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Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
I'd go for the UC384x family as more than half of the embedded smps that I encounter use one there is a wealth of info. on the net, easy to get help.
Use good quality capacitors for your smps circuitry as the most common smps failure that I come across is high esr or leaked electrolytics ... designers frequently underestimate the stresses on and lifetime of electrolytic capacitors. In order; ceramic, os-con then low-impedance high-temperature (105C or more) electrolytics.
P.S. volume efficiency (watts per cubic meter) is probably one of the least important aspects normally it's - watts per dollar, which includes watts per pcb area (profitability) - efficiency (marketing) - watts per kilogram (airborne etc.) - second-sourcing (to ensure production) - reliability (reputation) - emc (statutory) - safety (liabilities) then maybe volume efficiency. Maybe our resident smps designers could re-prioritize/add to the list.
Registered Member #1064
Joined: Tue Oct 16 2007, 05:04PM
Location:
Posts: 42
So you're going for EE Ph.D. Good Luck
Just out of curiosity, what voltage and current would you like your 10 Megawatt transformer to input and output?
What are you going to do with a monster transformer like this?
Have you considered how you are going to test this transformer?
JPL used to use some transformers at about this KVA. They operated the transformers at 400 hertz and used a 60 hertz to 400 hertz motor generator to power the transformers. They varied the voltage to the generator field to vary the output voltage.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Carl Pugh wrote ...
So you're going for EE Ph.D. Good Luck
Just out of curiosity, what voltage and current would you like your 10 Megawatt transformer to input and output?
What are you going to do with a monster transformer like this?
Have you considered how you are going to test this transformer?
JPL used to use some transformers at about this KVA. They operated the transformers at 400 hertz and used a 60 hertz to 400 hertz motor generator to power the transformers. They varied the voltage to the generator field to vary the output voltage.
I havent fully figured this out yet, but i plan to use 1000 modules per Megawatt. And i would build and test in stages, not all at once, it should be 800Kg, and cube 1.1 meters on each side.(i could be wrong about the math as thats an approximation.)
so once its made out of all its modules, then they can be tested individually, and then together. so that is how i would test it. CMC, paralellable, if one fails then the load shed upto 1.25kW continous for each module is meant to be survivable.
As for the voltage, that depends, the SOFC puts out 0.95-1.7 volts out of a maximum half reaction of 2.2V, so the number of plates matters. it may be several hundred volts input, several thousand out. obviously matching impedance from the battery/fuel cell, and the impedance to the motor is what the transformer is for.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
This is beginning to sound feasible. according to my rough calculations, each module would be ~11 cm cubed, so, with liguid cooling, it seems quite plausible.
What kind of efficiency are you expecting? ie how much heating?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Look at the last few pages here: (pg 18 if your in a hurry)
]parallel_smps.pdf[/file]
You should read the whole thing, but i have always wondered about some of the points i see here in this article, well others had these problems too and found solutions! The diode and resistor master-slave concept in particular for aircraft redundancy, if a few modules fail the others reorganize and continue.
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