Need to get constant 15v DC from a variable buss
Need to get constant 15v DC from a variable buss
(OP)
I need to pull approx 15V DC at up to 10 amps from a constantly varying DC buss that ranges from 0 to up to 200V DC at up to 150 amps. I'm not too familiar with electronics but I do have an electrical background. Thanks for any help!
James
James





RE: Need to get constant 15v DC from a variable buss
RE: Need to get constant 15v DC from a variable buss
If your supply was always greater than 15 volts, the supply is a snap. If it drops below 15 volts once in a while, it's a little trickier, you're forced into a switchmode supply that essentialy converts DC to AC so that it can be "transformed" up to a higher voltage, and then back to regulated DC.
If your supply spends a lot of time around 0 volts, then you'd need capacitors or something to maintain the voltage during the sags. If your supply spends a significant amount of time at 0 volts, you're screwed.
Can you provide some more specifics about the supply bus?
RE: Need to get constant 15v DC from a variable buss
RE: Need to get constant 15v DC from a variable buss
RE: Need to get constant 15v DC from a variable buss
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RE: Need to get constant 15v DC from a variable buss
-----------------------------------
Start each new day with a smile.
Get it over with.
RE: Need to get constant 15v DC from a variable buss
Let me give you more information about what I'm trying to do.
The DC is generated by a gas motor driven three phase AC generator, which in turn goes through a 3 phase rectifier. The rotor for this AC generator is currently powered by a DC battery. (DC rotor spinning in the three phase AC stator)
I'm trying to tap off of the unregulated main DC buss to provide ~+15Vdc to recharge the battery and power the rotor during operation. This would allow a much smaller battery to be used and eliminate the need to change them often.
RE: Need to get constant 15v DC from a variable buss
Why not use a battery charger fed directly from the AC generator output across two phases, and avoid DC/DC conversion completely? DC/DC converters are expensive; battery chargers are relatively cheap becase they are a mass-market item.
Your small battery provides what we would call 'field flashing' on a large utility generating set to initially establish the output voltage, and then the set is self-sustaining by feeding a small proportion of its output back in to the field via the battery charger.
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Start each new day with a smile.
Get it over with.
RE: Need to get constant 15v DC from a variable buss
Yes, the battery would flash the rotor to get the generator going. Currently however, the battery powers the rotor exclusively thus my desire to tap off the DC buss for power.
There will be a variable resistor in series with the supply so the output current can be regulated.
RE: Need to get constant 15v DC from a variable buss
RE: Need to get constant 15v DC from a variable buss
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