugely important since you can simply use enough turns to keep the BH curve where it is happy. Even laminated steel can operate operate into the KHz range with some careful design. Ferromagnetic cores mainly give you benefit by reducing the number of required turns and thus those resistive losses that are your biggest enemy, core loss should be tiny compared to them.
--- Quote from: patrick1 on August 23, 2019, 03:35:28 pm ---Funny i just fixed a bunch of analog panel meters. - this would likley be your best way too measure efficiency in my pamphlet
get yourself a sweep signal generator... and let it run one, till you find your best numbers... even if you decide too take another route, - my thinking is, you can never have too many spare panel meters... and @ $3~ each... dosnt hurt too bad.
YOUTUBE LINK - this is a video i made yesterday about efficiency in transformers. you may fund it interesting ;=D
--- End quote ---
What you describe in the video is one of the big reasons why pretty much all large switch mode power supplies are using topologies that drive current in both directions trough the transformer such as the PushPull or Full Bridge designs (And additional tricks are used to make these even more efficient). Driving the transformer both positive and negative makes for more efficient use of the core because its traversing across all of its available BH curve rather than just the top half of it. The 50/60Hz mains transformers operate in this way. But the reason that small power switching supplies don't use this superior way of driving a transformer is that the electronics are more complex for it, so it becomes more cost effective to reduce component count with the Flyback topology and simply make the transformer a bit larger (But since its a tiny transformer to begin with that's not much of a cost penatly)
Oh and as for the solar power thing. The fact that the voltage is rising too high is the fault of an overloaded power distribution network. The voltage drop on the wires to the transformer and perhaps the transformer itself are under rated so they are not transferring the power back into the grid. Because the current is flowing the other way means any voltage drops are actually added on top of the voltage. But typically grid tied solar inverters don't tend scale back production according to voltage, they will output as much power as they can suck from the panels. Its only once the voltage gets too high a safety cutoff will kick in and shut it down to prevent damage. Voltage regulation is the job of the grid, not the inverter. Due to the way AC power grids work if there is more power being generated than is being consumed what will actually go up is the frequency, not the voltage.
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