DC transformer, x-Chapters 9x.16

x-Chapters 9x.16, about DC transformers, AKA bus converters. It's a synchronous dc-dc converter, with in/out voltage ratio set by a fixed switching duty cycle. Like ac transformers, they transfer power in either direction, as a function of who's above the ratio. The current-ratio also obeys the voltage-ratio rule, like an ac transformer. As bus-converters, they're used to convert a 48V distributed bus, to lower voltages for local use.

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Winfield Hill
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Winfield Hill wrote in news:qohu9001kk1 @drn.newsguy.com:

Anything in your book on how a big 10kVA line conditioning transformer works?

You know, the ones with cap banks in them that put out at 60Hz even when the line or freq sags.

We had a back up generator that caused our UPS systems to fail to notice the power being back up, and it was due to the generator somehow making not quite sinosidal waveform or maybe it was full of spikes... not sure, but these transformers in line with the generator output fixed the issue.

"Sola" is the most common brand I see, and is what we installed in the house in Virginia. It was 750 Lbs overall for the 20kVA capacity we needed.

Reply to
DecadentLinuxUserNumeroUno

Nice chapter!

Fig 9.2.73, upper right terminals should be Vout(HV) not Vout(LV).

Arie

Reply to
Arie de Muynck

The circuit schematic and PCB board in the photo is PWR-671, in my RIS-671 project file. It uses an IR2085 for PWM and MOSFET driving, and has a zener+7812, so Vmax could be up to 450V, if R13, D3, elec caps, and MOSFETs are chosen properly.

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I first created it for a magnet-control project. Three different voltages were needed, with 150W capability, this way we needed only one module. As the field coils were switched on and off, the energy went back into the big source-supply cap.

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Reply to
Winfield Hill

Thanks, Arie, I've made a note for our next printing.

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Winfield Hill

Correction: Although most of IR's HV MOSFET driver ICs work to 600V, the IR2085 is only good to 130V. But it's faster, with deadtimes as low as 50ns.

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Reply to
Winfield Hill

what on earth was that schematic drawn in?

Reply to
Lasse Langwadt Christensen

Win, you really need to cover Royer and Royer Jensen converters. That was the original DC Transformers

Williams paper on optimising Roger efficiency is excellent

Cheers

Klaus

Reply to
klaus.kragelund

Thanks, Klaus, I'm sure you're right. But I have very little experience with them at this point. Maybe you'd like to conribute a guest section?

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Reply to
Winfield Hill

Certainly, all though I am no expert, still more to learn

I will send you a message on LinkedIn

Cheers

Klaus

Reply to
klaus.kragelund

Sorry, I'm not linked in. :-) Just use my yahoo email, which is up-to-date.

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Reply to
Winfield Hill

Yes, it doesn't look as good as most of my schematics. But it was drawn 10 years ago in PCAD, and then imported into Altium. More relevant, it was done quickly, using the standard schematic component images, which are big and clunky. With those images, one needs to allow more space between things or it looks a mess. With a little extra care, PCAD can make very nice schematics. So can Protel and Altium, although not quite as nice as PCAD. None of them are decent drawing programs, they don't let you decently control line widths, angles, curves, etc. Altium does let us pick font types, fine-tune sizes, and set snap grids.

We use Illustrator for our book's figures, but that's a lot more time consuming. We make a careful hand drawing that's as close as possible to our final expected figure. Our publisher, C.U.P., hires our drawings out to a firm in India, where a few of their staff have become quite proficient, after doing many hundreds of our schematics.

Paul has become a true Illustrator expert, and fixes and cleans up their work, then we sit together and hand edit each one for a final pass. But even with this high level of scrutiny, it's amazing what stupid careless mistakes leak through. When you're adjusting line spacing, etc., it's easy to overlook that the wire is going to the wrong place, etc. I try to examine the drawing in stages, first scanning for one type of issue, like part values, then for another, wiring connections, then the component shape, etc. But in the process we have still ended up with some silly errors, like +,- symbols backwards on op-amps, etc.

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Reply to
Winfield Hill

Our once chronic bug was flipping an opamp symbol to make the + and - inputs fit the circuit nicely, which also flipped the power pins, which we then connected V+ on top, V- on bottom, which was wrong. That is now on our PCB checklist, and we assign someone to check it yet again just for luck.

I think PADS makes nice looking schematics, but it's inclined towards jaggies.

How many copies of AoE have been sold?

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John Larkin         Highland Technology, Inc 

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jlarkin

I've made that mistake, but some time ago created a second op-amp symbol to use to solve that issue.

I dunno. In its 15th printing now, but that doesn't mean 150k copies. Probably between 75k and 125k.

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Reply to
Winfield Hill

You can still pull up the wrong symbol!

I've bought a dozen or two. I give them to new hires if they don't have one already. Plus my copies at work, at home, and in the cabin.

Thanks!

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John Larkin         Highland Technology, Inc 
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Reply to
John Larkin

You've bought about 0.02% of all the copies!

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Reply to
Winfield Hill

And enough of Phil's books to put his kids through college for about nine minutes.

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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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John Larkin

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